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-rw-r--r--tcp.c101
1 files changed, 64 insertions, 37 deletions
diff --git a/tcp.c b/tcp.c
index 093f95f..1aca1ac 100644
--- a/tcp.c
+++ b/tcp.c
@@ -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) {
generated by cgit v1.2.3 (git 2.25.1) at 2024-05-02 20:45:17 +0000