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tcp: extract buffer management from tcp_send_flag()

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Signed-off-by: Laurent Vivier <lvivier@redhat.com>
This commit is contained in:
Laurent Vivier 2023-10-12 11:46:34 +02:00
parent a66fceb280
commit 576c1cca2c
1 changed files with 72 additions and 72 deletions
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144
tcp.c
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@ -1358,40 +1358,6 @@ static size_t tcp_fill_headers6(const struct ctx *c,
return ip_len;
}
/**
* tcp_l2_buf_fill_headers() - Fill 802.3, IP, TCP headers in pre-cooked buffers
* @c: Execution context
* @conn: Connection pointer
* @iov: Pointer to an array of iovec of TCP pre-cooked buffer
* @plen: Payload length (including TCP header options)
* @check: Checksum, if already known
* @seq: Sequence number for this segment
*
* Return: frame length including L2 headers, host order
*/
static size_t tcp_l2_buf_fill_headers(const struct ctx *c,
const struct tcp_tap_conn *conn,
struct iovec *iov, size_t plen,
const uint16_t *check, uint32_t seq)
{
const struct in_addr *a4 = inany_v4(&conn->faddr);
size_t ip_len, tlen;
if (a4) {
ip_len = tcp_fill_headers4(c, conn, iov[TCP_IOV_IP].iov_base,
iov[TCP_IOV_PAYLOAD].iov_base, plen,
check, seq);
tlen = ip_len - sizeof(struct iphdr);
} else {
ip_len = tcp_fill_headers6(c, conn, iov[TCP_IOV_IP].iov_base,
iov[TCP_IOV_PAYLOAD].iov_base, plen,
seq);
tlen = ip_len - sizeof(struct ipv6hdr);
}
return tlen;
}
/**
* tcp_update_seqack_wnd() - Update ACK sequence and window to guest/tap
* @c: Execution context
@ -1509,26 +1475,27 @@ static void tcp_update_seqack_from_tap(const struct ctx *c,
}
/**
* tcp_send_flag() - Send segment with flags to tap (no payload)
* tcp_fill_flag_header() - Prepare header for flags-only segment (no payload)
* @c: Execution context
* @conn: Connection pointer
* @flags: TCP flags: if not set, send segment only if ACK is due
* @th: TCP header to update
* @opts: buffer to store TCP option
* @optlen: size of the TCP option buffer
*
* Return: negative error code on connection reset, 0 otherwise
* Return: < 0 error code on connection reset,
* 0 if there is no flag to send
* 1 otherwise
*/
static int tcp_send_flag(struct ctx *c, struct tcp_tap_conn *conn, int flags)
static int tcp_fill_flag_header(struct ctx *c, struct tcp_tap_conn *conn,
int flags, struct tcphdr *th, char *opts,
size_t *optlen)
{
uint32_t prev_ack_to_tap = conn->seq_ack_to_tap;
uint32_t prev_wnd_to_tap = conn->wnd_to_tap;
struct tcp_l2_flags_t *payload;
struct tcp_info tinfo = { 0 };
socklen_t sl = sizeof(tinfo);
int s = conn->sock;
size_t optlen = 0;
struct iovec *iov;
struct iovec *dup_iov;
struct tcphdr *th;
char *data;
if (SEQ_GE(conn->seq_ack_to_tap, conn->seq_from_tap) &&
!flags && conn->wnd_to_tap)
@ -1550,25 +1517,14 @@ static int tcp_send_flag(struct ctx *c, struct tcp_tap_conn *conn, int flags)
if (!tcp_update_seqack_wnd(c, conn, flags, &tinfo) && !flags)
return 0;
if (CONN_V4(conn)) {
iov = tcp4_l2_flags_iov[tcp4_l2_flags_buf_used++];
dup_iov = tcp4_l2_flags_iov[tcp4_l2_flags_buf_used];
} else {
iov = tcp6_l2_flags_iov[tcp6_l2_flags_buf_used++];
dup_iov = tcp6_l2_flags_iov[tcp6_l2_flags_buf_used];
}
payload = iov[TCP_IOV_PAYLOAD].iov_base;
th = &payload->th;
data = payload->opts;
if (flags & SYN) {
int mss;
/* Options: MSS, NOP and window scale (8 bytes) */
optlen = OPT_MSS_LEN + 1 + OPT_WS_LEN;
*optlen = OPT_MSS_LEN + 1 + OPT_WS_LEN;
*data++ = OPT_MSS;
*data++ = OPT_MSS_LEN;
*opts++ = OPT_MSS;
*opts++ = OPT_MSS_LEN;
if (c->mtu == -1) {
mss = tinfo.tcpi_snd_mss;
@ -1581,16 +1537,16 @@ static int tcp_send_flag(struct ctx *c, struct tcp_tap_conn *conn, int flags)
else if (mss > PAGE_SIZE)
mss = ROUND_DOWN(mss, PAGE_SIZE);
}
*(uint16_t *)data = htons(MIN(USHRT_MAX, mss));
*(uint16_t *)opts = htons(MIN(USHRT_MAX, mss));
data += OPT_MSS_LEN - 2;
opts += OPT_MSS_LEN - 2;
conn->ws_to_tap = MIN(MAX_WS, tinfo.tcpi_snd_wscale);
*data++ = OPT_NOP;
*data++ = OPT_WS;
*data++ = OPT_WS_LEN;
*data++ = conn->ws_to_tap;
*opts++ = OPT_NOP;
*opts++ = OPT_WS;
*opts++ = OPT_WS_LEN;
*opts++ = conn->ws_to_tap;
th->ack = !!(flags & ACK);
} else {
@ -1599,16 +1555,12 @@ static int tcp_send_flag(struct ctx *c, struct tcp_tap_conn *conn, int flags)
!prev_wnd_to_tap;
}
th->doff = (sizeof(*th) + optlen) / 4;
th->doff = (sizeof(*th) + *optlen) / 4;
th->rst = !!(flags & RST);
th->syn = !!(flags & SYN);
th->fin = !!(flags & FIN);
iov[TCP_IOV_PAYLOAD].iov_len = tcp_l2_buf_fill_headers(c, conn, iov,
optlen, NULL,
conn->seq_to_tap);
if (th->ack) {
if (SEQ_GE(conn->seq_ack_to_tap, conn->seq_from_tap))
conn_flag(c, conn, ~ACK_TO_TAP_DUE);
@ -1623,6 +1575,48 @@ static int tcp_send_flag(struct ctx *c, struct tcp_tap_conn *conn, int flags)
if (th->fin || th->syn)
conn->seq_to_tap++;
return 1;
}
static int tcp_send_flag(struct ctx *c, struct tcp_tap_conn *conn, int flags)
{
struct tcp_l2_flags_t *payload;
struct iovec *dup_iov;
struct iovec *iov;
struct tcphdr *th;
size_t optlen = 0;
size_t ip_len;
char *data;
int ret;
if (CONN_V4(conn)) {
iov = tcp4_l2_flags_iov[tcp4_l2_flags_buf_used++];
dup_iov = tcp4_l2_flags_iov[tcp4_l2_flags_buf_used];
} else {
iov = tcp6_l2_flags_iov[tcp6_l2_flags_buf_used++];
dup_iov = tcp6_l2_flags_iov[tcp6_l2_flags_buf_used];
}
payload = iov[TCP_IOV_PAYLOAD].iov_base;
th = &payload->th;
data = payload->opts;
ret = tcp_fill_flag_header(c, conn, flags, th, data, &optlen);
if (ret <= 0)
return ret;
if (CONN_V4(conn)) {
struct iphdr *iph = iov[TCP_IOV_IP].iov_base;
ip_len = tcp_fill_headers4(c, conn, iph, th, optlen, NULL,
conn->seq_to_tap);
} else {
struct ipv6hdr *ip6h = iov[TCP_IOV_IP].iov_base;
ip_len = tcp_fill_headers6(c, conn, ip6h, th, optlen,
conn->seq_to_tap);
}
iov[TCP_IOV_PAYLOAD].iov_len = ip_len;
if (flags & DUP_ACK) {
int i;
for (i = 0; i < TCP_IOV_NUM; i++) {
@ -2103,8 +2097,11 @@ static void tcp_data_to_tap(const struct ctx *c, struct tcp_tap_conn *conn,
tcp4_l2_buf_seq_update[tcp4_l2_buf_used].len = plen;
iov = tcp4_l2_iov[tcp4_l2_buf_used++];
iov[TCP_IOV_PAYLOAD].iov_len = tcp_l2_buf_fill_headers(c, conn,
iov, plen, check, seq);
iov[TCP_IOV_PAYLOAD].iov_len = tcp_fill_headers4(c, conn,
iov[TCP_IOV_IP].iov_base,
iov[TCP_IOV_PAYLOAD].iov_base,
plen, check, seq);
if (tcp4_l2_buf_used > TCP_FRAMES_MEM - 1)
tcp_l2_data_buf_flush(c);
} else if (CONN_V6(conn)) {
@ -2112,8 +2109,11 @@ static void tcp_data_to_tap(const struct ctx *c, struct tcp_tap_conn *conn,
tcp6_l2_buf_seq_update[tcp6_l2_buf_used].len = plen;
iov = tcp6_l2_iov[tcp6_l2_buf_used++];
iov[TCP_IOV_PAYLOAD].iov_len = tcp_l2_buf_fill_headers(c, conn,
iov, plen, NULL, seq);
iov[TCP_IOV_PAYLOAD].iov_len = tcp_fill_headers6(c, conn,
iov[TCP_IOV_IP].iov_base,
iov[TCP_IOV_PAYLOAD].iov_base,
plen, seq);
if (tcp6_l2_buf_used > TCP_FRAMES_MEM - 1)
tcp_l2_data_buf_flush(c);
}