DNS: Sync types with IANA

[tcpdump] / netdissect.c

diff --git a/netdissect.c b/netdissect.c
index 7e46d6aa3d3176ede396fefee8c788d7a053db03..000d1ffce8c2c6eb9a47f36e9a79e0b5ec2b258e 100644 (file)
--- a/netdissect.c
+++ b/netdissect.c
@@ -149,7 +149,7 @@ nd_smi_version_string(void)
 
 int
 nd_push_buffer(netdissect_options *ndo, u_char *new_buffer,
-    const u_char *new_packetp, const u_char *new_snapend)
+              const u_char *new_packetp, const u_int newlen)
 {
        struct netdissect_saved_packet_info *ndspi;
 
@@ -162,20 +162,30 @@ nd_push_buffer(netdissect_options *ndo, u_char *new_buffer,
        ndspi->ndspi_prev = ndo->ndo_packet_info_stack;
 
        ndo->ndo_packetp = new_packetp;
-       ndo->ndo_snapend = new_snapend;
+       ndo->ndo_snapend = new_packetp + newlen;
        ndo->ndo_packet_info_stack = ndspi;
 
        return (1);     /* success */
 }
 
+
 /*
- * Set a new snapshot end to the minimum of the existing snapshot end
- * and the new snapshot end.
+ * In a given netdissect_options structure:
+ *
+ *    push the current packet information onto the packet information
+ *    stack;
+ *
+ *    given a pointer into the packet and a length past that point in
+ *    the packet, calculate a new snapshot end that's at the lower
+ *    of the current snapshot end and that point in the packet;
+ *
+ *    set the snapshot end to that new value.
  */
 int
-nd_push_snapend(netdissect_options *ndo, const u_char *new_snapend)
+nd_push_snaplen(netdissect_options *ndo, const u_char *bp, const u_int newlen)
 {
        struct netdissect_saved_packet_info *ndspi;
+       u_int snaplen_remaining;
 
        ndspi = (struct netdissect_saved_packet_info *)malloc(sizeof(struct netdissect_saved_packet_info));
        if (ndspi == NULL)
@@ -185,32 +195,87 @@ nd_push_snapend(netdissect_options *ndo, const u_char *new_snapend)
        ndspi->ndspi_snapend = ndo->ndo_snapend;
        ndspi->ndspi_prev = ndo->ndo_packet_info_stack;
 
-       /* No new packet pointer, either */
-       if (new_snapend < ndo->ndo_snapend)
-               ndo->ndo_snapend = new_snapend;
+       /*
+        * Push the saved previous data onto the stack.
+        */
        ndo->ndo_packet_info_stack = ndspi;
 
+       /*
+        * Find out how many bytes remain after the current snapend.
+        *
+        * We're restricted to packets with at most UINT_MAX bytes;
+        * cast the result to u_int, so that we don't get truncation
+        * warnings on LP64 and LLP64 platforms.  (ptrdiff_t is
+        * signed and we want an unsigned difference; the pointer
+        * should at most be equal to snapend, and must *never*
+        * be past snapend.)
+        */
+       snaplen_remaining = (u_int)(ndo->ndo_snapend - bp);
+
+       /*
+        * If the new snapend is smaller than the one calculated
+        * above, set the snapend to that value, otherwise leave
+        * it unchanged.
+        */
+       if (newlen <= snaplen_remaining) {
+               /* Snapend isn't past the previous snapend */
+               ndo->ndo_snapend = bp + newlen;
+       }
+
        return (1);     /* success */
 }
 
 /*
- * Change an already-pushed snapshot end.  This may increase the
+ * In a given netdissect_options structure:
+ *
+ *    given a pointer into the packet and a length past that point in
+ *    the packet, calculate a new snapshot end that's at the lower
+ *    of the previous snapshot end - or, if there is no previous
+ *    snapshot end, the current snapshot end - and that point in the
+ *    packet;
+ *
+ *    set the snapshot end to that new value.
+ *
+ * This is to change the current snapshot end.  This may increase the
  * snapshot end, as it may be used, for example, for a Jumbo Payload
  * option in IPv6.  It must not increase it past the snapshot length
  * atop which the current one was pushed, however.
  */
 void
-nd_change_snapend(netdissect_options *ndo, const u_char *new_snapend)
+nd_change_snaplen(netdissect_options *ndo, const u_char *bp, const u_int newlen)
 {
        struct netdissect_saved_packet_info *ndspi;
+       const u_char *previous_snapend;
+       u_int snaplen_remaining;
 
        ndspi = ndo->ndo_packet_info_stack;
-       if (ndspi->ndspi_prev != NULL) {
-               if (new_snapend <= ndspi->ndspi_prev->ndspi_snapend)
-                       ndo->ndo_snapend = new_snapend;
-       } else {
-               if (new_snapend < ndo->ndo_snapend)
-                       ndo->ndo_snapend = new_snapend;
+       if (ndspi->ndspi_prev != NULL)
+               previous_snapend = ndspi->ndspi_prev->ndspi_snapend;
+       else
+               previous_snapend = ndo->ndo_snapend;
+
+       /*
+        * Find out how many bytes remain after the previous
+        * snapend - or, if there is no previous snapend, after
+        * the current snapend.
+        *
+        * We're restricted to packets with at most UINT_MAX bytes;
+        * cast the result to u_int, so that we don't get truncation
+        * warnings on LP64 and LLP64 platforms.  (ptrdiff_t is
+        * signed and we want an unsigned difference; the pointer
+        * should at most be equal to snapend, and must *never*
+        * be past snapend.)
+        */
+       snaplen_remaining = (u_int)(previous_snapend - bp);
+
+       /*
+        * If the new snapend is smaller than the one calculated
+        * above, set the snapend to that value, otherwise leave
+        * it unchanged.
+        */
+       if (newlen <= snaplen_remaining) {
+               /* Snapend isn't past the previous snapend */
+               ndo->ndo_snapend = bp + newlen;
        }
 }