aboutsummaryrefslogtreecommitdiffstats
path: root/lib/src
diff options
context:
space:
mode:
Diffstat (limited to 'lib/src')
-rw-r--r--lib/src/protocol/tcp.c34
1 files changed, 27 insertions, 7 deletions
diff --git a/lib/src/protocol/tcp.c b/lib/src/protocol/tcp.c
index 31c495ff4..7b7c44ef7 100644
--- a/lib/src/protocol/tcp.c
+++ b/lib/src/protocol/tcp.c
@@ -48,15 +48,20 @@ DECLARE_set_payload_length (tcp, UNEXPECTED);
int
tcp_init_packet_header (hicn_type_t type, hicn_protocol_t * h)
{
- h->tcp = (_tcp_header_t)
- {
- .sport = htons (TCP_DEFAULT_SRC_PORT),.dport =
- htons (TCP_DEFAULT_DST_PORT),.seq = 0,.seq_ack =
- 0,.data_offset_and_reserved = TCP_DEFAULT_DATA_OFFSET_RES,.flags =
+ h->tcp = (_tcp_header_t) {
+ .sport = htons (TCP_DEFAULT_SRC_PORT),
+ .dport = htons (TCP_DEFAULT_DST_PORT),
+ .seq = 0,
+ .seq_ack = 0,
+ .data_offset_and_reserved = TCP_DEFAULT_DATA_OFFSET_RES,
+ .flags =
TCP_DEFAULT_CWR << 7 | TCP_DEFAULT_ECE << 6 | TCP_DEFAULT_URG << 5 |
TCP_DEFAULT_ACK << 4 | TCP_DEFAULT_PSH << 3 | TCP_DEFAULT_RST << 2 |
- TCP_DEFAULT_SYN << 1 | TCP_DEFAULT_FIN << 0,.window =
- htons (TCP_DEFAULT_WINDOW_SIZE),.csum = 0,.urg_ptr = 65000,};
+ TCP_DEFAULT_SYN << 1 | TCP_DEFAULT_FIN << 0,
+ .window = htons (TCP_DEFAULT_WINDOW_SIZE),
+ .csum = 0xffff,
+ .urg_ptr = 65000,
+ };
uint8_t ah_flag = type.l2 == IPPROTO_AH ? AH_FLAG : 0;
@@ -253,6 +258,21 @@ tcp_rewrite_interest (hicn_type_t type, hicn_protocol_t * h,
{
u16 *tcp_checksum = &(h->tcp.csum);
+ /* As per RFC1624
+ * In one's complement, there are two representations of zero: the all
+ * zero and the all one bit values, often referred to as +0 and -0.
+ * One's complement addition of non-zero inputs can produce -0 as a
+ * result, but never +0. Since there is guaranteed to be at least one
+ * non-zero field in the IP header, and the checksum field in the
+ * protocol header is the complement of the sum, the checksum field can
+ * never contain ~(+0), which is -0 (0xFFFF). It can, however, contain
+ * ~(-0), which is +0 (0x0000).
+ */
+ if (*tcp_checksum == 0xffff) {
+ /* Invalid checksum, no need to compute incremental update */
+ return HICN_LIB_ERROR_REWRITE_CKSUM_REQUIRED;
+ }
+
/*
* Padding fields are set to zero so we can apply checksum on the
* whole struct by interpreting it as IPv6 in all cases