/** * @file * Transmission Control Protocol for IP * * This file contains common functions for the TCP implementation, such as functinos * for manipulating the data structures and the TCP timer functions. TCP functions * related to input and output is found in tcp_in.c and tcp_out.c respectively. * */ /* * Copyright (c) 2001-2004 Swedish Institute of Computer Science. * All rights reserved. * * Redistribution and use in source and binary forms, with or without modification, * are permitted provided that the following conditions are met: * * 1. Redistributions of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation * and/or other materials provided with the distribution. * 3. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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. * * This file is part of the lwIP TCP/IP stack. * * Author: Adam Dunkels * */ #include "lwip/opt.h" #if LWIP_TCP /* don't build if not configured for use in lwipopts.h */ #include "lwip/def.h" #include "lwip/mem.h" #include "lwip/memp.h" #include "lwip/snmp.h" #include "lwip/tcp.h" #include "lwip/tcp_impl.h" #include "lwip/debug.h" #include "lwip/stats.h" #include const char * const tcp_state_str[] = { "CLOSED", "LISTEN", "SYN_SENT", "SYN_RCVD", "ESTABLISHED", "FIN_WAIT_1", "FIN_WAIT_2", "CLOSE_WAIT", "CLOSING", "LAST_ACK", "TIME_WAIT" }; /* Incremented every coarse grained timer shot (typically every 500 ms). */ u32_t tcp_ticks; const u8_t tcp_backoff[13] = { 1, 2, 3, 4, 5, 6, 7, 7, 7, 7, 7, 7, 7}; /* Times per slowtmr hits */ const u8_t tcp_persist_backoff[7] = { 3, 6, 12, 24, 48, 96, 120 }; /* The TCP PCB lists. */ /** List of all TCP PCBs bound but not yet (connected || listening) */ struct tcp_pcb *tcp_bound_pcbs; /** List of all TCP PCBs in LISTEN state */ union tcp_listen_pcbs_t tcp_listen_pcbs; /** List of all TCP PCBs that are in a state in which * they accept or send data. */ struct tcp_pcb *tcp_active_pcbs; /** List of all TCP PCBs in TIME-WAIT state */ struct tcp_pcb *tcp_tw_pcbs; #define NUM_TCP_PCB_LISTS 4 #define NUM_TCP_PCB_LISTS_NO_TIME_WAIT 3 /** An array with all (non-temporary) PCB lists, mainly used for smaller code size */ struct tcp_pcb ** const tcp_pcb_lists[] = {&tcp_listen_pcbs.pcbs, &tcp_bound_pcbs, &tcp_active_pcbs, &tcp_tw_pcbs}; /** Only used for temporary storage. */ struct tcp_pcb *tcp_tmp_pcb; /** Timer counter to handle calling slow-timer from tcp_tmr() */ static u8_t tcp_timer; static u16_t tcp_new_port(void);//����µ�tcp���ض˿� /** * Called periodically to dispatch TCP timers. * */ void tcp_tmr(void) { /* Call tcp_fasttmr() every 250 ms */ tcp_fasttmr(); if (++tcp_timer & 1) { /* Call tcp_tmr() every 500 ms, i.e., every other timer tcp_tmr() is called. */ tcp_slowtmr(); } } /** * Closes the TX side of a connection held by the PCB. * For tcp_close(), a RST is sent if the application didn't receive all data * (tcp_recved() not called for all data passed to recv callback). * * Listening pcbs are freed and may not be referenced any more. * Connection pcbs are freed if not yet connected and may not be referenced * any more. If a connection is established (at least SYN received or in * a closing state), the connection is closed, and put in a closing state. * The pcb is then automatically freed in tcp_slowtmr(). It is therefore * unsafe to reference it. * * @param pcb the tcp_pcb to close * @return ERR_OK if connection has been closed * another err_t if closing failed and pcb is not freed */ static err_t tcp_close_shutdown(struct tcp_pcb *pcb, u8_t rst_on_unacked_data) { err_t err; if (rst_on_unacked_data && (pcb->state != LISTEN)) { if ((pcb->refused_data != NULL) || (pcb->rcv_wnd != TCP_WND)) { /* Not all data received by application, send RST to tell the remote side about this. */ LWIP_ASSERT("pcb->flags & TF_RXCLOSED", pcb->flags & TF_RXCLOSED); /* don't call tcp_abort here: we must not deallocate the pcb since that might not be expected when calling tcp_close */ tcp_rst(pcb->snd_nxt, pcb->rcv_nxt, &pcb->local_ip, &pcb->remote_ip, pcb->local_port, pcb->remote_port); tcp_pcb_purge(pcb); /* TODO: to which state do we move now? */ /* move to TIME_WAIT since we close actively */ TCP_RMV(&tcp_active_pcbs, pcb); pcb->state = TIME_WAIT; TCP_REG(&tcp_tw_pcbs, pcb); return ERR_OK; } } switch (pcb->state) { case CLOSED: /* Closing a pcb in the CLOSED state might seem erroneous, * however, it is in this state once allocated and as yet unused * and the user needs some way to free it should the need arise. * Calling tcp_close() with a pcb that has already been closed, (i.e. twice) * or for a pcb that has been used and then entered the CLOSED state * is erroneous, but this should never happen as the pcb has in those cases * been freed, and so any remaining handles are bogus. */ /*��CLOSED״̬�¹ر�һ��pcb�ƺ��Ǵ���ģ� *������ˣ�һ�������״̬�·����˶��һ�û��ʹ��,�û���ҪһЩ�취���ͷ��� *����һ���Ѿ����رյ�pcb��tcp_close(),(��2��)����һ���Ѿ���ʹ����֮�󣬽���CLOSE״̬�Ǵ���� *������Щ����±��ͷŵ�pcb�Dz�����ڵ�,��ˣ��κ�ʣ��ľ���Ǽٵ� */ err = ERR_OK;//�趨����ֵ if (pcb->local_port != 0) { TCP_RMV(&tcp_bound_pcbs, pcb); } memp_free(MEMP_TCP_PCB, pcb);//��MEMP_TCP_PCB�ڴ���趨�ͷŵ���pcb��Ӧ�ĵ�Ԫֵ,�ͷ��ڴ� pcb = NULL; break; case LISTEN: err = ERR_OK; tcp_pcb_remove(&tcp_listen_pcbs.pcbs, pcb);//�Ӽ����PCB�б���ɾ���Ӧ��pcb memp_free(MEMP_TCP_PCB_LISTEN, pcb);//��MEMP_TCP_PCB_LISTEN�ڴ�����趨�ͷŵ�pcb��Ԫֵ ,�ͷ��ڴ� pcb = NULL; break; case SYN_SENT: err = ERR_OK; tcp_pcb_remove(&tcp_active_pcbs, pcb); memp_free(MEMP_TCP_PCB, pcb); pcb = NULL; snmp_inc_tcpattemptfails(); break; case SYN_RCVD: err = tcp_send_fin(pcb);//���������ر�FIN���ֱ��� if (err == ERR_OK) { snmp_inc_tcpattemptfails(); pcb->state = FIN_WAIT_1;//ת��FIN_WAIT_1״̬ } break; case ESTABLISHED: err = tcp_send_fin(pcb); if (err == ERR_OK) { snmp_inc_tcpestabresets(); pcb->state = FIN_WAIT_1; } break; case CLOSE_WAIT: err = tcp_send_fin(pcb); if (err == ERR_OK) { snmp_inc_tcpestabresets(); pcb->state = LAST_ACK;//����LAST_ACK�ȴ�ACK��ʱ } break; default: /* Has already been closed, do nothing. */ err = ERR_OK; pcb = NULL; break; } if (pcb != NULL && err == ERR_OK) { /* To ensure all data has been sent when tcp_close returns, we have to make sure tcp_output doesn't fail. Since we don't really have to ensure all data has been sent when tcp_close returns (unsent data is sent from tcp timer functions, also), we don't care for the return value of tcp_output for now. */ /* @todo: When implementing SO_LINGER, this must be changed somehow: If SOF_LINGER is set, the data should be sent and acked before close returns. This can only be valid for sequential APIs, not for the raw API. */ tcp_output(pcb);//���ú����Ϳ��ƿ������ʣ��ı��ģ�����FIN���ֱ��Ķ� } return err; } /** * Closes the connection held by the PCB. * * Listening pcbs are freed and may not be referenced any more. * Connection pcbs are freed if not yet connected and may not be referenced * any more. If a connection is established (at least SYN received or in * a closing state), the connection is closed, and put in a closing state. * The pcb is then automatically freed in tcp_slowtmr(). It is therefore * unsafe to reference it (unless an error is returned). * * @param pcb the tcp_pcb to close * @return ERR_OK if connection has been closed * another err_t if closing failed and pcb is not freed */ /* *ͨ��PCB�ر��������� *�����е�pcbӦ�ñ��ͷŵģ�Ҳ����ԶҲ���ᱻʹ���� *���û�����ӻ�����Ҳû�б�����,���ӵ�pcbӦ�ñ��ͷŵ� *���һ�����ӱ�����(����SYN�Ѿ������ջ�����һ���ر��е�״̬) *���ӱ��ر��ˣ�����������һ�����ڹرյ�״̬ *pcb�Զ���tcp_slowtmr()�ͷ�,�����������Dz���ȫ�� */ err_t tcp_close(struct tcp_pcb *pcb) { #if TCP_DEBUG //TCP debug��Ϣ����ӡpcb��״̬ LWIP_DEBUGF(TCP_DEBUG, ("tcp_close: closing in ")); tcp_debug_print_state(pcb->state); #endif /* TCP_DEBUG */ if (pcb->state != LISTEN) { /* Set a flag not to receive any more data... */ pcb->flags |= TF_RXCLOSED; } /* ... and close */ return tcp_close_shutdown(pcb, 1); } /** * Causes all or part of a full-duplex connection of this PCB to be shut down. * This doesn't deallocate the PCB! * * @param pcb PCB to shutdown * @param shut_rx shut down receive side if this is != 0 * @param shut_tx shut down send side if this is != 0 * @return ERR_OK if shutdown succeeded (or the PCB has already been shut down) * another err_t on error. */ err_t tcp_shutdown(struct tcp_pcb *pcb, int shut_rx, int shut_tx) { if (pcb->state == LISTEN) { return ERR_CONN; } if (shut_rx) { /* shut down the receive side: free buffered data... */ if (pcb->refused_data != NULL) { pbuf_free(pcb->refused_data); pcb->refused_data = NULL; } /* ... and set a flag not to receive any more data */ pcb->flags |= TF_RXCLOSED; } if (shut_tx) { /* This can't happen twice since if it succeeds, the pcb's state is changed. Only close in these states as the others directly deallocate the PCB */ switch (pcb->state) { case SYN_RCVD: case ESTABLISHED: case CLOSE_WAIT: return tcp_close_shutdown(pcb, 0); default: /* don't shut down other states */ break; } } /* @todo: return another err_t if not in correct state or already shut? */ return ERR_OK; } /** * Abandons a connection and optionally sends a RST to the remote * host. Deletes the local protocol control block. This is done when * a connection is killed because of shortage of memory. * * @param pcb the tcp_pcb to abort * @param reset boolean to indicate whether a reset should be sent */ void tcp_abandon(struct tcp_pcb *pcb, int reset) { u32_t seqno, ackno; u16_t remote_port, local_port; ip_addr_t remote_ip, local_ip; #if LWIP_CALLBACK_API tcp_err_fn errf; #endif /* LWIP_CALLBACK_API */ void *errf_arg; /* pcb->state LISTEN not allowed here */ LWIP_ASSERT("don't call tcp_abort/tcp_abandon for listen-pcbs", pcb->state != LISTEN); /* Figure out on which TCP PCB list we are, and remove us. If we are in an active state, call the receive function associated with the PCB with a NULL argument, and send an RST to the remote end. */ if (pcb->state == TIME_WAIT) { tcp_pcb_remove(&tcp_tw_pcbs, pcb); memp_free(MEMP_TCP_PCB, pcb); } else { seqno = pcb->snd_nxt; ackno = pcb->rcv_nxt; ip_addr_copy(local_ip, pcb->local_ip); ip_addr_copy(remote_ip, pcb->remote_ip); local_port = pcb->local_port; remote_port = pcb->remote_port; #if LWIP_CALLBACK_API errf = pcb->errf; #endif /* LWIP_CALLBACK_API */ errf_arg = pcb->callback_arg; tcp_pcb_remove(&tcp_active_pcbs, pcb); if (pcb->unacked != NULL) { tcp_segs_free(pcb->unacked); } if (pcb->unsent != NULL) { tcp_segs_free(pcb->unsent); } #if TCP_QUEUE_OOSEQ if (pcb->ooseq != NULL) { tcp_segs_free(pcb->ooseq); } #endif /* TCP_QUEUE_OOSEQ */ if (reset) { LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_abandon: sending RST\n")); tcp_rst(seqno, ackno, &local_ip, &remote_ip, local_port, remote_port); } TCP_EVENT_ERR(errf, errf_arg, ERR_ABRT); memp_free(MEMP_TCP_PCB, pcb); } } /** * Aborts the connection by sending a RST (reset) segment to the remote * host. The pcb is deallocated. This function never fails. * * ATTENTION: When calling this from one of the TCP callbacks, make * sure you always return ERR_ABRT (and never return ERR_ABRT otherwise * or you will risk accessing deallocated memory or memory leaks! * * @param pcb the tcp pcb to abort */ void tcp_abort(struct tcp_pcb *pcb) { tcp_abandon(pcb, 1); } /** * Binds the connection to a local portnumber and IP address. If the * IP address is not given (i.e., ipaddr == NULL), the IP address of * the outgoing network interface is used instead. * * @param pcb the tcp_pcb to bind (no check is done whether this pcb is * already bound!) * @param ipaddr the local ip address to bind to (use IP_ADDR_ANY to bind * to any local address * @param port the local port to bind to * @return ERR_USE if the port is already in use * ERR_OK if bound */ err_t tcp_bind(struct tcp_pcb *pcb, ip_addr_t *ipaddr, u16_t port) { int i; int max_pcb_list = NUM_TCP_PCB_LISTS; struct tcp_pcb *cpcb; LWIP_ERROR("tcp_bind: can only bind in state CLOSED", pcb->state == CLOSED, return ERR_ISCONN); #if SO_REUSE /* Unless the REUSEADDR flag is set, we have to check the pcbs in TIME-WAIT state, also. We do not dump TIME_WAIT pcb's; they can still be matched by incoming packets using both local and remote IP addresses and ports to distinguish. */ if ((pcb->so_options & SOF_REUSEADDR) != 0) { max_pcb_list = NUM_TCP_PCB_LISTS_NO_TIME_WAIT; } #endif /* SO_REUSE */ if (port == 0) { port = tcp_new_port(); } /* Check if the address already is in use (on all lists) */ for (i = 0; i < max_pcb_list; i++) { for(cpcb = *tcp_pcb_lists[i]; cpcb != NULL; cpcb = cpcb->next) { if (cpcb->local_port == port) { #if SO_REUSE /* Omit checking for the same port if both pcbs have REUSEADDR set. For SO_REUSEADDR, the duplicate-check for a 5-tuple is done in tcp_connect. */ if (((pcb->so_options & SOF_REUSEADDR) == 0) || ((cpcb->so_options & SOF_REUSEADDR) == 0)) #endif /* SO_REUSE */ { if (ip_addr_isany(&(cpcb->local_ip)) || ip_addr_isany(ipaddr) || ip_addr_cmp(&(cpcb->local_ip), ipaddr)) { //os_printf("Address in use\n"); return ERR_USE; } } } } } if (!ip_addr_isany(ipaddr)) { pcb->local_ip = *ipaddr; } pcb->local_port = port; TCP_REG(&tcp_bound_pcbs, pcb); LWIP_DEBUGF(TCP_DEBUG, ("tcp_bind: bind to port %"U16_F"\n", port)); return ERR_OK; } #if LWIP_CALLBACK_API /** * Default accept callback if no accept callback is specified by the user. */ static err_t tcp_accept_null(void *arg, struct tcp_pcb *pcb, err_t err) { LWIP_UNUSED_ARG(arg); LWIP_UNUSED_ARG(pcb); LWIP_UNUSED_ARG(err); return ERR_ABRT; } #endif /* LWIP_CALLBACK_API */ /** * Set the state of the connection to be LISTEN, which means that it * is able to accept incoming connections. The protocol control block * is reallocated in order to consume less memory. Setting the * connection to LISTEN is an irreversible process. *��ij���󶨵Ŀ��ƿ���Ϊ����״̬ * @param pcb the original tcp_pcb �����Ŀ��ƿ���� * @param backlog the incoming connections queue limit * @return tcp_pcb used for listening, consumes less memory.ָ������״̬�Ŀ��ƿ� * * @note The original tcp_pcb is freed. This function therefore has to be * called like this: * tpcb = tcp_listen(tpcb); */ struct tcp_pcb * tcp_listen_with_backlog(struct tcp_pcb *pcb, u8_t backlog) { struct tcp_pcb_listen *lpcb; LWIP_UNUSED_ARG(backlog); LWIP_ERROR("tcp_listen: pcb already connected", pcb->state == CLOSED, return NULL); /* already listening? */ if (pcb->state == LISTEN) { return pcb; } #if SO_REUSE if ((pcb->so_options & SOF_REUSEADDR) != 0) { /* Since SOF_REUSEADDR allows reusing a local address before the pcb's usage is declared (listen-/connection-pcb), we have to make sure now that this port is only used once for every local IP. */ for(lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) { if (lpcb->local_port == pcb->local_port) { if (ip_addr_cmp(&lpcb->local_ip, &pcb->local_ip)) { /* this address/port is already used */ return NULL; } } } } #endif /* SO_REUSE */ lpcb = (struct tcp_pcb_listen *)memp_malloc(MEMP_TCP_PCB_LISTEN);//�����ڴ�ؿռ� if (lpcb == NULL) { return NULL; } lpcb->callback_arg = pcb->callback_arg; lpcb->local_port = pcb->local_port; lpcb->state = LISTEN; lpcb->prio = pcb->prio; lpcb->so_options = pcb->so_options; lpcb->so_options |= SOF_ACCEPTCONN; lpcb->ttl = pcb->ttl; lpcb->tos = pcb->tos; ip_addr_copy(lpcb->local_ip, pcb->local_ip); if (pcb->local_port != 0) { TCP_RMV(&tcp_bound_pcbs, pcb); } memp_free(MEMP_TCP_PCB, pcb); #if LWIP_CALLBACK_API lpcb->accept = tcp_accept_null;//���ܿͻ������ӵ�Ĭ�ϻص����� #endif /* LWIP_CALLBACK_API */ #if TCP_LISTEN_BACKLOG lpcb->accepts_pending = 0; lpcb->backlog = (backlog ? backlog : 1); #endif /* TCP_LISTEN_BACKLOG */ TCP_REG(&tcp_listen_pcbs.pcbs, (struct tcp_pcb *)lpcb);//���ƿ����tcp_listen_pcbs�����ײ� return (struct tcp_pcb *)lpcb; } /** * Update the state that tracks the available window space to advertise. * * Returns how much extra window would be advertised if we sent an * update now. */ u32_t tcp_update_rcv_ann_wnd(struct tcp_pcb *pcb) { u32_t new_right_edge = pcb->rcv_nxt + pcb->rcv_wnd; if (TCP_SEQ_GEQ(new_right_edge, pcb->rcv_ann_right_edge + LWIP_MIN((TCP_WND / 2), pcb->mss))) { /* we can advertise more window */ pcb->rcv_ann_wnd = pcb->rcv_wnd; return new_right_edge - pcb->rcv_ann_right_edge; } else { if (TCP_SEQ_GT(pcb->rcv_nxt, pcb->rcv_ann_right_edge)) { /* Can happen due to other end sending out of advertised window, * but within actual available (but not yet advertised) window */ pcb->rcv_ann_wnd = 0; } else { /* keep the right edge of window constant */ u32_t new_rcv_ann_wnd = pcb->rcv_ann_right_edge - pcb->rcv_nxt; LWIP_ASSERT("new_rcv_ann_wnd <= 0xffff", new_rcv_ann_wnd <= 0xffff); pcb->rcv_ann_wnd = (u16_t)new_rcv_ann_wnd; } return 0; } } /** * This function should be called by the application when it has * processed the data. The purpose is to advertise a larger window * when the data has been processed. *Ӧ�ó�����ݴ�����Ϻ�֪ͨ�ں˸��½��մ��� * @param pcb the tcp_pcb for which data is read * @param len the amount of bytes that have been read by the application */ void tcp_recved(struct tcp_pcb *pcb, u16_t len) { int wnd_inflation; LWIP_ASSERT("tcp_recved: len would wrap rcv_wnd\n", len <= 0xffff - pcb->rcv_wnd ); pcb->rcv_wnd += len; if (pcb->rcv_wnd > TCP_WND) { pcb->rcv_wnd = TCP_WND; } wnd_inflation = tcp_update_rcv_ann_wnd(pcb); /* If the change in the right edge of window is significant (default * watermark is TCP_WND/4), then send an explicit update now. * Otherwise wait for a packet to be sent in the normal course of * events (or more window to be available later) */ if (wnd_inflation >= TCP_WND_UPDATE_THRESHOLD) { tcp_ack_now(pcb); tcp_output(pcb); } LWIP_DEBUGF(TCP_DEBUG, ("tcp_recved: recveived %"U16_F" bytes, wnd %"U16_F" (%"U16_F").\n", len, pcb->rcv_wnd, TCP_WND - pcb->rcv_wnd)); } /** * A nastly hack featuring 'goto' statements that allocates a * new TCP local port. * * @return a new (free) local TCP port number */ static u16_t tcp_new_port(void) { int i; struct tcp_pcb *pcb; #ifndef TCP_LOCAL_PORT_RANGE_START #define TCP_LOCAL_PORT_RANGE_START 4096 #define TCP_LOCAL_PORT_RANGE_END 0x7fff #endif static u16_t port = TCP_LOCAL_PORT_RANGE_START; again: if (++port >= TCP_LOCAL_PORT_RANGE_END) { port = TCP_LOCAL_PORT_RANGE_START; } /* Check all PCB lists. */ for (i = 0; i < NUM_TCP_PCB_LISTS; i++) { for(pcb = *tcp_pcb_lists[i]; pcb != NULL; pcb = pcb->next) { if (pcb->local_port == port) { goto again; } } } return port; } /** * Connects to another host. The function given as the "connected" * argument will be called when the connection has been established. *�����������һ��SYN���ֱ��� * @param pcb the tcp_pcb used to establish the connection �����Ŀ��ƿ���� * @param ipaddr the remote ip address to connect to ������IP��ַ * @param port the remote tcp port to connect to �������˿ں� * @param connected callback function to call when connected (or on error) * @return ERR_VAL if invalid arguments are given * ERR_OK if connect request has been sent * other err_t values if connect request couldn't be sent */ err_t tcp_connect(struct tcp_pcb *pcb, ip_addr_t *ipaddr, u16_t port, tcp_connected_fn connected) { err_t ret; u32_t iss; u16_t old_local_port; LWIP_ERROR("tcp_connect: can only connected from state CLOSED", pcb->state == CLOSED, return ERR_ISCONN); LWIP_DEBUGF(TCP_DEBUG, ("tcp_connect to port %"U16_F"\n", port)); if (ipaddr != NULL) { pcb->remote_ip = *ipaddr;//������IP��ַ��Ч�������Ӽ�¼�м�¼��IP��ַ�����򷵻ش��� } else { return ERR_VAL; } pcb->remote_port = port;//��¼�������˿�(Ŀ�Ķ˿�) /* check if we have a route to the remote host */ if (ip_addr_isany(&(pcb->local_ip))) { /* no local IP address set, yet. */ struct netif *netif = ip_route(&(pcb->remote_ip)); if (netif == NULL) { /* Don't even try to send a SYN packet if we have no route since that will fail. */ return ERR_RTE; } /* Use the netif's IP address as local address. */ ip_addr_copy(pcb->local_ip, netif->ip_addr); } old_local_port = pcb->local_port; if (pcb->local_port == 0) { pcb->local_port = tcp_new_port(); } #if SO_REUSE if ((pcb->so_options & SOF_REUSEADDR) != 0) { /* Since SOF_REUSEADDR allows reusing a local address, we have to make sure now that the 5-tuple is unique. */ struct tcp_pcb *cpcb; int i; /* Don't check listen- and bound-PCBs, check active- and TIME-WAIT PCBs. */ for (i = 2; i < NUM_TCP_PCB_LISTS; i++) { for(cpcb = *tcp_pcb_lists[i]; cpcb != NULL; cpcb = cpcb->next) { if ((cpcb->local_port == pcb->local_port) && (cpcb->remote_port == port) && ip_addr_cmp(&cpcb->local_ip, &pcb->local_ip) && ip_addr_cmp(&cpcb->remote_ip, ipaddr)) { /* linux returns EISCONN here, but ERR_USE should be OK for us */ return ERR_USE; } } } } #endif /* SO_REUSE */ iss = tcp_next_iss();//��ʼ����� pcb->rcv_nxt = 0;//���÷��ʹ��ڵĸ����ֶ� pcb->snd_nxt = iss; pcb->lastack = iss - 1; pcb->snd_lbb = iss - 1; pcb->rcv_wnd = TCP_WND;//����Ĭ�Ͻ��մ��ڸ����ֶ�ֵ pcb->rcv_ann_wnd = TCP_WND; pcb->rcv_ann_right_edge = pcb->rcv_nxt; pcb->snd_wnd = TCP_WND; /* As initial send MSS, we use TCP_MSS but limit it to 536. The send MSS is updated when an MSS option is received. */ pcb->mss = (TCP_MSS > 536) ? 536 : TCP_MSS;//��ʼ������Ķδ�С #if TCP_CALCULATE_EFF_SEND_MSS pcb->mss = tcp_eff_send_mss(pcb->mss, ipaddr); #endif /* TCP_CALCULATE_EFF_SEND_MSS */ pcb->cwnd = 1;//��ʼ������� pcb->ssthresh = pcb->mss * 10; #if LWIP_CALLBACK_API pcb->connected = connected;//ע��connected�ص����� #else /* LWIP_CALLBACK_API */ LWIP_UNUSED_ARG(connected); #endif /* LWIP_CALLBACK_API */ /* Send a SYN together with the MSS option. */ ret = tcp_enqueue_flags(pcb, TCP_SYN); if (ret == ERR_OK) { /* SYN segment was enqueued, changed the pcbs state now ���ƿ�����ΪSYN_SENT ״̬*/ pcb->state = SYN_SENT; if (old_local_port != 0) { TCP_RMV(&tcp_bound_pcbs, pcb); } TCP_REG(&tcp_active_pcbs, pcb); snmp_inc_tcpactiveopens(); tcp_output(pcb);//�����ƿ������ӵı��ķ��ͳ�ȥ } return ret; } /** * Called every 500 ms and implements the retransmission timer and the timer that * removes PCBs that have been in TIME-WAIT for enough time. It also increments * various timers such as the inactivity timer in each PCB. * * Automatically called from tcp_tmr(). */ void tcp_slowtmr(void) { struct tcp_pcb *pcb, *prev; u16_t eff_wnd; u8_t pcb_remove; /* flag if a PCB should be removed */ u8_t pcb_reset; /* flag if a RST should be sent when removing */ err_t err; err = ERR_OK; ++tcp_ticks; /* Steps through all of the active PCBs. */ prev = NULL; pcb = tcp_active_pcbs; if (pcb == NULL) { LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: no active pcbs\n")); } while (pcb != NULL) { LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: processing active pcb\n")); LWIP_ASSERT("tcp_slowtmr: active pcb->state != CLOSED\n", pcb->state != CLOSED); LWIP_ASSERT("tcp_slowtmr: active pcb->state != LISTEN\n", pcb->state != LISTEN); LWIP_ASSERT("tcp_slowtmr: active pcb->state != TIME-WAIT\n", pcb->state != TIME_WAIT); pcb_remove = 0; pcb_reset = 0; if (pcb->state == SYN_SENT && pcb->nrtx == TCP_SYNMAXRTX) { ++pcb_remove; LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: max SYN retries reached\n")); } else if (pcb->nrtx == TCP_MAXRTX) { ++pcb_remove; LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: max DATA retries reached\n")); } else { if (pcb->persist_backoff > 0) { /* If snd_wnd is zero, use persist timer to send 1 byte probes * instead of using the standard retransmission mechanism. */ pcb->persist_cnt++; if (pcb->persist_cnt >= tcp_persist_backoff[pcb->persist_backoff-1]) { pcb->persist_cnt = 0; if (pcb->persist_backoff < sizeof(tcp_persist_backoff)) { pcb->persist_backoff++; } tcp_zero_window_probe(pcb); } } else { /* Increase the retransmission timer if it is running */ if(pcb->rtime >= 0) ++pcb->rtime; if (pcb->unacked != NULL && pcb->rtime >= pcb->rto) { /* Time for a retransmission. */ LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_slowtmr: rtime %"S16_F " pcb->rto %"S16_F"\n", pcb->rtime, pcb->rto)); /* Double retransmission time-out unless we are trying to * connect to somebody (i.e., we are in SYN_SENT). */ if (pcb->state != SYN_SENT) { pcb->rto = ((pcb->sa >> 3) + pcb->sv) << tcp_backoff[pcb->nrtx]; // if (pcb->rto >= TCP_MAXRTO) // pcb->rto >>= 1; } /* Reset the retransmission timer. */ pcb->rtime = 0; /* Reduce congestion window and ssthresh. */ eff_wnd = LWIP_MIN(pcb->cwnd, pcb->snd_wnd); pcb->ssthresh = eff_wnd >> 1; if (pcb->ssthresh < (pcb->mss << 1)) { pcb->ssthresh = (pcb->mss << 1); } pcb->cwnd = pcb->mss; LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_slowtmr: cwnd %"U16_F " ssthresh %"U16_F"\n", pcb->cwnd, pcb->ssthresh)); /* The following needs to be called AFTER cwnd is set to one mss - STJ */ tcp_rexmit_rto(pcb); } } } /* Check if this PCB has stayed too long in FIN-WAIT-2 */ if (pcb->state == FIN_WAIT_2) { if ((u32_t)(tcp_ticks - pcb->tmr) > TCP_FIN_WAIT_TIMEOUT / TCP_SLOW_INTERVAL) { ++pcb_remove; LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: removing pcb stuck in FIN-WAIT-2\n")); } } /* Check if KEEPALIVE should be sent */ if((pcb->so_options & SOF_KEEPALIVE) && ((pcb->state == ESTABLISHED) || (pcb->state == CLOSE_WAIT))) { #if LWIP_TCP_KEEPALIVE if((u32_t)(tcp_ticks - pcb->tmr) > (pcb->keep_idle + (pcb->keep_cnt*pcb->keep_intvl)) / TCP_SLOW_INTERVAL) #else if((u32_t)(tcp_ticks - pcb->tmr) > (pcb->keep_idle + TCP_MAXIDLE) / TCP_SLOW_INTERVAL) #endif /* LWIP_TCP_KEEPALIVE */ { LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: KEEPALIVE timeout. Aborting connection to %"U16_F".%"U16_F".%"U16_F".%"U16_F".\n", ip4_addr1_16(&pcb->remote_ip), ip4_addr2_16(&pcb->remote_ip), ip4_addr3_16(&pcb->remote_ip), ip4_addr4_16(&pcb->remote_ip))); ++pcb_remove; ++pcb_reset; } #if LWIP_TCP_KEEPALIVE else if((u32_t)(tcp_ticks - pcb->tmr) > (pcb->keep_idle + pcb->keep_cnt_sent * pcb->keep_intvl) / TCP_SLOW_INTERVAL) #else else if((u32_t)(tcp_ticks - pcb->tmr) > (pcb->keep_idle + pcb->keep_cnt_sent * TCP_KEEPINTVL_DEFAULT) / TCP_SLOW_INTERVAL) #endif /* LWIP_TCP_KEEPALIVE */ { tcp_keepalive(pcb); pcb->keep_cnt_sent++; } } /* If this PCB has queued out of sequence data, but has been inactive for too long, will drop the data (it will eventually be retransmitted). */ #if TCP_QUEUE_OOSEQ if (pcb->ooseq != NULL && (u32_t)tcp_ticks - pcb->tmr >= pcb->rto * TCP_OOSEQ_TIMEOUT) { tcp_segs_free(pcb->ooseq); pcb->ooseq = NULL; LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_slowtmr: dropping OOSEQ queued data\n")); } #endif /* TCP_QUEUE_OOSEQ */ /* Check if this PCB has stayed too long in SYN-RCVD */ if (pcb->state == SYN_RCVD) { if ((u32_t)(tcp_ticks - pcb->tmr) > TCP_SYN_RCVD_TIMEOUT / TCP_SLOW_INTERVAL) { ++pcb_remove; LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: removing pcb stuck in SYN-RCVD\n")); } } /* Check if this PCB has stayed too long in LAST-ACK */ if (pcb->state == LAST_ACK) { if ((u32_t)(tcp_ticks - pcb->tmr) > 2 * TCP_MSL / TCP_SLOW_INTERVAL) { ++pcb_remove; LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: removing pcb stuck in LAST-ACK\n")); } } /* If the PCB should be removed, do it. */ if (pcb_remove) { struct tcp_pcb *pcb2; tcp_pcb_purge(pcb); /* Remove PCB from tcp_active_pcbs list. */ if (prev != NULL) { LWIP_ASSERT("tcp_slowtmr: middle tcp != tcp_active_pcbs", pcb != tcp_active_pcbs); prev->next = pcb->next; } else { /* This PCB was the first. */ LWIP_ASSERT("tcp_slowtmr: first pcb == tcp_active_pcbs", tcp_active_pcbs == pcb); tcp_active_pcbs = pcb->next; } if (pcb_reset) { tcp_rst(pcb->snd_nxt, pcb->rcv_nxt, &pcb->local_ip, &pcb->remote_ip, pcb->local_port, pcb->remote_port); } TCP_EVENT_ERR(pcb->errf, pcb->callback_arg, ERR_ABRT); pcb2 = pcb; pcb = pcb->next; memp_free(MEMP_TCP_PCB, pcb2); } else { /* get the 'next' element now and work with 'prev' below (in case of abort) */ prev = pcb; pcb = pcb->next; /* We check if we should poll the connection. */ ++prev->polltmr; if (prev->polltmr >= prev->pollinterval) { prev->polltmr = 0; LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: polling application\n")); TCP_EVENT_POLL(prev, err); /* if err == ERR_ABRT, 'prev' is already deallocated */ if (err == ERR_OK) { tcp_output(prev); } } } } /* Steps through all of the TIME-WAIT PCBs. */ prev = NULL; pcb = tcp_tw_pcbs; while (pcb != NULL) { LWIP_ASSERT("tcp_slowtmr: TIME-WAIT pcb->state == TIME-WAIT", pcb->state == TIME_WAIT); pcb_remove = 0; /* Check if this PCB has stayed long enough in TIME-WAIT */ if ((u32_t)(tcp_ticks - pcb->tmr) > 2 * TCP_MSL / TCP_SLOW_INTERVAL) { ++pcb_remove; } /* If the PCB should be removed, do it. */ if (pcb_remove) { struct tcp_pcb *pcb2; tcp_pcb_purge(pcb); /* Remove PCB from tcp_tw_pcbs list. */ if (prev != NULL) { LWIP_ASSERT("tcp_slowtmr: middle tcp != tcp_tw_pcbs", pcb != tcp_tw_pcbs); prev->next = pcb->next; } else { /* This PCB was the first. */ LWIP_ASSERT("tcp_slowtmr: first pcb == tcp_tw_pcbs", tcp_tw_pcbs == pcb); tcp_tw_pcbs = pcb->next; } pcb2 = pcb; pcb = pcb->next; memp_free(MEMP_TCP_PCB, pcb2); } else { prev = pcb; pcb = pcb->next; } } } /** * Is called every TCP_FAST_INTERVAL (250 ms) and process data previously * "refused" by upper layer (application) and sends delayed ACKs. * * Automatically called from tcp_tmr(). */ void tcp_fasttmr(void) { struct tcp_pcb *pcb = tcp_active_pcbs; while(pcb != NULL) { struct tcp_pcb *next = pcb->next; /* If there is data which was previously "refused" by upper layer */ if (pcb->refused_data != NULL) { /* Notify again application with data previously received. */ err_t err; LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_fasttmr: notify kept packet\n")); TCP_EVENT_RECV(pcb, pcb->refused_data, ERR_OK, err); if (err == ERR_OK) { pcb->refused_data = NULL; } else if (err == ERR_ABRT) { /* if err == ERR_ABRT, 'pcb' is already deallocated */ pcb = NULL; } } /* send delayed ACKs */ if (pcb && (pcb->flags & TF_ACK_DELAY)) { LWIP_DEBUGF(TCP_DEBUG, ("tcp_fasttmr: delayed ACK\n")); tcp_ack_now(pcb); tcp_output(pcb); pcb->flags &= ~(TF_ACK_DELAY | TF_ACK_NOW); } pcb = next; } } /** * Deallocates a list of TCP segments (tcp_seg structures). * * @param seg tcp_seg list of TCP segments to free */ void tcp_segs_free(struct tcp_seg *seg) { while (seg != NULL) { struct tcp_seg *next = seg->next; tcp_seg_free(seg); seg = next; } } /** * Frees a TCP segment (tcp_seg structure). * * @param seg single tcp_seg to free */ void tcp_seg_free(struct tcp_seg *seg) { if (seg != NULL) { if (seg->p != NULL) { pbuf_free(seg->p); #if TCP_DEBUG seg->p = NULL; #endif /* TCP_DEBUG */ } memp_free(MEMP_TCP_SEG, seg); } } /** * Sets the priority of a connection. * * @param pcb the tcp_pcb to manipulate * @param prio new priority */ void tcp_setprio(struct tcp_pcb *pcb, u8_t prio) { pcb->prio = prio; } #if TCP_QUEUE_OOSEQ /** * Returns a copy of the given TCP segment. * The pbuf and data are not copied, only the pointers * * @param seg the old tcp_seg * @return a copy of seg */ struct tcp_seg * tcp_seg_copy(struct tcp_seg *seg) { struct tcp_seg *cseg; cseg = (struct tcp_seg *)memp_malloc(MEMP_TCP_SEG); if (cseg == NULL) { return NULL; } SMEMCPY((u8_t *)cseg, (const u8_t *)seg, sizeof(struct tcp_seg)); pbuf_ref(cseg->p); return cseg; } #endif /* TCP_QUEUE_OOSEQ */ #if LWIP_CALLBACK_API /** * Default receive callback that is called if the user didn't register * a recv callback for the pcb. */ err_t tcp_recv_null(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err) { LWIP_UNUSED_ARG(arg); if (p != NULL) { tcp_recved(pcb, p->tot_len); pbuf_free(p); } else if (err == ERR_OK) { return tcp_close(pcb); } return ERR_OK; } #endif /* LWIP_CALLBACK_API */ /** * Kills the oldest active connection that has lower priority than prio. * * @param prio minimum priority */ static void ICACHE_FLASH_ATTR tcp_kill_prio(u8_t prio) { struct tcp_pcb *pcb, *inactive; u32_t inactivity; u8_t mprio; mprio = TCP_PRIO_MAX; /* We kill the oldest active connection that has lower priority than prio. */ inactivity = 0; inactive = NULL; for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) { if (pcb->prio <= prio && pcb->prio <= mprio && (u32_t)(tcp_ticks - pcb->tmr) >= inactivity) { inactivity = tcp_ticks - pcb->tmr; inactive = pcb; mprio = pcb->prio; } } if (inactive != NULL) { LWIP_DEBUGF(TCP_DEBUG, ("tcp_kill_prio: killing oldest PCB %p (%"S32_F")\n", (void *)inactive, inactivity)); tcp_abort(inactive); } } /** * Kills the oldest connection that is in TIME_WAIT state. * Called from tcp_alloc() if no more connections are available. */ static void ICACHE_FLASH_ATTR tcp_kill_timewait(void) { struct tcp_pcb *pcb, *inactive; u32_t inactivity; inactivity = 0; inactive = NULL; /* Go through the list of TIME_WAIT pcbs and get the oldest pcb. */ for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) { if ((u32_t)(tcp_ticks - pcb->tmr) >= inactivity) { inactivity = tcp_ticks - pcb->tmr; inactive = pcb; } } if (inactive != NULL) { LWIP_DEBUGF(TCP_DEBUG, ("tcp_kill_timewait: killing oldest TIME-WAIT PCB %p (%"S32_F")\n", (void *)inactive, inactivity)); tcp_abort(inactive); } } /** * Allocate a new tcp_pcb structure. *����һ��TCP���ƿ�ṹ������ʼ������ֶ� * @param prio priority for the new pcb �¿��ƿ�����ȼ� * @return a new tcp_pcb that initially is in state CLOSED ָ���¿��ƿ��ָ�� */ struct tcp_pcb * tcp_alloc(u8_t prio) { struct tcp_pcb *pcb; u32_t iss; pcb = (struct tcp_pcb *)memp_malloc(MEMP_TCP_PCB);//�����ڴ�ؿռ� if (pcb == NULL) { //os_printf("tcp_pcb memory is fail\n"); /* Try killing oldest connection in TIME-WAIT. */ LWIP_DEBUGF(TCP_DEBUG, ("tcp_alloc: killing off oldest TIME-WAIT connection\n")); tcp_kill_timewait(); /* Try to allocate a tcp_pcb again. */ pcb = (struct tcp_pcb *)memp_malloc(MEMP_TCP_PCB); if (pcb == NULL) { /* Try killing active connections with lower priority than the new one. */ LWIP_DEBUGF(TCP_DEBUG, ("tcp_alloc: killing connection with prio lower than %d\n", prio)); tcp_kill_prio(prio); /* Try to allocate a tcp_pcb again. */ pcb = (struct tcp_pcb *)memp_malloc(MEMP_TCP_PCB); if (pcb != NULL) { /* adjust err stats: memp_malloc failed twice before */ MEMP_STATS_DEC(err, MEMP_TCP_PCB); } } if (pcb != NULL) { /* adjust err stats: timewait PCB was freed above */ MEMP_STATS_DEC(err, MEMP_TCP_PCB); } } if (pcb != NULL) { memset(pcb, 0, sizeof(struct tcp_pcb)); //��0 pcb->prio = prio; //�������ȼ� pcb->snd_buf = TCP_SND_BUF; //��ʹ�õķ��ͻ������С pcb->snd_queuelen = 0; //��������ռ�õ�pbuf���� pcb->rcv_wnd = TCP_WND; //���մ��� pcb->rcv_ann_wnd = TCP_WND; //ͨ����մ��� pcb->tos = 0; //�������� pcb->ttl = TCP_TTL; //ttl�ֶ� /* As initial send MSS, we use TCP_MSS but limit it to 536. The send MSS is updated when an MSS option is received. */ pcb->mss = (TCP_MSS > 536) ? 536 : TCP_MSS; //��ʼ������Ķ� pcb->rto = 1000 / TCP_SLOW_INTERVAL; //��ʼ����ʱʱ�� pcb->sa = 0; //��ʼ����RTT��صIJ��� pcb->sv = 1000 / TCP_SLOW_INTERVAL; pcb->rtime = -1; pcb->cwnd = 1; //��ʼ������� iss = tcp_next_iss(); //��ó�ʼ���к� pcb->snd_wl2 = iss; //��ʼ�����ʹ��ڸ����ֶ� pcb->snd_nxt = iss; pcb->lastack = iss; pcb->snd_lbb = iss; pcb->tmr = tcp_ticks; //��¼���ƿ鴴��ϵͳʱ�� pcb->polltmr = 0; //����������¼���ʱ�� #if LWIP_CALLBACK_API pcb->recv = tcp_recv_null; //ע�������ݵ�Ĭ���ϲ㺯�� #endif /* LWIP_CALLBACK_API */ /* Init KEEPALIVE timer */ pcb->keep_idle = TCP_KEEPIDLE_DEFAULT; #if LWIP_TCP_KEEPALIVE pcb->keep_intvl = TCP_KEEPINTVL_DEFAULT; pcb->keep_cnt = TCP_KEEPCNT_DEFAULT; #endif /* LWIP_TCP_KEEPALIVE */ pcb->keep_cnt_sent = 0; //���ķ��ʹ��� } return pcb; } /** * Creates a new TCP protocol control block but doesn't place it on * any of the TCP PCB lists. * The pcb is not put on any list until binding using tcp_bind(). * * @internal: Maybe there should be a idle TCP PCB list where these * PCBs are put on. Port reservation using tcp_bind() is implemented but * allocated pcbs that are not bound can't be killed automatically if wanting * to allocate a pcb with higher prio (@see tcp_kill_prio()) * * @return a new tcp_pcb that initially is in state CLOSED */ struct tcp_pcb * tcp_new(void) { return tcp_alloc(TCP_PRIO_NORMAL); } /** * Used to specify the argument that should be passed callback * functions. *����ƿ��callback_arg�ֶ�ע���û���ݣ���tcp_recv�Ⱥ���ص�ʱ�� * ���ֶν���Ϊ����ݸ�������� * @param pcb tcp_pcb to set the callback argument * @param arg void pointer argument to pass to callback functions */ void tcp_arg(struct tcp_pcb *pcb, void *arg) { pcb->callback_arg = arg; } #if LWIP_CALLBACK_API /** * Used to specify the function that should be called when a TCP * connection receives data. *����ƿ��recv�ֶ�ע�ắ���յ����ʱ�ص� * @param pcb tcp_pcb to set the recv callback * @param recv callback function to call for this pcb when data is received */ void tcp_recv(struct tcp_pcb *pcb, tcp_recv_fn recv) { pcb->recv = recv; } /** * Used to specify the function that should be called when TCP data * has been successfully delivered to the remote host. *����ƿ�send �ֶ�ע�ắ����ݷ��ͳɹ���ص� * @param pcb tcp_pcb to set the sent callback * @param sent callback function to call for this pcb when data is successfully sent */ void tcp_sent(struct tcp_pcb *pcb, tcp_sent_fn sent) { pcb->sent = sent; } /** * Used to specify the function that should be called when a fatal error * has occured on the connection. *����ƿ�err �ֶ�ע�ắ�����������ص� * @param pcb tcp_pcb to set the err callback * @param err callback function to call for this pcb when a fatal error * has occured on the connection */ void tcp_err(struct tcp_pcb *pcb, tcp_err_fn err) { pcb->errf = err; } /** * Used for specifying the function that should be called when a * LISTENing connection has been connected to another host. *����ƿ��accept�ֶ�ע�ắ����������ʱ�ص� * @param pcb tcp_pcb to set the accept callback * @param accept callback function to call for this pcb when LISTENing * connection has been connected to another host */ void tcp_accept(struct tcp_pcb *pcb, tcp_accept_fn accept) { pcb->accept = accept; } #endif /* LWIP_CALLBACK_API */ /** * Used to specify the function that should be called periodically * from TCP. The interval is specified in terms of the TCP coarse * timer interval, which is called twice a second. *����ƿ��POLL�ֶ�ע�ắ��ú��������Ա����� */ void tcp_poll(struct tcp_pcb *pcb, tcp_poll_fn poll, u8_t interval) { #if LWIP_CALLBACK_API pcb->poll = poll; #else /* LWIP_CALLBACK_API */ LWIP_UNUSED_ARG(poll); #endif /* LWIP_CALLBACK_API */ pcb->pollinterval = interval; } /** * Purges a TCP PCB. Removes any buffered data and frees the buffer memory * (pcb->ooseq, pcb->unsent and pcb->unacked are freed). * * @param pcb tcp_pcb to purge. The pcb itself is not deallocated! */ void tcp_pcb_purge(struct tcp_pcb *pcb) { if (pcb->state != CLOSED && pcb->state != TIME_WAIT && pcb->state != LISTEN) { LWIP_DEBUGF(TCP_DEBUG, ("tcp_pcb_purge\n")); #if TCP_LISTEN_BACKLOG if (pcb->state == SYN_RCVD) { /* Need to find the corresponding listen_pcb and decrease its accepts_pending */ struct tcp_pcb_listen *lpcb; LWIP_ASSERT("tcp_pcb_purge: pcb->state == SYN_RCVD but tcp_listen_pcbs is NULL", tcp_listen_pcbs.listen_pcbs != NULL); for (lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) { if ((lpcb->local_port == pcb->local_port) && (ip_addr_isany(&lpcb->local_ip) || ip_addr_cmp(&pcb->local_ip, &lpcb->local_ip))) { /* port and address of the listen pcb match the timed-out pcb */ LWIP_ASSERT("tcp_pcb_purge: listen pcb does not have accepts pending", lpcb->accepts_pending > 0); lpcb->accepts_pending--; break; } } } #endif /* TCP_LISTEN_BACKLOG */ if (pcb->refused_data != NULL) { LWIP_DEBUGF(TCP_DEBUG, ("tcp_pcb_purge: data left on ->refused_data\n")); pbuf_free(pcb->refused_data); pcb->refused_data = NULL; } if (pcb->unsent != NULL) { LWIP_DEBUGF(TCP_DEBUG, ("tcp_pcb_purge: not all data sent\n")); } if (pcb->unacked != NULL) { LWIP_DEBUGF(TCP_DEBUG, ("tcp_pcb_purge: data left on ->unacked\n")); } #if TCP_QUEUE_OOSEQ if (pcb->ooseq != NULL) { LWIP_DEBUGF(TCP_DEBUG, ("tcp_pcb_purge: data left on ->ooseq\n")); } tcp_segs_free(pcb->ooseq); pcb->ooseq = NULL; #endif /* TCP_QUEUE_OOSEQ */ /* Stop the retransmission timer as it will expect data on unacked queue if it fires */ pcb->rtime = -1; tcp_segs_free(pcb->unsent); tcp_segs_free(pcb->unacked); pcb->unacked = pcb->unsent = NULL; #if TCP_OVERSIZE pcb->unsent_oversize = 0; #endif /* TCP_OVERSIZE */ } } /** * Purges the PCB and removes it from a PCB list. Any delayed ACKs are sent first. * * @param pcblist PCB list to purge. * @param pcb tcp_pcb to purge. The pcb itself is NOT deallocated! */ void tcp_pcb_remove(struct tcp_pcb **pcblist, struct tcp_pcb *pcb) { TCP_RMV(pcblist, pcb); tcp_pcb_purge(pcb); /* if there is an outstanding delayed ACKs, send it */ if (pcb->state != TIME_WAIT && pcb->state != LISTEN && pcb->flags & TF_ACK_DELAY) { pcb->flags |= TF_ACK_NOW; tcp_output(pcb); } if (pcb->state != LISTEN) { LWIP_ASSERT("unsent segments leaking", pcb->unsent == NULL); LWIP_ASSERT("unacked segments leaking", pcb->unacked == NULL); #if TCP_QUEUE_OOSEQ LWIP_ASSERT("ooseq segments leaking", pcb->ooseq == NULL); #endif /* TCP_QUEUE_OOSEQ */ } pcb->state = CLOSED; LWIP_ASSERT("tcp_pcb_remove: tcp_pcbs_sane()", tcp_pcbs_sane()); } /** * Calculates a new initial sequence number for new connections. * * @return u32_t pseudo random sequence number */ u32_t tcp_next_iss(void) { static u32_t iss = 6510; iss += tcp_ticks; /* XXX */ return iss; } #if TCP_CALCULATE_EFF_SEND_MSS /** * Calcluates the effective send mss that can be used for a specific IP address * by using ip_route to determin the netif used to send to the address and * calculating the minimum of TCP_MSS and that netif's mtu (if set). */ u16_t tcp_eff_send_mss(u16_t sendmss, ip_addr_t *addr) { u16_t mss_s; struct netif *outif; outif = ip_route(addr); if ((outif != NULL) && (outif->mtu != 0)) { mss_s = outif->mtu - IP_HLEN - TCP_HLEN; /* RFC 1122, chap 4.2.2.6: * Eff.snd.MSS = min(SendMSS+20, MMS_S) - TCPhdrsize - IPoptionsize * We correct for TCP options in tcp_write(), and don't support IP options. */ sendmss = LWIP_MIN(sendmss, mss_s); } return sendmss; } #endif /* TCP_CALCULATE_EFF_SEND_MSS */ const char* tcp_debug_state_str(enum tcp_state s) { return tcp_state_str[s]; } #if TCP_DEBUG || TCP_INPUT_DEBUG || TCP_OUTPUT_DEBUG /** * Print a tcp header for debugging purposes. * * @param tcphdr pointer to a struct tcp_hdr */ void tcp_debug_print(struct tcp_hdr *tcphdr) { LWIP_DEBUGF(TCP_DEBUG, ("TCP header:\n")); LWIP_DEBUGF(TCP_DEBUG, ("+-------------------------------+\n")); LWIP_DEBUGF(TCP_DEBUG, ("| %5"U16_F" | %5"U16_F" | (src port, dest port)\n", ntohs(tcphdr->src), ntohs(tcphdr->dest))); LWIP_DEBUGF(TCP_DEBUG, ("+-------------------------------+\n")); LWIP_DEBUGF(TCP_DEBUG, ("| %010"U32_F" | (seq no)\n", ntohl(tcphdr->seqno))); LWIP_DEBUGF(TCP_DEBUG, ("+-------------------------------+\n")); LWIP_DEBUGF(TCP_DEBUG, ("| %010"U32_F" | (ack no)\n", ntohl(tcphdr->ackno))); LWIP_DEBUGF(TCP_DEBUG, ("+-------------------------------+\n")); LWIP_DEBUGF(TCP_DEBUG, ("| %2"U16_F" | |%"U16_F"%"U16_F"%"U16_F"%"U16_F"%"U16_F"%"U16_F"| %5"U16_F" | (hdrlen, flags (", TCPH_HDRLEN(tcphdr), TCPH_FLAGS(tcphdr) >> 5 & 1, TCPH_FLAGS(tcphdr) >> 4 & 1, TCPH_FLAGS(tcphdr) >> 3 & 1, TCPH_FLAGS(tcphdr) >> 2 & 1, TCPH_FLAGS(tcphdr) >> 1 & 1, TCPH_FLAGS(tcphdr) & 1, ntohs(tcphdr->wnd))); tcp_debug_print_flags(TCPH_FLAGS(tcphdr)); LWIP_DEBUGF(TCP_DEBUG, ("), win)\n")); LWIP_DEBUGF(TCP_DEBUG, ("+-------------------------------+\n")); LWIP_DEBUGF(TCP_DEBUG, ("| 0x%04"X16_F" | %5"U16_F" | (chksum, urgp)\n", ntohs(tcphdr->chksum), ntohs(tcphdr->urgp))); LWIP_DEBUGF(TCP_DEBUG, ("+-------------------------------+\n")); } /** * Print a tcp state for debugging purposes. * * @param s enum tcp_state to print */ void tcp_debug_print_state(enum tcp_state s) { LWIP_DEBUGF(TCP_DEBUG, ("State: %s\n", tcp_state_str[s])); } /** * Print tcp flags for debugging purposes. * * @param flags tcp flags, all active flags are printed */ void tcp_debug_print_flags(u8_t flags) { if (flags & TCP_FIN) { LWIP_DEBUGF(TCP_DEBUG, ("FIN ")); } if (flags & TCP_SYN) { LWIP_DEBUGF(TCP_DEBUG, ("SYN ")); } if (flags & TCP_RST) { LWIP_DEBUGF(TCP_DEBUG, ("RST ")); } if (flags & TCP_PSH) { LWIP_DEBUGF(TCP_DEBUG, ("PSH ")); } if (flags & TCP_ACK) { LWIP_DEBUGF(TCP_DEBUG, ("ACK ")); } if (flags & TCP_URG) { LWIP_DEBUGF(TCP_DEBUG, ("URG ")); } if (flags & TCP_ECE) { LWIP_DEBUGF(TCP_DEBUG, ("ECE ")); } if (flags & TCP_CWR) { LWIP_DEBUGF(TCP_DEBUG, ("CWR ")); } LWIP_DEBUGF(TCP_DEBUG, ("\n")); } /** * Print all tcp_pcbs in every list for debugging purposes. */ void tcp_debug_print_pcbs(void) { struct tcp_pcb *pcb; LWIP_DEBUGF(TCP_DEBUG, ("Active PCB states:\n")); for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) { LWIP_DEBUGF(TCP_DEBUG, ("Local port %"U16_F", foreign port %"U16_F" snd_nxt %"U32_F" rcv_nxt %"U32_F" ", pcb->local_port, pcb->remote_port, pcb->snd_nxt, pcb->rcv_nxt)); tcp_debug_print_state(pcb->state); } LWIP_DEBUGF(TCP_DEBUG, ("Listen PCB states:\n")); for(pcb = (struct tcp_pcb *)tcp_listen_pcbs.pcbs; pcb != NULL; pcb = pcb->next) { LWIP_DEBUGF(TCP_DEBUG, ("Local port %"U16_F", foreign port %"U16_F" snd_nxt %"U32_F" rcv_nxt %"U32_F" ", pcb->local_port, pcb->remote_port, pcb->snd_nxt, pcb->rcv_nxt)); tcp_debug_print_state(pcb->state); } LWIP_DEBUGF(TCP_DEBUG, ("TIME-WAIT PCB states:\n")); for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) { LWIP_DEBUGF(TCP_DEBUG, ("Local port %"U16_F", foreign port %"U16_F" snd_nxt %"U32_F" rcv_nxt %"U32_F" ", pcb->local_port, pcb->remote_port, pcb->snd_nxt, pcb->rcv_nxt)); tcp_debug_print_state(pcb->state); } } /** * Check state consistency of the tcp_pcb lists. */ s16_t tcp_pcbs_sane(void) { struct tcp_pcb *pcb; for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) { LWIP_ASSERT("tcp_pcbs_sane: active pcb->state != CLOSED", pcb->state != CLOSED); LWIP_ASSERT("tcp_pcbs_sane: active pcb->state != LISTEN", pcb->state != LISTEN); LWIP_ASSERT("tcp_pcbs_sane: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT); } for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) { LWIP_ASSERT("tcp_pcbs_sane: tw pcb->state == TIME-WAIT", pcb->state == TIME_WAIT); } return 1; } #endif /* TCP_DEBUG */ #endif /* LWIP_TCP */