Address Michael's comments.

[tcpdump] / print-pppoe.c

diff --git a/print-pppoe.c b/print-pppoe.c
index d7baa20d56e18639d282b483aa271ffa8a28edf0..bcc976c4b7981c768049978263bf417952f67ece 100644 (file)
--- a/print-pppoe.c
+++ b/print-pppoe.c
@@ -23,7 +23,7 @@
 
 #ifndef lint
 static const char rcsid[] _U_ =
-"@(#) $Header: /tcpdump/master/tcpdump/print-pppoe.c,v 1.29 2004-08-27 03:28:58 guy Exp $ (LBL)";
+"@(#) $Header: /tcpdump/master/tcpdump/print-pppoe.c,v 1.31 2005-04-26 19:48:38 guy Exp $ (LBL)";
 #endif
 
 #ifdef HAVE_CONFIG_H
@@ -70,6 +70,7 @@ enum {
        PPPOE_AC_COOKIE = 0x0104,
        PPPOE_VENDOR = 0x0105,
        PPPOE_RELAY_SID = 0x0110,
+       PPPOE_MAX_PAYLOAD = 0x0120,
        PPPOE_SERVICE_NAME_ERROR = 0x0201,
        PPPOE_AC_SYSTEM_ERROR = 0x0202,
        PPPOE_GENERIC_ERROR = 0x0203
@@ -83,6 +84,7 @@ static struct tok pppoetag2str[] = {
        { PPPOE_AC_COOKIE, "AC-Cookie" },
        { PPPOE_VENDOR, "Vendor-Specific" },
        { PPPOE_RELAY_SID, "Relay-Session-ID" },
+       { PPPOE_MAX_PAYLOAD, "PPP-Max-Payload" },
        { PPPOE_SERVICE_NAME_ERROR, "Service-Name-Error" },
        { PPPOE_AC_SYSTEM_ERROR, "AC-System-Error" },
        { PPPOE_GENERIC_ERROR, "Generic-Error" },
@@ -101,9 +103,15 @@ pppoe_if_print(const struct pcap_pkthdr *h, register const u_char *p)
 u_int
 pppoe_print(register const u_char *bp, u_int length)
 {
-       u_short pppoe_ver, pppoe_type, pppoe_code, pppoe_sessionid, pppoe_length;
+       u_int16_t pppoe_ver, pppoe_type, pppoe_code, pppoe_sessionid;
+       u_int pppoe_length;
        const u_char *pppoe_packet, *pppoe_payload;
 
+       if (length < PPPOE_HDRLEN) {
+               (void)printf("truncated-pppoe %u", length);
+               return (length);
+       }
+       length -= PPPOE_HDRLEN;
        pppoe_packet = bp;
        TCHECK2(*pppoe_packet, PPPOE_HDRLEN);
        pppoe_ver  = (pppoe_packet[0] & 0xF0) >> 4;
@@ -113,11 +121,6 @@ pppoe_print(register const u_char *bp, u_int length)
        pppoe_length    = EXTRACT_16BITS(pppoe_packet + 4);
        pppoe_payload = pppoe_packet + PPPOE_HDRLEN;
 
-       if (snapend < pppoe_payload) {
-               printf(" truncated PPPoE");
-               return (PPPOE_HDRLEN);
-       }
-
        if (pppoe_ver != 1) {
                printf(" [ver %d]",pppoe_ver);
        }
@@ -127,27 +130,16 @@ pppoe_print(register const u_char *bp, u_int length)
 
        printf("PPPoE %s", tok2str(pppoecode2str, "PAD-%x", pppoe_code));
        if (pppoe_code == PPPOE_PADI && pppoe_length > 1484 - PPPOE_HDRLEN) {
-               printf(" [len %d!]",pppoe_length);
+               printf(" [len %u!]",pppoe_length);
+       }
+       if (pppoe_length > length) {
+               printf(" [len %u > %u!]", pppoe_length, length);
+               pppoe_length = length;
        }
        if (pppoe_sessionid) {
                printf(" [ses 0x%x]", pppoe_sessionid);
        }
 
-       if (pppoe_payload + pppoe_length < snapend && snapend-pppoe_payload+14 > 64) {
-               /* (small packets are probably just padded up to the ethernet
-                  minimum of 64 bytes) */
-               printf(" [length %d (%d extra bytes)]",
-                   pppoe_length, snapend - pppoe_payload - pppoe_length);
-#if RESPECT_PAYLOAD_LENGTH
-               snapend = pppoe_payload+pppoe_length;
-#else
-               /* Actual PPPoE implementations appear to ignore the payload
-                  length and use the full ethernet frame anyways */
-               pppoe_length = snapend-pppoe_payload;
-#endif
-               
-       }
-
        if (pppoe_code) {
                /* PPP session packets don't contain tags */
                u_short tag_type = 0xffff, tag_len;
@@ -155,11 +147,10 @@ pppoe_print(register const u_char *bp, u_int length)
 
                /*
                 * loop invariant:
-                * p points to next tag,
+                * p points to current tag,
                 * tag_type is previous tag or 0xffff for first iteration
                 */
-               while (tag_type && p + 4 < pppoe_payload + length &&
-                   p + 4 < snapend) {
+               while (tag_type && p < pppoe_payload + pppoe_length) {
                        TCHECK2(*p, 4);
                        tag_type = EXTRACT_16BITS(p);
                        tag_len = EXTRACT_16BITS(p + 2);