Diff: PPP-Blinky/ppp-blinky.cpp

Revision:

163:d1b4328e9f08

Parent:

162:594729c0e5c1

Child:

164:c3de3d212c4b

--- a/PPP-Blinky/ppp-blinky.cpp	Sat Sep 02 18:14:26 2017 +0000
+++ b/PPP-Blinky/ppp-blinky.cpp	Sun Sep 03 01:29:01 2017 +0000
@@ -165,6 +165,8 @@
     union {
         tcpHeaderType * tcp; // pointer to tcp header struct
         char * tcpStart; // char pointer to tcp header struct (need a char pointer for byte offset calculations)
+        udpHeaderType * udp; // pointer to udp header struct
+        char * udpStart; // char pointer to udp header struct (need a char pointer for byte offset calculations)
     };
     int online; // we hunt for a PPP connection if this is zero
     int hostIP; // ip address of host
@@ -543,31 +545,38 @@
 /// If the packet starts with the string "echo " or "test" we echo back a special packet
 void UDPpacket()
 {
-    char * ipHeader     = ppp.pkt.buf+4; // udp packet start
-    char * ipSizeBuf    = ipHeader+2; // size of IP packet
-    int headerSizeIP    = 4*(ipHeader[0]&0xf); // size of IP header
-    char * udpHeader    = ipHeader + headerSizeIP; // udp info start
-    char * udpLen       = udpHeader+4; // udp data length
-    char * udpCheckSum  = udpHeader+6; // udp checksum
-    char * udpData = udpHeader+8; // start of UDP data
-    int udpLength = ((udpLen[0]<<8) | udpLen[1]); // size of udp packet
-    int udpDataSize = udpLength - 8; // size of udp data
+    struct {
+        unsigned int all; // length of entire ip packet
+        unsigned int header; // length of ip header
+    } ipLength;
+
+    struct {
+        unsigned int all; // lenght of entire udp packet
+        unsigned int data; // length of udp data segment
+    } udpLength;
+
+    ipLength.header = 4 * ppp.ip->headerLength; // length of ip header
+    ppp.udpStart = ppp.ipStart + ipLength.header; // calculate start of udp header
+    udpLength.all = __REV16( ppp.udp->lengthR ); //((udpLen[0]<<8) | udpLen[1]); // size of udp packet
+    udpLength.data = udpLength.all - 8; // size of udp data
 
 #ifdef SERIAL_PORT_MONITOR_YES
-    char * srcIP        = ipHeader+12; // IP source
-    char * dstIP        = ipHeader+16; // IP destination
-    char * udpSrcPort   = udpHeader+0; // source port
-    char * udpDstPort   = udpHeader+2; // destination port
-    int udpSrc = (udpSrcPort[0]<<8)|udpSrcPort[1]; // integer of UDP source port
-    int udpDst = (udpDstPort[0]<<8)|udpDstPort[1]; // integer of UDP dest port
-    if(v0) debugPrintf("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],udpSrc);
-    if(v0) debugPrintf("%d.%d.%d.%d:%d ",     dstIP[0],dstIP[1],dstIP[2],dstIP[3],udpDst);
-    if(v0) debugPrintf("Len %03d", udpLength);
+    char * srcIP        = (char *)&ppp.ip->srcAdrR; //ipHeader+12; // IP source
+    char * dstIP        = (char *)&ppp.ip->dstAdrR; //ipHeader+16; // IP destination
+
+    unsigned int udpSrcPort = __REV16( ppp.udp->srcPortR ); //(udpSrcPort[0]<<8)|udpSrcPort[1]; // integer of UDP source port
+    unsigned int udpDstPort = __REV16( ppp.udp->dstPortR ); //(udpDstPort[0]<<8)|udpDstPort[1]; // integer of UDP dest port
+
+    if(v0) {
+        debugPrintf("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],udpSrcPort);
+        debugPrintf("%d.%d.%d.%d:%d ",     dstIP[0],dstIP[1],dstIP[2],dstIP[3],udpDstPort);
+        debugPrintf("Len %03d", udpLength);
+    }
     if (v1) {
-        int printSize = udpLength-8;
+        int printSize = udpLength.data;
         if (printSize > 20) printSize = 20; // print only first 20 characters
         for (int i=0; i<printSize; i++) {
-            char ch = udpData[i];
+            char ch = ppp.udp->data[i];
             if (ch>31 && ch<127) {
                 debugPrintf("%c", ch);
             } else {
@@ -577,33 +586,33 @@
     }
     if (v0) debugPrintf("\n");
 #endif
-    int echoFound = !strncmp(udpData,"echo ",5); // true if UDP message starts with "echo "
-    int testFound = !strncmp(udpData,"test" ,4); // true if UDP message starts with "test"
+    int echoFound = !strncmp(ppp.udp->data,"echo ",5); // true if UDP message starts with "echo "
+    int testFound = !strncmp(ppp.udp->data,"test" ,4); // true if UDP message starts with "test"
     if ( (echoFound) || (testFound)) { // if the UDP message starts with "echo " or "test" we answer back
         swapIpAddresses(); // swap IP source and destination
         swapIpPorts(); // swap IP source and destination ports
         if (echoFound) {
-            memcpy(udpData,"Got{",4); // in the UDP data modify "echo" to "Got:"
+            memcpy(ppp.udp->data,"Got{",4); // in the UDP data modify "echo" to "Got:"
             char endString[] = "} UDP Server: PPP-Blinky\n"; // an appendix
-            memcpy(udpData+udpLength-8,endString,sizeof(endString)-1); // add endstring size to the UDP message
-            udpDataSize = udpDataSize + sizeof(endString)-1; // update udp data size with the size of the appendix
+            memcpy(ppp.udp->data+udpLength.data,endString,sizeof(endString)-1); // add endstring size to the UDP message
+            udpLength.all = udpLength.data + sizeof(endString)-1; // update udp data size with the size of the appendix
         }
         if (testFound) {
             char udpResponse[50];
             int n = 0;
             n = n+sprintf(udpResponse+n,"Response count %d\n",ppp.responseCounter++);
-            memcpy(udpData,udpResponse,n); // copy response to the UDP data area
-            udpDataSize = n; // new udp data size
+            memcpy(ppp.udp->data,udpResponse,n); // copy response to the UDP data area
+            udpLength.data = n; // update udp data size
         }
-        udpLength = udpDataSize+8; // update udp packet length
-        int ipSize = headerSizeIP + udpLength; // update ip packet length
-        ppp.pkt.len = ipSize+2+4; // update ppp packet length
-        udpLen[0]    = udpLength>>8;
-        udpLen[1]    = udpLength; // update UDP length
-        ipSizeBuf[0] = ipSize>>8;
-        ipSizeBuf[1] = ipSize; // update IP length
-        IpHeaderCheckSum();  // update IP header checksum
-        memset(udpCheckSum,0,2); // we don't yet recompute the checksum (it's optional), so have to zero it
+        // we may have changed data length, update all the lengths
+        udpLength.all    = udpLength.data+8; // update local udp packet length
+        ipLength.all     = ipLength.header + udpLength.all; // update IP Length
+        ppp.ip->lengthR  = __REV16(ipLength.all); // update IP length in buffer
+        ppp.udp->lengthR = __REV16(udpLength.all); // update UDP length in buffer
+        ppp.pkt.len      = ipLength.all+2+4; // update ppp packet length
+        
+        IpHeaderCheckSum();  // refresh IP header checksum
+        ppp.udp->checkSumR = 0; // we don't yet recompute the UDP checksum (it's optional), so have to zero it
         sendPppFrame(); // send the UDP message back
     }
 }
@@ -688,8 +697,8 @@
     n=n+sprintf(pbuf+n, "%05d ",IPv4Id); // IPv4Id is a good way to correlate our dumps with net monitor or wireshark traces
 #define DUMP_FULL_IP_ADDRESS_YES
 #ifdef DUMP_FULL_IP_ADDRESS_YES
-    char * srcAdr = (char *)&ppp.ip->srcAdrR; 
-    char * dstAdr = (char *)&ppp.ip->dstAdrR; 
+    char * srcAdr = (char *)&ppp.ip->srcAdrR;
+    char * dstAdr = (char *)&ppp.ip->dstAdrR;
     n=n+sprintf(pbuf+n, " %d.%d.%d.%d %d.%d.%d.%d ",srcAdr[0],srcAdr[1],srcAdr[2],srcAdr[3], dstAdr[0],dstAdr[1],dstAdr[2],dstAdr[3]); // full ip addresses
 #endif
     putsWhileCheckingInput( pbuf );
@@ -886,7 +895,7 @@
         dataStart[1]=0; // we don't have mask bytes on
     } else {
         if (v1) putsWhileCheckingInput("TCP data received\n"); // all other tcp push packets
-    }        
+    }
     return n; // total byte size of our response
 }