Hi,
I modified PPTP & GRE related codes. What I've done are:
o As per http://www.isi.edu/in-notes/iana/assignments/ethernet-numbers,
0x880b should be defined as ETHERTYPE_PPP, not ETHERTYPE_PPTP.
o PPTP is now identified by GRE Version Number of 1.
o Key field is now decoded as Payload length and Call ID in case of
PPTP.
o Checksum and Offset are now decoded if present.
o In general, length, checksum, offset are not a concern. So they
are printed in -vv (or more verbose) case. Version number, Key,
Call ID (in PPTP case), Sequence Number, Acknowledge Number
(in PPTP case) are now printed by default.
o Got rid of most part of struct gre, because they are not actually
used in the code.
=--=--=--=--=--=--=--=--=--=--=--=--=--=--=--=--=
+----+----+
|.. .| | Motonori Shindo
|_~__| |
| .. |~~_~| Sr. Systems Engineer
| . | | CoSine Communications Inc.
+----+----+
C o S i n e e-mail: [EMAIL PROTECTED]
Communications
=--=--=--=--=--=--=--=--=--=--=--=--=--=--=--=--=
Index: ethertype.h
===================================================================
RCS file: /tcpdump/master/tcpdump/ethertype.h,v
retrieving revision 1.13
diff -c -r1.13 ethertype.h
*** ethertype.h 2001/02/04 02:19:23 1.13
--- ethertype.h 2001/03/11 15:39:41
***************
*** 102,109 ****
#ifndef ETHERTYPE_IPV6
#define ETHERTYPE_IPV6 0x86dd
#endif
! #ifndef ETHERTYPE_PPTP
! #define ETHERTYPE_PPTP 0x880b
#endif
#ifndef ETHERTYPE_PPPOED
#define ETHERTYPE_PPPOED 0x8863
--- 102,109 ----
#ifndef ETHERTYPE_IPV6
#define ETHERTYPE_IPV6 0x86dd
#endif
! #ifndef ETHERTYPE_PPP
! #define ETHERTYPE_PPP 0x880b
#endif
#ifndef ETHERTYPE_PPPOED
#define ETHERTYPE_PPPOED 0x8863
Index: print-ether.c
===================================================================
RCS file: /tcpdump/master/tcpdump/print-ether.c,v
retrieving revision 1.62
diff -c -r1.62 print-ether.c
*** print-ether.c 2001/02/04 02:19:23 1.62
--- print-ether.c 2001/03/11 15:39:42
***************
*** 226,233 ****
pppoe_print(p, length);
return (1);
! case ETHERTYPE_PPTP:
! printf("pptp");
if (length) {
printf(": ");
ppp_print(p, length);
--- 226,233 ----
pppoe_print(p, length);
return (1);
! case ETHERTYPE_PPP:
! printf("ppp");
if (length) {
printf(": ");
ppp_print(p, length);
Index: print-gre.c
===================================================================
RCS file: /tcpdump/master/tcpdump/print-gre.c,v
retrieving revision 1.10
diff -c -r1.10 print-gre.c
*** print-gre.c 2001/02/03 20:21:28 1.10
--- print-gre.c 2001/03/11 15:39:43
***************
*** 45,75 ****
#include "addrtoname.h"
#include "extract.h" /* must come after interface.h */
- #define GRE_SIZE (20)
-
struct gre {
! u_short flags;
! u_short proto;
! union {
! struct gre_ckof {
! u_short cksum;
! u_short offset;
! } gre_ckof;
! u_int32_t key;
! u_int32_t seq;
! } gre_void1;
! union {
! u_int32_t key;
! u_int32_t seq;
! u_int32_t routing;
! } gre_void2;
! union {
! u_int32_t seq;
! u_int32_t routing;
! } gre_void3;
! union {
! u_int32_t routing;
! } gre_void4;
};
/* RFC 2784 - GRE */
--- 45,53 ----
#include "addrtoname.h"
#include "extract.h" /* must come after interface.h */
struct gre {
! u_int16_t flags;
! u_int16_t proto;
};
/* RFC 2784 - GRE */
***************
*** 85,90 ****
--- 63,69 ----
#define GRE_sP 0x0800 /* strict source route present */
#define GRE_RECUR_MASK 0x0700 /* Recursion Control */
#define GRE_RECUR_SHIFT 8
+ #define GRE_OP 0xc000 /* Offset Present */
/* "Enhanced GRE" from RFC2637 - PPTP */
#define GRE_AP 0x0080 /* Ack present */
***************
*** 93,107 ****
/*
* Deencapsulate and print a GRE-tunneled IP datagram
- *
- * XXX PPTP needs to interpret the "key" field...
*/
void
gre_print(const u_char *bp, u_int length)
{
const u_char *cp = bp + 4;
const struct gre *gre;
! u_short flags, proto, extracted_ethertype;
gre = (const struct gre *)bp;
--- 72,86 ----
/*
* Deencapsulate and print a GRE-tunneled IP datagram
*/
void
gre_print(const u_char *bp, u_int length)
{
const u_char *cp = bp + 4;
const struct gre *gre;
! u_int16_t flags, proto;
! u_short ver=0;
! u_short extracted_ethertype;
gre = (const struct gre *)bp;
***************
*** 126,163 ****
putchar('A');
if (flags & GRE_RECUR_MASK)
printf("R%x", (flags & GRE_RECUR_MASK) >> GRE_RECUR_SHIFT);
! if (flags & GRE_VER_MASK)
! printf("v%x", flags & GRE_VER_MASK);
if (flags & GRE_MBZ_MASK)
printf("!%x", flags & GRE_MBZ_MASK);
fputs("] ", stdout);
}
- /* Checksum & Offset are present */
- if ((flags & GRE_CP) | (flags & GRE_RP))
- cp += 4;
-
- /* We don't support routing fields (variable length) now. Punt. */
- if (flags & GRE_RP)
- return;
! if (flags & GRE_KP) {
TCHECK2(*cp, 4);
if (vflag > 1)
printf("K:%08x ", EXTRACT_32BITS(cp));
cp += 4; /* skip key */
}
if (flags & GRE_SP) {
TCHECK2(*cp, 4);
! if (vflag > 1)
! printf("S:%08x ", EXTRACT_32BITS(cp));
cp += 4; /* skip seq */
}
! if (flags & GRE_AP && (flags & GRE_VER_MASK) >= 1) {
TCHECK2(*cp, 4);
! if (vflag > 1)
! printf("A:%08x ", EXTRACT_32BITS(cp));
cp += 4; /* skip ack */
}
TCHECK(cp[0]);
--- 105,154 ----
putchar('A');
if (flags & GRE_RECUR_MASK)
printf("R%x", (flags & GRE_RECUR_MASK) >> GRE_RECUR_SHIFT);
! ver = flags & GRE_VER_MASK;
! printf("v%u", ver);
!
if (flags & GRE_MBZ_MASK)
printf("!%x", flags & GRE_MBZ_MASK);
fputs("] ", stdout);
}
! if (flags & GRE_CP) {
! TCHECK2(*cp, 4);
! if (vflag > 1)
! printf("C:%08x ", EXTRACT_32BITS(cp));
! cp += 4; /* skip checksum */
! }
! if (flags & GRE_OP) {
TCHECK2(*cp, 4);
if (vflag > 1)
+ printf("O:%08x ", EXTRACT_32BITS(cp));
+ cp += 4; /* skip offset */
+ }
+ if (flags & GRE_KP) {
+ TCHECK2(*cp, 4);
+ if (ver == 1) { /* PPTP */
+ if (vflag > 1)
+ printf("PL:%u ", EXTRACT_16BITS(cp));
+ printf("ID:%04x ", EXTRACT_16BITS(cp+2));
+ }
+ else
printf("K:%08x ", EXTRACT_32BITS(cp));
cp += 4; /* skip key */
}
if (flags & GRE_SP) {
TCHECK2(*cp, 4);
! printf("S:%u ", EXTRACT_32BITS(cp));
cp += 4; /* skip seq */
}
! if (flags & GRE_AP && ver >= 1) {
TCHECK2(*cp, 4);
! printf("A:%u ", EXTRACT_32BITS(cp));
cp += 4; /* skip ack */
}
+ /* We don't support routing fields (variable length) now. Punt. */
+ if (flags & GRE_RP)
+ return;
TCHECK(cp[0]);
