A working name resolution framework

src/config.h

@@ -72,7 +72,7 @@
 
 #define	DOWNLOAD_PROTO_TFTP	/* Trivial File Transfer Protocol */
 #undef	DOWNLOAD_PROTO_NFS	/* Network File System */
-#undef	DOWNLOAD_PROTO_HTTP	/* Hypertext Transfer Protocol */
+#define	DOWNLOAD_PROTO_HTTP	/* Hypertext Transfer Protocol */
 #undef	DOWNLOAD_PROTO_TFTM	/* Multicast Trivial File Transfer Protocol */
 #undef	DOWNLOAD_PROTO_SLAM	/* Scalable Local Area Multicast */
 #undef	DOWNLOAD_PROTO_FSP	/* FSP? */
@@ -85,7 +85,7 @@
  *
  */
 
-#undef	DNS_RESOLVER		/* DNS resolver */
+#define	DNS_RESOLVER		/* DNS resolver */
 #undef	NMB_RESOLVER		/* NMB resolver */
 
 /* @END general.h */

src/core/resolv.c

@@ -1,33 +1,134 @@
-#include "resolv.h"
+/*
+ * Copyright (C) 2007 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 <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <gpxe/in.h>
+#include <gpxe/resolv.h>
 
+/** @file
+ *
+ * Name resolution
+ *
+ */
+
+static struct async_operations resolv_async_operations;
+
+/** Registered name resolvers */
 static struct resolver resolvers[0]
-	__table_start ( struct resolver, resolver );
+	__table_start ( struct resolver, resolvers );
 static struct resolver resolvers_end[0]
-	__table_end ( struct resolver, resolver );
+	__table_end ( struct resolver, resolvers );
 
-/*
- * Resolve a name (which may be just a dotted quad IP address) to an
- * IP address.
+/**
+ * Start name resolution
  *
+ * @v name		Host name to resolve
+ * @v sa		Socket address to fill in
+ * @v parent		Parent asynchronous operation
+ * @ret rc		Return status code
  */
-int resolv ( struct in_addr *address, const char *name ) {
+int resolv ( const char *name, struct sockaddr *sa, struct async *parent ) {
+	struct resolution *resolution;
 	struct resolver *resolver;
+	struct sockaddr_in *sin = ( struct sockaddr_in * ) sa;
+	struct in_addr in;
+	int rc = -ENXIO;
+
+	/* Allocate and populate resolution structure */
+	resolution = malloc ( sizeof ( *resolution ) );
+	if ( ! resolution )
+		return -ENOMEM;
+	async_init ( &resolution->async, &resolv_async_operations, parent );
 
 	/* Check for a dotted quad IP address first */
-	if ( inet_aton ( name, address ) ) {
-		DBG ( "RESOLV saw valid IP address %s\n", name );
-		return 1;
+	if ( inet_aton ( name, &in ) != 0 ) {
+		DBGC ( resolution, "RESOLV %p saw valid IP address %s\n",
+		       resolution, name );
+		sin->sin_family = AF_INET;
+		sin->sin_addr = in;
+		async_done ( &resolution->async, 0 );
+		return 0;
 	}
 
-	/* Try any compiled-in name resolution modules */
+	/* Start up all resolvers */
 	for ( resolver = resolvers ; resolver < resolvers_end ; resolver++ ) {
-		if ( resolver->resolv ( address, name ) ) {
-			DBG ( "RESOLV resolved \"%s\" to %@ using %s\n",
-			      name, address->s_addr, resolver->name );
-			return 1;
+		if ( ( rc = resolver->resolv ( name, sa,
+					       &resolution->async ) ) != 0 ) {
+			DBGC ( resolution, "RESOLV %p could not start %s: "
+			       "%s\n", resolution, resolver->name,
+			       strerror ( rc ) );
+			/* Continue to try other resolvers */
+			continue;
 		}
+		(resolution->pending)++;
 	}
+	if ( ! resolution->pending )
+		goto err;
 
-	DBG ( "RESOLV failed to resolve %s\n", name );
 	return 0;
+
+ err:
+	async_uninit ( &resolution->async );
+	free ( resolution );
+	return rc;
 }
+
+/**
+ * Handle child name resolution completion
+ *
+ * @v async		Name resolution asynchronous operation
+ * @v signal		SIGCHLD
+ */
+static void resolv_sigchld ( struct async *async,
+			     enum signal signal __unused ) {
+	struct resolution *resolution =
+		container_of ( async, struct resolution, async );
+	int rc;
+
+	/* If this child succeeded, kill all the others and return */
+	async_wait ( async, &rc, 1 );
+	if ( rc == 0 ) {
+		async_signal_children ( async, SIGKILL );
+		async_done ( async, 0 );
+		return;
+	}
+
+	/* If we have no children left, return failure */
+	if ( --(resolution->pending) == 0 )
+		async_done ( async, -ENXIO );
+}
+
+/**
+ * Free name resolution structure
+ *
+ * @v async		Asynchronous operation
+ */
+static void resolv_reap ( struct async *async ) {
+	free ( container_of ( async, struct resolution, async ) );
+}
+
+/** Name resolution asynchronous operations */
+static struct async_operations resolv_async_operations = {
+	.reap = resolv_reap,
+	.signal = {
+		[SIGCHLD] = resolv_sigchld,
+	},
+};

src/include/gpxe/resolv.h

@@ -0,0 +1,47 @@
+#ifndef _GPXE_RESOLV_H
+#define _GPXE_RESOLV_H
+
+/** @file
+ *
+ * Name resolution
+ *
+ */
+
+struct sockaddr;
+
+#include <gpxe/async.h>
+#include <gpxe/tables.h>
+
+/** A name resolver */
+struct resolver {
+	/** Name of this resolver (e.g. "DNS") */
+	const char *name;
+	/** Start name resolution
+	 *
+	 * @v name		Host name to resolve
+	 * @v sa		Socket address to fill in
+	 * @v parent		Parent asynchronous operation
+	 * @ret rc		Return status code
+	 *
+	 * The asynchronous process must be prepared to accept
+	 * SIGKILL.
+	 */
+	int ( * resolv ) ( const char *name, struct sockaddr *sa,
+			   struct async *parent );
+};
+
+/** A name resolution in progress */
+struct resolution {
+	/** Asynchronous operation */
+	struct async async;
+	/** Numner of active child resolvers */
+	unsigned int pending;
+};
+
+/** Register as a name resolver */
+#define __resolver __table ( struct resolver, resolvers, 01 )
+
+extern int resolv ( const char *name, struct sockaddr *sa,
+		    struct async *parent );
+
+#endif /* _GPXE_RESOLV_H */

src/include/resolv.h

@@ -1,16 +0,0 @@
-#ifndef RESOLV_H
-#define RESOLV_H
-
-#include <gpxe/in.h>
-#include <gpxe/tables.h>
-
-struct resolver {
-	const char *name;
-	int ( * resolv ) ( struct in_addr *address, const char *name );
-};
-
-#define __resolver __table ( struct resolver, resolver, 01 )
-
-extern int resolv ( struct in_addr *address, const char *name );
-
-#endif /* RESOLV_H */

src/net/tcp/http.c

@@ -35,6 +35,7 @@
 #include <gpxe/uri.h>
 #include <gpxe/buffer.h>
 #include <gpxe/download.h>
+#include <gpxe/resolv.h>
 #include <gpxe/http.h>
 
 static struct async_operations http_async_operations;
@@ -391,17 +392,12 @@ int http_get ( struct uri *uri, struct buffer *buffer, struct async *parent ) {
 	http->buffer = buffer;
 	async_init ( &http->async, &http_async_operations, parent );
 
-
-#warning "Quick name resolution hack"
-	extern int dns_resolv ( const char *name,
-				struct sockaddr *sa,
-				struct async *parent );
-		
-	if ( ( rc = dns_resolv ( uri->host, &http->server,
-				 &http->async ) ) != 0 )
+	/* Start name resolution.  The download proper will start when
+	 * name resolution completes.
+	 */
+	if ( ( rc = resolv ( uri->host, &http->server, &http->async ) ) != 0 )
 		goto err;
 
-
 	return 0;
 
  err:

src/net/udp/dns.c

@@ -26,6 +26,7 @@
 #include <byteswap.h>
 #include <gpxe/async.h>
 #include <gpxe/udp.h>
+#include <gpxe/resolv.h>
 #include <gpxe/dns.h>
 
 /** @file
@@ -468,3 +469,9 @@ int dns_resolv ( const char *name, struct sockaddr *sa,
 	free ( dns );
 	return rc;
 }
+
+/** DNS name resolver */
+struct resolver dns_resolver __resolver = {
+	.name = "DNS",
+	.resolv = dns_resolv,
+};

src/usr/dhcpmgmt.c

@@ -24,6 +24,7 @@
 #include <gpxe/dhcp.h>
 #include <gpxe/async.h>
 #include <gpxe/netdevice.h>
+#include <gpxe/dns.h>
 #include <usr/ifmgmt.h>
 #include <usr/dhcpmgmt.h>
 
@@ -33,6 +34,9 @@
  *
  */
 
+/* Avoid dragging in dns.o */
+struct in_addr nameserver;
+
 /**
  * Configure network device via DHCP
  *
@@ -42,8 +46,8 @@
 int dhcp ( struct net_device *netdev ) {
 	static struct dhcp_option_block *dhcp_options = NULL;
 	struct dhcp_session dhcp;
-	struct in_addr address = { htonl ( 0 ) };
-	struct in_addr netmask = { htonl ( 0 ) };
+	struct in_addr address = { 0 };
+	struct in_addr netmask = { 0 };
 	struct in_addr gateway = { INADDR_NONE };
 	struct async async;
 	int rc;
@@ -90,5 +94,9 @@ int dhcp ( struct net_device *netdev ) {
 		return rc;
 	}
 
+	/* Retrieve other DHCP options that we care about */
+	find_dhcp_ipv4_option ( dhcp_options, DHCP_DNS_SERVERS,
+				&nameserver );
+
 	return 0;
 }