Abstracting a few features in the client and server. Adding additional overflow protection in splitting command and arguments.

cftp.c

@@ -54,7 +54,7 @@ void split_command(char *buffer, char *command, char *argument)
   memset(argument, '\0', MSGLEN);
   
   /* find everything up to the colon delimiter */
-  while(buffer[c] != '\0' && buffer[c] != ':')
+  while(buffer[c] != '\0' && buffer[c] != ':' && c < CMDLEN && d < CMDLEN)
   {
     command[d++] = buffer[c++];
   }
@@ -65,7 +65,7 @@ void split_command(char *buffer, char *command, char *argument)
     d = 0;
   }
   /* copy argument, if found */
-  while(buffer[c] != '\0')
+  while(buffer[c] != '\0' && c < MSGLEN && d < MSGLEN)
   {
     argument[d++] = buffer[c++];
   }

client.c

@@ -66,6 +66,44 @@ int connect_to_server(const char *address, int portnum)
   return skt;
 }
 
+/*
+ * Sends a message to the socket. Pass in the socket and message. Expects msg
+ * to be already validated by validate_command first! Formats response into
+ * string buffer given.
+ *
+ */
+void send_message(int skt, char *msg)
+{
+  char command[CMDLEN], argument[MSGLEN], errmsg[ERRMSGLEN];
+  memset(command, '\0', CMDLEN);
+  memset(argument, '\0', MSGLEN);
+  memset(errmsg, '\0', ERRMSGLEN);
+  
+  if(send(skt, msg, strlen(msg), 0) < 0)
+  {
+    sprintf(errmsg, "Send Error: %s", strerror(errno));
+    error(errmsg);
+  }
+  else if(recv(skt, msg, MSGLEN, 0) < 0)
+  {
+    sprintf(errmsg, "Receive Error: %s", strerror(errno));
+    error(errmsg);
+  }
+  else
+  {
+    split_command(msg, command, argument);
+    if(strlen(argument) > 0)
+    {
+      sprintf(errmsg, "Response: %s: %s", command, argument);
+    }
+    else
+    {
+      sprintf(errmsg, "Response: %s", command);
+    }
+    cdebug(errmsg);
+  }
+}
+
 /*
  * Runs the command processor to the server. Handles commands and responses.
  *
@@ -73,13 +111,10 @@ int connect_to_server(const char *address, int portnum)
 void run_client(const char *address, int portnum)
 {
   int skt;
-  char msg[MSGLEN], command[CMDLEN], argument[MSGLEN];
-  
-  /* clear strings */
+  char msg[MSGLEN];
   memset(msg, '\0', MSGLEN);
-  memset(command, '\0', MSGLEN);
-  memset(argument, '\0', MSGLEN);
   
+  /* simple informational header */
   sprintf(msg, "Using Server: %s:%d", address, portnum);
   cdebug(msg);
   memset(msg, '\0', MSGLEN);
@@ -89,33 +124,13 @@ void run_client(const char *address, int portnum)
     if(strlen(msg) > 0 && validate_command(msg))
     {
       skt = connect_to_server(address, portnum);
-      if(send(skt, msg, strlen(msg), 0) < 0)
-      {
-        sprintf(msg, "Send Error: %s", strerror(errno));
-        error(msg);
-      }
-      else if(recv(skt, msg, MSGLEN, 0) < 0)
-      {
-        sprintf(msg, "Receive Error: %s", strerror(errno));
-        error(msg);
-      }
-      else
-      {
-        split_command(msg, command, argument);
-        if(strlen(argument) > 0)
-        {
-          sprintf(msg, "Server Said: %s: %s", command, argument);
-        }
-        else
-        {
-          sprintf(msg, "Server Said: %s", command);
-        }
-      }
-      cdebug(msg);
+      send_message(skt, msg);
       close(skt);
     }
     else if(strlen(msg) > 0 && !strcmp(msg, "help"))
     {
+      sprintf(msg, "Using Server: %s:%d", address, portnum);
+      cdebug(msg);
       cdebug("Available commands:");
       cdebug(" * ping - returns an unix timestamp from the server");
       cdebug(" * get:filename - gets a file, if possible");

server.c

@@ -21,6 +21,30 @@ void sdebug(const char *msg)
   debug("Server", msg);
 }
 
+/*
+ * Handles each command received from the server. Expects that the message has
+ * been validated by validate_command first! Takes one parameter, the message
+ * from the client. The response is stored in the same buffer for return.
+ *
+ */
+void server_command(char *msg)
+{
+  char command[CMDLEN], argument[MSGLEN];
+  time_t pong;
+  memset(command, '\0', CMDLEN);
+  memset(argument, '\0', MSGLEN);
+  
+  /* get individual command and argument for processing */
+  split_command(msg, command, argument);
+  
+  /* now check each command and perform the expected results */
+  if(!strcmp(command, "ping"))
+  {
+    pong = time(NULL);
+    sprintf(msg, "Pong:%llud", (uintmax_t)pong);
+  }
+}
+
 /*
  * Proccesses a client connection and performs the necessary command. Called
  * on each connection from a client.
@@ -28,34 +52,22 @@ void sdebug(const char *msg)
  */
 void handle_client(int skt, const char *clientip)
 {
-  char buffer[MSGLEN], msg[ERRMSGLEN], command[CMDLEN], argument[MSGLEN];
-  time_t pong;
+  char buffer[MSGLEN], msg[ERRMSGLEN];
   memset(buffer, '\0', MSGLEN);
   memset(msg, '\0', ERRMSGLEN);
-  memset(command, '\0', CMDLEN);
-  memset(argument, '\0', MSGLEN);
   
   /* figure out what to do */
   if(recv(skt, buffer, MSGLEN, 0) >= 0 && validate_command(buffer))
   {
-    split_command(buffer, command, argument);
-    if(!strcmp(command, "ping"))
-    {
-      pong = time(NULL);
-      sprintf(buffer, "Pong:%llud", (uintmax_t)pong);
-    }
+    server_command(buffer);
+  }
+  else if(errno)
+  {
+    sprintf(buffer, "ERR:%s", strerror(errno));
   }
   else
   {
-    if(errno)
-    {
-      sprintf(buffer, "ERR:%s", strerror(errno));
-    }
-    else
-    {
-      sprintf(buffer, "ERR:Invalid Command");
-    }
-    error(buffer);
+    sprintf(buffer, "ERR:Invalid Command");
   }
   
   /* send message to client */