net: TCP_MSS_DEFAULT, TCP_MSS_DESIRED

Define two symbols needed in both kernel and user space.

Remove old (somewhat incorrect) kernel variant that wasn't used in
most cases.  Default should apply to both RMSS and SMSS (RFC2581).

Replace numeric constants with defined symbols.

Stand-alone patch, originally developed for TCPCT.

Signed-off-by: William.Allen.Simpson@gmail.com
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index eeecb8547a2a62b07b3e912cde8a4be496d322c2..32d7d77b4a012a97aec74bb45ade27fc795a9774 100644 (file)
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -81,6 +81,12 @@ enum {
        TCP_DATA_OFFSET = __cpu_to_be32(0xF0000000)
 }; 
 
+/*
+ * TCP general constants
+ */
+#define TCP_MSS_DEFAULT                 536U   /* IPv4 (RFC1122, RFC2581) */
+#define TCP_MSS_DESIRED                1220U   /* IPv6 (tunneled), EDNS0 (RFC3226) */
+
 /* TCP socket options */
 #define TCP_NODELAY            1       /* Turn off Nagle's algorithm. */
 #define TCP_MAXSEG             2       /* Limit MSS */

diff --git a/include/net/tcp.h b/include/net/tcp.h
index bf20f88fd0338cb7920eb505fc3c47e45d9591a7..325bfcf5c9342bd054c89085276ace06b913c624 100644 (file)
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -62,9 +62,6 @@ extern void tcp_time_wait(struct sock *sk, int state, int timeo);
 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */
 #define TCP_MIN_MSS            88U
 
-/* Minimal RCV_MSS. */
-#define TCP_MIN_RCVMSS         536U
-
 /* The least MTU to use for probing */
 #define TCP_BASE_MSS           512
 

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index be0c5bf7bfca50630e0091b3fb62c3020877edad..cc306ac6eb51b897418f60241a4c769df2b0df30 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -140,7 +140,7 @@ static void tcp_measure_rcv_mss(struct sock *sk, const struct sk_buff *skb)
                 * "len" is invariant segment length, including TCP header.
                 */
                len += skb->data - skb_transport_header(skb);
-               if (len >= TCP_MIN_RCVMSS + sizeof(struct tcphdr) ||
+               if (len >= TCP_MSS_DEFAULT + sizeof(struct tcphdr) ||
                    /* If PSH is not set, packet should be
                     * full sized, provided peer TCP is not badly broken.
                     * This observation (if it is correct 8)) allows
@@ -411,7 +411,7 @@ void tcp_initialize_rcv_mss(struct sock *sk)
        unsigned int hint = min_t(unsigned int, tp->advmss, tp->mss_cache);
 
        hint = min(hint, tp->rcv_wnd / 2);
-       hint = min(hint, TCP_MIN_RCVMSS);
+       hint = min(hint, TCP_MSS_DEFAULT);
        hint = max(hint, TCP_MIN_MSS);
 
        inet_csk(sk)->icsk_ack.rcv_mss = hint;

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 657ae334f12517fc5ee45e83abb76d1097615496..cf7f2086e6e05265f550ca25bdfd82b5bec1c80e 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -217,7 +217,7 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
        if (inet->opt)
                inet_csk(sk)->icsk_ext_hdr_len = inet->opt->optlen;
 
-       tp->rx_opt.mss_clamp = 536;
+       tp->rx_opt.mss_clamp = TCP_MSS_DEFAULT;
 
        /* Socket identity is still unknown (sport may be zero).
         * However we set state to SYN-SENT and not releasing socket
@@ -1268,7 +1268,7 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
                goto drop_and_free;
 
        tcp_clear_options(&tmp_opt);
-       tmp_opt.mss_clamp = 536;
+       tmp_opt.mss_clamp = TCP_MSS_DEFAULT;
        tmp_opt.user_mss  = tcp_sk(sk)->rx_opt.user_mss;
 
        tcp_parse_options(skb, &tmp_opt, 0, dst);
@@ -1815,7 +1815,7 @@ static int tcp_v4_init_sock(struct sock *sk)
         */
        tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
        tp->snd_cwnd_clamp = ~0;
-       tp->mss_cache = 536;
+       tp->mss_cache = TCP_MSS_DEFAULT;
 
        tp->reordering = sysctl_tcp_reordering;
        icsk->icsk_ca_ops = &tcp_init_congestion_ops;

diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index a9d34e224cb679720906792776daa8fec02ad068..4be22280e6b364e8807e44bd3e53aa221680100d 100644 (file)
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -476,7 +476,7 @@ struct sock *tcp_create_openreq_child(struct sock *sk, struct request_sock *req,
                if (newtp->af_specific->md5_lookup(sk, newsk))
                        newtp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED;
 #endif
-               if (skb->len >= TCP_MIN_RCVMSS+newtp->tcp_header_len)
+               if (skb->len >= TCP_MSS_DEFAULT + newtp->tcp_header_len)
                        newicsk->icsk_ack.last_seg_size = skb->len - newtp->tcp_header_len;
                newtp->rx_opt.mss_clamp = req->mss;
                TCP_ECN_openreq_child(newtp, req);

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 696a22f034e823bbd44527945ee63e9dbdbf1d6f..de709091b26d278e86a0fd4bb15b8ab380186f1d 100644 (file)
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1851,7 +1851,7 @@ static int tcp_v6_init_sock(struct sock *sk)
         */
        tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
        tp->snd_cwnd_clamp = ~0;
-       tp->mss_cache = 536;
+       tp->mss_cache = TCP_MSS_DEFAULT;
 
        tp->reordering = sysctl_tcp_reordering;