testProgs/sapWatch.cpp

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// Copyright (c) 1996-2012, Live Networks, Inc.  All rights reserved
// A program that receives and prints SDP/SAP announcements
// (on the default SDP/SAP directory: 224.2.127.254/9875)

#include "Groupsock.hh"
#include "GroupsockHelper.hh"
#include "BasicUsageEnvironment.hh"
#include <stdio.h>

static unsigned const maxPacketSize = 65536;
static unsigned char packet[maxPacketSize+1];

int main(int argc, char** argv) {
  // Begin by setting up our usage environment:
  TaskScheduler* scheduler = BasicTaskScheduler::createNew();
  UsageEnvironment* env = BasicUsageEnvironment::createNew(*scheduler);


  // Create a 'groupsock' for the input multicast group,port:
  char const* sessionAddressStr = "224.2.127.254";
  struct in_addr sessionAddress;
  sessionAddress.s_addr = our_inet_addr(sessionAddressStr);

  const Port port(9875);
  const unsigned char ttl = 0; // we're only reading from this mcast group

  Groupsock inputGroupsock(*env, sessionAddress, port, ttl);

  // Start reading and printing incoming packets
  // (Because this is the only thing we do, we can just do this
  // synchronously, in a loop, so we don't need to set up an asynchronous
  // event handler like we do in most of the other test programs.)
  unsigned packetSize;
  struct sockaddr_in fromAddress;
  while (inputGroupsock.handleRead(packet, maxPacketSize,
                                   packetSize, fromAddress)) {
    printf("\n[packet from %s (%d bytes)]\n", AddressString(fromAddress).val(), packetSize);

    // Ignore the first 8 bytes (SAP header).
    if (packetSize < 8) {
      *env << "Ignoring short packet from " << AddressString(fromAddress).val() << "%s!\n";
      continue;
    }

    // convert "application/sdp\0" -> "application/sdp\0x20"
    // or all other nonprintable characters to blank, except new line
    unsigned idx = 8;
    while (idx < packetSize) {
      if (packet[idx] < 0x20 && packet[idx] != '\n') packet[idx] = 0x20;
      idx++;
    }

    packet[packetSize] = '\0'; // just in case
    printf((char*)(packet+8));
  }

  return 0; // only to prevent compiler warning
}

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