diff options
author | andre <andre@FreeBSD.org> | 2007-03-15 15:59:28 +0000 |
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committer | andre <andre@FreeBSD.org> | 2007-03-15 15:59:28 +0000 |
commit | da1f4962209103a9c4b8de8081614312a2c05864 (patch) | |
tree | 958c5cc9f9700b70c7ad5f201a98774762724e25 /sys/netinet/tcp_syncache.c | |
parent | e384ffc370ce3185a1575f148f487dbaad04de2c (diff) | |
download | FreeBSD-src-da1f4962209103a9c4b8de8081614312a2c05864.zip FreeBSD-src-da1f4962209103a9c4b8de8081614312a2c05864.tar.gz |
Consolidate insertion of TCP options into a segment from within tcp_output()
and syncache_respond() into its own generic function tcp_addoptions().
tcp_addoptions() is alignment agnostic and does optimal packing in all cases.
In struct tcpopt rename to_requested_s_scale to just to_wscale.
Add a comment with quote from RFC1323: "The Window field in a SYN (i.e.,
a <SYN> or <SYN,ACK>) segment itself is never scaled."
Reviewed by: silby, mohans, julian
Sponsored by: TCP/IP Optimization Fundraise 2005
Diffstat (limited to 'sys/netinet/tcp_syncache.c')
-rw-r--r-- | sys/netinet/tcp_syncache.c | 118 |
1 files changed, 43 insertions, 75 deletions
diff --git a/sys/netinet/tcp_syncache.c b/sys/netinet/tcp_syncache.c index 84d3c10..931383c 100644 --- a/sys/netinet/tcp_syncache.c +++ b/sys/netinet/tcp_syncache.c @@ -1020,12 +1020,15 @@ syncache_add(struct in_conninfo *inc, struct tcpopt *to, struct tcphdr *th, * with auto sizing. This allows us to scale the * receive buffer over a wide range while not losing * any efficiency or fine granularity. + * + * RFC1323: The Window field in a SYN (i.e., a <SYN> + * or <SYN,ACK>) segment itself is never scaled. */ while (wscale < TCP_MAX_WINSHIFT && (0x1 << wscale) < tcp_minmss) wscale++; sc->sc_requested_r_scale = wscale; - sc->sc_requested_s_scale = to->to_requested_s_scale; + sc->sc_requested_s_scale = to->to_wscale; sc->sc_flags |= SCF_WINSCALE; } } @@ -1097,8 +1100,8 @@ syncache_respond(struct syncache *sc, struct mbuf *m) struct ip *ip = NULL; struct tcphdr *th; int optlen, error; - u_int16_t tlen, hlen, mssopt; - u_int8_t *optp; + u_int16_t hlen, tlen, mssopt; + struct tcpopt to; #ifdef INET6 struct ip6_hdr *ip6 = NULL; #endif @@ -1108,33 +1111,16 @@ syncache_respond(struct syncache *sc, struct mbuf *m) (sc->sc_inc.inc_isipv6) ? sizeof(struct ip6_hdr) : #endif sizeof(struct ip); + tlen = hlen + sizeof(struct tcphdr); /* Determine MSS we advertize to other end of connection. */ mssopt = tcp_mssopt(&sc->sc_inc); if (sc->sc_peer_mss) mssopt = max( min(sc->sc_peer_mss, mssopt), tcp_minmss); - /* Compute the size of the TCP options. */ - if (sc->sc_flags & SCF_NOOPT) { - optlen = 0; - } else { - optlen = TCPOLEN_MAXSEG + - ((sc->sc_flags & SCF_WINSCALE) ? 4 : 0) + - ((sc->sc_flags & SCF_TIMESTAMP) ? TCPOLEN_TSTAMP_APPA : 0); -#ifdef TCP_SIGNATURE - if (sc->sc_flags & SCF_SIGNATURE) - optlen += TCPOLEN_SIGNATURE; -#endif - if (sc->sc_flags & SCF_SACK) - optlen += TCPOLEN_SACK_PERMITTED; - optlen = roundup2(optlen, 4); - } - tlen = hlen + sizeof(struct tcphdr) + optlen; - - /* - * XXX: Assume that the entire packet will fit in a header mbuf. - */ - KASSERT(max_linkhdr + tlen <= MHLEN, ("syncache: mbuf too small")); + /* XXX: Assume that the entire packet will fit in a header mbuf. */ + KASSERT(max_linkhdr + tlen + MAX_TCPOPTLEN <= MHLEN, + ("syncache: mbuf too small")); /* Create the IP+TCP header from scratch. */ if (m) @@ -1197,70 +1183,52 @@ syncache_respond(struct syncache *sc, struct mbuf *m) th->th_seq = htonl(sc->sc_iss); th->th_ack = htonl(sc->sc_irs + 1); - th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; + th->th_off = sizeof(struct tcphdr) >> 2; th->th_x2 = 0; th->th_flags = TH_SYN|TH_ACK; th->th_win = htons(sc->sc_wnd); th->th_urp = 0; /* Tack on the TCP options. */ - if (optlen != 0) { - optp = (u_int8_t *)(th + 1); - *optp++ = TCPOPT_MAXSEG; - *optp++ = TCPOLEN_MAXSEG; - *optp++ = (mssopt >> 8) & 0xff; - *optp++ = mssopt & 0xff; + if ((sc->sc_flags & SCF_NOOPT) == 0) { + to.to_flags = 0; + to.to_mss = mssopt; + to.to_flags = TOF_MSS; if (sc->sc_flags & SCF_WINSCALE) { - *((u_int32_t *)optp) = htonl(TCPOPT_NOP << 24 | - TCPOPT_WINDOW << 16 | TCPOLEN_WINDOW << 8 | - sc->sc_requested_r_scale); - optp += 4; + to.to_wscale = sc->sc_requested_r_scale; + to.to_flags |= TOF_SCALE; } - if (sc->sc_flags & SCF_TIMESTAMP) { - u_int32_t *lp = (u_int32_t *)(optp); - - /* Form timestamp option per appendix A of RFC 1323. */ - *lp++ = htonl(TCPOPT_TSTAMP_HDR); - if (sc->sc_ts) - *lp++ = htonl(sc->sc_ts); - else - *lp++ = htonl(ticks); - *lp = htonl(sc->sc_tsreflect); - optp += TCPOLEN_TSTAMP_APPA; + /* Virgin timestamp or TCP cookie enhanced one. */ + to.to_tsval = sc->sc_ts ? sc->sc_ts : ticks; + to.to_tsecr = sc->sc_tsreflect; + to.to_flags |= TOF_TS; } - + if (sc->sc_flags & SCF_SACK) + to.to_flags |= TOF_SACKPERM; #ifdef TCP_SIGNATURE - /* - * Handle TCP-MD5 passive opener response. - */ - if (sc->sc_flags & SCF_SIGNATURE) { - u_int8_t *bp = optp; - int i; - - *bp++ = TCPOPT_SIGNATURE; - *bp++ = TCPOLEN_SIGNATURE; - for (i = 0; i < TCP_SIGLEN; i++) - *bp++ = 0; - tcp_signature_compute(m, sizeof(struct ip), 0, optlen, - optp + 2, IPSEC_DIR_OUTBOUND); - optp += TCPOLEN_SIGNATURE; - } -#endif /* TCP_SIGNATURE */ + if (sc->sc_flags & SCF_SIGNATURE) + to.to_flags |= TOF_SIGNATURE; +#endif + optlen = tcp_addoptions(&to, (u_char *)(th + 1)); - if (sc->sc_flags & SCF_SACK) { - *optp++ = TCPOPT_SACK_PERMITTED; - *optp++ = TCPOLEN_SACK_PERMITTED; - } +#ifdef TCP_SIGNATURE + tcp_signature_compute(m, sizeof(struct ip), 0, optlen, + to.to_signature, IPSEC_DIR_OUTBOUND); +#endif - { - /* Pad TCP options to a 4 byte boundary */ - int padlen = optlen - (optp - (u_int8_t *)(th + 1)); - while (padlen-- > 0) - *optp++ = TCPOPT_EOL; - } - } + /* Adjust headers by option size. */ + th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; + m->m_len += optlen; + m->m_pkthdr.len += optlen; +#ifdef INET6 + if (sc->sc_inc.inc_isipv6) + ip6->ip6_plen = htons(ntohs(ip6->ip6_plen) + optlen); +#endif + ip->ip_len += optlen; + } else + optlen = 0; #ifdef INET6 if (sc->sc_inc.inc_isipv6) { @@ -1272,7 +1240,7 @@ syncache_respond(struct syncache *sc, struct mbuf *m) #endif { th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, - htons(tlen - hlen + IPPROTO_TCP)); + htons(tlen + optlen - hlen + IPPROTO_TCP)); m->m_pkthdr.csum_flags = CSUM_TCP; m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); error = ip_output(m, sc->sc_ipopts, NULL, 0, NULL, NULL); |