Diff: main.cpp

Revision:

36:2a9b457f8276

Parent:

35:e7068df4d971

Child:

37:2e6689f8b181

--- a/main.cpp	Thu Jan 05 08:16:50 2017 +0000
+++ b/main.cpp	Thu Jan 05 10:32:12 2017 +0000
@@ -53,6 +53,7 @@
     unsigned int seq;
     int crc;
     int ledState;
+    int oldFlags;
     struct {
         char * buf;
         volatile int head;
@@ -83,6 +84,7 @@
     ppp.sync=0;
     ppp.seq=1000;
     ppp.ledState=0;
+    ppp.oldFlags=0;
 }
 
 void crcReset()
@@ -513,20 +515,21 @@
     // A sparse TCP flag interpreter that implements basic TCP connections from a single source
 
     int dataLen = 0; // most of our responses will have zero TCP data, only a header
-    int teardown = 0; // see if we must tear down the link
+    int flagsOut = TCP_FLAG_ACK; // the default case is an ack
+    int fastResponse = 0; // normally we wait 200ms before sending but this can make it faster
 
     if ( ((flagsTCP & ~TCP_FLAG_ACK) == 0) && ((flagsTCP & TCP_FLAG_ACK) != 0) ) {
-       if (incomingLen == 0) return; // no new data
+        if (incomingLen == 0) return; // no new data
     } else if ( (flagsTCP & TCP_FLAG_FIN) != 0 ) { // got FIN
-        flagbitstcp[1] = TCP_FLAG_ACK; // do an ack
-        teardown=1;
+        if ((ppp.oldFlags & TCP_FLAG_FIN) !=0) return;
+        seq++; // increase sequence by 1 for FIN and SYNC
     } else if ( (flagsTCP & TCP_FLAG_SYN) != 0 ) { // got SYN
-        flagbitstcp[1] |= TCP_FLAG_ACK; // do a syn-ack
-        seq++;
+        flagsOut = TCP_FLAG_SYN | TCP_FLAG_ACK; // do a syn-ack
+        seq++; // increase sequency by for FIN and SYN
     } else if ( (flagsTCP & TCP_FLAG_PSH) != 0 ) { // they are pushing data
+        fastResponse = 1; // we can response fast to a push
         // It's a push - let's check the data for an HTTP home page GET request
         if ( strncmp(dataStart, "GET / HTTP/1.1", 14) == 0) {
-            flagbitstcp[1] = TCP_FLAG_ACK; // | TCP_FLAG_FIN; // close connection after delivering page
             dataLen = 15*32; // this block has to hold the web page below, but keep it under 1k
             memset(dataStart,'x', dataLen ); // initialize the block
             int n=1; // number of bytes we have printed so far
@@ -545,7 +548,6 @@
                 debug(("HTTP GET dataLen %d*32=%d Header %d Content-Length %d Total %d Margin %d\n",dataLen/32,dataLen,nHeader,contentLength,n,dataLen-n));
             }
         } else if ( strncmp(dataStart, "GET /", 4) == 0) { // all other files get 404 not found
-            flagbitstcp[1] = TCP_FLAG_ACK;// | TCP_FLAG_FIN; // close connection after delivering page
             dataLen = 5*32; // this block has to hold the web page below, but keep it under 1k
             memset(dataStart,'x', dataLen ); // initialize the block
             int n=0;
@@ -561,36 +563,20 @@
                 debug(("HTTP GET dataLen %d*32=%d Header %d Content-Length %d Total %d Margin %d\n",dataLen/32,dataLen,nHeader,contentLength,n,dataLen-n));
             }
         } else {
-            flagbitstcp[1] = TCP_FLAG_ACK; // we have nothing to say, just ack
             dataLen=0;
         }
+    } else {
+        dataLen=0;
     }
 
     // All the flag checking is now donw
 
+    ppp.oldFlags = flagsTCP; // remember the flags for the next round
+
     // Now we have to recalculate all the header sizes
 
     ack = seq + incomingLen; // acknowledge the number of bytes they sent by adding it to seq
     seq = ppp.seq;
-    
-teardownEntry:
-
-    int newPacketSize = headerSizeIP + headerSizeTCP + dataLen;
-    pktLen[0] = (newPacketSize>>8);
-    pktLen[1]=newPacketSize; // ip total packet size
-    ppp.pkt.len = newPacketSize+6; // ppp packet length
-    tcpSize = headerSizeTCP + dataLen; // tcp packet size
-
-    // redo all the header stuff
-
-    acktcp[0]=ack>>24;
-    acktcp[1]=ack>>16;
-    acktcp[2]=ack>>8;
-    acktcp[3]=ack>>0; // save ack
-    seqtcp[0]=seq>>24;
-    seqtcp[1]=seq>>16;
-    seqtcp[2]=seq>>8;
-    seqtcp[3]=seq>>0; // save seq
 
     char src[4];
     char dst[4];
@@ -605,6 +591,27 @@
     memcpy(srctcp, pdst,2);
     memcpy(dsttcp, psrc,2); // swap ip port source/dest
 
+
+    int newPacketSize = headerSizeIP + headerSizeTCP + dataLen;
+    pktLen[0] = (newPacketSize>>8);
+    pktLen[1]=newPacketSize; // ip total packet size
+    ppp.pkt.len = newPacketSize+6; // ppp packet length
+    tcpSize = headerSizeTCP + dataLen; // tcp packet size
+
+    flagbitstcp[1] = flagsOut; // set up the new flags
+
+    acktcp[0]=ack>>24;
+    acktcp[1]=ack>>16;
+    acktcp[2]=ack>>8;
+    acktcp[3]=ack>>0; // save ack
+    seqtcp[0]=seq>>24;
+    seqtcp[1]=seq>>16;
+    seqtcp[2]=seq>>8;
+    seqtcp[3]=seq>>0; // save seq
+
+
+    // redo all the header stuff
+
     headercheck[0]=0;
     headercheck[1]=0;
     headerCheckSum(); // redo the ip header checksum
@@ -624,14 +631,13 @@
     checksumtcp[0]=sum>>8;
     checksumtcp[1]=sum;
     memcpy( s-12, temp, 12); // overwrite the pseudoheader
+    if (fastResponse==1) {
+        fastResponse=0; // reset and skip 200 ms wait
+    } else {
+        wait(0.2); // wait 200 ms before sending packet
+    }
     sendFrame(); // return the TCP packet
     ppp.seq = ppp.seq + dataLen; // increase OUR sequence by outgoing data length - for the next round
-    if (teardown) {
-        teardown=0; // clear the teardown flag
-        flagbitstcp[1] = TCP_FLAG_FIN; // we want to end the link
-        dataLen=0; // no data needed
-        goto teardownEntry;
-    }
 }
 
 void dumpDataTCP()