[dhcpv6] Add basic support for stateful and stateless DHCPv6

Add support for the stateful and stateless variants of the DHCPv6
protocol.  The resulting settings block is registered as
"net<x>.dhcpv6", and DHCPv6 options can be obtained using
e.g. "${net0.dhcpv6/23:ipv6}" to obtain the IPv6 DNS server address.

IPv6 addresses obtained via stateful DHCPv6 are not yet applied to the
network device.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/include/ipxe/dhcpv6.h

@@ -0,0 +1,215 @@
+#ifndef _IPXE_DHCPV6_H
+#define _IPXE_DHCPV6_H
+
+/** @file
+ *
+ * Dynamic Host Configuration Protocol for IPv6
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <stdint.h>
+#include <ipxe/in.h>
+
+/** DHCPv6 server port */
+#define DHCPV6_SERVER_PORT 547
+
+/** DHCPv6 client port */
+#define DHCPV6_CLIENT_PORT 546
+
+/**
+ * A DHCPv6 option
+ *
+ */
+struct dhcpv6_option {
+	/** Code */
+	uint16_t code;
+	/** Length of the data field */
+	uint16_t len;
+	/** Data */
+	uint8_t data[0];
+} __attribute__ (( packed ));
+
+/** DHCP unique identifier based on link-layer address (DUID-LL) */
+struct dhcpv6_duid_ll {
+	/** Type */
+	uint16_t type;
+	/** Hardware type */
+	uint16_t htype;
+	/** Link-layer address */
+	uint8_t ll_addr[0];
+} __attribute__ (( packed ));
+
+/** DHCP unique identifier based on link-layer address (DUID-LL) */
+#define DHCPV6_DUID_LL 3
+
+/** DHCPv6 client or server identifier option */
+struct dhcpv6_duid_option {
+	/** Option header */
+	struct dhcpv6_option header;
+	/** DHCP unique identifier (DUID) */
+	uint8_t duid[0];
+} __attribute__ (( packed ));
+
+/** DHCPv6 client identifier option */
+#define DHCPV6_CLIENT_ID 1
+
+/** DHCPv6 server identifier option */
+#define DHCPV6_SERVER_ID 2
+
+/** DHCPv6 identity association for non-temporary address (IA_NA) option */
+struct dhcpv6_ia_na_option {
+	/** Option header */
+	struct dhcpv6_option header;
+	/** Identity association identifier (IAID) */
+	uint32_t iaid;
+	/** Renew time (in seconds) */
+	uint32_t renew;
+	/** Rebind time (in seconds) */
+	uint32_t rebind;
+	/** IA_NA options */
+	struct dhcpv6_option options[0];
+} __attribute__ (( packed ));
+
+/** DHCPv6 identity association for non-temporary address (IA_NA) option */
+#define DHCPV6_IA_NA 3
+
+/** DHCPv6 identity association address (IAADDR) option */
+struct dhcpv6_iaaddr_option {
+	/** Option header */
+	struct dhcpv6_option header;
+	/** IPv6 address */
+	struct in6_addr address;
+	/** Preferred lifetime (in seconds) */
+	uint32_t preferred;
+	/** Valid lifetime (in seconds) */
+	uint32_t valid;
+	/** IAADDR options */
+	struct dhcpv6_option options[0];
+} __attribute__ (( packed ));
+
+/** DHCPv6 identity association address (IAADDR) option */
+#define DHCPV6_IAADDR 5
+
+/** DHCPv6 option request option */
+struct dhcpv6_option_request_option {
+	/** Option header */
+	struct dhcpv6_option header;
+	/** Requested options */
+	uint16_t requested[0];
+} __attribute__ (( packed ));
+
+/** DHCPv6 option request option */
+#define DHCPV6_OPTION_REQUEST 6
+
+/** DHCPv6 elapsed time option */
+struct dhcpv6_elapsed_time_option {
+	/** Option header */
+	struct dhcpv6_option header;
+	/** Elapsed time, in centiseconds */
+	uint16_t elapsed;
+} __attribute__ (( packed ));
+
+/** DHCPv6 elapsed time option */
+#define DHCPV6_ELAPSED_TIME 8
+
+/** DHCPv6 status code option */
+struct dhcpv6_status_code_option {
+	/** Option header */
+	struct dhcpv6_option header;
+	/** Status code */
+	uint16_t status;
+	/** Status message */
+	char message[0];
+} __attribute__ (( packed ));
+
+/** DHCPv6 status code option */
+#define DHCPV6_STATUS_CODE 13
+
+/** DHCPv6 user class */
+struct dhcpv6_user_class {
+	/** Length */
+	uint16_t len;
+	/** User class string */
+	char string[0];
+} __attribute__ (( packed ));
+
+/** DHCPv6 user class option */
+struct dhcpv6_user_class_option {
+	/** Option header */
+	struct dhcpv6_option header;
+	/** User class */
+	struct dhcpv6_user_class user_class[0];
+} __attribute__ (( packed ));
+
+/** DHCPv6 user class option */
+#define DHCPV6_USER_CLASS 15
+
+/** DHCPv6 DNS recursive name server option */
+#define DHCPV6_DNS_SERVER 23
+
+/** DHCPv6 domain search list option */
+#define DHCPV6_DOMAIN_SEARCH 24
+
+/**
+ * Any DHCPv6 option
+ *
+ */
+union dhcpv6_any_option {
+	struct dhcpv6_option header;
+	struct dhcpv6_duid_option duid;
+	struct dhcpv6_ia_na_option ia_na;
+	struct dhcpv6_iaaddr_option iaaddr;
+	struct dhcpv6_option_request_option option_request;
+	struct dhcpv6_elapsed_time_option elapsed_time;
+	struct dhcpv6_status_code_option status_code;
+	struct dhcpv6_user_class_option user_class;
+};
+
+/**
+ * A DHCPv6 header
+ *
+ */
+struct dhcpv6_header {
+	/** Message type */
+	uint8_t type;
+	/** Transaction ID */
+	uint8_t xid[3];
+	/** Options */
+	struct dhcpv6_option options[0];
+} __attribute__ (( packed ));
+
+/** DHCPv6 solicitation */
+#define DHCPV6_SOLICIT 1
+
+/** DHCPv6 advertisement */
+#define DHCPV6_ADVERTISE 2
+
+/** DHCPv6 request */
+#define DHCPV6_REQUEST 3
+
+/** DHCPv6 reply */
+#define DHCPV6_REPLY 7
+
+/** DHCPv6 information request */
+#define DHCPV6_INFORMATION_REQUEST 11
+
+/** DHCPv6 settings block name */
+#define DHCPV6_SETTINGS_NAME "dhcpv6"
+
+/**
+ * Construct all-DHCP-relay-agents-and-servers multicast address
+ *
+ * @v addr		Zeroed address to construct
+ */
+static inline void ipv6_all_dhcp_relay_and_servers ( struct in6_addr *addr ) {
+	addr->s6_addr16[0] = htons ( 0xff02 );
+	addr->s6_addr[13] = 1;
+	addr->s6_addr[15] = 2;
+}
+
+extern int start_dhcpv6 ( struct interface *job, struct net_device *netdev,
+			  int stateful );
+
+#endif /* _IPXE_DHCPV6_H */

src/include/ipxe/errfile.h

@@ -219,6 +219,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #define ERRFILE_socket			( ERRFILE_NET | 0x00380000 )
 #define ERRFILE_icmp			( ERRFILE_NET | 0x00390000 )
 #define ERRFILE_ping			( ERRFILE_NET | 0x003a0000 )
+#define ERRFILE_dhcpv6			( ERRFILE_NET | 0x003b0000 )
 
 #define ERRFILE_image		      ( ERRFILE_IMAGE | 0x00000000 )
 #define ERRFILE_elf		      ( ERRFILE_IMAGE | 0x00010000 )

src/net/ndp.c

@@ -29,6 +29,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #include <ipxe/ipv6.h>
 #include <ipxe/icmpv6.h>
 #include <ipxe/neighbour.h>
+#include <ipxe/dhcpv6.h>
 #include <ipxe/ndp.h>
 
 /** @file
@@ -596,6 +597,8 @@ struct ipv6conf {
 
 	/** Job control interface */
 	struct interface job;
+	/** DHCPv6 interface */
+	struct interface dhcp;
 
 	/** Network device being configured */
 	struct net_device *netdev;
@@ -646,6 +649,7 @@ static void ipv6conf_done ( struct ipv6conf *ipv6conf, int rc ) {
 
 	/* Shut down interfaces */
 	intf_shutdown ( &ipv6conf->job, rc );
+	intf_shutdown ( &ipv6conf->dhcp, rc );
 
 	/* Stop timer */
 	stop_timer ( &ipv6conf->timer );
@@ -686,6 +690,8 @@ static void ipv6conf_expired ( struct retry_timer *timer, int fail ) {
 static int ipv6conf_rx_router_advertisement ( struct net_device *netdev,
 					      unsigned int flags ) {
 	struct ipv6conf *ipv6conf;
+	int stateful;
+	int rc;
 
 	/* Identify IPv6 configurator, if any */
 	ipv6conf = ipv6conf_demux ( netdev );
@@ -697,13 +703,28 @@ static int ipv6conf_rx_router_advertisement ( struct net_device *netdev,
 		return 0;
 	}
 
-	/* Fail if stateful address autoconfiguration is required */
-	if ( flags & NDP_ROUTER_MANAGED ) {
-		ipv6conf_done ( ipv6conf, -ENOTSUP );
-		return -ENOTSUP;
+	/* If this is not the first solicited router advertisement, ignore it */
+	if ( ! timer_running ( &ipv6conf->timer ) )
+		return 0;
+
+	/* Stop router solicitation timer */
+	stop_timer ( &ipv6conf->timer );
+
+	/* Start DHCPv6 if required */
+	if ( flags & ( NDP_ROUTER_MANAGED | NDP_ROUTER_OTHER ) ) {
+		stateful = ( flags & NDP_ROUTER_MANAGED );
+		if ( ( rc = start_dhcpv6 ( &ipv6conf->dhcp, netdev,
+					   stateful ) ) != 0 ) {
+			DBGC ( netdev, "NDP could not start state%s DHCPv6: "
+			       "%s\n", ( stateful ? "ful" : "less" ),
+			       strerror ( rc ) );
+			ipv6conf_done ( ipv6conf, rc );
+			return rc;
+		}
+		return 0;
 	}
 
-	/* Mark autoconfiguration as complete */
+	/* Otherwise, terminate autoconfiguration */
 	ipv6conf_done ( ipv6conf, 0 );
 
 	return 0;
@@ -718,6 +739,15 @@ static struct interface_operation ipv6conf_job_op[] = {
 static struct interface_descriptor ipv6conf_job_desc =
 	INTF_DESC ( struct ipv6conf, job, ipv6conf_job_op );
 
+/** IPv6 configurator DHCPv6 interface operations */
+static struct interface_operation ipv6conf_dhcp_op[] = {
+	INTF_OP ( intf_close, struct ipv6conf *, ipv6conf_done ),
+};
+
+/** IPv6 configurator DHCPv6 interface descriptor */
+static struct interface_descriptor ipv6conf_dhcp_desc =
+	INTF_DESC ( struct ipv6conf, dhcp, ipv6conf_dhcp_op );
+
 /**
  * Start IPv6 autoconfiguration
  *
@@ -734,6 +764,7 @@ int start_ipv6conf ( struct interface *job, struct net_device *netdev ) {
 		return -ENOMEM;
 	ref_init ( &ipv6conf->refcnt, ipv6conf_free );
 	intf_init ( &ipv6conf->job, &ipv6conf_job_desc, &ipv6conf->refcnt );
+	intf_init ( &ipv6conf->dhcp, &ipv6conf_dhcp_desc, &ipv6conf->refcnt );
 	timer_init ( &ipv6conf->timer, ipv6conf_expired, &ipv6conf->refcnt );
 	ipv6conf->netdev = netdev_get ( netdev );
 

src/net/udp/dhcpv6.c

@@ -0,0 +1,955 @@
+/*
+ * Copyright (C) 2013 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., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <byteswap.h>
+#include <ipxe/interface.h>
+#include <ipxe/xfer.h>
+#include <ipxe/iobuf.h>
+#include <ipxe/open.h>
+#include <ipxe/netdevice.h>
+#include <ipxe/settings.h>
+#include <ipxe/retry.h>
+#include <ipxe/timer.h>
+#include <ipxe/in.h>
+#include <ipxe/crc32.h>
+#include <ipxe/errortab.h>
+#include <ipxe/dhcpv6.h>
+
+/** @file
+ *
+ * Dynamic Host Configuration Protocol for IPv6
+ *
+ */
+
+/* Disambiguate the various error causes */
+#define EPROTO_UNSPECFAIL __einfo_error ( EINFO_EPROTO_UNSPECFAIL )
+#define EINFO_EPROTO_UNSPECFAIL \
+	__einfo_uniqify ( EINFO_EPROTO, 1, "Unspecified server failure" )
+#define EPROTO_NOADDRSAVAIL __einfo_error ( EINFO_EPROTO_NOADDRSAVAIL )
+#define EINFO_EPROTO_NOADDRSAVAIL \
+	__einfo_uniqify ( EINFO_EPROTO, 2, "No addresses available" )
+#define EPROTO_NOBINDING __einfo_error ( EINFO_EPROTO_NOBINDING )
+#define EINFO_EPROTO_NOBINDING \
+	__einfo_uniqify ( EINFO_EPROTO, 3, "Client record unavailable" )
+#define EPROTO_NOTONLINK __einfo_error ( EINFO_EPROTO_NOTONLINK )
+#define EINFO_EPROTO_NOTONLINK \
+	__einfo_uniqify ( EINFO_EPROTO, 4, "Prefix not on link" )
+#define EPROTO_USEMULTICAST __einfo_error ( EINFO_EPROTO_USEMULTICAST )
+#define EINFO_EPROTO_USEMULTICAST \
+	__einfo_uniqify ( EINFO_EPROTO, 5, "Use multicast address" )
+#define EPROTO_STATUS( status )						\
+	EUNIQ ( EINFO_EPROTO, ( (status) & 0x0f ), EPROTO_UNSPECFAIL,	\
+		EPROTO_NOADDRSAVAIL, EPROTO_NOBINDING,			\
+		EPROTO_NOTONLINK, EPROTO_USEMULTICAST )
+
+/** Human-readable error messages */
+struct errortab dhcpv6_errors[] __errortab = {
+	__einfo_errortab ( EINFO_EPROTO_NOADDRSAVAIL ),
+};
+
+/****************************************************************************
+ *
+ * DHCPv6 option lists
+ *
+ */
+
+/** A DHCPv6 option list */
+struct dhcpv6_option_list {
+	/** Data buffer */
+	const void *data;
+	/** Length of data buffer */
+	size_t len;
+};
+
+/**
+ * Find DHCPv6 option
+ *
+ * @v options		DHCPv6 option list
+ * @v code		Option code
+ * @ret option		DHCPv6 option, or NULL if not found
+ */
+static const union dhcpv6_any_option *
+dhcpv6_option ( struct dhcpv6_option_list *options, unsigned int code ) {
+	const union dhcpv6_any_option *option = options->data;
+	size_t remaining = options->len;
+	size_t data_len;
+
+	/* Scan through list of options */
+	while ( remaining >= sizeof ( option->header ) ) {
+
+		/* Calculate and validate option length */
+		remaining -= sizeof ( option->header );
+		data_len = ntohs ( option->header.len );
+		if ( data_len > remaining ) {
+			/* Malformed option list */
+			return NULL;
+		}
+
+		/* Return if we have found the specified option */
+		if ( option->header.code == htons ( code ) )
+			return option;
+
+		/* Otherwise, move to the next option */
+		option = ( ( ( void * ) option->header.data ) + data_len );
+		remaining -= data_len;
+	}
+
+	return NULL;
+}
+
+/**
+ * Check DHCPv6 client or server identifier
+ *
+ * @v options		DHCPv6 option list
+ * @v code		Option code
+ * @v expected		Expected value
+ * @v len		Length of expected value
+ * @ret rc		Return status code
+ */
+static int dhcpv6_check_duid ( struct dhcpv6_option_list *options,
+			       unsigned int code, const void *expected,
+			       size_t len ) {
+	const union dhcpv6_any_option *option;
+	const struct dhcpv6_duid_option *duid;
+
+	/* Find option */
+	option = dhcpv6_option ( options, code );
+	if ( ! option )
+		return -ENOENT;
+	duid = &option->duid;
+
+	/* Check option length */
+	if ( ntohs ( duid->header.len ) != len )
+		return -EINVAL;
+
+	/* Compare option value */
+	if ( memcmp ( duid->duid, expected, len ) != 0 )
+		return -EINVAL;
+
+	return 0;
+}
+
+/**
+ * Get DHCPv6 status code
+ *
+ * @v options		DHCPv6 option list
+ * @ret rc		Return status code
+ */
+static int dhcpv6_status_code ( struct dhcpv6_option_list *options ) {
+	const union dhcpv6_any_option *option;
+	const struct dhcpv6_status_code_option *status_code;
+	unsigned int status;
+
+	/* Find status code option, if present */
+	option = dhcpv6_option ( options, DHCPV6_STATUS_CODE );
+	if ( ! option ) {
+		/* Omitted status code should be treated as "success" */
+		return 0;
+	}
+	status_code = &option->status_code;
+
+	/* Sanity check */
+	if ( ntohs ( status_code->header.len ) <
+	     ( sizeof ( *status_code ) - sizeof ( status_code->header ) ) ) {
+		return -EINVAL;
+	}
+
+	/* Calculate iPXE error code from DHCPv6 status code */
+	status = ntohs ( status_code->status );
+	return ( status ? -EPROTO_STATUS ( status ) : 0 );
+}
+
+/**
+ * Get DHCPv6 identity association address
+ *
+ * @v options		DHCPv6 option list
+ * @v iaid		Identity association ID
+ * @v address		IPv6 address to fill in
+ * @ret rc		Return status code
+ */
+static int dhcpv6_iaaddr ( struct dhcpv6_option_list *options, uint32_t iaid,
+			   struct in6_addr *address ) {
+	const union dhcpv6_any_option *option;
+	const struct dhcpv6_ia_na_option *ia_na;
+	const struct dhcpv6_iaaddr_option *iaaddr;
+	struct dhcpv6_option_list suboptions;
+	size_t len;
+	int rc;
+
+	/* Find identity association option, if present */
+	option = dhcpv6_option ( options, DHCPV6_IA_NA );
+	if ( ! option )
+		return -ENOENT;
+	ia_na = &option->ia_na;
+
+	/* Sanity check */
+	len = ntohs ( ia_na->header.len );
+	if ( len < ( sizeof ( *ia_na ) - sizeof ( ia_na->header ) ) )
+		return -EINVAL;
+
+	/* Check identity association ID */
+	if ( ia_na->iaid != htonl ( iaid ) )
+		return -EINVAL;
+
+	/* Construct IA_NA sub-options list */
+	suboptions.data = ia_na->options;
+	suboptions.len = ( len + sizeof ( ia_na->header ) -
+			   offsetof ( typeof ( *ia_na ), options ) );
+
+	/* Check IA_NA status code */
+	if ( ( rc = dhcpv6_status_code ( &suboptions ) ) != 0 )
+		return rc;
+
+	/* Find identity association address, if present */
+	option = dhcpv6_option ( &suboptions, DHCPV6_IAADDR );
+	if ( ! option )
+		return -ENOENT;
+	iaaddr = &option->iaaddr;
+
+	/* Sanity check */
+	len = ntohs ( iaaddr->header.len );
+	if ( len < ( sizeof ( *iaaddr ) - sizeof ( iaaddr->header ) ) )
+		return -EINVAL;
+
+	/* Construct IAADDR sub-options list */
+	suboptions.data = iaaddr->options;
+	suboptions.len = ( len + sizeof ( iaaddr->header ) -
+			   offsetof ( typeof ( *iaaddr ), options ) );
+
+	/* Check IAADDR status code */
+	if ( ( rc = dhcpv6_status_code ( &suboptions ) ) != 0 )
+		return rc;
+
+	/* Extract IPv6 address */
+	memcpy ( address, &iaaddr->address, sizeof ( *address ) );
+
+	return 0;
+}
+
+/****************************************************************************
+ *
+ * DHCPv6 settings blocks
+ *
+ */
+
+/** DHCPv6 settings scope */
+static struct settings_scope dhcpv6_settings_scope;
+
+/** A DHCPv6 settings block */
+struct dhcpv6_settings {
+	/** Reference count */
+	struct refcnt refcnt;
+	/** Settings block */
+	struct settings settings;
+	/** Option list */
+	struct dhcpv6_option_list options;
+};
+
+/**
+ * Check applicability of DHCPv6 setting
+ *
+ * @v settings		Settings block
+ * @v setting		Setting
+ * @ret applies		Setting applies within this settings block
+ */
+static int dhcpv6_applies ( struct settings *settings __unused,
+			    struct setting *setting ) {
+
+	return ( setting->scope == &dhcpv6_settings_scope );
+}
+
+/**
+ * Fetch value of DHCPv6 setting
+ *
+ * @v settings		Settings block
+ * @v setting		Setting to fetch
+ * @v data		Buffer to fill with setting data
+ * @v len		Length of buffer
+ * @ret len		Length of setting data, or negative error
+ */
+static int dhcpv6_fetch ( struct settings *settings,
+			  struct setting *setting,
+			  void *data, size_t len ) {
+	struct dhcpv6_settings *dhcpv6set =
+		container_of ( settings, struct dhcpv6_settings, settings );
+	const union dhcpv6_any_option *option;
+	size_t option_len;
+
+	/* Find option */
+	option = dhcpv6_option ( &dhcpv6set->options, setting->tag );
+	if ( ! option )
+		return -ENOENT;
+
+	/* Copy option to data buffer */
+	option_len = ntohs ( option->header.len );
+	if ( len > option_len )
+		len = option_len;
+	memcpy ( data, option->header.data, len );
+	return option_len;
+}
+
+/** DHCPv6 settings operations */
+static struct settings_operations dhcpv6_settings_operations = {
+	.applies = dhcpv6_applies,
+	.fetch = dhcpv6_fetch,
+};
+
+/**
+ * Register DHCPv6 options as network device settings
+ *
+ * @v options		DHCPv6 option list
+ * @v parent		Parent settings block
+ * @ret rc		Return status code
+ */
+static int dhcpv6_register ( struct dhcpv6_option_list *options,
+			     struct settings *parent ) {
+	struct dhcpv6_settings *dhcpv6set;
+	void *data;
+	size_t len;
+	int rc;
+
+	/* Allocate and initialise structure */
+	dhcpv6set = zalloc ( sizeof ( *dhcpv6set ) + options->len );
+	if ( ! dhcpv6set ) {
+		rc = -ENOMEM;
+		goto err_alloc;
+	}
+	ref_init ( &dhcpv6set->refcnt, NULL );
+	settings_init ( &dhcpv6set->settings, &dhcpv6_settings_operations,
+			&dhcpv6set->refcnt, &dhcpv6_settings_scope );
+	data = ( ( ( void * ) dhcpv6set ) + sizeof ( *dhcpv6set ) );
+	len = options->len;
+	memcpy ( data, options->data, len );
+	dhcpv6set->options.data = data;
+	dhcpv6set->options.len = len;
+
+	/* Register settings */
+	if ( ( rc = register_settings ( &dhcpv6set->settings, parent,
+					DHCPV6_SETTINGS_NAME ) ) != 0 )
+		goto err_register;
+
+ err_register:
+	ref_put ( &dhcpv6set->refcnt );
+ err_alloc:
+	return rc;
+}
+
+/****************************************************************************
+ *
+ * DHCPv6 protocol
+ *
+ */
+
+/** Options to be requested */
+static uint16_t dhcpv6_requested_options[] = {
+	htons ( DHCPV6_DNS_SERVER ), htons ( DHCPV6_DOMAIN_SEARCH ),
+};
+
+/**
+ * Name a DHCPv6 packet type
+ *
+ * @v type		DHCPv6 packet type
+ * @ret name		DHCPv6 packet type name
+ */
+static __attribute__ (( unused )) const char *
+dhcpv6_type_name ( unsigned int type ) {
+	static char buf[ 12 /* "UNKNOWN-xxx" + NUL */ ];
+
+	switch ( type ) {
+	case DHCPV6_SOLICIT:			return "SOLICIT";
+	case DHCPV6_ADVERTISE:			return "ADVERTISE";
+	case DHCPV6_REQUEST:			return "REQUEST";
+	case DHCPV6_REPLY:			return "REPLY";
+	case DHCPV6_INFORMATION_REQUEST:	return "INFORMATION-REQUEST";
+	default:
+		snprintf ( buf, sizeof ( buf ), "UNKNOWN-%d", type );
+		return buf;
+	}
+}
+
+/** A DHCPv6 session state */
+struct dhcpv6_session_state {
+	/** Current transmitted packet type */
+	uint8_t tx_type;
+	/** Current expected received packet type */
+	uint8_t rx_type;
+	/** Flags */
+	uint8_t flags;
+	/** Next state (or NULL to terminate) */
+	struct dhcpv6_session_state *next;
+};
+
+/** DHCPv6 session state flags */
+enum dhcpv6_session_state_flags {
+	/** Include identity association within request */
+	DHCPV6_TX_IA_NA = 0x01,
+	/** Include leased IPv6 address within request */
+	DHCPV6_TX_IAADDR = 0x02,
+	/** Record received server ID */
+	DHCPV6_RX_SERVER_ID = 0x04,
+	/** Record received IPv6 address */
+	DHCPV6_RX_IAADDR = 0x08,
+};
+
+/** DHCPv6 request state */
+static struct dhcpv6_session_state dhcpv6_request = {
+	.tx_type = DHCPV6_REQUEST,
+	.rx_type = DHCPV6_REPLY,
+	.flags = ( DHCPV6_TX_IA_NA | DHCPV6_TX_IAADDR | DHCPV6_RX_IAADDR ),
+	.next = NULL,
+};
+
+/** DHCPv6 solicitation state */
+static struct dhcpv6_session_state dhcpv6_solicit = {
+	.tx_type = DHCPV6_SOLICIT,
+	.rx_type = DHCPV6_ADVERTISE,
+	.flags = ( DHCPV6_TX_IA_NA | DHCPV6_RX_SERVER_ID | DHCPV6_RX_IAADDR ),
+	.next = &dhcpv6_request,
+};
+
+/** DHCPv6 information request state */
+static struct dhcpv6_session_state dhcpv6_information_request = {
+	.tx_type = DHCPV6_INFORMATION_REQUEST,
+	.rx_type = DHCPV6_REPLY,
+	.flags = 0,
+	.next = NULL,
+};
+
+/** A DHCPv6 session */
+struct dhcpv6_session {
+	/** Reference counter */
+	struct refcnt refcnt;
+	/** Job control interface */
+	struct interface job;
+	/** Data transfer interface */
+	struct interface xfer;
+
+	/** Network device being configured */
+	struct net_device *netdev;
+	/** Transaction ID */
+	uint8_t xid[3];
+	/** Identity association ID */
+	uint32_t iaid;
+	/** Start time (in ticks) */
+	unsigned long start;
+	/** Client DUID */
+	void *client_duid;
+	/** Client DUID length */
+	size_t client_duid_len;
+	/** Server DUID, if known */
+	void *server_duid;
+	/** Server DUID length */
+	size_t server_duid_len;
+	/** Leased IPv6 address */
+	struct in6_addr lease;
+
+	/** Retransmission timer */
+	struct retry_timer timer;
+
+	/** Current session state */
+	struct dhcpv6_session_state *state;
+	/** Current timeout status code */
+	int rc;
+};
+
+/**
+ * Free DHCPv6 session
+ *
+ * @v refcnt		Reference count
+ */
+static void dhcpv6_free ( struct refcnt *refcnt ) {
+	struct dhcpv6_session *dhcpv6 =
+		container_of ( refcnt, struct dhcpv6_session, refcnt );
+
+	netdev_put ( dhcpv6->netdev );
+	free ( dhcpv6->server_duid );
+	free ( dhcpv6 );
+}
+
+/**
+ * Terminate DHCPv6 session
+ *
+ * @v dhcpv6		DHCPv6 session
+ * @v rc		Reason for close
+ */
+static void dhcpv6_finished ( struct dhcpv6_session *dhcpv6, int rc ) {
+
+	/* Stop timer */
+	stop_timer ( &dhcpv6->timer );
+
+	/* Shut down interfaces */
+	intf_shutdown ( &dhcpv6->xfer, rc );
+	intf_shutdown ( &dhcpv6->job, rc );
+}
+
+/**
+ * Transition to new DHCPv6 session state
+ *
+ * @v dhcpv6		DHCPv6 session
+ * @v state		New session state
+ */
+static void dhcpv6_set_state ( struct dhcpv6_session *dhcpv6,
+			       struct dhcpv6_session_state *state ) {
+
+	DBGC ( dhcpv6, "DHCPv6 %s entering %s state\n", dhcpv6->netdev->name,
+	       dhcpv6_type_name ( state->tx_type ) );
+
+	/* Record state */
+	dhcpv6->state = state;
+
+	/* Default to -ETIMEDOUT if no more specific error is recorded */
+	dhcpv6->rc = -ETIMEDOUT;
+
+	/* Start timer to trigger transmission */
+	start_timer_nodelay ( &dhcpv6->timer );
+}
+
+/**
+ * Get DHCPv6 user class
+ *
+ * @v data		Data buffer
+ * @v len		Length of data buffer
+ * @ret len		Length of user class
+ */
+static size_t dhcpv6_user_class ( void *data, size_t len ) {
+	static const char default_user_class[4] = { 'i', 'P', 'X', 'E' };
+	int actual_len;
+
+	/* Fetch user-class setting, if defined */
+	actual_len = fetch_setting ( NULL, &user_class_setting, data, len );
+	if ( actual_len >= 0 )
+		return actual_len;
+
+	/* Otherwise, use the default user class ("iPXE") */
+	if ( len > sizeof ( default_user_class ) )
+		len = sizeof ( default_user_class );
+	memcpy ( data, default_user_class, len );
+	return sizeof ( default_user_class );
+}
+
+/**
+ * Transmit current request
+ *
+ * @v dhcpv6		DHCPv6 session
+ * @ret rc		Return status code
+ */
+static int dhcpv6_tx ( struct dhcpv6_session *dhcpv6 ) {
+	struct dhcpv6_duid_option *client_id;
+	struct dhcpv6_duid_option *server_id;
+	struct dhcpv6_ia_na_option *ia_na;
+	struct dhcpv6_iaaddr_option *iaaddr;
+	struct dhcpv6_option_request_option *option_request;
+	struct dhcpv6_user_class_option *user_class;
+	struct dhcpv6_elapsed_time_option *elapsed;
+	struct dhcpv6_header *dhcphdr;
+	struct io_buffer *iobuf;
+	size_t client_id_len;
+	size_t server_id_len;
+	size_t ia_na_len;
+	size_t option_request_len;
+	size_t user_class_string_len;
+	size_t user_class_len;
+	size_t elapsed_len;
+	size_t total_len;
+	int rc;
+
+	/* Calculate lengths */
+	client_id_len = ( sizeof ( *client_id ) + dhcpv6->client_duid_len );
+	server_id_len = ( dhcpv6->server_duid ? ( sizeof ( *server_id ) +
+						  dhcpv6->server_duid_len ) :0);
+	if ( dhcpv6->state->flags & DHCPV6_TX_IA_NA ) {
+		ia_na_len = sizeof ( *ia_na );
+		if ( dhcpv6->state->flags & DHCPV6_TX_IAADDR )
+			ia_na_len += sizeof ( *iaaddr );
+	} else {
+		ia_na_len = 0;
+	}
+	option_request_len = ( sizeof ( *option_request ) +
+			       sizeof ( dhcpv6_requested_options ) );
+	user_class_string_len = dhcpv6_user_class ( NULL, 0 );
+	user_class_len = ( sizeof ( *user_class ) +
+			   sizeof ( user_class->user_class[0] ) +
+			   user_class_string_len );
+	elapsed_len = sizeof ( *elapsed );
+	total_len = ( sizeof ( *dhcphdr ) + client_id_len + server_id_len +
+		      ia_na_len + option_request_len + user_class_len +
+		      elapsed_len );
+
+	/* Allocate packet */
+	iobuf = xfer_alloc_iob ( &dhcpv6->xfer, total_len );
+	if ( ! iobuf )
+		return -ENOMEM;
+
+	/* Construct header */
+	dhcphdr = iob_put ( iobuf, sizeof ( *dhcphdr ) );
+	dhcphdr->type = dhcpv6->state->tx_type;
+	memcpy ( dhcphdr->xid, dhcpv6->xid, sizeof ( dhcphdr->xid ) );
+
+	/* Construct client identifier */
+	client_id = iob_put ( iobuf, client_id_len );
+	client_id->header.code = htons ( DHCPV6_CLIENT_ID );
+	client_id->header.len = htons ( client_id_len -
+					sizeof ( client_id->header ) );
+	memcpy ( client_id->duid, dhcpv6->client_duid,
+		 dhcpv6->client_duid_len );
+
+	/* Construct server identifier, if applicable */
+	if ( server_id_len ) {
+		server_id = iob_put ( iobuf, server_id_len );
+		server_id->header.code = htons ( DHCPV6_SERVER_ID );
+		server_id->header.len = htons ( server_id_len -
+						sizeof ( server_id->header ) );
+		memcpy ( server_id->duid, dhcpv6->server_duid,
+			 dhcpv6->server_duid_len );
+	}
+
+	/* Construct identity association, if applicable */
+	if ( ia_na_len ) {
+		ia_na = iob_put ( iobuf, ia_na_len );
+		ia_na->header.code = htons ( DHCPV6_IA_NA );
+		ia_na->header.len = htons ( ia_na_len -
+					    sizeof ( ia_na->header ) );
+		ia_na->iaid = htonl ( dhcpv6->iaid );
+		ia_na->renew = htonl ( 0 );
+		ia_na->rebind = htonl ( 0 );
+		if ( dhcpv6->state->flags & DHCPV6_TX_IAADDR ) {
+			iaaddr = ( ( void * ) ia_na->options );
+			iaaddr->header.code = htons ( DHCPV6_IAADDR );
+			iaaddr->header.len = htons ( sizeof ( *iaaddr ) -
+						     sizeof ( iaaddr->header ));
+			memcpy ( &iaaddr->address, &dhcpv6->lease,
+				 sizeof ( iaaddr->address ) );
+			iaaddr->preferred = htonl ( 0 );
+			iaaddr->valid = htonl ( 0 );
+		}
+	}
+
+	/* Construct option request */
+	option_request = iob_put ( iobuf, option_request_len );
+	option_request->header.code = htons ( DHCPV6_OPTION_REQUEST );
+	option_request->header.len = htons ( option_request_len -
+					     sizeof ( option_request->header ));
+	memcpy ( option_request->requested, dhcpv6_requested_options,
+		 sizeof ( dhcpv6_requested_options ) );
+
+	/* Construct user class */
+	user_class = iob_put ( iobuf, user_class_len );
+	user_class->header.code = htons ( DHCPV6_USER_CLASS );
+	user_class->header.len = htons ( user_class_len -
+					 sizeof ( user_class->header ) );
+	user_class->user_class[0].len = htons ( user_class_string_len );
+	dhcpv6_user_class ( user_class->user_class[0].string,
+			    user_class_string_len );
+
+	/* Construct elapsed time */
+	elapsed = iob_put ( iobuf, elapsed_len );
+	elapsed->header.code = htons ( DHCPV6_ELAPSED_TIME );
+	elapsed->header.len = htons ( elapsed_len -
+				      sizeof ( elapsed->header ) );
+	elapsed->elapsed = htons ( ( ( currticks() - dhcpv6->start ) * 100 ) /
+				   TICKS_PER_SEC );
+
+	/* Sanity check */
+	assert ( iob_len ( iobuf ) == total_len );
+
+	/* Transmit packet */
+	if ( ( rc = xfer_deliver_iob ( &dhcpv6->xfer, iobuf ) ) != 0 ) {
+		DBGC ( dhcpv6, "DHCPv6 %s could not transmit: %s\n",
+		       dhcpv6->netdev->name, strerror ( rc ) );
+		return rc;
+	}
+
+	return 0;
+}
+
+/**
+ * Handle timer expiry
+ *
+ * @v timer		Retransmission timer
+ * @v fail		Failure indicator
+ */
+static void dhcpv6_timer_expired ( struct retry_timer *timer, int fail ) {
+	struct dhcpv6_session *dhcpv6 =
+		container_of ( timer, struct dhcpv6_session, timer );
+
+	/* If we have failed, terminate DHCPv6 */
+	if ( fail ) {
+		dhcpv6_finished ( dhcpv6, dhcpv6->rc );
+		return;
+	}
+
+	/* Restart timer */
+	start_timer ( &dhcpv6->timer );
+
+	/* (Re)transmit current request */
+	dhcpv6_tx ( dhcpv6 );
+}
+
+/**
+ * Receive new data
+ *
+ * @v dhcpv6		DHCPv6 session
+ * @v iobuf		I/O buffer
+ * @v meta		Data transfer metadata
+ * @ret rc		Return status code
+ */
+static int dhcpv6_rx ( struct dhcpv6_session *dhcpv6,
+		       struct io_buffer *iobuf,
+		       struct xfer_metadata *meta ) {
+	struct settings *parent = netdev_settings ( dhcpv6->netdev );
+	struct sockaddr_in6 *src = ( ( struct sockaddr_in6 * ) meta->src );
+	struct dhcpv6_header *dhcphdr = iobuf->data;
+	struct dhcpv6_option_list options;
+	const union dhcpv6_any_option *option;
+	int rc;
+
+	/* Sanity checks */
+	if ( iob_len ( iobuf ) < sizeof ( *dhcphdr ) ) {
+		DBGC ( dhcpv6, "DHCPv6 %s received packet too short (%zd "
+		       "bytes, min %zd bytes)\n", dhcpv6->netdev->name,
+		       iob_len ( iobuf ), sizeof ( *dhcphdr ) );
+		rc = -EINVAL;
+		goto done;
+	}
+	assert ( src != NULL );
+	assert ( src->sin6_family == AF_INET6 );
+	DBGC ( dhcpv6, "DHCPv6 %s received %s from %s\n",
+	       dhcpv6->netdev->name, dhcpv6_type_name ( dhcphdr->type ),
+	       inet6_ntoa ( &src->sin6_addr ) );
+
+	/* Construct option list */
+	options.data = dhcphdr->options;
+	options.len = ( iob_len ( iobuf ) -
+			offsetof ( typeof ( *dhcphdr ), options ) );
+
+	/* Verify client identifier */
+	if ( ( rc = dhcpv6_check_duid ( &options, DHCPV6_CLIENT_ID,
+					dhcpv6->client_duid,
+					dhcpv6->client_duid_len ) ) != 0 ) {
+		DBGC ( dhcpv6, "DHCPv6 %s received %s without correct client "
+		       "ID: %s\n", dhcpv6->netdev->name,
+		       dhcpv6_type_name ( dhcphdr->type ), strerror ( rc ) );
+		goto done;
+	}
+
+	/* Verify server identifier, if applicable */
+	if ( dhcpv6->server_duid &&
+	     ( ( rc = dhcpv6_check_duid ( &options, DHCPV6_SERVER_ID,
+					  dhcpv6->server_duid,
+					  dhcpv6->server_duid_len ) ) != 0 ) ) {
+		DBGC ( dhcpv6, "DHCPv6 %s received %s without correct server "
+		       "ID: %s\n", dhcpv6->netdev->name,
+		       dhcpv6_type_name ( dhcphdr->type ), strerror ( rc ) );
+		goto done;
+	}
+
+	/* Check message type */
+	if ( dhcphdr->type != dhcpv6->state->rx_type ) {
+		DBGC ( dhcpv6, "DHCPv6 %s received %s while expecting %s\n",
+		       dhcpv6->netdev->name, dhcpv6_type_name ( dhcphdr->type ),
+		       dhcpv6_type_name ( dhcpv6->state->rx_type ) );
+		rc = -ENOTTY;
+		goto done;
+	}
+
+	/* Fetch status code, if present */
+	if ( ( rc = dhcpv6_status_code ( &options ) ) != 0 ) {
+		DBGC ( dhcpv6, "DHCPv6 %s received %s with error status: %s\n",
+		       dhcpv6->netdev->name, dhcpv6_type_name ( dhcphdr->type ),
+		       strerror ( rc ) );
+		/* This is plausibly the error we want to return */
+		dhcpv6->rc = rc;
+		goto done;
+	}
+
+	/* Record identity association address, if applicable */
+	if ( dhcpv6->state->flags & DHCPV6_RX_IAADDR ) {
+		if ( ( rc = dhcpv6_iaaddr ( &options, dhcpv6->iaid,
+					    &dhcpv6->lease ) ) != 0 ) {
+			DBGC ( dhcpv6, "DHCPv6 %s received %s with unusable "
+			       "IAADDR: %s\n", dhcpv6->netdev->name,
+			       dhcpv6_type_name ( dhcphdr->type ),
+			       strerror ( rc ) );
+			/* This is plausibly the error we want to return */
+			dhcpv6->rc = rc;
+			goto done;
+		}
+		DBGC ( dhcpv6, "DHCPv6 %s received %s is for %s\n",
+		       dhcpv6->netdev->name, dhcpv6_type_name ( dhcphdr->type ),
+		       inet6_ntoa ( &dhcpv6->lease ) );
+	}
+
+	/* Record server ID, if applicable */
+	if ( dhcpv6->state->flags & DHCPV6_RX_SERVER_ID ) {
+		assert ( dhcpv6->server_duid == NULL );
+		option = dhcpv6_option ( &options, DHCPV6_SERVER_ID );
+		if ( ! option ) {
+			DBGC ( dhcpv6, "DHCPv6 %s received %s missing server "
+			       "ID\n", dhcpv6->netdev->name,
+			       dhcpv6_type_name ( dhcphdr->type ) );
+			rc = -EINVAL;
+			goto done;
+		}
+		dhcpv6->server_duid_len = ntohs ( option->duid.header.len );
+		dhcpv6->server_duid = malloc ( dhcpv6->server_duid_len );
+		if ( ! dhcpv6->server_duid ) {
+			rc = -ENOMEM;
+			goto done;
+		}
+		memcpy ( dhcpv6->server_duid, option->duid.duid,
+			 dhcpv6->server_duid_len );
+	}
+
+	/* Transition to next state or complete DHCPv6, as applicable */
+	if ( dhcpv6->state->next ) {
+
+		/* Transition to next state */
+		dhcpv6_set_state ( dhcpv6, dhcpv6->state->next );
+		rc = 0;
+
+	} else {
+
+		/* Register settings */
+		if ( ( rc = dhcpv6_register ( &options, parent ) ) != 0 ) {
+			DBGC ( dhcpv6, "DHCPv6 %s could not register "
+			       "settings: %s\n", dhcpv6->netdev->name,
+			       strerror ( rc ) );
+			goto done;
+		}
+
+		/* Mark as complete */
+		dhcpv6_finished ( dhcpv6, 0 );
+		DBGC ( dhcpv6, "DHCPv6 %s complete\n", dhcpv6->netdev->name );
+	}
+
+ done:
+	free_iob ( iobuf );
+	return rc;
+}
+
+/** DHCPv6 job control interface operations */
+static struct interface_operation dhcpv6_job_op[] = {
+	INTF_OP ( intf_close, struct dhcpv6_session *, dhcpv6_finished ),
+};
+
+/** DHCPv6 job control interface descriptor */
+static struct interface_descriptor dhcpv6_job_desc =
+	INTF_DESC ( struct dhcpv6_session, job, dhcpv6_job_op );
+
+/** DHCPv6 data transfer interface operations */
+static struct interface_operation dhcpv6_xfer_op[] = {
+	INTF_OP ( xfer_deliver, struct dhcpv6_session *, dhcpv6_rx ),
+};
+
+/** DHCPv6 data transfer interface descriptor */
+static struct interface_descriptor dhcpv6_xfer_desc =
+	INTF_DESC ( struct dhcpv6_session, xfer, dhcpv6_xfer_op );
+
+/**
+ * Start DHCPv6
+ *
+ * @v job		Job control interface
+ * @v netdev		Network device
+ * @v stateful		Perform stateful address autoconfiguration
+ * @ret rc		Return status code
+ */
+int start_dhcpv6 ( struct interface *job, struct net_device *netdev,
+		   int stateful ) {
+	struct ll_protocol *ll_protocol = netdev->ll_protocol;
+	struct dhcpv6_session *dhcpv6;
+	struct {
+		union {
+			struct sockaddr_in6 sin6;
+			struct sockaddr sa;
+		} client;
+		union {
+			struct sockaddr_in6 sin6;
+			struct sockaddr sa;
+		} server;
+	} addresses;
+	struct dhcpv6_duid_ll *client_duid;
+	size_t client_duid_len;
+	uint32_t xid;
+	int rc;
+
+	/* Allocate and initialise structure */
+	client_duid_len = ( sizeof ( *client_duid ) + ll_protocol->ll_addr_len);
+	dhcpv6 = zalloc ( sizeof ( *dhcpv6 ) + client_duid_len );
+	if ( ! dhcpv6 )
+		return -ENOMEM;
+	ref_init ( &dhcpv6->refcnt, dhcpv6_free );
+	intf_init ( &dhcpv6->job, &dhcpv6_job_desc, &dhcpv6->refcnt );
+	intf_init ( &dhcpv6->xfer, &dhcpv6_xfer_desc, &dhcpv6->refcnt );
+	dhcpv6->netdev = netdev_get ( netdev );
+	xid = random();
+	memcpy ( dhcpv6->xid, &xid, sizeof ( dhcpv6->xid ) );
+	dhcpv6->start = currticks();
+	dhcpv6->client_duid = ( ( ( void * ) dhcpv6 ) + sizeof ( *dhcpv6 ) );
+	dhcpv6->client_duid_len = client_duid_len;
+	timer_init ( &dhcpv6->timer, dhcpv6_timer_expired, &dhcpv6->refcnt );
+
+	/* Construct client and server addresses */
+	memset ( &addresses, 0, sizeof ( addresses ) );
+	addresses.client.sin6.sin6_family = AF_INET6;
+	addresses.client.sin6.sin6_scope_id = netdev->index;
+	addresses.client.sin6.sin6_port = htons ( DHCPV6_CLIENT_PORT );
+	addresses.server.sin6.sin6_family = AF_INET6;
+	ipv6_all_dhcp_relay_and_servers ( &addresses.server.sin6.sin6_addr );
+	addresses.server.sin6.sin6_scope_id = netdev->index;
+	addresses.server.sin6.sin6_port = htons ( DHCPV6_SERVER_PORT );
+
+	/* Construct client DUID and IAID from link-layer address */
+	client_duid = dhcpv6->client_duid;
+	client_duid->type = htons ( DHCPV6_DUID_LL );
+	client_duid->htype = ll_protocol->ll_proto;
+	memcpy ( client_duid->ll_addr, netdev->ll_addr,
+		 ll_protocol->ll_addr_len );
+	dhcpv6->iaid = crc32_le ( 0, netdev->ll_addr, ll_protocol->ll_addr_len);
+	DBGC ( dhcpv6, "DHCPv6 %s has XID %02x%02x%02x\n", dhcpv6->netdev->name,
+	       dhcpv6->xid[0], dhcpv6->xid[1], dhcpv6->xid[2] );
+
+	/* Enter initial state */
+	dhcpv6_set_state ( dhcpv6, ( stateful ? &dhcpv6_solicit :
+				     &dhcpv6_information_request ) );
+
+	/* Open socket */
+	if ( ( rc = xfer_open_socket ( &dhcpv6->xfer, SOCK_DGRAM,
+				       &addresses.server.sa,
+				       &addresses.client.sa ) ) != 0 ) {
+		DBGC ( dhcpv6, "DHCPv6 %s could not open socket: %s\n",
+		       dhcpv6->netdev->name, strerror ( rc ) );
+		goto err_open_socket;
+	}
+
+	/* Attach parent interface, mortalise self, and return */
+	intf_plug_plug ( &dhcpv6->job, job );
+	ref_put ( &dhcpv6->refcnt );
+	return 0;
+
+ err_open_socket:
+	dhcpv6_finished ( dhcpv6, rc );
+	ref_put ( &dhcpv6->refcnt );
+	return rc;
+}