diff options
Diffstat (limited to 'tcp.c')
| -rw-r--r-- | tcp.c | 66 |
1 files changed, 65 insertions, 1 deletions
@@ -399,7 +399,7 @@ static int tcp_sock_ns [NUM_PORTS][IP_VERSIONS]; */ static union inany_addr low_rtt_dst[LOW_RTT_TABLE_SIZE]; -char tcp_buf_discard [MAX_WINDOW]; +char tcp_buf_discard [BUF_DISCARD_SIZE]; /* Does the kernel support TCP_PEEK_OFF? */ bool peek_offset_cap; @@ -3844,3 +3844,67 @@ fail: return 0; } + +/** + * tcp_prepare_iov() - Prepare iov according to kernel capability + * @msg: Message header to update + * @iov: iovec to receive TCP payload and data to discard + * @already_sent: Bytes sent after the last acknowledged one + * @payload_iov_cnt: Number of TCP payload iovec entries + * + * Return: 0 on success, -1 if already_sent cannot be discarded fully + */ +int tcp_prepare_iov(struct msghdr *msg, struct iovec *iov, + uint32_t already_sent, int payload_iov_cnt) +{ + /* + * IOV layout + * |- tcp_buf_discard -|---------- TCP data slots ------------| + * + * with discarded data: + * |------ddddddddddddd|ttttttttttttt-------------------------| + * ^ + * | + * msg_iov + * + * without discarded data: + * |-------------------|ttttttttttttt-------------------------| + * ^ + * | + * msg_iov + * d: discard data + * t: TCP data + */ + if (peek_offset_cap) { + msg->msg_iov = iov + DISCARD_IOV_NUM; + msg->msg_iovlen = payload_iov_cnt; + } else { + int discard_cnt, discard_iov_rem; + struct iovec *iov_start; + int i; + + discard_cnt = DIV_ROUND_UP(already_sent, BUF_DISCARD_SIZE); + if (discard_cnt > DISCARD_IOV_NUM) { + debug("Failed to discard %u already sent bytes", + already_sent); + return -1; + } + + discard_iov_rem = already_sent % BUF_DISCARD_SIZE; + + iov_start = iov + (DISCARD_IOV_NUM - discard_cnt); + + /* Multiple iov entries pointing to the same buffer */ + for (i = 0; i < discard_cnt; i++) { + iov_start[i].iov_base = tcp_buf_discard; + iov_start[i].iov_len = BUF_DISCARD_SIZE; + } + if (discard_iov_rem) + iov[DISCARD_IOV_NUM - 1].iov_len = discard_iov_rem; + + msg->msg_iov = iov_start; + msg->msg_iovlen = discard_cnt + payload_iov_cnt; + } + + return 0; +} |