Added option CHECKSUM_GEN_ICMP

CHANGELOG

@@ -6,6 +6,9 @@ HISTORY
 
  ++ New features:
 
+  2012-01-16: Simon Goldschmidt
+  * opt.h, icmp.c: Added option CHECKSUM_GEN_ICMP
+
   2011-07-21: Simon Goldschmidt (patch by hanhui)
   * ip4.c, etharp.c, pbuf.h: bug #33634 ip_forward() have a faulty behaviour:
     Added pbuf flags to mark incoming packets as link-layer broadcast/multicast.

src/core/ipv4/icmp.c

@@ -190,12 +190,16 @@ icmp_input(struct pbuf *p, struct netif *inp)
     ip_addr_copy(iphdr->src, *ip_current_dest_addr());
     ip_addr_copy(iphdr->dest, *ip_current_src_addr());
     ICMPH_TYPE_SET(iecho, ICMP_ER);
+#if CHECKSUM_GEN_ICMP
     /* adjust the checksum */
     if (iecho->chksum >= PP_HTONS(0xffffU - (ICMP_ECHO << 8))) {
       iecho->chksum += PP_HTONS(ICMP_ECHO << 8) + 1;
     } else {
       iecho->chksum += PP_HTONS(ICMP_ECHO << 8);
     }
+#else /* CHECKSUM_GEN_ICMP */
+    iecho->chksum = 0;
+#endif /* CHECKSUM_GEN_ICMP */
 
     /* Set the correct TTL and recalculate the header checksum. */
     IPH_TTL_SET(iphdr, ICMP_TTL);

src/include/lwip/opt.h

@@ -1802,6 +1802,13 @@
 #ifndef CHECKSUM_GEN_TCP
 #define CHECKSUM_GEN_TCP                1
 #endif
+
+/**
+ * CHECKSUM_GEN_ICMP==1: Generate checksums in software for outgoing ICMP packets.
+ */
+#ifndef CHECKSUM_GEN_ICMP
+#define CHECKSUM_GEN_ICMP               1
+#endif
  
 /**
  * CHECKSUM_CHECK_IP==1: Check checksums in software for incoming IP packets.