Merge branch 'ip_offset-patch' into v1.1.2.1-forkv1.1.2.1-fork

11 files changed, 81 insertions, 294 deletions

diff --git a/.gitignore b/.gitignore
index 3d6dbf5..6395c86 100644
--- a/.gitignore
+++ b/.gitignore
@@ -61,6 +61,7 @@ libnet/sample/stp
 libnet/sample/synflood
 libnet/sample/synflood6
 libnet/sample/synflood6_frag
+libnet/sample/test_ipv4
 libnet/sample/tcp1
 libnet/sample/tcp2
 libnet/sample/tftp
diff --git a/libnet/include/libnet/libnet-functions.h b/libnet/include/libnet/libnet-functions.h
index c4fe599..99b1139 100644
--- a/libnet/include/libnet/libnet-functions.h
+++ b/libnet/include/libnet/libnet-functions.h
@@ -794,6 +794,7 @@ u_int8_t *payload, u_int32_t payload_s, libnet_t *l, libnet_ptag_t ptag);
 /**
  * Builds a version 4 RFC 791 Internet Protocol (IP) header.
  * @param len total length of the IP packet including all subsequent data
+ *   FIXME There is no reason this can't be calculated if zero is passed.
  * @param tos type of service bits
  * @param id IP identification number
  * @param frag fragmentation bits and offset
@@ -2080,10 +2081,10 @@ u_int8_t type);
   * Function updates referer used to compute the checksum. All
   * pblock need to know where is their referer (ie IP header).
   * So, this function is called each time a new IP header is inserted.
-  * It updates the ip_pos field (referer) of each subsequent pblock.
+  * It updates the ip_offset field (referer) of each previous pblock.
   */
 void
-libnet_pblock_record_ip_offset(libnet_t *l, u_int32_t offset);
+libnet_pblock_record_ip_offset(libnet_t *l, libnet_pblock_t *p);
 
 /*
  * [Internal] 
diff --git a/libnet/include/libnet/libnet-structures.h b/libnet/include/libnet/libnet-structures.h
index 38aff5d..eb7de76 100644
--- a/libnet/include/libnet/libnet-structures.h
+++ b/libnet/include/libnet/libnet-structures.h
@@ -79,8 +79,19 @@ struct libnet_protocol_block
     u_int8_t *buf;                      /* protocol buffer */
     u_int32_t b_len;                    /* length of buf */
     u_int16_t h_len;                    /* header length (for checksumming) */
-    u_int32_t ip_offset;                /* offset to IP header for csums */
-    u_int32_t copied;                   /* bytes copied */
+       /* Unused for IPV4_H block types.
+        * For protocols that sit on top of IP, it should be the the amount of
+        * buf that is the header, and will be included in the checksum.
+        */
+    u_int32_t ip_offset;                /* offset from end of pkt to beginning of IP header for csums */
+       /* Unused for IPV4_H block types.
+        * For protocols that sit on top of IP (UDP, ICMP, ...), they often
+        * include some information from the IP header (in the form of a "pseudo
+        * header") in their own checksum calculation. To build that
+        * pseudo-header, thet need to find the real header.
+        */
+    u_int32_t copied;                   /* bytes copied - the amount of data copied into buf */
+       /* Used and updated by libnet_pblock_append(). */
     u_int8_t type;                      /* type of pblock */
 /* this needs to be updated every time a new packet builder is added */
 #define LIBNET_PBLOCK_ARP_H             0x01    /* ARP header */
diff --git a/libnet/sample/Makefile.am b/libnet/sample/Makefile.am
index 05cccbb..87b76a7 100644
--- a/libnet/sample/Makefile.am
+++ b/libnet/sample/Makefile.am
@@ -14,7 +14,7 @@ noinst_PROGRAMS = arp cdp dhcp_discover get_addr icmp_timestamp icmp_unreach \
                   smurf dot1x dns rpc_tcp rpc_udp mpls icmp_timeexceed \
                   fddi_tcp1 fddi_tcp2 tring_tcp1 tring_tcp2 icmp_redirect \
                   bgp4_hdr bgp4_open bgp4_update bgp4_notification gre \
-                  synflood6_frag tftp ip_link ip_raw sebek
+                  synflood6_frag tftp ip_link ip_raw sebek test_ipv4 test_ipv6_icmpv4
 
 arp_SOURCES             = arp.c
 cdp_SOURCES             = cdp.c
@@ -59,5 +59,7 @@ gre_SOURCES		= gre.c
 ip_raw_SOURCES          = ip_raw.c
 ip_link_SOURCES		= ip_link.c
 sebek_SOURCES           = sebek.c
+test_ipv4_SOURCES       = test_ipv4.c
+test_ipv6_icmpv4_SOURCES = test_ipv6_icmpv4.c
 
 LDADD 			= $(top_srcdir)/src/libnet.la
diff --git a/unmerged/test_ipv4.c b/libnet/sample/test_ipv4.c
index cf1646b..cf1646b 100644
--- a/unmerged/test_ipv4.c
+++ b/libnet/sample/test_ipv4.c
diff --git a/unmerged/test_ipv6_icmpv4.c b/libnet/sample/test_ipv6_icmpv4.c
index b3dcd67..b3dcd67 100644
--- a/unmerged/test_ipv6_icmpv4.c
+++ b/libnet/sample/test_ipv6_icmpv4.c
diff --git a/libnet/src/libnet_build_ip.c b/libnet/src/libnet_build_ip.c
index 3d3675b..c23c296 100644
--- a/libnet/src/libnet_build_ip.c
+++ b/libnet/src/libnet_build_ip.c
@@ -45,7 +45,6 @@ libnet_build_ipv4(u_int16_t len, u_int8_t tos, u_int16_t id, u_int16_t frag,
 u_int8_t ttl, u_int8_t prot, u_int16_t sum, u_int32_t src, u_int32_t dst,
 u_int8_t *payload, u_int32_t payload_s, libnet_t *l, libnet_ptag_t ptag)
 {
-    int offset;
     u_int32_t h, n, i, j;
     libnet_pblock_t *p, *p_data, *p_temp;
     struct libnet_ipv4_hdr ip_hdr;
@@ -58,9 +57,12 @@ u_int8_t *payload, u_int32_t payload_s, libnet_t *l, libnet_ptag_t ptag)
 
     n = LIBNET_IPV4_H;                      /* size of memory block */
     h = len;                                /* header length */
+    // WRONG - this is total len of ip packet, and is put into the IP header
     ptag_data = 0;                          /* used if options are present */
+    // WRONG - is used if there is ipv4 payload
 
     if (h + payload_s > IP_MAXPACKET)
+    // WRONG - h is the total length, it already includes payload_s
     {
          snprintf(l->err_buf, LIBNET_ERRBUF_SIZE,
                 "%s(): IP packet too large\n", __func__);
@@ -97,6 +99,9 @@ u_int8_t *payload, u_int32_t payload_s, libnet_t *l, libnet_ptag_t ptag)
             ip_hdr.ip_hl += j;
         }
     }
+    // Note that p->h_len is not adjusted. This seems a bug, but it is because
+    // it is not used!  libnet_do_checksum() is passed the h_len (as `len'),
+    // but for IPPROTO_IP it is ignored in favor of the ip_hl.
 
     ip_hdr.ip_tos        = tos;                       /* IP tos */
     ip_hdr.ip_len        = htons(h);                  /* total length */
@@ -123,7 +128,10 @@ u_int8_t *payload, u_int32_t payload_s, libnet_t *l, libnet_ptag_t ptag)
     }
 
     /* find and set the appropriate ptag, or else use the default of 0 */
-    offset = payload_s;
+    /* When updating the ipv4 block, we need to find the data block, and
+     * adjust our ip_offset if the new payload size is different from what
+     * it used to be.
+     */
     if (ptag_hold && p->prev)
     {
         p_temp = p->prev;
@@ -136,9 +144,13 @@ u_int8_t *payload, u_int32_t payload_s, libnet_t *l, libnet_ptag_t ptag)
 
         if (p_temp->type == LIBNET_PBLOCK_IPDATA)
         {
+            int offset = payload_s;
+
             ptag_data = p_temp->ptag;
             offset -=  p_temp->b_len;
-            p->h_len += offset;
+            //p->h_len += offset;
+            // WRONG h_len is unused for checksum for IPv4, and even if it was used,
+            // the h_len doesn't depend on the payload size.
         }
         else
         {
@@ -157,6 +169,16 @@ u_int8_t *payload, u_int32_t payload_s, libnet_t *l, libnet_ptag_t ptag)
     if (payload && payload_s)
     {
         /* update ptag_data with the new payload */
+        // on create:
+        //    b_len = payload_s
+        //    l->total_size += b_len
+        //    h_len = 0
+        // on update:
+        //    b_len = payload_s
+        //    h_len += <diff in size between new b_len and old b_len>
+        //      increments if if b_len goes up, down if it goes down
+        // in either case:
+        //    copied = 0
         p_data = libnet_pblock_probe(l, ptag_data, payload_s,
                 LIBNET_PBLOCK_IPDATA);
         if (p_data == NULL)
@@ -171,6 +193,7 @@ u_int8_t *payload, u_int32_t payload_s, libnet_t *l, libnet_ptag_t ptag)
 
         if (ptag_data == LIBNET_PTAG_INITIALIZER)
         {
+            // IPDATA's h_len gets set to payload_s in both branches
             if (p_data->prev->type == LIBNET_PBLOCK_IPV4_H)
             {
                 libnet_pblock_update(l, p_data, payload_s,
@@ -180,6 +203,10 @@ u_int8_t *payload, u_int32_t payload_s, libnet_t *l, libnet_ptag_t ptag)
             }
             else
             {
+                // SR - I'm not sure how to reach this code. Maybe if the first
+                // time we added an ipv4 block, there was no payload, but when
+                // we modify the block the next time, we have payload?
+
                 /* update without setting this as the final pblock */
                 p_data->type  =  LIBNET_PBLOCK_IPDATA;
                 p_data->ptag  =  ++(l->ptag_state);
@@ -187,6 +214,7 @@ u_int8_t *payload, u_int32_t payload_s, libnet_t *l, libnet_ptag_t ptag)
 
                 /* Adjust h_len for checksum. */
                 p->h_len += payload_s;
+                // WRONG - IPV4 checksum doesn't include the payload_s.
 
                 /* data was added after the initial construction */
                 for (p_temp = l->protocol_blocks;
@@ -238,7 +266,16 @@ u_int8_t *payload, u_int32_t payload_s, libnet_t *l, libnet_ptag_t ptag)
      * FREDRAYNAL: as we insert a new IP header, all checksums for headers
      * placed after this one will refer to here.
      */
-    libnet_pblock_record_ip_offset(l, l->total_size);
+    // WRONG - the total_size when updating the pblock will include the link layer
+    // WRONG - it isn't called after adding options, so will be wrong by the amount of ip options
+    // WRONG - it updates the wrong protocol blocks:
+    //   - the first time it runs we set the ip offsets for p (ipv4), and
+    //     ipdata to the total size of just the ip portion
+    //   - the next time, it starts at end, which is the ethernet block, and
+    //     updates everything up to but not including the ipv4 block to the total size, which means it
+    //     changes just the ethernet block, and the offset it sets is the total size including the ethernet
+    //     header.... WTF?
+    libnet_pblock_record_ip_offset(l, p);
 
     return (ptag);
 bad:
@@ -323,7 +360,7 @@ libnet_autobuild_ipv4(u_int16_t len, u_int8_t prot, u_int32_t dst, libnet_t *l)
      * FREDRAYNAL: as we insert a new IP header, all checksums for headers
      * placed after this one will refer to here.
      */
-    libnet_pblock_record_ip_offset(l, l->total_size);
+    libnet_pblock_record_ip_offset(l, p);
     return (ptag);
 
 bad:
@@ -520,8 +557,13 @@ u_int8_t *payload, u_int32_t payload_s, libnet_t *l, libnet_ptag_t ptag)
     }
 
     /* no checksum for IPv6 */
-    return (ptag ? ptag : libnet_pblock_update(l, p, LIBNET_IPV6_H,
-            LIBNET_PBLOCK_IPV6_H));
+    ptag = ptag ? ptag : libnet_pblock_update(l, p, LIBNET_IPV6_H,
+            LIBNET_PBLOCK_IPV6_H);
+
+    libnet_pblock_record_ip_offset(l, p);
+
+    return ptag;
+
 bad:
     libnet_pblock_delete(l, p);
     return (-1);
diff --git a/libnet/src/libnet_init.c b/libnet/src/libnet_init.c
index 976b44c..58f4df1 100644
--- a/libnet/src/libnet_init.c
+++ b/libnet/src/libnet_init.c
@@ -250,6 +250,7 @@ libnet_getpbuf_size(libnet_t *l, libnet_ptag_t ptag)
 u_int32_t
 libnet_getpacket_size(libnet_t *l)
 {
+    // Why doesn't this return l->total_size?
     libnet_pblock_t *p;
     u_int32_t n;
 
diff --git a/libnet/src/libnet_pblock.c b/libnet/src/libnet_pblock.c
index 5e35aa5..5530c02 100644
--- a/libnet/src/libnet_pblock.c
+++ b/libnet/src/libnet_pblock.c
@@ -38,6 +38,7 @@
 #else
 #include "../include/win32/libnet.h"
 #endif
+#include <assert.h>
 
 libnet_pblock_t *
 libnet_pblock_probe(libnet_t *l, libnet_ptag_t ptag, u_int32_t n, u_int8_t type)
@@ -500,15 +501,18 @@ libnet_pblock_p2p(u_int8_t type)
 }
 
 void
-libnet_pblock_record_ip_offset(libnet_t *l, u_int32_t offset)
+libnet_pblock_record_ip_offset(libnet_t *l, libnet_pblock_t *p)
 {
-    libnet_pblock_t *p = l->pblock_end;
+    libnet_pblock_t *c;
+    u_int32_t ip_offset = 0;
 
-    do
-    {
-        p->ip_offset = offset;
-        p = p->prev;
-    } while (p && p->type != LIBNET_PBLOCK_IPV4_H);
+    assert(p->type == LIBNET_PBLOCK_IPV4_H || p->type == LIBNET_PBLOCK_IPV6_H);
+
+    for(c = p; c; c = c->prev)
+        ip_offset += c->b_len;
+
+    for(c = p; c; c = c->prev)
+        c->ip_offset = ip_offset;
 }
 
 
diff --git a/unmerged/bug-418975.patch b/unmerged/bug-418975.patch
deleted file mode 100644
index 7376070..0000000
--- a/unmerged/bug-418975.patch
+++ /dev/null
@@ -1,243 +0,0 @@
-Index: src/libnet_init.c
-===================================================================
---- src/libnet_init.c	(revision 374)
-+++ src/libnet_init.c	(working copy)
-@@ -250,6 +250,7 @@
- u_int32_t
- libnet_getpacket_size(libnet_t *l)
- {
-+    // Why doesn't this return l->total_size?
-     libnet_pblock_t *p;
-     u_int32_t n;
- 
-Index: src/libnet_build_ip.c
-===================================================================
---- src/libnet_build_ip.c	(revision 374)
-+++ src/libnet_build_ip.c	(working copy)
-@@ -45,7 +45,6 @@
- u_int8_t ttl, u_int8_t prot, u_int16_t sum, u_int32_t src, u_int32_t dst,
- u_int8_t *payload, u_int32_t payload_s, libnet_t *l, libnet_ptag_t ptag)
- {
--    int offset;
-     u_int32_t h, n, i, j;
-     libnet_pblock_t *p, *p_data, *p_temp;
-     struct libnet_ipv4_hdr ip_hdr;
-@@ -58,9 +57,12 @@
- 
-     n = LIBNET_IPV4_H;                      /* size of memory block */
-     h = len;                                /* header length */
-+    // WRONG - this is total len of ip packet, and is put into the IP header
-     ptag_data = 0;                          /* used if options are present */
-+    // WRONG - is used if there is ipv4 payload
- 
-     if (h + payload_s > IP_MAXPACKET)
-+    // WRONG - h is the total length, it already includes payload_s
-     {
-          snprintf(l->err_buf, LIBNET_ERRBUF_SIZE,
-                 "%s(): IP packet too large\n", __func__);
-@@ -97,6 +99,9 @@
-             ip_hdr.ip_hl += j;
-         }
-     }
-+    // Note that p->h_len is not adjusted. This seems a bug, but it is because
-+    // it is not used!  libnet_do_checksum() is passed the h_len (as `len'),
-+    // but for IPPROTO_IP it is ignored in favor of the ip_hl.
- 
-     ip_hdr.ip_tos        = tos;                       /* IP tos */
-     ip_hdr.ip_len        = htons(h);                  /* total length */
-@@ -123,7 +128,10 @@
-     }
- 
-     /* find and set the appropriate ptag, or else use the default of 0 */
--    offset = payload_s;
-+    /* When updating the ipv4 block, we need to find the data block, and
-+     * adjust our ip_offset if the new payload size is different from what
-+     * it used to be.
-+     */
-     if (ptag_hold && p->prev)
-     {
-         p_temp = p->prev;
-@@ -136,9 +144,13 @@
- 
-         if (p_temp->type == LIBNET_PBLOCK_IPDATA)
-         {
-+            int offset = payload_s;
-+
-             ptag_data = p_temp->ptag;
-             offset -=  p_temp->b_len;
--            p->h_len += offset;
-+            //p->h_len += offset;
-+            // WRONG h_len is unused for checksum for IPv4, and even if it was used,
-+            // the h_len doesn't depend on the payload size.
-         }
-         else
-         {
-@@ -157,6 +169,16 @@
-     if (payload && payload_s)
-     {
-         /* update ptag_data with the new payload */
-+        // on create:
-+        //    b_len = payload_s
-+        //    l->total_size += b_len
-+        //    h_len = 0
-+        // on update:
-+        //    b_len = payload_s
-+        //    h_len += <diff in size between new b_len and old b_len>
-+        //      increments if if b_len goes up, down if it goes down
-+        // in either case:
-+        //    copied = 0
-         p_data = libnet_pblock_probe(l, ptag_data, payload_s,
-                 LIBNET_PBLOCK_IPDATA);
-         if (p_data == NULL)
-@@ -171,6 +193,7 @@
- 
-         if (ptag_data == LIBNET_PTAG_INITIALIZER)
-         {
-+            // IPDATA's h_len gets set to payload_s in both branches
-             if (p_data->prev->type == LIBNET_PBLOCK_IPV4_H)
-             {
-                 libnet_pblock_update(l, p_data, payload_s,
-@@ -180,6 +203,10 @@
-             }
-             else
-             {
-+                // SR - I'm not sure how to reach this code. Maybe if the first
-+                // time we added an ipv4 block, there was no payload, but when
-+                // we modify the block the next time, we have payload?
-+
-                 /* update without setting this as the final pblock */
-                 p_data->type  =  LIBNET_PBLOCK_IPDATA;
-                 p_data->ptag  =  ++(l->ptag_state);
-@@ -187,6 +214,7 @@
- 
-                 /* Adjust h_len for checksum. */
-                 p->h_len += payload_s;
-+                // WRONG - IPV4 checksum doesn't include the payload_s.
- 
-                 /* data was added after the initial construction */
-                 for (p_temp = l->protocol_blocks;
-@@ -238,7 +266,16 @@
-      * FREDRAYNAL: as we insert a new IP header, all checksums for headers
-      * placed after this one will refer to here.
-      */
--    libnet_pblock_record_ip_offset(l, l->total_size);
-+    // WRONG - the total_size when updating the pblock will include the link layer
-+    // WRONG - it isn't called after adding options, so will be wrong by the amount of ip options
-+    // WRONG - it updates the wrong protocol blocks:
-+    //   - the first time it runs we set the ip offsets for p (ipv4), and
-+    //     ipdata to the total size of just the ip portion
-+    //   - the next time, it starts at end, which is the ethernet block, and
-+    //     updates everything up to but not including the ipv4 block to the total size, which means it
-+    //     changes just the ethernet block, and the offset it sets is the total size including the ethernet
-+    //     header.... WTF?
-+    libnet_pblock_record_ip_offset(l, p);
- 
-     return (ptag);
- bad:
-@@ -323,7 +360,7 @@
-      * FREDRAYNAL: as we insert a new IP header, all checksums for headers
-      * placed after this one will refer to here.
-      */
--    libnet_pblock_record_ip_offset(l, l->total_size);
-+    libnet_pblock_record_ip_offset(l, p);
-     return (ptag);
- 
- bad:
-@@ -407,7 +444,7 @@
-     }
- 
-     /* append padding */
--    n = libnet_pblock_append(l, p, "\0\0\0", adj_size - options_s);
-+    n = libnet_pblock_append(l, p, (u_int8_t*) "\0\0\0", adj_size - options_s);
-     if (n == -1)
-     {
-         goto bad;
-Index: src/libnet_pblock.c
-===================================================================
---- src/libnet_pblock.c	(revision 374)
-+++ src/libnet_pblock.c	(working copy)
-@@ -38,6 +38,7 @@
- #else
- #include "../include/win32/libnet.h"
- #endif
-+#include <assert.h>
- 
- libnet_pblock_t *
- libnet_pblock_probe(libnet_t *l, libnet_ptag_t ptag, u_int32_t n, u_int8_t type)
-@@ -496,15 +497,18 @@
- }
- 
- void
--libnet_pblock_record_ip_offset(libnet_t *l, u_int32_t offset)
-+libnet_pblock_record_ip_offset(libnet_t *l, libnet_pblock_t *p)
- {
--    libnet_pblock_t *p = l->pblock_end;
-+    libnet_pblock_t *c;
-+    u_int32_t ip_offset = 0;
- 
--    do
--    {
--        p->ip_offset = offset;
--        p = p->prev;
--    } while (p && p->type != LIBNET_PBLOCK_IPV4_H);
-+    assert(p->type == LIBNET_PBLOCK_IPV4_H);
-+
-+    for(c = p; c; c = c->prev)
-+        ip_offset += c->b_len;
-+
-+    for(c = p; c; c = c->prev)
-+        c->ip_offset = ip_offset;
- }
- 
- 
-Index: include/libnet/libnet-structures.h
-===================================================================
---- include/libnet/libnet-structures.h	(revision 374)
-+++ include/libnet/libnet-structures.h	(working copy)
-@@ -79,8 +79,19 @@
-     u_int8_t *buf;                      /* protocol buffer */
-     u_int32_t b_len;                    /* length of buf */
-     u_int16_t h_len;                    /* header length (for checksumming) */
--    u_int32_t ip_offset;                /* offset to IP header for csums */
--    u_int32_t copied;                   /* bytes copied */
-+       /* Unused for IPV4_H block types.
-+        * For protocols that sit on top of IP, it should be the the amount of
-+        * buf that is the header, and will be included in the checksum.
-+        */
-+    u_int32_t ip_offset;                /* offset from end of pkt to beginning of IP header for csums */
-+       /* Unused for IPV4_H block types.
-+        * For protocols that sit on top of IP (UDP, ICMP, ...), they often
-+        * include some information from the IP header (in the form of a "pseudo
-+        * header") in their own checksum calculation. To build that
-+        * pseudo-header, thet need to find the real header.
-+        */
-+    u_int32_t copied;                   /* bytes copied - the amount of data copied into buf */
-+       /* Used and updated by libnet_pblock_append(). */
-     u_int8_t type;                      /* type of pblock */
- /* this needs to be updated every time a new packet builder is added */
- #define LIBNET_PBLOCK_ARP_H             0x01    /* ARP header */
-Index: include/libnet/libnet-functions.h
-===================================================================
---- include/libnet/libnet-functions.h	(revision 374)
-+++ include/libnet/libnet-functions.h	(working copy)
-@@ -794,6 +794,7 @@
- /**
-  * Builds a version 4 RFC 791 Internet Protocol (IP) header.
-  * @param len total length of the IP packet including all subsequent data
-+ *   FIXME There is no reason this can't be calculated if zero is passed.
-  * @param tos type of service bits
-  * @param id IP identification number
-  * @param frag fragmentation bits and offset
-@@ -2074,10 +2075,10 @@
-   * Function updates referer used to compute the checksum. All
-   * pblock need to know where is their referer (ie IP header).
-   * So, this function is called each time a new IP header is inserted.
--  * It updates the ip_pos field (referer) of each subsequent pblock.
-+  * It updates the ip_offset field (referer) of each previous pblock.
-   */
- void
--libnet_pblock_record_ip_offset(libnet_t *l, u_int32_t offset);
-+libnet_pblock_record_ip_offset(libnet_t *l, libnet_pblock_t *p);
- 
- /*
-  * [Internal] 
diff --git a/unmerged/ipv6_icmpv4.patch b/unmerged/ipv6_icmpv4.patch
deleted file mode 100644
index 5b98685..0000000
--- a/unmerged/ipv6_icmpv4.patch
+++ /dev/null
@@ -1,32 +0,0 @@
-Index: src/libnet_build_ip.c
-===================================================================
---- src/libnet_build_ip.c	(revision 382)
-+++ src/libnet_build_ip.c	(working copy)
-@@ -557,8 +557,12 @@
-     }
- 
-     /* no checksum for IPv6 */
--    return (ptag ? ptag : libnet_pblock_update(l, p, LIBNET_IPV6_H,
--            LIBNET_PBLOCK_IPV6_H));
-+    ptag = ptag ? ptag : libnet_pblock_update(l, p, LIBNET_IPV6_H,
-+            LIBNET_PBLOCK_IPV6_H);
-+
-+    libnet_pblock_record_ip_offset(l, p);
-+
-+    return ptag;
- bad:
-     libnet_pblock_delete(l, p);
-     return (-1);
-Index: src/libnet_pblock.c
-===================================================================
---- src/libnet_pblock.c	(revision 382)
-+++ src/libnet_pblock.c	(working copy)
-@@ -502,7 +509,7 @@
-     libnet_pblock_t *c;
-     u_int32_t ip_offset = 0;
- 
--    assert(p->type == LIBNET_PBLOCK_IPV4_H);
-+    assert(p->type == LIBNET_PBLOCK_IPV4_H || p->type == LIBNET_PBLOCK_IPV6_H);
- 
-     for(c = p; c; c = c->prev)
-         ip_offset += c->b_len;