SSDP UDP broadcast ...

#include ＜stdlib.h＞
#include ＜unistd.h＞
#include ＜string.h＞
#include ＜sys/select.h＞
#include ＜sys/time.h＞
#include ＜sys/socket.h＞
#include ＜netdb.h＞
#include ＜stdio.h＞


#define RESPONSE_BUFFER_LEN 1024
#define SSDP_MULTICAST      "239.255.255.250"
#define SSDP_PORT           1900

int main (int argc, const char * argv[])
{
int sock;
size_t ret;
unsigned int socklen;
struct sockaddr_in sockname;
struct sockaddr clientsock;
struct hostent *hostname;
char data[] = 
"M-SEARCH * HTTP/1.1\r\n"
"Host: 239.255.255.250:1900\r\n"
"Man: \"ssdp:discover\"\r\n"
"ST:upnp:rootdevice\r\n"
"MX:3\r\n"
"\r\n";
char buffer[RESPONSE_BUFFER_LEN];
unsigned int len = RESPONSE_BUFFER_LEN;
fd_set fds;
struct timeval timeout;


hostname = gethostbyname(SSDP_MULTICAST);
hostname->h_addrtype = AF_INET;


if((sock = socket(PF_INET, SOCK_DGRAM, 0)) == -1)
{
printf("err: socket() failed");
return -1;
}


memset((char*)&sockname, 0, sizeof(struct sockaddr_in));
sockname.sin_family=AF_INET;
sockname.sin_port=htons(SSDP_PORT);
sockname.sin_addr.s_addr=*((unsigned long*)(hostname->h_addr_list[0]));


ret=sendto(sock, data, strlen(data), 0, (struct sockaddr*) &sockname, 
sizeof(struct sockaddr_in));
if(ret != strlen(data))
{
printf("err:sendto");
return -1;
}


/* Get response */
FD_ZERO(&fds);
FD_SET(sock, &fds);
timeout.tv_sec=10;
timeout.tv_usec=10;


if(select(sock+1, &fds, NULL, NULL, &timeout) < 0)
{
printf("eer:select");
return -1;
}
if(FD_ISSET(sock, &fds))
{
socklen=sizeof(clientsock);
if((len = recvfrom(sock, buffer, len, MSG_PEEK, &clientsock, &socklen)) == (size_t)-1)
{
printf("err: recvfrom");
return -1;
}


buffer[len]='\0';
close(sock);


/* Check the HTTP response code */
if(strncmp(buffer, "HTTP/1.1 200 OK", 12) != 0)
{
printf("err: ssdp parsing ");
return -1;
}


printf(buffer);
return 0;


}
else
{
printf("err: no ssdp answer");
return -1;
}
}




Refernece: http://www.experts-exchange.com/Networking/Protocols/Transport/UDP/Q_23896333.html