DO NOT MERGE: Modify the pseudo-header checksum functions.

- Remove the initial checksum, which we don't use anywhere.
- Add the upper-layer protocol to the IPv6 function. Currently
  this is always the same as the next header field in the IPv6
  header, but technically it's the upper-layer header after all
  the extension headers. This is required to support fragments.

Bug: 11542311
Change-Id: Ie1a20fa74ee5bc933c1014bab74ae2957979b2b8

5 files changed, 18 insertions, 18 deletions

diff --git a/checksum.c b/checksum.c
index 099be6a..3dd1e00 100644
--- a/checksum.c
+++ b/checksum.c
@@ -84,16 +84,16 @@ uint16_t ip_checksum(const void *data, int len) {
 
 /* function: ipv6_pseudo_header_checksum
  * calculate the pseudo header checksum for use in tcp/udp/icmp headers
- * current - the current checksum or 0 to start a new checksum
- * ip6     - the ipv6 header
- * len     - the transport length (transport header + payload)
+ * ip6      - the ipv6 header
+ * len      - the transport length (transport header + payload)
+ * protocol - the transport layer protocol, can be different from ip6->ip6_nxt for fragments
  */
-uint32_t ipv6_pseudo_header_checksum(uint32_t current, const struct ip6_hdr *ip6, uint16_t len) {
+uint32_t ipv6_pseudo_header_checksum(const struct ip6_hdr *ip6, uint16_t len, uint8_t protocol) {
   uint32_t checksum_len, checksum_next;
-
   checksum_len = htonl((uint32_t) len);
-  checksum_next = htonl(ip6->ip6_nxt);
+  checksum_next = htonl(protocol);
 
+  uint32_t current = 0;
   current = ip_checksum_add(current, &(ip6->ip6_src), sizeof(struct in6_addr));
   current = ip_checksum_add(current, &(ip6->ip6_dst), sizeof(struct in6_addr));
   current = ip_checksum_add(current, &checksum_len, sizeof(checksum_len));
@@ -104,16 +104,16 @@ uint32_t ipv6_pseudo_header_checksum(uint32_t current, const struct ip6_hdr *ip6
 
 /* function: ipv4_pseudo_header_checksum
  * calculate the pseudo header checksum for use in tcp/udp headers
- * current - the current checksum or 0 to start a new checksum
  * ip      - the ipv4 header
  * len     - the transport length (transport header + payload)
  */
-uint32_t ipv4_pseudo_header_checksum(uint32_t current, const struct iphdr *ip, uint16_t len) {
+uint32_t ipv4_pseudo_header_checksum(const struct iphdr *ip, uint16_t len) {
   uint16_t temp_protocol, temp_length;
 
   temp_protocol = htons(ip->protocol);
   temp_length = htons(len);
 
+  uint32_t current = 0;
   current = ip_checksum_add(current, &(ip->saddr), sizeof(uint32_t));
   current = ip_checksum_add(current, &(ip->daddr), sizeof(uint32_t));
   current = ip_checksum_add(current, &temp_protocol, sizeof(uint16_t));
diff --git a/checksum.h b/checksum.h
index 44921f0..6195810 100644
--- a/checksum.h
+++ b/checksum.h
@@ -22,8 +22,8 @@ uint32_t ip_checksum_add(uint32_t current, const void *data, int len);
 uint16_t ip_checksum_finish(uint32_t temp_sum);
 uint16_t ip_checksum(const void *data, int len);
 
-uint32_t ipv6_pseudo_header_checksum(uint32_t current, const struct ip6_hdr *ip6, uint16_t len);
-uint32_t ipv4_pseudo_header_checksum(uint32_t current, const struct iphdr *ip, uint16_t len);
+uint32_t ipv6_pseudo_header_checksum(const struct ip6_hdr *ip6, uint16_t len, uint8_t protocol);
+uint32_t ipv4_pseudo_header_checksum(const struct iphdr *ip, uint16_t len);
 
 uint16_t ip_checksum_adjust(uint16_t checksum, uint32_t old_hdr_sum, uint32_t new_hdr_sum);
 
diff --git a/dump.c b/dump.c
index 8567655..94e4796 100644
--- a/dump.c
+++ b/dump.c
@@ -147,14 +147,14 @@ void dump_udp_generic(const struct udphdr *udp, uint32_t temp_checksum, const ch
 /* print ipv4/udp header */
 void dump_udp(const struct udphdr *udp, const struct iphdr *ip, const char *payload, size_t payload_size) {
   uint32_t temp_checksum;
-  temp_checksum = ipv4_pseudo_header_checksum(0, ip, sizeof(*udp) + payload_size);
+  temp_checksum = ipv4_pseudo_header_checksum(ip, sizeof(*udp) + payload_size);
   dump_udp_generic(udp, temp_checksum, payload, payload_size);
 }
 
 /* print ipv6/udp header */
 void dump_udp6(const struct udphdr *udp, const struct ip6_hdr *ip6, const char *payload, size_t payload_size) {
   uint32_t temp_checksum;
-  temp_checksum = ipv6_pseudo_header_checksum(0, ip6, sizeof(*udp) + payload_size);
+  temp_checksum = ipv6_pseudo_header_checksum(ip6, sizeof(*udp) + payload_size, IPPROTO_UDP);
   dump_udp_generic(udp, temp_checksum, payload, payload_size);
 }
 
@@ -203,7 +203,7 @@ void dump_tcp_generic(const struct tcphdr *tcp, const char *options, size_t opti
 void dump_tcp(const struct tcphdr *tcp, const struct iphdr *ip, const char *payload, size_t payload_size, const char *options, size_t options_size) {
   uint32_t temp_checksum;
 
-  temp_checksum = ipv4_pseudo_header_checksum(0, ip, sizeof(*tcp) + options_size + payload_size);
+  temp_checksum = ipv4_pseudo_header_checksum(ip, sizeof(*tcp) + options_size + payload_size);
   dump_tcp_generic(tcp, options, options_size, temp_checksum, payload, payload_size);
 }
 
@@ -211,7 +211,7 @@ void dump_tcp(const struct tcphdr *tcp, const struct iphdr *ip, const char *payl
 void dump_tcp6(const struct tcphdr *tcp, const struct ip6_hdr *ip6, const char *payload, size_t payload_size, const char *options, size_t options_size) {
   uint32_t temp_checksum;
 
-  temp_checksum = ipv6_pseudo_header_checksum(0, ip6, sizeof(*tcp) + options_size + payload_size);
+  temp_checksum = ipv6_pseudo_header_checksum(ip6, sizeof(*tcp) + options_size + payload_size, IPPROTO_TCP);
   dump_tcp_generic(tcp, options, options_size, temp_checksum, payload, payload_size);
 }
 
diff --git a/ipv4.c b/ipv4.c
index c828ffa..e2636b4 100644
--- a/ipv4.c
+++ b/ipv4.c
@@ -112,8 +112,8 @@ int ipv4_packet(clat_packet out, int pos, const char *packet, size_t len) {
   out[pos].iov_len = sizeof(struct ip6_hdr);
 
   // Calculate the pseudo-header checksum.
-  old_sum = ipv4_pseudo_header_checksum(0, header, len_left);
-  new_sum = ipv6_pseudo_header_checksum(0, ip6_targ, len_left);
+  old_sum = ipv4_pseudo_header_checksum(header, len_left);
+  new_sum = ipv6_pseudo_header_checksum(ip6_targ, len_left, nxthdr);
 
   if (nxthdr == IPPROTO_ICMPV6) {
     iov_len = icmp_packet(out, pos + 1, (const struct icmphdr *) next_header, new_sum, len_left);
diff --git a/ipv6.c b/ipv6.c
index 371d9e1..d188e47 100644
--- a/ipv6.c
+++ b/ipv6.c
@@ -125,8 +125,8 @@ int ipv6_packet(clat_packet out, int pos, const char *packet, size_t len) {
   out[pos].iov_len = sizeof(struct iphdr);
 
   // Calculate the pseudo-header checksum.
-  old_sum = ipv6_pseudo_header_checksum(0, ip6, len_left);
-  new_sum = ipv4_pseudo_header_checksum(0, ip_targ, len_left);
+  old_sum = ipv6_pseudo_header_checksum(ip6, len_left, protocol);
+  new_sum = ipv4_pseudo_header_checksum(ip_targ, len_left);
 
   // does not support IPv6 extension headers, this will drop any packet with them
   if (protocol == IPPROTO_ICMP) {