/* $NetBSD: tcp_subr.c,v 1.214 2007/05/02 20:40:25 dyoung Exp $ */ /* * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the project nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ /*- * Copyright (c) 1997, 1998, 2000, 2001 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Jason R. Thorpe and Kevin M. Lahey of the Numerical Aerospace Simulation * Facility, NASA Ames Research Center. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the NetBSD * Foundation, Inc. and its contributors. * 4. Neither the name of The NetBSD Foundation nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /* * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)tcp_subr.c 8.2 (Berkeley) 5/24/95 */ #include __KERNEL_RCSID(0, "$NetBSD: tcp_subr.c,v 1.214 2007/05/02 20:40:25 dyoung Exp $"); #include "opt_inet.h" #include "opt_ipsec.h" #include "opt_tcp_compat_42.h" #include "opt_inet_csum.h" #include "opt_mbuftrace.h" #include "rnd.h" #include #include #include #include #include #include #include #include #include #include #include #if NRND > 0 #include #include #endif #include #include #include #include #include #include #include #include #ifdef INET6 #ifndef INET #include #endif #include #include #include #include #include #include #include #endif #include #include #include #include #include #include #include #ifdef IPSEC #include #include #endif /*IPSEC*/ #ifdef FAST_IPSEC #include #include #ifdef INET6 #include #endif #include #endif /* FAST_IPSEC*/ struct inpcbtable tcbtable; /* head of queue of active tcpcb's */ struct tcpstat tcpstat; /* tcp statistics */ u_int32_t tcp_now; /* for RFC 1323 timestamps */ /* patchable/settable parameters for tcp */ int tcp_mssdflt = TCP_MSS; int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ; int tcp_do_rfc1323 = 1; /* window scaling / timestamps (obsolete) */ #if NRND > 0 int tcp_do_rfc1948 = 0; /* ISS by cryptographic hash */ #endif int tcp_do_sack = 1; /* selective acknowledgement */ int tcp_do_win_scale = 1; /* RFC1323 window scaling */ int tcp_do_timestamps = 1; /* RFC1323 timestamps */ int tcp_ack_on_push = 0; /* set to enable immediate ACK-on-PUSH */ int tcp_do_ecn = 0; /* Explicit Congestion Notification */ #ifndef TCP_INIT_WIN #define TCP_INIT_WIN 0 /* initial slow start window */ #endif #ifndef TCP_INIT_WIN_LOCAL #define TCP_INIT_WIN_LOCAL 4 /* initial slow start window for local nets */ #endif int tcp_init_win = TCP_INIT_WIN; int tcp_init_win_local = TCP_INIT_WIN_LOCAL; int tcp_mss_ifmtu = 0; #ifdef TCP_COMPAT_42 int tcp_compat_42 = 1; #else int tcp_compat_42 = 0; #endif int tcp_rst_ppslim = 100; /* 100pps */ int tcp_ackdrop_ppslim = 100; /* 100pps */ int tcp_do_loopback_cksum = 0; int tcp_do_abc = 1; /* RFC3465 Appropriate byte counting. */ int tcp_abc_aggressive = 1; /* 1: L=2*SMSS 0: L=1*SMSS */ int tcp_sack_tp_maxholes = 32; int tcp_sack_globalmaxholes = 1024; int tcp_sack_globalholes = 0; int tcp_ecn_maxretries = 1; /* tcb hash */ #ifndef TCBHASHSIZE #define TCBHASHSIZE 128 #endif int tcbhashsize = TCBHASHSIZE; /* syn hash parameters */ #define TCP_SYN_HASH_SIZE 293 #define TCP_SYN_BUCKET_SIZE 35 int tcp_syn_cache_size = TCP_SYN_HASH_SIZE; int tcp_syn_cache_limit = TCP_SYN_HASH_SIZE*TCP_SYN_BUCKET_SIZE; int tcp_syn_bucket_limit = 3*TCP_SYN_BUCKET_SIZE; struct syn_cache_head tcp_syn_cache[TCP_SYN_HASH_SIZE]; int tcp_freeq(struct tcpcb *); #ifdef INET void tcp_mtudisc_callback(struct in_addr); #endif #ifdef INET6 void tcp6_mtudisc_callback(struct in6_addr *); #endif #ifdef INET6 void tcp6_mtudisc(struct in6pcb *, int); #endif POOL_INIT(tcpcb_pool, sizeof(struct tcpcb), 0, 0, 0, "tcpcbpl", NULL, IPL_SOFTNET); #ifdef TCP_CSUM_COUNTERS #include #if defined(INET) struct evcnt tcp_hwcsum_bad = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, NULL, "tcp", "hwcsum bad"); struct evcnt tcp_hwcsum_ok = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, NULL, "tcp", "hwcsum ok"); struct evcnt tcp_hwcsum_data = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, NULL, "tcp", "hwcsum data"); struct evcnt tcp_swcsum = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, NULL, "tcp", "swcsum"); EVCNT_ATTACH_STATIC(tcp_hwcsum_bad); EVCNT_ATTACH_STATIC(tcp_hwcsum_ok); EVCNT_ATTACH_STATIC(tcp_hwcsum_data); EVCNT_ATTACH_STATIC(tcp_swcsum); #endif /* defined(INET) */ #if defined(INET6) struct evcnt tcp6_hwcsum_bad = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, NULL, "tcp6", "hwcsum bad"); struct evcnt tcp6_hwcsum_ok = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, NULL, "tcp6", "hwcsum ok"); struct evcnt tcp6_hwcsum_data = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, NULL, "tcp6", "hwcsum data"); struct evcnt tcp6_swcsum = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, NULL, "tcp6", "swcsum"); EVCNT_ATTACH_STATIC(tcp6_hwcsum_bad); EVCNT_ATTACH_STATIC(tcp6_hwcsum_ok); EVCNT_ATTACH_STATIC(tcp6_hwcsum_data); EVCNT_ATTACH_STATIC(tcp6_swcsum); #endif /* defined(INET6) */ #endif /* TCP_CSUM_COUNTERS */ #ifdef TCP_OUTPUT_COUNTERS #include struct evcnt tcp_output_bigheader = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, NULL, "tcp", "output big header"); struct evcnt tcp_output_predict_hit = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, NULL, "tcp", "output predict hit"); struct evcnt tcp_output_predict_miss = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, NULL, "tcp", "output predict miss"); struct evcnt tcp_output_copysmall = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, NULL, "tcp", "output copy small"); struct evcnt tcp_output_copybig = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, NULL, "tcp", "output copy big"); struct evcnt tcp_output_refbig = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, NULL, "tcp", "output reference big"); EVCNT_ATTACH_STATIC(tcp_output_bigheader); EVCNT_ATTACH_STATIC(tcp_output_predict_hit); EVCNT_ATTACH_STATIC(tcp_output_predict_miss); EVCNT_ATTACH_STATIC(tcp_output_copysmall); EVCNT_ATTACH_STATIC(tcp_output_copybig); EVCNT_ATTACH_STATIC(tcp_output_refbig); #endif /* TCP_OUTPUT_COUNTERS */ #ifdef TCP_REASS_COUNTERS #include struct evcnt tcp_reass_ = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, NULL, "tcp_reass", "calls"); struct evcnt tcp_reass_empty = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, &tcp_reass_, "tcp_reass", "insert into empty queue"); struct evcnt tcp_reass_iteration[8] = { EVCNT_INITIALIZER(EVCNT_TYPE_MISC, &tcp_reass_, "tcp_reass", ">7 iterations"), EVCNT_INITIALIZER(EVCNT_TYPE_MISC, &tcp_reass_, "tcp_reass", "1 iteration"), EVCNT_INITIALIZER(EVCNT_TYPE_MISC, &tcp_reass_, "tcp_reass", "2 iterations"), EVCNT_INITIALIZER(EVCNT_TYPE_MISC, &tcp_reass_, "tcp_reass", "3 iterations"), EVCNT_INITIALIZER(EVCNT_TYPE_MISC, &tcp_reass_, "tcp_reass", "4 iterations"), EVCNT_INITIALIZER(EVCNT_TYPE_MISC, &tcp_reass_, "tcp_reass", "5 iterations"), EVCNT_INITIALIZER(EVCNT_TYPE_MISC, &tcp_reass_, "tcp_reass", "6 iterations"), EVCNT_INITIALIZER(EVCNT_TYPE_MISC, &tcp_reass_, "tcp_reass", "7 iterations"), }; struct evcnt tcp_reass_prependfirst = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, &tcp_reass_, "tcp_reass", "prepend to first"); struct evcnt tcp_reass_prepend = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, &tcp_reass_, "tcp_reass", "prepend"); struct evcnt tcp_reass_insert = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, &tcp_reass_, "tcp_reass", "insert"); struct evcnt tcp_reass_inserttail = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, &tcp_reass_, "tcp_reass", "insert at tail"); struct evcnt tcp_reass_append = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, &tcp_reass_, "tcp_reass", "append"); struct evcnt tcp_reass_appendtail = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, &tcp_reass_, "tcp_reass", "append to tail fragment"); struct evcnt tcp_reass_overlaptail = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, &tcp_reass_, "tcp_reass", "overlap at end"); struct evcnt tcp_reass_overlapfront = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, &tcp_reass_, "tcp_reass", "overlap at start"); struct evcnt tcp_reass_segdup = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, &tcp_reass_, "tcp_reass", "duplicate segment"); struct evcnt tcp_reass_fragdup = EVCNT_INITIALIZER(EVCNT_TYPE_MISC, &tcp_reass_, "tcp_reass", "duplicate fragment"); EVCNT_ATTACH_STATIC(tcp_reass_); EVCNT_ATTACH_STATIC(tcp_reass_empty); EVCNT_ATTACH_STATIC2(tcp_reass_iteration, 0); EVCNT_ATTACH_STATIC2(tcp_reass_iteration, 1); EVCNT_ATTACH_STATIC2(tcp_reass_iteration, 2); EVCNT_ATTACH_STATIC2(tcp_reass_iteration, 3); EVCNT_ATTACH_STATIC2(tcp_reass_iteration, 4); EVCNT_ATTACH_STATIC2(tcp_reass_iteration, 5); EVCNT_ATTACH_STATIC2(tcp_reass_iteration, 6); EVCNT_ATTACH_STATIC2(tcp_reass_iteration, 7); EVCNT_ATTACH_STATIC(tcp_reass_prependfirst); EVCNT_ATTACH_STATIC(tcp_reass_prepend); EVCNT_ATTACH_STATIC(tcp_reass_insert); EVCNT_ATTACH_STATIC(tcp_reass_inserttail); EVCNT_ATTACH_STATIC(tcp_reass_append); EVCNT_ATTACH_STATIC(tcp_reass_appendtail); EVCNT_ATTACH_STATIC(tcp_reass_overlaptail); EVCNT_ATTACH_STATIC(tcp_reass_overlapfront); EVCNT_ATTACH_STATIC(tcp_reass_segdup); EVCNT_ATTACH_STATIC(tcp_reass_fragdup); #endif /* TCP_REASS_COUNTERS */ #ifdef MBUFTRACE struct mowner tcp_mowner = MOWNER_INIT("tcp", ""); struct mowner tcp_rx_mowner = MOWNER_INIT("tcp", "rx"); struct mowner tcp_tx_mowner = MOWNER_INIT("tcp", "tx"); struct mowner tcp_sock_mowner = MOWNER_INIT("tcp", "sock"); struct mowner tcp_sock_rx_mowner = MOWNER_INIT("tcp", "sock rx"); struct mowner tcp_sock_tx_mowner = MOWNER_INIT("tcp", "sock tx"); #endif /* * Tcp initialization */ void tcp_init(void) { int hlen; /* Initialize the TCPCB template. */ tcp_tcpcb_template(); in_pcbinit(&tcbtable, tcbhashsize, tcbhashsize); hlen = sizeof(struct ip) + sizeof(struct tcphdr); #ifdef INET6 if (sizeof(struct ip) < sizeof(struct ip6_hdr)) hlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); #endif if (max_protohdr < hlen) max_protohdr = hlen; if (max_linkhdr + hlen > MHLEN) panic("tcp_init"); #ifdef INET icmp_mtudisc_callback_register(tcp_mtudisc_callback); #endif #ifdef INET6 icmp6_mtudisc_callback_register(tcp6_mtudisc_callback); #endif /* Initialize timer state. */ tcp_timer_init(); /* Initialize the compressed state engine. */ syn_cache_init(); /* Initialize the congestion control algorithms. */ tcp_congctl_init(); MOWNER_ATTACH(&tcp_tx_mowner); MOWNER_ATTACH(&tcp_rx_mowner); MOWNER_ATTACH(&tcp_reass_mowner); MOWNER_ATTACH(&tcp_sock_mowner); MOWNER_ATTACH(&tcp_sock_tx_mowner); MOWNER_ATTACH(&tcp_sock_rx_mowner); MOWNER_ATTACH(&tcp_mowner); } /* * Create template to be used to send tcp packets on a connection. * Call after host entry created, allocates an mbuf and fills * in a skeletal tcp/ip header, minimizing the amount of work * necessary when the connection is used. */ struct mbuf * tcp_template(struct tcpcb *tp) { struct inpcb *inp = tp->t_inpcb; #ifdef INET6 struct in6pcb *in6p = tp->t_in6pcb; #endif struct tcphdr *n; struct mbuf *m; int hlen; switch (tp->t_family) { case AF_INET: hlen = sizeof(struct ip); if (inp) break; #ifdef INET6 if (in6p) { /* mapped addr case */ if (IN6_IS_ADDR_V4MAPPED(&in6p->in6p_laddr) && IN6_IS_ADDR_V4MAPPED(&in6p->in6p_faddr)) break; } #endif return NULL; /*EINVAL*/ #ifdef INET6 case AF_INET6: hlen = sizeof(struct ip6_hdr); if (in6p) { /* more sainty check? */ break; } return NULL; /*EINVAL*/ #endif default: hlen = 0; /*pacify gcc*/ return NULL; /*EAFNOSUPPORT*/ } #ifdef DIAGNOSTIC if (hlen + sizeof(struct tcphdr) > MCLBYTES) panic("mclbytes too small for t_template"); #endif m = tp->t_template; if (m && m->m_len == hlen + sizeof(struct tcphdr)) ; else { if (m) m_freem(m); m = tp->t_template = NULL; MGETHDR(m, M_DONTWAIT, MT_HEADER); if (m && hlen + sizeof(struct tcphdr) > MHLEN) { MCLGET(m, M_DONTWAIT); if ((m->m_flags & M_EXT) == 0) { m_free(m); m = NULL; } } if (m == NULL) return NULL; MCLAIM(m, &tcp_mowner); m->m_pkthdr.len = m->m_len = hlen + sizeof(struct tcphdr); } bzero(mtod(m, void *), m->m_len); n = (struct tcphdr *)(mtod(m, char *) + hlen); switch (tp->t_family) { case AF_INET: { struct ipovly *ipov; mtod(m, struct ip *)->ip_v = 4; mtod(m, struct ip *)->ip_hl = hlen >> 2; ipov = mtod(m, struct ipovly *); ipov->ih_pr = IPPROTO_TCP; ipov->ih_len = htons(sizeof(struct tcphdr)); if (inp) { ipov->ih_src = inp->inp_laddr; ipov->ih_dst = inp->inp_faddr; } #ifdef INET6 else if (in6p) { /* mapped addr case */ bcopy(&in6p->in6p_laddr.s6_addr32[3], &ipov->ih_src, sizeof(ipov->ih_src)); bcopy(&in6p->in6p_faddr.s6_addr32[3], &ipov->ih_dst, sizeof(ipov->ih_dst)); } #endif /* * Compute the pseudo-header portion of the checksum * now. We incrementally add in the TCP option and * payload lengths later, and then compute the TCP * checksum right before the packet is sent off onto * the wire. */ n->th_sum = in_cksum_phdr(ipov->ih_src.s_addr, ipov->ih_dst.s_addr, htons(sizeof(struct tcphdr) + IPPROTO_TCP)); break; } #ifdef INET6 case AF_INET6: { struct ip6_hdr *ip6; mtod(m, struct ip *)->ip_v = 6; ip6 = mtod(m, struct ip6_hdr *); ip6->ip6_nxt = IPPROTO_TCP; ip6->ip6_plen = htons(sizeof(struct tcphdr)); ip6->ip6_src = in6p->in6p_laddr; ip6->ip6_dst = in6p->in6p_faddr; ip6->ip6_flow = in6p->in6p_flowinfo & IPV6_FLOWINFO_MASK; if (ip6_auto_flowlabel) { ip6->ip6_flow &= ~IPV6_FLOWLABEL_MASK; ip6->ip6_flow |= (htonl(ip6_randomflowlabel()) & IPV6_FLOWLABEL_MASK); } ip6->ip6_vfc &= ~IPV6_VERSION_MASK; ip6->ip6_vfc |= IPV6_VERSION; /* * Compute the pseudo-header portion of the checksum * now. We incrementally add in the TCP option and * payload lengths later, and then compute the TCP * checksum right before the packet is sent off onto * the wire. */ n->th_sum = in6_cksum_phdr(&in6p->in6p_laddr, &in6p->in6p_faddr, htonl(sizeof(struct tcphdr)), htonl(IPPROTO_TCP)); break; } #endif } if (inp) { n->th_sport = inp->inp_lport; n->th_dport = inp->inp_fport; } #ifdef INET6 else if (in6p) { n->th_sport = in6p->in6p_lport; n->th_dport = in6p->in6p_fport; } #endif n->th_seq = 0; n->th_ack = 0; n->th_x2 = 0; n->th_off = 5; n->th_flags = 0; n->th_win = 0; n->th_urp = 0; return (m); } /* * Send a single message to the TCP at address specified by * the given TCP/IP header. If m == 0, then we make a copy * of the tcpiphdr at ti and send directly to the addressed host. * This is used to force keep alive messages out using the TCP * template for a connection tp->t_template. If flags are given * then we send a message back to the TCP which originated the * segment ti, and discard the mbuf containing it and any other * attached mbufs. * * In any case the ack and sequence number of the transmitted * segment are as specified by the parameters. */ int tcp_respond(struct tcpcb *tp, struct mbuf *template, struct mbuf *m, struct tcphdr *th0, tcp_seq ack, tcp_seq seq, int flags) { struct route *ro; int error, tlen, win = 0; int hlen; struct ip *ip; #ifdef INET6 struct ip6_hdr *ip6; #endif int family; /* family on packet, not inpcb/in6pcb! */ struct tcphdr *th; struct socket *so; if (tp != NULL && (flags & TH_RST) == 0) { #ifdef DIAGNOSTIC if (tp->t_inpcb && tp->t_in6pcb) panic("tcp_respond: both t_inpcb and t_in6pcb are set"); #endif #ifdef INET if (tp->t_inpcb) win = sbspace(&tp->t_inpcb->inp_socket->so_rcv); #endif #ifdef INET6 if (tp->t_in6pcb) win = sbspace(&tp->t_in6pcb->in6p_socket->so_rcv); #endif } th = NULL; /* Quell uninitialized warning */ ip = NULL; #ifdef INET6 ip6 = NULL; #endif if (m == 0) { if (!template) return EINVAL; /* get family information from template */ switch (mtod(template, struct ip *)->ip_v) { case 4: family = AF_INET; hlen = sizeof(struct ip); break; #ifdef INET6 case 6: family = AF_INET6; hlen = sizeof(struct ip6_hdr); break; #endif default: return EAFNOSUPPORT; } MGETHDR(m, M_DONTWAIT, MT_HEADER); if (m) { MCLAIM(m, &tcp_tx_mowner); MCLGET(m, M_DONTWAIT); if ((m->m_flags & M_EXT) == 0) { m_free(m); m = NULL; } } if (m == NULL) return (ENOBUFS); if (tcp_compat_42) tlen = 1; else tlen = 0; m->m_data += max_linkhdr; bcopy(mtod(template, void *), mtod(m, void *), template->m_len); switch (family) { case AF_INET: ip = mtod(m, struct ip *); th = (struct tcphdr *)(ip + 1); break; #ifdef INET6 case AF_INET6: ip6 = mtod(m, struct ip6_hdr *); th = (struct tcphdr *)(ip6 + 1); break; #endif #if 0 default: /* noone will visit here */ m_freem(m); return EAFNOSUPPORT; #endif } flags = TH_ACK; } else { if ((m->m_flags & M_PKTHDR) == 0) { #if 0 printf("non PKTHDR to tcp_respond\n"); #endif m_freem(m); return EINVAL; } #ifdef DIAGNOSTIC if (!th0) panic("th0 == NULL in tcp_respond"); #endif /* get family information from m */ switch (mtod(m, struct ip *)->ip_v) { case 4: family = AF_INET; hlen = sizeof(struct ip); ip = mtod(m, struct ip *); break; #ifdef INET6 case 6: family = AF_INET6; hlen = sizeof(struct ip6_hdr); ip6 = mtod(m, struct ip6_hdr *); break; #endif default: m_freem(m); return EAFNOSUPPORT; } /* clear h/w csum flags inherited from rx packet */ m->m_pkthdr.csum_flags = 0; if ((flags & TH_SYN) == 0 || sizeof(*th0) > (th0->th_off << 2)) tlen = sizeof(*th0); else tlen = th0->th_off << 2; if (m->m_len > hlen + tlen && (m->m_flags & M_EXT) == 0 && mtod(m, char *) + hlen == (char *)th0) { m->m_len = hlen + tlen; m_freem(m->m_next); m->m_next = NULL; } else { struct mbuf *n; #ifdef DIAGNOSTIC if (max_linkhdr + hlen + tlen > MCLBYTES) { m_freem(m); return EMSGSIZE; } #endif MGETHDR(n, M_DONTWAIT, MT_HEADER); if (n && max_linkhdr + hlen + tlen > MHLEN) { MCLGET(n, M_DONTWAIT); if ((n->m_flags & M_EXT) == 0) { m_freem(n); n = NULL; } } if (!n) { m_freem(m); return ENOBUFS; } MCLAIM(n, &tcp_tx_mowner); n->m_data += max_linkhdr; n->m_len = hlen + tlen; m_copyback(n, 0, hlen, mtod(m, void *)); m_copyback(n, hlen, tlen, (void *)th0); m_freem(m); m = n; n = NULL; } #define xchg(a,b,type) { type t; t=a; a=b; b=t; } switch (family) { case AF_INET: ip = mtod(m, struct ip *); th = (struct tcphdr *)(ip + 1); ip->ip_p = IPPROTO_TCP; xchg(ip->ip_dst, ip->ip_src, struct in_addr); ip->ip_p = IPPROTO_TCP; break; #ifdef INET6 case AF_INET6: ip6 = mtod(m, struct ip6_hdr *); th = (struct tcphdr *)(ip6 + 1); ip6->ip6_nxt = IPPROTO_TCP; xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr); ip6->ip6_nxt = IPPROTO_TCP; break; #endif #if 0 default: /* noone will visit here */ m_freem(m); return EAFNOSUPPORT; #endif } xchg(th->th_dport, th->th_sport, u_int16_t); #undef xchg tlen = 0; /*be friendly with the following code*/ } th->th_seq = htonl(seq); th->th_ack = htonl(ack); th->th_x2 = 0; if ((flags & TH_SYN) == 0) { if (tp) win >>= tp->rcv_scale; if (win > TCP_MAXWIN) win = TCP_MAXWIN; th->th_win = htons((u_int16_t)win); th->th_off = sizeof (struct tcphdr) >> 2; tlen += sizeof(*th); } else tlen += th->th_off << 2; m->m_len = hlen + tlen; m->m_pkthdr.len = hlen + tlen; m->m_pkthdr.rcvif = (struct ifnet *) 0; th->th_flags = flags; th->th_urp = 0; switch (family) { #ifdef INET case AF_INET: { struct ipovly *ipov = (struct ipovly *)ip; bzero(ipov->ih_x1, sizeof ipov->ih_x1); ipov->ih_len = htons((u_int16_t)tlen); th->th_sum = 0; th->th_sum = in_cksum(m, hlen + tlen); ip->ip_len = htons(hlen + tlen); ip->ip_ttl = ip_defttl; break; } #endif #ifdef INET6 case AF_INET6: { th->th_sum = 0; th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(struct ip6_hdr), tlen); ip6->ip6_plen = htons(tlen); if (tp && tp->t_in6pcb) { struct ifnet *oifp; ro = (struct route *)&tp->t_in6pcb->in6p_route; oifp = ro->ro_rt ? ro->ro_rt->rt_ifp : NULL; ip6->ip6_hlim = in6_selecthlim(tp->t_in6pcb, oifp); } else ip6->ip6_hlim = ip6_defhlim; ip6->ip6_flow &= ~IPV6_FLOWINFO_MASK; if (ip6_auto_flowlabel) { ip6->ip6_flow |= (htonl(ip6_randomflowlabel()) & IPV6_FLOWLABEL_MASK); } break; } #endif } if (tp && tp->t_inpcb) so = tp->t_inpcb->inp_socket; #ifdef INET6 else if (tp && tp->t_in6pcb) so = tp->t_in6pcb->in6p_socket; #endif else so = NULL; if (tp != NULL && tp->t_inpcb != NULL) { ro = &tp->t_inpcb->inp_route; #ifdef DIAGNOSTIC if (family != AF_INET) panic("tcp_respond: address family mismatch"); if (!in_hosteq(ip->ip_dst, tp->t_inpcb->inp_faddr)) { panic("tcp_respond: ip_dst %x != inp_faddr %x", ntohl(ip->ip_dst.s_addr), ntohl(tp->t_inpcb->inp_faddr.s_addr)); } #endif } #ifdef INET6 else if (tp != NULL && tp->t_in6pcb != NULL) { ro = (struct route *)&tp->t_in6pcb->in6p_route; #ifdef DIAGNOSTIC if (family == AF_INET) { if (!IN6_IS_ADDR_V4MAPPED(&tp->t_in6pcb->in6p_faddr)) panic("tcp_respond: not mapped addr"); if (bcmp(&ip->ip_dst, &tp->t_in6pcb->in6p_faddr.s6_addr32[3], sizeof(ip->ip_dst)) != 0) { panic("tcp_respond: ip_dst != in6p_faddr"); } } else if (family == AF_INET6) { if (!IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &tp->t_in6pcb->in6p_faddr)) panic("tcp_respond: ip6_dst != in6p_faddr"); } else panic("tcp_respond: address family mismatch"); #endif } #endif else ro = NULL; switch (family) { #ifdef INET case AF_INET: error = ip_output(m, NULL, ro, (tp && tp->t_mtudisc ? IP_MTUDISC : 0), (struct ip_moptions *)0, so); break; #endif #ifdef INET6 case AF_INET6: error = ip6_output(m, NULL, ro, 0, NULL, so, NULL); break; #endif default: error = EAFNOSUPPORT; break; } return (error); } /* * Template TCPCB. Rather than zeroing a new TCPCB and initializing * a bunch of members individually, we maintain this template for the * static and mostly-static components of the TCPCB, and copy it into * the new TCPCB instead. */ static struct tcpcb tcpcb_template = { /* * If TCP_NTIMERS ever changes, we'll need to update this * initializer. */ .t_timer = { CALLOUT_INITIALIZER, CALLOUT_INITIALIZER, CALLOUT_INITIALIZER, CALLOUT_INITIALIZER, }, .t_delack_ch = CALLOUT_INITIALIZER, .t_srtt = TCPTV_SRTTBASE, .t_rttmin = TCPTV_MIN, .snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT, .snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT, .snd_numholes = 0, .t_partialacks = -1, .t_bytes_acked = 0, }; /* * Updates the TCPCB template whenever a parameter that would affect * the template is changed. */ void tcp_tcpcb_template(void) { struct tcpcb *tp = &tcpcb_template; int flags; tp->t_peermss = tcp_mssdflt; tp->t_ourmss = tcp_mssdflt; tp->t_segsz = tcp_mssdflt; flags = 0; if (tcp_do_rfc1323 && tcp_do_win_scale) flags |= TF_REQ_SCALE; if (tcp_do_rfc1323 && tcp_do_timestamps) flags |= TF_REQ_TSTMP; tp->t_flags = flags; /* * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no * rtt estimate. Set rttvar so that srtt + 2 * rttvar gives * reasonable initial retransmit time. */ tp->t_rttvar = tcp_rttdflt * PR_SLOWHZ << (TCP_RTTVAR_SHIFT + 2 - 1); TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), TCPTV_MIN, TCPTV_REXMTMAX); } /* * Create a new TCP control block, making an * empty reassembly queue and hooking it to the argument * protocol control block. */ /* family selects inpcb, or in6pcb */ struct tcpcb * tcp_newtcpcb(int family, void *aux) { struct tcpcb *tp; int i; /* XXX Consider using a pool_cache for speed. */ tp = pool_get(&tcpcb_pool, PR_NOWAIT); /* splsoftnet via tcp_usrreq */ if (tp == NULL) return (NULL); memcpy(tp, &tcpcb_template, sizeof(*tp)); TAILQ_INIT(&tp->segq); TAILQ_INIT(&tp->timeq); tp->t_family = family; /* may be overridden later on */ TAILQ_INIT(&tp->snd_holes); LIST_INIT(&tp->t_sc); /* XXX can template this */ /* Don't sweat this loop; hopefully the compiler will unroll it. */ for (i = 0; i < TCPT_NTIMERS; i++) TCP_TIMER_INIT(tp, i); switch (family) { case AF_INET: { struct inpcb *inp = (struct inpcb *)aux; inp->inp_ip.ip_ttl = ip_defttl; inp->inp_ppcb = (void *)tp; tp->t_inpcb = inp; tp->t_mtudisc = ip_mtudisc; break; } #ifdef INET6 case AF_INET6: { struct in6pcb *in6p = (struct in6pcb *)aux; in6p->in6p_ip6.ip6_hlim = in6_selecthlim(in6p, in6p->in6p_route.ro_rt ? in6p->in6p_route.ro_rt->rt_ifp : NULL); in6p->in6p_ppcb = (void *)tp; tp->t_in6pcb = in6p; /* for IPv6, always try to run path MTU discovery */ tp->t_mtudisc = 1; break; } #endif /* INET6 */ default: pool_put(&tcpcb_pool, tp); /* splsoftnet via tcp_usrreq */ return (NULL); } /* * Initialize our timebase. When we send timestamps, we take * the delta from tcp_now -- this means each connection always * gets a timebase of 0, which makes it, among other things, * more difficult to determine how long a system has been up, * and thus how many TCP sequence increments have occurred. */ tp->ts_timebase = tcp_now; tp->t_congctl = tcp_congctl_global; tp->t_congctl->refcnt++; return (tp); } /* * Drop a TCP connection, reporting * the specified error. If connection is synchronized, * then send a RST to peer. */ struct tcpcb * tcp_drop(struct tcpcb *tp, int errno) { struct socket *so = NULL; #ifdef DIAGNOSTIC if (tp->t_inpcb && tp->t_in6pcb) panic("tcp_drop: both t_inpcb and t_in6pcb are set"); #endif #ifdef INET if (tp->t_inpcb) so = tp->t_inpcb->inp_socket; #endif #ifdef INET6 if (tp->t_in6pcb) so = tp->t_in6pcb->in6p_socket; #endif if (!so) return NULL; if (TCPS_HAVERCVDSYN(tp->t_state)) { tp->t_state = TCPS_CLOSED; (void) tcp_output(tp); tcpstat.tcps_drops++; } else tcpstat.tcps_conndrops++; if (errno == ETIMEDOUT && tp->t_softerror) errno = tp->t_softerror; so->so_error = errno; return (tcp_close(tp)); } /* * Return whether this tcpcb is marked as dead, indicating * to the calling timer function that no further action should * be taken, as we are about to release this tcpcb. The release * of the storage will be done if this is the last timer running. * * This should be called from the callout handler function after * callout_ack() is done, so that the number of invoking timer * functions is 0. */ int tcp_isdead(struct tcpcb *tp) { int dead = (tp->t_flags & TF_DEAD); if (__predict_false(dead)) { if (tcp_timers_invoking(tp) > 0) /* not quite there yet -- count separately? */ return dead; tcpstat.tcps_delayed_free++; pool_put(&tcpcb_pool, tp); /* splsoftnet via tcp_timer.c */ } return dead; } /* * Close a TCP control block: * discard all space held by the tcp * discard internet protocol block * wake up any sleepers */ struct tcpcb * tcp_close(struct tcpcb *tp) { struct inpcb *inp; #ifdef INET6 struct in6pcb *in6p; #endif struct socket *so; #ifdef RTV_RTT struct rtentry *rt; #endif struct route *ro; inp = tp->t_inpcb; #ifdef INET6 in6p = tp->t_in6pcb; #endif so = NULL; ro = NULL; if (inp) { so = inp->inp_socket; ro = &inp->inp_route; } #ifdef INET6 else if (in6p) { so = in6p->in6p_socket; ro = (struct route *)&in6p->in6p_route; } #endif #ifdef RTV_RTT /* * If we sent enough data to get some meaningful characteristics, * save them in the routing entry. 'Enough' is arbitrarily * defined as the sendpipesize (default 4K) * 16. This would * give us 16 rtt samples assuming we only get one sample per * window (the usual case on a long haul net). 16 samples is * enough for the srtt filter to converge to within 5% of the correct * value; fewer samples and we could save a very bogus rtt. * * Don't update the default route's characteristics and don't * update anything that the user "locked". */ if (SEQ_LT(tp->iss + so->so_snd.sb_hiwat * 16, tp->snd_max) && ro && (rt = ro->ro_rt) && !in_nullhost(satosin(rt_key(rt))->sin_addr)) { u_long i = 0; if ((rt->rt_rmx.rmx_locks & RTV_RTT) == 0) { i = tp->t_srtt * ((RTM_RTTUNIT / PR_SLOWHZ) >> (TCP_RTT_SHIFT + 2)); if (rt->rt_rmx.rmx_rtt && i) /* * filter this update to half the old & half * the new values, converting scale. * See route.h and tcp_var.h for a * description of the scaling constants. */ rt->rt_rmx.rmx_rtt = (rt->rt_rmx.rmx_rtt + i) / 2; else rt->rt_rmx.rmx_rtt = i; } if ((rt->rt_rmx.rmx_locks & RTV_RTTVAR) == 0) { i = tp->t_rttvar * ((RTM_RTTUNIT / PR_SLOWHZ) >> (TCP_RTTVAR_SHIFT + 2)); if (rt->rt_rmx.rmx_rttvar && i) rt->rt_rmx.rmx_rttvar = (rt->rt_rmx.rmx_rttvar + i) / 2; else rt->rt_rmx.rmx_rttvar = i; } /* * update the pipelimit (ssthresh) if it has been updated * already or if a pipesize was specified & the threshhold * got below half the pipesize. I.e., wait for bad news * before we start updating, then update on both good * and bad news. */ if (((rt->rt_rmx.rmx_locks & RTV_SSTHRESH) == 0 && (i = tp->snd_ssthresh) && rt->rt_rmx.rmx_ssthresh) || i < (rt->rt_rmx.rmx_sendpipe / 2)) { /* * convert the limit from user data bytes to * packets then to packet data bytes. */ i = (i + tp->t_segsz / 2) / tp->t_segsz; if (i < 2) i = 2; i *= (u_long)(tp->t_segsz + sizeof (struct tcpiphdr)); if (rt->rt_rmx.rmx_ssthresh) rt->rt_rmx.rmx_ssthresh = (rt->rt_rmx.rmx_ssthresh + i) / 2; else rt->rt_rmx.rmx_ssthresh = i; } } #endif /* RTV_RTT */ /* free the reassembly queue, if any */ TCP_REASS_LOCK(tp); (void) tcp_freeq(tp); TCP_REASS_UNLOCK(tp); /* free the SACK holes list. */ tcp_free_sackholes(tp); tp->t_congctl->refcnt--; tcp_canceltimers(tp); TCP_CLEAR_DELACK(tp); syn_cache_cleanup(tp); if (tp->t_template) { m_free(tp->t_template); tp->t_template = NULL; } if (tcp_timers_invoking(tp)) tp->t_flags |= TF_DEAD; else pool_put(&tcpcb_pool, tp); if (inp) { inp->inp_ppcb = 0; soisdisconnected(so); in_pcbdetach(inp); } #ifdef INET6 else if (in6p) { in6p->in6p_ppcb = 0; soisdisconnected(so); in6_pcbdetach(in6p); } #endif tcpstat.tcps_closed++; return ((struct tcpcb *)0); } int tcp_freeq(tp) struct tcpcb *tp; { struct ipqent *qe; int rv = 0; #ifdef TCPREASS_DEBUG int i = 0; #endif TCP_REASS_LOCK_CHECK(tp); while ((qe = TAILQ_FIRST(&tp->segq)) != NULL) { #ifdef TCPREASS_DEBUG printf("tcp_freeq[%p,%d]: %u:%u(%u) 0x%02x\n", tp, i++, qe->ipqe_seq, qe->ipqe_seq + qe->ipqe_len, qe->ipqe_len, qe->ipqe_flags & (TH_SYN|TH_FIN|TH_RST)); #endif TAILQ_REMOVE(&tp->segq, qe, ipqe_q); TAILQ_REMOVE(&tp->timeq, qe, ipqe_timeq); m_freem(qe->ipqe_m); tcpipqent_free(qe); rv = 1; } tp->t_segqlen = 0; KASSERT(TAILQ_EMPTY(&tp->timeq)); return (rv); } /* * Protocol drain routine. Called when memory is in short supply. */ void tcp_drain(void) { struct inpcb_hdr *inph; struct tcpcb *tp; /* * Free the sequence queue of all TCP connections. */ CIRCLEQ_FOREACH(inph, &tcbtable.inpt_queue, inph_queue) { switch (inph->inph_af) { case AF_INET: tp = intotcpcb((struct inpcb *)inph); break; #ifdef INET6 case AF_INET6: tp = in6totcpcb((struct in6pcb *)inph); break; #endif default: tp = NULL; break; } if (tp != NULL) { /* * We may be called from a device's interrupt * context. If the tcpcb is already busy, * just bail out now. */ if (tcp_reass_lock_try(tp) == 0) continue; if (tcp_freeq(tp)) tcpstat.tcps_connsdrained++; TCP_REASS_UNLOCK(tp); } } } /* * Notify a tcp user of an asynchronous error; * store error as soft error, but wake up user * (for now, won't do anything until can select for soft error). */ void tcp_notify(struct inpcb *inp, int error) { struct tcpcb *tp = (struct tcpcb *)inp->inp_ppcb; struct socket *so = inp->inp_socket; /* * Ignore some errors if we are hooked up. * If connection hasn't completed, has retransmitted several times, * and receives a second error, give up now. This is better * than waiting a long time to establish a connection that * can never complete. */ if (tp->t_state == TCPS_ESTABLISHED && (error == EHOSTUNREACH || error == ENETUNREACH || error == EHOSTDOWN)) { return; } else if (TCPS_HAVEESTABLISHED(tp->t_state) == 0 && tp->t_rxtshift > 3 && tp->t_softerror) so->so_error = error; else tp->t_softerror = error; wakeup((void *) &so->so_timeo); sorwakeup(so); sowwakeup(so); } #ifdef INET6 void tcp6_notify(struct in6pcb *in6p, int error) { struct tcpcb *tp = (struct tcpcb *)in6p->in6p_ppcb; struct socket *so = in6p->in6p_socket; /* * Ignore some errors if we are hooked up. * If connection hasn't completed, has retransmitted several times, * and receives a second error, give up now. This is better * than waiting a long time to establish a connection that * can never complete. */ if (tp->t_state == TCPS_ESTABLISHED && (error == EHOSTUNREACH || error == ENETUNREACH || error == EHOSTDOWN)) { return; } else if (TCPS_HAVEESTABLISHED(tp->t_state) == 0 && tp->t_rxtshift > 3 && tp->t_softerror) so->so_error = error; else tp->t_softerror = error; wakeup((void *) &so->so_timeo); sorwakeup(so); sowwakeup(so); } #endif #ifdef INET6 void tcp6_ctlinput(int cmd, const struct sockaddr *sa, void *d) { struct tcphdr th; void (*notify)(struct in6pcb *, int) = tcp6_notify; int nmatch; struct ip6_hdr *ip6; const struct sockaddr_in6 *sa6_src = NULL; const struct sockaddr_in6 *sa6 = (const struct sockaddr_in6 *)sa; struct mbuf *m; int off; if (sa->sa_family != AF_INET6 || sa->sa_len != sizeof(struct sockaddr_in6)) return; if ((unsigned)cmd >= PRC_NCMDS) return; else if (cmd == PRC_QUENCH) { /* * Don't honor ICMP Source Quench messages meant for * TCP connections. */ return; } else if (PRC_IS_REDIRECT(cmd)) notify = in6_rtchange, d = NULL; else if (cmd == PRC_MSGSIZE) ; /* special code is present, see below */ else if (cmd == PRC_HOSTDEAD) d = NULL; else if (inet6ctlerrmap[cmd] == 0) return; /* if the parameter is from icmp6, decode it. */ if (d != NULL) { struct ip6ctlparam *ip6cp = (struct ip6ctlparam *)d; m = ip6cp->ip6c_m; ip6 = ip6cp->ip6c_ip6; off = ip6cp->ip6c_off; sa6_src = ip6cp->ip6c_src; } else { m = NULL; ip6 = NULL; sa6_src = &sa6_any; off = 0; } if (ip6) { /* * XXX: We assume that when ip6 is non NULL, * M and OFF are valid. */ /* check if we can safely examine src and dst ports */ if (m->m_pkthdr.len < off + sizeof(th)) { if (cmd == PRC_MSGSIZE) icmp6_mtudisc_update((struct ip6ctlparam *)d, 0); return; } bzero(&th, sizeof(th)); m_copydata(m, off, sizeof(th), (void *)&th); if (cmd == PRC_MSGSIZE) { int valid = 0; /* * Check to see if we have a valid TCP connection * corresponding to the address in the ICMPv6 message * payload. */ if (in6_pcblookup_connect(&tcbtable, &sa6->sin6_addr, th.th_dport, (const struct in6_addr *)&sa6_src->sin6_addr, th.th_sport, 0)) valid++; /* * Depending on the value of "valid" and routing table * size (mtudisc_{hi,lo}wat), we will: * - recalcurate the new MTU and create the * corresponding routing entry, or * - ignore the MTU change notification. */ icmp6_mtudisc_update((struct ip6ctlparam *)d, valid); /* * no need to call in6_pcbnotify, it should have been * called via callback if necessary */ return; } nmatch = in6_pcbnotify(&tcbtable, sa, th.th_dport, (const struct sockaddr *)sa6_src, th.th_sport, cmd, NULL, notify); if (nmatch == 0 && syn_cache_count && (inet6ctlerrmap[cmd] == EHOSTUNREACH || inet6ctlerrmap[cmd] == ENETUNREACH || inet6ctlerrmap[cmd] == EHOSTDOWN)) syn_cache_unreach((const struct sockaddr *)sa6_src, sa, &th); } else { (void) in6_pcbnotify(&tcbtable, sa, 0, (const struct sockaddr *)sa6_src, 0, cmd, NULL, notify); } } #endif #ifdef INET /* assumes that ip header and tcp header are contiguous on mbuf */ void * tcp_ctlinput(int cmd, const struct sockaddr *sa, void *v) { struct ip *ip = v; struct tcphdr *th; struct icmp *icp; extern const int inetctlerrmap[]; void (*notify)(struct inpcb *, int) = tcp_notify; int errno; int nmatch; struct tcpcb *tp; u_int mtu; tcp_seq seq; struct inpcb *inp; #ifdef INET6 struct in6pcb *in6p; struct in6_addr src6, dst6; #endif if (sa->sa_family != AF_INET || sa->sa_len != sizeof(struct sockaddr_in)) return NULL; if ((unsigned)cmd >= PRC_NCMDS) return NULL; errno = inetctlerrmap[cmd]; if (cmd == PRC_QUENCH) /* * Don't honor ICMP Source Quench messages meant for * TCP connections. */ return NULL; else if (PRC_IS_REDIRECT(cmd)) notify = in_rtchange, ip = 0; else if (cmd == PRC_MSGSIZE && ip && ip->ip_v == 4) { /* * Check to see if we have a valid TCP connection * corresponding to the address in the ICMP message * payload. * * Boundary check is made in icmp_input(), with ICMP_ADVLENMIN. */ th = (struct tcphdr *)((char *)ip + (ip->ip_hl << 2)); #ifdef INET6 memset(&src6, 0, sizeof(src6)); memset(&dst6, 0, sizeof(dst6)); src6.s6_addr16[5] = dst6.s6_addr16[5] = 0xffff; memcpy(&src6.s6_addr32[3], &ip->ip_src, sizeof(struct in_addr)); memcpy(&dst6.s6_addr32[3], &ip->ip_dst, sizeof(struct in_addr)); #endif if ((inp = in_pcblookup_connect(&tcbtable, ip->ip_dst, th->th_dport, ip->ip_src, th->th_sport)) != NULL) #ifdef INET6 in6p = NULL; #else ; #endif #ifdef INET6 else if ((in6p = in6_pcblookup_connect(&tcbtable, &dst6, th->th_dport, &src6, th->th_sport, 0)) != NULL) ; #endif else return NULL; /* * Now that we've validated that we are actually communicating * with the host indicated in the ICMP message, locate the * ICMP header, recalculate the new MTU, and create the * corresponding routing entry. */ icp = (struct icmp *)((char *)ip - offsetof(struct icmp, icmp_ip)); if (inp) { if ((tp = intotcpcb(inp)) == NULL) return NULL; } #ifdef INET6 else if (in6p) { if ((tp = in6totcpcb(in6p)) == NULL) return NULL; } #endif else return NULL; seq = ntohl(th->th_seq); if (SEQ_LT(seq, tp->snd_una) || SEQ_GT(seq, tp->snd_max)) return NULL; /* * If the ICMP message advertises a Next-Hop MTU * equal or larger than the maximum packet size we have * ever sent, drop the message. */ mtu = (u_int)ntohs(icp->icmp_nextmtu); if (mtu >= tp->t_pmtud_mtu_sent) return NULL; if (mtu >= tcp_hdrsz(tp) + tp->t_pmtud_mss_acked) { /* * Calculate new MTU, and create corresponding * route (traditional PMTUD). */ tp->t_flags &= ~TF_PMTUD_PEND; icmp_mtudisc(icp, ip->ip_dst); } else { /* * Record the information got in the ICMP * message; act on it later. * If we had already recorded an ICMP message, * replace the old one only if the new message * refers to an older TCP segment */ if (tp->t_flags & TF_PMTUD_PEND) { if (SEQ_LT(tp->t_pmtud_th_seq, seq)) return NULL; } else tp->t_flags |= TF_PMTUD_PEND; tp->t_pmtud_th_seq = seq; tp->t_pmtud_nextmtu = icp->icmp_nextmtu; tp->t_pmtud_ip_len = icp->icmp_ip.ip_len; tp->t_pmtud_ip_hl = icp->icmp_ip.ip_hl; } return NULL; } else if (cmd == PRC_HOSTDEAD) ip = 0; else if (errno == 0) return NULL; if (ip && ip->ip_v == 4 && sa->sa_family == AF_INET) { th = (struct tcphdr *)((char *)ip + (ip->ip_hl << 2)); nmatch = in_pcbnotify(&tcbtable, satocsin(sa)->sin_addr, th->th_dport, ip->ip_src, th->th_sport, errno, notify); if (nmatch == 0 && syn_cache_count && (inetctlerrmap[cmd] == EHOSTUNREACH || inetctlerrmap[cmd] == ENETUNREACH || inetctlerrmap[cmd] == EHOSTDOWN)) { struct sockaddr_in sin; bzero(&sin, sizeof(sin)); sin.sin_len = sizeof(sin); sin.sin_family = AF_INET; sin.sin_port = th->th_sport; sin.sin_addr = ip->ip_src; syn_cache_unreach((struct sockaddr *)&sin, sa, th); } /* XXX mapped address case */ } else in_pcbnotifyall(&tcbtable, satocsin(sa)->sin_addr, errno, notify); return NULL; } /* * When a source quench is received, we are being notified of congestion. * Close the congestion window down to the Loss Window (one segment). * We will gradually open it again as we proceed. */ void tcp_quench(struct inpcb *inp, int errno) { struct tcpcb *tp = intotcpcb(inp); if (tp) { tp->snd_cwnd = tp->t_segsz; tp->t_bytes_acked = 0; } } #endif #ifdef INET6 void tcp6_quench(struct in6pcb *in6p, int errno) { struct tcpcb *tp = in6totcpcb(in6p); if (tp) { tp->snd_cwnd = tp->t_segsz; tp->t_bytes_acked = 0; } } #endif #ifdef INET /* * Path MTU Discovery handlers. */ void tcp_mtudisc_callback(struct in_addr faddr) { #ifdef INET6 struct in6_addr in6; #endif in_pcbnotifyall(&tcbtable, faddr, EMSGSIZE, tcp_mtudisc); #ifdef INET6 memset(&in6, 0, sizeof(in6)); in6.s6_addr16[5] = 0xffff; memcpy(&in6.s6_addr32[3], &faddr, sizeof(struct in_addr)); tcp6_mtudisc_callback(&in6); #endif } /* * On receipt of path MTU corrections, flush old route and replace it * with the new one. Retransmit all unacknowledged packets, to ensure * that all packets will be received. */ void tcp_mtudisc(struct inpcb *inp, int errno) { struct tcpcb *tp = intotcpcb(inp); struct rtentry *rt = in_pcbrtentry(inp); if (tp != 0) { if (rt != 0) { /* * If this was not a host route, remove and realloc. */ if ((rt->rt_flags & RTF_HOST) == 0) { in_rtchange(inp, errno); if ((rt = in_pcbrtentry(inp)) == 0) return; } /* * Slow start out of the error condition. We * use the MTU because we know it's smaller * than the previously transmitted segment. * * Note: This is more conservative than the * suggestion in draft-floyd-incr-init-win-03. */ if (rt->rt_rmx.rmx_mtu != 0) tp->snd_cwnd = TCP_INITIAL_WINDOW(tcp_init_win, rt->rt_rmx.rmx_mtu); } /* * Resend unacknowledged packets. */ tp->snd_nxt = tp->snd_una; tcp_output(tp); } } #endif #ifdef INET6 /* * Path MTU Discovery handlers. */ void tcp6_mtudisc_callback(struct in6_addr *faddr) { struct sockaddr_in6 sin6; bzero(&sin6, sizeof(sin6)); sin6.sin6_family = AF_INET6; sin6.sin6_len = sizeof(struct sockaddr_in6); sin6.sin6_addr = *faddr; (void) in6_pcbnotify(&tcbtable, (struct sockaddr *)&sin6, 0, (const struct sockaddr *)&sa6_any, 0, PRC_MSGSIZE, NULL, tcp6_mtudisc); } void tcp6_mtudisc(struct in6pcb *in6p, int errno) { struct tcpcb *tp = in6totcpcb(in6p); struct rtentry *rt = in6_pcbrtentry(in6p); if (tp != 0) { if (rt != 0) { /* * If this was not a host route, remove and realloc. */ if ((rt->rt_flags & RTF_HOST) == 0) { in6_rtchange(in6p, errno); if ((rt = in6_pcbrtentry(in6p)) == 0) return; } /* * Slow start out of the error condition. We * use the MTU because we know it's smaller * than the previously transmitted segment. * * Note: This is more conservative than the * suggestion in draft-floyd-incr-init-win-03. */ if (rt->rt_rmx.rmx_mtu != 0) tp->snd_cwnd = TCP_INITIAL_WINDOW(tcp_init_win, rt->rt_rmx.rmx_mtu); } /* * Resend unacknowledged packets. */ tp->snd_nxt = tp->snd_una; tcp_output(tp); } } #endif /* INET6 */ /* * Compute the MSS to advertise to the peer. Called only during * the 3-way handshake. If we are the server (peer initiated * connection), we are called with a pointer to the interface * on which the SYN packet arrived. If we are the client (we * initiated connection), we are called with a pointer to the * interface out which this connection should go. * * NOTE: Do not subtract IP option/extension header size nor IPsec * header size from MSS advertisement. MSS option must hold the maximum * segment size we can accept, so it must always be: * max(if mtu) - ip header - tcp header */ u_long tcp_mss_to_advertise(const struct ifnet *ifp, int af) { extern u_long in_maxmtu; u_long mss = 0; u_long hdrsiz; /* * In order to avoid defeating path MTU discovery on the peer, * we advertise the max MTU of all attached networks as our MSS, * per RFC 1191, section 3.1. * * We provide the option to advertise just the MTU of * the interface on which we hope this connection will * be receiving. If we are responding to a SYN, we * will have a pretty good idea about this, but when * initiating a connection there is a bit more doubt. * * We also need to ensure that loopback has a large enough * MSS, as the loopback MTU is never included in in_maxmtu. */ if (ifp != NULL) switch (af) { case AF_INET: mss = ifp->if_mtu; break; #ifdef INET6 case AF_INET6: mss = IN6_LINKMTU(ifp); break; #endif } if (tcp_mss_ifmtu == 0) switch (af) { case AF_INET: mss = max(in_maxmtu, mss); break; #ifdef INET6 case AF_INET6: mss = max(in6_maxmtu, mss); break; #endif } switch (af) { case AF_INET: hdrsiz = sizeof(struct ip); break; #ifdef INET6 case AF_INET6: hdrsiz = sizeof(struct ip6_hdr); break; #endif default: hdrsiz = 0; break; } hdrsiz += sizeof(struct tcphdr); if (mss > hdrsiz) mss -= hdrsiz; mss = max(tcp_mssdflt, mss); return (mss); } /* * Set connection variables based on the peer's advertised MSS. * We are passed the TCPCB for the actual connection. If we * are the server, we are called by the compressed state engine * when the 3-way handshake is complete. If we are the client, * we are called when we receive the SYN,ACK from the server. * * NOTE: Our advertised MSS value must be initialized in the TCPCB * before this routine is called! */ void tcp_mss_from_peer(struct tcpcb *tp, int offer) { struct socket *so; #if defined(RTV_SPIPE) || defined(RTV_SSTHRESH) struct rtentry *rt; #endif u_long bufsize; int mss; #ifdef DIAGNOSTIC if (tp->t_inpcb && tp->t_in6pcb) panic("tcp_mss_from_peer: both t_inpcb and t_in6pcb are set"); #endif so = NULL; rt = NULL; #ifdef INET if (tp->t_inpcb) { so = tp->t_inpcb->inp_socket; #if defined(RTV_SPIPE) || defined(RTV_SSTHRESH) rt = in_pcbrtentry(tp->t_inpcb); #endif } #endif #ifdef INET6 if (tp->t_in6pcb) { so = tp->t_in6pcb->in6p_socket; #if defined(RTV_SPIPE) || defined(RTV_SSTHRESH) rt = in6_pcbrtentry(tp->t_in6pcb); #endif } #endif /* * As per RFC1122, use the default MSS value, unless they * sent us an offer. Do not accept offers less than 256 bytes. */ mss = tcp_mssdflt; if (offer) mss = offer; mss = max(mss, 256); /* sanity */ tp->t_peermss = mss; mss -= tcp_optlen(tp); #ifdef INET if (tp->t_inpcb) mss -= ip_optlen(tp->t_inpcb); #endif #ifdef INET6 if (tp->t_in6pcb) mss -= ip6_optlen(tp->t_in6pcb); #endif /* * If there's a pipesize, change the socket buffer to that size. * Make the socket buffer an integral number of MSS units. If * the MSS is larger than the socket buffer, artificially decrease * the MSS. */ #ifdef RTV_SPIPE if (rt != NULL && rt->rt_rmx.rmx_sendpipe != 0) bufsize = rt->rt_rmx.rmx_sendpipe; else #endif { KASSERT(so != NULL); bufsize = so->so_snd.sb_hiwat; } if (bufsize < mss) mss = bufsize; else { bufsize = roundup(bufsize, mss); if (bufsize > sb_max) bufsize = sb_max; (void) sbreserve(&so->so_snd, bufsize, so); } tp->t_segsz = mss; #ifdef RTV_SSTHRESH if (rt != NULL && rt->rt_rmx.rmx_ssthresh) { /* * There's some sort of gateway or interface buffer * limit on the path. Use this to set the slow * start threshold, but set the threshold to no less * than 2 * MSS. */ tp->snd_ssthresh = max(2 * mss, rt->rt_rmx.rmx_ssthresh); } #endif } /* * Processing necessary when a TCP connection is established. */ void tcp_established(struct tcpcb *tp) { struct socket *so; #ifdef RTV_RPIPE struct rtentry *rt; #endif u_long bufsize; #ifdef DIAGNOSTIC if (tp->t_inpcb && tp->t_in6pcb) panic("tcp_established: both t_inpcb and t_in6pcb are set"); #endif so = NULL; rt = NULL; #ifdef INET if (tp->t_inpcb) { so = tp->t_inpcb->inp_socket; #if defined(RTV_RPIPE) rt = in_pcbrtentry(tp->t_inpcb); #endif } #endif #ifdef INET6 if (tp->t_in6pcb) { so = tp->t_in6pcb->in6p_socket; #if defined(RTV_RPIPE) rt = in6_pcbrtentry(tp->t_in6pcb); #endif } #endif tp->t_state = TCPS_ESTABLISHED; TCP_TIMER_ARM(tp, TCPT_KEEP, tcp_keepidle); #ifdef RTV_RPIPE if (rt != NULL && rt->rt_rmx.rmx_recvpipe != 0) bufsize = rt->rt_rmx.rmx_recvpipe; else #endif { KASSERT(so != NULL); bufsize = so->so_rcv.sb_hiwat; } if (bufsize > tp->t_ourmss) { bufsize = roundup(bufsize, tp->t_ourmss); if (bufsize > sb_max) bufsize = sb_max; (void) sbreserve(&so->so_rcv, bufsize, so); } } /* * Check if there's an initial rtt or rttvar. Convert from the * route-table units to scaled multiples of the slow timeout timer. * Called only during the 3-way handshake. */ void tcp_rmx_rtt(struct tcpcb *tp) { #ifdef RTV_RTT struct rtentry *rt = NULL; int rtt; #ifdef DIAGNOSTIC if (tp->t_inpcb && tp->t_in6pcb) panic("tcp_rmx_rtt: both t_inpcb and t_in6pcb are set"); #endif #ifdef INET if (tp->t_inpcb) rt = in_pcbrtentry(tp->t_inpcb); #endif #ifdef INET6 if (tp->t_in6pcb) rt = in6_pcbrtentry(tp->t_in6pcb); #endif if (rt == NULL) return; if (tp->t_srtt == 0 && (rtt = rt->rt_rmx.rmx_rtt)) { /* * XXX The lock bit for MTU indicates that the value * is also a minimum value; this is subject to time. */ if (rt->rt_rmx.rmx_locks & RTV_RTT) TCPT_RANGESET(tp->t_rttmin, rtt / (RTM_RTTUNIT / PR_SLOWHZ), TCPTV_MIN, TCPTV_REXMTMAX); tp->t_srtt = rtt / ((RTM_RTTUNIT / PR_SLOWHZ) >> (TCP_RTT_SHIFT + 2)); if (rt->rt_rmx.rmx_rttvar) { tp->t_rttvar = rt->rt_rmx.rmx_rttvar / ((RTM_RTTUNIT / PR_SLOWHZ) >> (TCP_RTTVAR_SHIFT + 2)); } else { /* Default variation is +- 1 rtt */ tp->t_rttvar = tp->t_srtt >> (TCP_RTT_SHIFT - TCP_RTTVAR_SHIFT); } TCPT_RANGESET(tp->t_rxtcur, ((tp->t_srtt >> 2) + tp->t_rttvar) >> (1 + 2), tp->t_rttmin, TCPTV_REXMTMAX); } #endif } tcp_seq tcp_iss_seq = 0; /* tcp initial seq # */ #if NRND > 0 u_int8_t tcp_iss_secret[16]; /* 128 bits; should be plenty */ #endif /* * Get a new sequence value given a tcp control block */ tcp_seq tcp_new_iss(struct tcpcb *tp, tcp_seq addin) { #ifdef INET if (tp->t_inpcb != NULL) { return (tcp_new_iss1(&tp->t_inpcb->inp_laddr, &tp->t_inpcb->inp_faddr, tp->t_inpcb->inp_lport, tp->t_inpcb->inp_fport, sizeof(tp->t_inpcb->inp_laddr), addin)); } #endif #ifdef INET6 if (tp->t_in6pcb != NULL) { return (tcp_new_iss1(&tp->t_in6pcb->in6p_laddr, &tp->t_in6pcb->in6p_faddr, tp->t_in6pcb->in6p_lport, tp->t_in6pcb->in6p_fport, sizeof(tp->t_in6pcb->in6p_laddr), addin)); } #endif /* Not possible. */ panic("tcp_new_iss"); } /* * This routine actually generates a new TCP initial sequence number. */ tcp_seq tcp_new_iss1(void *laddr, void *faddr, u_int16_t lport, u_int16_t fport, size_t addrsz, tcp_seq addin) { tcp_seq tcp_iss; #if NRND > 0 static int beenhere; /* * If we haven't been here before, initialize our cryptographic * hash secret. */ if (beenhere == 0) { rnd_extract_data(tcp_iss_secret, sizeof(tcp_iss_secret), RND_EXTRACT_ANY); beenhere = 1; } if (tcp_do_rfc1948) { MD5_CTX ctx; u_int8_t hash[16]; /* XXX MD5 knowledge */ /* * Compute the base value of the ISS. It is a hash * of (saddr, sport, daddr, dport, secret). */ MD5Init(&ctx); MD5Update(&ctx, (u_char *) laddr, addrsz); MD5Update(&ctx, (u_char *) &lport, sizeof(lport)); MD5Update(&ctx, (u_char *) faddr, addrsz); MD5Update(&ctx, (u_char *) &fport, sizeof(fport)); MD5Update(&ctx, tcp_iss_secret, sizeof(tcp_iss_secret)); MD5Final(hash, &ctx); memcpy(&tcp_iss, hash, sizeof(tcp_iss)); /* * Now increment our "timer", and add it in to * the computed value. * * XXX Use `addin'? * XXX TCP_ISSINCR too large to use? */ tcp_iss_seq += TCP_ISSINCR; #ifdef TCPISS_DEBUG printf("ISS hash 0x%08x, ", tcp_iss); #endif tcp_iss += tcp_iss_seq + addin; #ifdef TCPISS_DEBUG printf("new ISS 0x%08x\n", tcp_iss); #endif } else #endif /* NRND > 0 */ { /* * Randomize. */ #if NRND > 0 rnd_extract_data(&tcp_iss, sizeof(tcp_iss), RND_EXTRACT_ANY); #else tcp_iss = arc4random(); #endif /* * If we were asked to add some amount to a known value, * we will take a random value obtained above, mask off * the upper bits, and add in the known value. We also * add in a constant to ensure that we are at least a * certain distance from the original value. * * This is used when an old connection is in timed wait * and we have a new one coming in, for instance. */ if (addin != 0) { #ifdef TCPISS_DEBUG printf("Random %08x, ", tcp_iss); #endif tcp_iss &= TCP_ISS_RANDOM_MASK; tcp_iss += addin + TCP_ISSINCR; #ifdef TCPISS_DEBUG printf("Old ISS %08x, ISS %08x\n", addin, tcp_iss); #endif } else { tcp_iss &= TCP_ISS_RANDOM_MASK; tcp_iss += tcp_iss_seq; tcp_iss_seq += TCP_ISSINCR; #ifdef TCPISS_DEBUG printf("ISS %08x\n", tcp_iss); #endif } } if (tcp_compat_42) { /* * Limit it to the positive range for really old TCP * implementations. * Just AND off the top bit instead of checking if * is set first - saves a branch 50% of the time. */ tcp_iss &= 0x7fffffff; /* XXX */ } return (tcp_iss); } #if defined(IPSEC) || defined(FAST_IPSEC) /* compute ESP/AH header size for TCP, including outer IP header. */ size_t ipsec4_hdrsiz_tcp(struct tcpcb *tp) { struct inpcb *inp; size_t hdrsiz; /* XXX mapped addr case (tp->t_in6pcb) */ if (!tp || !tp->t_template || !(inp = tp->t_inpcb)) return 0; switch (tp->t_family) { case AF_INET: /* XXX: should use currect direction. */ hdrsiz = ipsec4_hdrsiz(tp->t_template, IPSEC_DIR_OUTBOUND, inp); break; default: hdrsiz = 0; break; } return hdrsiz; } #ifdef INET6 size_t ipsec6_hdrsiz_tcp(struct tcpcb *tp) { struct in6pcb *in6p; size_t hdrsiz; if (!tp || !tp->t_template || !(in6p = tp->t_in6pcb)) return 0; switch (tp->t_family) { case AF_INET6: /* XXX: should use currect direction. */ hdrsiz = ipsec6_hdrsiz(tp->t_template, IPSEC_DIR_OUTBOUND, in6p); break; case AF_INET: /* mapped address case - tricky */ default: hdrsiz = 0; break; } return hdrsiz; } #endif #endif /*IPSEC*/ /* * Determine the length of the TCP options for this connection. * * XXX: What do we do for SACK, when we add that? Just reserve * all of the space? Otherwise we can't exactly be incrementing * cwnd by an amount that varies depending on the amount we last * had to SACK! */ u_int tcp_optlen(struct tcpcb *tp) { u_int optlen; optlen = 0; if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == (TF_REQ_TSTMP | TF_RCVD_TSTMP)) optlen += TCPOLEN_TSTAMP_APPA; #ifdef TCP_SIGNATURE if (tp->t_flags & TF_SIGNATURE) optlen += TCPOLEN_SIGNATURE + 2; #endif /* TCP_SIGNATURE */ return optlen; } u_int tcp_hdrsz(struct tcpcb *tp) { u_int hlen; switch (tp->t_family) { #ifdef INET6 case AF_INET6: hlen = sizeof(struct ip6_hdr); break; #endif case AF_INET: hlen = sizeof(struct ip); break; default: hlen = 0; break; } hlen += sizeof(struct tcphdr); if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP) hlen += TCPOLEN_TSTAMP_APPA; #ifdef TCP_SIGNATURE if (tp->t_flags & TF_SIGNATURE) hlen += TCPOLEN_SIGLEN; #endif return hlen; }