/* * INET An implementation of the TCP/IP protocol suite for the LINUX * operating system. INET is implemented using the BSD Socket * interface as the means of communication with the user level. * * Implementation of the Transmission Control Protocol(TCP). * * Version: $Id: tcp.c,v 1.216 2002/02/01 22:01:04 davem Exp $ * * Authors: Ross Biro * Fred N. van Kempen, * Mark Evans, * Corey Minyard * Florian La Roche, * Charles Hedrick, * Linus Torvalds, * Alan Cox, * Matthew Dillon, * Arnt Gulbrandsen, * Jorge Cwik, * * Fixes: * Alan Cox : Numerous verify_area() calls * Alan Cox : Set the ACK bit on a reset * Alan Cox : Stopped it crashing if it closed while * sk->inuse=1 and was trying to connect * (tcp_err()). * Alan Cox : All icmp error handling was broken * pointers passed where wrong and the * socket was looked up backwards. Nobody * tested any icmp error code obviously. * Alan Cox : tcp_err() now handled properly. It * wakes people on errors. poll * behaves and the icmp error race * has gone by moving it into sock.c * Alan Cox : tcp_send_reset() fixed to work for * everything not just packets for * unknown sockets. * Alan Cox : tcp option processing. * Alan Cox : Reset tweaked (still not 100%) [Had * syn rule wrong] * Herp Rosmanith : More reset fixes * Alan Cox : No longer acks invalid rst frames. * Acking any kind of RST is right out. * Alan Cox : Sets an ignore me flag on an rst * receive otherwise odd bits of prattle * escape still * Alan Cox : Fixed another acking RST frame bug. * Should stop LAN workplace lockups. * Alan Cox : Some tidyups using the new skb list * facilities * Alan Cox : sk->keepopen now seems to work * Alan Cox : Pulls options out correctly on accepts * Alan Cox : Fixed assorted sk->rqueue->next errors * Alan Cox : PSH doesn't end a TCP read. Switched a * bit to skb ops. * Alan Cox : Tidied tcp_data to avoid a potential * nasty. * Alan Cox : Added some better commenting, as the * tcp is hard to follow * Alan Cox : Removed incorrect check for 20 * psh * Michael O'Reilly : ack < copied bug fix. * Johannes Stille : Misc tcp fixes (not all in yet). * Alan Cox : FIN with no memory -> CRASH * Alan Cox : Added socket option proto entries. * Also added awareness of them to accept. * Alan Cox : Added TCP options (SOL_TCP) * Alan Cox : Switched wakeup calls to callbacks, * so the kernel can layer network * sockets. * Alan Cox : Use ip_tos/ip_ttl settings. * Alan Cox : Handle FIN (more) properly (we hope). * Alan Cox : RST frames sent on unsynchronised * state ack error. * Alan Cox : Put in missing check for SYN bit. * Alan Cox : Added tcp_select_window() aka NET2E * window non shrink trick. * Alan Cox : Added a couple of small NET2E timer * fixes * Charles Hedrick : TCP fixes * Toomas Tamm : TCP window fixes * Alan Cox : Small URG fix to rlogin ^C ack fight * Charles Hedrick : Rewrote most of it to actually work * Linus : Rewrote tcp_read() and URG handling * completely * Gerhard Koerting: Fixed some missing timer handling * Matthew Dillon : Reworked TCP machine states as per RFC * Gerhard Koerting: PC/TCP workarounds * Adam Caldwell : Assorted timer/timing errors * Matthew Dillon : Fixed another RST bug * Alan Cox : Move to kernel side addressing changes. * Alan Cox : Beginning work on TCP fastpathing * (not yet usable) * Arnt Gulbrandsen: Turbocharged tcp_check() routine. * Alan Cox : TCP fast path debugging * Alan Cox : Window clamping * Michael Riepe : Bug in tcp_check() * Matt Dillon : More TCP improvements and RST bug fixes * Matt Dillon : Yet more small nasties remove from the * TCP code (Be very nice to this man if * tcp finally works 100%) 8) * Alan Cox : BSD accept semantics. * Alan Cox : Reset on closedown bug. * Peter De Schrijver : ENOTCONN check missing in tcp_sendto(). * Michael Pall : Handle poll() after URG properly in * all cases. * Michael Pall : Undo the last fix in tcp_read_urg() * (multi URG PUSH broke rlogin). * Michael Pall : Fix the multi URG PUSH problem in * tcp_readable(), poll() after URG * works now. * Michael Pall : recv(...,MSG_OOB) never blocks in the * BSD api. * Alan Cox : Changed the semantics of sk->socket to * fix a race and a signal problem with * accept() and async I/O. * Alan Cox : Relaxed the rules on tcp_sendto(). * Yury Shevchuk : Really fixed accept() blocking problem. * Craig I. Hagan : Allow for BSD compatible TIME_WAIT for * clients/servers which listen in on * fixed ports. * Alan Cox : Cleaned the above up and shrank it to * a sensible code size. * Alan Cox : Self connect lockup fix. * Alan Cox : No connect to multicast. * Ross Biro : Close unaccepted children on master * socket close. * Alan Cox : Reset tracing code. * Alan Cox : Spurious resets on shutdown. * Alan Cox : Giant 15 minute/60 second timer error * Alan Cox : Small whoops in polling before an * accept. * Alan Cox : Kept the state trace facility since * it's handy for debugging. * Alan Cox : More reset handler fixes. * Alan Cox : Started rewriting the code based on * the RFC's for other useful protocol * references see: Comer, KA9Q NOS, and * for a reference on the difference * between specifications and how BSD * works see the 4.4lite source. * A.N.Kuznetsov : Don't time wait on completion of tidy * close. * Linus Torvalds : Fin/Shutdown & copied_seq changes. * Linus Torvalds : Fixed BSD port reuse to work first syn * Alan Cox : Reimplemented timers as per the RFC * and using multiple timers for sanity. * Alan Cox : Small bug fixes, and a lot of new * comments. * Alan Cox : Fixed dual reader crash by locking * the buffers (much like datagram.c) * Alan Cox : Fixed stuck sockets in probe. A probe * now gets fed up of retrying without * (even a no space) answer. * Alan Cox : Extracted closing code better * Alan Cox : Fixed the closing state machine to * resemble the RFC. * Alan Cox : More 'per spec' fixes. * Jorge Cwik : Even faster checksumming. * Alan Cox : tcp_data() doesn't ack illegal PSH * only frames. At least one pc tcp stack * generates them. * Alan Cox : Cache last socket. * Alan Cox : Per route irtt. * Matt Day : poll()->select() match BSD precisely on error * Alan Cox : New buffers * Marc Tamsky : Various sk->prot->retransmits and * sk->retransmits misupdating fixed. * Fixed tcp_write_timeout: stuck close, * and TCP syn retries gets used now. * Mark Yarvis : In tcp_read_wakeup(), don't send an * ack if state is TCP_CLOSED. * Alan Cox : Look up device on a retransmit - routes may * change. Doesn't yet cope with MSS shrink right * but it's a start! * Marc Tamsky : Closing in closing fixes. * Mike Shaver : RFC1122 verifications. * Alan Cox : rcv_saddr errors. * Alan Cox : Block double connect(). * Alan Cox : Small hooks for enSKIP. * Alexey Kuznetsov: Path MTU discovery. * Alan Cox : Support soft errors. * Alan Cox : Fix MTU discovery pathological case * when the remote claims no mtu! * Marc Tamsky : TCP_CLOSE fix. * Colin (G3TNE) : Send a reset on syn ack replies in * window but wrong (fixes NT lpd problems) * Pedro Roque : Better TCP window handling, delayed ack. * Joerg Reuter : No modification of locked buffers in * tcp_do_retransmit() * Eric Schenk : Changed receiver side silly window * avoidance algorithm to BSD style * algorithm. This doubles throughput * against machines running Solaris, * and seems to result in general * improvement. * Stefan Magdalinski : adjusted tcp_readable() to fix FIONREAD * Willy Konynenberg : Transparent proxying support. * Mike McLagan : Routing by source * Keith Owens : Do proper merging with partial SKB's in * tcp_do_sendmsg to avoid burstiness. * Eric Schenk : Fix fast close down bug with * shutdown() followed by close(). * Andi Kleen : Make poll agree with SIGIO * Salvatore Sanfilippo : Support SO_LINGER with linger == 1 and * lingertime == 0 (RFC 793 ABORT Call) * Hirokazu Takahashi : Use copy_from_user() instead of * csum_and_copy_from_user() if possible. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or(at your option) any later version. * * Description of States: * * TCP_SYN_SENT sent a connection request, waiting for ack * * TCP_SYN_RECV received a connection request, sent ack, * waiting for final ack in three-way handshake. * * TCP_ESTABLISHED connection established * * TCP_FIN_WAIT1 our side has shutdown, waiting to complete * transmission of remaining buffered data * * TCP_FIN_WAIT2 all buffered data sent, waiting for remote * to shutdown * * TCP_CLOSING both sides have shutdown but we still have * data we have to finish sending * * TCP_TIME_WAIT timeout to catch resent junk before entering * closed, can only be entered from FIN_WAIT2 * or CLOSING. Required because the other end * may not have gotten our last ACK causing it * to retransmit the data packet (which we ignore) * * TCP_CLOSE_WAIT remote side has shutdown and is waiting for * us to finish writing our data and to shutdown * (we have to close() to move on to LAST_ACK) * * TCP_LAST_ACK out side has shutdown after remote has * shutdown. There may still be data in our * buffer that we have to finish sending * * TCP_CLOSE socket is finished */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include int sysctl_tcp_fin_timeout = TCP_FIN_TIMEOUT; DEFINE_SNMP_STAT(struct tcp_mib, tcp_statistics); kmem_cache_t *tcp_bucket_cachep; kmem_cache_t *tcp_timewait_cachep; atomic_t tcp_orphan_count = ATOMIC_INIT(0); int sysctl_tcp_mem[3]; int sysctl_tcp_wmem[3] = { 4 * 1024, 16 * 1024, 128 * 1024 }; int sysctl_tcp_rmem[3] = { 4 * 1024, 87380, 87380 * 2 }; EXPORT_SYMBOL(sysctl_tcp_mem); EXPORT_SYMBOL(sysctl_tcp_rmem); EXPORT_SYMBOL(sysctl_tcp_wmem); atomic_t tcp_memory_allocated; /* Current allocated memory. */ atomic_t tcp_sockets_allocated; /* Current number of TCP sockets. */ EXPORT_SYMBOL(tcp_memory_allocated); EXPORT_SYMBOL(tcp_sockets_allocated); /* * Pressure flag: try to collapse. * Technical note: it is used by multiple contexts non atomically. * All the sk_stream_mem_schedule() is of this nature: accounting * is strict, actions are advisory and have some latency. */ int tcp_memory_pressure; EXPORT_SYMBOL(tcp_memory_pressure); void tcp_enter_memory_pressure(void) { if (!tcp_memory_pressure) { NET_INC_STATS(LINUX_MIB_TCPMEMORYPRESSURES); tcp_memory_pressure = 1; } } EXPORT_SYMBOL(tcp_enter_memory_pressure); /* * LISTEN is a special case for poll.. */ static __inline__ unsigned int tcp_listen_poll(struct sock *sk, poll_table *wait) { return !reqsk_queue_empty(&tcp_sk(sk)->accept_queue) ? (POLLIN | POLLRDNORM) : 0; } /* * Wait for a TCP event. * * Note that we don't need to lock the socket, as the upper poll layers * take care of normal races (between the test and the event) and we don't * go look at any of the socket buffers directly. */ unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait) { unsigned int mask; struct sock *sk = sock->sk; struct tcp_sock *tp = tcp_sk(sk); poll_wait(file, sk->sk_sleep, wait); if (sk->sk_state == TCP_LISTEN) return tcp_listen_poll(sk, wait); /* Socket is not locked. We are protected from async events by poll logic and correct handling of state changes made by another threads is impossible in any case. */ mask = 0; if (sk->sk_err) mask = POLLERR; /* * POLLHUP is certainly not done right. But poll() doesn't * have a notion of HUP in just one direction, and for a * socket the read side is more interesting. * * Some poll() documentation says that POLLHUP is incompatible * with the POLLOUT/POLLWR flags, so somebody should check this * all. But careful, it tends to be safer to return too many * bits than too few, and you can easily break real applications * if you don't tell them that something has hung up! * * Check-me. * * Check number 1. POLLHUP is _UNMASKABLE_ event (see UNIX98 and * our fs/select.c). It means that after we received EOF, * poll always returns immediately, making impossible poll() on write() * in state CLOSE_WAIT. One solution is evident --- to set POLLHUP * if and only if shutdown has been made in both directions. * Actually, it is interesting to look how Solaris and DUX * solve this dilemma. I would prefer, if PULLHUP were maskable, * then we could set it on SND_SHUTDOWN. BTW examples given * in Stevens' books assume exactly this behaviour, it explains * why PULLHUP is incompatible with POLLOUT. --ANK * * NOTE. Check for TCP_CLOSE is added. The goal is to prevent * blocking on fresh not-connected or disconnected socket. --ANK */ if (sk->sk_shutdown == SHUTDOWN_MASK || sk->sk_state == TCP_CLOSE) mask |= POLLHUP; if (sk->sk_shutdown & RCV_SHUTDOWN) mask |= POLLIN | POLLRDNORM; /* Connected? */ if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV)) { /* Potential race condition. If read of tp below will * escape above sk->sk_state, we can be illegally awaken * in SYN_* states. */ if ((tp->rcv_nxt != tp->copied_seq) && (tp->urg_seq != tp->copied_seq || tp->rcv_nxt != tp->copied_seq + 1 || sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data)) mask |= POLLIN | POLLRDNORM; if (!(sk->sk_shutdown & SEND_SHUTDOWN)) { if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) { mask |= POLLOUT | POLLWRNORM; } else { /* send SIGIO later */ set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); /* Race breaker. If space is freed after * wspace test but before the flags are set, * IO signal will be lost. */ if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) mask |= POLLOUT | POLLWRNORM; } } if (tp->urg_data & TCP_URG_VALID) mask |= POLLPRI; } return mask; } int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg) { struct tcp_sock *tp = tcp_sk(sk); int answ; switch (cmd) { case SIOCINQ: if (sk->sk_state == TCP_LISTEN) return -EINVAL; lock_sock(sk); if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) answ = 0; else if (sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data || before(tp->urg_seq, tp->copied_seq) || !before(tp->urg_seq, tp->rcv_nxt)) { answ = tp->rcv_nxt - tp->copied_seq; /* Subtract 1, if FIN is in queue. */ if (answ && !skb_queue_empty(&sk->sk_receive_queue)) answ -= ((struct sk_buff *)sk->sk_receive_queue.prev)->h.th->fin; } else answ = tp->urg_seq - tp->copied_seq; release_sock(sk); break; case SIOCATMARK: answ = tp->urg_data && tp->urg_seq == tp->copied_seq; break; case SIOCOUTQ: if (sk->sk_state == TCP_LISTEN) return -EINVAL; if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) answ = 0; else answ = tp->write_seq - tp->snd_una; break; default: return -ENOIOCTLCMD; }; return put_user(answ, (int __user *)arg); } int tcp_listen_start(struct sock *sk) { struct inet_sock *inet = inet_sk(sk); struct tcp_sock *tp = tcp_sk(sk); int rc = reqsk_queue_alloc(&tp->accept_queue, TCP_SYNQ_HSIZE); if (rc != 0) return rc; sk->sk_max_ack_backlog = 0; sk->sk_ack_backlog = 0; tcp_delack_init(tp); /* There is race window here: we announce ourselves listening, * but this transition is still not validated by get_port(). * It is OK, because this socket enters to hash table only * after validation is complete. */ sk->sk_state = TCP_LISTEN; if (!sk->sk_prot->get_port(sk, inet->num)) { inet->sport = htons(inet->num); sk_dst_reset(sk); sk->sk_prot->hash(sk); return 0; } sk->sk_state = TCP_CLOSE; reqsk_queue_destroy(&tp->accept_queue); return -EADDRINUSE; } /* * This routine closes sockets which have been at least partially * opened, but not yet accepted. */ static void tcp_listen_stop (struct sock *sk) { struct tcp_sock *tp = tcp_sk(sk); struct listen_sock *lopt; struct request_sock *acc_req; struct request_sock *req; int i; tcp_delete_keepalive_timer(sk); /* make all the listen_opt local to us */ lopt = reqsk_queue_yank_listen_sk(&tp->accept_queue); acc_req = reqsk_queue_yank_acceptq(&tp->accept_queue); if (lopt->qlen) { for (i = 0; i < TCP_SYNQ_HSIZE; i++) { while ((req = lopt->syn_table[i]) != NULL) { lopt->syn_table[i] = req->dl_next; lopt->qlen--; reqsk_free(req); /* Following specs, it would be better either to send FIN * (and enter FIN-WAIT-1, it is normal close) * or to send active reset (abort). * Certainly, it is pretty dangerous while synflood, but it is * bad justification for our negligence 8) * To be honest, we are not able to make either * of the variants now. --ANK */ } } } BUG_TRAP(!lopt->qlen); kfree(lopt); while ((req = acc_req) != NULL) { struct sock *child = req->sk; acc_req = req->dl_next; local_bh_disable(); bh_lock_sock(child); BUG_TRAP(!sock_owned_by_user(child)); sock_hold(child); tcp_disconnect(child, O_NONBLOCK); sock_orphan(child); atomic_inc(&tcp_orphan_count); tcp_destroy_sock(child); bh_unlock_sock(child); local_bh_enable(); sock_put(child); sk_acceptq_removed(sk); __reqsk_free(req); } BUG_TRAP(!sk->sk_ack_backlog); } static inline void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb) { TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH; tp->pushed_seq = tp->write_seq; } static inline int forced_push(struct tcp_sock *tp) { return after(tp->write_seq, tp->pushed_seq + (tp->max_window >> 1)); } static inline void skb_entail(struct sock *sk, struct tcp_sock *tp, struct sk_buff *skb) { skb->csum = 0; TCP_SKB_CB(skb)->seq = tp->write_seq; TCP_SKB_CB(skb)->end_seq = tp->write_seq; TCP_SKB_CB(skb)->flags = TCPCB_FLAG_ACK; TCP_SKB_CB(skb)->sacked = 0; skb_header_release(skb); __skb_queue_tail(&sk->sk_write_queue, skb); sk_charge_skb(sk, skb); if (!sk->sk_send_head) sk->sk_send_head = skb; else if (tp->nonagle&TCP_NAGLE_PUSH) tp->nonagle &= ~TCP_NAGLE_PUSH; } static inline void tcp_mark_urg(struct tcp_sock *tp, int flags, struct sk_buff *skb) { if (flags & MSG_OOB) { tp->urg_mode = 1; tp->snd_up = tp->write_seq; TCP_SKB_CB(skb)->sacked |= TCPCB_URG; } } static inline void tcp_push(struct sock *sk, struct tcp_sock *tp, int flags, int mss_now, int nonagle) { if (sk->sk_send_head) { struct sk_buff *skb = sk->sk_write_queue.prev; if (!(flags & MSG_MORE) || forced_push(tp)) tcp_mark_push(tp, skb); tcp_mark_urg(tp, flags, skb); __tcp_push_pending_frames(sk, tp, mss_now, (flags & MSG_MORE) ? TCP_NAGLE_CORK : nonagle); } } static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffset, size_t psize, int flags) { struct tcp_sock *tp = tcp_sk(sk); int mss_now; int err; ssize_t copied; long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT); /* Wait for a connection to finish. */ if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) if ((err = sk_stream_wait_connect(sk, &timeo)) != 0) goto out_err; clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); mss_now = tcp_current_mss(sk, !(flags&MSG_OOB)); copied = 0; err = -EPIPE; if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) goto do_error; while (psize > 0) { struct sk_buff *skb = sk->sk_write_queue.prev; struct page *page = pages[poffset / PAGE_SIZE]; int copy, i, can_coalesce; int offset = poffset % PAGE_SIZE; int size = min_t(size_t, psize, PAGE_SIZE - offset); if (!sk->sk_send_head || (copy = mss_now - skb->len) <= 0) { new_segment: if (!sk_stream_memory_free(sk)) goto wait_for_sndbuf; skb = sk_stream_alloc_pskb(sk, 0, 0, sk->sk_allocation); if (!skb) goto wait_for_memory; skb_entail(sk, tp, skb); copy = mss_now; } if (copy > size) copy = size; i = skb_shinfo(skb)->nr_frags; can_coalesce = skb_can_coalesce(skb, i, page, offset); if (!can_coalesce && i >= MAX_SKB_FRAGS) { tcp_mark_push(tp, skb); goto new_segment; } if (sk->sk_forward_alloc < copy && !sk_stream_mem_schedule(sk, copy, 0)) goto wait_for_memory; if (can_coalesce) { skb_shinfo(skb)->frags[i - 1].size += copy; } else { get_page(page); skb_fill_page_desc(skb, i, page, offset, copy); } skb->len += copy; skb->data_len += copy; skb->truesize += copy; sk->sk_wmem_queued += copy; sk->sk_forward_alloc -= copy; skb->ip_summed = CHECKSUM_HW; tp->write_seq += copy; TCP_SKB_CB(skb)->end_seq += copy; skb_shinfo(skb)->tso_segs = 0; if (!copied) TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_PSH; copied += copy; poffset += copy; if (!(psize -= copy)) goto out; if (skb->len != mss_now || (flags & MSG_OOB)) continue; if (forced_push(tp)) { tcp_mark_push(tp, skb); __tcp_push_pending_frames(sk, tp, mss_now, TCP_NAGLE_PUSH); } else if (skb == sk->sk_send_head) tcp_push_one(sk, mss_now); continue; wait_for_sndbuf: set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); wait_for_memory: if (copied) tcp_push(sk, tp, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH); if ((err = sk_stream_wait_memory(sk, &timeo)) != 0) goto do_error; mss_now = tcp_current_mss(sk, !(flags&MSG_OOB)); } out: if (copied) tcp_push(sk, tp, flags, mss_now, tp->nonagle); return copied; do_error: if (copied) goto out; out_err: return sk_stream_error(sk, flags, err); } ssize_t tcp_sendpage(struct socket *sock, struct page *page, int offset, size_t size, int flags) { ssize_t res; struct sock *sk = sock->sk; #define TCP_ZC_CSUM_FLAGS (NETIF_F_IP_CSUM | NETIF_F_NO_CSUM | NETIF_F_HW_CSUM) if (!(sk->sk_route_caps & NETIF_F_SG) || !(sk->sk_route_caps & TCP_ZC_CSUM_FLAGS)) return sock_no_sendpage(sock, page, offset, size, flags); #undef TCP_ZC_CSUM_FLAGS lock_sock(sk); TCP_CHECK_TIMER(sk); res = do_tcp_sendpages(sk, &page, offset, size, flags); TCP_CHECK_TIMER(sk); release_sock(sk); return res; } #define TCP_PAGE(sk) (sk->sk_sndmsg_page) #define TCP_OFF(sk) (sk->sk_sndmsg_off) static inline int select_size(struct sock *sk, struct tcp_sock *tp) { int tmp = tp->mss_cache_std; if (sk->sk_route_caps & NETIF_F_SG) tmp = 0; return tmp; } int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, size_t size) { struct iovec *iov; struct tcp_sock *tp = tcp_sk(sk); struct sk_buff *skb; int iovlen, flags; int mss_now; int err, copied; long timeo; lock_sock(sk); TCP_CHECK_TIMER(sk); flags = msg->msg_flags; timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT); /* Wait for a connection to finish. */ if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) if ((err = sk_stream_wait_connect(sk, &timeo)) != 0) goto out_err; /* This should be in poll */ clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); mss_now = tcp_current_mss(sk, !(flags&MSG_OOB)); /* Ok commence sending. */ iovlen = msg->msg_iovlen; iov = msg->msg_iov; copied = 0; err = -EPIPE; if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) goto do_error; while (--iovlen >= 0) { int seglen = iov->iov_len; unsigned char __user *from = iov->iov_base; iov++; while (seglen > 0) { int copy; skb = sk->sk_write_queue.prev; if (!sk->sk_send_head || (copy = mss_now - skb->len) <= 0) { new_segment: /* Allocate new segment. If the interface is SG, * allocate skb fitting to single page. */ if (!sk_stream_memory_free(sk)) goto wait_for_sndbuf; skb = sk_stream_alloc_pskb(sk, select_size(sk, tp), 0, sk->sk_allocation); if (!skb) goto wait_for_memory; /* * Check whether we can use HW checksum. */ if (sk->sk_route_caps & (NETIF_F_IP_CSUM | NETIF_F_NO_CSUM | NETIF_F_HW_CSUM)) skb->ip_summed = CHECKSUM_HW; skb_entail(sk, tp, skb); copy = mss_now; } /* Try to append data to the end of skb. */ if (copy > seglen) copy = seglen; /* Where to copy to? */ if (skb_tailroom(skb) > 0) { /* We have some space in skb head. Superb! */ if (copy > skb_tailroom(skb)) copy = skb_tailroom(skb); if ((err = skb_add_data(skb, from, copy)) != 0) goto do_fault; } else { int merge = 0; int i = skb_shinfo(skb)->nr_frags; struct page *page = TCP_PAGE(sk); int off = TCP_OFF(sk); if (skb_can_coalesce(skb, i, page, off) && off != PAGE_SIZE) { /* We can extend the last page * fragment. */ merge = 1; } else if (i == MAX_SKB_FRAGS || (!i && !(sk->sk_route_caps & NETIF_F_SG))) { /* Need to add new fragment and cannot * do this because interface is non-SG, * or because all the page slots are * busy. */ tcp_mark_push(tp, skb); goto new_segment; } else if (page) { if (off == PAGE_SIZE) { put_page(page); TCP_PAGE(sk) = page = NULL; } } if (!page) { /* Allocate new cache page. */ if (!(page = sk_stream_alloc_page(sk))) goto wait_for_memory; off = 0; } if (copy > PAGE_SIZE - off) copy = PAGE_SIZE - off; /* Time to copy data. We are close to * the end! */ err = skb_copy_to_page(sk, from, skb, page, off, copy); if (err) { /* If this page was new, give it to the * socket so it does not get leaked. */ if (!TCP_PAGE(sk)) { TCP_PAGE(sk) = page; TCP_OFF(sk) = 0; } goto do_error; } /* Update the skb. */ if (merge) { skb_shinfo(skb)->frags[i - 1].size += copy; } else { skb_fill_page_desc(skb, i, page, off, copy); if (TCP_PAGE(sk)) { get_page(page); } else if (off + copy < PAGE_SIZE) { get_page(page); TCP_PAGE(sk) = page; } } TCP_OFF(sk) = off + copy; } if (!copied) TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_PSH; tp->write_seq += copy; TCP_SKB_CB(skb)->end_seq += copy; skb_shinfo(skb)->tso_segs = 0; from += copy; copied += copy; if ((seglen -= copy) == 0 && iovlen == 0) goto out; if (skb->len != mss_now || (flags & MSG_OOB)) continue; if (forced_push(tp)) { tcp_mark_push(tp, skb); __tcp_push_pending_frames(sk, tp, mss_now, TCP_NAGLE_PUSH); } else if (skb == sk->sk_send_head) tcp_push_one(sk, mss_now); continue; wait_for_sndbuf: set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); wait_for_memory: if (copied) tcp_push(sk, tp, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH); if ((err = sk_stream_wait_memory(sk, &timeo)) != 0) goto do_error; mss_now = tcp_current_mss(sk, !(flags&MSG_OOB)); } } out: if (copied) tcp_push(sk, tp, flags, mss_now, tp->nonagle); TCP_CHECK_TIMER(sk); release_sock(sk); return copied; do_fault: if (!skb->len) { if (sk->sk_send_head == skb) sk->sk_send_head = NULL; __skb_unlink(skb, skb->list); sk_stream_free_skb(sk, skb); } do_error: if (copied) goto out; out_err: err = sk_stream_error(sk, flags, err); TCP_CHECK_TIMER(sk); release_sock(sk); return err; } /* * Handle reading urgent data. BSD has very simple semantics for * this, no blocking and very strange errors 8) */ static int tcp_recv_urg(struct sock *sk, long timeo, struct msghdr *msg, int len, int flags, int *addr_len) { struct tcp_sock *tp = tcp_sk(sk); /* No URG data to read. */ if (sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data || tp->urg_data == TCP_URG_READ) return -EINVAL; /* Yes this is right ! */ if (sk->sk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DONE)) return -ENOTCONN; if (tp->urg_data & TCP_URG_VALID) { int err = 0; char c = tp->urg_data; if (!(flags & MSG_PEEK)) tp->urg_data = TCP_URG_READ; /* Read urgent data. */ msg->msg_flags |= MSG_OOB; if (len > 0) { if (!(flags & MSG_TRUNC)) err = memcpy_toiovec(msg->msg_iov, &c, 1); len = 1; } else msg->msg_flags |= MSG_TRUNC; return err ? -EFAULT : len; } if (sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN)) return 0; /* Fixed the recv(..., MSG_OOB) behaviour. BSD docs and * the available implementations agree in this case: * this call should never block, independent of the * blocking state of the socket. * Mike */ return -EAGAIN; } /* Clean up the receive buffer for full frames taken by the user, * then send an ACK if necessary. COPIED is the number of bytes * tcp_recvmsg has given to the user so far, it speeds up the * calculation of whether or not we must ACK for the sake of * a window update. */ static void cleanup_rbuf(struct sock *sk, int copied) { struct tcp_sock *tp = tcp_sk(sk); int time_to_ack = 0; #if TCP_DEBUG struct sk_buff *skb = skb_peek(&sk->sk_receive_queue); BUG_TRAP(!skb || before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq)); #endif if (tcp_ack_scheduled(tp)) { /* Delayed ACKs frequently hit locked sockets during bulk * receive. */ if (tp->ack.blocked || /* Once-per-two-segments ACK was not sent by tcp_input.c */ tp->rcv_nxt - tp->rcv_wup > tp->ack.rcv_mss || /* * If this read emptied read buffer, we send ACK, if * connection is not bidirectional, user drained * receive buffer and there was a small segment * in queue. */ (copied > 0 && (tp->ack.pending & TCP_ACK_PUSHED) && !tp->ack.pingpong && !atomic_read(&sk->sk_rmem_alloc))) time_to_ack = 1; } /* We send an ACK if we can now advertise a non-zero window * which has been raised "significantly". * * Even if window raised up to infinity, do not send window open ACK * in states, where we will not receive more. It is useless. */ if (copied > 0 && !time_to_ack && !(sk->sk_shutdown & RCV_SHUTDOWN)) { __u32 rcv_window_now = tcp_receive_window(tp); /* Optimize, __tcp_select_window() is not cheap. */ if (2*rcv_window_now <= tp->window_clamp) { __u32 new_window = __tcp_select_window(sk); /* Send ACK now, if this read freed lots of space * in our buffer. Certainly, new_window is new window. * We can advertise it now, if it is not less than current one. * "Lots" means "at least twice" here. */ if (new_window && new_window >= 2 * rcv_window_now) time_to_ack = 1; } } if (time_to_ack) tcp_send_ack(sk); } static void tcp_prequeue_process(struct sock *sk) { struct sk_buff *skb; struct tcp_sock *tp = tcp_sk(sk); NET_ADD_STATS_USER(LINUX_MIB_TCPPREQUEUED, skb_queue_len(&tp->ucopy.prequeue)); /* RX process wants to run with disabled BHs, though it is not * necessary */ local_bh_disable(); while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) sk->sk_backlog_rcv(sk, skb); local_bh_enable(); /* Clear memory counter. */ tp->ucopy.memory = 0; } static inline struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off) { struct sk_buff *skb; u32 offset; skb_queue_walk(&sk->sk_receive_queue, skb) { offset = seq - TCP_SKB_CB(skb)->seq; if (skb->h.th->syn) offset--; if (offset < skb->len || skb->h.th->fin) { *off = offset; return skb; } } return NULL; } /* * This routine provides an alternative to tcp_recvmsg() for routines * that would like to handle copying from skbuffs directly in 'sendfile' * fashion. * Note: * - It is assumed that the socket was locked by the caller. * - The routine does not block. * - At present, there is no support for reading OOB data * or for 'peeking' the socket using this routine * (although both would be easy to implement). */ int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, sk_read_actor_t recv_actor) { struct sk_buff *skb; struct tcp_sock *tp = tcp_sk(sk); u32 seq = tp->copied_seq; u32 offset; int copied = 0; if (sk->sk_state == TCP_LISTEN) return -ENOTCONN; while ((skb = tcp_recv_skb(sk, seq, &offset)) != NULL) { if (offset < skb->len) { size_t used, len; len = skb->len - offset; /* Stop reading if we hit a patch of urgent data */ if (tp->urg_data) { u32 urg_offset = tp->urg_seq - seq; if (urg_offset < len) len = urg_offset; if (!len) break; } used = recv_actor(desc, skb, offset, len); if (used <= len) { seq += used; copied += used; offset += used; } if (offset != skb->len) break; } if (skb->h.th->fin) { sk_eat_skb(sk, skb); ++seq; break; } sk_eat_skb(sk, skb); if (!desc->count) break; } tp->copied_seq = seq; tcp_rcv_space_adjust(sk); /* Clean up data we have read: This will do ACK frames. */ if (copied) cleanup_rbuf(sk, copied); return copied; } /* * This routine copies from a sock struct into the user buffer. * * Technical note: in 2.3 we work on _locked_ socket, so that * tricks with *seq access order and skb->users are not required. * Probably, code can be easily improved even more. */ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, size_t len, int nonblock, int flags, int *addr_len) { struct tcp_sock *tp = tcp_sk(sk); int copied = 0; u32 peek_seq; u32 *seq; unsigned long used; int err; int target; /* Read at least this many bytes */ long timeo; struct task_struct *user_recv = NULL; lock_sock(sk); TCP_CHECK_TIMER(sk); err = -ENOTCONN; if (sk->sk_state == TCP_LISTEN) goto out; timeo = sock_rcvtimeo(sk, nonblock); /* Urgent data needs to be handled specially. */ if (flags & MSG_OOB) goto recv_urg; seq = &tp->copied_seq; if (flags & MSG_PEEK) { peek_seq = tp->copied_seq; seq = &peek_seq; } target = sock_rcvlowat(sk, flags & MSG_WAITALL, len); do { struct sk_buff *skb; u32 offset; /* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */ if (tp->urg_data && tp->urg_seq == *seq) { if (copied) break; if (signal_pending(current)) { copied = timeo ? sock_intr_errno(timeo) : -EAGAIN; break; } } /* Next get a buffer. */ skb = skb_peek(&sk->sk_receive_queue); do { if (!skb) break; /* Now that we have two receive queues this * shouldn't happen. */ if (before(*seq, TCP_SKB_CB(skb)->seq)) { printk(KERN_INFO "recvmsg bug: copied %X " "seq %X\n", *seq, TCP_SKB_CB(skb)->seq); break; } offset = *seq - TCP_SKB_CB(skb)->seq; if (skb->h.th->syn) offset--; if (offset < skb->len) goto found_ok_skb; if (skb->h.th->fin) goto found_fin_ok; BUG_TRAP(flags & MSG_PEEK); skb = skb->next; } while (skb != (struct sk_buff *)&sk->sk_receive_queue); /* Well, if we have backlog, try to process it now yet. */ if (copied >= target && !sk->sk_backlog.tail) break; if (copied) { if (sk->sk_err || sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN) || !timeo || signal_pending(current) || (flags & MSG_PEEK)) break; } else { if (sock_flag(sk, SOCK_DONE)) break; if (sk->sk_err) { copied = sock_error(sk); break; } if (sk->sk_shutdown & RCV_SHUTDOWN) break; if (sk->sk_state == TCP_CLOSE) { if (!sock_flag(sk, SOCK_DONE)) { /* This occurs when user tries to read * from never connected socket. */ copied = -ENOTCONN; break; } break; } if (!timeo) { copied = -EAGAIN; break; } if (signal_pending(current)) { copied = sock_intr_errno(timeo); break; } } cleanup_rbuf(sk, copied); if (!sysctl_tcp_low_latency && tp->ucopy.task == user_recv) { /* Install new reader */ if (!user_recv && !(flags & (MSG_TRUNC | MSG_PEEK))) { user_recv = current; tp->ucopy.task = user_recv; tp->ucopy.iov = msg->msg_iov; } tp->ucopy.len = len; BUG_TRAP(tp->copied_seq == tp->rcv_nxt || (flags & (MSG_PEEK | MSG_TRUNC))); /* Ugly... If prequeue is not empty, we have to * process it before releasing socket, otherwise * order will be broken at second iteration. * More elegant solution is required!!! * * Look: we have the following (pseudo)queues: * * 1. packets in flight * 2. backlog * 3. prequeue * 4. receive_queue * * Each queue can be processed only if the next ones * are empty. At this point we have empty receive_queue. * But prequeue _can_ be not empty after 2nd iteration, * when we jumped to start of loop because backlog * processing added something to receive_queue. * We cannot release_sock(), because backlog contains * packets arrived _after_ prequeued ones. * * Shortly, algorithm is clear --- to process all * the queues in order. We could make it more directly, * requeueing packets from backlog to prequeue, if * is not empty. It is more elegant, but eats cycles, * unfortunately. */ if (skb_queue_len(&tp->ucopy.prequeue)) goto do_prequeue; /* __ Set realtime policy in scheduler __ */ } if (copied >= target) { /* Do not sleep, just process backlog. */ release_sock(sk); lock_sock(sk); } else sk_wait_data(sk, &timeo); if (user_recv) { int chunk; /* __ Restore normal policy in scheduler __ */ if ((chunk = len - tp->ucopy.len) != 0) { NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMBACKLOG, chunk); len -= chunk; copied += chunk; } if (tp->rcv_nxt == tp->copied_seq && skb_queue_len(&tp->ucopy.prequeue)) { do_prequeue: tcp_prequeue_process(sk); if ((chunk = len - tp->ucopy.len) != 0) { NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk); len -= chunk; copied += chunk; } } } if ((flags & MSG_PEEK) && peek_seq != tp->copied_seq) { if (net_ratelimit()) printk(KERN_DEBUG "TCP(%s:%d): Application bug, race in MSG_PEEK.\n", current->comm, current->pid); peek_seq = tp->copied_seq; } continue; found_ok_skb: /* Ok so how much can we use? */ used = skb->len - offset; if (len < used) used = len; /* Do we have urgent data here? */ if (tp->urg_data) { u32 urg_offset = tp->urg_seq - *seq; if (urg_offset < used) { if (!urg_offset) { if (!sock_flag(sk, SOCK_URGINLINE)) { ++*seq; offset++; used--; if (!used) goto skip_copy; } } else used = urg_offset; } } if (!(flags & MSG_TRUNC)) { err = skb_copy_datagram_iovec(skb, offset, msg->msg_iov, used); if (err) { /* Exception. Bailout! */ if (!copied) copied = -EFAULT; break; } } *seq += used; copied += used; len -= used; tcp_rcv_space_adjust(sk); skip_copy: if (tp->urg_data && after(tp->copied_seq, tp->urg_seq)) { tp->urg_data = 0; tcp_fast_path_check(sk, tp); } if (used + offset < skb->len) continue; if (skb->h.th->fin) goto found_fin_ok; if (!(flags & MSG_PEEK)) sk_eat_skb(sk, skb); continue; found_fin_ok: /* Process the FIN. */ ++*seq; if (!(flags & MSG_PEEK)) sk_eat_skb(sk, skb); break; } while (len > 0); if (user_recv) { if (skb_queue_len(&tp->ucopy.prequeue)) { int chunk; tp->ucopy.len = copied > 0 ? len : 0; tcp_prequeue_process(sk); if (copied > 0 && (chunk = len - tp->ucopy.len) != 0) { NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk); len -= chunk; copied += chunk; } } tp->ucopy.task = NULL; tp->ucopy.len = 0; } /* According to UNIX98, msg_name/msg_namelen are ignored * on connected socket. I was just happy when found this 8) --ANK */ /* Clean up data we have read: This will do ACK frames. */ cleanup_rbuf(sk, copied); TCP_CHECK_TIMER(sk); release_sock(sk); return copied; out: TCP_CHECK_TIMER(sk); release_sock(sk); return err; recv_urg: err = tcp_recv_urg(sk, timeo, msg, len, flags, addr_len); goto out; } /* * State processing on a close. This implements the state shift for * sending our FIN frame. Note that we only send a FIN for some * states. A shutdown() may have already sent the FIN, or we may be * closed. */ static unsigned char new_state[16] = { /* current state: new state: action: */ /* (Invalid) */ TCP_CLOSE, /* TCP_ESTABLISHED */ TCP_FIN_WAIT1 | TCP_ACTION_FIN, /* TCP_SYN_SENT */ TCP_CLOSE, /* TCP_SYN_RECV */ TCP_FIN_WAIT1 | TCP_ACTION_FIN, /* TCP_FIN_WAIT1 */ TCP_FIN_WAIT1, /* TCP_FIN_WAIT2 */ TCP_FIN_WAIT2, /* TCP_TIME_WAIT */ TCP_CLOSE, /* TCP_CLOSE */ TCP_CLOSE, /* TCP_CLOSE_WAIT */ TCP_LAST_ACK | TCP_ACTION_FIN, /* TCP_LAST_ACK */ TCP_LAST_ACK, /* TCP_LISTEN */ TCP_CLOSE, /* TCP_CLOSING */ TCP_CLOSING, }; static int tcp_close_state(struct sock *sk) { int next = (int)new_state[sk->sk_state]; int ns = next & TCP_STATE_MASK; tcp_set_state(sk, ns); return next & TCP_ACTION_FIN; } /* * Shutdown the sending side of a connection. Much like close except * that we don't receive shut down or set_sock_flag(sk, SOCK_DEAD). */ void tcp_shutdown(struct sock *sk, int how) { /* We need to grab some memory, and put together a FIN, * and then put it into the queue to be sent. * Tim MacKenzie(tym@dibbler.cs.monash.edu.au) 4 Dec '92. */ if (!(how & SEND_SHUTDOWN)) return; /* If we've already sent a FIN, or it's a closed state, skip this. */ if ((1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_SYN_SENT | TCPF_SYN_RECV | TCPF_CLOSE_WAIT)) { /* Clear out any half completed packets. FIN if needed. */ if (tcp_close_state(sk)) tcp_send_fin(sk); } } /* * At this point, there should be no process reference to this * socket, and thus no user references at all. Therefore we * can assume the socket waitqueue is inactive and nobody will * try to jump onto it. */ void tcp_destroy_sock(struct sock *sk) { BUG_TRAP(sk->sk_state == TCP_CLOSE); BUG_TRAP(sock_flag(sk, SOCK_DEAD)); /* It cannot be in hash table! */ BUG_TRAP(sk_unhashed(sk)); /* If it has not 0 inet_sk(sk)->num, it must be bound */ BUG_TRAP(!inet_sk(sk)->num || tcp_sk(sk)->bind_hash); sk->sk_prot->destroy(sk); sk_stream_kill_queues(sk); xfrm_sk_free_policy(sk); #ifdef INET_REFCNT_DEBUG if (atomic_read(&sk->sk_refcnt) != 1) { printk(KERN_DEBUG "Destruction TCP %p delayed, c=%d\n", sk, atomic_read(&sk->sk_refcnt)); } #endif atomic_dec(&tcp_orphan_count); sock_put(sk); } void tcp_close(struct sock *sk, long timeout) { struct sk_buff *skb; int data_was_unread = 0; lock_sock(sk); sk->sk_shutdown = SHUTDOWN_MASK; if (sk->sk_state == TCP_LISTEN) { tcp_set_state(sk, TCP_CLOSE); /* Special case. */ tcp_listen_stop(sk); goto adjudge_to_death; } /* We need to flush the recv. buffs. We do this only on the * descriptor close, not protocol-sourced closes, because the * reader process may not have drained the data yet! */ while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) { u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq - skb->h.th->fin; data_was_unread += len; __kfree_skb(skb); } sk_stream_mem_reclaim(sk); /* As outlined in draft-ietf-tcpimpl-prob-03.txt, section * 3.10, we send a RST here because data was lost. To * witness the awful effects of the old behavior of always * doing a FIN, run an older 2.1.x kernel or 2.0.x, start * a bulk GET in an FTP client, suspend the process, wait * for the client to advertise a zero window, then kill -9 * the FTP client, wheee... Note: timeout is always zero * in such a case. */ if (data_was_unread) { /* Unread data was tossed, zap the connection. */ NET_INC_STATS_USER(LINUX_MIB_TCPABORTONCLOSE); tcp_set_state(sk, TCP_CLOSE); tcp_send_active_reset(sk, GFP_KERNEL); } else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) { /* Check zero linger _after_ checking for unread data. */ sk->sk_prot->disconnect(sk, 0); NET_INC_STATS_USER(LINUX_MIB_TCPABORTONDATA); } else if (tcp_close_state(sk)) { /* We FIN if the application ate all the data before * zapping the connection. */ /* RED-PEN. Formally speaking, we have broken TCP state * machine. State transitions: * * TCP_ESTABLISHED -> TCP_FIN_WAIT1 * TCP_SYN_RECV -> TCP_FIN_WAIT1 (forget it, it's impossible) * TCP_CLOSE_WAIT -> TCP_LAST_ACK * * are legal only when FIN has been sent (i.e. in window), * rather than queued out of window. Purists blame. * * F.e. "RFC state" is ESTABLISHED, * if Linux state is FIN-WAIT-1, but FIN is still not sent. * * The visible declinations are that sometimes * we enter time-wait state, when it is not required really * (harmless), do not send active resets, when they are * required by specs (TCP_ESTABLISHED, TCP_CLOSE_WAIT, when * they look as CLOSING or LAST_ACK for Linux) * Probably, I missed some more holelets. * --ANK */ tcp_send_fin(sk); } sk_stream_wait_close(sk, timeout); adjudge_to_death: /* It is the last release_sock in its life. It will remove backlog. */ release_sock(sk); /* Now socket is owned by kernel and we acquire BH lock to finish close. No need to check for user refs. */ local_bh_disable(); bh_lock_sock(sk); BUG_TRAP(!sock_owned_by_user(sk)); sock_hold(sk); sock_orphan(sk); /* This is a (useful) BSD violating of the RFC. There is a * problem with TCP as specified in that the other end could * keep a socket open forever with no application left this end. * We use a 3 minute timeout (about the same as BSD) then kill * our end. If they send after that then tough - BUT: long enough * that we won't make the old 4*rto = almost no time - whoops * reset mistake. * * Nope, it was not mistake. It is really desired behaviour * f.e. on http servers, when such sockets are useless, but * consume significant resources. Let's do it with special * linger2 option. --ANK */ if (sk->sk_state == TCP_FIN_WAIT2) { struct tcp_sock *tp = tcp_sk(sk); if (tp->linger2 < 0) { tcp_set_state(sk, TCP_CLOSE); tcp_send_active_reset(sk, GFP_ATOMIC); NET_INC_STATS_BH(LINUX_MIB_TCPABORTONLINGER); } else { int tmo = tcp_fin_time(tp); if (tmo > TCP_TIMEWAIT_LEN) { tcp_reset_keepalive_timer(sk, tcp_fin_time(tp)); } else { atomic_inc(&tcp_orphan_count); tcp_time_wait(sk, TCP_FIN_WAIT2, tmo); goto out; } } } if (sk->sk_state != TCP_CLOSE) { sk_stream_mem_reclaim(sk); if (atomic_read(&tcp_orphan_count) > sysctl_tcp_max_orphans || (sk->sk_wmem_queued > SOCK_MIN_SNDBUF && atomic_read(&tcp_memory_allocated) > sysctl_tcp_mem[2])) { if (net_ratelimit()) printk(KERN_INFO "TCP: too many of orphaned " "sockets\n"); tcp_set_state(sk, TCP_CLOSE); tcp_send_active_reset(sk, GFP_ATOMIC); NET_INC_STATS_BH(LINUX_MIB_TCPABORTONMEMORY); } } atomic_inc(&tcp_orphan_count); if (sk->sk_state == TCP_CLOSE) tcp_destroy_sock(sk); /* Otherwise, socket is reprieved until protocol close. */ out: bh_unlock_sock(sk); local_bh_enable(); sock_put(sk); } /* These states need RST on ABORT according to RFC793 */ static inline int tcp_need_reset(int state) { return (1 << state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_FIN_WAIT1 | TCPF_FIN_WAIT2 | TCPF_SYN_RECV); } int tcp_disconnect(struct sock *sk, int flags) { struct inet_sock *inet = inet_sk(sk); struct tcp_sock *tp = tcp_sk(sk); int err = 0; int old_state = sk->sk_state; if (old_state != TCP_CLOSE) tcp_set_state(sk, TCP_CLOSE); /* ABORT function of RFC793 */ if (old_state == TCP_LISTEN) { tcp_listen_stop(sk); } else if (tcp_need_reset(old_state) || (tp->snd_nxt != tp->write_seq && (1 << old_state) & (TCPF_CLOSING | TCPF_LAST_ACK))) { /* The last check adjusts for discrepance of Linux wrt. RFC * states */ tcp_send_active_reset(sk, gfp_any()); sk->sk_err = ECONNRESET; } else if (old_state == TCP_SYN_SENT) sk->sk_err = ECONNRESET; tcp_clear_xmit_timers(sk); __skb_queue_purge(&sk->sk_receive_queue); sk_stream_writequeue_purge(sk); __skb_queue_purge(&tp->out_of_order_queue); inet->dport = 0; if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK)) inet_reset_saddr(sk); sk->sk_shutdown = 0; sock_reset_flag(sk, SOCK_DONE); tp->srtt = 0; if ((tp->write_seq += tp->max_window + 2) == 0) tp->write_seq = 1; tp->backoff = 0; tp->snd_cwnd = 2; tp->probes_out = 0; tp->packets_out = 0; tp->snd_ssthresh = 0x7fffffff; tp->snd_cwnd_cnt = 0; tcp_set_ca_state(tp, TCP_CA_Open); tcp_clear_retrans(tp); tcp_delack_init(tp); sk->sk_send_head = NULL; tp->rx_opt.saw_tstamp = 0; tcp_sack_reset(&tp->rx_opt); __sk_dst_reset(sk); BUG_TRAP(!inet->num || tp->bind_hash); sk->sk_error_report(sk); return err; } /* * Wait for an incoming connection, avoid race * conditions. This must be called with the socket locked. */ static int wait_for_connect(struct sock *sk, long timeo) { struct tcp_sock *tp = tcp_sk(sk); DEFINE_WAIT(wait); int err; /* * True wake-one mechanism for incoming connections: only * one process gets woken up, not the 'whole herd'. * Since we do not 'race & poll' for established sockets * anymore, the common case will execute the loop only once. * * Subtle issue: "add_wait_queue_exclusive()" will be added * after any current non-exclusive waiters, and we know that * it will always _stay_ after any new non-exclusive waiters * because all non-exclusive waiters are added at the * beginning of the wait-queue. As such, it's ok to "drop" * our exclusiveness temporarily when we get woken up without * having to remove and re-insert us on the wait queue. */ for (;;) { prepare_to_wait_exclusive(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE); release_sock(sk); if (reqsk_queue_empty(&tp->accept_queue)) timeo = schedule_timeout(timeo); lock_sock(sk); err = 0; if (!reqsk_queue_empty(&tp->accept_queue)) break; err = -EINVAL; if (sk->sk_state != TCP_LISTEN) break; err = sock_intr_errno(timeo); if (signal_pending(current)) break; err = -EAGAIN; if (!timeo) break; } finish_wait(sk->sk_sleep, &wait); return err; } /* * This will accept the next outstanding connection. */ struct sock *tcp_accept(struct sock *sk, int flags, int *err) { struct tcp_sock *tp = tcp_sk(sk); struct sock *newsk; int error; lock_sock(sk); /* We need to make sure that this socket is listening, * and that it has something pending. */ error = -EINVAL; if (sk->sk_state != TCP_LISTEN) goto out_err; /* Find already established connection */ if (reqsk_queue_empty(&tp->accept_queue)) { long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK); /* If this is a non blocking socket don't sleep */ error = -EAGAIN; if (!timeo) goto out_err; error = wait_for_connect(sk, timeo); if (error) goto out_err; } newsk = reqsk_queue_get_child(&tp->accept_queue, sk); BUG_TRAP(newsk->sk_state != TCP_SYN_RECV); out: release_sock(sk); return newsk; out_err: newsk = NULL; *err = error; goto out; } /* * Socket option code for TCP. */ int tcp_setsockopt(struct sock *sk, int level, int optname, char __user *optval, int optlen) { struct tcp_sock *tp = tcp_sk(sk); int val; int err = 0; if (level != SOL_TCP) return tp->af_specific->setsockopt(sk, level, optname, optval, optlen); /* This is a string value all the others are int's */ if (optname == TCP_CONGESTION) { char name[TCP_CA_NAME_MAX]; if (optlen < 1) return -EINVAL; val = strncpy_from_user(name, optval, min(TCP_CA_NAME_MAX-1, optlen)); if (val < 0) return -EFAULT; name[val] = 0; lock_sock(sk); err = tcp_set_congestion_control(tp, name); release_sock(sk); return err; } if (optlen < sizeof(int)) return -EINVAL; if (get_user(val, (int __user *)optval)) return -EFAULT; lock_sock(sk); switch (optname) { case TCP_MAXSEG: /* Values greater than interface MTU won't take effect. However * at the point when this call is done we typically don't yet * know which interface is going to be used */ if (val < 8 || val > MAX_TCP_WINDOW) { err = -EINVAL; break; } tp->rx_opt.user_mss = val; break; case TCP_NODELAY: if (val) { /* TCP_NODELAY is weaker than TCP_CORK, so that * this option on corked socket is remembered, but * it is not activated until cork is cleared. * * However, when TCP_NODELAY is set we make * an explicit push, which overrides even TCP_CORK * for currently queued segments. */ tp->nonagle |= TCP_NAGLE_OFF|TCP_NAGLE_PUSH; tcp_push_pending_frames(sk, tp); } else { tp->nonagle &= ~TCP_NAGLE_OFF; } break; case TCP_CORK: /* When set indicates to always queue non-full frames. * Later the user clears this option and we transmit * any pending partial frames in the queue. This is * meant to be used alongside sendfile() to get properly * filled frames when the user (for example) must write * out headers with a write() call first and then use * sendfile to send out the data parts. * * TCP_CORK can be set together with TCP_NODELAY and it is * stronger than TCP_NODELAY. */ if (val) { tp->nonagle |= TCP_NAGLE_CORK; } else { tp->nonagle &= ~TCP_NAGLE_CORK; if (tp->nonagle&TCP_NAGLE_OFF) tp->nonagle |= TCP_NAGLE_PUSH; tcp_push_pending_frames(sk, tp); } break; case TCP_KEEPIDLE: if (val < 1 || val > MAX_TCP_KEEPIDLE) err = -EINVAL; else { tp->keepalive_time = val * HZ; if (sock_flag(sk, SOCK_KEEPOPEN) && !((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN))) { __u32 elapsed = tcp_time_stamp - tp->rcv_tstamp; if (tp->keepalive_time > elapsed) elapsed = tp->keepalive_time - elapsed; else elapsed = 0; tcp_reset_keepalive_timer(sk, elapsed); } } break; case TCP_KEEPINTVL: if (val < 1 || val > MAX_TCP_KEEPINTVL) err = -EINVAL; else tp->keepalive_intvl = val * HZ; break; case TCP_KEEPCNT: if (val < 1 || val > MAX_TCP_KEEPCNT) err = -EINVAL; else tp->keepalive_probes = val; break; case TCP_SYNCNT: if (val < 1 || val > MAX_TCP_SYNCNT) err = -EINVAL; else tp->syn_retries = val; break; case TCP_LINGER2: if (val < 0) tp->linger2 = -1; else if (val > sysctl_tcp_fin_timeout / HZ) tp->linger2 = 0; else tp->linger2 = val * HZ; break; case TCP_DEFER_ACCEPT: tp->defer_accept = 0; if (val > 0) { /* Translate value in seconds to number of * retransmits */ while (tp->defer_accept < 32 && val > ((TCP_TIMEOUT_INIT / HZ) << tp->defer_accept)) tp->defer_accept++; tp->defer_accept++; } break; case TCP_WINDOW_CLAMP: if (!val) { if (sk->sk_state != TCP_CLOSE) { err = -EINVAL; break; } tp->window_clamp = 0; } else tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ? SOCK_MIN_RCVBUF / 2 : val; break; case TCP_QUICKACK: if (!val) { tp->ack.pingpong = 1; } else { tp->ack.pingpong = 0; if ((1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT) && tcp_ack_scheduled(tp)) { tp->ack.pending |= TCP_ACK_PUSHED; cleanup_rbuf(sk, 1); if (!(val & 1)) tp->ack.pingpong = 1; } } break; default: err = -ENOPROTOOPT; break; }; release_sock(sk); return err; } /* Return information about state of tcp endpoint in API format. */ void tcp_get_info(struct sock *sk, struct tcp_info *info) { struct tcp_sock *tp = tcp_sk(sk); u32 now = tcp_time_stamp; memset(info, 0, sizeof(*info)); info->tcpi_state = sk->sk_state; info->tcpi_ca_state = tp->ca_state; info->tcpi_retransmits = tp->retransmits; info->tcpi_probes = tp->probes_out; info->tcpi_backoff = tp->backoff; if (tp->rx_opt.tstamp_ok) info->tcpi_options |= TCPI_OPT_TIMESTAMPS; if (tp->rx_opt.sack_ok) info->tcpi_options |= TCPI_OPT_SACK; if (tp->rx_opt.wscale_ok) { info->tcpi_options |= TCPI_OPT_WSCALE; info->tcpi_snd_wscale = tp->rx_opt.snd_wscale; info->tcpi_rcv_wscale = tp->rx_opt.rcv_wscale; } if (tp->ecn_flags&TCP_ECN_OK) info->tcpi_options |= TCPI_OPT_ECN; info->tcpi_rto = jiffies_to_usecs(tp->rto); info->tcpi_ato = jiffies_to_usecs(tp->ack.ato); info->tcpi_snd_mss = tp->mss_cache_std; info->tcpi_rcv_mss = tp->ack.rcv_mss; info->tcpi_unacked = tp->packets_out; info->tcpi_sacked = tp->sacked_out; info->tcpi_lost = tp->lost_out; info->tcpi_retrans = tp->retrans_out; info->tcpi_fackets = tp->fackets_out; info->tcpi_last_data_sent = jiffies_to_msecs(now - tp->lsndtime); info->tcpi_last_data_recv = jiffies_to_msecs(now - tp->ack.lrcvtime); info->tcpi_last_ack_recv = jiffies_to_msecs(now - tp->rcv_tstamp); info->tcpi_pmtu = tp->pmtu_cookie; info->tcpi_rcv_ssthresh = tp->rcv_ssthresh; info->tcpi_rtt = jiffies_to_usecs(tp->srtt)>>3; info->tcpi_rttvar = jiffies_to_usecs(tp->mdev)>>2; info->tcpi_snd_ssthresh = tp->snd_ssthresh; info->tcpi_snd_cwnd = tp->snd_cwnd; info->tcpi_advmss = tp->advmss; info->tcpi_reordering = tp->reordering; info->tcpi_rcv_rtt = jiffies_to_usecs(tp->rcv_rtt_est.rtt)>>3; info->tcpi_rcv_space = tp->rcvq_space.space; info->tcpi_total_retrans = tp->total_retrans; } EXPORT_SYMBOL_GPL(tcp_get_info); int tcp_getsockopt(struct sock *sk, int level, int optname, char __user *optval, int __user *optlen) { struct tcp_sock *tp = tcp_sk(sk); int val, len; if (level != SOL_TCP) return tp->af_specific->getsockopt(sk, level, optname, optval, optlen); if (get_user(len, optlen)) return -EFAULT; len = min_t(unsigned int, len, sizeof(int)); if (len < 0) return -EINVAL; switch (optname) { case TCP_MAXSEG: val = tp->mss_cache_std; if (!val && ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN))) val = tp->rx_opt.user_mss; break; case TCP_NODELAY: val = !!(tp->nonagle&TCP_NAGLE_OFF); break; case TCP_CORK: val = !!(tp->nonagle&TCP_NAGLE_CORK); break; case TCP_KEEPIDLE: val = (tp->keepalive_time ? : sysctl_tcp_keepalive_time) / HZ; break; case TCP_KEEPINTVL: val = (tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl) / HZ; break; case TCP_KEEPCNT: val = tp->keepalive_probes ? : sysctl_tcp_keepalive_probes; break; case TCP_SYNCNT: val = tp->syn_retries ? : sysctl_tcp_syn_retries; break; case TCP_LINGER2: val = tp->linger2; if (val >= 0) val = (val ? : sysctl_tcp_fin_timeout) / HZ; break; case TCP_DEFER_ACCEPT: val = !tp->defer_accept ? 0 : ((TCP_TIMEOUT_INIT / HZ) << (tp->defer_accept - 1)); break; case TCP_WINDOW_CLAMP: val = tp->window_clamp; break; case TCP_INFO: { struct tcp_info info; if (get_user(len, optlen)) return -EFAULT; tcp_get_info(sk, &info); len = min_t(unsigned int, len, sizeof(info)); if (put_user(len, optlen)) return -EFAULT; if (copy_to_user(optval, &info, len)) return -EFAULT; return 0; } case TCP_QUICKACK: val = !tp->ack.pingpong; break; case TCP_CONGESTION: if (get_user(len, optlen)) return -EFAULT; len = min_t(unsigned int, len, TCP_CA_NAME_MAX); if (put_user(len, optlen)) return -EFAULT; if (copy_to_user(optval, tp->ca_ops->name, len)) return -EFAULT; return 0; default: return -ENOPROTOOPT; }; if (put_user(len, optlen)) return -EFAULT; if (copy_to_user(optval, &val, len)) return -EFAULT; return 0; } extern void __skb_cb_too_small_for_tcp(int, int); extern struct tcp_congestion_ops tcp_reno; static __initdata unsigned long thash_entries; static int __init set_thash_entries(char *str) { if (!str) return 0; thash_entries = simple_strtoul(str, &str, 0); return 1; } __setup("thash_entries=", set_thash_entries); void __init tcp_init(void) { struct sk_buff *skb = NULL; int order, i; if (sizeof(struct tcp_skb_cb) > sizeof(skb->cb)) __skb_cb_too_small_for_tcp(sizeof(struct tcp_skb_cb), sizeof(skb->cb)); tcp_bucket_cachep = kmem_cache_create("tcp_bind_bucket", sizeof(struct tcp_bind_bucket), 0, SLAB_HWCACHE_ALIGN, NULL, NULL); if (!tcp_bucket_cachep) panic("tcp_init: Cannot alloc tcp_bind_bucket cache."); tcp_timewait_cachep = kmem_cache_create("tcp_tw_bucket", sizeof(struct tcp_tw_bucket), 0, SLAB_HWCACHE_ALIGN, NULL, NULL); if (!tcp_timewait_cachep) panic("tcp_init: Cannot alloc tcp_tw_bucket cache."); /* Size and allocate the main established and bind bucket * hash tables. * * The methodology is similar to that of the buffer cache. */ tcp_ehash = (struct tcp_ehash_bucket *) alloc_large_system_hash("TCP established", sizeof(struct tcp_ehash_bucket), thash_entries, (num_physpages >= 128 * 1024) ? (25 - PAGE_SHIFT) : (27 - PAGE_SHIFT), HASH_HIGHMEM, &tcp_ehash_size, NULL, 0); tcp_ehash_size = (1 << tcp_ehash_size) >> 1; for (i = 0; i < (tcp_ehash_size << 1); i++) { rwlock_init(&tcp_ehash[i].lock); INIT_HLIST_HEAD(&tcp_ehash[i].chain); } tcp_bhash = (struct tcp_bind_hashbucket *) alloc_large_system_hash("TCP bind", sizeof(struct tcp_bind_hashbucket), tcp_ehash_size, (num_physpages >= 128 * 1024) ? (25 - PAGE_SHIFT) : (27 - PAGE_SHIFT), HASH_HIGHMEM, &tcp_bhash_size, NULL, 64 * 1024); tcp_bhash_size = 1 << tcp_bhash_size; for (i = 0; i < tcp_bhash_size; i++) { spin_lock_init(&tcp_bhash[i].lock); INIT_HLIST_HEAD(&tcp_bhash[i].chain); } /* Try to be a bit smarter and adjust defaults depending * on available memory. */ for (order = 0; ((1 << order) << PAGE_SHIFT) < (tcp_bhash_size * sizeof(struct tcp_bind_hashbucket)); order++) ; if (order >= 4) { sysctl_local_port_range[0] = 32768; sysctl_local_port_range[1] = 61000; sysctl_tcp_max_tw_buckets = 180000; sysctl_tcp_max_orphans = 4096 << (order - 4); sysctl_max_syn_backlog = 1024; } else if (order < 3) { sysctl_local_port_range[0] = 1024 * (3 - order); sysctl_tcp_max_tw_buckets >>= (3 - order); sysctl_tcp_max_orphans >>= (3 - order); sysctl_max_syn_backlog = 128; } tcp_port_rover = sysctl_local_port_range[0] - 1; sysctl_tcp_mem[0] = 768 << order; sysctl_tcp_mem[1] = 1024 << order; sysctl_tcp_mem[2] = 1536 << order; if (order < 3) { sysctl_tcp_wmem[2] = 64 * 1024; sysctl_tcp_rmem[0] = PAGE_SIZE; sysctl_tcp_rmem[1] = 43689; sysctl_tcp_rmem[2] = 2 * 43689; } printk(KERN_INFO "TCP: Hash tables configured " "(established %d bind %d)\n", tcp_ehash_size << 1, tcp_bhash_size); tcp_register_congestion_control(&tcp_reno); } EXPORT_SYMBOL(tcp_accept); EXPORT_SYMBOL(tcp_close); EXPORT_SYMBOL(tcp_destroy_sock); EXPORT_SYMBOL(tcp_disconnect); EXPORT_SYMBOL(tcp_getsockopt); EXPORT_SYMBOL(tcp_ioctl); EXPORT_SYMBOL(tcp_poll); EXPORT_SYMBOL(tcp_read_sock); EXPORT_SYMBOL(tcp_recvmsg); EXPORT_SYMBOL(tcp_sendmsg); EXPORT_SYMBOL(tcp_sendpage); EXPORT_SYMBOL(tcp_setsockopt); EXPORT_SYMBOL(tcp_shutdown); EXPORT_SYMBOL(tcp_statistics); EXPORT_SYMBOL(tcp_timewait_cachep);