diff options
Diffstat (limited to 'contrib/tcpdump/print-vjc.c')
| -rw-r--r-- | contrib/tcpdump/print-vjc.c | 55 |
1 files changed, 46 insertions, 9 deletions
diff --git a/contrib/tcpdump/print-vjc.c b/contrib/tcpdump/print-vjc.c index 4283da6..f1877f2 100644 --- a/contrib/tcpdump/print-vjc.c +++ b/contrib/tcpdump/print-vjc.c @@ -24,17 +24,12 @@ #endif #ifndef lint -static const char rcsid[] = - "@(#) $Header: /tcpdump/master/tcpdump/print-vjc.c,v 1.9 2000/10/09 01:53:21 guy Exp $ (LBL)"; +static const char rcsid[] _U_ = + "@(#) $Header: /tcpdump/master/tcpdump/print-vjc.c,v 1.11.2.3 2003/11/19 01:09:12 guy Exp $ (LBL)"; #endif -#include <sys/param.h> -#include <sys/time.h> +#include <tcpdump-stdinc.h> -#include <netinet/in.h> - -#include <ctype.h> -#include <netdb.h> #include <pcap.h> #include <stdio.h> @@ -44,8 +39,50 @@ static const char rcsid[] = #include "slcompress.h" #include "ppp.h" +/* + * XXX - for BSD/OS PPP, what packets get supplied with a PPP header type + * of PPP_VJC and what packets get supplied with a PPP header type of + * PPP_VJNC? PPP_VJNC is for "UNCOMPRESSED_TCP" packets, and PPP_VJC + * is for COMPRESSED_TCP packets (PPP_IP is used for TYPE_IP packets). + * + * RFC 1144 implies that, on the wire, the packet type is *not* needed + * for PPP, as different PPP protocol types can be used; it only needs + * to be put on the wire for SLIP. + * + * It also indicates that, for compressed SLIP: + * + * If the COMPRESSED_TCP bit is set in the first byte, it's + * a COMPRESSED_TCP packet; that byte is the change byte, and + * the COMPRESSED_TCP bit, 0x80, isn't used in the change byte. + * + * If the upper 4 bits of the first byte are 7, it's an + * UNCOMPRESSED_TCP packet; that byte is the first byte of + * the UNCOMPRESSED_TCP modified IP header, with a connection + * number in the protocol field, and with the version field + * being 7, not 4. + * + * Otherwise, the packet is an IPv4 packet (where the upper 4 bits + * of the packet are 4). + * + * So this routine looks as if it's sort-of intended to handle + * compressed SLIP, although it doesn't handle UNCOMPRESSED_TCP + * correctly for that (it doesn't fix the version number and doesn't + * do anything to the protocol field), and doesn't check for COMPRESSED_TCP + * packets correctly for that (you only check the first bit - see + * B.1 in RFC 1144). + * + * But it's called for BSD/OS PPP, not SLIP - perhaps BSD/OS does weird + * things with the headers? + * + * Without a BSD/OS VJC-compressed PPP trace, or knowledge of what the + * BSD/OS VJC code does, we can't say what's the case. + * + * We therefore leave "proto" - which is the PPP protocol type - in place, + * *not* marked as unused, for now, so that GCC warnings about the + * unused argument remind us that we should fix this some day. + */ int -vjc_print(register const char *bp, register u_int length, u_short proto) +vjc_print(register const char *bp, u_short proto) { int i; |
