Thread: network programming

i have 2 questions that i'm sure are easy to answer but i can't find the answer anywhere. I'm trying to write a program that will sent information though a UDP datagram from port 2006 on the source computer to port 2007 on the destination computer. i cannot figure out how to set the source port to 2006. i got the destination port to work.

second in the data part of the datagram i need it to be padded in front and in back with hex '00'.

here is my code

Code:

#include <ws2tcpip.h>
#include <iostream>
#include <stdio.h>
#include <string.h>
#include <winsock.h>
#include <sys\types.h>

using namespace std;

#define MDYN2 "10.0.1.20"	//IP address for MDYN2 computer
#define OPCON "10.0.1.99"	//IP address for OPCON computer


/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
//main program:	this program creates a connection between this computer (should be OPCON) and MDYN2 (10.0.1.20). it then
//				sends a datagram to MDYN2 containg the ":cabsave" command to try and get MDYN2 to save information as if it
//				was comming form the OpCon program on OPCON computer.
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

int main(void)
{
	WSADATA wsaData;

	if (WSAStartup(MAKEWORD(2, 0),&wsaData) != 0)
	{
	fprintf(stderr,"WSAStartup()failed");
	exit(1);
	}

    struct addrinfo hints;			//used to help fill in results
	struct addrinfo* results;		//where the adder info goes (linked list)
//	struct addrinfo* pointer;		//points to current result in linked list. might need this...
    int status;						//status of all the functions that return a status (reused multiple times)
	int sock;						//socket
	char* message;					//the message that will be sent
	
	message = ":cabsave saveFromProgram";

	//intilize hints first set to 0 then fill
	memset(&hints, 0, sizeof hints);
    hints.ai_family = AF_INET;			//IPv4 only (computer is too old for IPv6)
    hints.ai_socktype = SOCK_DGRAM;		//UDP connection (or lack there of)
	hints.ai_flags = AI_PASSIVE;		//sets ip to this computer (should be on Opcon: 10.0.1.99 (94?))

	//sets results, checkes status, and tell you if it doesn't work all on one line.
	if((status = getaddrinfo(MDYN2, "2007", &hints, &results)) != 0) 
	{
        printf("getaddrinfo: %s\n", gai_strerror(status));
		system("pause");
		return 0;
    }

	//
	//might need to shearch thought the linked list; though, i dout it.
	//

	//set socket and connect
	sock = socket(results->ai_family, results->ai_socktype, results->ai_protocol);

	//bind(sock, results->ai_addr, results->ai_addrlen);
	
	status = sendto(sock, message, strlen(message), 0, results->ai_addr, sizeof(*results->ai_addr)); 

	//connect is recived at a spcific socket. (mightnot need this eather...
	//connect(sock, results->ai_addr, results->ai_addrlen);

	//bind (might not have to to this) sends though a spcific socket
	

	status = shutdown(sock, 2);
	printf("program completed\n");
	system("pause");
	return 0;
}