[icmp] Add support for responding to pings

src/include/gpxe/errfile.h

@@ -139,6 +139,7 @@
 #define ERRFILE_slam			( ERRFILE_NET | 0x00160000 )
 #define ERRFILE_ib_sma			( ERRFILE_NET | 0x00170000 )
 #define ERRFILE_ib_packet		( ERRFILE_NET | 0x00180000 )
+#define ERRFILE_icmp			( ERRFILE_NET | 0x00190000 )
 
 #define ERRFILE_image		      ( ERRFILE_IMAGE | 0x00000000 )
 #define ERRFILE_elf		      ( ERRFILE_IMAGE | 0x00010000 )

src/include/gpxe/icmp.h

@@ -0,0 +1,23 @@
+#ifndef _GPXE_ICMP_H
+#define _GPXE_ICMP_H
+
+/** @file
+ *
+ * ICMP protocol
+ *
+ */
+
+/** An ICMP header */
+struct icmp_header {
+	/** Type */
+	uint8_t type;
+	/** Code */
+	uint8_t code;
+	/** Checksum */
+	uint16_t chksum;
+} __attribute__ (( packed ));
+
+#define ICMP_ECHO_RESPONSE 0
+#define ICMP_ECHO_REQUEST 8
+
+#endif /* _GPXE_ICMP_H */

src/net/icmp.c

@@ -0,0 +1,101 @@
+/*
+ * Copyright (C) 2009 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <string.h>
+#include <errno.h>
+#include <gpxe/iobuf.h>
+#include <gpxe/in.h>
+#include <gpxe/tcpip.h>
+#include <gpxe/icmp.h>
+
+/** @file
+ *
+ * ICMP protocol
+ *
+ */
+
+struct tcpip_protocol icmp_protocol __tcpip_protocol;
+
+/**
+ * Process a received packet
+ *
+ * @v iobuf		I/O buffer
+ * @v st_src		Partially-filled source address
+ * @v st_dest		Partially-filled destination address
+ * @v pshdr_csum	Pseudo-header checksum
+ * @ret rc		Return status code
+ */
+static int icmp_rx ( struct io_buffer *iobuf, struct sockaddr_tcpip *st_src,
+		     struct sockaddr_tcpip *st_dest,
+		     uint16_t pshdr_csum __unused ) {
+	struct icmp_header *icmp = iobuf->data;
+	size_t len = iob_len ( iobuf );
+	unsigned int csum;
+	int rc;
+
+	/* Sanity check */
+	if ( len < sizeof ( *icmp ) ) {
+		DBG ( "ICMP packet too short at %zd bytes (min %zd bytes)\n",
+		      len, sizeof ( *icmp ) );
+		rc = -EINVAL;
+		goto done;
+	}
+
+	/* Verify checksum */
+	csum = tcpip_chksum ( icmp, len );
+	if ( csum != 0 ) {
+		DBG ( "ICMP checksum incorrect (is %04x, should be 0000)\n",
+		      csum );
+		DBG_HD ( icmp, len );
+		rc = -EINVAL;
+		goto done;
+	}
+
+	/* We respond only to pings */
+	if ( icmp->type != ICMP_ECHO_REQUEST ) {
+		DBG ( "ICMP ignoring type %d\n", icmp->type );
+		rc = 0;
+		goto done;
+	}
+
+	DBG ( "ICMP responding to ping\n" );
+
+	/* Change type to response and recalculate checksum */
+	icmp->type = ICMP_ECHO_RESPONSE;
+	icmp->chksum = 0;
+	icmp->chksum = tcpip_chksum ( icmp, len );
+
+	/* Transmit the response */
+	if ( ( rc = tcpip_tx ( iob_disown ( iobuf ), &icmp_protocol, st_dest,
+			       st_src, NULL, NULL ) ) != 0 ) {
+		DBG ( "ICMP could not transmit ping response: %s\n",
+		      strerror ( rc ) );
+		goto done;
+	}
+
+ done:
+	free_iob ( iobuf );
+	return rc;
+}
+
+/** ICMP TCP/IP protocol */
+struct tcpip_protocol icmp_protocol __tcpip_protocol = {
+	.name = "ICMP",
+	.rx = icmp_rx,
+	.tcpip_proto = IP_ICMP,
+};

src/net/ipv4.c

@@ -627,3 +627,6 @@ static int ipv4_create_routes ( void ) {
 struct settings_applicator ipv4_settings_applicator __settings_applicator = {
 	.apply = ipv4_create_routes,
 };
+
+/* Drag in ICMP */
+REQUIRE_OBJECT ( icmp );