diff options
| -rw-r--r-- | tcp.c | 42 |
1 files changed, 39 insertions, 3 deletions
@@ -1653,6 +1653,23 @@ static int tcp_data_from_sock(const struct ctx *c, struct tcp_tap_conn *conn) } /** + * tcp_packet_data_len() - Get data (TCP payload) length for a TCP packet + * @th: Pointer to TCP header + * @l4len: TCP packet length, including TCP header + * + * Return: data length of TCP packet, -1 on invalid value of Data Offset field + */ +static ssize_t tcp_packet_data_len(const struct tcphdr *th, size_t l4len) +{ + size_t off = th->doff * 4UL; + + if (off < sizeof(*th) || off > l4len) + return -1; + + return l4len - off; +} + +/** * tcp_data_from_tap() - tap/guest data for established connection * @c: Execution context * @conn: Connection pointer @@ -2113,9 +2130,28 @@ int tcp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af, /* Established connections not accepting data from tap */ if (conn->events & TAP_FIN_RCVD) { - tcp_sock_consume(conn, ntohl(th->ack_seq)); - tcp_update_seqack_from_tap(c, conn, ntohl(th->ack_seq)); - if (tcp_tap_window_update(c, conn, ntohs(th->window))) + bool retr; + + retr = th->ack && !tcp_packet_data_len(th, l4len) && !th->fin && + ntohl(th->ack_seq) == conn->seq_ack_from_tap && + ntohs(th->window) == conn->wnd_from_tap; + + /* On socket flush failure, pretend there was no ACK, try again + * later + */ + if (th->ack && !tcp_sock_consume(conn, ntohl(th->ack_seq))) + tcp_update_seqack_from_tap(c, conn, ntohl(th->ack_seq)); + + if (retr) { + flow_trace(conn, + "fast re-transmit, ACK: %u, previous sequence: %u", + ntohl(th->ack_seq), conn->seq_to_tap); + + if (tcp_rewind_seq(c, conn)) + return -1; + } + + if (tcp_tap_window_update(c, conn, ntohs(th->window)) || retr) tcp_data_from_sock(c, conn); if (conn->seq_ack_from_tap == conn->seq_to_tap) { |