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minix3/lib/liblwip/core/tcp.c

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/**
* @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 <adam@sics.se>
*
*/
#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 "lwip/ip6.h"
#include "lwip/ip6_addr.h"
#include "lwip/nd6.h"
#include <string.h>
#ifndef TCP_LOCAL_PORT_RANGE_START
/* From http://www.iana.org/assignments/port-numbers:
"The Dynamic and/or Private Ports are those from 49152 through 65535" */
#define TCP_LOCAL_PORT_RANGE_START 0xc000
#define TCP_LOCAL_PORT_RANGE_END 0xffff
#define TCP_ENSURE_LOCAL_PORT_RANGE(port) (((port) & ~TCP_LOCAL_PORT_RANGE_START) + TCP_LOCAL_PORT_RANGE_START)
#endif
#if LWIP_TCP_KEEPALIVE
#define TCP_KEEP_DUR(pcb) ((pcb)->keep_cnt * (pcb)->keep_intvl)
#define TCP_KEEP_INTVL(pcb) ((pcb)->keep_intvl)
#else /* LWIP_TCP_KEEPALIVE */
#define TCP_KEEP_DUR(pcb) TCP_MAXIDLE
#define TCP_KEEP_INTVL(pcb) TCP_KEEPINTVL_DEFAULT
#endif /* LWIP_TCP_KEEPALIVE */
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"
};
/* last local TCP port */
static u16_t tcp_port = TCP_LOCAL_PORT_RANGE_START;
/* 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;
u8_t tcp_active_pcbs_changed;
/** Timer counter to handle calling slow-timer from tcp_tmr() */
static u8_t tcp_timer;
static u8_t tcp_timer_ctr;
static u16_t tcp_new_port(void);
/**
* Initialize this module.
*/
void
tcp_init(void)
{
#if LWIP_RANDOMIZE_INITIAL_LOCAL_PORTS && defined(LWIP_RAND)
tcp_port = TCP_ENSURE_LOCAL_PORT_RANGE(LWIP_RAND());
#endif /* LWIP_RANDOMIZE_INITIAL_LOCAL_PORTS && defined(LWIP_RAND) */
}
/**
* 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 == ESTABLISHED) || (pcb->state == CLOSE_WAIT))) {
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, PCB_ISIPV6(pcb));
tcp_pcb_purge(pcb);
TCP_RMV_ACTIVE(pcb);
if (pcb->state == ESTABLISHED) {
/* move to TIME_WAIT since we close actively */
pcb->state = TIME_WAIT;
TCP_REG(&tcp_tw_pcbs, pcb);
} else {
/* CLOSE_WAIT: deallocate the pcb since we already sent a RST for it */
memp_free(MEMP_TCP_PCB, 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. */
err = ERR_OK;
if (pcb->local_port != 0) {
TCP_RMV(&tcp_bound_pcbs, pcb);
}
memp_free(MEMP_TCP_PCB, pcb);
pcb = NULL;
break;
case LISTEN:
err = ERR_OK;
tcp_pcb_remove(&tcp_listen_pcbs.pcbs, pcb);
memp_free(MEMP_TCP_PCB_LISTEN, pcb);
pcb = NULL;
break;
case SYN_SENT:
err = ERR_OK;
TCP_PCB_REMOVE_ACTIVE(pcb);
memp_free(MEMP_TCP_PCB, pcb);
pcb = NULL;
snmp_inc_tcpattemptfails();
break;
case SYN_RCVD:
err = tcp_send_fin(pcb);
if (err == ERR_OK) {
snmp_inc_tcpattemptfails();
pcb->state = 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;
}
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);
}
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
*/
err_t
tcp_close(struct tcp_pcb *pcb)
{
#if TCP_DEBUG
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 unless shutting down both sides!
* Shutting down both sides is the same as calling tcp_close, so if it succeds,
* the PCB should not be referenced any more.
*
* @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: set a flag not to receive any more data... */
pcb->flags |= TF_RXCLOSED;
if (shut_tx) {
/* shutting down the tx AND rx side is the same as closing for the raw API */
return tcp_close_shutdown(pcb, 1);
}
/* ... and free buffered data */
if (pcb->refused_data != NULL) {
pbuf_free(pcb->refused_data);
pcb->refused_data = NULL;
}
}
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, shut_rx);
default:
/* Not (yet?) connected, cannot shutdown the TX side as that would bring us
into CLOSED state, where the PCB is deallocated. */
return ERR_CONN;
}
}
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;
#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 {
int send_rst = reset && (pcb->state != CLOSED);
seqno = pcb->snd_nxt;
ackno = pcb->rcv_nxt;
#if LWIP_CALLBACK_API
errf = pcb->errf;
#endif /* LWIP_CALLBACK_API */
errf_arg = pcb->callback_arg;
TCP_PCB_REMOVE_ACTIVE(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 (send_rst) {
LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_abandon: sending RST\n"));
tcp_rst(seqno, ackno, &pcb->local_ip, &pcb->remote_ip, pcb->local_port, pcb->remote_port, PCB_ISIPV6(pcb));
}
memp_free(MEMP_TCP_PCB, pcb);
TCP_EVENT_ERR(errf, errf_arg, ERR_ABRT);
}
}
/**
* 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_VAL if bind failed because the PCB is not in a valid state
* 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_VAL);
#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 (ip_get_option(pcb, SOF_REUSEADDR)) {
max_pcb_list = NUM_TCP_PCB_LISTS_NO_TIME_WAIT;
}
#endif /* SO_REUSE */
if (port == 0) {
port = tcp_new_port();
if (port == 0) {
return ERR_BUF;
}
}
/* 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 (!ip_get_option(pcb, SOF_REUSEADDR) ||
!ip_get_option(cpcb, SOF_REUSEADDR))
#endif /* SO_REUSE */
{
/* @todo: check accept_any_ip_version */
if (IP_PCB_IPVER_EQ(pcb, cpcb) &&
(ipX_addr_isany(PCB_ISIPV6(pcb), &cpcb->local_ip) ||
ipX_addr_isany(PCB_ISIPV6(pcb), ip_2_ipX(ipaddr)) ||
ipX_addr_cmp(PCB_ISIPV6(pcb), &cpcb->local_ip, ip_2_ipX(ipaddr)))) {
return ERR_USE;
}
}
}
}
}
if (!ipX_addr_isany(PCB_ISIPV6(pcb), ip_2_ipX(ipaddr))) {
ipX_addr_set(PCB_ISIPV6(pcb), &pcb->local_ip, ip_2_ipX(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.
*
* @param pcb the original tcp_pcb
* @param backlog the incoming connections queue limit
* @return tcp_pcb used for listening, consumes less memory.
*
* @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 (ip_get_option(pcb, SOF_REUSEADDR)) {
/* 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) &&
IP_PCB_IPVER_EQ(pcb, lpcb)) {
if (ipX_addr_cmp(PCB_ISIPV6(pcb), &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);
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;
ip_set_option(lpcb, SOF_ACCEPTCONN);
lpcb->ttl = pcb->ttl;
lpcb->tos = pcb->tos;
#if LWIP_IPV6
PCB_ISIPV6(lpcb) = PCB_ISIPV6(pcb);
lpcb->accept_any_ip_version = 0;
#endif /* LWIP_IPV6 */
ipX_addr_copy(PCB_ISIPV6(pcb), 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;
#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);
return (struct tcp_pcb *)lpcb;
}
#if LWIP_IPV6
/**
* Same as tcp_listen_with_backlog, but allows to accept IPv4 and IPv6
* connections, if the pcb's local address is set to ANY.
*/
struct tcp_pcb *
tcp_listen_dual_with_backlog(struct tcp_pcb *pcb, u8_t backlog)
{
struct tcp_pcb *lpcb;
lpcb = tcp_listen_with_backlog(pcb, backlog);
if ((lpcb != NULL) &&
ipX_addr_isany(PCB_ISIPV6(pcb), &pcb->local_ip)) {
/* The default behavior is to accept connections on either
* IPv4 or IPv6, if not bound. */
/* @see NETCONN_FLAG_IPV6_V6ONLY for changing this behavior */
((struct tcp_pcb_listen*)lpcb)->accept_any_ip_version = 1;
}
return lpcb;
}
#endif /* LWIP_IPV6 */
/**
* 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.
*
* @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;
/* pcb->state LISTEN not allowed here */
LWIP_ASSERT("don't call tcp_recved for listen-pcbs",
pcb->state != LISTEN);
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));
}
/**
* Allocate a new local TCP port.
*
* @return a new (free) local TCP port number
*/
static u16_t
tcp_new_port(void)
{
u8_t i;
u16_t n = 0;
struct tcp_pcb *pcb;
again:
if (tcp_port++ == TCP_LOCAL_PORT_RANGE_END) {
tcp_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 == tcp_port) {
if (++n > (TCP_LOCAL_PORT_RANGE_END - TCP_LOCAL_PORT_RANGE_START)) {
return 0;
}
goto again;
}
}
}
return tcp_port;
}
/**
* Connects to another host. The function given as the "connected"
* argument will be called when the connection has been established.
*
* @param pcb the tcp_pcb used to establish the connection
* @param ipaddr the remote ip address to connect to
* @param port the remote tcp port to connect to
* @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 connect from state CLOSED", pcb->state == CLOSED, return ERR_ISCONN);
LWIP_DEBUGF(TCP_DEBUG, ("tcp_connect to port %"U16_F"\n", port));
if (ipaddr != NULL) {
ipX_addr_set(PCB_ISIPV6(pcb), &pcb->remote_ip, ip_2_ipX(ipaddr));
} else {
return ERR_VAL;
}
pcb->remote_port = port;
/* check if we have a route to the remote host */
if (ipX_addr_isany(PCB_ISIPV6(pcb), &pcb->local_ip)) {
/* no local IP address set, yet. */
struct netif *netif;
ipX_addr_t *local_ip;
ipX_route_get_local_ipX(PCB_ISIPV6(pcb), &pcb->local_ip, &pcb->remote_ip, netif, local_ip);
if ((netif == NULL) || (local_ip == NULL)) {
/* Don't even try to send a SYN packet if we have no route
since that will fail. */
return ERR_RTE;
}
/* Use the address as local address of the pcb. */
ipX_addr_copy(PCB_ISIPV6(pcb), pcb->local_ip, *local_ip);
}
old_local_port = pcb->local_port;
if (pcb->local_port == 0) {
pcb->local_port = tcp_new_port();
if (pcb->local_port == 0) {
return ERR_BUF;
}
}
#if SO_REUSE
if (ip_get_option(pcb, SOF_REUSEADDR)) {
/* 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_PCB_IPVER_EQ(cpcb, pcb) &&
ipX_addr_cmp(PCB_ISIPV6(pcb), &cpcb->local_ip, &pcb->local_ip) &&
ipX_addr_cmp(PCB_ISIPV6(pcb), &cpcb->remote_ip, ip_2_ipX(ipaddr))) {
/* linux returns EISCONN here, but ERR_USE should be OK for us */
return ERR_USE;
}
}
}
}
#endif /* SO_REUSE */
iss = tcp_next_iss();
pcb->rcv_nxt = 0;
pcb->snd_nxt = iss;
pcb->lastack = iss - 1;
pcb->snd_lbb = iss - 1;
pcb->rcv_wnd = TCP_WND;
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;
#if TCP_CALCULATE_EFF_SEND_MSS
pcb->mss = tcp_eff_send_mss(pcb->mss, &pcb->local_ip, &pcb->remote_ip, PCB_ISIPV6(pcb));
#endif /* TCP_CALCULATE_EFF_SEND_MSS */
pcb->cwnd = 1;
pcb->ssthresh = pcb->mss * 10;
#if LWIP_CALLBACK_API
pcb->connected = connected;
#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 */
pcb->state = SYN_SENT;
if (old_local_port != 0) {
TCP_RMV(&tcp_bound_pcbs, pcb);
}
TCP_REG_ACTIVE(pcb);
snmp_inc_tcpactiveopens();
tcp_output(pcb);
}
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;
++tcp_timer_ctr;
tcp_slowtmr_start:
/* 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);
if (pcb->last_timer == tcp_timer_ctr) {
/* skip this pcb, we have already processed it */
pcb = pcb->next;
continue;
}
pcb->last_timer = tcp_timer_ctr;
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];
}
/* 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 this PCB is in FIN_WAIT_2 because of SHUT_WR don't let it time out. */
if (pcb->flags & TF_RXCLOSED) {
/* PCB was fully closed (either through close() or SHUT_RDWR):
normal FIN-WAIT timeout handling. */
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(ip_get_option(pcb, SOF_KEEPALIVE) &&
((pcb->state == ESTABLISHED) ||
(pcb->state == CLOSE_WAIT))) {
if((u32_t)(tcp_ticks - pcb->tmr) >
(pcb->keep_idle + TCP_KEEP_DUR(pcb)) / TCP_SLOW_INTERVAL)
{
LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: KEEPALIVE timeout. Aborting connection to "));
ipX_addr_debug_print(PCB_ISIPV6(pcb), TCP_DEBUG, &pcb->remote_ip);
LWIP_DEBUGF(TCP_DEBUG, ("\n"));
++pcb_remove;
++pcb_reset;
}
else if((u32_t)(tcp_ticks - pcb->tmr) >
(pcb->keep_idle + pcb->keep_cnt_sent * TCP_KEEP_INTVL(pcb))
/ TCP_SLOW_INTERVAL)
{
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_err_fn err_fn;
void *err_arg;
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, PCB_ISIPV6(pcb));
}
err_fn = pcb->errf;
err_arg = pcb->callback_arg;
pcb2 = pcb;
pcb = pcb->next;
memp_free(MEMP_TCP_PCB, pcb2);
tcp_active_pcbs_changed = 0;
TCP_EVENT_ERR(err_fn, err_arg, ERR_ABRT);
if (tcp_active_pcbs_changed) {
goto tcp_slowtmr_start;
}
} 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_active_pcbs_changed = 0;
TCP_EVENT_POLL(prev, err);
if (tcp_active_pcbs_changed) {
goto tcp_slowtmr_start;
}
/* 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_timer_ctr;
tcp_fasttmr_start:
pcb = tcp_active_pcbs;
while(pcb != NULL) {
if (pcb->last_timer != tcp_timer_ctr) {
struct tcp_pcb *next;
pcb->last_timer = tcp_timer_ctr;
/* send delayed ACKs */
if (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);
}
next = pcb->next;
/* If there is data which was previously "refused" by upper layer */
if (pcb->refused_data != NULL) {
tcp_active_pcbs_changed = 0;
tcp_process_refused_data(pcb);
if (tcp_active_pcbs_changed) {
/* application callback has changed the pcb list: restart the loop */
goto tcp_fasttmr_start;
}
}
pcb = next;
}
}
}
/** Pass pcb->refused_data to the recv callback */
err_t
tcp_process_refused_data(struct tcp_pcb *pcb)
{
err_t err;
u8_t refused_flags = pcb->refused_data->flags;
/* set pcb->refused_data to NULL in case the callback frees it and then
closes the pcb */
struct pbuf *refused_data = pcb->refused_data;
pcb->refused_data = NULL;
/* Notify again application with data previously received. */
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: notify kept packet\n"));
TCP_EVENT_RECV(pcb, refused_data, ERR_OK, err);
if (err == ERR_OK) {
/* did refused_data include a FIN? */
if (refused_flags & PBUF_FLAG_TCP_FIN) {
/* correct rcv_wnd as the application won't call tcp_recved()
for the FIN's seqno */
if (pcb->rcv_wnd != TCP_WND) {
pcb->rcv_wnd++;
}
TCP_EVENT_CLOSED(pcb, err);
if (err == ERR_ABRT) {
return ERR_ABRT;
}
}
} else if (err == ERR_ABRT) {
/* if err == ERR_ABRT, 'pcb' is already deallocated */
/* Drop incoming packets because pcb is "full" (only if the incoming
segment contains data). */
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: drop incoming packets, because pcb is \"full\"\n"));
return ERR_ABRT;
} else {
/* data is still refused, pbuf is still valid (go on for ACK-only packets) */
pcb->refused_data = refused_data;
}
return ERR_OK;
}
/**
* 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 the same or lower priority than
* 'prio'.
*
* @param prio minimum priority
*/
static void
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
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.
*
* @param prio priority for the new pcb
* @return a new tcp_pcb that initially is in state CLOSED
*/
struct tcp_pcb *
tcp_alloc(u8_t prio)
{
struct tcp_pcb *pcb;
u32_t iss;
pcb = (struct tcp_pcb *)memp_malloc(MEMP_TCP_PCB);
if (pcb == NULL) {
/* 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));
pcb->prio = prio;
pcb->snd_buf = TCP_SND_BUF;
pcb->snd_queuelen = 0;
pcb->rcv_wnd = TCP_WND;
pcb->rcv_ann_wnd = TCP_WND;
pcb->tos = 0;
pcb->ttl = TCP_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;
pcb->rto = 3000 / TCP_SLOW_INTERVAL;
pcb->sa = 0;
pcb->sv = 3000 / TCP_SLOW_INTERVAL;
pcb->rtime = -1;
pcb->cwnd = 1;
iss = tcp_next_iss();
pcb->snd_wl2 = iss;
pcb->snd_nxt = iss;
pcb->lastack = iss;
pcb->snd_lbb = iss;
pcb->tmr = tcp_ticks;
pcb->last_timer = tcp_timer_ctr;
pcb->polltmr = 0;
#if LWIP_CALLBACK_API
pcb->recv = tcp_recv_null;
#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;
}
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);
}
#if LWIP_IPV6
/**
* Creates a new TCP-over-IPv6 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().
*
* @return a new tcp_pcb that initially is in state CLOSED
*/
struct tcp_pcb *
tcp_new_ip6(void)
{
struct tcp_pcb * pcb;
pcb = tcp_alloc(TCP_PRIO_NORMAL);
ip_set_v6(pcb, 1);
return pcb;
}
#endif /* LWIP_IPV6 */
/**
* Used to specify the argument that should be passed callback
* functions.
*
* @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)
{
/* This function is allowed to be called for both listen pcbs and
connection pcbs. */
pcb->callback_arg = arg;
}
#if LWIP_CALLBACK_API
/**
* Used to specify the function that should be called when a TCP
* connection receives data.
*
* @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)
{
LWIP_ASSERT("invalid socket state for recv callback", pcb->state != LISTEN);
pcb->recv = recv;
}
/**
* Used to specify the function that should be called when TCP data
* has been successfully delivered to the remote host.
*
* @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)
{
LWIP_ASSERT("invalid socket state for sent callback", pcb->state != LISTEN);
pcb->sent = sent;
}
/**
* Used to specify the function that should be called when a fatal error
* has occured on the connection.
*
* @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)
{
LWIP_ASSERT("invalid socket state for err callback", pcb->state != LISTEN);
pcb->errf = err;
}
/**
* Used for specifying the function that should be called when a
* LISTENing connection has been connected to another host.
*
* @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)
{
/* This function is allowed to be called for both listen pcbs and
connection pcbs. */
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.
*
*/
void
tcp_poll(struct tcp_pcb *pcb, tcp_poll_fn poll, u8_t interval)
{
LWIP_ASSERT("invalid socket state for poll", pcb->state != LISTEN);
#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_PCB_IPVER_EQ(pcb, lpcb) &&
(ipX_addr_isany(PCB_ISIPV6(lpcb), &lpcb->local_ip) ||
ipX_addr_cmp(PCB_ISIPV6(lpcb), &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_impl(u16_t sendmss, ipX_addr_t *dest
#if LWIP_IPV6
, ipX_addr_t *src, u8_t isipv6
#endif /* LWIP_IPV6 */
)
{
u16_t mss_s;
struct netif *outif;
s16_t mtu;
outif = ipX_route(isipv6, src, dest);
#if LWIP_IPV6
if (isipv6) {
/* First look in destination cache, to see if there is a Path MTU. */
mtu = nd6_get_destination_mtu(ipX_2_ip6(dest), outif);
} else
#endif /* LWIP_IPV6 */
{
if (outif == NULL) {
return sendmss;
}
mtu = outif->mtu;
}
if (mtu != 0) {
mss_s = mtu - IP_HLEN - TCP_HLEN;
#if LWIP_IPV6
/* for IPv6, substract the difference in header size */
mss_s -= (IP6_HLEN - IP_HLEN);
#endif /* LWIP_IPV6 */
/* 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 */
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