From 539dcf5add9c8a3cd22ca8af89069be1bbbcf3f6 Mon Sep 17 00:00:00 2001 From: Stefano Brivio Date: Wed, 4 Aug 2021 01:35:45 +0200 Subject: tcp: Fast re-transmit, more fixes for closing states and no_snd_wnd ...and while at it, fix an issue in the calculation of the last IOV buffer size: if we can't receive enough data to fill up the window, the last buffer can be filled completely. Also streamline the code setting iovec lengths if cached values are not matching. Signed-off-by: Stefano Brivio --- tcp.c | 118 +++++++++++++++++++++++++++++++++++++++++------------------------- 1 file changed, 73 insertions(+), 45 deletions(-) diff --git a/tcp.c b/tcp.c index 5f9d5f6..977e745 100644 --- a/tcp.c +++ b/tcp.c @@ -1545,12 +1545,16 @@ static int tcp_data_from_sock(struct ctx *c, struct tcp_tap_conn *conn, already_sent = conn->seq_to_tap - conn->seq_ack_from_tap; if (!conn->tap_window || already_sent >= conn->tap_window) - return 1; + return 0; fill_bufs = DIV_ROUND_UP(conn->tap_window - already_sent, conn->mss_guest); - if (fill_bufs > TCP_TAP_FRAMES) + if (fill_bufs > TCP_TAP_FRAMES) { fill_bufs = TCP_TAP_FRAMES; + iov_rem = 0; + } else { + iov_rem = (conn->tap_window - already_sent) % conn->mss_guest; + } /* Adjust iovec length for recvmsg() based on what was set last time. */ if (v4) { @@ -1562,21 +1566,16 @@ static int tcp_data_from_sock(struct ctx *c, struct tcp_tap_conn *conn, buf_mss = &tcp6_l2_buf_mss; buf_mss_nr_set = &tcp6_l2_buf_mss_nr_set; } - if (*buf_mss != conn->mss_guest) { - for (i = 0; i < fill_bufs; i++) - iov[i].iov_len = conn->mss_guest; - *buf_mss = conn->mss_guest; - *buf_mss_nr_set = fill_bufs - 1; - } else if (*buf_mss_nr_set < fill_bufs) { - for (i = *buf_mss_nr_set; i < fill_bufs; i++) - iov[i].iov_len = conn->mss_guest; - *buf_mss_nr_set = fill_bufs - 1; - } + if (*buf_mss != conn->mss_guest) + *buf_mss_nr_set = 0; + for (i = *buf_mss_nr_set; i < fill_bufs; i++) + iov[i].iov_len = conn->mss_guest; + *buf_mss = conn->mss_guest; + *buf_mss_nr_set = fill_bufs - 1; /* First buffer is to discard data, last one may be partially filled. */ iov[-1].iov_len = already_sent; - iov_rem = (conn->tap_window - already_sent) % conn->mss_guest; - if (iov_rem && fill_bufs < TCP_TAP_FRAMES) + if (iov_rem) iov[fill_bufs - 1].iov_len = iov_rem; if (v4) tcp4_l2_mh_sock.msg_iovlen = fill_bufs + 1; @@ -1616,27 +1615,28 @@ static int tcp_data_from_sock(struct ctx *c, struct tcp_tap_conn *conn, buf_mss_tap = &tcp6_l2_buf_mss_tap; buf_mss_tap_nr_set = &tcp6_l2_buf_mss_tap_nr_set; } - if (*buf_mss_tap != mss_tap) { - for (i = 0; i < send_bufs; i++) - iov_tap[i].iov_len = mss_tap; - *buf_mss_tap = mss_tap; - *buf_mss_tap_nr_set = send_bufs; - } else if (*buf_mss_tap_nr_set < send_bufs) { - for (i = *buf_mss_tap_nr_set; i < send_bufs; i++) - iov_tap[i].iov_len = mss_tap; - *buf_mss_tap_nr_set = send_bufs; - } + if (*buf_mss_tap != mss_tap) + *buf_mss_tap_nr_set = 0; + for (i = *buf_mss_tap_nr_set; i < send_bufs; i++) + iov_tap[i].iov_len = mss_tap; + *buf_mss_tap = mss_tap; + *buf_mss_tap_nr_set = send_bufs; iov_tap[send_bufs - 1].iov_len = mss_tap - conn->mss_guest + last_len; /* Likely, some new data was acked too. */ if (conn->seq_from_tap != conn->seq_ack_to_tap) { - if (getsockopt(conn->sock, SOL_TCP, TCP_INFO, &info, &sl)) - goto err; + if (conn->no_snd_wnd) { + conn->seq_ack_to_tap = conn->seq_from_tap; + } else { + if (getsockopt(conn->sock, SOL_TCP, TCP_INFO, &info, + &sl)) + goto err; - conn->tcpi_acked_last = info.tcpi_bytes_acked; - conn->seq_ack_to_tap = info.tcpi_bytes_acked + - conn->seq_init_from_tap; + conn->tcpi_acked_last = info.tcpi_bytes_acked; + conn->seq_ack_to_tap = info.tcpi_bytes_acked + + conn->seq_init_from_tap; + } } else { info.tcpi_snd_wscale = conn->ws; info.tcpi_snd_wnd = conn->tcpi_snd_wnd; @@ -1776,11 +1776,14 @@ err: goto out_restore_iov; zero_len: - if (conn->state >= ESTABLISHED_SOCK_FIN) - goto out_restore_iov; + if (conn->state == FIN_WAIT_1) { + tcp_tap_state(conn, FIN_WAIT_1_SOCK_FIN); + } else if (conn->state < ESTABLISHED_SOCK_FIN) { + tcp_tap_state(conn, ESTABLISHED_SOCK_FIN); + shutdown(conn->sock, SHUT_RD); + tcp_send_to_tap(c, conn, FIN | ACK, NULL, 0); + } - tcp_tap_state(conn, ESTABLISHED_SOCK_FIN); - tcp_send_to_tap(c, conn, FIN | ACK, NULL, 0); goto out_restore_iov; out: @@ -1807,10 +1810,11 @@ static void tcp_data_from_tap(struct ctx *c, struct tcp_tap_conn *conn, struct tap_msg *msg, int count, struct timespec *now) { + int i, iov_i, keep = -1, ack = 0, fin = 0, retr = 0; struct msghdr mh = { .msg_iov = tcp_tap_iov }; uint32_t max_ack_seq = conn->seq_ack_from_tap; uint32_t seq_from_tap = conn->seq_from_tap; - int i, iov_i, keep = -1, ack = 0, fin = 0; + uint16_t max_ack_seq_wnd; ssize_t len; for (i = 0, iov_i = 0; i < count; i++) { @@ -1840,17 +1844,33 @@ static void tcp_data_from_tap(struct ctx *c, struct tcp_tap_conn *conn, seq = ntohl(th->seq); ack_seq = ntohl(th->ack_seq); + if (!i) { + if (count == 1) + max_ack_seq_wnd = ntohs(th->window); + else + max_ack_seq_wnd = ntohs(th->window) - 1; + } if (th->ack) { ack = 1; if (ack_seq - conn->seq_ack_from_tap < MAX_WINDOW && - ack_seq - max_ack_seq < MAX_WINDOW) + ack_seq - max_ack_seq < MAX_WINDOW) { + + /* Fast re-transmit */ + retr = !len && ack_seq == max_ack_seq && + max_ack_seq_wnd == ntohs(th->window); + + max_ack_seq_wnd = ntohs(th->window); max_ack_seq = ack_seq; + } } if (th->fin) fin = 1; + if (!len) + continue; + seq_offset = seq_from_tap - seq; /* Use data from this buffer only in these two cases: * @@ -1858,7 +1878,6 @@ static void tcp_data_from_tap(struct ctx *c, struct tcp_tap_conn *conn, * |--------| <-- len |--------| <-- len * '----' <-- offset ' <-- offset * ^ seq ^ seq - * * (offset >= 0, seq + len > seq_from_tap) * * discard in these two cases: @@ -1900,6 +1919,11 @@ static void tcp_data_from_tap(struct ctx *c, struct tcp_tap_conn *conn, tcp_sock_consume(conn, max_ack_seq); } + if (retr) { + conn->seq_to_tap = max_ack_seq; + tcp_data_from_sock(c, conn, now); + } + if (!iov_i) { if (keep != -1) { tcp_send_to_tap(c, conn, ACK, NULL, 0); @@ -1926,7 +1950,8 @@ static void tcp_data_from_tap(struct ctx *c, struct tcp_tap_conn *conn, } conn->seq_from_tap += len; - tcp_send_to_tap(c, conn, 0, NULL, 0); + if (!fin) + tcp_send_to_tap(c, conn, 0, NULL, 0); fin: if (conn->state == ESTABLISHED_SOCK_FIN && ack && @@ -1935,11 +1960,12 @@ fin: if (fin) { shutdown(conn->sock, SHUT_WR); - if (conn->state == ESTABLISHED) + if (conn->state == ESTABLISHED) { tcp_tap_state(conn, FIN_WAIT_1); - else + tcp_data_from_sock(c, conn, now); + } else { tcp_tap_state(conn, LAST_ACK); - return; + } } } @@ -2023,12 +2049,12 @@ int tcp_tap_handler(struct ctx *c, int af, void *addr, conn->seq_ack_to_tap = conn->seq_from_tap; tcp_tap_state(conn, ESTABLISHED); - tcp_send_to_tap(c, conn, ACK, NULL, 0); /* The client might have sent data already, which we didn't * dequeue waiting for SYN,ACK from tap -- check now. */ tcp_data_from_sock(c, conn, now); + tcp_send_to_tap(c, conn, 0, NULL, 0); ev.events = EPOLLIN | EPOLLET | EPOLLRDHUP; ref.s = conn->sock; @@ -2055,11 +2081,13 @@ int tcp_tap_handler(struct ctx *c, int af, void *addr, case CLOSE_WAIT: tcp_data_from_tap(c, conn, msg, count, now); return count; + case FIN_WAIT_1: + tcp_send_to_tap(c, conn, ACK, NULL, 0); + break; case FIN_WAIT_1_SOCK_FIN: if (th->ack) tcp_tap_destroy(c, conn); break; - case FIN_WAIT_1: case TAP_SYN_SENT: case LAST_ACK: case SPLICE_ACCEPTED: @@ -2570,9 +2598,9 @@ void tcp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events, tcp_tap_state(conn, FIN_WAIT_1_SOCK_FIN); shutdown(conn->sock, SHUT_RD); tcp_data_from_sock(c, conn, now); - tcp_send_to_tap(c, conn, FIN | ACK, NULL, 0); tcp_sock_consume(conn, conn->seq_ack_from_tap); - } else { + tcp_send_to_tap(c, conn, FIN | ACK, NULL, 0); + } else if (conn->state != ESTABLISHED_SOCK_FIN) { tcp_tap_destroy(c, conn); } } @@ -2731,7 +2759,7 @@ static void tcp_timer_one(struct ctx *c, struct tcp_tap_conn *conn, if (sock_ms > ACK_INTERVAL) { if (conn->seq_from_tap > conn->seq_ack_to_tap) - tcp_send_to_tap(c, conn, ACK, NULL, 0); + tcp_send_to_tap(c, conn, 0, NULL, 0); } if (ack_tap_ms > ACK_TIMEOUT) { -- cgit v1.2.3