Changes between Version 6 and Version 7 of Docs/Prog/Manual/DeviceSupport/Network

Timestamp:

01/13/10 16:20:58 (14 years ago)

Author:

Don Wilson

Comment:

--

Docs/Prog/Manual/DeviceSupport/Network

@@ -104 +104 @@
 
 {{{
-//============================================================================
-// Name        : tcpip_server.cpp
-// Author      : Don Wilson
-// Version     :
-// Copyright   : Cardinal Scale Mfg
-// Description : TCP/IP Server Demo
-//============================================================================
+// TCP/IP Server Demo
 
 #include <stdio.h>
@@ -136 +130 @@
 using namespace std;
 
+const int BUFSIZE = 30;
+
+// To allow for multiple-byte requests from clients we have to keep a separate receive buffer for each client
+struct client_info
+{
+   int socket;
+   char buf[BUFSIZE];
+   int pos;
+};
+
 // Dynamic list to keep track of connected clients
-vector<int> client_list;
+vector<client_info> client_list;
 
 int server_s;
@@ -147 +151 @@
 int ServerProcess(void)
 {
-        int i;
-        int client_s;
-        struct sockaddr_in addr;
-        socklen_t socklen = sizeof(addr);
-
-        // Check for new client connections
-        client_s = accept(server_s, (sockaddr*)&addr, &socklen);
-        if(client_s >= 0)
-        {
-                char szIP[INET_ADDRSTRLEN];
-
-                inet_ntop(AF_INET, &addr.sin_addr, szIP, INET_ADDRSTRLEN);
-
-                printf("TCP/IP server connection from %s socket %d\r\n", szIP, client_s);
-
-            /* nonblocking socket */
-            if (fcntl(client_s, F_SETFL, O_NONBLOCK) == -1)
-                {
-                printf("fcntl: unable to set new socket to non-block\r\n");
-                close(client_s);
-            }
-            else
-            {
-                client_list.push_back(client_s);
-            }
-        }
-
-        if(client_list.size() > 0)
-        {
-                fd_set rfds;
-                FD_ZERO(&rfds);
-                int nMaxfd = 0;
-                for(i = 0; i < (int)client_list.size(); i++)
-                {
-                        FD_SET(client_list[i], &rfds);
-                        if(client_list[i] > nMaxfd)
-                                nMaxfd = client_list[i];
-                }
-
-                struct timeval tv;
-                tv.tv_sec = 0;
-                tv.tv_usec = 0;
-
-                int retval = select(nMaxfd + 1, &rfds, NULL, NULL, &tv);
-                if(retval == -1)
-                        printf("select return -1\r\n");
-                else if(retval > 0)
-                {
-                        printf("select returned %d\r\n", retval);
-
-                        int rcvlen;
-                        char data[20], sendbuf[50];
-                        int z;
-                        int remove = -1;
-
-                        // Process all connected clients
-                        for(i = 0; i < (int)client_list.size(); i++)
-                        {
-                                if(FD_ISSET(client_list[i], &rfds))
-                                {
-                                        rcvlen = recv(client_list[i], data, sizeof(data), 0);
-                                        for(z = 0; z < rcvlen; z++)
-                                        {
-                                                if(data[z] == 0x05)  // ENQ = CTRL-E received
-                                                {
-                                                        // Send response to client
-                                                        time_t rawtime;
-                                                        struct tm *timeinfo;
-                                                        time(&rawtime);
-                                                        timeinfo = localtime(&rawtime);
-
-                                                        sprintf(sendbuf, "Server time is: %02d:%02d:%02d ",
-                                                                        timeinfo->tm_hour, timeinfo->tm_min, timeinfo->tm_sec);
-
-                                                        send(client_list[i], sendbuf, strlen(sendbuf), 0);
-                                                }
-                                        }
-                                        if(rcvlen <= 0)
-                                        {
-                                                printf("recv Error %d\r\n", rcvlen);
-                                                remove = i;
-                                        }
-                                }
-                        }
-                        if(remove >= 0)
-                        {
-                                printf("Removing %d client socket %d\r\n", remove, client_list[remove]);
-                                client_list.erase(client_list.begin() + remove);
-                        }
-                }
-        }
-        return 0;
+   int i;
+   int client_s;
+   struct sockaddr_in addr;
+   socklen_t socklen = sizeof(addr);
+
+   // Check for new client connections
+   client_s = accept(server_s, (sockaddr*)&addr, &socklen);
+   if(client_s >= 0)
+   {
+      char szIP[INET_ADDRSTRLEN];
+      inet_ntop(AF_INET, &addr.sin_addr, szIP, INET_ADDRSTRLEN);
+
+      printf("TCP/IP server connection from IP %s socket %d\r\n", szIP, client_s);
+
+      /* nonblocking socket */
+      if(fcntl(client_s, F_SETFL, O_NONBLOCK) == -1)
+      {
+         printf("fcntl: unable to set new socket to non-block\r\n");
+         close(client_s);
+      }
+      else
+      {
+         // Add client information to list of connected clients
+         client_info info;
+         info.socket = client_s;
+         info.pos = 0;
+         client_list.push_back(info);
+      }
+   }
+
+   // Service any connected clients
+   if(client_list.size() > 0)
+   {
+      struct timeval tv;
+      tv.tv_sec = 0;
+      tv.tv_usec = 0;
+
+      // Load up structure for "select" statement to check for receive data from all connected clients
+      fd_set rfds;
+      FD_ZERO(&rfds);
+      int nMaxfd = 0;
+      for(i = 0; i < (int)client_list.size(); i++)
+      {
+         FD_SET(client_list[i].socket, &rfds);
+         if(client_list[i].socket > nMaxfd)
+            nMaxfd = client_list[i].socket;
+      }
+
+      int retval = select(nMaxfd + 1, &rfds, NULL, NULL, &tv);
+      if(retval == -1)
+      {
+         printf("select return -1\r\n");
+      }
+      else if(retval > 0)
+      {
+         int rcvlen;
+         char data[20], sendbuf[50];
+         int z;
+         int remove = -1;
+
+         // Loop through array of all connected clients
+         for(i = 0; i < (int)client_list.size(); i++)
+         {
+            // Select statement will have loaded rfds to identify which clients have data available to read from
+            if(FD_ISSET(client_list[i].socket, &rfds))
+            {
+               rcvlen = recv(client_list[i].socket, data, sizeof(data), 0);
+               // Loop through bytes received from this client
+               for(z = 0; z < rcvlen; z++)
+               {
+                  // If ENTER we have completed message - otherwise add character to the client read buffer
+                  if(data[z] == '\r')
+                  {
+                     // Must terminate the string
+                     client_list[i].buf[client_list[i].pos] = '\0';
+                     printf("Socket %d message [%s]\r\n", client_list[i].socket, client_list[i].buf);
+
+                     // In this sample we check for "TIME<CR>" received and respond with the server time
+                     if(!strcmp(client_list[i].buf, "TIME"))
+                     {
+                        // Get current time
+                        time_t rawtime;
+                        struct tm *timeinfo;
+                        time(&rawtime);
+                        timeinfo = localtime(&rawtime);
+
+                        // Format time into string
+                        sprintf(sendbuf, "Server time is: %02d:%02d:%02d ",
+                           timeinfo->tm_hour, timeinfo->tm_min, timeinfo->tm_sec);
+
+                        // Send to client
+                        send(client_list[i].socket, sendbuf, strlen(sendbuf), 0);
+                     }
+
+                     // Reset the buffer position for the next request
+                     client_list[i].pos = 0;
+                  }
+                  else
+                  {
+                     // Add character to buffer
+                     client_list[i].buf[client_list[i].pos++] = data[z];
+
+                     // In case of overflow reset position to prevent overwriting memory and crashing
+                     if(client_list[i].pos >= BUFSIZE)
+                        client_list[i].pos = 0;
+                  }
+               }
+               if(rcvlen <= 0)
+               {
+                  // If the receive length is zero or negative indicates an error - we lost the connection
+                  // Set variable remove to indicate this client should be removed
+                  printf("recv Error %d\r\n", rcvlen);
+                  remove = i;
+               }
+            }
+         }
+         if(remove >= 0)
+         {
+            // If a client disconnected remove it from the list
+            printf("Removing %d client socket %d\r\n", remove, client_list[remove].socket);
+            client_list.erase(client_list.begin() + remove);
+         }
+      }
+   }
+   return 0;
 }
 
 int main()
 {
-
-        server_s = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
-        if(server_s == -1)
-        {
-                printf("unable to create socket\r\n");
-                return -1;
-        }
-
-    /* server socket is nonblocking */
-    if (fcntl(server_s, F_SETFL, O_NONBLOCK) == -1)
-    {
-            printf("fcntl: unable to set server socket to nonblocking");
-            return -1;
-    }
-
- //   /* close server socket on exec so CGIs can't write to it */
-//      if (fcntl(server_s, F_SETFD, 1) == -1) {
- //       printf("can't set close-on-exec on server socket!");
-//      }
-
-    /* reuse socket addr */
-        if ((setsockopt(server_s, SOL_SOCKET, SO_REUSEADDR, (void *) &sock_opt, sizeof (sock_opt))) == -1)
-        {
-        printf("setsockopt");
-        }
-
-
-        struct sockaddr_in server_sockaddr;
-        memset(&server_sockaddr, 0, sizeof server_sockaddr);
-        server_sockaddr.sin_family = PF_INET;
-
-        server_sockaddr.sin_addr.s_addr = htonl(INADDR_ANY);
-
-        server_sockaddr.sin_port = htons(nPort);
-
-        if(bind(server_s, (struct sockaddr *) &server_sockaddr, sizeof (server_sockaddr)) == -1)
-        {
-                printf("Unable to bind\r\n");
-                return -1;
-        }
-
-        if(listen(server_s, 10) == -1)
-        {
-                printf("unable to listen");
-        }
-
-        while(1)
-        {
-                ServerProcess();
-        }
-
-        return 0;
+   // Create the server socket
+   server_s = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
+   if(server_s == -1)
+   {
+      printf("unable to create socket\r\n");
+      return -1;
+   }
+
+   // Set server socket to be nonblocking
+   if(fcntl(server_s, F_SETFL, O_NONBLOCK) == -1)
+   {
+      printf("fcntl: unable to set server socket to nonblocking");
+      return -1;
+   }
+
+   // Set server to reuse socket addresses
+   if((setsockopt(server_s, SOL_SOCKET, SO_REUSEADDR, (void *) &sock_opt, sizeof (sock_opt))) == -1)
+   {
+      printf("setsockopt");
+   }
+
+   // Prepare sockaddr structure before binding
+   struct sockaddr_in server_sockaddr;
+   memset(&server_sockaddr, 0, sizeof server_sockaddr);
+   server_sockaddr.sin_family = PF_INET;
+   server_sockaddr.sin_addr.s_addr = htonl(INADDR_ANY);
+   server_sockaddr.sin_port = htons(nPort);
+
+   // Bind the socket address
+   if(bind(server_s, (struct sockaddr *) &server_sockaddr, sizeof (server_sockaddr)) == -1)
+   {
+      printf("Unable to bind\r\n");
+      return -1;
+   }
+
+   // Begin listening for clients to connect
+   if(listen(server_s, 10) == -1)
+   {
+      printf("unable to listen");
+   }
+
+   struct timespec delaytm;
+   delaytm.tv_sec = 0;
+   delaytm.tv_nsec = 8000000;
+
+   // Processing loop
+   while(1)
+   {
+      ServerProcess();
+
+      // Small time delay to help OS perform its processing at a smooth rate
+      nanosleep(&delaytm, NULL);
+   }
+
+   return 0;
 }
 
@@ -307 +347 @@
 
 
-
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