Fix filling msghdr for sendmsg (#977)

* Fix filling msghdr for sendmsg

* Split nasl_dump_frame

* Change log messages from debug to message level

nasl/nasl_frame_forgery.c

@@ -67,6 +67,28 @@ struct pseudo_frame
   u_char *payload;
 } __attribute__ ((packed));
 
+/** @brief Dump a datalink layer frame
+ *
+ * @param frame    The frame to be dumped.
+ * @param frame_sz The frame's size.
+ *
+ */
+static void
+dump_frame (const u_char *frame, int frame_sz)
+{
+  int f = 0;
+
+  printf ("\nThe Frame:\n");
+  while (f < frame_sz)
+    {
+      printf ("%02x%02x ", ((u_char *) frame)[f], ((u_char *) frame)[f + 1]);
+      f += 2;
+      if (f % 16 == 0)
+        printf ("\n");
+    }
+  printf ("\n\n");
+}
+
 /** @brief Prepare message header to be sent with sendmsg().
  *
  * @param[out] soc_addr_ll The sockaddr_ll structure to be prepared
@@ -86,25 +108,32 @@ prepare_sockaddr_ll (struct sockaddr_ll *soc_addr_ll, int ifindex,
 
 /** @brief Prepare message header to be sent with sendmsg().
  *
- * @param[out] message The packaged messages to be sent
+ * @param[out] msg The packaged messages to be sent
  * @param[in] soc_addr_ll The sockaddr_ll structure for capturing
  * @param[in] payload The payload, a datalink layer frame with payload
  * @param[in] payload_sz The payload size.
  */
 static void
-prepare_message (struct msghdr *message, struct sockaddr_ll *soc_addr_ll,
-                 u_char *payload, int payload_sz)
+prepare_message (u_char *msg, struct sockaddr_ll *soc_addr_ll, u_char *payload,
+                 int payload_sz)
 {
-  struct iovec iov[1];
-  iov[0].iov_base = payload;
-  iov[0].iov_len = payload_sz;
+  struct iovec iov;
+  struct msghdr *message;
+
+  iov.iov_base = payload;
+  iov.iov_len = payload_sz;
+
+  message = g_malloc0 (sizeof (struct msghdr) + payload_sz);
 
   message->msg_name = soc_addr_ll;
   message->msg_namelen = sizeof (struct sockaddr_ll);
-  message->msg_iov = iov;
+  message->msg_iov = &iov;
   message->msg_iovlen = 1;
   message->msg_control = 0;
   message->msg_controllen = 0;
+
+  memcpy (msg, (u_char *) message, sizeof (struct msghdr) + payload_sz);
+  g_free (message);
 }
 
 /** @brief Send a frame and listen to the answer
@@ -127,7 +156,7 @@ send_frame (const u_char *frame, int frame_sz, int use_pcap, int timeout,
             char *filter, struct in6_addr *ipaddr, u_char **answer)
 {
   int soc;
-  struct msghdr message;
+  u_char *message;
   int ifindex;
   int bpf = -1;
   int frame_and_payload = 0;
@@ -144,7 +173,7 @@ send_frame (const u_char *frame, int frame_sz, int use_pcap, int timeout,
   // We will need the eth index. We get it depending on the target's IP..
   if (get_iface_index (ipaddr, &ifindex) < 0)
     {
-      g_debug ("%s: Missing interface index\n", __func__);
+      g_message ("%s: Missing interface index\n", __func__);
       return -1;
     }
 
@@ -176,13 +205,14 @@ send_frame (const u_char *frame, int frame_sz, int use_pcap, int timeout,
     }
 
   // Prepare the message and send it
-  memset (&message, '\0', sizeof (struct msghdr));
-  prepare_message (&message, &soc_addr, (u_char *) frame, frame_sz);
+  message = g_malloc0 (sizeof (struct msghdr) + frame_sz);
+  prepare_message (message, &soc_addr, (u_char *) frame, frame_sz);
 
-  int b = sendmsg (soc, &message, 0);
+  int b = sendmsg (soc, (struct msghdr *) message, 0);
+  g_free (message);
   if (b == -1)
     {
-      g_debug ("%s: Error sending message: %s", __func__, strerror (errno));
+      g_message ("%s: Error sending message: %s", __func__, strerror (errno));
       return -2;
     }
   if (bpf >= 0)
@@ -348,7 +378,6 @@ nasl_dump_frame (lex_ctxt *lexic)
 {
   u_char *frame = (u_char *) get_str_var_by_name (lexic, "frame");
   int frame_sz = get_var_size_by_name (lexic, "frame");
-  int f = 0;
 
   if (frame == NULL || frame_sz <= 0)
     {
@@ -357,19 +386,7 @@ nasl_dump_frame (lex_ctxt *lexic)
       return NULL;
     }
 
-  if (frame_sz == 0)
-    return NULL;
-
-  printf ("\nThe Frame:\n");
-  while (f < frame_sz)
-    {
-      printf ("%02x%02x ", ((u_char *) frame)[f], ((u_char *) frame)[f + 1]);
-      f += 2;
-      if (f % 16 == 0)
-        printf ("\n");
-    }
-  printf ("\n\n");
-
+  dump_frame (frame, frame_sz);
   return NULL;
 }