Update TCP proxy to address Coverity errors

Coverity seems to have some problems with the loop(s) copying data from
one socket to another, in that it assume that eventually an integer
overflow will occur. It's not obvious why this should be flagged, but
this seems likely to be a false positive.

This commit avoids the integer issue by using a simple pointer + count
mechanism.

The socket copy code has been placed in a separate function - before it
was duplicated. Minor fixes have been made to error reporting around the
connection code.

tools/devel/tcp_proxy/main.c

@@ -43,8 +43,6 @@ int  g_loc_io_count = 0;  // bytes read from local port
 int  g_rem_io_count = 0;  // bytes read from remote port
 
 static int g_terminated = 0;
-static char g_buf[1024 * 32];
-
 
 typedef unsigned short tui16;
 
@@ -67,6 +65,69 @@ g_tcp_socket_ok(int sck)
     return 0;
 }
 
+/*****************************************************************************/
+static int
+copy_sck_to_sck(int from_sck, int to_sck, int hexdump, int local)
+{
+    char buff[1024 * 32];
+    int rv = -1;
+
+    int count = g_tcp_recv(from_sck, buff, sizeof(buff), 0);
+    if (count > 0 && count <= (int)sizeof(buff))
+    {
+        rv = count; // Assume we'll return the amount of data copied
+        if (local)
+        {
+            g_loc_io_count += count;
+            if (hexdump)
+            {
+                LOG_HEXDUMP(LOG_LEVEL_INFO, "from local:", buff, count);
+            }
+        }
+        else
+        {
+            g_rem_io_count += count;
+            if (hexdump)
+            {
+                LOG_HEXDUMP(LOG_LEVEL_INFO, "from remote:", buff, count);
+            }
+        }
+
+
+        LOG(LOG_LEVEL_DEBUG, "local_io_count: %d\tremote_io_count: %d",
+            g_loc_io_count, g_rem_io_count);
+
+        const char *p = buff;
+        while ((count > 0) && (!g_terminated))
+        {
+            int error = g_tcp_send(to_sck, p, count, 0);
+
+            if (error > 0)
+            {
+                // We wrote some data
+                count -= error;
+                p += error;
+                continue;
+            }
+
+            if ((error == -1) && g_tcp_last_error_would_block(to_sck))
+            {
+                if (g_tcp_can_send(to_sck, 1000))
+                {
+                    g_tcp_socket_ok(to_sck);
+                }
+            }
+            else
+            {
+                count = 0; // Terminate loop
+                rv = -1; // tell user
+            }
+        }
+    }
+
+    return rv;
+}
+
 /*****************************************************************************/
 static int
 main_loop(char *local_port, char *remote_ip, char *remote_port, int hexdump)
@@ -76,7 +137,6 @@ main_loop(char *local_port, char *remote_ip, char *remote_port, int hexdump)
     int con_sck = -1;
     int sel;
     int count;
-    int sent;
     int error;
     int i;
     int acc_to_con = 0;
@@ -165,9 +225,8 @@ main_loop(char *local_port, char *remote_ip, char *remote_port, int hexdump)
             error = 0;
             i = 0;
 
-            while (!(g_tcp_can_send(con_sck, 100) && g_tcp_socket_ok(con_sck))
-                    && (!g_terminated)
-                    && (i < 100))
+            while (!g_terminated && i < 100 &&
+                    !g_tcp_can_send(con_sck, 100))
             {
                 g_sleep(100);
                 i++;
@@ -178,8 +237,7 @@ main_loop(char *local_port, char *remote_ip, char *remote_port, int hexdump)
                 LOG(LOG_LEVEL_ERROR, "timeout connecting");
                 error = 1;
             }
-
-            if (g_terminated)
+            else if (!g_tcp_socket_ok(con_sck))
             {
                 error = 1;
             }
@@ -191,7 +249,7 @@ main_loop(char *local_port, char *remote_ip, char *remote_port, int hexdump)
         }
     }
 
-    while ((!g_terminated) && (error == 0))
+    while (!g_terminated)
     {
         sel = g_tcp_select(con_sck, acc_sck);
 
@@ -204,87 +262,22 @@ main_loop(char *local_port, char *remote_ip, char *remote_port, int hexdump)
         if (sel & 1)
         {
             // can read from con_sck w/o blocking
-            count = g_tcp_recv(con_sck, g_buf, 1024 * 16, 0);
-            error = count < 1;
-
-            if (error == 0)
+            count = copy_sck_to_sck(con_sck, acc_sck, hexdump, 1);
+            if (count < 0)
             {
-                g_loc_io_count += count;
-                con_to_acc += count;
-
-                if (hexdump)
-                {
-                    LOG_HEXDUMP(LOG_LEVEL_INFO, "from remove, the socket from connect", g_buf, count);
-                }
-
-                LOG(LOG_LEVEL_DEBUG, "local_io_count: %d\tremote_io_count: %d",
-                    g_loc_io_count, g_rem_io_count);
-                sent = 0;
-
-                while ((sent < count) && (error == 0) && (!g_terminated))
-                {
-                    i = g_tcp_send(acc_sck, g_buf + sent, count - sent, 0);
-
-                    if ((i == -1) && g_tcp_last_error_would_block(acc_sck))
-                    {
-                        if (g_tcp_can_send(acc_sck, 1000))
-                        {
-                            g_tcp_socket_ok(acc_sck);
-                        }
-                    }
-                    else if (i < 1)
-                    {
-                        error = 1;
-                    }
-                    else
-                    {
-                        sent += i;
-                    }
-                }
+                break;
             }
+            con_to_acc += count;
         }
-
         if (sel & 2)
         {
             // can read from acc_sck w/o blocking
-            count = g_tcp_recv(acc_sck, g_buf, 1024 * 16, 0);
-            error = count < 1;
-
-            if (error == 0)
+            count = copy_sck_to_sck(acc_sck, con_sck, hexdump, 0);
+            if (count < 0)
             {
-                g_rem_io_count += count;
-                acc_to_con += count;
-
-                if (hexdump)
-                {
-                    LOG_HEXDUMP(LOG_LEVEL_INFO, "from accepted, the socket from accept", g_buf, count);
-                }
-
-                LOG(LOG_LEVEL_DEBUG, "local_io_count: %d\tremote_io_count: %d",
-                    g_loc_io_count, g_rem_io_count);
-                sent = 0;
-
-                while ((sent < count) && (error == 0) && (!g_terminated))
-                {
-                    i = g_tcp_send(con_sck, g_buf + sent, count - sent, 0);
-
-                    if ((i == -1) && g_tcp_last_error_would_block(con_sck))
-                    {
-                        if (g_tcp_can_send(con_sck, 1000))
-                        {
-                            g_tcp_socket_ok(con_sck);
-                        }
-                    }
-                    else if (i < 1 || i > (count - sent))
-                    {
-                        error = 1;
-                    }
-                    else
-                    {
-                        sent += i;
-                    }
-                }
-            }
+                break;
+            };
+            acc_to_con += count;
         }
     }