Update the NMEA client support program

Enable the NMEA client program to forward data from the RTK NMEA TCP
server to the Vespucci NMEA server.

Use this on a local WiFi network.  Both the RTK and the Android phone
need to connect to the local WiFi network.  This NMEA client program
eliminates the RTK NMEA client code and validates the Android connection
to the Vespucci NMEA server.  Once the Android connection is working, it
is easy to enable the RTK NMEA client by enabling the Mobile Hot Spot on
the phone and switching the WiFi SSID and password in the RTK.

Author: LeeLeahy2

Firmware/Tools/NMEA_Client.c

@@ -20,62 +20,120 @@ main (
     )
 {
     int bytesRead;
-    int nmeaSocket;
-    struct sockaddr_in serverIpAddress;
+    int bytesWritten;
+    int displayHelp;
+    struct sockaddr_in rtkServerIpAddress;
+    int rtkSocket;
+    int status;
+    struct sockaddr_in vespucciServerIpAddress;
+    int vespucciSocket;
 
+    do {
+        displayHelp = 1;
+        status = 0;
+        if ((argc < 2) || (argc > 3))
+        {
+            status = -1;
+            break;
+        }
 
-    // Display the help text
-    if (argc != 2)
-    {
-        printf ("%s   serverIpAddress\n", argv[0]);
-        return -1;
-    }
-
-    // Initialize the server address
-    memset (&serverIpAddress, '0', sizeof(serverIpAddress));
-    serverIpAddress.sin_family = AF_INET;
-    serverIpAddress.sin_addr.s_addr = htonl(INADDR_ANY);
-    serverIpAddress.sin_port = htons(1958);
-    if (inet_pton (AF_INET, argv[1], &serverIpAddress.sin_addr) <= 0)
-    {
-        perror ("ERROR - Invalid IPv4 address!\n");
-        return -2;
-    }
-
-    //Create the socket
-    nmeaSocket = socket(AF_INET, SOCK_STREAM, 0);
-    if (nmeaSocket < 0)
-    {
-        perror ("ERROR - Unable to create the client socket!\n");
-        return -3;
-    }
-
-    if (connect (nmeaSocket, (struct sockaddr *)&serverIpAddress, sizeof(serverIpAddress)) < 0)
-    {
-       perror("Error : Failed to connect to NMEA server!\n");
-       return -4;
-    }
-
-    // Read the NMEA data from the client
-    while ((bytesRead = read (nmeaSocket, rxBuffer, sizeof(rxBuffer)-1)) > 0)
-    {
-        // Zero terminate the NMEA string
-        rxBuffer[bytesRead] = 0;
-
-        // Output the NMEA buffer
-        if (fputs ((char *)rxBuffer, stdout) == EOF)
+        // Initialize the RTK server address
+        memset (&rtkServerIpAddress, '0', sizeof(rtkServerIpAddress));
+        rtkServerIpAddress.sin_family = AF_INET;
+        rtkServerIpAddress.sin_addr.s_addr = htonl(INADDR_ANY);
+        rtkServerIpAddress.sin_port = htons(1958);
+        if (inet_pton (AF_INET, argv[1], &rtkServerIpAddress.sin_addr) <= 0)
+        {
+            perror ("ERROR - Invalid RTK server IPv4 address!\n");
+            status = -2;
+            break;
+        }
+
+        if (argc == 3)
         {
-            perror ("ERROR - Failed to write to stdout!\n");
-            return -5;
+            // Initialize the Vespucci server address
+            memset (&vespucciServerIpAddress, '0', sizeof(vespucciServerIpAddress));
+            vespucciServerIpAddress.sin_family = AF_INET;
+            vespucciServerIpAddress.sin_addr.s_addr = htonl(INADDR_ANY);
+            vespucciServerIpAddress.sin_port = htons(1958);
+            if (inet_pton (AF_INET, argv[2], &vespucciServerIpAddress.sin_addr) <= 0)
+            {
+                perror ("ERROR - Invalid Vespucci IPv4 address!\n");
+                status = -3;
+                break;
+            }
+            displayHelp = 0;
+
+            //Create the vespucci socket
+            vespucciSocket = socket(AF_INET, SOCK_STREAM, 0);
+            if (vespucciSocket < 0)
+            {
+                perror ("ERROR - Unable to create the Vespucci client socket!\n");
+                status = -4;
+                break;
+            }
+
+            if (connect (vespucciSocket, (struct sockaddr *)&vespucciServerIpAddress, sizeof(vespucciServerIpAddress)) < 0)
+            {
+               perror("Error : Failed to connect to Vespucci NMEA server!\n");
+               status = -5;
+               break;
+            }
+        }
+        displayHelp = 0;
+
+        //Create the RTK socket
+        rtkSocket = socket(AF_INET, SOCK_STREAM, 0);
+        if (rtkSocket < 0)
+        {
+            perror ("ERROR - Unable to create the RTK client socket!\n");
+            status = -6;
+            break;
         }
-    }
 
-    if (bytesRead < 0)
-    {
-        perror ("ERROR - Failed reading from NMEA server!\n");
-        return -6;
-    }
+        if (connect (rtkSocket, (struct sockaddr *)&rtkServerIpAddress, sizeof(rtkServerIpAddress)) < 0)
+        {
+           perror("Error : Failed to connect to RTK NMEA server!\n");
+           status = -7;
+           break;
+        }
+
+        // Read the NMEA data from the RTK server
+        while ((bytesRead = read (rtkSocket, rxBuffer, sizeof(rxBuffer)-1)) > 0)
+        {
+            // Zero terminate the NMEA string
+            rxBuffer[bytesRead] = 0;
+
+            // Output the NMEA buffer
+            if (fputs ((char *)rxBuffer, stdout) == EOF)
+            {
+                perror ("ERROR - Failed to write to stdout!\n");
+                status = -8;
+                break;
+            }
+
+            // Forward the NMEA data to the Vespucci server
+            if (argc == 3)
+            {
+                if ((bytesWritten = write (vespucciSocket, rxBuffer, bytesRead)) != bytesRead)
+                {
+                    perror ("ERROR - Failed to write to Vespucci socket");
+                    status = -9;
+                    break;
+                }
+            }
+        }
+
+        if (bytesRead <= 0)
+        {
+            perror ("ERROR - Failed reading from NMEA server!\n");
+            status = -10;
+        }
+    } while (0);
+
+    // Display the help text
+    if (displayHelp)
+        printf ("%s   RtkServerIpAddress   [VespucciServerIpAddress]\n", argv[0]);
 
-    // Successful execution
-    return 0;
+    return status;
 }