Added Richard Sharpe's TFTP support.

svn path=/trunk/; revision=190

1 files changed, 127 insertions, 8 deletions

diff --git a/packet-udp.c b/packet-udp.c
index 19c4a5018b..a5d6f86e78 100644
--- a/packet-udp.c
+++ b/packet-udp.c
@@ -1,12 +1,14 @@
 /* packet-udp.c
  * Routines for UDP packet disassembly
  *
- * $Id: packet-udp.c,v 1.11 1998/12/29 04:05:36 gerald Exp $
+ * $Id: packet-udp.c,v 1.12 1999/02/15 06:36:57 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@zing.org>
  * Copyright 1998 Gerald Combs
  *
+ * Richard Sharpe, 13-Feb-1999, added dispatch table support and 
+ *                              support for tftp.
  * 
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -43,10 +45,99 @@
 #include "packet.h"
 #include "resolv.h"
 
+struct hash_struct {
+  guint16 proto;
+  void (*dissect)(const u_char *, int, frame_data *, GtkTree *);
+  struct hash_struct *next;
+};
+
+struct hash_struct *hash_table[256];
+
+/*
+ * These routines are for UDP, will be generalized soon: RJS
+ *
+ * XXX - note that they should probably check the IP address as well as
+ * the port number, so that we don't mistakenly identify packets as, say,
+ * TFTP, merely because they have a source or destination port number
+ * equal to the port being used by a TFTP daemon on some machine other
+ * than the one they're going to or from.
+ */
+
+struct hash_struct *udp_find_hash_ent(guint16 proto) {
+
+  int idx = proto % 256;
+  struct hash_struct *hash_ent = hash_table[idx];
+
+  while (hash_ent != NULL) {
+
+    if (hash_ent -> proto == proto)
+      return hash_ent;
+  
+    hash_ent = hash_ent -> next;
+
+  }
+
+  return NULL;
+
+}
+
+void udp_hash_add(guint16 proto,
+	void (*dissect)(const u_char *, int, frame_data *, GtkTree *)) {
+
+  int idx = proto % 256;   /* Simply take the remainder, hope for no collisions */
+  struct hash_struct *hash_ent = (struct hash_struct *)malloc(sizeof(struct hash_struct));
+  struct hash_struct *hash_ent2;
+  
+  hash_ent -> proto = proto;
+  hash_ent -> dissect = dissect;
+  hash_ent -> next = NULL;
+
+  if (hash_ent == NULL) {
+
+    fprintf(stderr, "Could not allocate space for hash structure in dissect_udp\n");
+    exit(1);
+  }
+
+  if (hash_table[idx]) {  /* Something, add on end */
+
+    hash_ent2 = hash_table[idx];
+
+    while (hash_ent2 -> next != NULL)
+      hash_ent2 = hash_ent2 -> next;
+
+    hash_ent2 -> next = hash_ent;     /* Bad in pathalogical cases */
+
+  }
+  else {
+
+    hash_table[idx] = hash_ent;
+
+  }
+
+}
+
+void init_dissect_udp(void) {
+
+  int i;
+
+  for (i = 0; i < 256; i++) {
+
+    hash_table[i] = NULL;
+
+  }
+
+  /* Now add the protocols we know about */
+
+  udp_hash_add(UDP_PORT_BOOTPS, dissect_bootp);
+  udp_hash_add(UDP_PORT_TFTP, dissect_tftp);
+
+}
+
 void
 dissect_udp(const u_char *pd, int offset, frame_data *fd, GtkTree *tree) {
   e_udphdr  uh;
   guint16    uh_sport, uh_dport, uh_ulen, uh_sum;
+  struct hash_struct *dissect_routine = NULL;
   GtkWidget *udp_tree, *ti;
 
   /* To do: Check for {cap len,pkt len} < struct len */
@@ -99,12 +190,12 @@ dissect_udp(const u_char *pd, int offset, frame_data *fd, GtkTree *tree) {
       /* we should check the source port too (RIP: UDP src and dst port 520) */
       dissect_rip(pd, offset, fd, tree);
       break;
-	case UDP_PORT_NBNS:
-	  dissect_nbns(pd, offset, fd, tree);
-	  break;
-	case UDP_PORT_NBDGM:
-	  dissect_nbdgm(pd, offset, fd, tree);
-	  break;
+    case UDP_PORT_NBNS:
+      dissect_nbns(pd, offset, fd, tree);
+      break;
+    case UDP_PORT_NBDGM:
+      dissect_nbdgm(pd, offset, fd, tree);
+      break;
     case UDP_PORT_IPX: /* RFC 1234 */
       dissect_ipx(pd, offset, fd, tree);
       break;
@@ -112,7 +203,35 @@ dissect_udp(const u_char *pd, int offset, frame_data *fd, GtkTree *tree) {
       /* FIXME: AFAIK, src and dst port must be the same */
       dissect_vines_frp(pd, offset, fd, tree);
       break;
+    case UDP_PORT_TFTP:
+      /* This is the first point of call, but it adds a dynamic call */
+      udp_hash_add(MAX(uh_sport, uh_dport), dissect_tftp);  /* Add to table */
+      dissect_tftp(pd, offset, fd, tree);
+      break;
     default:
-      dissect_data(pd, offset, fd, tree);
+
+      /* OK, find a routine in the table, else use the default */
+
+      if ((dissect_routine = udp_find_hash_ent(uh_sport))) {
+
+	struct hash_struct *dr2 = udp_find_hash_ent(uh_dport);
+
+	if (dr2 == NULL) {  /* Not in the table, add */
+
+	  udp_hash_add(uh_dport, dissect_tftp);
+
+	}
+
+	dissect_routine -> dissect(pd, offset, fd, tree);
+      }
+      else if ((dissect_routine = udp_find_hash_ent(uh_dport))) {
+
+	dissect_routine -> dissect(pd, offset, fd, tree);
+
+      }
+      else {
+
+	dissect_data(pd, offset, fd, tree);
+      }
   }
 }