Comment much of PacketSensor.cc while looking for bugs.

Add a lot of additional debugging output.

Fix incorrect TCP payload size calculation - assumed Ethernet,
ignored IP and TCP option headers.

Replace weird nonstandart IpHeader structure with 'struct ip' from
netinet/ip.h .

pelab/magent/KernelTcp.cc

@@ -17,7 +17,7 @@ namespace
   int getLinkLayer(struct pcap_pkthdr const * pcapInfo,
                    unsigned char const * packet);
   void handleTcp(struct pcap_pkthdr const * pcapInfo,
-                 IpHeader const * ipPacket,
+                 struct ip const * ipPacket,
                  struct tcphdr const * tcpPacket);
   void handleKernel(Connection * conn, struct tcp_info * kernel);
 }
@@ -407,13 +407,13 @@ namespace
       logWrite(ERROR, "Unknown link layer type: %d", packetType);
       return;
     }
-    IpHeader const * ipPacket;
+    struct ip const * ipPacket;
     struct tcphdr const * tcpPacket;
     size_t bytesRemaining = pcapInfo->caplen - sizeof(struct ether_header);
 
-    ipPacket = reinterpret_cast<IpHeader const *>
+    ipPacket = reinterpret_cast<struct ip const *>
       (packet + sizeof(struct ether_header));
-    if (bytesRemaining < sizeof(IpHeader))
+    if (bytesRemaining < sizeof(struct ip))
     {
       logWrite(ERROR, "A captured packet was too short to contain an "
                "IP header");
@@ -421,8 +421,8 @@ namespace
     }
     // ipHeaderLength and version are in a one byte field so
     // endian-ness doesn't matter.
-    int ipHeaderLength = IP_HL(ipPacket);
-    int version = IP_V(ipPacket);
+    int ipHeaderLength = ipPacket->ip_hl;
+    int version = ipPacket->ip_v;
     if (version != 4)
     {
       logWrite(ERROR, "A non IPv4 packet was captured");
@@ -472,7 +472,7 @@ namespace
   }
 
   void handleTcp(struct pcap_pkthdr const * pcapInfo,
-                 IpHeader const * ipPacket,
+                 struct ip const * ipPacket,
                  struct tcphdr const * tcpPacket)
   {
     logWrite(PCAP, "Captured a TCP packet");

pelab/magent/PacketSensor.cc

@@ -32,9 +32,18 @@ Time const & PacketSensor::getAckedSendTime(void) const
 
 void PacketSensor::localSend(PacketInfo * packet)
 {
+  logWrite(SENSOR,
+           "PacketSensor::localSend() for sequence number %i",
+            ntohl(packet->tcp->seq));
   unsigned int startSequence = ntohl(packet->tcp->seq);
   if (globalSequence.inSequenceBlock(startSequence))
   {
+    logWrite(SENSOR,
+             "PacketSensor::localSend() within globalSequence");
+    /*
+     * This packet should be in our list of sent packets - ie. it's a
+     * retransmit.
+     */
     list<SentPacket>::iterator pos = unacked.begin();
     list<SentPacket>::iterator limit = unacked.end();
     bool done = false;
@@ -46,23 +55,46 @@ void PacketSensor::localSend(PacketInfo * packet)
         done = true;
       }
     }
+
+    if (!done) {
+      logWrite(ERROR, "localSend() unable to find packet record to update.");
+    }
   }
   else
   {
+    /*
+     * Not in the current window of unacked packets - create a new
+     * SentPacket record for it
+     */
     SentPacket record;
     record.seqStart = startSequence;
-    unsigned int sequenceLength = packet->packetLength -
-      sizeof(struct ether_header) - IP_HL(packet->ip)*4 -
-      sizeof(struct tcphdr);
+
+    /*
+     * Caclulate the packet payload size - we have to make sure to take into
+     * account IP and TCP option headers
+     */
+    unsigned int sequenceLength =
+        // Total length of the IP part of the packet
+        (ntohs(packet->ip->ip_len))
+        // Total length of all IP headers (including options)
+         - (packet->ip->ip_hl*4)
+        // Total length of all TCP headers (including options)
+         - (packet->tcp->doff*4);
     record.seqEnd = record.seqStart + sequenceLength;
     record.totalLength = packet->packetLength;
     record.timestamp = packet->packetTime;
+    logWrite(SENSOR,
+             "PacketSensor::localSend() new record: ss=%i,sl=%i,se=%i,tl=%i",
+             record.seqStart);
     globalSequence.seqEnd = record.seqEnd;
     if (unacked.empty())
     {
       globalSequence.seqStart = record.seqStart;
       globalSequence.seqEnd = record.seqEnd;
     }
+    logWrite(SENSOR,
+             "PacketSensor::localSend(): global start = %i, global end = %i",
+             globalSequence.seqStart, globalSequence.seqEnd);
     unacked.push_back(record);
   }
 
@@ -80,6 +112,10 @@ void PacketSensor::localAck(PacketInfo * packet)
   while (pos != limit && !found)
   {
     found = pos->inSequenceBlock(ntohl(packet->tcp->ack_seq));
+    /*
+     * XXX: Assumes that SACK is not in use - assumes that this ACK is for all
+     * sequence numbers up to the one it's ACKing
+     */
     ackedSize += pos->totalLength;
     if (found)
     {
@@ -113,7 +149,7 @@ void PacketSensor::localAck(PacketInfo * packet)
 bool PacketSensor::SentPacket::inSequenceBlock(unsigned int sequence)
 {
   logWrite(SENSOR,
-           "PacketSensor inSequencBlock(): Is %u between %u and %u?",
+           "PacketSensor::inSequenceBlock(): Is %u between %u and %u?",
            sequence, seqStart, seqEnd);
   bool result = false;
   if (seqStart < seqEnd)
@@ -122,6 +158,9 @@ bool PacketSensor::SentPacket::inSequenceBlock(unsigned int sequence)
   }
   else if (seqStart > seqEnd)
   {
+    /*
+     * This handles the sequence number wrapping around
+     */
     result = sequence >= seqStart || sequence < seqEnd;
   }
   if (result)

pelab/magent/lib.h

@@ -165,25 +165,6 @@ struct WriteResult
   Time nextWrite;
 };
 
-struct IpHeader
-{
-  unsigned char ip_vhl;         /* header length, version */
-#define IP_V(ip)        (((ip)->ip_vhl & 0xf0) >> 4)
-#define IP_HL(ip)       ((ip)->ip_vhl & 0x0f)
-  unsigned char ip_tos;         /* type of service */
-  unsigned short ip_len;         /* total length */
-  unsigned short ip_id;          /* identification */
-  unsigned short ip_off;         /* fragment offset field */
-#define IP_DF 0x4000                    /* dont fragment flag */
-#define IP_MF 0x2000                    /* more fragments flag */
-#define IP_OFFMASK 0x1fff               /* mask for fragmenting bits */
-  unsigned char ip_ttl;         /* time to live */
-  unsigned char ip_p;           /* protocol */
-  unsigned short ip_sum;         /* checksum */
-  struct in_addr ip_src;
-  struct in_addr ip_dst;  /* source and dest address */
-};
-
 struct PacketInfo
 {
   //                        packetTime+packetLength+kernel+elab
@@ -195,7 +176,7 @@ struct PacketInfo
   Time packetTime;
   int packetLength;
   struct tcp_info const * kernel;
-  IpHeader const * ip;
+  struct ip const * ip;
   struct tcphdr const * tcp;
   Order elab;
   bool bufferFull;