net: tftpput: Add support for receiving ICMP packets

ICMP packets can tell you when there is no server at the other end. It
is useful for tftp to figure this out, so that a quick error can be
displayed, rather than pointlessly retrying.

This adds an ICMP packet handler to the net interface.

Signed-off-by: Simon Glass <sjg@chromium.org>

include/net.h

@@ -48,6 +48,19 @@ typedef void rxhand_f(uchar *pkt, unsigned dport,
 		      IPaddr_t sip, unsigned sport,
 		      unsigned len);
 
+/**
+ * An incoming ICMP packet handler.
+ * @param type	ICMP type
+ * @param code	ICMP code
+ * @param dport	destination UDP port
+ * @param sip	source IP address
+ * @param sport	source UDP port
+ * @param pkt	pointer to the ICMP packet data
+ * @param len	packet length
+ */
+typedef void rxhand_icmp_f(unsigned type, unsigned code, unsigned dport,
+		IPaddr_t sip, unsigned sport, uchar *pkt, unsigned len);
+
 /*
  *	A timeout handler.  Called after time interval has expired.
  */
@@ -244,6 +257,7 @@ typedef struct
  * ICMP stuff (just enough to handle (host) redirect messages)
  */
 #define ICMP_ECHO_REPLY		0	/* Echo reply			*/
+#define ICMP_NOT_REACH		3	/* Detination unreachable	*/
 #define ICMP_REDIRECT		5	/* Redirect (change route)	*/
 #define ICMP_ECHO_REQUEST	8	/* Echo request			*/
 
@@ -251,6 +265,9 @@ typedef struct
 #define ICMP_REDIR_NET		0	/* Redirect Net			*/
 #define ICMP_REDIR_HOST		1	/* Redirect Host		*/
 
+/* Codes for NOT_REACH */
+#define ICMP_NOT_REACH_PORT	3	/* Port unreachable		*/
+
 typedef struct icmphdr {
 	uchar		type;
 	uchar		code;
@@ -265,6 +282,7 @@ typedef struct icmphdr {
 			ushort	__unused;
 			ushort	mtu;
 		} frag;
+		uchar data[0];
 	} un;
 } ICMP_t;
 
@@ -397,6 +415,7 @@ extern uint	NetCksum(uchar *, int);		/* Calculate the checksum	*/
 
 /* Set callbacks */
 extern void	NetSetHandler(rxhand_f *);	/* Set RX packet handler	*/
+extern void net_set_icmp_handler(rxhand_icmp_f *f); /* Set ICMP RX handler */
 extern void	NetSetTimeout(ulong, thand_f *);/* Set timeout handler		*/
 
 /* Transmit "NetTxPacket" */

net/net.c

@@ -215,6 +215,7 @@ volatile uchar *NetRxPackets[PKTBUFSRX];
 
 /* Current RX packet handler */
 static rxhand_f *packetHandler;
+static rxhand_icmp_f *packet_icmp_handler;	/* Current ICMP rx handler */
 /* Current timeout handler */
 static thand_f *timeHandler;
 /* Time base value */
@@ -344,6 +345,7 @@ int
 NetLoop(proto_t protocol)
 {
 	bd_t *bd = gd->bd;
+	int ret = -1;
 
 	NetRestarted = 0;
 	NetDevExists = 0;
@@ -512,7 +514,7 @@ restart:
 		if (ctrlc()) {
 			eth_halt();
 			puts("\nAbort\n");
-			return -1;
+			goto done;
 		}
 
 		ArpTimeoutCheck();
@@ -564,12 +566,19 @@ restart:
 				setenv("fileaddr", buf);
 			}
 			eth_halt();
-			return NetBootFileXferSize;
+			ret = NetBootFileXferSize;
+			goto done;
 
 		case NETLOOP_FAIL:
-			return -1;
+			goto done;
 		}
 	}
+
+done:
+	/* Clear out the handlers */
+	NetSetHandler(NULL);
+	net_set_icmp_handler(NULL);
+	return ret;
 }
 
 /**********************************************************************/
@@ -643,6 +652,10 @@ NetSetHandler(rxhand_f *f)
 	packetHandler = f;
 }
 
+void net_set_icmp_handler(rxhand_icmp_f *f)
+{
+	packet_icmp_handler = f;
+}
 
 void
 NetSetTimeout(ulong iv, thand_f *f)
@@ -1383,6 +1396,10 @@ static void receive_icmp(IP_t *ip, int len, IPaddr_t src_ip, Ethernet_t *et)
 		break;
 #endif
 	default:
+		if (packet_icmp_handler)
+			packet_icmp_handler(icmph->type, icmph->code,
+				ntohs(ip->udp_dst), src_ip, ntohs(ip->udp_src),
+				icmph->un.data, ntohs(ip->udp_len));
 		break;
 	}
 }
@@ -1671,6 +1688,10 @@ NetReceive(volatile uchar *inpkt, int len)
 		 * subnet. So this is probably a warning that your
 		 * configuration might be wrong. But I'm not really
 		 * sure if there aren't any other situations.
+		 *
+		 * Simon Glass <sjg@chromium.org>: We get an ICMP when
+		 * we send a tftp packet to a dead connection, or when
+		 * there is no server at the other end.
 		 */
 		if (ip->ip_p == IPPROTO_ICMP) {
 			receive_icmp(ip, len, src_ip, et);