Fetch RTP option and extension data using EXTRACT_32BITS().

Do not assume that you're on a big-endian processor that can dereference
unaligned pointers - all the world's not a m68k.  :-) Most of the world
is little-endian these days by CPU count (especially on personal
computers), and one of the popular big-endian processor families, SPARC,
traps when dereferencing unaligned pointers.

While we're at it, note the last I-D that described RTPv1 and the
current RFC for RTPv2.

diff --git a/print-udp.c b/print-udp.c
index 992b6c3bb7e0beafbdd7911717e77dfade39a947..4b5cd7c25055e9a51826853487714c0bd3ba7da1 100644 (file)
--- a/print-udp.c
+++ b/print-udp.c
@@ -135,13 +135,13 @@ rtp_print(netdissect_options *ndo, const void *hdr, u_int len,
        hasopt = 0;
        hasext = 0;
        if ((i0 >> 30) == 1) {
-               /* rtp v1 */
+               /* rtp v1 - draft-ietf-avt-rtp-04 */
                hasopt = i0 & 0x800000;
                contype = (i0 >> 16) & 0x3f;
                hasmarker = i0 & 0x400000;
                ptype = "rtpv1";
        } else {
-               /* rtp v2 */
+               /* rtp v2 - RFC 3550 */
                hasext = i0 & 0x10000000;
                contype = (i0 >> 16) & 0x7f;
                hasmarker = i0 & 0x800000;
@@ -163,7 +163,7 @@ rtp_print(netdissect_options *ndo, const void *hdr, u_int len,
                if (hasopt) {
                        u_int i2, optlen;
                        do {
-                               i2 = ip[0];
+                               i2 = EXTRACT_32BITS(ip);
                                optlen = (i2 >> 16) & 0xff;
                                if (optlen == 0 || optlen > len) {
                                        ND_PRINT((ndo, " !opt"));
@@ -175,7 +175,7 @@ rtp_print(netdissect_options *ndo, const void *hdr, u_int len,
                }
                if (hasext) {
                        u_int i2, extlen;
-                       i2 = ip[0];
+                       i2 = EXTRACT_32BITS(ip);
                        extlen = (i2 & 0xffff) + 1;
                        if (extlen > len) {
                                ND_PRINT((ndo, " !ext"));
@@ -184,7 +184,7 @@ rtp_print(netdissect_options *ndo, const void *hdr, u_int len,
                        ip += extlen;
                }
                if (contype == 0x1f) /*XXX H.261 */
-                       ND_PRINT((ndo, " 0x%04x", ip[0] >> 16));
+                       ND_PRINT((ndo, " 0x%04x", EXTRACT_32BITS(ip) >> 16));
        }
 }