From 6e89e545b3302689c367505c5bc7d0ceea2a1c9f Mon Sep 17 00:00:00 2001
From: adamdunkels <adamdunkels>
Date: Thu, 24 Jan 2008 23:08:58 +0000
Subject: [PATCH] Added optional transmission of ICMP destimation unreachable
 in response to incoming UDP packets with an destination port that is not
 open. This is needed for correct operation of traceroute

---
 core/net/uip.c | 35 ++++++++++++++++++++++++++++++++++-
 core/net/uip.h |  3 ++-
 2 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/core/net/uip.c b/core/net/uip.c
index 2dcfa1e21..b843da5a7 100644
--- a/core/net/uip.c
+++ b/core/net/uip.c
@@ -41,7 +41,7 @@
  *
  * This file is part of the uIP TCP/IP stack.
  *
- * $Id: uip.c,v 1.9 2007/11/28 12:53:07 adamdunkels Exp $
+ * $Id: uip.c,v 1.10 2008/01/24 23:08:58 adamdunkels Exp $
  *
  */
 
@@ -196,6 +196,9 @@ static u16_t tmp16;
 #define ICMP_ECHO_REPLY 0
 #define ICMP_ECHO       8
 
+#define ICMP_DEST_UNREACHABLE        3
+#define ICMP_PORT_UNREACHABLE        3
+
 #define ICMP6_ECHO_REPLY             129
 #define ICMP6_ECHO                   128
 #define ICMP6_NEIGHBOR_SOLICITATION  135
@@ -1104,7 +1107,37 @@ uip_process(u8_t flag)
     }
   }
   UIP_LOG("udp: no matching connection found");
+#if UIP_CONF_ICMP_DEST_UNREACH && !UIP_CONF_IPV6
+  /* Copy fields from packet header into payload of this ICMP packet. */
+  memcpy(&(ICMPBUF->payload[0]), ICMPBUF, UIP_IPH_LEN + 8);
+
+  /* Set the ICMP type and code. */
+  ICMPBUF->type = ICMP_DEST_UNREACHABLE;
+  ICMPBUF->icode = ICMP_PORT_UNREACHABLE;
+
+  /* Calculate the ICMP checksum. */
+  ICMPBUF->icmpchksum = 0;
+  ICMPBUF->icmpchksum = ~uip_chksum((u16_t *)&(ICMPBUF->type), 36);
+
+  /* Set the IP destination address to be the source address of the
+     original packet. */
+  uip_ipaddr_copy(&BUF->destipaddr, &BUF->srcipaddr);
+
+  /* Set our IP address as the source address. */
+  uip_ipaddr_copy(&BUF->srcipaddr, &uip_hostaddr);
+
+  /* The size of the ICMP destination unreachable packet is 36 + the
+     size of the IP header (20) = 56. */
+  uip_len = 36 + UIP_IPH_LEN;
+  ICMPBUF->len[0] = 0;
+  ICMPBUF->len[1] = (u8_t)uip_len;
+  ICMPBUF->ttl = UIP_TTL;
+  ICMPBUF->proto = UIP_PROTO_ICMP;
+
+  goto ip_send_nolen;
+#else /* UIP_CONF_ICMP_DEST_UNREACH */
   goto drop;
+#endif /* UIP_CONF_ICMP_DEST_UNREACH */
   
  udp_found:
   uip_conn = NULL;
diff --git a/core/net/uip.h b/core/net/uip.h
index 477817dad..e5688b570 100644
--- a/core/net/uip.h
+++ b/core/net/uip.h
@@ -46,7 +46,7 @@
  *
  * This file is part of the uIP TCP/IP stack.
  *
- * $Id: uip.h,v 1.13 2007/11/28 12:52:12 adamdunkels Exp $
+ * $Id: uip.h,v 1.14 2008/01/24 23:08:58 adamdunkels Exp $
  *
  */
 
@@ -1497,6 +1497,7 @@ struct uip_icmpip_hdr {
   u16_t icmpchksum;
 #if !UIP_CONF_IPV6
   u16_t id, seqno;
+  u8_t payload[1];
 #else /* !UIP_CONF_IPV6 */
   u8_t flags, reserved1, reserved2, reserved3;
   u8_t icmp6data[16];