Pass in the length to pseudo checksum functions
Currently, the pseudo-header checksum calculation functions get
the transport layer length from the IP header. This requires that
the length be known at IP header construction time, which
does not allow transport layer translation functions to change
the length of the packet later. Have the transport functions
pass in the size directly.
Bug: 8276725
Change-Id: I76a93f5e66181bec21d68f779c68c54090a77c33
diff --git a/checksum.c b/checksum.c
index 14b7113..a4dc9b8 100644
--- a/checksum.c
+++ b/checksum.c
@@ -28,12 +28,12 @@
/* function: ip_checksum_add
* adds data to a checksum
- * current_sum - the current checksum (or 0 to start a new checksum)
+ * current - the current checksum (or 0 to start a new checksum)
* data - the data to add to the checksum
* len - length of data
*/
-uint32_t ip_checksum_add(uint32_t current_sum, const void *data, int len) {
- uint32_t checksum = current_sum;
+uint32_t ip_checksum_add(uint32_t current, const void *data, int len) {
+ uint32_t checksum = current;
int left = len;
const uint16_t *data_16 = data;
@@ -76,38 +76,40 @@
/* function: ipv6_pseudo_header_checksum
* calculate the pseudo header checksum for use in tcp/udp/icmp headers
- * current_sum - the current checksum or 0 to start a new checksum
- * ip6 - the ipv6 header
+ * current - the current checksum or 0 to start a new checksum
+ * ip6 - the ipv6 header
+ * len - the transport length (transport header + payload)
*/
-uint32_t ipv6_pseudo_header_checksum(uint32_t current_sum, const struct ip6_hdr *ip6) {
+uint32_t ipv6_pseudo_header_checksum(uint32_t current, const struct ip6_hdr *ip6, uint16_t len) {
uint32_t checksum_len, checksum_next;
- checksum_len = htonl(ntohs(ip6->ip6_plen));
+ checksum_len = htonl((uint32_t) len);
checksum_next = htonl(ip6->ip6_nxt);
- current_sum = ip_checksum_add(current_sum,&(ip6->ip6_src),sizeof(struct in6_addr));
- current_sum = ip_checksum_add(current_sum,&(ip6->ip6_dst),sizeof(struct in6_addr));
- current_sum = ip_checksum_add(current_sum,&checksum_len,sizeof(checksum_len));
- current_sum = ip_checksum_add(current_sum,&checksum_next,sizeof(checksum_next));
+ 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));
+ current = ip_checksum_add(current, &checksum_next, sizeof(checksum_next));
- return current_sum;
+ return current;
}
/* function: ipv4_pseudo_header_checksum
* calculate the pseudo header checksum for use in tcp/udp headers
- * current_sum - the current checksum or 0 to start a new checksum
- * ip - the ipv4 header
+ * 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_sum, const struct iphdr *ip) {
+uint32_t ipv4_pseudo_header_checksum(uint32_t current, const struct iphdr *ip, uint16_t len) {
uint16_t temp_protocol, temp_length;
temp_protocol = htons(ip->protocol);
- temp_length = htons(ntohs(ip->tot_len) - ip->ihl*4);
+ temp_length = htons(len);
- current_sum = ip_checksum_add(current_sum, &(ip->saddr), sizeof(uint32_t));
- current_sum = ip_checksum_add(current_sum, &(ip->daddr), sizeof(uint32_t));
- current_sum = ip_checksum_add(current_sum, &temp_protocol, sizeof(uint16_t));
- current_sum = ip_checksum_add(current_sum, &temp_length, sizeof(uint16_t));
+ 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));
+ current = ip_checksum_add(current, &temp_length, sizeof(uint16_t));
- return current_sum;
+ return current;
}