IPv6: Use ipv6_pinfo_t instead of ws_ip to keep some state

To perform IPv6 defragmentation we need to compute the IPv6 fragment header
payload length by subtracting the length of intermediate extension headers
from the IPv6 payload length.

Add a new frag_plen field to ipv6_pinfo_t to do that instead of (ab)using
struct ws_ip.

Note: The RFC 2460 rules for fragment header order are stricter than the code
suggests but that shouldn't be a problem here.

Change-Id: I76f3cb3a1a29d96b080d3d53c0f493f9d0b2786c
Reviewed-on: https://code.wireshark.org/review/16637
Petri-Dish: João Valverde <j@v6e.pt>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: João Valverde <j@v6e.pt>

diff --git a/epan/dissectors/packet-ip.h b/epan/dissectors/packet-ip.h
index adb84a0e5fe4ec080f54191e2e009d3a428b93a8..04ac8b07163766c72e57d3b0885f5786567ba8b8 100644 (file)
--- a/epan/dissectors/packet-ip.h
+++ b/epan/dissectors/packet-ip.h
@@ -33,7 +33,7 @@ typedef struct _ws_ip
     guint8  ip_ver;     /* 4 or 6 */
     guint8  ip_tos;     /* IPv4: type of service;   IPv6: traffic class */
     guint32 ip_flw;     /* IPv4: (zero);            IPv6: flow label */
-    guint32 ip_len;     /* IPv4: total length;      IPv6: payload length (minus extensions) */
+    guint32 ip_len;     /* IPv4: total length;      IPv6: payload length */
     guint16 ip_id;      /* IPv4: identification;    IPv6: (zero) */
     guint16 ip_off;     /* IPv4: fragment offset;   IPv6: (zero) */
     guint8  ip_ttl;     /* IPv4: time-to-live;      IPv6: hop limit */

diff --git a/epan/dissectors/packet-ipsec.c b/epan/dissectors/packet-ipsec.c
index 7998af1a03d8934581f53b7283bcd933fb848342..853ad5251a05f3b40baacfd13acf1b57b565a72c 100644 (file)
--- a/epan/dissectors/packet-ipsec.c
+++ b/epan/dissectors/packet-ipsec.c
@@ -1099,7 +1099,6 @@ dissect_ah(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data)
   tvbuff_t   *next_tvb;
   dissector_handle_t dissector_handle;
   guint32 saved_match_uint;
-  ws_ip *iph = (ws_ip *)data;
 
   col_set_str(pinfo->cinfo, COL_PROTOCOL, "AH");
   col_clear(pinfo->cinfo, COL_INFO);
@@ -1113,6 +1112,7 @@ dissect_ah(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data)
   if (pinfo->dst.type == AT_IPv6) {
     ipv6_pinfo_t *ipv6_pinfo = p_get_ipv6_pinfo(pinfo);
 
+    ipv6_pinfo->frag_plen -= ah_hdr_len;
     if (ipv6_pinfo->ipv6_tree != NULL) {
       root_tree = ipv6_pinfo->ipv6_tree;
       ipv6_pinfo->ipv6_item_len += ah_hdr_len;
@@ -1137,13 +1137,8 @@ dissect_ah(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data)
 
   next_tvb = tvb_new_subset_remaining(tvb, ah_hdr_len);
 
-  if (iph != NULL) {
-      iph->ip_nxt = ah_nxt;
-      iph->ip_len -= ah_hdr_len;
-  }
-
   if (pinfo->dst.type == AT_IPv6) {
-    ipv6_dissect_next(ah_nxt, next_tvb, pinfo, tree, iph);
+    ipv6_dissect_next(ah_nxt, next_tvb, pinfo, tree, (ws_ip *)data);
   } else {
     /* do lookup with the subdissector table */
     saved_match_uint  = pinfo->match_uint;

diff --git a/epan/dissectors/packet-ipv6.c b/epan/dissectors/packet-ipv6.c
index 2c16ed5c8921935f8253da35ec0ada70fd8b5721..10e3c1e700d17027a1bb9f900c8cced4012f1c51 100644 (file)
--- a/epan/dissectors/packet-ipv6.c
+++ b/epan/dissectors/packet-ipv6.c
@@ -1097,7 +1097,6 @@ dissect_routing6(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data
     int                offset = 0;
     tvbuff_t          *next_tvb;
     ipv6_pinfo_t      *ipv6_pinfo = p_get_ipv6_pinfo(pinfo);
-    ws_ip             *iph = (ws_ip *)data;
 
     col_append_sep_str(pinfo->cinfo, COL_INFO, " , ", "IPv6 routing");
 
@@ -1105,6 +1104,7 @@ dissect_routing6(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data
     len = (rt.ip6r_len + 1) << 3;
 
     root_tree = tree;
+    ipv6_pinfo->frag_plen -= len;
     if (ipv6_pinfo->ipv6_tree != NULL) {
         root_tree = ipv6_pinfo->ipv6_tree;
         ipv6_pinfo->ipv6_item_len += len;
@@ -1152,12 +1152,8 @@ dissect_routing6(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data
         break;
     }
 
-    if (iph != NULL) {
-        iph->ip_nxt = rt.ip6r_nxt;
-        iph->ip_len -= len;
-    }
     next_tvb = tvb_new_subset_remaining(tvb, len);
-    ipv6_dissect_next(rt.ip6r_nxt, next_tvb, pinfo, tree, iph);
+    ipv6_dissect_next(rt.ip6r_nxt, next_tvb, pinfo, tree, (ws_ip *)data);
     return tvb_captured_length(tvb);
 }
 
@@ -1175,7 +1171,6 @@ dissect_fraghdr(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
     gboolean         show_data = FALSE;
     gboolean         reassembled;
     tvbuff_t        *next_tvb;
-    ws_ip           *iph = (ws_ip *)data;
 
     nxt = tvb_get_guint8(tvb, offset);
     offlg = tvb_get_ntohs(tvb, offset + 2);
@@ -1186,6 +1181,7 @@ dissect_fraghdr(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
                         frag_off, frag_flg ? "y" : "n", frag_ident, nxt);
 
     root_tree = tree;
+    ipv6_pinfo->frag_plen -= 8;
     if (ipv6_pinfo->ipv6_tree != NULL) {
         root_tree = ipv6_pinfo->ipv6_tree;
         ipv6_pinfo->ipv6_item_len += 8;
@@ -1216,9 +1212,9 @@ dissect_fraghdr(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
     proto_tree_add_item(frag_tree, hf_ipv6_fraghdr_ident, tvb, offset, 4, ENC_BIG_ENDIAN);
     offset += 4;
 
-    if (iph != NULL) {
+    if (ipv6_pinfo->frag_plen > 0) {
         if ((frag_off != 0) || frag_flg) {
-            reassembled = ipv6_reassemble_do(&tvb, &offset, pinfo, frag_tree, iph->ip_len - 8,
+            reassembled = ipv6_reassemble_do(&tvb, &offset, pinfo, frag_tree, ipv6_pinfo->frag_plen,
                                              frag_off, frag_flg, frag_ident, &show_data);
             if (show_data) {
                 next_tvb = tvb_new_subset_remaining(tvb, offset);
@@ -1226,19 +1222,16 @@ dissect_fraghdr(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
                 return tvb_captured_length(tvb);
             }
             if (reassembled) {
-                iph->ip_nxt = nxt;
+                ipv6_pinfo->frag_plen = 0;
                 next_tvb = tvb_new_subset_remaining(tvb, offset);
-                iph->ip_len = tvb_reported_length_remaining(next_tvb, 0);
-                ipv6_dissect_next(nxt, next_tvb, pinfo, tree, iph);
+                ipv6_dissect_next(nxt, next_tvb, pinfo, tree, (ws_ip *)data);
                 return tvb_captured_length(tvb);
             }
         }
-
-        iph->ip_nxt = nxt;
-        iph->ip_len -= 8;
     }
+
     next_tvb = tvb_new_subset_remaining(tvb, offset);
-    ipv6_dissect_next(nxt, next_tvb, pinfo, tree, iph);
+    ipv6_dissect_next(nxt, next_tvb, pinfo, tree, (ws_ip *)data);
     return tvb_captured_length(tvb);
 }
 
@@ -1687,6 +1680,7 @@ dissect_opts(tvbuff_t *tvb, int offset, proto_tree *tree, packet_info *pinfo, ws
     offset_end = offset + len;
 
     root_tree = tree;
+    ipv6_pinfo->frag_plen -= len;
     if (ipv6_pinfo->ipv6_tree != NULL) {
         root_tree = ipv6_pinfo->ipv6_tree;
         ipv6_pinfo->ipv6_item_len += len;
@@ -1832,10 +1826,6 @@ dissect_opts(tvbuff_t *tvb, int offset, proto_tree *tree, packet_info *pinfo, ws
         }
     }
 
-    if (iph != NULL) {
-        iph->ip_nxt = nxt;
-        iph->ip_len -= len;
-    }
     next_tvb = tvb_new_subset_remaining(tvb, len);
     ipv6_dissect_next(nxt, next_tvb, pinfo, tree, iph);
     return tvb_captured_length(tvb);
@@ -2184,6 +2174,7 @@ dissect_ipv6(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_
 
     ipv6_pinfo->jumbo_plen = 0;
     ipv6_pinfo->ip6_plen = g_ntohs(ipv6->ip6_plen);
+    ipv6_pinfo->frag_plen = ipv6_pinfo->ip6_plen;
     if (!ipv6_exthdr_under_root) {
         ipv6_pinfo->ipv6_tree = ipv6_tree;
         ipv6_pinfo->ipv6_item_len = IPv6_HDR_SIZE;

diff --git a/epan/dissectors/packet-ipv6.h b/epan/dissectors/packet-ipv6.h
index fdac35e8ab4dd5dc4be7f1c64e017c0dc50c8a5f..1ddccadaae615b8e3372b4ce2722d87076ade229 100644 (file)
--- a/epan/dissectors/packet-ipv6.h
+++ b/epan/dissectors/packet-ipv6.h
@@ -106,6 +106,7 @@ extern "C" {
 typedef struct {
     guint32     jumbo_plen;
     guint16     ip6_plen;
+    gint        frag_plen;
     proto_tree *ipv6_tree;
     gint        ipv6_item_len;
 } ipv6_pinfo_t;

diff --git a/epan/dissectors/packet-mip6.c b/epan/dissectors/packet-mip6.c
index b6adb249e861876d24ae28d6730b8662a6f70d18..be33258bb094a674e93ac072c0b622a45bdf060a 100644 (file)
--- a/epan/dissectors/packet-mip6.c
+++ b/epan/dissectors/packet-mip6.c
@@ -4067,7 +4067,6 @@ dissect_mip6(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
     guint       len, offset = 0, start_offset = offset;
     proto_item *ti, *header_item;
     tvbuff_t   *next_tvb;
-    ws_ip      *iph = (ws_ip *)data;
 
     /* Make entries in Protocol column and Info column on summary display */
     col_set_str(pinfo->cinfo, COL_PROTOCOL, "MIPv6");
@@ -4080,6 +4079,7 @@ dissect_mip6(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
     if (pinfo->dst.type == AT_IPv6) {
         ipv6_pinfo_t *ipv6_pinfo = p_get_ipv6_pinfo(pinfo);
 
+        ipv6_pinfo->frag_plen -= len;
         if (ipv6_pinfo->ipv6_tree != NULL) {
             root_tree = ipv6_pinfo->ipv6_tree;
             ipv6_pinfo->ipv6_item_len += len;
@@ -4215,31 +4215,16 @@ dissect_mip6(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
         dissect_mip6_options(tvb, mip6_tree, offset, len, pinfo);
     }
 
-    /*
-     * XXX - why are we doing this?  We're not guaranteed that there's
-     * a ws_ip structure to modify here, as we can be called not only
-     * from the IPv4 or IPv6 dissectors, but also from, for example,
-     * the AH and ESP dissectors.
-     *
-     * This needs to be rethought.
-     */
-    if (iph != NULL)
-        iph->ip_nxt = pproto;
-
     if ((type == MIP6_FNA) && (pproto == IP_PROTO_IPV6)) {
         col_set_str(pinfo->cinfo, COL_INFO, "Fast Neighbor Advertisement[Fast Binding Update]");
         next_tvb = tvb_new_subset_remaining(tvb, len + 8);
-        if (iph != NULL)
-            iph->ip_len -= len + 8;
-        ipv6_dissect_next(pproto, next_tvb, pinfo, tree, iph);
+        ipv6_dissect_next(pproto, next_tvb, pinfo, tree, (ws_ip *)data);
     }
 
     if ((type == MIP6_FBACK) && (pproto == IP_PROTO_AH)) {
         col_set_str(pinfo->cinfo, COL_INFO, "Fast Binding Acknowledgment");
         next_tvb = tvb_new_subset_remaining(tvb, len + offset);
-        if (iph != NULL)
-            iph->ip_len -= len + offset;
-        ipv6_dissect_next(pproto, next_tvb, pinfo, tree, iph);
+        ipv6_dissect_next(pproto, next_tvb, pinfo, tree, (ws_ip *)data);
     }
 
     return tvb_captured_length(tvb);

diff --git a/epan/dissectors/packet-shim6.c b/epan/dissectors/packet-shim6.c
index e439a2c5b4d9ee1b8f814b0a2eeb217b8fd549e9..fe9b3fb575d7a54f7204b7e7f3dcc8830427ac2c 100644 (file)
--- a/epan/dissectors/packet-shim6.c
+++ b/epan/dissectors/packet-shim6.c
@@ -572,7 +572,6 @@ dissect_shim6(tvbuff_t *tvb, packet_info * pinfo, proto_tree *tree, void* data)
     proto_item      *ti, *ti_len;
     guint8           tmp[5];
     tvbuff_t        *next_tvb;
-    ws_ip           *iph = (ws_ip *)data;
 
     tvb_memcpy(tvb, (guint8 *)&shim, offset, sizeof(shim));
     len = (shim.ip6s_len + 1) << 3;
@@ -589,6 +588,7 @@ dissect_shim6(tvbuff_t *tvb, packet_info * pinfo, proto_tree *tree, void* data)
     if (pinfo->dst.type == AT_IPv6) {
         ipv6_pinfo_t *ipv6_pinfo = p_get_ipv6_pinfo(pinfo);
 
+        ipv6_pinfo->frag_plen -= len;
         if (ipv6_pinfo->ipv6_tree != NULL) {
             root_tree = ipv6_pinfo->ipv6_tree;
             ipv6_pinfo->ipv6_item_len += len;
@@ -663,12 +663,8 @@ dissect_shim6(tvbuff_t *tvb, packet_info * pinfo, proto_tree *tree, void* data)
         }
     }
 
-    if (iph != NULL) {
-        iph->ip_nxt = shim.ip6s_nxt;
-        iph->ip_len -= len;
-    }
     next_tvb = tvb_new_subset_remaining(tvb, len);
-    ipv6_dissect_next(shim.ip6s_nxt, next_tvb, pinfo, tree, iph);
+    ipv6_dissect_next(shim.ip6s_nxt, next_tvb, pinfo, tree, (ws_ip *)data);
     return tvb_captured_length(tvb);
 }