Single-thread port scanner written in C

# Include <stdio. h>
# Include <string. h>
# Include <winsock2.h>

# Pragma comment (Lib, "ws2_32 ")

Void scan1 (char *);
Void scan2 (char *, char *, char *);
Void usage (char *);

Int main (INT argc, char * argv [])
{
If (argc! = 2 & argc! = 4) usage (argv [0]);
Else
{
If (argc = 2) scan1 (argv [1]);
Else
{
If (argc = 4) scan2 (argv [1], argv [2], argv [3]);
}
}
}

Void usage (char * Help)
{
Printf ("========================================== =====/N ");
Printf ("netxscan_port ver0.1 by netxfly@21cn.com/N ");
Printf ("% S <targetip> [Options]/n", help );
Printf ("[Option]/n ");
Printf ("<startport> <endport>/N ");
Printf ("Usage:/n ");
Printf ("% s 192.168.1.1/N", help );
Printf ("% s 192.168.1.1 21 5000/N", help );
Printf ("========================================== =====/N ");

Exit (-1 );
}

Void scan1 (char * target)
{

Int I;
Wsadata;
Socket netxfly;
Struct sockaddr_in sin;

Int ports [18] = {80,110,111,135,139,443,445,554,143 };

If (wsastartup (makeword (2, 2), & wsadata )! = 0)
{
Printf ("Startup Winsock failed.../N ");
Exit (-1 );
}

Memset (& sin, 0, sizeof (SIN ));

For (I = 0; I <18; I ++)
{
If (netxfly = socket (af_inet, sock_stream, 0) = invalid_socket)
{
Printf ("create socket err.../R/N ");
Exit (-1 );
}

Sin. sin_family = af_inet;
Sin. sin_addr.s_addr = inet_addr (target );
Sin. sin_port = htons (ports [I]);

If (connect (netxfly, (struct sockaddr *) & sin, sizeof (SIN ))! = Socket_error)
{
Printf ("port % d is open/R/N", ports [I]);
Closesocket (netxfly );
}
Closesocket (netxfly );
}

Wsacleanup ();
}

Void scan2 (char * target, char * Start, char * end)
{

Int I;
Wsadata;
Socket netxfly;
Struct sockaddr_in sin;

Int startport = atoi (start );
Int endport = atoi (end );

If (wsastartup (makeword (2, 2), & wsadata )! = 0)
{
Printf ("Startup Winsock failed.../N ");
Exit (-1 );
}

If (netxfly = socket (af_inet, sock_stream, 0) = invalid_socket)
{
Printf ("create socket err.../R/N ");
Exit (-1 );
}

Memset (& sin, 0, sizeof (SIN ));

For (I = startport; I <= endport; I ++)
{
If (netxfly = socket (af_inet, sock_stream, 0) = invalid_socket)
{
Printf ("create socket err.../R/N ");
Exit (-1 );
}

Sin. sin_family = af_inet;
Sin. sin_addr.s_addr = inet_addr (target );
Sin. sin_port = htons (I );

If (connect (netxfly, (struct sockaddr *) & sin, sizeof (SIN ))! = Socket_error)
{
Printf ("port % d Open/R/N", I );
Closesocket (netxfly );
}
Closesocket (netxfly );
}

Wsacleanup ();
}