1 files changed, 42 insertions, 12 deletions

diff --git a/src/nat/gnunet-helper-nat-client.c b/src/nat/gnunet-helper-nat-client.c
index d9129afb0..359e529b0 100644
--- a/src/nat/gnunet-helper-nat-client.c
+++ b/src/nat/gnunet-helper-nat-client.c
@@ -67,6 +67,17 @@
 #endif
 
 /**
+ * Call memcpy() but check for @a n being 0 first. In the latter
+ * case, it is now safe to pass NULL for @a src or @a dst.
+ * Unlike traditional memcpy(), returns nothing.
+ *
+ * @param dst destination of the copy, may be NULL if @a n is zero
+ * @param src source of the copy, may be NULL if @a n is zero
+ * @param n number of bytes to copy
+ */
+#define GNUNET_memcpy(dst,src,n) do { if (0 != n) { (void) memcpy (dst,src,n); } } while (0)
+
+/**
  * Must match IP given in the server.
  */
 #define DUMMY_IP "192.0.2.86"
@@ -251,14 +262,18 @@ send_icmp_udp (const struct in_addr *my_ip, const struct in_addr *other)
   ip_pkt.dst_ip = other->s_addr;
   ip_pkt.checksum =
       htons (calc_checksum ((uint16_t *) & ip_pkt, sizeof (struct ip_header)));
-  memcpy (&packet[off], &ip_pkt, sizeof (struct ip_header));
+  GNUNET_memcpy (&packet[off],
+                 &ip_pkt,
+                 sizeof (struct ip_header));
   off += sizeof (struct ip_header);
 
   icmp_pkt.type = ICMP_TIME_EXCEEDED;
   icmp_pkt.code = 0;
   icmp_pkt.checksum = 0;
   icmp_pkt.unused = 0;
-  memcpy (&packet[off], &icmp_pkt, sizeof (struct icmp_ttl_exceeded_header));
+  GNUNET_memcpy (&packet[off],
+                 &icmp_pkt,
+                 sizeof (struct icmp_ttl_exceeded_header));
   off += sizeof (struct icmp_ttl_exceeded_header);
 
   /* ip header of the presumably 'lost' udp packet */
@@ -275,7 +290,9 @@ send_icmp_udp (const struct in_addr *my_ip, const struct in_addr *other)
   ip_pkt.dst_ip = dummy.s_addr;
   ip_pkt.checksum =
       htons (calc_checksum ((uint16_t *) & ip_pkt, sizeof (struct ip_header)));
-  memcpy (&packet[off], &ip_pkt, sizeof (struct ip_header));
+  GNUNET_memcpy (&packet[off],
+                 &ip_pkt,
+                 sizeof (struct ip_header));
   off += sizeof (struct ip_header);
 
   /* build UDP header */
@@ -283,7 +300,9 @@ send_icmp_udp (const struct in_addr *my_ip, const struct in_addr *other)
   udp_pkt.dst_port = htons (NAT_TRAV_PORT);
   udp_pkt.length = htons (port);
   udp_pkt.crc = 0;
-  memcpy (&packet[off], &udp_pkt, sizeof (struct udp_header));
+  GNUNET_memcpy (&packet[off],
+                 &udp_pkt,
+                 sizeof (struct udp_header));
   off += sizeof (struct udp_header);
 
   /* set ICMP checksum */
@@ -292,8 +311,9 @@ send_icmp_udp (const struct in_addr *my_ip, const struct in_addr *other)
              ((uint16_t *) & packet[sizeof (struct ip_header)],
               sizeof (struct icmp_ttl_exceeded_header) +
               sizeof (struct ip_header) + sizeof (struct udp_header)));
-  memcpy (&packet[sizeof (struct ip_header)], &icmp_pkt,
-          sizeof (struct icmp_ttl_exceeded_header));
+  GNUNET_memcpy (&packet[sizeof (struct ip_header)],
+                 &icmp_pkt,
+                 sizeof (struct icmp_ttl_exceeded_header));
 
   memset (&dst, 0, sizeof (dst));
   dst.sin_family = AF_INET;
@@ -352,7 +372,9 @@ send_icmp (const struct in_addr *my_ip, const struct in_addr *other)
   ip_pkt.dst_ip = other->s_addr;
   ip_pkt.checksum =
       htons (calc_checksum ((uint16_t *) & ip_pkt, sizeof (struct ip_header)));
-  memcpy (&packet[off], &ip_pkt, sizeof (struct ip_header));
+  GNUNET_memcpy (&packet[off],
+                 &ip_pkt,
+                 sizeof (struct ip_header));
   off = sizeof (ip_pkt);
 
   /* icmp reply: time exceeded */
@@ -360,7 +382,9 @@ send_icmp (const struct in_addr *my_ip, const struct in_addr *other)
   icmp_ttl.code = 0;
   icmp_ttl.checksum = 0;
   icmp_ttl.unused = 0;
-  memcpy (&packet[off], &icmp_ttl, sizeof (struct icmp_ttl_exceeded_header));
+  GNUNET_memcpy (&packet[off],
+                 &icmp_ttl,
+                 sizeof (struct icmp_ttl_exceeded_header));
   off += sizeof (struct icmp_ttl_exceeded_header);
 
   /* ip header of the presumably 'lost' udp packet */
@@ -377,7 +401,9 @@ send_icmp (const struct in_addr *my_ip, const struct in_addr *other)
   ip_pkt.checksum = 0;
   ip_pkt.checksum =
       htons (calc_checksum ((uint16_t *) & ip_pkt, sizeof (struct ip_header)));
-  memcpy (&packet[off], &ip_pkt, sizeof (struct ip_header));
+  GNUNET_memcpy (&packet[off],
+                 &ip_pkt,
+                 sizeof (struct ip_header));
   off += sizeof (struct ip_header);
 
   icmp_echo.type = ICMP_ECHO;
@@ -386,8 +412,10 @@ send_icmp (const struct in_addr *my_ip, const struct in_addr *other)
   icmp_echo.checksum = 0;
   icmp_echo.checksum =
       htons (calc_checksum
-             ((uint16_t *) & icmp_echo, sizeof (struct icmp_echo_header)));
-  memcpy (&packet[off], &icmp_echo, sizeof (struct icmp_echo_header));
+             ((uint16_t *) &icmp_echo, sizeof (struct icmp_echo_header)));
+  GNUNET_memcpy (&packet[off],
+                 &icmp_echo,
+                 sizeof (struct icmp_echo_header));
 
   /* no go back to calculate ICMP packet checksum */
   off = sizeof (struct ip_header);
@@ -396,7 +424,9 @@ send_icmp (const struct in_addr *my_ip, const struct in_addr *other)
              ((uint16_t *) & packet[off],
               sizeof (struct icmp_ttl_exceeded_header) +
               sizeof (struct ip_header) + sizeof (struct icmp_echo_header)));
-  memcpy (&packet[off], &icmp_ttl, sizeof (struct icmp_ttl_exceeded_header));
+  GNUNET_memcpy (&packet[off],
+                 &icmp_ttl,
+                 sizeof (struct icmp_ttl_exceeded_header));
 
   /* prepare for transmission */
   memset (&dst, 0, sizeof (dst));