Mentioned adapted TCP behaviour; send ACK even if one was pending, iff rcv_wnd is above threshold.

- Add code to tcp_recved() to send an ACK (window update)
immediately, even if one is already pending, if the rcv_wnd is above a
threshold (currently TCP_WND/2)
 - This avoids waiting for a timer to expire to send a delayed ACK in
order to open the window if the stack is only receiving data.

CHANGELOG

@@ -9,6 +9,48 @@ HISTORY
 
 (HEAD)
 
+(STABLE-1_1_0-RC1)
+
+  2004-10-16 Kieran Mansley <kjm25@cam.ac.uk>
+  * tcp.c Add code to tcp_recved() to send an ACK (window update) immediately,
+	even if one is already pending, if the rcv_wnd is above a threshold
+	(currently TCP_WND/2). This avoids waiting for a timer to expire to send a
+	delayed ACK in order to open the window if the stack is only receiving data.
+
+  2004-09-12 Kieran Mansley <kjm25@cam.ac.uk>
+  * tcp*.* Retransmit time-out handling improvement by Sam Jansen.
+
+  2004-08-20 Tony Mountifield <tony@softins.co.uk>
+  * etharp.c Make sure the first pbuf queued on an ARP entry
+    is properly ref counted.
+
+  2004-07-27 Tony Mountifield <tony@softins.co.uk>
+  * debug.h Added (int) cast in LWIP_DEBUGF() to avoid compiler
+    warnings about comparison.
+  * pbuf.c Stopped compiler complaining of empty if statement
+    when LWIP_DEBUGF() empty.  Closed an unclosed comment.
+  * tcp.c Stopped compiler complaining of empty if statement
+    when LWIP_DEBUGF() empty.
+  * ip.h Corrected IPH_TOS() macro: returns a byte, so doesn't need htons().
+  * inet.c Added a couple of casts to quiet the compiler.
+    No need to test isascii(c) before isdigit(c) or isxdigit(c).
+
+  2004-07-22 Tony Mountifield <tony@softins.co.uk>
+  * inet.c Made data types consistent in inet_ntoa().
+    Added casts for return values of checksum routines, to pacify compiler.
+  * ip_frag.c, tcp_out.c, sockets.c, pbuf.c
+    Small corrections to some debugging statements, to pacify compiler.
+
+  2004-07-21 Tony Mountifield <tony@softins.co.uk>
+  * etharp.c Removed spurious semicolon and added missing end-of-comment.
+  * ethernetif.c Updated low_level_output() to match prototype for
+    netif->linkoutput and changed low_level_input() similarly for consistency.
+  * api_msg.c Changed recv_raw() from int to u8_t, to match prototype
+    of raw_recv() in raw.h and so avoid compiler error.
+  * sockets.c Added trivial (int) cast to keep compiler happier.
+  * ip.c, netif.c Changed debug statements to use the tidier ip4_addrN() macros.
+
+  
 (STABLE-1_0_0)
 
   ++ Changes:

doc/savannah.txt

@@ -115,40 +115,16 @@ tar czvf lwip-0.6.3.tar.gz lwip-0.6.3
 tar cjvf lwip-0.6.3.tar.bz2 lwip-0.6.3
 zip -r lwip-0.6.3.zip lwip-0.6.3
 
-First, make a local release directory to work in, I use "lwip-releases":
+Now, sign the archives with a detached GPG binary signature as follows:
 
-mkdir lwip-releases
-cd lwip-releases
+gpg -b lwip-0.6.3.tar.gz
+gpg -b lwip-0.6.3.tar.bz2
+gpg -b lwip-0.6.3.zip
 
-Now, make a new release by creating a new directory for it (these are
-Savannah conventions so that it shows up in the Files list real nice):
+Upload these files using anonymous FTP:
+ncftp ftp://savannah.gnu.org/incoming/savannah/lwip
 
-mkdir stable.pkg
-mkdir stable.pkg 0.6.3
-
-We can now copy the tar archive we made earlier into the release directory:
-
-cp ../../../lwip-0.6.3.tar.gz .
-
-Finally, synchronize this directory upwards to Savannah:
-
-rsync -n -e "ssh -1" -t -u -v -r *.pkg likewise@savannah.nongnu.org:/upload/lwip
-
-This does a "dry run": no files are modified! After you have confirmed that
-this is what you intended to do, remove "-n" and actually synchronize for
-real. The release should now be available here:
-
-http://savannah.nongnu.org/files/?group=lwip
-
----
-Explanation of rsync options used:
-
--t: preserve file timestamps
--u: do not overwrite existing files, unless they are older
--v: be verbose (long format file attributes)
--r: recurse into directories
--n: dry-run, do not modify anything. 
----
+ncftp>mput *0.6.3.*
 
 Additionally, you may post a news item on Savannah, like this:
 

src/api/api_lib.c

@@ -280,9 +280,10 @@ netconn_delete(struct netconn *conn)
   if (conn->recvmbox != SYS_MBOX_NULL) {
     while (sys_arch_mbox_fetch(conn->recvmbox, &mem, 1) != SYS_ARCH_TIMEOUT) {
       if (conn->type == NETCONN_TCP) {
-  pbuf_free((struct pbuf *)mem);
+        if(mem != NULL)
+          pbuf_free((struct pbuf *)mem);
       } else {
-  netbuf_delete((struct netbuf *)mem);
+        netbuf_delete((struct netbuf *)mem);
       }
     }
     sys_mbox_free(conn->recvmbox);

src/core/dhcp.c

@@ -85,7 +85,8 @@
 #if LWIP_DHCP /* don't build if not configured for use in lwipopt.h */
 
 /** global transaction identifier, must be
- *  unique for each DHCP request. */
+ *  unique for each DHCP request. We simply increment, starting
+ *  with this value (easy to match with a packet analyzer) */
 static u32_t xid = 0xABCD0000;
 
 /** DHCP client state machine functions */
@@ -805,6 +806,8 @@ static void dhcp_bind(struct netif *netif)
   netif_set_netmask(netif, &sn_mask);
   LWIP_DEBUGF(DHCP_DEBUG | DBG_STATE, ("dhcp_bind(): GW: 0x%08lx\n", gw_addr.addr));
   netif_set_gw(netif, &gw_addr);
+  /* bring the interface up */
+  netif_set_up(netif);
   /* netif is now bound to DHCP leased address */
   dhcp_set_state(dhcp, DHCP_BOUND);
 }
@@ -960,10 +963,13 @@ static err_t dhcp_release(struct netif *netif)
   msecs = dhcp->tries < 10 ? dhcp->tries * 1000 : 10 * 1000;
   dhcp->request_timeout = (msecs + DHCP_FINE_TIMER_MSECS - 1) / DHCP_FINE_TIMER_MSECS;
   LWIP_DEBUGF(DHCP_DEBUG | DBG_TRACE | DBG_STATE, ("dhcp_release(): set request timeout %u msecs\n", msecs));
+  /* bring the interface down */
+  netif_set_down(netif);
   /* remove IP address from interface */
   netif_set_ipaddr(netif, IP_ADDR_ANY);
   netif_set_gw(netif, IP_ADDR_ANY);
   netif_set_netmask(netif, IP_ADDR_ANY);
+  
   /* TODO: netif_down(netif); */
   return result;
 }

src/core/inet.c

@@ -46,10 +46,21 @@
 #include "lwip/def.h"
 #include "lwip/inet.h"
 
+#include "lwip/sys.h"
 
+/* This is a reference implementation of the checksum algorithm
 
+ - it may not work on all architectures, and all processors, particularly
+   if they have issues with alignment and 16 bit access.
+
+ - in this case you will need to port it to your architecture and 
+   #define LWIP_CHKSUM <your_checksum_routine> 
+   in your sys_arch.h
+*/
+#ifndef LWIP_CHKSUM
+#define LWIP_CHKSUM lwip_standard_chksum
 static u16_t
-lwip_chksum(void *dataptr, int len)
+lwip_standard_chksum(void *dataptr, int len)
 {
   u32_t acc;
 
@@ -75,6 +86,7 @@ lwip_chksum(void *dataptr, int len)
 
   return (u16_t)acc;
 }
+#endif
 
 /* inet_chksum_pseudo:
  *
@@ -96,7 +108,7 @@ inet_chksum_pseudo(struct pbuf *p,
   for(q = p; q != NULL; q = q->next) {
     LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): checksumming pbuf %p (has next %p) \n",
       (void *)q, (void *)q->next));
-    acc += lwip_chksum(q->payload, q->len);
+    acc += LWIP_CHKSUM(q->payload, q->len);
     /*LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): unwrapped lwip_chksum()=%lx \n", acc));*/
     while (acc >> 16) {
       acc = (acc & 0xffffUL) + (acc >> 16);
@@ -136,7 +148,7 @@ inet_chksum(void *dataptr, u16_t len)
 {
   u32_t acc;
 
-  acc = lwip_chksum(dataptr, len);
+  acc = LWIP_CHKSUM(dataptr, len);
   while (acc >> 16) {
     acc = (acc & 0xffff) + (acc >> 16);
   }
@@ -153,7 +165,7 @@ inet_chksum_pbuf(struct pbuf *p)
   acc = 0;
   swapped = 0;
   for(q = p; q != NULL; q = q->next) {
-    acc += lwip_chksum(q->payload, q->len);
+    acc += LWIP_CHKSUM(q->payload, q->len);
     while (acc >> 16) {
       acc = (acc & 0xffffUL) + (acc >> 16);
     }

src/core/tcp.c

@@ -444,6 +444,16 @@ tcp_recved(struct tcp_pcb *pcb, u16_t len)
      * continue to transmit.
      */
     tcp_ack(pcb);
+  } 
+  else if (pcb->flags & TF_ACK_DELAY && pcb->rcv_wnd >= TCP_WND/2) {
+    /* If we can send a window update such that there is a full
+     * segment available in the window, do so now.  This is sort of
+     * nagle-like in its goals, and tries to hit a compromise between
+     * sending acks each time the window is updated, and only sending
+     * window updates when a timer expires.  The "threshold" used
+     * above (currently TCP_WND/2) can be tuned to be more or less
+     * aggressive  */
+    tcp_ack_now(pcb);
   }
 
   LWIP_DEBUGF(TCP_DEBUG, ("tcp_recved: recveived %u bytes, wnd %u (%u).\n",
@@ -590,7 +600,6 @@ tcp_slowtmr(void)
         if (pcb->state != SYN_SENT) {
           pcb->rto = ((pcb->sa >> 3) + pcb->sv) << tcp_backoff[pcb->nrtx];
         }
-        tcp_rexmit(pcb);
         /* Reduce congestion window and ssthresh. */
         eff_wnd = LWIP_MIN(pcb->cwnd, pcb->snd_wnd);
         pcb->ssthresh = eff_wnd >> 1;
@@ -600,7 +609,10 @@ tcp_slowtmr(void)
         pcb->cwnd = pcb->mss;
         LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_slowtmr: cwnd %u ssthresh %u\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) {

src/core/tcp_in.c

@@ -506,9 +506,11 @@ tcp_process(struct tcp_pcb *pcb)
   acceptable = 1;
       }
     } else {
-      if (TCP_SEQ_GEQ(seqno, pcb->rcv_nxt) &&
-   TCP_SEQ_LEQ(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) {
-  acceptable = 1;
+      /*if (TCP_SEQ_GEQ(seqno, pcb->rcv_nxt) &&
+          TCP_SEQ_LEQ(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) {
+      */
+      if(TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt+pcb->rcv_wnd)){
+        acceptable = 1;
       }
     }
 
@@ -562,8 +564,9 @@ tcp_process(struct tcp_pcb *pcb)
   case SYN_RCVD:
     if (flags & TCP_ACK &&
        !(flags & TCP_RST)) {
-      if (TCP_SEQ_LT(pcb->lastack, ackno) &&
-          TCP_SEQ_LEQ(ackno, pcb->snd_nxt)) {
+      /*if (TCP_SEQ_LT(pcb->lastack, ackno) &&
+        TCP_SEQ_LEQ(ackno, pcb->snd_nxt)) { */
+      if(TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)){
         pcb->state = ESTABLISHED;
         LWIP_DEBUGF(TCP_DEBUG, ("TCP connection established %u -> %u.\n", inseg.tcphdr->src, inseg.tcphdr->dest));
 #if LWIP_CALLBACK_API
@@ -732,8 +735,10 @@ tcp_receive(struct tcp_pcb *pcb)
         LWIP_DEBUGF(TCP_FR_DEBUG, ("tcp_receive: dupack averted %lu %lu\n",
                                    pcb->snd_wl1 + pcb->snd_wnd, right_wnd_edge));
       }
-    } else if (TCP_SEQ_LT(pcb->lastack, ackno) &&
-               TCP_SEQ_LEQ(ackno, pcb->snd_max)) {
+    } else
+      /*if (TCP_SEQ_LT(pcb->lastack, ackno) &&
+        TCP_SEQ_LEQ(ackno, pcb->snd_max)) { */
+      if(TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_max)){
       /* We come here when the ACK acknowledges new data. */
       
       /* Reset the "IN Fast Retransmit" flag, since we are no longer
@@ -813,17 +818,14 @@ tcp_receive(struct tcp_pcb *pcb)
        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. */
-    /* KJM 13th July 2004
-       I don't think is is necessary as we no longer move all unacked
-       segments on the unsent queue when performing retransmit */
-#if 0
     while (pcb->unsent != NULL &&
-      TCP_SEQ_LEQ(ntohl(pcb->unsent->tcphdr->seqno) + TCP_TCPLEN(pcb->unsent),
-      ackno) &&
-      TCP_SEQ_LEQ(ackno, pcb->snd_max)) {
+           /*TCP_SEQ_LEQ(ntohl(pcb->unsent->tcphdr->seqno) + TCP_TCPLEN(pcb->unsent), ackno) &&
+             TCP_SEQ_LEQ(ackno, pcb->snd_max)*/
+           TCP_SEQ_BETWEEN(ackno, ntohl(pcb->unsent->tcphdr->seqno) + TCP_TCPLEN(pcb->unsent), pcb->snd_max)
+           ) {
       LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %lu:%lu from pcb->unsent\n",
-        ntohl(pcb->unsent->tcphdr->seqno), ntohl(pcb->unsent->tcphdr->seqno) +
-        TCP_TCPLEN(pcb->unsent)));
+                                    ntohl(pcb->unsent->tcphdr->seqno), ntohl(pcb->unsent->tcphdr->seqno) +
+                                    TCP_TCPLEN(pcb->unsent)));
 
       next = pcb->unsent;
       pcb->unsent = pcb->unsent->next;
@@ -840,7 +842,6 @@ tcp_receive(struct tcp_pcb *pcb)
         pcb->snd_nxt = htonl(pcb->unsent->tcphdr->seqno);
       }
     }
-#endif
     /* End of ACK for new data processing. */
 
     LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: pcb->rttest %u rtseq %lu ackno %lu\n",
@@ -903,55 +904,57 @@ tcp_receive(struct tcp_pcb *pcb)
        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)) {
-        /* 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;
-        if (inseg.p->len < off) {
-          new_tot_len = 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;
-          }
-          pbuf_header(p, -off);
-        } else {
-          pbuf_header(inseg.p, -off);
+    /*    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;
+      if (inseg.p->len < off) {
+        new_tot_len = 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;
         }
-        /* KJM following line changed to use p->payload rather than inseg->p->payload
-           to fix bug #9076 */
-        inseg.dataptr = p->payload;
-        inseg.len -= pcb->rcv_nxt - seqno;
-        inseg.tcphdr->seqno = seqno = pcb->rcv_nxt;
+        pbuf_header(p, -off);
+      } else {
+        pbuf_header(inseg.p, -off);
       }
-      else{
+      /* KJM following line changed to use p->payload rather than inseg->p->payload
+         to fix bug #9076 */
+      inseg.dataptr = p->payload;
+      inseg.len -= 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 %lu\n", seqno));
         tcp_ack_now(pcb);
       }
@@ -960,8 +963,9 @@ tcp_receive(struct tcp_pcb *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_GEQ(seqno, pcb->rcv_nxt) &&
-        TCP_SEQ_LT(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) {
+    /*if (TCP_SEQ_GEQ(seqno, pcb->rcv_nxt) &&
+      TCP_SEQ_LT(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) {*/
+    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
@@ -1115,8 +1119,10 @@ tcp_receive(struct tcp_pcb *pcb)
                   }
                   break;
                 }
-              } else if (TCP_SEQ_LT(prev->tcphdr->seqno, seqno) &&
-                         TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {
+              } 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 and insert the
@@ -1162,12 +1168,19 @@ tcp_receive(struct tcp_pcb *pcb)
 #endif /* TCP_QUEUE_OOSEQ */
 
       }
+    } else {
+      /*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);
+      }
     }
   } 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_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);
     }
   }
@@ -1201,7 +1214,7 @@ tcp_parseopt(struct tcp_pcb *pcb)
         ++c;
         /* NOP option. */
       } else if (opt == 0x02 &&
-                opts[c + 1] == 0x04) {
+        opts[c + 1] == 0x04) {
         /* An MSS option with the right option length. */
         mss = (opts[c + 2] << 8) | opts[c + 3];
         pcb->mss = mss > TCP_MSS? TCP_MSS: mss;

src/core/tcp_out.c

@@ -462,8 +462,16 @@ tcp_output(struct tcp_pcb *pcb)
         pcb->unacked = seg;
         useg = seg;
       } else {
-        useg->next = seg;
-        useg = useg->next;
+        /* In the case of fast retransmit, the packet should not go to the end
+         * of the unacked queue, but rather at the start. We need to check for
+         * this case. -STJ Jul 27, 2004 */
+        if (TCP_SEQ_LT(ntohl(seg->tcphdr->seqno), ntohl(useg->tcphdr->seqno))){
+          seg->next = pcb->unacked;
+          pcb->unacked = seg;
+        } else {
+          useg->next = seg;
+          useg = useg->next;
+        }
       }
     } else {
       tcp_seg_free(seg);
@@ -568,6 +576,33 @@ tcp_rst(u32_t seqno, u32_t ackno,
   LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_rst: seqno %lu ackno %lu.\n", seqno, ackno));
 }
 
+void
+tcp_rexmit_rto(struct tcp_pcb *pcb)
+{
+  struct tcp_seg *seg;
+
+  if (pcb->unacked == NULL) {
+    return;
+  }
+
+  /* Move all unacked segments to the unsent queue. */
+  for (seg = pcb->unacked; seg->next != NULL; seg = seg->next);
+  seg->next = pcb->unsent;
+  pcb->unsent = pcb->unacked;
+  pcb->unacked = NULL;
+
+  pcb->snd_nxt = ntohl(pcb->unsent->tcphdr->seqno);
+
+  ++pcb->nrtx;
+
+  /* Don't take any rtt measurements after retransmitting. */
+  pcb->rttest = 0;
+
+  /* Do the actual retransmission. */
+  tcp_output(pcb);
+
+}
+
 void
 tcp_rexmit(struct tcp_pcb *pcb)
 {
@@ -595,6 +630,7 @@ tcp_rexmit(struct tcp_pcb *pcb)
 
 }
 
+
 void
 tcp_keepalive(struct tcp_pcb *pcb)
 {

src/include/lwip/opt.h

@@ -146,10 +146,10 @@ a lot of data that needs to be copied, this should be set high. */
 #endif
 
 /* PBUF_LINK_HLEN: the number of bytes that should be allocated for a
-   link level header. */
+   link level header. Defaults to 14 for Ethernet. */
 
 #ifndef PBUF_LINK_HLEN
-#define PBUF_LINK_HLEN                  0
+#define PBUF_LINK_HLEN                  14
 #endif
 
 

src/include/lwip/tcp.h

@@ -105,6 +105,7 @@ void             tcp_input   (struct pbuf *p, struct netif *inp);
 /* Used within the TCP code only: */
 err_t            tcp_output  (struct tcp_pcb *pcb);
 void             tcp_rexmit  (struct tcp_pcb *pcb);
+void             tcp_rexmit_rto  (struct tcp_pcb *pcb);
 
 
 
@@ -112,7 +113,11 @@ void             tcp_rexmit  (struct tcp_pcb *pcb);
 #define TCP_SEQ_LEQ(a,b)    ((s32_t)((a)-(b)) <= 0)
 #define TCP_SEQ_GT(a,b)     ((s32_t)((a)-(b)) > 0)
 #define TCP_SEQ_GEQ(a,b)    ((s32_t)((a)-(b)) >= 0)
-
+/* is b<=a<=c? */
+#if 0 /* see bug #10548 */
+#define TCP_SEQ_BETWEEN(a,b,c) ((c)-(b) >= (a)-(b))
+#endif
+#define TCP_SEQ_BETWEEN(a,b,c) (TCP_SEQ_GEQ(a,b) && TCP_SEQ_LEQ(a,c))
 #define TCP_FIN 0x01U
 #define TCP_SYN 0x02U
 #define TCP_RST 0x04U
@@ -375,7 +380,7 @@ err_t lwip_tcp_event(void *arg, struct tcp_pcb *pcb,
 #define TCP_EVENT_RECV(pcb,p,err,ret) \
                         if((pcb)->recv != NULL) \
                         { ret = (pcb)->recv((pcb)->callback_arg,(pcb),(p),(err)); } else { \
-            pbuf_free(p); }
+                          if (p) pbuf_free(p); }
 #define TCP_EVENT_CONNECTED(pcb,err,ret) \
                         if((pcb)->connected != NULL) \
                         (ret = (pcb)->connected((pcb)->callback_arg,(pcb),(err)))

src/include/netif/etharp.h

@@ -52,7 +52,13 @@ struct eth_addr {
   PACK_STRUCT_FIELD(u8_t addr[6]);
 } PACK_STRUCT_STRUCT;
 PACK_STRUCT_END
+#ifdef PACK_STRUCT_USE_INCLUDES
+#  include "arch/epstruct.h"
+#endif
 
+#ifdef PACK_STRUCT_USE_INCLUDES
+#  include "arch/bpstruct.h"
+#endif
 PACK_STRUCT_BEGIN
 struct eth_hdr {
 #if ETH_PAD_SIZE
@@ -63,7 +69,13 @@ struct eth_hdr {
   PACK_STRUCT_FIELD(u16_t type);
 } PACK_STRUCT_STRUCT;
 PACK_STRUCT_END
+#ifdef PACK_STRUCT_USE_INCLUDES
+#  include "arch/epstruct.h"
+#endif
 
+#ifdef PACK_STRUCT_USE_INCLUDES
+#  include "arch/bpstruct.h"
+#endif
 PACK_STRUCT_BEGIN
 /** the ARP message */
 struct etharp_hdr {
@@ -78,12 +90,19 @@ struct etharp_hdr {
   PACK_STRUCT_FIELD(struct ip_addr2 dipaddr);
 } PACK_STRUCT_STRUCT;
 PACK_STRUCT_END
+#ifdef PACK_STRUCT_USE_INCLUDES
+#  include "arch/epstruct.h"
+#endif
 
+#ifdef PACK_STRUCT_USE_INCLUDES
+#  include "arch/bpstruct.h"
+#endif
 PACK_STRUCT_BEGIN
 struct ethip_hdr {
   PACK_STRUCT_FIELD(struct eth_hdr eth);
   PACK_STRUCT_FIELD(struct ip_hdr ip);
-};
+} PACK_STRUCT_STRUCT;
+PACK_STRUCT_END
 #ifdef PACK_STRUCT_USE_INCLUDES
 #  include "arch/epstruct.h"
 #endif

src/netif/etharp.c

@@ -752,8 +752,15 @@ err_t etharp_query(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
       p = pbuf_take(q);
       /* packet could be taken over? */
       if (p != NULL) {
-        /* queue packet */
-        pbuf_queue(arp_table[i].p, p);
+        /* queue packet ... */
+        if (arp_table[i].p == NULL) {
+        	/* ... in the empty queue */
+        	pbuf_ref(p);
+        	arp_table[i].p = p;
+        } else {
+        	/* ... at tail of non-empty queue */
+          pbuf_queue(arp_table[i].p, p);
+        }
         LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: queued packet %p on ARP entry %d\n", (void *)q, i));
         result = ERR_OK;
       } else {

src/netif/ethernetif.c

@@ -273,7 +273,7 @@ arp_timer(void *arg)
  *
  */
 
-void
+err_t
 ethernetif_init(struct netif *netif)
 {
   struct ethernetif *ethernetif;
@@ -299,5 +299,7 @@ ethernetif_init(struct netif *netif)
   etharp_init();
 
   sys_timeout(ARP_TMR_INTERVAL, arp_timer, NULL);
+
+  return ERR_OK;
 }