| /*- |
| * 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. |
| * 4. 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_output.c 8.4 (Berkeley) 5/24/95 |
| */ |
| |
| #include <sys/bsd_cdefs.h> |
| //__FBSDID("$FreeBSD$"); |
| |
| #include "bsd_opt_inet.h" |
| #include "bsd_opt_inet6.h" |
| #include "bsd_opt_ipsec.h" |
| #include "bsd_opt_tcpdebug.h" |
| |
| #include <sys/bsd_param.h> |
| #include <sys/bsd_systm.h> |
| #include <sys/bsd_domain.h> |
| #include <sys/bsd_kernel.h> |
| #include <sys/bsd_lock.h> |
| #include <sys/bsd_mbuf.h> |
| #include <sys/bsd_mutex.h> |
| #include <sys/bsd_protosw.h> |
| #include <sys/bsd_socket.h> |
| #include <sys/bsd_socketvar.h> |
| //baoyg//#include <sys/bsd_sysctl.h> |
| |
| #include <net/bsd_if.h> |
| #include <net/bsd_route.h> |
| #include <net/bsd_vnet.h> |
| |
| #include <netinet/bsd_in.h> |
| #include <netinet/bsd_in_systm.h> |
| #include <netinet/bsd_ip.h> |
| #include <netinet/bsd_in_pcb.h> |
| #include <netinet/bsd_ip_var.h> |
| #include <netinet/bsd_ip_options.h> |
| #ifdef INET6 |
| #include <netinet6/bsd_in6_pcb.h> |
| #include <netinet/bsd_ip6.h> |
| #include <netinet6/bsd_ip6_var.h> |
| #endif |
| #include <netinet/bsd_tcp.h> |
| #define TCPOUTFLAGS |
| #include <netinet/bsd_tcp_fsm.h> |
| #include <netinet/bsd_tcp_seq.h> |
| #include <netinet/bsd_tcp_timer.h> |
| #include <netinet/bsd_tcp_var.h> |
| #include <netinet/bsd_tcpip.h> |
| #ifdef TCPDEBUG |
| #include <netinet/bsd_tcp_debug.h> |
| #endif |
| |
| #ifdef IPSEC |
| #include <netipsec/bsd_ipsec.h> |
| #endif /*IPSEC*/ |
| |
| #include <machine/bsd_in_cksum.h> |
| |
| #ifdef MAC |
| #include <security/mac/bsd_mac_framework.h> |
| #endif |
| |
| #ifdef notyet |
| extern struct mbuf *m_copypack(); |
| #endif |
| |
| extern int bsd_hz; |
| extern int bsd_ticks; |
| |
| VNET_DEFINE(int, path_mtu_discovery); |
| VNET_DEFINE(int, ss_fltsz); |
| VNET_DEFINE(int, ss_fltsz_local); |
| VNET_DEFINE(int, tcp_do_newreno); |
| VNET_DEFINE(int, tcp_do_tso); |
| VNET_DEFINE(int, tcp_do_autosndbuf); |
| VNET_DEFINE(int, tcp_autosndbuf_inc); |
| VNET_DEFINE(int, tcp_autosndbuf_max); |
| /* |
| SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, path_mtu_discovery, CTLFLAG_RW, |
| &VNET_NAME(path_mtu_discovery), 1, |
| "Enable Path MTU Discovery"); |
| |
| SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, slowstart_flightsize, CTLFLAG_RW, |
| &VNET_NAME(ss_fltsz), 1, |
| "Slow start flight size"); |
| |
| SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, local_slowstart_flightsize, |
| CTLFLAG_RW, &VNET_NAME(ss_fltsz_local), 1, |
| "Slow start flight size for local networks"); |
| |
| SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, newreno, CTLFLAG_RW, |
| &VNET_NAME(tcp_do_newreno), 0, |
| "Enable NewReno Algorithms"); |
| |
| SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, tso, CTLFLAG_RW, |
| &VNET_NAME(tcp_do_tso), 0, |
| "Enable TCP Segmentation Offload"); |
| |
| SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, sendbuf_auto, CTLFLAG_RW, |
| &VNET_NAME(tcp_do_autosndbuf), 0, |
| "Enable automatic send buffer sizing"); |
| |
| SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, sendbuf_inc, CTLFLAG_RW, |
| &VNET_NAME(tcp_autosndbuf_inc), 0, |
| "Incrementor step size of automatic send buffer"); |
| |
| SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, sendbuf_max, CTLFLAG_RW, |
| &VNET_NAME(tcp_autosndbuf_max), 0, |
| "Max size of automatic send buffer"); |
| */ |
| |
| /* |
| * Tcp output routine: figure out what should be sent and send it. |
| */ |
| int |
| tcp_output(struct tcpcb *tp) |
| { |
| struct socket *so = tp->t_inpcb->inp_socket; |
| long len, recwin, sendwin; |
| int off, flags, error; |
| struct mbuf *m; |
| struct ip *ip = NULL; |
| struct ipovly *ipov = NULL; |
| struct tcphdr *th; |
| u_char opt[TCP_MAXOLEN]; |
| unsigned ipoptlen, optlen, hdrlen; |
| #ifdef IPSEC |
| unsigned ipsec_optlen = 0; |
| #endif |
| int idle, sendalot; |
| int sack_rxmit, sack_bytes_rxmt; |
| struct sackhole *p; |
| int tso = 0; |
| struct tcpopt to; |
| #if 0 |
| int maxburst = TCP_MAXBURST; |
| #endif |
| #ifdef INET6 |
| struct ip6_hdr *ip6 = NULL; |
| int isipv6; |
| |
| isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) != 0; |
| #endif |
| |
| INP_WLOCK_ASSERT(tp->t_inpcb); |
| |
| /* |
| * Determine length of data that should be transmitted, |
| * and flags that will be used. |
| * If there is some data or critical controls (SYN, RST) |
| * to send, then transmit; otherwise, investigate further. |
| */ |
| idle = (tp->t_flags & TF_LASTIDLE) || (tp->snd_max == tp->snd_una); |
| if (idle && bsd_ticks - tp->t_rcvtime >= tp->t_rxtcur) { |
| /* |
| * We have been idle for "a while" and no acks are |
| * expected to clock out any data we send -- |
| * slow start to get ack "clock" running again. |
| * |
| * Set the slow-start flight size depending on whether |
| * this is a local network or not. |
| */ |
| int ss = V_ss_fltsz; |
| #ifdef INET6 |
| if (isipv6) { |
| if (in6_localaddr(&tp->t_inpcb->in6p_faddr)) |
| ss = V_ss_fltsz_local; |
| } else |
| #endif /* INET6 */ |
| if (in_localaddr(tp->t_inpcb->inp_faddr)) |
| ss = V_ss_fltsz_local; |
| tp->snd_cwnd = tp->t_maxseg * ss; |
| } |
| tp->t_flags &= ~TF_LASTIDLE; |
| if (idle) { |
| if (tp->t_flags & TF_MORETOCOME) { |
| tp->t_flags |= TF_LASTIDLE; |
| idle = 0; |
| } |
| } |
| again: |
| /* |
| * If we've recently taken a timeout, snd_max will be greater than |
| * snd_nxt. There may be SACK information that allows us to avoid |
| * resending already delivered data. Adjust snd_nxt accordingly. |
| */ |
| if ((tp->t_flags & TF_SACK_PERMIT) && |
| SEQ_LT(tp->snd_nxt, tp->snd_max)) |
| tcp_sack_adjust(tp); |
| sendalot = 0; |
| off = tp->snd_nxt - tp->snd_una; |
| sendwin = min(tp->snd_wnd, tp->snd_cwnd); |
| sendwin = min(sendwin, tp->snd_bwnd); |
| |
| flags = tcp_outflags[tp->t_state]; |
| /* |
| * Send any SACK-generated retransmissions. If we're explicitly trying |
| * to send out new data (when sendalot is 1), bypass this function. |
| * If we retransmit in fast recovery mode, decrement snd_cwnd, since |
| * we're replacing a (future) new transmission with a retransmission |
| * now, and we previously incremented snd_cwnd in tcp_input(). |
| */ |
| /* |
| * Still in sack recovery , reset rxmit flag to zero. |
| */ |
| sack_rxmit = 0; |
| sack_bytes_rxmt = 0; |
| len = 0; |
| p = NULL; |
| if ((tp->t_flags & TF_SACK_PERMIT) && IN_FASTRECOVERY(tp) && |
| (p = tcp_sack_output(tp, &sack_bytes_rxmt))) { |
| long cwin; |
| |
| cwin = min(tp->snd_wnd, tp->snd_cwnd) - sack_bytes_rxmt; |
| if (cwin < 0) |
| cwin = 0; |
| /* Do not retransmit SACK segments beyond snd_recover */ |
| if (SEQ_GT(p->end, tp->snd_recover)) { |
| /* |
| * (At least) part of sack hole extends beyond |
| * snd_recover. Check to see if we can rexmit data |
| * for this hole. |
| */ |
| if (SEQ_GEQ(p->rxmit, tp->snd_recover)) { |
| /* |
| * Can't rexmit any more data for this hole. |
| * That data will be rexmitted in the next |
| * sack recovery episode, when snd_recover |
| * moves past p->rxmit. |
| */ |
| p = NULL; |
| goto after_sack_rexmit; |
| } else |
| /* Can rexmit part of the current hole */ |
| len = ((long)ulmin(cwin, |
| tp->snd_recover - p->rxmit)); |
| } else |
| len = ((long)ulmin(cwin, p->end - p->rxmit)); |
| off = p->rxmit - tp->snd_una; |
| KASSERT(off >= 0,("%s: sack block to the left of una : %d", |
| __func__, off)); |
| if (len > 0) { |
| sack_rxmit = 1; |
| sendalot = 1; |
| TCPSTAT_INC(tcps_sack_rexmits); |
| TCPSTAT_ADD(tcps_sack_rexmit_bytes, |
| min(len, tp->t_maxseg)); |
| } |
| } |
| after_sack_rexmit: |
| /* |
| * Get standard flags, and add SYN or FIN if requested by 'hidden' |
| * state flags. |
| */ |
| if (tp->t_flags & TF_NEEDFIN) |
| flags |= TH_FIN; |
| if (tp->t_flags & TF_NEEDSYN) |
| flags |= TH_SYN; |
| |
| SOCKBUF_LOCK(&so->so_snd); |
| /* |
| * If in persist timeout with window of 0, send 1 byte. |
| * Otherwise, if window is small but nonzero |
| * and timer expired, we will send what we can |
| * and go to transmit state. |
| */ |
| if (tp->t_flags & TF_FORCEDATA) { |
| if (sendwin == 0) { |
| /* |
| * If we still have some data to send, then |
| * clear the FIN bit. Usually this would |
| * happen below when it realizes that we |
| * aren't sending all the data. However, |
| * if we have exactly 1 byte of unsent data, |
| * then it won't clear the FIN bit below, |
| * and if we are in persist state, we wind |
| * up sending the packet without recording |
| * that we sent the FIN bit. |
| * |
| * We can't just blindly clear the FIN bit, |
| * because if we don't have any more data |
| * to send then the probe will be the FIN |
| * itself. |
| */ |
| if (off < so->so_snd.sb_cc) |
| flags &= ~TH_FIN; |
| sendwin = 1; |
| } else { |
| tcp_timer_activate(tp, TT_PERSIST, 0); |
| tp->t_rxtshift = 0; |
| } |
| } |
| |
| /* |
| * If snd_nxt == snd_max and we have transmitted a FIN, the |
| * offset will be > 0 even if so_snd.sb_cc is 0, resulting in |
| * a negative length. This can also occur when TCP opens up |
| * its congestion window while receiving additional duplicate |
| * acks after fast-retransmit because TCP will reset snd_nxt |
| * to snd_max after the fast-retransmit. |
| * |
| * In the normal retransmit-FIN-only case, however, snd_nxt will |
| * be set to snd_una, the offset will be 0, and the length may |
| * wind up 0. |
| * |
| * If sack_rxmit is true we are retransmitting from the scoreboard |
| * in which case len is already set. |
| */ |
| if (sack_rxmit == 0) { |
| if (sack_bytes_rxmt == 0) |
| len = ((long)ulmin(so->so_snd.sb_cc, sendwin) - off); |
| else { |
| long cwin; |
| |
| /* |
| * We are inside of a SACK recovery episode and are |
| * sending new data, having retransmitted all the |
| * data possible in the scoreboard. |
| */ |
| len = ((long)ulmin(so->so_snd.sb_cc, tp->snd_wnd) |
| - off); |
| /* |
| * Don't remove this (len > 0) check ! |
| * We explicitly check for len > 0 here (although it |
| * isn't really necessary), to work around a gcc |
| * optimization issue - to force gcc to compute |
| * len above. Without this check, the computation |
| * of len is bungled by the optimizer. |
| */ |
| if (len > 0) { |
| cwin = tp->snd_cwnd - |
| (tp->snd_nxt - tp->sack_newdata) - |
| sack_bytes_rxmt; |
| if (cwin < 0) |
| cwin = 0; |
| len = lmin(len, cwin); |
| } |
| } |
| } |
| |
| /* |
| * Lop off SYN bit if it has already been sent. However, if this |
| * is SYN-SENT state and if segment contains data and if we don't |
| * know that foreign host supports TAO, suppress sending segment. |
| */ |
| if ((flags & TH_SYN) && SEQ_GT(tp->snd_nxt, tp->snd_una)) { |
| if (tp->t_state != TCPS_SYN_RECEIVED) |
| flags &= ~TH_SYN; |
| off--, len++; |
| } |
| |
| /* |
| * Be careful not to send data and/or FIN on SYN segments. |
| * This measure is needed to prevent interoperability problems |
| * with not fully conformant TCP implementations. |
| */ |
| if ((flags & TH_SYN) && (tp->t_flags & TF_NOOPT)) { |
| len = 0; |
| flags &= ~TH_FIN; |
| } |
| |
| if (len < 0) { |
| /* |
| * If FIN has been sent but not acked, |
| * but we haven't been called to retransmit, |
| * len will be < 0. Otherwise, window shrank |
| * after we sent into it. If window shrank to 0, |
| * cancel pending retransmit, pull snd_nxt back |
| * to (closed) window, and set the persist timer |
| * if it isn't already going. If the window didn't |
| * close completely, just wait for an ACK. |
| */ |
| len = 0; |
| if (sendwin == 0) { |
| tcp_timer_activate(tp, TT_REXMT, 0); |
| tp->t_rxtshift = 0; |
| tp->snd_nxt = tp->snd_una; |
| if (!tcp_timer_active(tp, TT_PERSIST)) |
| tcp_setpersist(tp); |
| } |
| } |
| |
| /* len will be >= 0 after this point. */ |
| KASSERT(len >= 0, ("[%s:%d]: len < 0", __func__, __LINE__)); |
| |
| /* |
| * Automatic sizing of send socket buffer. Often the send buffer |
| * size is not optimally adjusted to the actual network conditions |
| * at hand (delay bandwidth product). Setting the buffer size too |
| * small limits throughput on links with high bandwidth and high |
| * delay (eg. trans-continental/oceanic links). Setting the |
| * buffer size too big consumes too much real kernel memory, |
| * especially with many connections on busy servers. |
| * |
| * The criteria to step up the send buffer one notch are: |
| * 1. receive window of remote host is larger than send buffer |
| * (with a fudge factor of 5/4th); |
| * 2. send buffer is filled to 7/8th with data (so we actually |
| * have data to make use of it); |
| * 3. send buffer fill has not hit maximal automatic size; |
| * 4. our send window (slow start and cogestion controlled) is |
| * larger than sent but unacknowledged data in send buffer. |
| * |
| * The remote host receive window scaling factor may limit the |
| * growing of the send buffer before it reaches its allowed |
| * maximum. |
| * |
| * It scales directly with slow start or congestion window |
| * and does at most one step per received ACK. This fast |
| * scaling has the drawback of growing the send buffer beyond |
| * what is strictly necessary to make full use of a given |
| * delay*bandwith product. However testing has shown this not |
| * to be much of an problem. At worst we are trading wasting |
| * of available bandwith (the non-use of it) for wasting some |
| * socket buffer memory. |
| * |
| * TODO: Shrink send buffer during idle periods together |
| * with congestion window. Requires another timer. Has to |
| * wait for upcoming tcp timer rewrite. |
| */ |
| if (V_tcp_do_autosndbuf && so->so_snd.sb_flags & SB_AUTOSIZE) { |
| if ((tp->snd_wnd / 4 * 5) >= so->so_snd.sb_hiwat && |
| so->so_snd.sb_cc >= (so->so_snd.sb_hiwat / 8 * 7) && |
| so->so_snd.sb_cc < V_tcp_autosndbuf_max && |
| sendwin >= (so->so_snd.sb_cc - (tp->snd_nxt - tp->snd_una))) { |
| if (!sbreserve_locked(&so->so_snd, |
| min(so->so_snd.sb_hiwat + V_tcp_autosndbuf_inc, |
| V_tcp_autosndbuf_max), so, NULL/*curthread*/)) |
| so->so_snd.sb_flags &= ~SB_AUTOSIZE; |
| } |
| } |
| |
| /* |
| * Truncate to the maximum segment length or enable TCP Segmentation |
| * Offloading (if supported by hardware) and ensure that FIN is removed |
| * if the length no longer contains the last data byte. |
| * |
| * TSO may only be used if we are in a pure bulk sending state. The |
| * presence of TCP-MD5, SACK retransmits, SACK advertizements and |
| * IP options prevent using TSO. With TSO the TCP header is the same |
| * (except for the sequence number) for all generated packets. This |
| * makes it impossible to transmit any options which vary per generated |
| * segment or packet. |
| * |
| * The length of TSO bursts is limited to TCP_MAXWIN. That limit and |
| * removal of FIN (if not already catched here) are handled later after |
| * the exact length of the TCP options are known. |
| */ |
| #ifdef IPSEC |
| /* |
| * Pre-calculate here as we save another lookup into the darknesses |
| * of IPsec that way and can actually decide if TSO is ok. |
| */ |
| ipsec_optlen = ipsec_hdrsiz_tcp(tp); |
| #endif |
| if (len > tp->t_maxseg) { |
| if ((tp->t_flags & TF_TSO) && V_tcp_do_tso && |
| ((tp->t_flags & TF_SIGNATURE) == 0) && |
| tp->rcv_numsacks == 0 && sack_rxmit == 0 && |
| tp->t_inpcb->inp_options == NULL && |
| tp->t_inpcb->in6p_options == NULL |
| #ifdef IPSEC |
| && ipsec_optlen == 0 |
| #endif |
| ) { |
| tso = 1; |
| } else { |
| len = tp->t_maxseg; |
| sendalot = 1; |
| tso = 0; |
| } |
| } |
| if (sack_rxmit) { |
| if (SEQ_LT(p->rxmit + len, tp->snd_una + so->so_snd.sb_cc)) |
| flags &= ~TH_FIN; |
| } else { |
| if (SEQ_LT(tp->snd_nxt + len, tp->snd_una + so->so_snd.sb_cc)) |
| flags &= ~TH_FIN; |
| } |
| |
| recwin = sbspace(&so->so_rcv); |
| |
| /* |
| * Sender silly window avoidance. We transmit under the following |
| * conditions when len is non-zero: |
| * |
| * - We have a full segment (or more with TSO) |
| * - This is the last buffer in a write()/send() and we are |
| * either idle or running NODELAY |
| * - we've timed out (e.g. persist timer) |
| * - we have more then 1/2 the maximum send window's worth of |
| * data (receiver may be limited the window size) |
| * - we need to retransmit |
| */ |
| if (len) { |
| if (len >= tp->t_maxseg) |
| goto send; |
| /* |
| * NOTE! on localhost connections an 'ack' from the remote |
| * end may occur synchronously with the output and cause |
| * us to flush a buffer queued with moretocome. XXX |
| * |
| * note: the len + off check is almost certainly unnecessary. |
| */ |
| if (!(tp->t_flags & TF_MORETOCOME) && /* normal case */ |
| (idle || (tp->t_flags & TF_NODELAY)) && |
| len + off >= so->so_snd.sb_cc && |
| (tp->t_flags & TF_NOPUSH) == 0) { |
| goto send; |
| } |
| if (tp->t_flags & TF_FORCEDATA) /* typ. timeout case */ |
| goto send; |
| if (len >= tp->max_sndwnd / 2 && tp->max_sndwnd > 0) |
| goto send; |
| if (SEQ_LT(tp->snd_nxt, tp->snd_max)) /* retransmit case */ |
| goto send; |
| if (sack_rxmit) |
| goto send; |
| } |
| |
| /* |
| * Compare available window to amount of window |
| * known to peer (as advertised window less |
| * next expected input). If the difference is at least two |
| * max size segments, or at least 50% of the maximum possible |
| * window, then want to send a window update to peer. |
| * Skip this if the connection is in T/TCP half-open state. |
| * Don't send pure window updates when the peer has closed |
| * the connection and won't ever send more data. |
| */ |
| if (recwin > 0 && !(tp->t_flags & TF_NEEDSYN) && |
| !TCPS_HAVERCVDFIN(tp->t_state)) { |
| /* |
| * "adv" is the amount we can increase the window, |
| * taking into account that we are limited by |
| * TCP_MAXWIN << tp->rcv_scale. |
| */ |
| long adv = min(recwin, (long)TCP_MAXWIN << tp->rcv_scale) - |
| (tp->rcv_adv - tp->rcv_nxt); |
| |
| if (adv >= (long) (2 * tp->t_maxseg)) |
| goto send; |
| if (2 * adv >= (long) so->so_rcv.sb_hiwat) |
| goto send; |
| } |
| |
| /* |
| * Send if we owe the peer an ACK, RST, SYN, or urgent data. ACKNOW |
| * is also a catch-all for the retransmit timer timeout case. |
| */ |
| if (tp->t_flags & TF_ACKNOW) |
| goto send; |
| if ((flags & TH_RST) || |
| ((flags & TH_SYN) && (tp->t_flags & TF_NEEDSYN) == 0)) |
| goto send; |
| if (SEQ_GT(tp->snd_up, tp->snd_una)) |
| goto send; |
| /* |
| * If our state indicates that FIN should be sent |
| * and we have not yet done so, then we need to send. |
| */ |
| if (flags & TH_FIN && |
| ((tp->t_flags & TF_SENTFIN) == 0 || tp->snd_nxt == tp->snd_una)) |
| goto send; |
| /* |
| * In SACK, it is possible for tcp_output to fail to send a segment |
| * after the retransmission timer has been turned off. Make sure |
| * that the retransmission timer is set. |
| */ |
| if ((tp->t_flags & TF_SACK_PERMIT) && |
| SEQ_GT(tp->snd_max, tp->snd_una) && |
| !tcp_timer_active(tp, TT_REXMT) && |
| !tcp_timer_active(tp, TT_PERSIST)) { |
| tcp_timer_activate(tp, TT_REXMT, tp->t_rxtcur); |
| goto just_return; |
| } |
| /* |
| * TCP window updates are not reliable, rather a polling protocol |
| * using ``persist'' packets is used to insure receipt of window |
| * updates. The three ``states'' for the output side are: |
| * idle not doing retransmits or persists |
| * persisting to move a small or zero window |
| * (re)transmitting and thereby not persisting |
| * |
| * tcp_timer_active(tp, TT_PERSIST) |
| * is true when we are in persist state. |
| * (tp->t_flags & TF_FORCEDATA) |
| * is set when we are called to send a persist packet. |
| * tcp_timer_active(tp, TT_REXMT) |
| * is set when we are retransmitting |
| * The output side is idle when both timers are zero. |
| * |
| * If send window is too small, there is data to transmit, and no |
| * retransmit or persist is pending, then go to persist state. |
| * If nothing happens soon, send when timer expires: |
| * if window is nonzero, transmit what we can, |
| * otherwise force out a byte. |
| */ |
| if (so->so_snd.sb_cc && !tcp_timer_active(tp, TT_REXMT) && |
| !tcp_timer_active(tp, TT_PERSIST)) { |
| tp->t_rxtshift = 0; |
| tcp_setpersist(tp); |
| } |
| |
| /* |
| * No reason to send a segment, just return. |
| */ |
| just_return: |
| SOCKBUF_UNLOCK(&so->so_snd); |
| return (0); |
| |
| send: |
| SOCKBUF_LOCK_ASSERT(&so->so_snd); |
| /* |
| * Before ESTABLISHED, force sending of initial options |
| * unless TCP set not to do any options. |
| * NOTE: we assume that the IP/TCP header plus TCP options |
| * always fit in a single mbuf, leaving room for a maximum |
| * link header, i.e. |
| * max_linkhdr + sizeof (struct tcpiphdr) + optlen <= MCLBYTES |
| */ |
| optlen = 0; |
| #ifdef INET6 |
| if (isipv6) |
| hdrlen = sizeof (struct ip6_hdr) + sizeof (struct tcphdr); |
| else |
| #endif |
| hdrlen = sizeof (struct tcpiphdr); |
| |
| /* |
| * Compute options for segment. |
| * We only have to care about SYN and established connection |
| * segments. Options for SYN-ACK segments are handled in TCP |
| * syncache. |
| */ |
| if ((tp->t_flags & TF_NOOPT) == 0) { |
| to.to_flags = 0; |
| /* Maximum segment size. */ |
| if (flags & TH_SYN) { |
| tp->snd_nxt = tp->iss; |
| to.to_mss = tcp_mssopt(&tp->t_inpcb->inp_inc); |
| to.to_flags |= TOF_MSS; |
| } |
| /* Window scaling. */ |
| if ((flags & TH_SYN) && (tp->t_flags & TF_REQ_SCALE)) { |
| to.to_wscale = tp->request_r_scale; |
| to.to_flags |= TOF_SCALE; |
| } |
| /* Timestamps. */ |
| if ((tp->t_flags & TF_RCVD_TSTMP) || |
| ((flags & TH_SYN) && (tp->t_flags & TF_REQ_TSTMP))) { |
| to.to_tsval = bsd_ticks + tp->ts_offset; |
| to.to_tsecr = tp->ts_recent; |
| to.to_flags |= TOF_TS; |
| /* Set receive buffer autosizing timestamp. */ |
| if (tp->rfbuf_ts == 0 && |
| (so->so_rcv.sb_flags & SB_AUTOSIZE)) |
| tp->rfbuf_ts = bsd_ticks; |
| } |
| /* Selective ACK's. */ |
| if (tp->t_flags & TF_SACK_PERMIT) { |
| if (flags & TH_SYN) |
| to.to_flags |= TOF_SACKPERM; |
| else if (TCPS_HAVEESTABLISHED(tp->t_state) && |
| (tp->t_flags & TF_SACK_PERMIT) && |
| tp->rcv_numsacks > 0) { |
| to.to_flags |= TOF_SACK; |
| to.to_nsacks = tp->rcv_numsacks; |
| to.to_sacks = (u_char *)tp->sackblks; |
| } |
| } |
| #ifdef TCP_SIGNATURE |
| /* TCP-MD5 (RFC2385). */ |
| if (tp->t_flags & TF_SIGNATURE) |
| to.to_flags |= TOF_SIGNATURE; |
| #endif /* TCP_SIGNATURE */ |
| |
| /* Processing the options. */ |
| hdrlen += optlen = tcp_addoptions(&to, opt); |
| } |
| |
| #ifdef INET6 |
| if (isipv6) |
| ipoptlen = ip6_optlen(tp->t_inpcb); |
| else |
| #endif |
| if (tp->t_inpcb->inp_options) |
| ipoptlen = tp->t_inpcb->inp_options->m_len - |
| offsetof(struct ipoption, ipopt_list); |
| else |
| ipoptlen = 0; |
| #ifdef IPSEC |
| ipoptlen += ipsec_optlen; |
| #endif |
| |
| /* |
| * Adjust data length if insertion of options will |
| * bump the packet length beyond the t_maxopd length. |
| * Clear the FIN bit because we cut off the tail of |
| * the segment. |
| * |
| * When doing TSO limit a burst to TCP_MAXWIN minus the |
| * IP, TCP and Options length to keep ip->ip_len from |
| * overflowing. Prevent the last segment from being |
| * fractional thus making them all equal sized and set |
| * the flag to continue sending. TSO is disabled when |
| * IP options or IPSEC are present. |
| */ |
| if (len + optlen + ipoptlen > tp->t_maxopd) { |
| flags &= ~TH_FIN; |
| if (tso) { |
| if (len > TCP_MAXWIN - hdrlen - optlen) { |
| len = TCP_MAXWIN - hdrlen - optlen; |
| len = len - (len % (tp->t_maxopd - optlen)); |
| sendalot = 1; |
| } else if (tp->t_flags & TF_NEEDFIN) |
| sendalot = 1; |
| } else { |
| len = tp->t_maxopd - optlen - ipoptlen; |
| sendalot = 1; |
| } |
| } |
| |
| /*#ifdef DIAGNOSTIC*/ |
| #ifdef INET6 |
| if (max_linkhdr + hdrlen > MCLBYTES) |
| #else |
| if (max_linkhdr + hdrlen > MHLEN) |
| #endif |
| panic("tcphdr too big"); |
| /*#endif*/ |
| |
| /* |
| * This KASSERT is here to catch edge cases at a well defined place. |
| * Before, those had triggered (random) panic conditions further down. |
| */ |
| KASSERT(len >= 0, ("[%s:%d]: len < 0", __func__, __LINE__)); |
| |
| /* |
| * Grab a header mbuf, attaching a copy of data to |
| * be transmitted, and initialize the header from |
| * the template for sends on this connection. |
| */ |
| if (len) { |
| struct mbuf *mb; |
| u_int moff; |
| |
| if ((tp->t_flags & TF_FORCEDATA) && len == 1) |
| TCPSTAT_INC(tcps_sndprobe); |
| else if (SEQ_LT(tp->snd_nxt, tp->snd_max) || sack_rxmit) { |
| TCPSTAT_INC(tcps_sndrexmitpack); |
| TCPSTAT_ADD(tcps_sndrexmitbyte, len); |
| } else { |
| TCPSTAT_INC(tcps_sndpack); |
| TCPSTAT_ADD(tcps_sndbyte, len); |
| } |
| #ifdef notyet |
| if ((m = m_copypack(so->so_snd.sb_mb, off, |
| (int)len, max_linkhdr + hdrlen)) == 0) { |
| SOCKBUF_UNLOCK(&so->so_snd); |
| error = ENOBUFS; |
| goto out; |
| } |
| /* |
| * m_copypack left space for our hdr; use it. |
| */ |
| m->m_len += hdrlen; |
| m->m_data -= hdrlen; |
| #else |
| MGETHDR(m, M_DONTWAIT, MT_DATA); |
| if (m == NULL) { |
| SOCKBUF_UNLOCK(&so->so_snd); |
| error = ENOBUFS; |
| goto out; |
| } |
| #ifdef INET6 |
| if (MHLEN < hdrlen + max_linkhdr) { |
| MCLGET(m, M_DONTWAIT); |
| if ((m->m_flags & M_EXT) == 0) { |
| SOCKBUF_UNLOCK(&so->so_snd); |
| m_freem(m); |
| error = ENOBUFS; |
| goto out; |
| } |
| } |
| #endif |
| m->m_data += max_linkhdr; |
| m->m_len = hdrlen; |
| |
| /* |
| * Start the m_copy functions from the closest mbuf |
| * to the offset in the socket buffer chain. |
| */ |
| mb = sbsndptr(&so->so_snd, off, len, &moff); |
| |
| if (len <= MHLEN - hdrlen - max_linkhdr) { |
| m_copydata(mb, moff, (int)len, |
| mtod(m, caddr_t) + hdrlen); |
| m->m_len += len; |
| } else { |
| #ifndef DEBUG_MBUF_MNEXT |
| m->m_next = m_copy(mb, moff, (int)len); |
| #else |
| struct mbuf* tmpm = m_copy(mb, moff, (int)len); |
| CHECK_ADD_LINKCNT(m, tmpm, NULL, "tcp_output"); |
| m->m_next = tmpm; |
| |
| #endif |
| |
| if (m->m_next == NULL) { |
| SOCKBUF_UNLOCK(&so->so_snd); |
| (void) m_free(m); |
| error = ENOBUFS; |
| goto out; |
| } |
| } |
| #endif |
| /* |
| * If we're sending everything we've got, set PUSH. |
| * (This will keep happy those implementations which only |
| * give data to the user when a buffer fills or |
| * a PUSH comes in.) |
| */ |
| if (off + len == so->so_snd.sb_cc) |
| flags |= TH_PUSH; |
| SOCKBUF_UNLOCK(&so->so_snd); |
| } else { |
| SOCKBUF_UNLOCK(&so->so_snd); |
| if (tp->t_flags & TF_ACKNOW) |
| TCPSTAT_INC(tcps_sndacks); |
| else if (flags & (TH_SYN|TH_FIN|TH_RST)) |
| TCPSTAT_INC(tcps_sndctrl); |
| else if (SEQ_GT(tp->snd_up, tp->snd_una)) |
| TCPSTAT_INC(tcps_sndurg); |
| else |
| TCPSTAT_INC(tcps_sndwinup); |
| |
| MGETHDR(m, M_DONTWAIT, MT_DATA); |
| if (m == NULL) { |
| error = ENOBUFS; |
| goto out; |
| } |
| #ifdef INET6 |
| if (isipv6 && (MHLEN < hdrlen + max_linkhdr) && |
| MHLEN >= hdrlen) { |
| MH_ALIGN(m, hdrlen); |
| } else |
| #endif |
| m->m_data += max_linkhdr; |
| m->m_len = hdrlen; |
| } |
| SOCKBUF_UNLOCK_ASSERT(&so->so_snd); |
| m->m_pkthdr.rcvif = (struct ifnet *)0; |
| #ifdef MAC |
| mac_inpcb_create_mbuf(tp->t_inpcb, m); |
| #endif |
| #ifdef INET6 |
| if (isipv6) { |
| ip6 = mtod(m, struct ip6_hdr *); |
| th = (struct tcphdr *)(ip6 + 1); |
| tcpip_fillheaders(tp->t_inpcb, ip6, th); |
| } else |
| #endif /* INET6 */ |
| { |
| ip = mtod(m, struct ip *); |
| ipov = (struct ipovly *)ip; |
| th = (struct tcphdr *)(ip + 1); |
| tcpip_fillheaders(tp->t_inpcb, ip, th); |
| } |
| |
| /* |
| * Fill in fields, remembering maximum advertised |
| * window for use in delaying messages about window sizes. |
| * If resending a FIN, be sure not to use a new sequence number. |
| */ |
| if (flags & TH_FIN && tp->t_flags & TF_SENTFIN && |
| tp->snd_nxt == tp->snd_max) |
| tp->snd_nxt--; |
| /* |
| * If we are starting a connection, send ECN setup |
| * SYN packet. If we are on a retransmit, we may |
| * resend those bits a number of times as per |
| * RFC 3168. |
| */ |
| if (tp->t_state == TCPS_SYN_SENT && V_tcp_do_ecn) { |
| if (tp->t_rxtshift >= 1) { |
| if (tp->t_rxtshift <= V_tcp_ecn_maxretries) |
| flags |= TH_ECE|TH_CWR; |
| } else |
| flags |= TH_ECE|TH_CWR; |
| } |
| |
| if (tp->t_state == TCPS_ESTABLISHED && |
| (tp->t_flags & TF_ECN_PERMIT)) { |
| /* |
| * If the peer has ECN, mark data packets with |
| * ECN capable transmission (ECT). |
| * Ignore pure ack packets, retransmissions and window probes. |
| */ |
| if (len > 0 && SEQ_GEQ(tp->snd_nxt, tp->snd_max) && |
| !((tp->t_flags & TF_FORCEDATA) && len == 1)) { |
| #ifdef INET6 |
| if (isipv6) |
| ip6->ip6_flow |= htonl(IPTOS_ECN_ECT0 << 20); |
| else |
| #endif |
| ip->ip_tos |= IPTOS_ECN_ECT0; |
| TCPSTAT_INC(tcps_ecn_ect0); |
| } |
| |
| /* |
| * Reply with proper ECN notifications. |
| */ |
| if (tp->t_flags & TF_ECN_SND_CWR) { |
| flags |= TH_CWR; |
| tp->t_flags &= ~TF_ECN_SND_CWR; |
| } |
| if (tp->t_flags & TF_ECN_SND_ECE) |
| flags |= TH_ECE; |
| } |
| |
| /* |
| * If we are doing retransmissions, then snd_nxt will |
| * not reflect the first unsent octet. For ACK only |
| * packets, we do not want the sequence number of the |
| * retransmitted packet, we want the sequence number |
| * of the next unsent octet. So, if there is no data |
| * (and no SYN or FIN), use snd_max instead of snd_nxt |
| * when filling in ti_seq. But if we are in persist |
| * state, snd_max might reflect one byte beyond the |
| * right edge of the window, so use snd_nxt in that |
| * case, since we know we aren't doing a retransmission. |
| * (retransmit and persist are mutually exclusive...) |
| */ |
| if (sack_rxmit == 0) { |
| if (len || (flags & (TH_SYN|TH_FIN)) || |
| tcp_timer_active(tp, TT_PERSIST)) |
| th->th_seq = htonl(tp->snd_nxt); |
| else |
| th->th_seq = htonl(tp->snd_max); |
| } else { |
| th->th_seq = htonl(p->rxmit); |
| p->rxmit += len; |
| tp->sackhint.sack_bytes_rexmit += len; |
| } |
| th->th_ack = htonl(tp->rcv_nxt); |
| if (optlen) { |
| bcopy(opt, th + 1, optlen); |
| th->th_off = (sizeof (struct tcphdr) + optlen) >> 2; |
| } |
| th->th_flags = flags; |
| /* |
| * Calculate receive window. Don't shrink window, |
| * but avoid silly window syndrome. |
| */ |
| if (recwin < (long)(so->so_rcv.sb_hiwat / 4) && |
| recwin < (long)tp->t_maxseg) |
| recwin = 0; |
| if (recwin < (long)(tp->rcv_adv - tp->rcv_nxt)) |
| recwin = (long)(tp->rcv_adv - tp->rcv_nxt); |
| if (recwin > (long)TCP_MAXWIN << tp->rcv_scale) |
| recwin = (long)TCP_MAXWIN << tp->rcv_scale; |
| |
| /* |
| * According to RFC1323 the window field in a SYN (i.e., a <SYN> |
| * or <SYN,ACK>) segment itself is never scaled. The <SYN,ACK> |
| * case is handled in syncache. |
| */ |
| if (flags & TH_SYN) |
| th->th_win = htons((u_short) |
| (min(sbspace(&so->so_rcv), TCP_MAXWIN))); |
| else |
| th->th_win = htons((u_short)(recwin >> tp->rcv_scale)); |
| |
| /* |
| * Adjust the RXWIN0SENT flag - indicate that we have advertised |
| * a 0 window. This may cause the remote transmitter to stall. This |
| * flag tells soreceive() to disable delayed acknowledgements when |
| * draining the buffer. This can occur if the receiver is attempting |
| * to read more data than can be buffered prior to transmitting on |
| * the connection. |
| */ |
| if (th->th_win == 0) |
| tp->t_flags |= TF_RXWIN0SENT; |
| else |
| tp->t_flags &= ~TF_RXWIN0SENT; |
| if (SEQ_GT(tp->snd_up, tp->snd_nxt)) { |
| th->th_urp = htons((u_short)(tp->snd_up - tp->snd_nxt)); |
| th->th_flags |= TH_URG; |
| } else |
| /* |
| * If no urgent pointer to send, then we pull |
| * the urgent pointer to the left edge of the send window |
| * so that it doesn't drift into the send window on sequence |
| * number wraparound. |
| */ |
| tp->snd_up = tp->snd_una; /* drag it along */ |
| |
| #ifdef TCP_SIGNATURE |
| if (tp->t_flags & TF_SIGNATURE) { |
| int sigoff = to.to_signature - opt; |
| tcp_signature_compute(m, 0, len, optlen, |
| (u_char *)(th + 1) + sigoff, IPSEC_DIR_OUTBOUND); |
| } |
| #endif |
| |
| /* |
| * Put TCP length in extended header, and then |
| * checksum extended header and data. |
| */ |
| m->m_pkthdr.len = hdrlen + len; /* in6_cksum() need this */ |
| #ifdef INET6 |
| if (isipv6) |
| /* |
| * ip6_plen is not need to be filled now, and will be filled |
| * in ip6_output. |
| */ |
| th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(struct ip6_hdr), |
| sizeof(struct tcphdr) + optlen + len); |
| else |
| #endif /* INET6 */ |
| { |
| m->m_pkthdr.csum_flags = CSUM_TCP; |
| m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); |
| th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, |
| htons(sizeof(struct tcphdr) + IPPROTO_TCP + len + optlen)); |
| |
| /* IP version must be set here for ipv4/ipv6 checking later */ |
| KASSERT(ip->ip_v == IPVERSION, |
| ("%s: IP version incorrect: %d", __func__, ip->ip_v)); |
| } |
| |
| /* |
| * Enable TSO and specify the size of the segments. |
| * The TCP pseudo header checksum is always provided. |
| * XXX: Fixme: This is currently not the case for IPv6. |
| */ |
| if (tso) { |
| m->m_pkthdr.csum_flags = CSUM_TSO; |
| m->m_pkthdr.tso_segsz = tp->t_maxopd - optlen; |
| } |
| |
| /* |
| * In transmit state, time the transmission and arrange for |
| * the retransmit. In persist state, just set snd_max. |
| */ |
| if ((tp->t_flags & TF_FORCEDATA) == 0 || |
| !tcp_timer_active(tp, TT_PERSIST)) { |
| tcp_seq startseq = tp->snd_nxt; |
| |
| /* |
| * Advance snd_nxt over sequence space of this segment. |
| */ |
| if (flags & (TH_SYN|TH_FIN)) { |
| if (flags & TH_SYN) |
| tp->snd_nxt++; |
| if (flags & TH_FIN) { |
| tp->snd_nxt++; |
| tp->t_flags |= TF_SENTFIN; |
| } |
| } |
| if (sack_rxmit) |
| goto timer; |
| tp->snd_nxt += len; |
| if (SEQ_GT(tp->snd_nxt, tp->snd_max)) { |
| tp->snd_max = tp->snd_nxt; |
| /* |
| * Time this transmission if not a retransmission and |
| * not currently timing anything. |
| */ |
| if (tp->t_rtttime == 0) { |
| tp->t_rtttime = bsd_ticks; |
| tp->t_rtseq = startseq; |
| TCPSTAT_INC(tcps_segstimed); |
| } |
| } |
| |
| /* |
| * Set retransmit timer if not currently set, |
| * and not doing a pure ack or a keep-alive probe. |
| * Initial value for retransmit timer is smoothed |
| * round-trip time + 2 * round-trip time variance. |
| * Initialize shift counter which is used for backoff |
| * of retransmit time. |
| */ |
| timer: |
| if (!tcp_timer_active(tp, TT_REXMT) && |
| ((sack_rxmit && tp->snd_nxt != tp->snd_max) || |
| (tp->snd_nxt != tp->snd_una))) { |
| if (tcp_timer_active(tp, TT_PERSIST)) { |
| tcp_timer_activate(tp, TT_PERSIST, 0); |
| tp->t_rxtshift = 0; |
| } |
| tcp_timer_activate(tp, TT_REXMT, tp->t_rxtcur); |
| } |
| } else { |
| /* |
| * Persist case, update snd_max but since we are in |
| * persist mode (no window) we do not update snd_nxt. |
| */ |
| int xlen = len; |
| if (flags & TH_SYN) |
| ++xlen; |
| if (flags & TH_FIN) { |
| ++xlen; |
| tp->t_flags |= TF_SENTFIN; |
| } |
| if (SEQ_GT(tp->snd_nxt + xlen, tp->snd_max)) |
| tp->snd_max = tp->snd_nxt + len; |
| } |
| |
| #ifdef TCPDEBUG |
| /* |
| * Trace. |
| */ |
| if (so->so_options & SO_DEBUG) { |
| u_short save = 0; |
| #ifdef INET6 |
| if (!isipv6) |
| #endif |
| { |
| save = ipov->ih_len; |
| ipov->ih_len = htons(m->m_pkthdr.len /* - hdrlen + (th->th_off << 2) */); |
| } |
| tcp_trace(TA_OUTPUT, tp->t_state, tp, mtod(m, void *), th, 0); |
| #ifdef INET6 |
| if (!isipv6) |
| #endif |
| ipov->ih_len = save; |
| } |
| #endif |
| |
| /* |
| * Fill in IP length and desired time to live and |
| * send to IP level. There should be a better way |
| * to handle ttl and tos; we could keep them in |
| * the template, but need a way to checksum without them. |
| */ |
| /* |
| * m->m_pkthdr.len should have been set before cksum calcuration, |
| * because in6_cksum() need it. |
| */ |
| #ifdef INET6 |
| if (isipv6) { |
| /* |
| * we separately set hoplimit for every segment, since the |
| * user might want to change the value via setsockopt. |
| * Also, desired default hop limit might be changed via |
| * Neighbor Discovery. |
| */ |
| ip6->ip6_hlim = in6_selecthlim(tp->t_inpcb, NULL); |
| |
| /* TODO: IPv6 IP6TOS_ECT bit on */ |
| error = ip6_output(m, |
| tp->t_inpcb->in6p_outputopts, NULL, |
| ((so->so_options & SO_DONTROUTE) ? |
| IP_ROUTETOIF : 0), NULL, NULL, tp->t_inpcb); |
| } else |
| #endif /* INET6 */ |
| { |
| ip->ip_len = m->m_pkthdr.len; |
| #ifdef INET6 |
| if (tp->t_inpcb->inp_vflag & INP_IPV6PROTO) |
| ip->ip_ttl = in6_selecthlim(tp->t_inpcb, NULL); |
| #endif /* INET6 */ |
| /* |
| * If we do path MTU discovery, then we set DF on every packet. |
| * This might not be the best thing to do according to RFC3390 |
| * Section 2. However the tcp hostcache migitates the problem |
| * so it affects only the first tcp connection with a host. |
| */ |
| if (V_path_mtu_discovery) |
| ip->ip_off |= IP_DF; |
| |
| error = ip_output(m, tp->t_inpcb->inp_options, NULL, |
| ((so->so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 0, |
| tp->t_inpcb); |
| } |
| if (error) { |
| |
| /* |
| * We know that the packet was lost, so back out the |
| * sequence number advance, if any. |
| * |
| * If the error is EPERM the packet got blocked by the |
| * local firewall. Normally we should terminate the |
| * connection but the blocking may have been spurious |
| * due to a firewall reconfiguration cycle. So we treat |
| * it like a packet loss and let the retransmit timer and |
| * timeouts do their work over time. |
| * XXX: It is a POLA question whether calling tcp_drop right |
| * away would be the really correct behavior instead. |
| */ |
| if (((tp->t_flags & TF_FORCEDATA) == 0 || |
| !tcp_timer_active(tp, TT_PERSIST)) && |
| ((flags & TH_SYN) == 0) && |
| (error != EPERM)) { |
| if (sack_rxmit) { |
| p->rxmit -= len; |
| tp->sackhint.sack_bytes_rexmit -= len; |
| KASSERT(tp->sackhint.sack_bytes_rexmit >= 0, |
| ("sackhint bytes rtx >= 0")); |
| } else |
| tp->snd_nxt -= len; |
| } |
| out: |
| SOCKBUF_UNLOCK_ASSERT(&so->so_snd); /* Check gotos. */ |
| switch (error) { |
| case EPERM: |
| tp->t_softerror = error; |
| return (error); |
| case ENOBUFS: |
| if (!tcp_timer_active(tp, TT_REXMT) && |
| !tcp_timer_active(tp, TT_PERSIST)) |
| tcp_timer_activate(tp, TT_REXMT, tp->t_rxtcur); |
| tp->snd_cwnd = tp->t_maxseg; |
| return (0); |
| case EMSGSIZE: |
| /* |
| * For some reason the interface we used initially |
| * to send segments changed to another or lowered |
| * its MTU. |
| * |
| * tcp_mtudisc() will find out the new MTU and as |
| * its last action, initiate retransmission, so it |
| * is important to not do so here. |
| * |
| * If TSO was active we either got an interface |
| * without TSO capabilits or TSO was turned off. |
| * Disable it for this connection as too and |
| * immediatly retry with MSS sized segments generated |
| * by this function. |
| */ |
| if (tso) |
| tp->t_flags &= ~TF_TSO; |
| tcp_mtudisc(tp->t_inpcb, 0); |
| return (0); |
| case EHOSTDOWN: |
| case EHOSTUNREACH: |
| case ENETDOWN: |
| case ENETUNREACH: |
| if (TCPS_HAVERCVDSYN(tp->t_state)) { |
| tp->t_softerror = error; |
| return (0); |
| } |
| /* FALLTHROUGH */ |
| default: |
| return (error); |
| } |
| } |
| TCPSTAT_INC(tcps_sndtotal); |
| |
| /* |
| * Data sent (as far as we can tell). |
| * If this advertises a larger window than any other segment, |
| * then remember the size of the advertised window. |
| * Any pending ACK has now been sent. |
| */ |
| if (recwin > 0 && SEQ_GT(tp->rcv_nxt + recwin, tp->rcv_adv)) |
| tp->rcv_adv = tp->rcv_nxt + recwin; |
| tp->last_ack_sent = tp->rcv_nxt; |
| tp->t_flags &= ~(TF_ACKNOW | TF_DELACK); |
| if (tcp_timer_active(tp, TT_DELACK)) |
| tcp_timer_activate(tp, TT_DELACK, 0); |
| #if 0 |
| /* |
| * This completely breaks TCP if newreno is turned on. What happens |
| * is that if delayed-acks are turned on on the receiver, this code |
| * on the transmitter effectively destroys the TCP window, forcing |
| * it to four packets (1.5Kx4 = 6K window). |
| */ |
| if (sendalot && (!V_tcp_do_newreno || --maxburst)) |
| goto again; |
| #endif |
| if (sendalot) |
| goto again; |
| return (0); |
| } |
| |
| void |
| tcp_setpersist(struct tcpcb *tp) |
| { |
| int t = ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1; |
| int tt; |
| |
| if (tcp_timer_active(tp, TT_REXMT)) |
| panic("tcp_setpersist: retransmit pending"); |
| /* |
| * Start/restart persistance timer. |
| */ |
| TCPT_RANGESET(tt, t * tcp_backoff[tp->t_rxtshift], |
| TCPTV_PERSMIN, TCPTV_PERSMAX); |
| tcp_timer_activate(tp, TT_PERSIST, tt); |
| if (tp->t_rxtshift < TCP_MAXRXTSHIFT) |
| tp->t_rxtshift++; |
| } |
| |
| /* |
| * Insert TCP options according to the supplied parameters to the place |
| * optp in a consistent way. Can handle unaligned destinations. |
| * |
| * The order of the option processing is crucial for optimal packing and |
| * alignment for the scarce option space. |
| * |
| * The optimal order for a SYN/SYN-ACK segment is: |
| * MSS (4) + NOP (1) + Window scale (3) + SACK permitted (2) + |
| * Timestamp (10) + Signature (18) = 38 bytes out of a maximum of 40. |
| * |
| * The SACK options should be last. SACK blocks consume 8*n+2 bytes. |
| * So a full size SACK blocks option is 34 bytes (with 4 SACK blocks). |
| * At minimum we need 10 bytes (to generate 1 SACK block). If both |
| * TCP Timestamps (12 bytes) and TCP Signatures (18 bytes) are present, |
| * we only have 10 bytes for SACK options (40 - (12 + 18)). |
| */ |
| int |
| tcp_addoptions(struct tcpopt *to, u_char *optp) |
| { |
| u_int mask, optlen = 0; |
| |
| for (mask = 1; mask < TOF_MAXOPT; mask <<= 1) { |
| if ((to->to_flags & mask) != mask) |
| continue; |
| if (optlen == TCP_MAXOLEN) |
| break; |
| switch (to->to_flags & mask) { |
| case TOF_MSS: |
| while (optlen % 4) { |
| optlen += TCPOLEN_NOP; |
| *optp++ = TCPOPT_NOP; |
| } |
| if (TCP_MAXOLEN - optlen < TCPOLEN_MAXSEG) |
| continue; |
| optlen += TCPOLEN_MAXSEG; |
| *optp++ = TCPOPT_MAXSEG; |
| *optp++ = TCPOLEN_MAXSEG; |
| to->to_mss = htons(to->to_mss); |
| bcopy((u_char *)&to->to_mss, optp, sizeof(to->to_mss)); |
| optp += sizeof(to->to_mss); |
| break; |
| case TOF_SCALE: |
| while (!optlen || optlen % 2 != 1) { |
| optlen += TCPOLEN_NOP; |
| *optp++ = TCPOPT_NOP; |
| } |
| if (TCP_MAXOLEN - optlen < TCPOLEN_WINDOW) |
| continue; |
| optlen += TCPOLEN_WINDOW; |
| *optp++ = TCPOPT_WINDOW; |
| *optp++ = TCPOLEN_WINDOW; |
| *optp++ = to->to_wscale; |
| break; |
| case TOF_SACKPERM: |
| while (optlen % 2) { |
| optlen += TCPOLEN_NOP; |
| *optp++ = TCPOPT_NOP; |
| } |
| if (TCP_MAXOLEN - optlen < TCPOLEN_SACK_PERMITTED) |
| continue; |
| optlen += TCPOLEN_SACK_PERMITTED; |
| *optp++ = TCPOPT_SACK_PERMITTED; |
| *optp++ = TCPOLEN_SACK_PERMITTED; |
| break; |
| case TOF_TS: |
| while (!optlen || optlen % 4 != 2) { |
| optlen += TCPOLEN_NOP; |
| *optp++ = TCPOPT_NOP; |
| } |
| if (TCP_MAXOLEN - optlen < TCPOLEN_TIMESTAMP) |
| continue; |
| optlen += TCPOLEN_TIMESTAMP; |
| *optp++ = TCPOPT_TIMESTAMP; |
| *optp++ = TCPOLEN_TIMESTAMP; |
| to->to_tsval = htonl(to->to_tsval); |
| to->to_tsecr = htonl(to->to_tsecr); |
| bcopy((u_char *)&to->to_tsval, optp, sizeof(to->to_tsval)); |
| optp += sizeof(to->to_tsval); |
| bcopy((u_char *)&to->to_tsecr, optp, sizeof(to->to_tsecr)); |
| optp += sizeof(to->to_tsecr); |
| break; |
| case TOF_SIGNATURE: |
| { |
| int siglen = TCPOLEN_SIGNATURE - 2; |
| |
| while (!optlen || optlen % 4 != 2) { |
| optlen += TCPOLEN_NOP; |
| *optp++ = TCPOPT_NOP; |
| } |
| if (TCP_MAXOLEN - optlen < TCPOLEN_SIGNATURE) |
| continue; |
| optlen += TCPOLEN_SIGNATURE; |
| *optp++ = TCPOPT_SIGNATURE; |
| *optp++ = TCPOLEN_SIGNATURE; |
| to->to_signature = optp; |
| while (siglen--) |
| *optp++ = 0; |
| break; |
| } |
| case TOF_SACK: |
| { |
| int sackblks = 0; |
| struct sackblk *sack = (struct sackblk *)to->to_sacks; |
| tcp_seq sack_seq; |
| |
| while (!optlen || optlen % 4 != 2) { |
| optlen += TCPOLEN_NOP; |
| *optp++ = TCPOPT_NOP; |
| } |
| if (TCP_MAXOLEN - optlen < TCPOLEN_SACKHDR + TCPOLEN_SACK) |
| continue; |
| optlen += TCPOLEN_SACKHDR; |
| *optp++ = TCPOPT_SACK; |
| sackblks = min(to->to_nsacks, |
| (TCP_MAXOLEN - optlen) / TCPOLEN_SACK); |
| *optp++ = TCPOLEN_SACKHDR + sackblks * TCPOLEN_SACK; |
| while (sackblks--) { |
| sack_seq = htonl(sack->start); |
| bcopy((u_char *)&sack_seq, optp, sizeof(sack_seq)); |
| optp += sizeof(sack_seq); |
| sack_seq = htonl(sack->end); |
| bcopy((u_char *)&sack_seq, optp, sizeof(sack_seq)); |
| optp += sizeof(sack_seq); |
| optlen += TCPOLEN_SACK; |
| sack++; |
| } |
| TCPSTAT_INC(tcps_sack_send_blocks); |
| break; |
| } |
| default: |
| panic("%s: unknown TCP option type", __func__); |
| break; |
| } |
| } |
| |
| /* Terminate and pad TCP options to a 4 byte boundary. */ |
| if (optlen % 4) { |
| optlen += TCPOLEN_EOL; |
| *optp++ = TCPOPT_EOL; |
| } |
| /* |
| * According to RFC 793 (STD0007): |
| * "The content of the header beyond the End-of-Option option |
| * must be header padding (i.e., zero)." |
| * and later: "The padding is composed of zeros." |
| */ |
| while (optlen % 4) { |
| optlen += TCPOLEN_PAD; |
| *optp++ = TCPOPT_PAD; |
| } |
| |
| KASSERT(optlen <= TCP_MAXOLEN, ("%s: TCP options too long", __func__)); |
| return (optlen); |
| } |