Don't run past the snapshot length when doing hex/ASCII dumps.

diff --git a/print-ascii.c b/print-ascii.c
index 96410da8faf65b5026dc63347a2b292f134b94c3..3cefef33aeb4f8578138e81e49e857b623aa3a9f 100644 (file)
--- a/print-ascii.c
+++ b/print-ascii.c
@@ -57,8 +57,12 @@ void
 ascii_print(netdissect_options *ndo,
             const u_char *cp, u_int length)
 {
+       u_int caplength;
        register u_char s;
 
+       caplength = (ndo->ndo_snapend >= cp) ? ndo->ndo_snapend - cp : 0;
+       if (length > caplength)
+               length = caplength;
        ND_PRINT((ndo, "\n"));
        while (length > 0) {
                s = *cp++;
@@ -89,12 +93,16 @@ void
 hex_and_ascii_print_with_offset(netdissect_options *ndo, register const char *ident,
     register const u_char *cp, register u_int length, register u_int oset)
 {
+       u_int caplength;
        register u_int i;
        register int s1, s2;
        register int nshorts;
        char hexstuff[HEXDUMP_SHORTS_PER_LINE*HEXDUMP_HEXSTUFF_PER_SHORT+1], *hsp;
        char asciistuff[ASCII_LINELENGTH+1], *asp;
 
+       caplength = (ndo->ndo_snapend >= cp) ? ndo->ndo_snapend - cp : 0;
+       if (length > caplength)
+               length = caplength;
        nshorts = length / sizeof(u_short);
        i = 0;
        hsp = hexstuff; asp = asciistuff;
@@ -147,9 +155,13 @@ hex_print_with_offset(netdissect_options *ndo,
                       const char *ident, const u_char *cp, u_int length,
                      u_int oset)
 {
+       u_int caplength;
        register u_int i, s;
        register int nshorts;
 
+       caplength = (ndo->ndo_snapend >= cp) ? ndo->ndo_snapend - cp : 0;
+       if (length > caplength)
+               length = caplength;
        nshorts = (u_int) length / sizeof(u_short);
        i = 0;
        while (--nshorts >= 0) {

diff --git a/tcpdump.c b/tcpdump.c
index 8d615d74cb8c2bbc3097521b855e5143193845bb..48c470000e9ce0c510dff0480e6e407841fad346 100644 (file)
--- a/tcpdump.c
+++ b/tcpdump.c
@@ -2303,7 +2303,8 @@ print_packet(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
        /*
         * Some printers want to check that they're not walking off the
         * end of the packet.
-        * Rather than pass it all the way down, we set this global.
+        * Rather than pass it all the way down, we set this member
+        * of the netdissect_options structure.
         */
        ndo->ndo_snapend = sp + h->caplen;
 
@@ -2313,6 +2314,11 @@ print_packet(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
                 hdrlen = (*print_info->p.printer)(h, sp);
         }
 
+       /*
+        * Restore the original snapend, as a printer might have
+        * changed it.
+        */
+       ndo->ndo_snapend = sp + h->caplen;
        if (ndo->ndo_Xflag) {
                /*
                 * Print the raw packet data in hex and ASCII.