diff options
Diffstat (limited to 'lib/src')
| -rw-r--r-- | lib/src/protocol/tcp.c | 34 |
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 |