shithub: opus-tools

Info  •  Files  •  Log  •  Branches

Get the link-layer header type from pcap_datalink.

Instead of using compile-time switches to choose loopback
or eth header parsing in sniff mode, ask libpcap what it
will be supplying and parse based on that.

Also abort if the link layer type isn't ethernet or loopback,
or if the header doesn't indicate IP/UDP.

--- a/src/opusrtp.c

+++ b/src/opusrtp.c

@@ -67,6 +67,7 @@

   ogg_stream_state *stream;

   FILE *out;

   int seq;

+  int linktype;

 } state;

 /* helper, write a little-endian 32 bit int to memory */

@@ -633,29 +634,45 @@

   packet = data;

   size = header->caplen;

-#if ETH

-  if (parse_eth_header(packet, size, &eth)) {

-    fprintf(stderr, "error parsing eth header\n");

-    return;

+  /* parse the link-layer header */

+  switch (params->linktype) {

+    case DLT_EN10MB:

+      if (parse_eth_header(packet, size, &eth)) {

+        fprintf(stderr, "error parsing eth header\n");

+        return;

+      }

+      fprintf(stderr, "  eth 0x%04x", eth.type);

+      fprintf(stderr, " %02x:%02x:%02x:%02x:%02x:%02x ->",

+              eth.src[0], eth.src[1], eth.src[2],

+              eth.src[3], eth.src[4], eth.src[5]);

+      fprintf(stderr, " %02x:%02x:%02x:%02x:%02x:%02x\n",

+              eth.dst[0], eth.dst[1], eth.dst[2],

+              eth.dst[3], eth.dst[4], eth.dst[5]);

+      if (eth.type != 0x0800) {

+        fprintf(stderr, "skipping packet: no IPv4\n");

+        return;

+      }

+      packet += ETH_HEADER_LEN;

+      size -= ETH_HEADER_LEN;

+      break;

+    case DLT_NULL:

+      if (parse_loop_header(packet, size, &loop)) {

+        fprintf(stderr, "error parsing loopback header\n");

+        return;

+      }

+      fprintf(stderr, " loopback family %d\n", loop.family);

+      if (loop.family != PF_INET) {

+        fprintf(stderr, "skipping packet: not IP\n");

+        return;

+      }

+      packet += LOOP_HEADER_LEN;

+      size -= LOOP_HEADER_LEN;

+      break;

+    default:

+      fprintf(stderr, "skipping packet: unrecognized linktype %d\n",

+          params->linktype);

+      return;

   }

-  fprintf(stderr, "  eth 0x%04x", eth.type);

-  fprintf(stderr, " %02x:%02x:%02x:%02x:%02x:%02x ->",

-          eth.src[0], eth.src[1], eth.src[2],

-          eth.src[3], eth.src[4], eth.src[5]);

-  fprintf(stderr, " %02x:%02x:%02x:%02x:%02x:%02x\n",

-          eth.dst[0], eth.dst[1], eth.dst[2],

-          eth.dst[3], eth.dst[4], eth.dst[5]);

-  packet += ETH_HEADER_LEN;

-  size -= ETH_HEADER_LEN;

-#elif LOOP

-  if (parse_loop_header(packet, size, &loop)) {

-    fprintf(stderr, "error parsing loopback header\n");

-    return;

-  }

-  fprintf(stderr, "  loopback family %d\n", loop.family);

-  packet += LOOP_HEADER_LEN;

-  size -= LOOP_HEADER_LEN;

-#endif

   if (parse_ip_header(packet, size, &ip)) {

     fprintf(stderr, "error parsing ip header\n");

@@ -667,6 +684,10 @@

   fprintf(stderr, " %d.%d.%d.%d",

           ip.dst[0], ip.dst[1], ip.dst[2], ip.dst[3]);

   fprintf(stderr, " header %d bytes\n", ip.header_size);

+  if (ip.protocol != 17) {

+    fprintf(stderr, "skipping packet: not UDP\n");

+    return;

+  }

   packet += ip.header_size;

   size -= ip.header_size;

@@ -740,11 +761,13 @@

     fprintf(stderr, "Couldn't open device %s: %s\n", device, errbuf);

     return(2);

   }

+  fprintf(stderr, "pcap datalink type is %d\n", pcap_datalink(pcap));

   params = malloc(sizeof(state));

   if (!params) {

     fprintf(stderr, "Couldn't allocate param struct.\n");

     return -1;

   }

+  params->linktype = pcap_datalink(pcap);

   params->stream = malloc(sizeof(ogg_stream_state));

   if (!params->stream) {

     fprintf(stderr, "Couldn't allocate stream struct.\n");