c-stun-client-demo.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>

#define MAXLINE 200

/*
*
* STUN(RFC5389) client demo by Chris <nodexy@gmail>
*
* Test by turnserver-0.6 from http://turnserver.sourceforge.net
*
* @ 2012-2-27 AT Shenzhen, China
* @ 2012-2-29 version 0.1
*/

int stun_xor_addr(char * stun_server_ip,short stun_server_port,short local_port,char * return_ip_port);


int main(int argc, char *argv[])
{
        if (argc != 4) {
		printf("STUN(RFC5389) client demo by Chris <nodexy@gmail>\n");
                printf("usage: %s <server_ip> <server_port> <local_port>\n\n", argv[0]);
                exit(1);
        }


        printf("Main start ... \n");

	int n = 0;
	char return_ip_port[50]; 
	n = stun_xor_addr(argv[1],atoi(argv[2]),atoi(argv[3]),return_ip_port);
	if (n!=0)
                printf("STUN req error : %d\n",n);
        else
                printf("ip:port = %s\n",return_ip_port);

	printf("Main over.\n");

}

int stun_xor_addr(char * stun_server_ip,short stun_server_port,short local_port,char * return_ip_port)
{
	struct sockaddr_in servaddr;
	struct sockaddr_in localaddr;
	unsigned char buf[MAXLINE];
	int sockfd, i;
        unsigned char bindingReq[20];    

	int stun_method,msg_length;
	short attr_type;
	short attr_length;
	short port;
	short n;


        //# create socket 
	sockfd = socket(AF_INET, SOCK_DGRAM, 0); // UDP

	// server 
	bzero(&servaddr, sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	inet_pton(AF_INET, stun_server_ip, &servaddr.sin_addr);
	servaddr.sin_port = htons(stun_server_port);
    
	// local
	bzero(&localaddr, sizeof(localaddr));
        localaddr.sin_family = AF_INET;
        //inet_pton(AF_INET, "192.168.0.181", &localaddr.sin_addr);
        localaddr.sin_port = htons(local_port);

	n = bind(sockfd,(struct sockaddr *)&localaddr,sizeof(localaddr));
	//printf("bind result=%d\n",n);

        printf("socket opened to  %s:%d  at local port %d\n",stun_server_ip,stun_server_port,local_port);

        //## first bind 
	* (short *)(&bindingReq[0]) = htons(0x0001);    // stun_method
	* (short *)(&bindingReq[2]) = htons(0x0000);    // msg_length
	* (int *)(&bindingReq[4])   = htonl(0x2112A442);// magic cookie

	*(int *)(&bindingReq[8]) = htonl(0x63c7117e);   // transacation ID 
	*(int *)(&bindingReq[12])= htonl(0x0714278f);
	*(int *)(&bindingReq[16])= htonl(0x5ded3221);



        printf("Send data ...\n");
        n = sendto(sockfd, bindingReq, sizeof(bindingReq),0,(struct sockaddr *)&servaddr, sizeof(servaddr)); // send UDP
	if (n == -1)
        {
            printf("sendto error\n");
            return -1;
        }

	// time wait 
	sleep(1);

        printf("Read recv ...\n");
        n = recvfrom(sockfd, buf, MAXLINE, 0, NULL,0); // recv UDP
        if (n == -1)
	{
	    printf("recvfrom error\n");
	    return -2;
	}
	//printf("Response from server:\n");
	//write(STDOUT_FILENO, buf, n);

	if (*(short *)(&buf[0]) == htons(0x0101))
	{
		printf("STUN binding resp: success !\n");

		// parse XOR
		n = htons(*(short *)(&buf[2]));
		i = 20;
        	while(i<sizeof(buf))
       	 	{
                	attr_type = htons(*(short *)(&buf[i]));
			attr_length = htons(*(short *)(&buf[i+2]));
			if (attr_type == 0x0020)
			{
				// parse : port, IP 

				port = ntohs(*(short *)(&buf[i+6]));
				port ^= 0x2112;
				/*printf("@port = %d\n",(unsigned short)port);

				printf("@ip   = %d.",buf[i+8] ^ 0x21);
				printf("%d.",buf[i+9] ^ 0x12);
				printf("%d.",buf[i+10] ^ 0xA4);
				printf("%d\n",buf[i+11] ^ 0x42);
				*/

				sprintf(return_ip_port,"%d.%d.%d.%d:%d",buf[i+8]^0x21,buf[i+9]^0x12,buf[i+10]^0xA4,buf[i+11]^0x42,port);
	
				break;
			}
			i += (4  + attr_length);
        	}
	}


        // TODO: bind again 

	close(sockfd);
        printf("socket closed !\n");


	return 0;
}