diff options
| -rw-r--r-- | tcp.c | 101 |
1 files changed, 64 insertions, 37 deletions
@@ -601,7 +601,12 @@ static struct iovec tcp6_l2_iov_tap [TCP_TAP_FRAMES]; static struct msghdr tcp4_l2_mh_sock; static struct msghdr tcp6_l2_mh_sock; -static struct mmsghdr tcp_l2_mh_tap [TCP_TAP_FRAMES]; +__extension__ +static struct mmsghdr tcp_l2_mh_tap [TCP_TAP_FRAMES] = { + [ 0 ... TCP_TAP_FRAMES - 1 ] = { + .msg_hdr.msg_iovlen = 1, + }, +}; /* sendmsg() to socket */ static struct iovec tcp_tap_iov [TAP_MSGS]; @@ -1358,8 +1363,15 @@ static void tcp_conn_from_tap(struct ctx *c, int af, void *addr, if (conn->mss_guest < 0) conn->mss_guest = MSS_DEFAULT; - if (c->mode == MODE_PASST && c->v6 && conn->mss_guest > SHRT_MAX) - conn->mss_guest = SHRT_MAX; + if (c->mode == MODE_PASST) { + /* Don't upset qemu */ + conn->mss_guest = MIN(USHRT_MAX - + sizeof(uint32_t) - + sizeof(struct ethhdr) - + sizeof(struct ipv6hdr) - + sizeof(struct tcphdr), + conn->mss_guest); + } sl = sizeof(conn->mss_guest); setsockopt(s, SOL_TCP, TCP_MAXSEG, &conn->mss_guest, sl); @@ -1534,15 +1546,16 @@ static void tcp_sock_consume(struct tcp_tap_conn *conn, uint32_t ack_seq) static int tcp_data_from_sock(struct ctx *c, struct tcp_tap_conn *conn, struct timespec *now) { - int mss_tap, fill_bufs, send_bufs = 0, last_len, msg_len, iov_rem = 0; int *buf_mss, *buf_mss_nr_set, *buf_mss_tap, *buf_mss_tap_nr_set; + int mss_tap, fill_bufs, send_bufs = 0, last_len, iov_rem = 0; int send, len, plen, v4 = IN6_IS_ADDR_V4MAPPED(&conn->a.a6); + uint32_t seq_to_tap = conn->seq_to_tap; socklen_t sl = sizeof(struct tcp_info); - struct mmsghdr *mh = tcp_l2_mh_tap; int s = conn->sock, i, ret = 0; struct iovec *iov, *iov_tap; uint32_t already_sent; struct tcp_info info; + struct mmsghdr *mh; already_sent = conn->seq_to_tap - conn->seq_ack_from_tap; @@ -1644,15 +1657,9 @@ static int tcp_data_from_sock(struct ctx *c, struct tcp_tap_conn *conn, info.tcpi_snd_wnd = conn->tcpi_snd_wnd; } - if (v4) - mh->msg_hdr.msg_iov = tcp4_l2_iov_tap; - else - mh->msg_hdr.msg_iov = tcp6_l2_iov_tap; - mh->msg_hdr.msg_iovlen = 0; plen = conn->mss_guest; - msg_len = 0; - for (i = 0; i < send_bufs; i++) { - int iov_len, ip_len; + for (i = 0, mh = tcp_l2_mh_tap; i < send_bufs; i++, mh++) { + int ip_len; if (i == send_bufs - 1) plen = last_len; @@ -1673,7 +1680,7 @@ static int tcp_data_from_sock(struct ctx *c, struct tcp_tap_conn *conn, b->th.source = htons(conn->sock_port); b->th.dest = htons(conn->tap_port); - b->th.seq = htonl(conn->seq_to_tap); + b->th.seq = htonl(seq_to_tap); b->th.ack_seq = htonl(conn->seq_ack_to_tap); if (conn->no_snd_wnd) { @@ -1696,6 +1703,8 @@ static int tcp_data_from_sock(struct ctx *c, struct tcp_tap_conn *conn, } b->vnet_len = htonl(sizeof(struct ethhdr) + ip_len); + + mh->msg_hdr.msg_iov = &tcp4_l2_iov_tap[i]; } else { struct tcp6_l2_buf_t *b = &tcp6_l2_buf[i]; uint32_t flow = conn->seq_init_to_tap; @@ -1713,7 +1722,7 @@ static int tcp_data_from_sock(struct ctx *c, struct tcp_tap_conn *conn, b->th.source = htons(conn->sock_port); b->th.dest = htons(conn->tap_port); - b->th.seq = htonl(conn->seq_to_tap); + b->th.seq = htonl(seq_to_tap); b->th.ack_seq = htonl(conn->seq_ack_to_tap); if (conn->no_snd_wnd) { @@ -1741,32 +1750,45 @@ static int tcp_data_from_sock(struct ctx *c, struct tcp_tap_conn *conn, } b->vnet_len = htonl(sizeof(struct ethhdr) + ip_len); - } - iov_len = sizeof(uint32_t) + sizeof(struct ethhdr) + ip_len; - - /* Switch to a new message if this one is too long for qemu. */ - if (msg_len && msg_len + iov_len > SHRT_MAX) { - mh++; - mh->msg_hdr.msg_iovlen = 0; - msg_len = 0; - if (v4) - mh->msg_hdr.msg_iov = &tcp4_l2_iov_tap[i]; - else - mh->msg_hdr.msg_iov = &tcp6_l2_iov_tap[i]; + mh->msg_hdr.msg_iov = &tcp6_l2_iov_tap[i]; } - mh->msg_hdr.msg_iovlen++; - msg_len += iov_len; - conn->seq_to_tap += plen; + seq_to_tap += plen; } if (c->mode == MODE_PASTA) goto out; - sendmmsg(c->fd_tap, tcp_l2_mh_tap, mh - tcp_l2_mh_tap + 1, - MSG_NOSIGNAL | MSG_DONTWAIT); - pcapmm(tcp_l2_mh_tap, mh - tcp_l2_mh_tap + 1); + ret = sendmmsg(c->fd_tap, tcp_l2_mh_tap, mh - tcp_l2_mh_tap, + MSG_NOSIGNAL | MSG_DONTWAIT); + if (ret <= 0) + goto out; + + conn->seq_to_tap += conn->mss_guest * (ret - 1) + last_len; + + /* sendmmsg() indicates how many messages were sent at least partially. + * Kernel commit 3023898b7d4a ("sock: fix sendmmsg for partial sendmsg") + * gives us the guarantee that at most one message, namely the last sent + * one, might have been sent partially. Check how many bytes of that + * message were sent, and re-send any missing bytes with a blocking + * sendmsg(), otherwise qemu will fail to parse any subsequent message. + */ + mh = &tcp_l2_mh_tap[ret - 1]; + if (mh->msg_len < mh->msg_hdr.msg_iov->iov_len) { + uint8_t **iov_base = (uint8_t **)&mh->msg_hdr.msg_iov->iov_base; + int part_sent = mh->msg_len; + + mh->msg_hdr.msg_iov->iov_len -= part_sent; + *iov_base += part_sent; + + sendmsg(c->fd_tap, &mh->msg_hdr, MSG_NOSIGNAL); + + mh->msg_hdr.msg_iov->iov_len += part_sent; + *iov_base -= part_sent; + } + + pcapmm(tcp_l2_mh_tap, ret); goto out; @@ -2027,10 +2049,15 @@ int tcp_tap_handler(struct ctx *c, int af, void *addr, if (conn->mss_guest < 0) conn->mss_guest = MSS_DEFAULT; - /* Don't upset qemu */ - if (c->mode == MODE_PASST && c->v6 && - conn->mss_guest > SHRT_MAX) - conn->mss_guest = SHRT_MAX; + if (c->mode == MODE_PASST) { + /* Don't upset qemu */ + conn->mss_guest = MIN(USHRT_MAX - + sizeof(uint32_t) - + sizeof(struct ethhdr) - + sizeof(struct ipv6hdr) - + sizeof(struct tcphdr), + conn->mss_guest); + } ws = tcp_opt_get(th, len, OPT_WS, NULL, NULL); if (ws > MAX_WS) { |