Remove netcon from dev branch. This is moving to its own new ZeroTierSDK repo for future release under the SDK name.

1 files changed, 0 insertions, 1619 deletions

diff --git a/ext/lwip/src/core/tcp_in.c b/ext/lwip/src/core/tcp_in.c
deleted file mode 100644
index 051869ff..00000000
--- a/ext/lwip/src/core/tcp_in.c
+++ /dev/null
@@ -1,1619 +0,0 @@
-/**
- * @file
- * Transmission Control Protocol, incoming traffic
- *
- * The input processing functions of the TCP layer.
- *
- * These functions are generally called in the order (ip_input() ->)
- * tcp_input() -> * tcp_process() -> tcp_receive() (-> application).
- *
- */
-
-/*
- * 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/tcp_impl.h"
-#include "lwip/def.h"
-#include "lwip/ip_addr.h"
-#include "lwip/netif.h"
-#include "lwip/mem.h"
-#include "lwip/memp.h"
-#include "lwip/inet_chksum.h"
-#include "lwip/stats.h"
-#include "lwip/snmp.h"
-#include "arch/perf.h"
-
-/* These variables are global to all functions involved in the input
-   processing of TCP segments. They are set by the tcp_input()
-   function. */
-static struct tcp_seg inseg;
-static struct tcp_hdr *tcphdr;
-static struct ip_hdr *iphdr;
-static u32_t seqno, ackno;
-static u8_t flags;
-static u16_t tcplen;
-
-static u8_t recv_flags;
-static struct pbuf *recv_data;
-
-struct tcp_pcb *tcp_input_pcb;
-
-/* Forward declarations. */
-static err_t tcp_process(struct tcp_pcb *pcb);
-static void tcp_receive(struct tcp_pcb *pcb);
-static void tcp_parseopt(struct tcp_pcb *pcb);
-
-static err_t tcp_listen_input(struct tcp_pcb_listen *pcb);
-static err_t tcp_timewait_input(struct tcp_pcb *pcb);
-
-/**
- * The initial input processing of TCP. It verifies the TCP header, demultiplexes
- * the segment between the PCBs and passes it on to tcp_process(), which implements
- * the TCP finite state machine. This function is called by the IP layer (in
- * ip_input()).
- *
- * @param p received TCP segment to process (p->payload pointing to the IP header)
- * @param inp network interface on which this segment was received
- */
-void
-tcp_input(struct pbuf *p, struct netif *inp)
-{
-  struct tcp_pcb *pcb, *prev;
-  struct tcp_pcb_listen *lpcb;
-#if SO_REUSE
-  struct tcp_pcb *lpcb_prev = NULL;
-  struct tcp_pcb_listen *lpcb_any = NULL;
-#endif /* SO_REUSE */
-  u8_t hdrlen;
-  err_t err;
-
-  PERF_START;
-
-  TCP_STATS_INC(tcp.recv);
-  snmp_inc_tcpinsegs();
-
-  iphdr = (struct ip_hdr *)p->payload;
-  tcphdr = (struct tcp_hdr *)((u8_t *)p->payload + IPH_HL(iphdr) * 4);
-
-#if TCP_INPUT_DEBUG
-  tcp_debug_print(tcphdr);
-#endif
-
-  /* remove header from payload */
-  if (pbuf_header(p, -((s16_t)(IPH_HL(iphdr) * 4))) || (p->tot_len < sizeof(struct tcp_hdr))) {
-    /* drop short packets */
-    LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet (%"U16_F" bytes) discarded\n", p->tot_len));
-    TCP_STATS_INC(tcp.lenerr);
-    goto dropped;
-  }
-
-  /* Don't even process incoming broadcasts/multicasts. */
-  if (ip_addr_isbroadcast(&current_iphdr_dest, inp) ||
-      ip_addr_ismulticast(&current_iphdr_dest)) {
-    TCP_STATS_INC(tcp.proterr);
-    goto dropped;
-  }
-
-#if CHECKSUM_CHECK_TCP
-  /* Verify TCP checksum. */
-  if (inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
-      IP_PROTO_TCP, p->tot_len) != 0) {
-      LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packet discarded due to failing checksum 0x%04"X16_F"\n",
-        inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
-      IP_PROTO_TCP, p->tot_len)));
-#if TCP_DEBUG
-    tcp_debug_print(tcphdr);
-#endif /* TCP_DEBUG */
-    TCP_STATS_INC(tcp.chkerr);
-    goto dropped;
-  }
-#endif
-
-  /* Move the payload pointer in the pbuf so that it points to the
-     TCP data instead of the TCP header. */
-  hdrlen = TCPH_HDRLEN(tcphdr);
-  if(pbuf_header(p, -(hdrlen * 4))){
-    /* drop short packets */
-    LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet\n"));
-    TCP_STATS_INC(tcp.lenerr);
-    goto dropped;
-  }
-
-  /* Convert fields in TCP header to host byte order. */
-  tcphdr->src = ntohs(tcphdr->src);
-  tcphdr->dest = ntohs(tcphdr->dest);
-  seqno = tcphdr->seqno = ntohl(tcphdr->seqno);
-  ackno = tcphdr->ackno = ntohl(tcphdr->ackno);
-  tcphdr->wnd = ntohs(tcphdr->wnd);
-
-  flags = TCPH_FLAGS(tcphdr);
-  tcplen = p->tot_len + ((flags & (TCP_FIN | TCP_SYN)) ? 1 : 0);
-
-  /* Demultiplex an incoming segment. First, we check if it is destined
-     for an active connection. */
-  prev = NULL;
-
-
-  for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
-    LWIP_ASSERT("tcp_input: active pcb->state != CLOSED", pcb->state != CLOSED);
-    LWIP_ASSERT("tcp_input: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT);
-    LWIP_ASSERT("tcp_input: active pcb->state != LISTEN", pcb->state != LISTEN);
-    if (pcb->remote_port == tcphdr->src &&
-       pcb->local_port == tcphdr->dest &&
-       ip_addr_cmp(&(pcb->remote_ip), &current_iphdr_src) &&
-       ip_addr_cmp(&(pcb->local_ip), &current_iphdr_dest)) {
-
-      /* Move this PCB to the front of the list so that subsequent
-         lookups will be faster (we exploit locality in TCP segment
-         arrivals). */
-      LWIP_ASSERT("tcp_input: pcb->next != pcb (before cache)", pcb->next != pcb);
-      if (prev != NULL) {
-        prev->next = pcb->next;
-        pcb->next = tcp_active_pcbs;
-        tcp_active_pcbs = pcb;
-      }
-      LWIP_ASSERT("tcp_input: pcb->next != pcb (after cache)", pcb->next != pcb);
-      break;
-    }
-    prev = pcb;
-  }
-
-  if (pcb == NULL) {
-    /* If it did not go to an active connection, we check the connections
-       in the TIME-WAIT state. */
-    for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
-      LWIP_ASSERT("tcp_input: TIME-WAIT pcb->state == TIME-WAIT", pcb->state == TIME_WAIT);
-      if (pcb->remote_port == tcphdr->src &&
-         pcb->local_port == tcphdr->dest &&
-         ip_addr_cmp(&(pcb->remote_ip), &current_iphdr_src) &&
-         ip_addr_cmp(&(pcb->local_ip), &current_iphdr_dest)) {
-        /* We don't really care enough to move this PCB to the front
-           of the list since we are not very likely to receive that
-           many segments for connections in TIME-WAIT. */
-        LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for TIME_WAITing connection.\n"));
-        tcp_timewait_input(pcb);
-        pbuf_free(p);
-        return;
-      }
-    }
-
-    /* Finally, if we still did not get a match, we check all PCBs that
-       are LISTENing for incoming connections. */
-    prev = NULL;
-    for(lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
-      if (lpcb->local_port == tcphdr->dest) {
-#if SO_REUSE
-        if (ip_addr_cmp(&(lpcb->local_ip), &current_iphdr_dest)) {
-          /* found an exact match */
-          break;
-        } else if(ip_addr_isany(&(lpcb->local_ip))) {
-          /* found an ANY-match */
-          lpcb_any = lpcb;
-          lpcb_prev = prev;
-        }
-#else /* SO_REUSE */
-        if (ip_addr_cmp(&(lpcb->local_ip), &current_iphdr_dest) ||
-            ip_addr_isany(&(lpcb->local_ip))) {
-          /* found a match */
-          break;
-        }
-#endif /* SO_REUSE */
-      }
-      prev = (struct tcp_pcb *)lpcb;
-    }
-#if SO_REUSE
-    /* first try specific local IP */
-    if (lpcb == NULL) {
-      /* only pass to ANY if no specific local IP has been found */
-      lpcb = lpcb_any;
-      prev = lpcb_prev;
-    }
-#endif /* SO_REUSE */
-    if (lpcb != NULL) {
-      /* Move this PCB to the front of the list so that subsequent
-         lookups will be faster (we exploit locality in TCP segment
-         arrivals). */
-      if (prev != NULL) {
-        ((struct tcp_pcb_listen *)prev)->next = lpcb->next;
-              /* our successor is the remainder of the listening list */
-        lpcb->next = tcp_listen_pcbs.listen_pcbs;
-              /* put this listening pcb at the head of the listening list */
-        tcp_listen_pcbs.listen_pcbs = lpcb;
-      }
-
-      LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for LISTENing connection.\n"));
-      tcp_listen_input(lpcb);
-      pbuf_free(p);
-      return;
-    }
-  }
-
-#if TCP_INPUT_DEBUG
-  LWIP_DEBUGF(TCP_INPUT_DEBUG, ("+-+-+-+-+-+-+-+-+-+-+-+-+-+- tcp_input: flags "));
-  tcp_debug_print_flags(TCPH_FLAGS(tcphdr));
-  LWIP_DEBUGF(TCP_INPUT_DEBUG, ("-+-+-+-+-+-+-+-+-+-+-+-+-+-+\n"));
-#endif /* TCP_INPUT_DEBUG */
-
-
-  if (pcb != NULL) {
-    /* The incoming segment belongs to a connection. */
-#if TCP_INPUT_DEBUG
-#if TCP_DEBUG
-    tcp_debug_print_state(pcb->state);
-#endif /* TCP_DEBUG */
-#endif /* TCP_INPUT_DEBUG */
-
-    /* Set up a tcp_seg structure. */
-    inseg.next = NULL;
-    inseg.len = p->tot_len;
-    inseg.p = p;
-    inseg.tcphdr = tcphdr;
-
-    recv_data = NULL;
-    recv_flags = 0;
-
-    if (flags & TCP_PSH) {
-      p->flags |= PBUF_FLAG_PUSH;
-    }
-
-    /* If there is data which was previously "refused" by upper layer */
-    if (pcb->refused_data != NULL) {
-      if ((tcp_process_refused_data(pcb) == ERR_ABRT) ||
-        ((pcb->refused_data != NULL) && (tcplen > 0))) {
-        /* pcb has been aborted or refused data is still refused and the new
-           segment contains data */
-        TCP_STATS_INC(tcp.drop);
-        snmp_inc_tcpinerrs();
-        goto aborted;
-      }
-    }
-    tcp_input_pcb = pcb;
-    err = tcp_process(pcb);
-    /* A return value of ERR_ABRT means that tcp_abort() was called
-       and that the pcb has been freed. If so, we don't do anything. */
-    if (err != ERR_ABRT) {
-      if (recv_flags & TF_RESET) {
-        /* TF_RESET means that the connection was reset by the other
-           end. We then call the error callback to inform the
-           application that the connection is dead before we
-           deallocate the PCB. */
-        TCP_EVENT_ERR(pcb->errf, pcb->callback_arg, ERR_RST);
-        tcp_pcb_remove(&tcp_active_pcbs, pcb);
-        memp_free(MEMP_TCP_PCB, pcb);
-      } else if (recv_flags & TF_CLOSED) {
-        /* The connection has been closed and we will deallocate the
-           PCB. */
-        if (!(pcb->flags & TF_RXCLOSED)) {
-          /* Connection closed although the application has only shut down the
-             tx side: call the PCB's err callback and indicate the closure to
-             ensure the application doesn't continue using the PCB. */
-          TCP_EVENT_ERR(pcb->errf, pcb->callback_arg, ERR_CLSD);
-        }
-        tcp_pcb_remove(&tcp_active_pcbs, pcb);
-        memp_free(MEMP_TCP_PCB, pcb);
-      } else {
-        err = ERR_OK;
-        /* If the application has registered a "sent" function to be
-           called when new send buffer space is available, we call it
-           now. */
-        if (pcb->acked > 0) {
-          TCP_EVENT_SENT(pcb, pcb->acked, err);
-          if (err == ERR_ABRT) {
-            goto aborted;
-          }
-        }
-
-        if (recv_data != NULL) {
-          LWIP_ASSERT("pcb->refused_data == NULL", pcb->refused_data == NULL);
-          if (pcb->flags & TF_RXCLOSED) {
-            /* received data although already closed -> abort (send RST) to
-               notify the remote host that not all data has been processed */
-            pbuf_free(recv_data);
-            tcp_abort(pcb);
-            goto aborted;
-          }
-
-          /* Notify application that data has been received. */
-          TCP_EVENT_RECV(pcb, recv_data, ERR_OK, err);
-          if (err == ERR_ABRT) {
-            goto aborted;
-          }
-
-          /* If the upper layer can't receive this data, store it */
-          if (err != ERR_OK) {
-            pcb->refused_data = recv_data;
-            LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: keep incoming packet, because pcb is \"full\"\n"));
-          }
-        }
-
-        /* If a FIN segment was received, we call the callback
-           function with a NULL buffer to indicate EOF. */
-        if (recv_flags & TF_GOT_FIN) {
-          if (pcb->refused_data != NULL) {
-            /* Delay this if we have refused data. */
-            pcb->refused_data->flags |= PBUF_FLAG_TCP_FIN;
-          } else {
-            /* 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) {
-              goto aborted;
-            }
-          }
-        }
-
-        tcp_input_pcb = NULL;
-        /* Try to send something out. */
-        tcp_output(pcb);
-#if TCP_INPUT_DEBUG
-#if TCP_DEBUG
-        tcp_debug_print_state(pcb->state);
-#endif /* TCP_DEBUG */
-#endif /* TCP_INPUT_DEBUG */
-      }
-    }
-    /* Jump target if pcb has been aborted in a callback (by calling tcp_abort()).
-       Below this line, 'pcb' may not be dereferenced! */
-aborted:
-    tcp_input_pcb = NULL;
-    recv_data = NULL;
-
-    /* give up our reference to inseg.p */
-    if (inseg.p != NULL)
-    {
-      pbuf_free(inseg.p);
-      inseg.p = NULL;
-    }
-  } else {
-
-    /* If no matching PCB was found, send a TCP RST (reset) to the
-       sender. */
-    LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_input: no PCB match found, resetting.\n"));
-    if (!(TCPH_FLAGS(tcphdr) & TCP_RST)) {
-      TCP_STATS_INC(tcp.proterr);
-      TCP_STATS_INC(tcp.drop);
-      tcp_rst(ackno, seqno + tcplen,
-        ip_current_dest_addr(), ip_current_src_addr(),
-        tcphdr->dest, tcphdr->src);
-    }
-    pbuf_free(p);
-  }
-
-  LWIP_ASSERT("tcp_input: tcp_pcbs_sane()", tcp_pcbs_sane());
-  PERF_STOP("tcp_input");
-  return;
-dropped:
-  TCP_STATS_INC(tcp.drop);
-  snmp_inc_tcpinerrs();
-  pbuf_free(p);
-}
-
-/**
- * Called by tcp_input() when a segment arrives for a listening
- * connection (from tcp_input()).
- *
- * @param pcb the tcp_pcb_listen for which a segment arrived
- * @return ERR_OK if the segment was processed
- *         another err_t on error
- *
- * @note the return value is not (yet?) used in tcp_input()
- * @note the segment which arrived is saved in global variables, therefore only the pcb
- *       involved is passed as a parameter to this function
- */
-static err_t
-tcp_listen_input(struct tcp_pcb_listen *pcb)
-{
-  struct tcp_pcb *npcb;
-  err_t rc;
-
-  if (flags & TCP_RST) {
-    /* An incoming RST should be ignored. Return. */
-    return ERR_OK;
-  }
-
-  /* In the LISTEN state, we check for incoming SYN segments,
-     creates a new PCB, and responds with a SYN|ACK. */
-  if (flags & TCP_ACK) {
-    /* For incoming segments with the ACK flag set, respond with a
-       RST. */
-    LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_listen_input: ACK in LISTEN, sending reset\n"));
-    tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(),
-      ip_current_src_addr(), tcphdr->dest, tcphdr->src);
-  } else if (flags & TCP_SYN) {
-    LWIP_DEBUGF(TCP_DEBUG, ("TCP connection request %"U16_F" -> %"U16_F".\n", tcphdr->src, tcphdr->dest));
-#if TCP_LISTEN_BACKLOG
-    if (pcb->accepts_pending >= pcb->backlog) {
-      LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: listen backlog exceeded for port %"U16_F"\n", tcphdr->dest));
-      return ERR_ABRT;
-    }
-#endif /* TCP_LISTEN_BACKLOG */
-    npcb = tcp_alloc(pcb->prio);
-    /* If a new PCB could not be created (probably due to lack of memory),
-       we don't do anything, but rely on the sender will retransmit the
-       SYN at a time when we have more memory available. */
-    if (npcb == NULL) {
-      LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: could not allocate PCB\n"));
-      TCP_STATS_INC(tcp.memerr);
-      return ERR_MEM;
-    }
-#if TCP_LISTEN_BACKLOG
-    pcb->accepts_pending++;
-#endif /* TCP_LISTEN_BACKLOG */
-    /* Set up the new PCB. */
-    ip_addr_copy(npcb->local_ip, current_iphdr_dest);
-    npcb->local_port = pcb->local_port;
-    ip_addr_copy(npcb->remote_ip, current_iphdr_src);
-    npcb->remote_port = tcphdr->src;
-    npcb->state = SYN_RCVD;
-    npcb->rcv_nxt = seqno + 1;
-    npcb->rcv_ann_right_edge = npcb->rcv_nxt;
-    npcb->snd_wnd = tcphdr->wnd;
-    npcb->snd_wnd_max = tcphdr->wnd;
-    npcb->ssthresh = npcb->snd_wnd;
-    npcb->snd_wl1 = seqno - 1;/* initialise to seqno-1 to force window update */
-    npcb->callback_arg = pcb->callback_arg;
-#if LWIP_CALLBACK_API
-    npcb->accept = pcb->accept;
-#endif /* LWIP_CALLBACK_API */
-    /* inherit socket options */
-    npcb->so_options = pcb->so_options & SOF_INHERITED;
-    /* Register the new PCB so that we can begin receiving segments
-       for it. */
-    TCP_REG_ACTIVE(npcb);
-
-    /* Parse any options in the SYN. */
-    tcp_parseopt(npcb);
-#if TCP_CALCULATE_EFF_SEND_MSS
-    npcb->mss = tcp_eff_send_mss(npcb->mss, &(npcb->remote_ip));
-#endif /* TCP_CALCULATE_EFF_SEND_MSS */
-
-    snmp_inc_tcppassiveopens();
-
-    /* Send a SYN|ACK together with the MSS option. */
-    rc = tcp_enqueue_flags(npcb, TCP_SYN | TCP_ACK);
-    if (rc != ERR_OK) {
-      tcp_abandon(npcb, 0);
-      return rc;
-    }
-    return tcp_output(npcb);
-  }
-  return ERR_OK;
-}
-
-/**
- * Called by tcp_input() when a segment arrives for a connection in
- * TIME_WAIT.
- *
- * @param pcb the tcp_pcb for which a segment arrived
- *
- * @note the segment which arrived is saved in global variables, therefore only the pcb
- *       involved is passed as a parameter to this function
- */
-static err_t
-tcp_timewait_input(struct tcp_pcb *pcb)
-{
-  /* RFC 1337: in TIME_WAIT, ignore RST and ACK FINs + any 'acceptable' segments */
-  /* RFC 793 3.9 Event Processing - Segment Arrives:
-   * - first check sequence number - we skip that one in TIME_WAIT (always
-   *   acceptable since we only send ACKs)
-   * - second check the RST bit (... return) */
-  if (flags & TCP_RST)  {
-    return ERR_OK;
-  }
-  /* - fourth, check the SYN bit, */
-  if (flags & TCP_SYN) {
-    /* If an incoming segment is not acceptable, an acknowledgment
-       should be sent in reply */
-    if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt+pcb->rcv_wnd)) {
-      /* If the SYN is in the window it is an error, send a reset */
-      tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
-        tcphdr->dest, tcphdr->src);
-      return ERR_OK;
-    }
-  } else if (flags & TCP_FIN) {
-    /* - eighth, check the FIN bit: Remain in the TIME-WAIT state.
-         Restart the 2 MSL time-wait timeout.*/
-    pcb->tmr = tcp_ticks;
-  }
-
-  if ((tcplen > 0))  {
-    /* Acknowledge data, FIN or out-of-window SYN */
-    pcb->flags |= TF_ACK_NOW;
-    return tcp_output(pcb);
-  }
-  return ERR_OK;
-}
-
-/**
- * Implements the TCP state machine. Called by tcp_input. In some
- * states tcp_receive() is called to receive data. The tcp_seg
- * argument will be freed by the caller (tcp_input()) unless the
- * recv_data pointer in the pcb is set.
- *
- * @param pcb the tcp_pcb for which a segment arrived
- *
- * @note the segment which arrived is saved in global variables, therefore only the pcb
- *       involved is passed as a parameter to this function
- */
-static err_t
-tcp_process(struct tcp_pcb *pcb)
-{
-  struct tcp_seg *rseg;
-  u8_t acceptable = 0;
-  err_t err;
-
-  err = ERR_OK;
-
-  /* Process incoming RST segments. */
-  if (flags & TCP_RST) {
-    /* First, determine if the reset is acceptable. */
-    if (pcb->state == SYN_SENT) {
-      if (ackno == pcb->snd_nxt) {
-        acceptable = 1;
-      }
-    } else {
-      if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
-                          pcb->rcv_nxt+pcb->rcv_wnd)) {
-        acceptable = 1;
-      }
-    }
-
-    if (acceptable) {
-      LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: Connection RESET\n"));
-      LWIP_ASSERT("tcp_input: pcb->state != CLOSED", pcb->state != CLOSED);
-      recv_flags |= TF_RESET;
-      pcb->flags &= ~TF_ACK_DELAY;
-      return ERR_RST;
-    } else {
-      LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
-       seqno, pcb->rcv_nxt));
-      LWIP_DEBUGF(TCP_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
-       seqno, pcb->rcv_nxt));
-      return ERR_OK;
-    }
-  }
-
-  if ((flags & TCP_SYN) && (pcb->state != SYN_SENT && pcb->state != SYN_RCVD)) {
-    /* Cope with new connection attempt after remote end crashed */
-    tcp_ack_now(pcb);
-    return ERR_OK;
-  }
-
-  if ((pcb->flags & TF_RXCLOSED) == 0) {
-    /* Update the PCB (in)activity timer unless rx is closed (see tcp_shutdown) */
-    pcb->tmr = tcp_ticks;
-  }
-  pcb->keep_cnt_sent = 0;
-
-  tcp_parseopt(pcb);
-
-  /* Do different things depending on the TCP state. */
-  switch (pcb->state) {
-  case SYN_SENT:
-    LWIP_DEBUGF(TCP_INPUT_DEBUG, ("SYN-SENT: ackno %"U32_F" pcb->snd_nxt %"U32_F" unacked %"U32_F"\n", ackno,
-     pcb->snd_nxt, ntohl(pcb->unacked->tcphdr->seqno)));
-    /* received SYN ACK with expected sequence number? */
-    if ((flags & TCP_ACK) && (flags & TCP_SYN)
-        && ackno == ntohl(pcb->unacked->tcphdr->seqno) + 1) {
-      pcb->snd_buf++;
-      pcb->rcv_nxt = seqno + 1;
-      pcb->rcv_ann_right_edge = pcb->rcv_nxt;
-      pcb->lastack = ackno;
-      pcb->snd_wnd = tcphdr->wnd;
-      pcb->snd_wnd_max = tcphdr->wnd;
-      pcb->snd_wl1 = seqno - 1; /* initialise to seqno - 1 to force window update */
-      pcb->state = ESTABLISHED;
-
-#if TCP_CALCULATE_EFF_SEND_MSS
-      pcb->mss = tcp_eff_send_mss(pcb->mss, &(pcb->remote_ip));
-#endif /* TCP_CALCULATE_EFF_SEND_MSS */
-
-      /* Set ssthresh again after changing pcb->mss (already set in tcp_connect
-       * but for the default value of pcb->mss) */
-      pcb->ssthresh = pcb->mss * 10;
-
-      pcb->cwnd = ((pcb->cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
-      LWIP_ASSERT("pcb->snd_queuelen > 0", (pcb->snd_queuelen > 0));
-      --pcb->snd_queuelen;
-      LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_process: SYN-SENT --queuelen %"U16_F"\n", (u16_t)pcb->snd_queuelen));
-      rseg = pcb->unacked;
-      pcb->unacked = rseg->next;
-      tcp_seg_free(rseg);
-
-      /* If there's nothing left to acknowledge, stop the retransmit
-         timer, otherwise reset it to start again */
-      if(pcb->unacked == NULL)
-        pcb->rtime = -1;
-      else {
-        pcb->rtime = 0;
-        pcb->nrtx = 0;
-      }
-
-      /* Call the user specified function to call when sucessfully
-       * connected. */
-      TCP_EVENT_CONNECTED(pcb, ERR_OK, err);
-      if (err == ERR_ABRT) {
-        return ERR_ABRT;
-      }
-      tcp_ack_now(pcb);
-    }
-    /* received ACK? possibly a half-open connection */
-    else if (flags & TCP_ACK) {
-      /* send a RST to bring the other side in a non-synchronized state. */
-      tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
-        tcphdr->dest, tcphdr->src);
-    }
-    break;
-  case SYN_RCVD:
-    if (flags & TCP_ACK) {
-      /* expected ACK number? */
-      if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)) {
-        u16_t old_cwnd;
-        pcb->state = ESTABLISHED;
-        LWIP_DEBUGF(TCP_DEBUG, ("TCP connection established %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
-#if LWIP_CALLBACK_API
-        LWIP_ASSERT("pcb->accept != NULL", pcb->accept != NULL);
-#endif
-        /* Call the accept function. */
-        TCP_EVENT_ACCEPT(pcb, ERR_OK, err);
-        if (err != ERR_OK) {
-          /* If the accept function returns with an error, we abort
-           * the connection. */
-          /* Already aborted? */
-          if (err != ERR_ABRT) {
-            tcp_abort(pcb);
-          }
-          return ERR_ABRT;
-        }
-        old_cwnd = pcb->cwnd;
-        /* If there was any data contained within this ACK,
-         * we'd better pass it on to the application as well. */
-        tcp_receive(pcb);
-
-        /* Prevent ACK for SYN to generate a sent event */
-        if (pcb->acked != 0) {
-          pcb->acked--;
-        }
-
-        pcb->cwnd = ((old_cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
-
-        if (recv_flags & TF_GOT_FIN) {
-          tcp_ack_now(pcb);
-          pcb->state = CLOSE_WAIT;
-        }
-      } else {
-        /* incorrect ACK number, send RST */
-        tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
-                tcphdr->dest, tcphdr->src);
-      }
-    } else if ((flags & TCP_SYN) && (seqno == pcb->rcv_nxt - 1)) {
-      /* Looks like another copy of the SYN - retransmit our SYN-ACK */
-      tcp_rexmit(pcb);
-    }
-    break;
-  case CLOSE_WAIT:
-    /* FALLTHROUGH */
-  case ESTABLISHED:
-    tcp_receive(pcb);
-    if (recv_flags & TF_GOT_FIN) { /* passive close */
-      tcp_ack_now(pcb);
-      pcb->state = CLOSE_WAIT;
-    }
-    break;
-  case FIN_WAIT_1:
-    tcp_receive(pcb);
-    if (recv_flags & TF_GOT_FIN) {
-      if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
-        LWIP_DEBUGF(TCP_DEBUG,
-          ("TCP connection closed: FIN_WAIT_1 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
-        tcp_ack_now(pcb);
-        tcp_pcb_purge(pcb);
-        TCP_RMV_ACTIVE(pcb);
-        pcb->state = TIME_WAIT;
-        TCP_REG(&tcp_tw_pcbs, pcb);
-      } else {
-        tcp_ack_now(pcb);
-        pcb->state = CLOSING;
-      }
-    } else if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
-      pcb->state = FIN_WAIT_2;
-    }
-    break;
-  case FIN_WAIT_2:
-    tcp_receive(pcb);
-    if (recv_flags & TF_GOT_FIN) {
-      LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: FIN_WAIT_2 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
-      tcp_ack_now(pcb);
-      tcp_pcb_purge(pcb);
-      TCP_RMV_ACTIVE(pcb);
-      pcb->state = TIME_WAIT;
-      TCP_REG(&tcp_tw_pcbs, pcb);
-    }
-    break;
-  case CLOSING:
-    tcp_receive(pcb);
-    if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
-      LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: CLOSING %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
-      tcp_pcb_purge(pcb);
-      TCP_RMV_ACTIVE(pcb);
-      pcb->state = TIME_WAIT;
-      TCP_REG(&tcp_tw_pcbs, pcb);
-    }
-    break;
-  case LAST_ACK:
-    tcp_receive(pcb);
-    if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
-      LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: LAST_ACK %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
-      /* bugfix #21699: don't set pcb->state to CLOSED here or we risk leaking segments */
-      recv_flags |= TF_CLOSED;
-    }
-    break;
-  default:
-    break;
-  }
-  return ERR_OK;
-}
-
-#if TCP_QUEUE_OOSEQ
-/**
- * Insert segment into the list (segments covered with new one will be deleted)
- *
- * Called from tcp_receive()
- */
-static void
-tcp_oos_insert_segment(struct tcp_seg *cseg, struct tcp_seg *next)
-{
-  struct tcp_seg *old_seg;
-
-  if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
-    /* received segment overlaps all following segments */
-    tcp_segs_free(next);
-    next = NULL;
-  }
-  else {
-    /* delete some following segments
-       oos queue may have segments with FIN flag */
-    while (next &&
-           TCP_SEQ_GEQ((seqno + cseg->len),
-                      (next->tcphdr->seqno + next->len))) {
-      /* cseg with FIN already processed */
-      if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
-        TCPH_SET_FLAG(cseg->tcphdr, TCP_FIN);
-      }
-      old_seg = next;
-      next = next->next;
-      tcp_seg_free(old_seg);
-    }
-    if (next &&
-        TCP_SEQ_GT(seqno + cseg->len, next->tcphdr->seqno)) {
-      /* We need to trim the incoming segment. */
-      cseg->len = (u16_t)(next->tcphdr->seqno - seqno);
-      pbuf_realloc(cseg->p, cseg->len);
-    }
-  }
-  cseg->next = next;
-}
-#endif /* TCP_QUEUE_OOSEQ */
-
-/**
- * Called by tcp_process. Checks if the given segment is an ACK for outstanding
- * data, and if so frees the memory of the buffered data. Next, is places the
- * segment on any of the receive queues (pcb->recved or pcb->ooseq). If the segment
- * is buffered, the pbuf is referenced by pbuf_ref so that it will not be freed until
- * it has been removed from the buffer.
- *
- * If the incoming segment constitutes an ACK for a segment that was used for RTT
- * estimation, the RTT is estimated here as well.
- *
- * Called from tcp_process().
- */
-static void
-tcp_receive(struct tcp_pcb *pcb)
-{
-  struct tcp_seg *next;
-#if TCP_QUEUE_OOSEQ
-  struct tcp_seg *prev, *cseg;
-#endif /* TCP_QUEUE_OOSEQ */
-  struct pbuf *p;
-  s32_t off;
-  s16_t m;
-  u32_t right_wnd_edge;
-  u16_t new_tot_len;
-  int found_dupack = 0;
-#if TCP_OOSEQ_MAX_BYTES || TCP_OOSEQ_MAX_PBUFS
-  u32_t ooseq_blen;
-  u16_t ooseq_qlen;
-#endif /* TCP_OOSEQ_MAX_BYTES || TCP_OOSEQ_MAX_PBUFS */
-
-  LWIP_ASSERT("tcp_receive: wrong state", pcb->state >= ESTABLISHED);
-
-  if (flags & TCP_ACK) {
-    right_wnd_edge = pcb->snd_wnd + pcb->snd_wl2;
-
-    /* Update window. */
-    if (TCP_SEQ_LT(pcb->snd_wl1, seqno) ||
-       (pcb->snd_wl1 == seqno && TCP_SEQ_LT(pcb->snd_wl2, ackno)) ||
-       (pcb->snd_wl2 == ackno && tcphdr->wnd > pcb->snd_wnd)) {
-      pcb->snd_wnd = tcphdr->wnd;
-      /* keep track of the biggest window announced by the remote host to calculate
-         the maximum segment size */
-      if (pcb->snd_wnd_max < tcphdr->wnd) {
-        pcb->snd_wnd_max = tcphdr->wnd;
-      }
-      pcb->snd_wl1 = seqno;
-      pcb->snd_wl2 = ackno;
-      if (pcb->snd_wnd == 0) {
-        if (pcb->persist_backoff == 0) {
-          /* start persist timer */
-          pcb->persist_cnt = 0;
-          pcb->persist_backoff = 1;
-        }
-      } else if (pcb->persist_backoff > 0) {
-        /* stop persist timer */
-          pcb->persist_backoff = 0;
-      }
-      LWIP_DEBUGF(TCP_WND_DEBUG, ("tcp_receive: window update %"U16_F"\n", pcb->snd_wnd));
-#if TCP_WND_DEBUG
-    } else {
-      if (pcb->snd_wnd != tcphdr->wnd) {
-        LWIP_DEBUGF(TCP_WND_DEBUG,
-                    ("tcp_receive: no window update lastack %"U32_F" ackno %"
-                     U32_F" wl1 %"U32_F" seqno %"U32_F" wl2 %"U32_F"\n",
-                     pcb->lastack, ackno, pcb->snd_wl1, seqno, pcb->snd_wl2));
-      }
-#endif /* TCP_WND_DEBUG */
-    }
-
-    /* (From Stevens TCP/IP Illustrated Vol II, p970.) Its only a
-     * duplicate ack if:
-     * 1) It doesn't ACK new data
-     * 2) length of received packet is zero (i.e. no payload)
-     * 3) the advertised window hasn't changed
-     * 4) There is outstanding unacknowledged data (retransmission timer running)
-     * 5) The ACK is == biggest ACK sequence number so far seen (snd_una)
-     *
-     * If it passes all five, should process as a dupack:
-     * a) dupacks < 3: do nothing
-     * b) dupacks == 3: fast retransmit
-     * c) dupacks > 3: increase cwnd
-     *
-     * If it only passes 1-3, should reset dupack counter (and add to
-     * stats, which we don't do in lwIP)
-     *
-     * If it only passes 1, should reset dupack counter
-     *
-     */
-
-    /* Clause 1 */
-    if (TCP_SEQ_LEQ(ackno, pcb->lastack)) {
-      pcb->acked = 0;
-      /* Clause 2 */
-      if (tcplen == 0) {
-        /* Clause 3 */
-        if (pcb->snd_wl2 + pcb->snd_wnd == right_wnd_edge){
-          /* Clause 4 */
-          if (pcb->rtime >= 0) {
-            /* Clause 5 */
-            if (pcb->lastack == ackno) {
-              found_dupack = 1;
-              if ((u8_t)(pcb->dupacks + 1) > pcb->dupacks) {
-                ++pcb->dupacks;
-              }
-              if (pcb->dupacks > 3) {
-                /* Inflate the congestion window, but not if it means that
-                   the value overflows. */
-                if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
-                  pcb->cwnd += pcb->mss;
-                }
-              } else if (pcb->dupacks == 3) {
-                /* Do fast retransmit */
-                tcp_rexmit_fast(pcb);
-              }
-            }
-          }
-        }
-      }
-      /* If Clause (1) or more is true, but not a duplicate ack, reset
-       * count of consecutive duplicate acks */
-      if (!found_dupack) {
-        pcb->dupacks = 0;
-      }
-    } else if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)){
-      /* We come here when the ACK acknowledges new data. */
-
-      /* Reset the "IN Fast Retransmit" flag, since we are no longer
-         in fast retransmit. Also reset the congestion window to the
-         slow start threshold. */
-      if (pcb->flags & TF_INFR) {
-        pcb->flags &= ~TF_INFR;
-        pcb->cwnd = pcb->ssthresh;
-      }
-
-      /* Reset the number of retransmissions. */
-      pcb->nrtx = 0;
-
-      /* Reset the retransmission time-out. */
-      pcb->rto = (pcb->sa >> 3) + pcb->sv;
-
-      /* Update the send buffer space. Diff between the two can never exceed 64K? */
-      pcb->acked = (u16_t)(ackno - pcb->lastack);
-
-      pcb->snd_buf += pcb->acked;
-
-      /* Reset the fast retransmit variables. */
-      pcb->dupacks = 0;
-      pcb->lastack = ackno;
-
-      /* Update the congestion control variables (cwnd and
-         ssthresh). */
-      if (pcb->state >= ESTABLISHED) {
-        if (pcb->cwnd < pcb->ssthresh) {
-          if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
-            pcb->cwnd += pcb->mss;
-          }
-          LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: slow start cwnd %"U16_F"\n", pcb->cwnd));
-        } else {
-          u16_t new_cwnd = (pcb->cwnd + pcb->mss * pcb->mss / pcb->cwnd);
-          if (new_cwnd > pcb->cwnd) {
-            pcb->cwnd = new_cwnd;
-          }
-          LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: congestion avoidance cwnd %"U16_F"\n", pcb->cwnd));
-        }
-      }
-      LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: ACK for %"U32_F", unacked->seqno %"U32_F":%"U32_F"\n",
-                                    ackno,
-                                    pcb->unacked != NULL?
-                                    ntohl(pcb->unacked->tcphdr->seqno): 0,
-                                    pcb->unacked != NULL?
-                                    ntohl(pcb->unacked->tcphdr->seqno) + TCP_TCPLEN(pcb->unacked): 0));
-
-      /* Remove segment from the unacknowledged list if the incoming
-         ACK acknowlegdes them. */
-      while (pcb->unacked != NULL &&
-             TCP_SEQ_LEQ(ntohl(pcb->unacked->tcphdr->seqno) +
-                         TCP_TCPLEN(pcb->unacked), ackno)) {
-        LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unacked\n",
-                                      ntohl(pcb->unacked->tcphdr->seqno),
-                                      ntohl(pcb->unacked->tcphdr->seqno) +
-                                      TCP_TCPLEN(pcb->unacked)));
-
-        next = pcb->unacked;
-        pcb->unacked = pcb->unacked->next;
-
-        LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
-        LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
-        /* Prevent ACK for FIN to generate a sent event */
-        if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
-          pcb->acked--;
-        }
-
-        pcb->snd_queuelen -= pbuf_clen(next->p);
-        tcp_seg_free(next);
-
-        LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unacked)\n", (u16_t)pcb->snd_queuelen));
-        if (pcb->snd_queuelen != 0) {
-          LWIP_ASSERT("tcp_receive: valid queue length", pcb->unacked != NULL ||
-                      pcb->unsent != NULL);
-        }
-      }
-
-      /* If there's nothing left to acknowledge, stop the retransmit
-         timer, otherwise reset it to start again */
-      if(pcb->unacked == NULL)
-        pcb->rtime = -1;
-      else
-        pcb->rtime = 0;
-
-      pcb->polltmr = 0;
-    } else {
-      /* Fix bug bug #21582: out of sequence ACK, didn't really ack anything */
-      pcb->acked = 0;
-    }
-
-    /* We go through the ->unsent list to see if any of the segments
-       on the list are acknowledged by the ACK. This may seem
-       strange since an "unsent" segment shouldn't be acked. The
-       rationale is that lwIP puts all outstanding segments on the
-       ->unsent list after a retransmission, so these segments may
-       in fact have been sent once. */
-    while (pcb->unsent != NULL &&
-           TCP_SEQ_BETWEEN(ackno, ntohl(pcb->unsent->tcphdr->seqno) +
-                           TCP_TCPLEN(pcb->unsent), pcb->snd_nxt)) {
-      LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unsent\n",
-                                    ntohl(pcb->unsent->tcphdr->seqno), ntohl(pcb->unsent->tcphdr->seqno) +
-                                    TCP_TCPLEN(pcb->unsent)));
-
-      next = pcb->unsent;
-      pcb->unsent = pcb->unsent->next;
-#if TCP_OVERSIZE
-      if (pcb->unsent == NULL) {
-        pcb->unsent_oversize = 0;
-      }
-#endif /* TCP_OVERSIZE */
-      LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
-      LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
-      /* Prevent ACK for FIN to generate a sent event */
-      if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
-        pcb->acked--;
-      }
-      pcb->snd_queuelen -= pbuf_clen(next->p);
-      tcp_seg_free(next);
-      LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unsent)\n", (u16_t)pcb->snd_queuelen));
-      if (pcb->snd_queuelen != 0) {
-        LWIP_ASSERT("tcp_receive: valid queue length",
-          pcb->unacked != NULL || pcb->unsent != NULL);
-      }
-    }
-    /* End of ACK for new data processing. */
-
-    LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: pcb->rttest %"U32_F" rtseq %"U32_F" ackno %"U32_F"\n",
-                                pcb->rttest, pcb->rtseq, ackno));
-
-    /* RTT estimation calculations. This is done by checking if the
-       incoming segment acknowledges the segment we use to take a
-       round-trip time measurement. */
-    if (pcb->rttest && TCP_SEQ_LT(pcb->rtseq, ackno)) {
-      /* diff between this shouldn't exceed 32K since this are tcp timer ticks
-         and a round-trip shouldn't be that long... */
-      m = (s16_t)(tcp_ticks - pcb->rttest);
-
-      LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: experienced rtt %"U16_F" ticks (%"U16_F" msec).\n",
-                                  m, m * TCP_SLOW_INTERVAL));
-
-      /* This is taken directly from VJs original code in his paper */
-      m = m - (pcb->sa >> 3);
-      pcb->sa += m;
-      if (m < 0) {
-        m = -m;
-      }
-      m = m - (pcb->sv >> 2);
-      pcb->sv += m;
-      pcb->rto = (pcb->sa >> 3) + pcb->sv;
-
-      LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: RTO %"U16_F" (%"U16_F" milliseconds)\n",
-                                  pcb->rto, pcb->rto * TCP_SLOW_INTERVAL));
-
-      pcb->rttest = 0;
-    }
-  }
-
-  /* If the incoming segment contains data, we must process it
-     further unless the pcb already received a FIN.
-     (RFC 793, chapeter 3.9, "SEGMENT ARRIVES" in states CLOSE-WAIT, CLOSING,
-     LAST-ACK and TIME-WAIT: "Ignore the segment text.") */
-  if ((tcplen > 0) && (pcb->state < CLOSE_WAIT)) {
-    /* This code basically does three things:
-
-    +) If the incoming segment contains data that is the next
-    in-sequence data, this data is passed to the application. This
-    might involve trimming the first edge of the data. The rcv_nxt
-    variable and the advertised window are adjusted.
-
-    +) If the incoming segment has data that is above the next
-    sequence number expected (->rcv_nxt), the segment is placed on
-    the ->ooseq queue. This is done by finding the appropriate
-    place in the ->ooseq queue (which is ordered by sequence
-    number) and trim the segment in both ends if needed. An
-    immediate ACK is sent to indicate that we received an
-    out-of-sequence segment.
-
-    +) Finally, we check if the first segment on the ->ooseq queue
-    now is in sequence (i.e., if rcv_nxt >= ooseq->seqno). If
-    rcv_nxt > ooseq->seqno, we must trim the first edge of the
-    segment on ->ooseq before we adjust rcv_nxt. The data in the
-    segments that are now on sequence are chained onto the
-    incoming segment so that we only need to call the application
-    once.
-    */
-
-    /* First, we check if we must trim the first edge. We have to do
-       this if the sequence number of the incoming segment is less
-       than rcv_nxt, and the sequence number plus the length of the
-       segment is larger than rcv_nxt. */
-    /*    if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
-          if (TCP_SEQ_LT(pcb->rcv_nxt, seqno + tcplen)) {*/
-    if (TCP_SEQ_BETWEEN(pcb->rcv_nxt, seqno + 1, seqno + tcplen - 1)){
-      /* Trimming the first edge is done by pushing the payload
-         pointer in the pbuf downwards. This is somewhat tricky since
-         we do not want to discard the full contents of the pbuf up to
-         the new starting point of the data since we have to keep the
-         TCP header which is present in the first pbuf in the chain.
-
-         What is done is really quite a nasty hack: the first pbuf in
-         the pbuf chain is pointed to by inseg.p. Since we need to be
-         able to deallocate the whole pbuf, we cannot change this
-         inseg.p pointer to point to any of the later pbufs in the
-         chain. Instead, we point the ->payload pointer in the first
-         pbuf to data in one of the later pbufs. We also set the
-         inseg.data pointer to point to the right place. This way, the
-         ->p pointer will still point to the first pbuf, but the
-         ->p->payload pointer will point to data in another pbuf.
-
-         After we are done with adjusting the pbuf pointers we must
-         adjust the ->data pointer in the seg and the segment
-         length.*/
-
-      off = pcb->rcv_nxt - seqno;
-      p = inseg.p;
-      LWIP_ASSERT("inseg.p != NULL", inseg.p);
-      LWIP_ASSERT("insane offset!", (off < 0x7fff));
-      if (inseg.p->len < off) {
-        LWIP_ASSERT("pbuf too short!", (((s32_t)inseg.p->tot_len) >= off));
-        new_tot_len = (u16_t)(inseg.p->tot_len - off);
-        while (p->len < off) {
-          off -= p->len;
-          /* KJM following line changed (with addition of new_tot_len var)
-             to fix bug #9076
-             inseg.p->tot_len -= p->len; */
-          p->tot_len = new_tot_len;
-          p->len = 0;
-          p = p->next;
-        }
-        if(pbuf_header(p, (s16_t)-off)) {
-          /* Do we need to cope with this failing?  Assert for now */
-          LWIP_ASSERT("pbuf_header failed", 0);
-        }
-      } else {
-        if(pbuf_header(inseg.p, (s16_t)-off)) {
-          /* Do we need to cope with this failing?  Assert for now */
-          LWIP_ASSERT("pbuf_header failed", 0);
-        }
-      }
-      inseg.len -= (u16_t)(pcb->rcv_nxt - seqno);
-      inseg.tcphdr->seqno = seqno = pcb->rcv_nxt;
-    }
-    else {
-      if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
-        /* the whole segment is < rcv_nxt */
-        /* must be a duplicate of a packet that has already been correctly handled */
-
-        LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: duplicate seqno %"U32_F"\n", seqno));
-        tcp_ack_now(pcb);
-      }
-    }
-
-    /* The sequence number must be within the window (above rcv_nxt
-       and below rcv_nxt + rcv_wnd) in order to be further
-       processed. */
-    if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
-                        pcb->rcv_nxt + pcb->rcv_wnd - 1)){
-      if (pcb->rcv_nxt == seqno) {
-        /* The incoming segment is the next in sequence. We check if
-           we have to trim the end of the segment and update rcv_nxt
-           and pass the data to the application. */
-        tcplen = TCP_TCPLEN(&inseg);
-
-        if (tcplen > pcb->rcv_wnd) {
-          LWIP_DEBUGF(TCP_INPUT_DEBUG,
-                      ("tcp_receive: other end overran receive window"
-                       "seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
-                       seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
-          if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
-            /* Must remove the FIN from the header as we're trimming
-             * that byte of sequence-space from the packet */
-            TCPH_FLAGS_SET(inseg.tcphdr, TCPH_FLAGS(inseg.tcphdr) &~ TCP_FIN);
-          }
-          /* Adjust length of segment to fit in the window. */
-          inseg.len = pcb->rcv_wnd;
-          if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
-            inseg.len -= 1;
-          }
-          pbuf_realloc(inseg.p, inseg.len);
-          tcplen = TCP_TCPLEN(&inseg);
-          LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
-                      (seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
-        }
-#if TCP_QUEUE_OOSEQ
-        /* Received in-sequence data, adjust ooseq data if:
-           - FIN has been received or
-           - inseq overlaps with ooseq */
-        if (pcb->ooseq != NULL) {
-          if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
-            LWIP_DEBUGF(TCP_INPUT_DEBUG,
-                        ("tcp_receive: received in-order FIN, binning ooseq queue\n"));
-            /* Received in-order FIN means anything that was received
-             * out of order must now have been received in-order, so
-             * bin the ooseq queue */
-            while (pcb->ooseq != NULL) {
-              struct tcp_seg *old_ooseq = pcb->ooseq;
-              pcb->ooseq = pcb->ooseq->next;
-              tcp_seg_free(old_ooseq);
-            }
-          } else {
-            next = pcb->ooseq;
-            /* Remove all segments on ooseq that are covered by inseg already.
-             * FIN is copied from ooseq to inseg if present. */
-            while (next &&
-                   TCP_SEQ_GEQ(seqno + tcplen,
-                               next->tcphdr->seqno + next->len)) {
-              /* inseg cannot have FIN here (already processed above) */
-              if (TCPH_FLAGS(next->tcphdr) & TCP_FIN &&
-                  (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) == 0) {
-                TCPH_SET_FLAG(inseg.tcphdr, TCP_FIN);
-                tcplen = TCP_TCPLEN(&inseg);
-              }
-              prev = next;
-              next = next->next;
-              tcp_seg_free(prev);
-            }
-            /* Now trim right side of inseg if it overlaps with the first
-             * segment on ooseq */
-            if (next &&
-                TCP_SEQ_GT(seqno + tcplen,
-                           next->tcphdr->seqno)) {
-              /* inseg cannot have FIN here (already processed above) */
-              inseg.len = (u16_t)(next->tcphdr->seqno - seqno);
-              if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
-                inseg.len -= 1;
-              }
-              pbuf_realloc(inseg.p, inseg.len);
-              tcplen = TCP_TCPLEN(&inseg);
-              LWIP_ASSERT("tcp_receive: segment not trimmed correctly to ooseq queue\n",
-                          (seqno + tcplen) == next->tcphdr->seqno);
-            }
-            pcb->ooseq = next;
-          }
-        }
-#endif /* TCP_QUEUE_OOSEQ */
-
-        pcb->rcv_nxt = seqno + tcplen;
-
-        /* Update the receiver's (our) window. */
-        LWIP_ASSERT("tcp_receive: tcplen > rcv_wnd\n", pcb->rcv_wnd >= tcplen);
-        pcb->rcv_wnd -= tcplen;
-
-        tcp_update_rcv_ann_wnd(pcb);
-
-        /* If there is data in the segment, we make preparations to
-           pass this up to the application. The ->recv_data variable
-           is used for holding the pbuf that goes to the
-           application. The code for reassembling out-of-sequence data
-           chains its data on this pbuf as well.
-
-           If the segment was a FIN, we set the TF_GOT_FIN flag that will
-           be used to indicate to the application that the remote side has
-           closed its end of the connection. */
-        if (inseg.p->tot_len > 0) {
-          recv_data = inseg.p;
-          /* Since this pbuf now is the responsibility of the
-             application, we delete our reference to it so that we won't
-             (mistakingly) deallocate it. */
-          inseg.p = NULL;
-        }
-        if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
-          LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: received FIN.\n"));
-          recv_flags |= TF_GOT_FIN;
-        }
-
-#if TCP_QUEUE_OOSEQ
-        /* We now check if we have segments on the ->ooseq queue that
-           are now in sequence. */
-        while (pcb->ooseq != NULL &&
-               pcb->ooseq->tcphdr->seqno == pcb->rcv_nxt) {
-
-          cseg = pcb->ooseq;
-          seqno = pcb->ooseq->tcphdr->seqno;
-
-          pcb->rcv_nxt += TCP_TCPLEN(cseg);
-          LWIP_ASSERT("tcp_receive: ooseq tcplen > rcv_wnd\n",
-                      pcb->rcv_wnd >= TCP_TCPLEN(cseg));
-          pcb->rcv_wnd -= TCP_TCPLEN(cseg);
-
-          tcp_update_rcv_ann_wnd(pcb);
-
-          if (cseg->p->tot_len > 0) {
-            /* Chain this pbuf onto the pbuf that we will pass to
-               the application. */
-            if (recv_data) {
-              pbuf_cat(recv_data, cseg->p);
-            } else {
-              recv_data = cseg->p;
-            }
-            cseg->p = NULL;
-          }
-          if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
-            LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: dequeued FIN.\n"));
-            recv_flags |= TF_GOT_FIN;
-            if (pcb->state == ESTABLISHED) { /* force passive close or we can move to active close */
-              pcb->state = CLOSE_WAIT;
-            }
-          }
-
-          pcb->ooseq = cseg->next;
-          tcp_seg_free(cseg);
-        }
-#endif /* TCP_QUEUE_OOSEQ */
-
-
-        /* Acknowledge the segment(s). */
-        tcp_ack(pcb);
-
-      } else {
-        /* We get here if the incoming segment is out-of-sequence. */
-        tcp_send_empty_ack(pcb);
-#if TCP_QUEUE_OOSEQ
-        /* We queue the segment on the ->ooseq queue. */
-        if (pcb->ooseq == NULL) {
-          pcb->ooseq = tcp_seg_copy(&inseg);
-        } else {
-          /* If the queue is not empty, we walk through the queue and
-             try to find a place where the sequence number of the
-             incoming segment is between the sequence numbers of the
-             previous and the next segment on the ->ooseq queue. That is
-             the place where we put the incoming segment. If needed, we
-             trim the second edges of the previous and the incoming
-             segment so that it will fit into the sequence.
-
-             If the incoming segment has the same sequence number as a
-             segment on the ->ooseq queue, we discard the segment that
-             contains less data. */
-
-          prev = NULL;
-          for(next = pcb->ooseq; next != NULL; next = next->next) {
-            if (seqno == next->tcphdr->seqno) {
-              /* The sequence number of the incoming segment is the
-                 same as the sequence number of the segment on
-                 ->ooseq. We check the lengths to see which one to
-                 discard. */
-              if (inseg.len > next->len) {
-                /* The incoming segment is larger than the old
-                   segment. We replace some segments with the new
-                   one. */
-                cseg = tcp_seg_copy(&inseg);
-                if (cseg != NULL) {
-                  if (prev != NULL) {
-                    prev->next = cseg;
-                  } else {
-                    pcb->ooseq = cseg;
-                  }
-                  tcp_oos_insert_segment(cseg, next);
-                }
-                break;
-              } else {
-                /* Either the lenghts are the same or the incoming
-                   segment was smaller than the old one; in either
-                   case, we ditch the incoming segment. */
-                break;
-              }
-            } else {
-              if (prev == NULL) {
-                if (TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {
-                  /* The sequence number of the incoming segment is lower
-                     than the sequence number of the first segment on the
-                     queue. We put the incoming segment first on the
-                     queue. */
-                  cseg = tcp_seg_copy(&inseg);
-                  if (cseg != NULL) {
-                    pcb->ooseq = cseg;
-                    tcp_oos_insert_segment(cseg, next);
-                  }
-                  break;
-                }
-              } else {
-                /*if (TCP_SEQ_LT(prev->tcphdr->seqno, seqno) &&
-                  TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {*/
-                if (TCP_SEQ_BETWEEN(seqno, prev->tcphdr->seqno+1, next->tcphdr->seqno-1)) {
-                  /* The sequence number of the incoming segment is in
-                     between the sequence numbers of the previous and
-                     the next segment on ->ooseq. We trim trim the previous
-                     segment, delete next segments that included in received segment
-                     and trim received, if needed. */
-                  cseg = tcp_seg_copy(&inseg);
-                  if (cseg != NULL) {
-                    if (TCP_SEQ_GT(prev->tcphdr->seqno + prev->len, seqno)) {
-                      /* We need to trim the prev segment. */
-                      prev->len = (u16_t)(seqno - prev->tcphdr->seqno);
-                      pbuf_realloc(prev->p, prev->len);
-                    }
-                    prev->next = cseg;
-                    tcp_oos_insert_segment(cseg, next);
-                  }
-                  break;
-                }
-              }
-              /* If the "next" segment is the last segment on the
-                 ooseq queue, we add the incoming segment to the end
-                 of the list. */
-              if (next->next == NULL &&
-                  TCP_SEQ_GT(seqno, next->tcphdr->seqno)) {
-                if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
-                  /* segment "next" already contains all data */
-                  break;
-                }
-                next->next = tcp_seg_copy(&inseg);
-                if (next->next != NULL) {
-                  if (TCP_SEQ_GT(next->tcphdr->seqno + next->len, seqno)) {
-                    /* We need to trim the last segment. */
-                    next->len = (u16_t)(seqno - next->tcphdr->seqno);
-                    pbuf_realloc(next->p, next->len);
-                  }
-                  /* check if the remote side overruns our receive window */
-                  if ((u32_t)tcplen + seqno > pcb->rcv_nxt + (u32_t)pcb->rcv_wnd) {
-                    LWIP_DEBUGF(TCP_INPUT_DEBUG,
-                                ("tcp_receive: other end overran receive window"
-                                 "seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
-                                 seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
-                    if (TCPH_FLAGS(next->next->tcphdr) & TCP_FIN) {
-                      /* Must remove the FIN from the header as we're trimming
-                       * that byte of sequence-space from the packet */
-                      TCPH_FLAGS_SET(next->next->tcphdr, TCPH_FLAGS(next->next->tcphdr) &~ TCP_FIN);
-                    }
-                    /* Adjust length of segment to fit in the window. */
-                    next->next->len = pcb->rcv_nxt + pcb->rcv_wnd - seqno;
-                    pbuf_realloc(next->next->p, next->next->len);
-                    tcplen = TCP_TCPLEN(next->next);
-                    LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
-                                (seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
-                  }
-                }
-                break;
-              }
-            }
-            prev = next;
-          }
-        }
-#if TCP_OOSEQ_MAX_BYTES || TCP_OOSEQ_MAX_PBUFS
-        /* Check that the data on ooseq doesn't exceed one of the limits
-           and throw away everything above that limit. */
-        ooseq_blen = 0;
-        ooseq_qlen = 0;
-        prev = NULL;
-        for(next = pcb->ooseq; next != NULL; prev = next, next = next->next) {
-          struct pbuf *p = next->p;
-          ooseq_blen += p->tot_len;
-          ooseq_qlen += pbuf_clen(p);
-          if ((ooseq_blen > TCP_OOSEQ_MAX_BYTES) ||
-              (ooseq_qlen > TCP_OOSEQ_MAX_PBUFS)) {
-             /* too much ooseq data, dump this and everything after it */
-             tcp_segs_free(next);
-             if (prev == NULL) {
-               /* first ooseq segment is too much, dump the whole queue */
-               pcb->ooseq = NULL;
-             } else {
-               /* just dump 'next' and everything after it */
-               prev->next = NULL;
-             }
-             break;
-          }
-        }
-#endif /* TCP_OOSEQ_MAX_BYTES || TCP_OOSEQ_MAX_PBUFS */
-#endif /* TCP_QUEUE_OOSEQ */
-      }
-    } else {
-      /* The incoming segment is not withing the window. */
-      tcp_send_empty_ack(pcb);
-    }
-  } else {
-    /* Segments with length 0 is taken care of here. Segments that
-       fall out of the window are ACKed. */
-    /*if (TCP_SEQ_GT(pcb->rcv_nxt, seqno) ||
-      TCP_SEQ_GEQ(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) {*/
-    if(!TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt + pcb->rcv_wnd-1)){
-      tcp_ack_now(pcb);
-    }
-  }
-}
-
-/**
- * Parses the options contained in the incoming segment.
- *
- * Called from tcp_listen_input() and tcp_process().
- * Currently, only the MSS option is supported!
- *
- * @param pcb the tcp_pcb for which a segment arrived
- */
-static void
-tcp_parseopt(struct tcp_pcb *pcb)
-{
-  u16_t c, max_c;
-  u16_t mss;
-  u8_t *opts, opt;
-#if LWIP_TCP_TIMESTAMPS
-  u32_t tsval;
-#endif
-
-  opts = (u8_t *)tcphdr + TCP_HLEN;
-
-  /* Parse the TCP MSS option, if present. */
-  if(TCPH_HDRLEN(tcphdr) > 0x5) {
-    max_c = (TCPH_HDRLEN(tcphdr) - 5) << 2;
-    for (c = 0; c < max_c; ) {
-      opt = opts[c];
-      switch (opt) {
-      case 0x00:
-        /* End of options. */
-        LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: EOL\n"));
-        return;
-      case 0x01:
-        /* NOP option. */
-        ++c;
-        LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: NOP\n"));
-        break;
-      case 0x02:
-        LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: MSS\n"));
-        if (opts[c + 1] != 0x04 || c + 0x04 > max_c) {
-          /* Bad length */
-          LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
-          return;
-        }
-        /* An MSS option with the right option length. */
-        mss = (opts[c + 2] << 8) | opts[c + 3];
-        /* Limit the mss to the configured TCP_MSS and prevent division by zero */
-        pcb->mss = ((mss > TCP_MSS) || (mss == 0)) ? TCP_MSS : mss;
-        /* Advance to next option */
-        c += 0x04;
-        break;
-#if LWIP_TCP_TIMESTAMPS
-      case 0x08:
-        LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: TS\n"));
-        if (opts[c + 1] != 0x0A || c + 0x0A > max_c) {
-          /* Bad length */
-          LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
-          return;
-        }
-        /* TCP timestamp option with valid length */
-        tsval = (opts[c+2]) | (opts[c+3] << 8) |
-          (opts[c+4] << 16) | (opts[c+5] << 24);
-        if (flags & TCP_SYN) {
-          pcb->ts_recent = ntohl(tsval);
-          pcb->flags |= TF_TIMESTAMP;
-        } else if (TCP_SEQ_BETWEEN(pcb->ts_lastacksent, seqno, seqno+tcplen)) {
-          pcb->ts_recent = ntohl(tsval);
-        }
-        /* Advance to next option */
-        c += 0x0A;
-        break;
-#endif
-      default:
-        LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: other\n"));
-        if (opts[c + 1] == 0) {
-          LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
-          /* If the length field is zero, the options are malformed
-             and we don't process them further. */
-          return;
-        }
-        /* All other options have a length field, so that we easily
-           can skip past them. */
-        c += opts[c + 1];
-      }
-    }
-  }
-}
-
-#endif /* LWIP_TCP */