tcp_output.c

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	     pcb->unsent != NULL);
      
    }
#endif /* LWIP_DEBUG */
    DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue: %d (with mem err)\n", pcb->snd_queuelen));
  return ERR_MEM;
}
/*-----------------------------------------------------------------------------------*/
/* find out what we can send and send it */
err_t
tcp_output(struct tcp_pcb *pcb)
{
  struct pbuf *p;
  struct tcp_hdr *tcphdr;
  struct tcp_seg *seg, *useg;
  u32_t wnd;
#if TCP_CWND_DEBUG
  int i = 0;
#endif /* TCP_CWND_DEBUG */
  
  wnd = MIN(pcb->snd_wnd, pcb->cwnd);

  
  seg = pcb->unsent;

  if(pcb->flags & TF_ACK_NOW) {
    /* If no segments are enqueued but we should send an ACK, we
       construct the ACK and send it. */
    pcb->flags &= ~(TF_ACK_DELAY | TF_ACK_NOW);
    p = pbuf_alloc(PBUF_TRANSPORT, 0, PBUF_RAM);
    if(p == NULL) {
      DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_enqueue: (ACK) could not allocate pbuf\n"));
      return ERR_BUF;
    }
    DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_enqueue: sending ACK for %lu\n", pcb->rcv_nxt));    
    if(pbuf_header(p, TCP_HLEN)) {
      DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_enqueue: (ACK) no room for TCP header in pbuf.\n"));
      
#ifdef TCP_STATS
      ++stats.tcp.err;
#endif /* TCP_STATS */
      pbuf_free(p);
      return ERR_BUF;
    }
    
    tcphdr = p->payload;
    tcphdr->src = htons(pcb->local_port);
    tcphdr->dest = htons(pcb->remote_port);
    tcphdr->seqno = htonl(pcb->snd_nxt);
    tcphdr->ackno = htonl(pcb->rcv_nxt);
    TCPH_FLAGS_SET(tcphdr, TCP_ACK);
    tcphdr->wnd = htons(pcb->rcv_wnd);
    tcphdr->urgp = 0;
    TCPH_OFFSET_SET(tcphdr, 5 << 4);
    
    tcphdr->chksum = 0;
    tcphdr->chksum = inet_chksum_pseudo(p, &(pcb->local_ip), &(pcb->remote_ip),
					IP_PROTO_TCP, p->tot_len);

    ip_output(p, &(pcb->local_ip), &(pcb->remote_ip), TCP_TTL,
	      IP_PROTO_TCP);
    pbuf_free(p);

    return ERR_OK;
  } 
  
#if TCP_OUTPUT_DEBUG
  if(seg == NULL) {
    DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: nothing to send\n"));
  }
#endif /* TCP_OUTPUT_DEBUG */
#if TCP_CWND_DEBUG
  if(seg == NULL) {
    DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %lu, cwnd %lu, wnd %lu, seg == NULL, ack %lu\n",
                            pcb->snd_wnd, pcb->cwnd, wnd,
                            pcb->lastack));
  } else {
    DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %lu, cwnd %lu, wnd %lu, effwnd %lu, seq %lu, ack %lu\n",
                            pcb->snd_wnd, pcb->cwnd, wnd,
                            ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len,
                            ntohl(seg->tcphdr->seqno), pcb->lastack));
  }
#endif /* TCP_CWND_DEBUG */
  
  while(seg != NULL &&
	ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len <= wnd) {
    pcb->rtime = 0;
#if TCP_CWND_DEBUG
    DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %lu, cwnd %lu, wnd %lu, effwnd %lu, seq %lu, ack %lu, i%d\n",
                            pcb->snd_wnd, pcb->cwnd, wnd,
                            ntohl(seg->tcphdr->seqno) + seg->len -
                            pcb->lastack,
                            ntohl(seg->tcphdr->seqno), pcb->lastack, i));
    ++i;
#endif /* TCP_CWND_DEBUG */

    pcb->unsent = seg->next;
    
    
    if(pcb->state != SYN_SENT) {
      TCPH_FLAGS_SET(seg->tcphdr, TCPH_FLAGS(seg->tcphdr) | TCP_ACK);
      pcb->flags &= ~(TF_ACK_DELAY | TF_ACK_NOW);
    }
    
    tcp_output_segment(seg, pcb);
    pcb->snd_nxt = ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg);
    if(TCP_SEQ_LT(pcb->snd_max, pcb->snd_nxt)) {
      pcb->snd_max = pcb->snd_nxt;
    }
    /* put segment on unacknowledged list if length > 0 */
    if(TCP_TCPLEN(seg) > 0) {
      seg->next = NULL;
      if(pcb->unacked == NULL) {
        pcb->unacked = seg;
      } else {
        for(useg = pcb->unacked; useg->next != NULL; useg = useg->next);
        useg->next = seg;
      }
      /*      seg->rtime = 0;*/      
    } else {
      tcp_seg_free(seg);
    }
    seg = pcb->unsent;
  }  
  return ERR_OK;
}
/*-----------------------------------------------------------------------------------*/
static void
tcp_output_segment(struct tcp_seg *seg, struct tcp_pcb *pcb)
{
  u16_t len, tot_len;
  struct netif *netif;

  /* The TCP header has already been constructed, but the ackno and
   wnd fields remain. */
  seg->tcphdr->ackno = htonl(pcb->rcv_nxt);

  /* silly window avoidance */
  if(pcb->rcv_wnd < pcb->mss) {
    seg->tcphdr->wnd = 0;
  } else {
    seg->tcphdr->wnd = htons(pcb->rcv_wnd);
  }

  /* If we don't have a local IP address, we get one by
     calling ip_route(). */
  if(ip_addr_isany(&(pcb->local_ip))) {
    netif = ip_route(&(pcb->remote_ip));
    if(netif == NULL) {
      return;
    }
    ip_addr_set(&(pcb->local_ip), &(netif->ip_addr));
  }

  pcb->rtime = 0;
  
  if(pcb->rttest == 0) {
    pcb->rttest = tcp_ticks;
    pcb->rtseq = ntohl(seg->tcphdr->seqno);

    DEBUGF(TCP_RTO_DEBUG, ("tcp_output_segment: rtseq %lu\n", pcb->rtseq));
  }
  DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output_segment: %lu:%lu\n",
			    htonl(seg->tcphdr->seqno), htonl(seg->tcphdr->seqno) +
			    seg->len));

  seg->tcphdr->chksum = 0;
  seg->tcphdr->chksum = inet_chksum_pseudo(seg->p,
					   &(pcb->local_ip),
					   &(pcb->remote_ip),
					   IP_PROTO_TCP, seg->p->tot_len);
#ifdef TCP_STATS
  ++stats.tcp.xmit;
#endif /* TCP_STATS */

  len = seg->p->len;
  tot_len = seg->p->tot_len;
  ip_output(seg->p, &(pcb->local_ip), &(pcb->remote_ip), TCP_TTL,
	    IP_PROTO_TCP);
  seg->p->len = len;
  seg->p->tot_len = tot_len;
  seg->p->payload = seg->tcphdr;

}
/*-----------------------------------------------------------------------------------*/
void
tcp_rexmit_seg(struct tcp_pcb *pcb, struct tcp_seg *seg)
{
  u32_t wnd;
  u16_t len, tot_len;
  struct netif *netif;
  
  DEBUGF(TCP_REXMIT_DEBUG, ("tcp_rexmit_seg: skickar %ld:%ld\n",
			    ntohl(seg->tcphdr->seqno),
			    ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg)));

  wnd = MIN(pcb->snd_wnd, pcb->cwnd);
  
  if(ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len <= wnd) {

    /* Count the number of retranmissions. */
    ++pcb->nrtx;
    
    if((netif = ip_route((struct ip_addr *)&(pcb->remote_ip))) == NULL) {
      DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_rexmit_segment: No route to 0x%lx\n", pcb->remote_ip.addr));
#ifdef TCP_STATS
      ++stats.tcp.rterr;
#endif /* TCP_STATS */
      return;
    }

    seg->tcphdr->ackno = htonl(pcb->rcv_nxt);
    seg->tcphdr->wnd = htons(pcb->rcv_wnd);

    /* Recalculate checksum. */
    seg->tcphdr->chksum = 0;
    seg->tcphdr->chksum = inet_chksum_pseudo(seg->p,
                                             &(pcb->local_ip),
                                             &(pcb->remote_ip),
                                             IP_PROTO_TCP, seg->p->tot_len);
    
    len = seg->p->len;
    tot_len = seg->p->tot_len;
    pbuf_header(seg->p, IP_HLEN);
    ip_output_if(seg->p, NULL, IP_HDRINCL, TCP_TTL, IP_PROTO_TCP, netif);
    seg->p->len = len;
    seg->p->tot_len = tot_len;
    seg->p->payload = seg->tcphdr;

#ifdef TCP_STATS
    ++stats.tcp.xmit;
    ++stats.tcp.rexmit;
#endif /* TCP_STATS */

    pcb->rtime = 0;
    
    /* Don't take any rtt measurements after retransmitting. */    
    pcb->rttest = 0;
  } else {
    DEBUGF(TCP_REXMIT_DEBUG, ("tcp_rexmit_seg: no room in window %lu to send %lu (ack %lu)\n",
                              wnd, ntohl(seg->tcphdr->seqno), pcb->lastack));
  }
}
/*-----------------------------------------------------------------------------------*/
void
tcp_rst(u32_t seqno, u32_t ackno,
	struct ip_addr *local_ip, struct ip_addr *remote_ip,
	u16_t local_port, u16_t remote_port)
{
  struct pbuf *p;
  struct tcp_hdr *tcphdr;
  p = pbuf_alloc(PBUF_TRANSPORT, 0, PBUF_RAM);
  if(p == NULL) {
#if MEM_RECLAIM
    mem_reclaim(sizeof(struct pbuf));
    p = pbuf_alloc(PBUF_TRANSPORT, 0, PBUF_RAM);
#endif /* MEM_RECLAIM */    
    if(p == NULL) {
      DEBUGF(TCP_DEBUG, ("tcp_rst: could not allocate memory for pbuf\n"));
      return;
    }
  }
  if(pbuf_header(p, TCP_HLEN)) {
    DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_send_data: no room for TCP header in pbuf.\n"));

#ifdef TCP_STATS
    ++stats.tcp.err;
#endif /* TCP_STATS */
    return;
  }

  tcphdr = p->payload;
  tcphdr->src = htons(local_port);
  tcphdr->dest = htons(remote_port);
  tcphdr->seqno = htonl(seqno);
  tcphdr->ackno = htonl(ackno);
  TCPH_FLAGS_SET(tcphdr, TCP_RST | TCP_ACK);
  tcphdr->wnd = 0;
  tcphdr->urgp = 0;
  TCPH_OFFSET_SET(tcphdr, 5 << 4);
  
  tcphdr->chksum = 0;
  tcphdr->chksum = inet_chksum_pseudo(p, local_ip, remote_ip,
				      IP_PROTO_TCP, p->tot_len);

#ifdef TCP_STATS
  ++stats.tcp.xmit;
#endif /* TCP_STATS */
  ip_output(p, local_ip, remote_ip, TCP_TTL, IP_PROTO_TCP);
  pbuf_free(p);
  DEBUGF(TCP_RST_DEBUG, ("tcp_rst: seqno %lu ackno %lu.\n", seqno, ackno));
}
/*-----------------------------------------------------------------------------------*/