How to listen continuosly SSDP response after sending M-SEARCH - upnp

Question

I would like to search Sat>IP servers on the network. Sat>IP servers advertise their presence to other Sat>IP servers and clients.
I must not continuosly send M-SEARCH messages but that instead it listens to server NOTIFY messages.
After initalizing network settings of my device, I'm sending M-SEARCH message and getting response if there is already any active Sat>IP server.
However, I couldn't get any response, If I opens Sat>IP server after sending M-SEARCH message.
Here's my code.
void SatIP::InitDiscoverThread()
{
if(INVALID_THREAD_CHK == DiscoverThreadChk)
{
pthread_attr_t attr;
pthread_attr_init(&attr);
pthread_attr_setstacksize(&attr, PTHREAD_STACK_SIZE);
printf("InitDiscoverThread pthread_create\n");
DiscoverThreadChk = PTH_RET_CHK(pthread_create(&DiscoverThreadID, &attr, DiscoverThreadFunc, this));
if(DiscoverThreadChk != 0)
{
ASSERT(0);
}
}
}
void SatIP::FinalizeDiscoverThread()
{
if(INVALID_THREAD_CHK != DiscoverThreadChk)
{
printf("FinalizeDiscoverThread pthread_cancel\n");
pthread_cancel(DiscoverThreadID);
DiscoverThreadChk = INVALID_THREAD_CHK;
close(discoverSocket);
}
}
void *SatIP::DiscoverThreadFunc(void* arg)
{
SatIP* satip = (SatIP *)arg;
satip->ListenSSDPResponse();
pthread_exit(NULL);
}
bool SatIP::SendMSearchMessage()
{
vSatIPServers.clear();
FinalizeDiscoverThread();
const char *searchSatIPDevice = "M-SEARCH * HTTP/1.1\r\n" \
"HOST: 239.255.255.250:1900\r\n" \
"MAN: \"ssdp:discover\"\r\n" \
"MX: 2\r\n" \
"ST: urn:ses-com:device:SatIPServer:1\r\n\r\n";
struct sockaddr_in upnpControl, broadcast_addr;
discoverSocket = socket(AF_INET, SOCK_DGRAM, 0);
if (discoverSocket == INVALID_SOCKET)
{
printf("socked failed INVALID_SOCKET\n");
return false;
}
struct timeval tv;
tv.tv_sec = 1;
tv.tv_usec = 0;
if(setsockopt(discoverSocket, SOL_SOCKET, SO_RCVTIMEO, (char*)&tv, sizeof(tv)) == SOCKET_ERROR)
{
printf("setsockopt timeout failed\n");
close(discoverSocket);
return false;
}
socklen_t ttl = 2;
if(setsockopt(discoverSocket, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)) == SOCKET_ERROR)
{
printf("setsockopt TTL failed\n");
close(discoverSocket);
return false;
}
if(setsockopt(discoverSocket, SOL_SOCKET, SO_BROADCAST, searchSatIPDevice, sizeof(searchSatIPDevice)) == SOCKET_ERROR)
{
printf("setsockopt broadcast failed\n");
close(discoverSocket);
return false;
}
upnpControl.sin_family = AF_INET;
upnpControl.sin_port = htons(0);
upnpControl.sin_addr.s_addr = INADDR_ANY;
if (bind(discoverSocket, (sockaddr*)&upnpControl, sizeof(upnpControl)) == SOCKET_ERROR)
{
printf("bind failed\n");
close(discoverSocket);
return false;
}
broadcast_addr.sin_family = AF_INET;
broadcast_addr.sin_port = htons(1900);
broadcast_addr.sin_addr.s_addr = inet_addr("239.255.255.250");
for(int i = 0; i < 3; i++)
{
if(sendto(discoverSocket, searchSatIPDevice, strlen(searchSatIPDevice), 0, (sockaddr *)&broadcast_addr, sizeof(broadcast_addr)) == SOCKET_ERROR)
{
//printf("sendto failed\n");
close(discoverSocket);
return false;
}
else
{
usleep(10*100);
}
}
InitDiscoverThread();
return true;
}
void SatIP::ListenSSDPResponse()
{
while(1)
{
char buf[512];
memset(buf, 0, 512);
struct sockaddr_in broadcast_addr;
broadcast_addr.sin_family = AF_INET;
broadcast_addr.sin_port = htons(1900);
broadcast_addr.sin_addr.s_addr = inet_addr("239.255.255.250");
int bcLen = sizeof(broadcast_addr);
//bool bRet = false;
while (recvfrom(discoverSocket, buf, 512, 0, (struct sockaddr*)&broadcast_addr, (socklen_t*)&bcLen) > 0)
{
printf("buf:%s\n",buf);
SATIP_SERVER_DESCRIPTION stServerDesc;
ostringstream ss;
if(strstr(buf, "device:SatIPServer"))
{
int i = 0;
char *deviceIp = strstr(buf, "LOCATION:") + 9; // get xml location including server description
while(deviceIp[i] == ' ') i++; // remove spaces from string
while(!isspace(deviceIp[i]))
{
ss << deviceIp[i];
++i;
}
stServerDesc.location = ss.str().c_str();
printf("location:%s\n",stServerDesc.location.c_str());
ss.str(""); // clear ss
i=0; // clear counter
deviceIp = strstr(buf, "http://") + 7; // get ip address
while(deviceIp[i] != ':')
{
ss << deviceIp[i];
++i;
}
stServerDesc.ipAddr = ss.str().c_str();
printf("ipAddr:%s\n", stServerDesc.ipAddr.c_str());
DownloadDeviceDescription(&stServerDesc);
stServerDesc.macAddr = GetMACAddressviaIP(stServerDesc.ipAddr);
printf("macAddr:%s\n", stServerDesc.macAddr.c_str());
if(IsServerProperToAdd(&stServerDesc))
vSatIPServers.push_back(stServerDesc);
printf("\n");
//bRet = true;
}
memset(buf, 0, 512);
}
}
}
How can I fix this issue? Any help would be appreciated.

Answer 1

Listening SSDP notify message is not related to sending M-SEARCH message. Devices like Sat>IP send NOTIFY message to 239.255.255.250 periodically even if you don't send M-SEARCH message. So, you should join a multicast group and receives from the group.
You can use the listener program in the following link by changing HELLO_PORT as 1900 and HELLO_GROUP as "239.255.255.250".
http://ntrg.cs.tcd.ie/undergrad/4ba2/multicast/antony/example.html
/*
* listener.c -- joins a multicast group and echoes all data it receives from
* the group to its stdout...
*
* Antony Courtney, 25/11/94
* Modified by: Frédéric Bastien (25/03/04)
* to compile without warning and work correctly
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <time.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#define HELLO_PORT 1900
#define HELLO_GROUP "239.255.255.250"
#define MSGBUFSIZE 256
main(int argc, char *argv[])
{
struct sockaddr_in addr;
int fd, nbytes,addrlen;
struct ip_mreq mreq;
char msgbuf[MSGBUFSIZE];
u_int yes=1; /*** MODIFICATION TO ORIGINAL */
/* create what looks like an ordinary UDP socket */
if ((fd=socket(AF_INET,SOCK_DGRAM,0)) < 0) {
perror("socket");
exit(1);
}
/**** MODIFICATION TO ORIGINAL */
/* allow multiple sockets to use the same PORT number */
if (setsockopt(fd,SOL_SOCKET,SO_REUSEADDR,&yes,sizeof(yes)) < 0) {
perror("Reusing ADDR failed");
exit(1);
}
/*** END OF MODIFICATION TO ORIGINAL */
/* set up destination address */
memset(&addr,0,sizeof(addr));
addr.sin_family=AF_INET;
addr.sin_addr.s_addr=htonl(INADDR_ANY); /* N.B.: differs from sender */
addr.sin_port=htons(HELLO_PORT);
/* bind to receive address */
if (bind(fd,(struct sockaddr *) &addr,sizeof(addr)) < 0) {
perror("bind");
exit(1);
}
/* use setsockopt() to request that the kernel join a multicast group */
mreq.imr_multiaddr.s_addr=inet_addr(HELLO_GROUP);
mreq.imr_interface.s_addr=htonl(INADDR_ANY);
if (setsockopt(fd,IPPROTO_IP,IP_ADD_MEMBERSHIP,&mreq,sizeof(mreq)) < 0) {
perror("setsockopt");
exit(1);
}
/* now just enter a read-print loop */
while (1) {
addrlen=sizeof(addr);
if ((nbytes=recvfrom(fd,msgbuf,MSGBUFSIZE,0,
(struct sockaddr *) &addr,&addrlen)) < 0) {
perror("recvfrom");
exit(1);
}
puts(msgbuf);
}
}