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Date: Mon, 23 Jun 2008 15:20:57 -0700
From: "Adam Langley" <agl@...erialviolet.org>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org
Subject: [PATCH] TCP options clean up
From: Adam Langley <agl@...erialviolet.org>
TCP: options clean up
This should fix the following bugs:
* Connections with MD5 signatures produce invalid packets whenever SACK
options are included
* MD5 signatures are counted twice in the MSS calculations
Behaviour changes:
* A SYN with MD5 + SACK + TS elicits a SYNACK with MD5 + SACK
This is because we can't fit any SACK blocks in a packet with MD5 + TS
options. There was discussion about disabling SACK rather than TS in order
to fit in better with old, buggy kernels, but that was deemed to be
unnecessary.
* SYNs with MD5 don't include a TS option
See above.
Additionally, it removes a bunch of duplicated logic for calculating options,
which should help avoid these sort of issues in the future.
Signed-off-by: Adam Langley <agl@...erialviolet.org>
---
I wish that I could get diff to output bigger chunks. This diff is
pretty hard to read because of the many small chunks that diff finds.
Also, there will be a future patch to remove all of the max() calls in
tcp_input.c which are trying to calculate the number of SACK blocks that will
fit in a packet. This code subsumes that.
include/net/tcp.h | 2
net/ipv4/tcp_output.c | 426 +++++++++++++++++++++++++++----------------------
2 files changed, 234 insertions(+), 194 deletions(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 633147c..9164d2f 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -50,6 +50,7 @@ extern atomic_t tcp_orphan_count;
extern void tcp_time_wait(struct sock *sk, int state, int timeo);
#define MAX_TCP_HEADER (128 + MAX_HEADER)
+#define MAX_TCP_OPTION_SPACE 40
/*
* Never offer a window over 32767 without using window scaling. Some
@@ -185,6 +186,7 @@ extern void tcp_time_wait(struct sock *sk, int state, int timeo);
#define TCPOLEN_SACK_BASE_ALIGNED 4
#define TCPOLEN_SACK_PERBLOCK 8
#define TCPOLEN_MD5SIG_ALIGNED 20
+#define TCPOLEN_MSS_ALIGNED 4
/* Flags in tp->nonagle */
#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index e399bde..7ada03d 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -347,28 +347,81 @@ static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags)
TCP_SKB_CB(skb)->end_seq = seq;
}
-static void tcp_build_and_update_options(__be32 *ptr, struct tcp_sock *tp,
- __u32 tstamp, __u8 **md5_hash)
-{
- if (tp->rx_opt.tstamp_ok) {
+#define OPTION_SACK_ADVERTISE (1 << 0)
+#define OPTION_TS (1 << 1)
+#define OPTION_MD5 (1 << 2)
+
+struct tcp_out_options {
+ unsigned options; /* bit field of OPTION_* */
+ unsigned mss; /* 0 to disable */
+ unsigned ws; /* window scale, 0 to disable */
+ __u32 tsval, tsecr; /* need to include OPTION_TS */
+ unsigned num_sack_blocks; /* number of SACK blocks to include */
+};
+
+static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp,
+ const struct tcp_out_options *opts,
+ __u8 **md5_hash) {
+ if (unlikely(OPTION_MD5 & opts->options)) {
*ptr++ = htonl((TCPOPT_NOP << 24) |
(TCPOPT_NOP << 16) |
- (TCPOPT_TIMESTAMP << 8) |
- TCPOLEN_TIMESTAMP);
- *ptr++ = htonl(tstamp);
- *ptr++ = htonl(tp->rx_opt.ts_recent);
+ (TCPOPT_MD5SIG << 8) |
+ TCPOLEN_MD5SIG);
+ *md5_hash = (__u8 *)ptr;
+ ptr += 4;
+ } else {
+ *md5_hash = NULL;
+ }
+
+ if (likely(OPTION_TS & opts->options)) {
+ if (unlikely(OPTION_SACK_ADVERTISE & opts->options)) {
+ *ptr++ = htonl((TCPOPT_SACK_PERM << 24) |
+ (TCPOLEN_SACK_PERM << 16) |
+ (TCPOPT_TIMESTAMP << 8) |
+ TCPOLEN_TIMESTAMP);
+ } else {
+ *ptr++ = htonl((TCPOPT_NOP << 24) |
+ (TCPOPT_NOP << 16) |
+ (TCPOPT_TIMESTAMP << 8) |
+ TCPOLEN_TIMESTAMP);
+ }
+ *ptr++ = htonl(opts->tsval);
+ *ptr++ = htonl(opts->tsecr);
}
- if (tp->rx_opt.eff_sacks) {
- struct tcp_sack_block *sp = tp->rx_opt.dsack ? tp->duplicate_sack : tp->selective_acks;
+
+ if (unlikely(opts->mss)) {
+ *ptr++ = htonl((TCPOPT_MSS << 24) |
+ (TCPOLEN_MSS << 16) |
+ opts->mss);
+ }
+
+ if (unlikely(OPTION_SACK_ADVERTISE & opts->options &&
+ !(OPTION_TS & opts->options))) {
+ *ptr++ = htonl((TCPOPT_NOP << 24) |
+ (TCPOPT_NOP << 16) |
+ (TCPOPT_SACK_PERM << 8) |
+ TCPOLEN_SACK_PERM);
+ }
+
+ if (unlikely(opts->ws)) {
+ *ptr++ = htonl((TCPOPT_NOP << 24) |
+ (TCPOPT_WINDOW << 16) |
+ (TCPOLEN_WINDOW << 8) |
+ opts->ws);
+ }
+
+ if (unlikely(opts->num_sack_blocks)) {
+ struct tcp_sack_block *sp = tp->rx_opt.dsack ?
+ tp->duplicate_sack : tp->selective_acks;
int this_sack;
*ptr++ = htonl((TCPOPT_NOP << 24) |
(TCPOPT_NOP << 16) |
(TCPOPT_SACK << 8) |
- (TCPOLEN_SACK_BASE + (tp->rx_opt.eff_sacks *
+ (TCPOLEN_SACK_BASE + (opts->num_sack_blocks *
TCPOLEN_SACK_PERBLOCK)));
- for (this_sack = 0; this_sack < tp->rx_opt.eff_sacks; this_sack++) {
+ for (this_sack = 0; this_sack < opts->num_sack_blocks; ++this_sack) {
*ptr++ = htonl(sp[this_sack].start_seq);
*ptr++ = htonl(sp[this_sack].end_seq);
}
@@ -378,81 +431,137 @@ static void tcp_build_and_update_options(__be32 *ptr, struct tcp_sock *tp,
tp->rx_opt.eff_sacks--;
}
}
+}
+
+static unsigned tcp_syn_options(struct sock *sk, struct sk_buff *skb,
+ struct tcp_out_options *opts,
+ struct tcp_md5sig_key **md5) {
+ struct tcp_sock *tp = tcp_sk(sk);
+ unsigned size = 0;
+
#ifdef CONFIG_TCP_MD5SIG
- if (md5_hash) {
- *ptr++ = htonl((TCPOPT_NOP << 24) |
- (TCPOPT_NOP << 16) |
- (TCPOPT_MD5SIG << 8) |
- TCPOLEN_MD5SIG);
- *md5_hash = (__u8 *)ptr;
+ *md5 = tp->af_specific->md5_lookup(sk, sk);
+ if (*md5) {
+ opts->options |= OPTION_MD5;
+ size += TCPOLEN_MD5SIG_ALIGNED;
}
+#else
+ *md5 = NULL;
#endif
+
+ /* We always get an MSS option. The option bytes which will be seen in
+ * normal data packets should timestamps be used, must be in the MSS
+ * advertised. But we subtract them from tp->mss_cache so that
+ * calculations in tcp_sendmsg are simpler etc. So account for this
+ * fact here if necessary. If we don't do this correctly, as a
+ * receiver we won't recognize data packets as being full sized when we
+ * should, and thus we won't abide by the delayed ACK rules correctly.
+ * SACKs don't matter, we never delay an ACK when we have any of those
+ * going out. */
+ opts->mss = tcp_advertise_mss(sk);
+ size += TCPOLEN_MSS_ALIGNED;
+
+ if (likely(sysctl_tcp_timestamps && *md5 == NULL)) {
+ opts->options |= OPTION_TS;
+ opts->tsval = TCP_SKB_CB(skb)->when;
+ opts->tsecr = tp->rx_opt.ts_recent;
+ size += TCPOLEN_TSTAMP_ALIGNED;
+ }
+ if (likely(sysctl_tcp_window_scaling)) {
+ opts->ws = tp->rx_opt.rcv_wscale;
+ size += TCPOLEN_WSCALE_ALIGNED;
+ }
+ if (likely(sysctl_tcp_sack)) {
+ opts->options |= OPTION_SACK_ADVERTISE;
+ if (unlikely(!OPTION_TS & opts->options))
+ size += TCPOLEN_SACKPERM_ALIGNED;
+ }
+
+ return size;
}
-/* Construct a tcp options header for a SYN or SYN_ACK packet.
- * If this is every changed make sure to change the definition of
- * MAX_SYN_SIZE to match the new maximum number of options that you
- * can generate.
- *
- * Note - that with the RFC2385 TCP option, we make room for the
- * 16 byte MD5 hash. This will be filled in later, so the pointer for the
- * location to be filled is passed back up.
- */
-static void tcp_syn_build_options(__be32 *ptr, int mss, int ts, int sack,
- int offer_wscale, int wscale, __u32 tstamp,
- __u32 ts_recent, __u8 **md5_hash)
-{
- /* We always get an MSS option.
- * The option bytes which will be seen in normal data
- * packets should timestamps be used, must be in the MSS
- * advertised. But we subtract them from tp->mss_cache so
- * that calculations in tcp_sendmsg are simpler etc.
- * So account for this fact here if necessary. If we
- * don't do this correctly, as a receiver we won't
- * recognize data packets as being full sized when we
- * should, and thus we won't abide by the delayed ACK
- * rules correctly.
- * SACKs don't matter, we never delay an ACK when we
- * have any of those going out.
- */
- *ptr++ = htonl((TCPOPT_MSS << 24) | (TCPOLEN_MSS << 16) | mss);
- if (ts) {
- if (sack)
- *ptr++ = htonl((TCPOPT_SACK_PERM << 24) |
- (TCPOLEN_SACK_PERM << 16) |
- (TCPOPT_TIMESTAMP << 8) |
- TCPOLEN_TIMESTAMP);
- else
- *ptr++ = htonl((TCPOPT_NOP << 24) |
- (TCPOPT_NOP << 16) |
- (TCPOPT_TIMESTAMP << 8) |
- TCPOLEN_TIMESTAMP);
- *ptr++ = htonl(tstamp); /* TSVAL */
- *ptr++ = htonl(ts_recent); /* TSECR */
- } else if (sack)
- *ptr++ = htonl((TCPOPT_NOP << 24) |
- (TCPOPT_NOP << 16) |
- (TCPOPT_SACK_PERM << 8) |
- TCPOLEN_SACK_PERM);
- if (offer_wscale)
- *ptr++ = htonl((TCPOPT_NOP << 24) |
- (TCPOPT_WINDOW << 16) |
- (TCPOLEN_WINDOW << 8) |
- (wscale));
+static unsigned tcp_synack_options(struct sock *sk,
+ struct request_sock *req,
+ unsigned mss, struct sk_buff *skb,
+ struct tcp_out_options *opts,
+ struct tcp_md5sig_key **md5) {
+ unsigned size = 0;
+ struct inet_request_sock *ireq = inet_rsk(req);
+ char doing_ts;
+
#ifdef CONFIG_TCP_MD5SIG
- /*
- * If MD5 is enabled, then we set the option, and include the size
- * (always 18). The actual MD5 hash is added just before the
- * packet is sent.
- */
- if (md5_hash) {
- *ptr++ = htonl((TCPOPT_NOP << 24) |
- (TCPOPT_NOP << 16) |
- (TCPOPT_MD5SIG << 8) |
- TCPOLEN_MD5SIG);
- *md5_hash = (__u8 *)ptr;
+ *md5 = tcp_rsk(req)->af_specific->md5_lookup(sk, req);
+ if (*md5) {
+ opts->options |= OPTION_MD5;
+ size += TCPOLEN_MD5SIG_ALIGNED;
+ }
+#else
+ *md5 = NULL;
+#endif
+
+ /* we can't fit any SACK blocks in a packet with MD5 + TS
+ options. There was discussion about disabling SACK rather than TS in
+ order to fit in better with old, buggy kernels, but that was deemed
+ to be unnecessary. */
+ doing_ts = ireq->tstamp_ok && !(*md5 && ireq->sack_ok);
+
+ opts->mss = mss;
+ size += TCPOLEN_MSS_ALIGNED;
+
+ if (likely(ireq->wscale_ok)) {
+ opts->ws = ireq->rcv_wscale;
+ size += TCPOLEN_WSCALE_ALIGNED;
+ }
+ if (likely(doing_ts)) {
+ opts->options |= OPTION_TS;
+ opts->tsval = TCP_SKB_CB(skb)->when;
+ opts->tsecr = req->ts_recent;
+ size += TCPOLEN_TSTAMP_ALIGNED;
}
+ if (likely(ireq->sack_ok)) {
+ opts->options |= OPTION_SACK_ADVERTISE;
+ if (unlikely(!doing_ts))
+ size += TCPOLEN_SACKPERM_ALIGNED;
+ }
+
+ return size;
+}
+
+static unsigned tcp_established_options(struct sock *sk, struct sk_buff *skb,
+ struct tcp_out_options *opts,
+ struct tcp_md5sig_key **md5) {
+ struct tcp_skb_cb *tcb = skb ? TCP_SKB_CB(skb) : NULL;
+ struct tcp_sock *tp = tcp_sk(sk);
+ unsigned size = 0;
+
+#ifdef CONFIG_TCP_MD5SIG
+ *md5 = tp->af_specific->md5_lookup(sk, sk);
+ if (unlikely(*md5)) {
+ opts->options |= OPTION_MD5;
+ size += TCPOLEN_MD5SIG_ALIGNED;
+ }
+#else
+ *md5 = NULL;
#endif
+
+ if (likely(tp->rx_opt.tstamp_ok)) {
+ opts->options |= OPTION_TS;
+ opts->tsval = tcb ? tcb->when : 0;
+ opts->tsecr = tp->rx_opt.ts_recent;
+ size += TCPOLEN_TSTAMP_ALIGNED;
+ }
+
+ if (unlikely(tp->rx_opt.eff_sacks)) {
+ const unsigned remaining = MAX_TCP_OPTION_SPACE - size;
+ opts->num_sack_blocks =
+ min_t(unsigned, tp->rx_opt.eff_sacks,
+ (remaining - TCPOLEN_SACK_BASE_ALIGNED) /
+ TCPOLEN_SACK_PERBLOCK);
+ size += TCPOLEN_SACK_BASE_ALIGNED +
+ opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK;
+ }
+
+ return size;
}
/* This routine actually transmits TCP packets queued in by
@@ -473,13 +582,11 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
struct inet_sock *inet;
struct tcp_sock *tp;
struct tcp_skb_cb *tcb;
- int tcp_header_size;
-#ifdef CONFIG_TCP_MD5SIG
+ struct tcp_out_options opts;
+ unsigned tcp_options_size, tcp_header_size;
struct tcp_md5sig_key *md5;
__u8 *md5_hash_location;
-#endif
struct tcphdr *th;
- int sysctl_flags;
int err;
BUG_ON(!skb || !tcp_skb_pcount(skb));
@@ -502,50 +609,17 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
inet = inet_sk(sk);
tp = tcp_sk(sk);
tcb = TCP_SKB_CB(skb);
- tcp_header_size = tp->tcp_header_len;
-
-#define SYSCTL_FLAG_TSTAMPS 0x1
-#define SYSCTL_FLAG_WSCALE 0x2
-#define SYSCTL_FLAG_SACK 0x4
+ memset(&opts, 0, sizeof(opts));
- sysctl_flags = 0;
- if (unlikely(tcb->flags & TCPCB_FLAG_SYN)) {
- tcp_header_size = sizeof(struct tcphdr) + TCPOLEN_MSS;
- if (sysctl_tcp_timestamps) {
- tcp_header_size += TCPOLEN_TSTAMP_ALIGNED;
- sysctl_flags |= SYSCTL_FLAG_TSTAMPS;
- }
- if (sysctl_tcp_window_scaling) {
- tcp_header_size += TCPOLEN_WSCALE_ALIGNED;
- sysctl_flags |= SYSCTL_FLAG_WSCALE;
- }
- if (sysctl_tcp_sack) {
- sysctl_flags |= SYSCTL_FLAG_SACK;
- if (!(sysctl_flags & SYSCTL_FLAG_TSTAMPS))
- tcp_header_size += TCPOLEN_SACKPERM_ALIGNED;
- }
- } else if (unlikely(tp->rx_opt.eff_sacks)) {
- /* A SACK is 2 pad bytes, a 2 byte header, plus
- * 2 32-bit sequence numbers for each SACK block.
- */
- tcp_header_size += (TCPOLEN_SACK_BASE_ALIGNED +
- (tp->rx_opt.eff_sacks *
- TCPOLEN_SACK_PERBLOCK));
- }
+ if (unlikely(tcb->flags & TCPCB_FLAG_SYN))
+ tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5);
+ else
+ tcp_options_size = tcp_established_options(sk, skb, &opts, &md5);
+ tcp_header_size = tcp_options_size + sizeof(struct tcphdr);
if (tcp_packets_in_flight(tp) == 0)
tcp_ca_event(sk, CA_EVENT_TX_START);
-#ifdef CONFIG_TCP_MD5SIG
- /*
- * Are we doing MD5 on this segment? If so - make
- * room for it.
- */
- md5 = tp->af_specific->md5_lookup(sk, sk);
- if (md5)
- tcp_header_size += TCPOLEN_MD5SIG_ALIGNED;
-#endif
-
skb_push(skb, tcp_header_size);
skb_reset_transport_header(skb);
skb_set_owner_w(skb, sk);
@@ -576,29 +650,9 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
th->urg = 1;
}
- if (unlikely(tcb->flags & TCPCB_FLAG_SYN)) {
- tcp_syn_build_options((__be32 *)(th + 1),
- tcp_advertise_mss(sk),
- (sysctl_flags & SYSCTL_FLAG_TSTAMPS),
- (sysctl_flags & SYSCTL_FLAG_SACK),
- (sysctl_flags & SYSCTL_FLAG_WSCALE),
- tp->rx_opt.rcv_wscale,
- tcb->when,
- tp->rx_opt.ts_recent,
-
-#ifdef CONFIG_TCP_MD5SIG
- md5 ? &md5_hash_location :
-#endif
- NULL);
- } else {
- tcp_build_and_update_options((__be32 *)(th + 1),
- tp, tcb->when,
-#ifdef CONFIG_TCP_MD5SIG
- md5 ? &md5_hash_location :
-#endif
- NULL);
+ tcp_options_write((__be32 *)(th + 1), tp, &opts, &md5_hash_location);
+ if (likely((tcb->flags & TCPCB_FLAG_SYN) == 0))
TCP_ECN_send(sk, skb, tcp_header_size);
- }
#ifdef CONFIG_TCP_MD5SIG
/* Calculate the MD5 hash, as we have all we need now */
@@ -630,10 +684,6 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
tcp_enter_cwr(sk, 1);
return net_xmit_eval(err);
-
-#undef SYSCTL_FLAG_TSTAMPS
-#undef SYSCTL_FLAG_WSCALE
-#undef SYSCTL_FLAG_SACK
}
/* This routine just queue's the buffer
@@ -974,6 +1024,9 @@ unsigned int tcp_current_mss(struct sock *sk, int large_allowed)
u32 mss_now;
u16 xmit_size_goal;
int doing_tso = 0;
+ unsigned header_len;
+ struct tcp_out_options opts;
+ struct tcp_md5sig_key *md5;
mss_now = tp->mss_cache;
@@ -986,14 +1039,16 @@ unsigned int tcp_current_mss(struct sock *sk, int large_allowed)
mss_now = tcp_sync_mss(sk, mtu);
}
- if (tp->rx_opt.eff_sacks)
- mss_now -= (TCPOLEN_SACK_BASE_ALIGNED +
- (tp->rx_opt.eff_sacks * TCPOLEN_SACK_PERBLOCK));
-
-#ifdef CONFIG_TCP_MD5SIG
- if (tp->af_specific->md5_lookup(sk, sk))
- mss_now -= TCPOLEN_MD5SIG_ALIGNED;
-#endif
+ header_len = tcp_established_options(sk, NULL, &opts, &md5) +
+ sizeof(struct tcphdr);
+ /* The mss_cache is sized based on tp->tcp_header_len, which assumes
+ * some common options. If this is an odd packet (because we have SACK
+ * blocks etc) then our calculated header_len will be different, and
+ * we have to adjust mss_now correspondingly */
+ if (header_len != tp->tcp_header_len) {
+ int delta = (int) header_len - tp->tcp_header_len;
+ mss_now -= delta;
+ }
xmit_size_goal = mss_now;
@@ -2178,11 +2233,10 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
struct tcp_sock *tp = tcp_sk(sk);
struct tcphdr *th;
int tcp_header_size;
+ struct tcp_out_options opts;
struct sk_buff *skb;
-#ifdef CONFIG_TCP_MD5SIG
struct tcp_md5sig_key *md5;
__u8 *md5_hash_location;
-#endif
skb = sock_wmalloc(sk, MAX_TCP_HEADER + 15, 1, GFP_ATOMIC);
if (skb == NULL)
@@ -2193,18 +2247,26 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
skb->dst = dst_clone(dst);
- tcp_header_size = (sizeof(struct tcphdr) + TCPOLEN_MSS +
- (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0) +
- (ireq->wscale_ok ? TCPOLEN_WSCALE_ALIGNED : 0) +
- /* SACK_PERM is in the place of NOP NOP of TS */
- ((ireq->sack_ok && !ireq->tstamp_ok) ? TCPOLEN_SACKPERM_ALIGNED : 0));
+ if (req->rcv_wnd == 0) { /* ignored for retransmitted syns */
+ __u8 rcv_wscale;
+ /* Set this up on the first call only */
+ req->window_clamp = tp->window_clamp ? : dst_metric(dst, RTAX_WINDOW);
+ /* tcp_full_space because it is guaranteed to be the first packet */
+ tcp_select_initial_window(tcp_full_space(sk),
+ dst_metric(dst, RTAX_ADVMSS) - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0),
+ &req->rcv_wnd,
+ &req->window_clamp,
+ ireq->wscale_ok,
+ &rcv_wscale);
+ ireq->rcv_wscale = rcv_wscale;
+ }
+
+ memset(&opts, 0, sizeof(opts));
+ TCP_SKB_CB(skb)->when = tcp_time_stamp;
+ tcp_header_size = tcp_synack_options(sk, req, dst_metric(dst, RTAX_ADVMSS),
+ skb, &opts, &md5) +
+ sizeof(struct tcphdr);
-#ifdef CONFIG_TCP_MD5SIG
- /* Are we doing MD5 on this segment? If so - make room for it */
- md5 = tcp_rsk(req)->af_specific->md5_lookup(sk, req);
- if (md5)
- tcp_header_size += TCPOLEN_MD5SIG_ALIGNED;
-#endif
skb_push(skb, tcp_header_size);
skb_reset_transport_header(skb);
@@ -2222,19 +2284,6 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
TCPCB_FLAG_SYN | TCPCB_FLAG_ACK);
th->seq = htonl(TCP_SKB_CB(skb)->seq);
th->ack_seq = htonl(tcp_rsk(req)->rcv_isn + 1);
- if (req->rcv_wnd == 0) { /* ignored for retransmitted syns */
- __u8 rcv_wscale;
- /* Set this up on the first call only */
- req->window_clamp = tp->window_clamp ? : dst_metric(dst, RTAX_WINDOW);
- /* tcp_full_space because it is guaranteed to be the first packet */
- tcp_select_initial_window(tcp_full_space(sk),
- dst_metric(dst, RTAX_ADVMSS) - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0),
- &req->rcv_wnd,
- &req->window_clamp,
- ireq->wscale_ok,
- &rcv_wscale);
- ireq->rcv_wscale = rcv_wscale;
- }
/* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */
th->window = htons(min(req->rcv_wnd, 65535U));
@@ -2243,18 +2292,7 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
TCP_SKB_CB(skb)->when = cookie_init_timestamp(req);
else
#endif
- TCP_SKB_CB(skb)->when = tcp_time_stamp;
- tcp_syn_build_options((__be32 *)(th + 1), dst_metric(dst, RTAX_ADVMSS), ireq->tstamp_ok,
- ireq->sack_ok, ireq->wscale_ok, ireq->rcv_wscale,
- TCP_SKB_CB(skb)->when,
- req->ts_recent,
- (
-#ifdef CONFIG_TCP_MD5SIG
- md5 ? &md5_hash_location :
-#endif
- NULL)
- );
-
+ tcp_options_write((__be32 *)(th + 1), tp, &opts, &md5_hash_location);
th->doff = (tcp_header_size >> 2);
TCP_INC_STATS(TCP_MIB_OUTSEGS);
--
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