ipv6.c

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/*
 * 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 );
FILE_SECBOOT ( PERMITTED );

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <errno.h>
#include <assert.h>
#include <byteswap.h>
#include <ipxe/iobuf.h>
#include <ipxe/tcpip.h>
#include <ipxe/if_ether.h>
#include <ipxe/crc32.h>
#include <ipxe/fragment.h>
#include <ipxe/ipstat.h>
#include <ipxe/ndp.h>
#include <ipxe/ipv6.h>

/** @file
 *
 * IPv6 protocol
 *
 */

/* Disambiguate the various error causes */
#define EINVAL_LEN __einfo_error ( EINFO_EINVAL_LEN )
#define EINFO_EINVAL_LEN \
        __einfo_uniqify ( EINFO_EINVAL, 0x01, "Invalid length" )
#define ENOTSUP_VER __einfo_error ( EINFO_ENOTSUP_VER )
#define EINFO_ENOTSUP_VER \
        __einfo_uniqify ( EINFO_ENOTSUP, 0x01, "Unsupported version" )
#define ENOTSUP_HDR __einfo_error ( EINFO_ENOTSUP_HDR )
#define EINFO_ENOTSUP_HDR \
        __einfo_uniqify ( EINFO_ENOTSUP, 0x02, "Unsupported header type" )
#define ENOTSUP_OPT __einfo_error ( EINFO_ENOTSUP_OPT )
#define EINFO_ENOTSUP_OPT \
        __einfo_uniqify ( EINFO_ENOTSUP, 0x03, "Unsupported option" )

/** List of IPv6 miniroutes */
struct list_head ipv6_miniroutes = LIST_HEAD_INIT ( ipv6_miniroutes );

/** IPv6 statistics */
static struct ip_statistics ipv6_stats;

/** IPv6 statistics family */
struct ip_statistics_family
ipv6_statistics_family __ip_statistics_family ( IP_STATISTICS_IPV6 ) = {
        .version = 6,
        .stats = &ipv6_stats,
};

/**
 * Determine debugging colour for IPv6 debug messages
 *
 * @v in                IPv6 address
 * @ret col             Debugging colour (for DBGC())
 */
static uint32_t ipv6col ( struct in6_addr *in ) {
        return crc32_le ( 0, in, sizeof ( *in ) );
}

/**
 * Determine IPv6 address scope
 *
 * @v addr              IPv6 address
 * @ret scope           Address scope
 */
static unsigned int ipv6_scope ( const struct in6_addr *addr ) {

        /* Multicast addresses directly include a scope field */
        if ( IN6_IS_ADDR_MULTICAST ( addr ) )
                return ipv6_multicast_scope ( addr );

        /* Link-local addresses have link-local scope */
        if ( IN6_IS_ADDR_LINKLOCAL ( addr ) )
                return IPV6_SCOPE_LINK_LOCAL;

        /* Site-local addresses have site-local scope */
        if ( IN6_IS_ADDR_SITELOCAL ( addr ) )
                return IPV6_SCOPE_SITE_LOCAL;

        /* Unique local addresses do not directly map to a defined
         * scope.  They effectively have a scope which is wider than
         * link-local but narrower than global.  Since the only
         * multicast packets that we transmit are link-local, we can
         * simply choose an arbitrary scope between link-local and
         * global.
         */
        if ( IN6_IS_ADDR_ULA ( addr ) )
                return IPV6_SCOPE_ORGANISATION_LOCAL;

        /* All other addresses are assumed to be global */
        return IPV6_SCOPE_GLOBAL;
}

/**
 * Dump IPv6 routing table entry
 *
 * @v miniroute         Routing table entry
 */
static inline __attribute__ (( always_inline )) void
ipv6_dump_miniroute ( struct ipv6_miniroute *miniroute ) {
        struct net_device *netdev = miniroute->netdev;

        DBGC ( netdev, "IPv6 %s has %s %s/%d", netdev->name,
               ( ( miniroute->flags & IPV6_HAS_ADDRESS ) ?
                 "address" : "prefix" ),
               inet6_ntoa ( &miniroute->address ), miniroute->prefix_len );
        if ( miniroute->flags & IPV6_HAS_ROUTER )
                DBGC ( netdev, " router %s", inet6_ntoa ( &miniroute->router ));
        DBGC ( netdev, "\n" );
}

/**
 * Check if network device has a specific IPv6 address
 *
 * @v netdev            Network device
 * @v addr              IPv6 address
 * @ret has_addr        Network device has this IPv6 address
 */
int ipv6_has_addr ( struct net_device *netdev, struct in6_addr *addr ) {
        struct ipv6_miniroute *miniroute;

        list_for_each_entry ( miniroute, &ipv6_miniroutes, list ) {
                if ( ( miniroute->netdev == netdev ) &&
                     ( miniroute->flags & IPV6_HAS_ADDRESS ) &&
                     ( memcmp ( &miniroute->address, addr,
                                sizeof ( miniroute->address ) ) == 0 ) ) {
                        /* Found matching address */
                        return 1;
                }
        }
        return 0;
}

/**
 * Count matching bits of an IPv6 routing table entry prefix
 *
 * @v miniroute         Routing table entry
 * @v address           IPv6 address
 * @ret match_len       Number of matching prefix bits
 */
static unsigned int ipv6_match_len ( struct ipv6_miniroute *miniroute,
                                     struct in6_addr *address ) {
        unsigned int match_len = 0;
        unsigned int i;
        uint32_t diff;

        for ( i = 0 ; i < ( sizeof ( address->s6_addr32 ) /
                            sizeof ( address->s6_addr32[0] ) ) ; i++ ) {

                diff = ntohl ( ~( ( ~( address->s6_addr32[i] ^
                                       miniroute->address.s6_addr32[i] ) )
                                  & miniroute->prefix_mask.s6_addr32[i] ) );
                match_len += 32;
                if ( diff ) {
                        match_len -= flsl ( diff );
                        break;
                }
        }

        return match_len;
}

/**
 * Find IPv6 routing table entry for a given address
 *
 * @v netdev            Network device
 * @v address           IPv6 address
 * @ret miniroute       Routing table entry, or NULL if not found
 */
static struct ipv6_miniroute * ipv6_miniroute ( struct net_device *netdev,
                                                struct in6_addr *address ) {
        struct ipv6_miniroute *miniroute;
        unsigned int match_len;

        list_for_each_entry ( miniroute, &ipv6_miniroutes, list ) {
                if ( miniroute->netdev != netdev )
                        continue;
                match_len = ipv6_match_len ( miniroute, address );
                if ( match_len < miniroute->prefix_len )
                        continue;
                return miniroute;
        }
        return NULL;
}

/**
 * Add IPv6 routing table entry
 *
 * @v netdev            Network device
 * @v address           IPv6 address (or prefix)
 * @v prefix_len        Prefix length
 * @v router            Router address (if any)
 * @ret rc              Return status code
 */
int ipv6_add_miniroute ( struct net_device *netdev, struct in6_addr *address,
                         unsigned int prefix_len, struct in6_addr *router ) {
        struct ipv6_miniroute *miniroute;
        uint8_t *prefix_mask;
        unsigned int remaining;
        unsigned int i;

        /* Find or create routing table entry */
        miniroute = ipv6_miniroute ( netdev, address );
        if ( miniroute ) {

                /* Remove from existing position in routing table */
                list_del ( &miniroute->list );

        } else {

                /* Create new routing table entry */
                miniroute = zalloc ( sizeof ( *miniroute ) );
                if ( ! miniroute )
                        return -ENOMEM;
                miniroute->netdev = netdev_get ( netdev );
                memcpy ( &miniroute->address, address,
                         sizeof ( miniroute->address ) );

                /* Default to prefix length of 64 if none specified */
                if ( ! prefix_len )
                        prefix_len = IPV6_DEFAULT_PREFIX_LEN;
                miniroute->prefix_len = prefix_len;
                assert ( prefix_len <= IPV6_MAX_PREFIX_LEN );

                /* Construct prefix mask */
                remaining = prefix_len;
                for ( prefix_mask = miniroute->prefix_mask.s6_addr ;
                      remaining >= 8 ; prefix_mask++, remaining -= 8 ) {
                        *prefix_mask = 0xff;
                }
                if ( remaining )
                        *prefix_mask = ( 0xff << ( 8 - remaining ) );
        }

        /* Add to start of routing table */
        list_add ( &miniroute->list, &ipv6_miniroutes );

        /* Set or update address, if applicable */
        for ( i = 0 ; i < ( sizeof ( address->s6_addr32 ) /
                            sizeof ( address->s6_addr32[0] ) ) ; i++ ) {
                if ( ( address->s6_addr32[i] &
                       ~miniroute->prefix_mask.s6_addr32[i] ) != 0 ) {
                        memcpy ( &miniroute->address, address,
                                 sizeof ( miniroute->address ) );
                        miniroute->flags |= IPV6_HAS_ADDRESS;
                }
        }
        if ( miniroute->prefix_len == IPV6_MAX_PREFIX_LEN )
                miniroute->flags |= IPV6_HAS_ADDRESS;

        /* Update scope */
        miniroute->scope = ipv6_scope ( &miniroute->address );

        /* Set or update router, if applicable */
        if ( router ) {
                memcpy ( &miniroute->router, router,
                         sizeof ( miniroute->router ) );
                miniroute->flags |= IPV6_HAS_ROUTER;
        }

        ipv6_dump_miniroute ( miniroute );
        return 0;
}

/**
 * Delete IPv6 minirouting table entry
 *
 * @v miniroute         Routing table entry
 */
void ipv6_del_miniroute ( struct ipv6_miniroute *miniroute ) {

        netdev_put ( miniroute->netdev );
        list_del ( &miniroute->list );
        free ( miniroute );
}

/**
 * Perform IPv6 routing
 *
 * @v scope_id          Destination address scope ID (for link-local addresses)
 * @v dest              Final destination address
 * @ret dest            Next hop destination address
 * @ret miniroute       Routing table entry to use, or NULL if no route
 */
struct ipv6_miniroute * ipv6_route ( unsigned int scope_id,
                                     struct in6_addr **dest ) {
        struct ipv6_miniroute *miniroute;
        struct ipv6_miniroute *chosen = NULL;
        unsigned int best = 0;
        unsigned int match_len;
        unsigned int score;
        unsigned int scope;

        /* Calculate destination address scope */
        scope = ipv6_scope ( *dest );

        /* Find first usable route in routing table */
        list_for_each_entry ( miniroute, &ipv6_miniroutes, list ) {

                /* Skip closed network devices */
                if ( ! netdev_is_open ( miniroute->netdev ) )
                        continue;

                /* Skip entries with no usable source address */
                if ( ! ( miniroute->flags & IPV6_HAS_ADDRESS ) )
                        continue;

                /* Skip entries with a non-matching scope ID, if
                 * destination specifies a scope ID.
                 */
                if ( scope_id && ( miniroute->netdev->scope_id != scope_id ) )
                        continue;

                /* Skip entries that are out of scope */
                if ( miniroute->scope < scope )
                        continue;

                /* Calculate match length */
                match_len = ipv6_match_len ( miniroute, *dest );

                /* If destination is on-link, then use this route */
                if ( match_len >= miniroute->prefix_len )
                        return miniroute;

                /* If destination is unicast, then skip off-link
                 * entries with no router.
                 */
                if ( ! ( IN6_IS_ADDR_MULTICAST ( *dest ) ||
                         ( miniroute->flags & IPV6_HAS_ROUTER ) ) )
                        continue;

                /* Choose best route, defined as being the route with
                 * the smallest viable scope.  If two routes both have
                 * the same scope, then prefer the route with the
                 * longest match length.
                 */
                score = ( ( ( IPV6_SCOPE_MAX + 1 - miniroute->scope ) << 8 )
                          + match_len );
                if ( score > best ) {
                        chosen = miniroute;
                        best = score;
                }
        }

        /* Return chosen route, if any */
        if ( chosen ) {
                if ( ! IN6_IS_ADDR_MULTICAST ( *dest ) )
                        *dest = &chosen->router;
                return chosen;
        }

        return NULL;
}

/**
 * Determine transmitting network device
 *
 * @v st_dest           Destination network-layer address
 * @ret netdev          Transmitting network device, or NULL
 */
static struct net_device * ipv6_netdev ( struct sockaddr_tcpip *st_dest ) {
        struct sockaddr_in6 *sin6_dest = ( ( struct sockaddr_in6 * ) st_dest );
        struct in6_addr *dest = &sin6_dest->sin6_addr;
        struct ipv6_miniroute *miniroute;

        /* Find routing table entry */
        miniroute = ipv6_route ( sin6_dest->sin6_scope_id, &dest );
        if ( ! miniroute )
                return NULL;

        return miniroute->netdev;
}

/**
 * Check that received options can be safely ignored
 *
 * @v iphdr             IPv6 header
 * @v options           Options extension header
 * @v len               Maximum length of header
 * @ret rc              Return status code
 */
static int ipv6_check_options ( struct ipv6_header *iphdr,
                                struct ipv6_options_header *options,
                                size_t len ) {
        struct ipv6_option *option = options->options;
        struct ipv6_option *end = ( ( ( void * ) options ) + len );

        while ( option < end ) {
                if ( ! IPV6_CAN_IGNORE_OPT ( option->type ) ) {
                        DBGC ( ipv6col ( &iphdr->src ), "IPv6 unrecognised "
                               "option type %#02x:\n", option->type );
                        DBGC_HDA ( ipv6col ( &iphdr->src ), 0,
                                   options, len );
                        return -ENOTSUP_OPT;
                }
                if ( option->type == IPV6_OPT_PAD1 ) {
                        option = ( ( ( void * ) option ) + 1 );
                } else {
                        option = ( ( ( void * ) option->value ) + option->len );
                }
        }
        return 0;
}

/**
 * Check if fragment matches fragment reassembly buffer
 *
 * @v fragment          Fragment reassembly buffer
 * @v iobuf             I/O buffer
 * @v hdrlen            Length of non-fragmentable potion of I/O buffer
 * @ret is_fragment     Fragment matches this reassembly buffer
 */
static int ipv6_is_fragment ( struct fragment *fragment,
                              struct io_buffer *iobuf, size_t hdrlen ) {
        struct ipv6_header *frag_iphdr = fragment->iobuf->data;
        struct ipv6_fragment_header *frag_fhdr =
                ( fragment->iobuf->data + fragment->hdrlen -
                  sizeof ( *frag_fhdr ) );
        struct ipv6_header *iphdr = iobuf->data;
        struct ipv6_fragment_header *fhdr =
                ( iobuf->data + hdrlen - sizeof ( *fhdr ) );

        return ( ( memcmp ( &iphdr->src, &frag_iphdr->src,
                            sizeof ( iphdr->src ) ) == 0 ) &&
                 ( fhdr->ident == frag_fhdr->ident ) );
}

/**
 * Get fragment offset
 *
 * @v iobuf             I/O buffer
 * @v hdrlen            Length of non-fragmentable potion of I/O buffer
 * @ret offset          Offset
 */
static size_t ipv6_fragment_offset ( struct io_buffer *iobuf, size_t hdrlen ) {
        struct ipv6_fragment_header *fhdr =
                ( iobuf->data + hdrlen - sizeof ( *fhdr ) );

        return ( ntohs ( fhdr->offset_more ) & IPV6_MASK_OFFSET );
}

/**
 * Check if more fragments exist
 *
 * @v iobuf             I/O buffer
 * @v hdrlen            Length of non-fragmentable potion of I/O buffer
 * @ret more_frags      More fragments exist
 */
static int ipv6_more_fragments ( struct io_buffer *iobuf, size_t hdrlen ) {
        struct ipv6_fragment_header *fhdr =
                ( iobuf->data + hdrlen - sizeof ( *fhdr ) );

        return ( fhdr->offset_more & htons ( IPV6_MASK_MOREFRAGS ) );
}

/** Fragment reassembler */
static struct fragment_reassembler ipv6_reassembler = {
        .list = LIST_HEAD_INIT ( ipv6_reassembler.list ),
        .is_fragment = ipv6_is_fragment,
        .fragment_offset = ipv6_fragment_offset,
        .more_fragments = ipv6_more_fragments,
        .stats = &ipv6_stats,
};

/**
 * Calculate IPv6 pseudo-header checksum
 *
 * @v iphdr             IPv6 header
 * @v len               Payload length
 * @v next_header       Next header type
 * @v csum              Existing checksum
 * @ret csum            Updated checksum
 */
static uint16_t ipv6_pshdr_chksum ( struct ipv6_header *iphdr, size_t len,
                                    int next_header, uint16_t csum ) {
        struct ipv6_pseudo_header pshdr;

        /* Build pseudo-header */
        memcpy ( &pshdr.src, &iphdr->src, sizeof ( pshdr.src ) );
        memcpy ( &pshdr.dest, &iphdr->dest, sizeof ( pshdr.dest ) );
        pshdr.len = htonl ( len );
        memset ( pshdr.zero, 0, sizeof ( pshdr.zero ) );
        pshdr.next_header = next_header;

        /* Update the checksum value */
        return tcpip_continue_chksum ( csum, &pshdr, sizeof ( pshdr ) );
}

/**
 * Transmit IPv6 packet
 *
 * @v iobuf             I/O buffer
 * @v tcpip             Transport-layer protocol
 * @v st_src            Source network-layer address
 * @v st_dest           Destination network-layer address
 * @v netdev            Network device to use if no route found, or NULL
 * @v trans_csum        Transport-layer checksum to complete, or NULL
 * @ret rc              Status
 *
 * This function expects a transport-layer segment and prepends the
 * IPv6 header
 */
static int ipv6_tx ( struct io_buffer *iobuf,
                     struct tcpip_protocol *tcpip_protocol,
                     struct sockaddr_tcpip *st_src,
                     struct sockaddr_tcpip *st_dest,
                     struct net_device *netdev,
                     uint16_t *trans_csum ) {
        struct sockaddr_in6 *sin6_src = ( ( struct sockaddr_in6 * ) st_src );
        struct sockaddr_in6 *sin6_dest = ( ( struct sockaddr_in6 * ) st_dest );
        struct ipv6_miniroute *miniroute;
        struct ipv6_header *iphdr;
        struct in6_addr *src = NULL;
        struct in6_addr *next_hop;
        uint8_t ll_dest_buf[MAX_LL_ADDR_LEN];
        const void *ll_dest;
        size_t len;
        int rc;

        /* Update statistics */
        ipv6_stats.out_requests++;

        /* Fill up the IPv6 header, except source address */
        len = iob_len ( iobuf );
        iphdr = iob_push ( iobuf, sizeof ( *iphdr ) );
        memset ( iphdr, 0, sizeof ( *iphdr ) );
        iphdr->ver_tc_label = htonl ( IPV6_VER );
        iphdr->len = htons ( len );
        iphdr->next_header = tcpip_protocol->tcpip_proto;
        iphdr->hop_limit = IPV6_HOP_LIMIT;
        memcpy ( &iphdr->dest, &sin6_dest->sin6_addr, sizeof ( iphdr->dest ) );

        /* Use routing table to identify next hop and transmitting netdev */
        next_hop = &iphdr->dest;
        if ( ( miniroute = ipv6_route ( sin6_dest->sin6_scope_id,
                                        &next_hop ) ) != NULL ) {
                src = &miniroute->address;
                netdev = miniroute->netdev;
        }
        if ( ! netdev ) {
                DBGC ( ipv6col ( &iphdr->dest ), "IPv6 has no route to %s\n",
                       inet6_ntoa ( &iphdr->dest ) );
                ipv6_stats.out_no_routes++;
                rc = -ENETUNREACH;
                goto err;
        }
        if ( sin6_src && ! IN6_IS_ADDR_UNSPECIFIED ( &sin6_src->sin6_addr ) )
                src = &sin6_src->sin6_addr;
        if ( src )
                memcpy ( &iphdr->src, src, sizeof ( iphdr->src ) );

        /* Fix up checksums */
        if ( trans_csum ) {
                *trans_csum = ipv6_pshdr_chksum ( iphdr, len,
                                                  tcpip_protocol->tcpip_proto,
                                                  *trans_csum );
                if ( ! *trans_csum )
                        *trans_csum = tcpip_protocol->zero_csum;
        }

        /* Print IPv6 header for debugging */
        DBGC2 ( ipv6col ( &iphdr->dest ), "IPv6 TX %s->",
                inet6_ntoa ( &iphdr->src ) );
        DBGC2 ( ipv6col ( &iphdr->dest ), "%s len %zd next %d\n",
                inet6_ntoa ( &iphdr->dest ), len, iphdr->next_header );

        /* Calculate link-layer destination address, if possible */
        if ( IN6_IS_ADDR_MULTICAST ( next_hop ) ) {
                /* Multicast address */
                ipv6_stats.out_mcast_pkts++;
                if ( ( rc = netdev->ll_protocol->mc_hash ( AF_INET6, next_hop,
                                                           ll_dest_buf ) ) !=0){
                        DBGC ( ipv6col ( &iphdr->dest ), "IPv6 could not hash "
                               "multicast %s: %s\n", inet6_ntoa ( next_hop ),
                               strerror ( rc ) );
                        goto err;
                }
                ll_dest = ll_dest_buf;
        } else {
                /* Unicast address */
                ll_dest = NULL;
        }

        /* Update statistics */
        ipv6_stats.out_transmits++;
        ipv6_stats.out_octets += iob_len ( iobuf );

        /* Hand off to link layer (via NDP if applicable) */
        if ( ll_dest ) {
                if ( ( rc = net_tx ( iobuf, netdev, &ipv6_protocol, ll_dest,
                                     netdev->ll_addr ) ) != 0 ) {
                        DBGC ( ipv6col ( &iphdr->dest ), "IPv6 could not "
                               "transmit packet via %s: %s\n",
                               netdev->name, strerror ( rc ) );
                        return rc;
                }
        } else {
                if ( ( rc = ndp_tx ( iobuf, netdev, next_hop,
                                     &iphdr->src ) ) != 0 ) {
                        DBGC ( ipv6col ( &iphdr->dest ), "IPv6 could not "
                               "transmit packet via %s: %s\n",
                               netdev->name, strerror ( rc ) );
                        return rc;
                }
        }

        return 0;

 err:
        free_iob ( iobuf );
        return rc;
}

/**
 * Process incoming IPv6 packets
 *
 * @v iobuf             I/O buffer
 * @v netdev            Network device
 * @v ll_dest           Link-layer destination address
 * @v ll_source         Link-layer destination source
 * @v flags             Packet flags
 * @ret rc              Return status code
 *
 * This function expects an IPv6 network datagram. It processes the
 * headers and sends it to the transport layer.
 */
static int ipv6_rx ( struct io_buffer *iobuf, struct net_device *netdev,
                     const void *ll_dest __unused,
                     const void *ll_source __unused,
                     unsigned int flags __unused ) {
        struct ipv6_header *iphdr = iobuf->data;
        union ipv6_extension_header *ext;
        union {
                struct sockaddr_in6 sin6;
                struct sockaddr_tcpip st;
        } src, dest;
        uint16_t pshdr_csum;
        size_t len;
        size_t hdrlen;
        size_t extlen;
        int this_header;
        int next_header;
        int rc;

        /* Update statistics */
        ipv6_stats.in_receives++;
        ipv6_stats.in_octets += iob_len ( iobuf );
        if ( flags & LL_BROADCAST ) {
                ipv6_stats.in_bcast_pkts++;
        } else if ( flags & LL_MULTICAST ) {
                ipv6_stats.in_mcast_pkts++;
        }

        /* Sanity check the IPv6 header */
        if ( iob_len ( iobuf ) < sizeof ( *iphdr ) ) {
                DBGC ( ipv6col ( &iphdr->src ), "IPv6 packet too short at %zd "
                       "bytes (min %zd bytes)\n", iob_len ( iobuf ),
                       sizeof ( *iphdr ) );
                rc = -EINVAL_LEN;
                goto err_header;
        }
        if ( ( iphdr->ver_tc_label & htonl ( IPV6_MASK_VER ) ) !=
             htonl ( IPV6_VER ) ) {
                DBGC ( ipv6col ( &iphdr->src ), "IPv6 version %#08x not "
                       "supported\n", ntohl ( iphdr->ver_tc_label ) );
                rc = -ENOTSUP_VER;
                goto err_header;
        }

        /* Truncate packet to specified length */
        len = ntohs ( iphdr->len );
        if ( len > iob_len ( iobuf ) ) {
                DBGC ( ipv6col ( &iphdr->src ), "IPv6 length too long at %zd "
                       "bytes (packet is %zd bytes)\n", len, iob_len ( iobuf ));
                ipv6_stats.in_truncated_pkts++;
                rc = -EINVAL_LEN;
                goto err_other;
        }
        iob_unput ( iobuf, ( iob_len ( iobuf ) - len - sizeof ( *iphdr ) ) );
        hdrlen = sizeof ( *iphdr );

        /* Print IPv6 header for debugging */
        DBGC2 ( ipv6col ( &iphdr->src ), "IPv6 RX %s<-",
                inet6_ntoa ( &iphdr->dest ) );
        DBGC2 ( ipv6col ( &iphdr->src ), "%s len %zd next %d\n",
                inet6_ntoa ( &iphdr->src ), len, iphdr->next_header );

        /* Discard unicast packets not destined for us */
        if ( ( ! ( flags & LL_MULTICAST ) ) &&
             ( ! ipv6_has_addr ( netdev, &iphdr->dest ) ) ) {
                DBGC ( ipv6col ( &iphdr->src ), "IPv6 discarding non-local "
                       "unicast packet for %s\n", inet6_ntoa ( &iphdr->dest ) );
                ipv6_stats.in_addr_errors++;
                rc = -EPIPE;
                goto err_other;
        }

        /* Process any extension headers */
        next_header = iphdr->next_header;
        while ( 1 ) {

                /* Extract extension header */
                this_header = next_header;
                ext = ( iobuf->data + hdrlen );
                extlen = sizeof ( ext->pad );
                if ( iob_len ( iobuf ) < ( hdrlen + extlen ) ) {
                        DBGC ( ipv6col ( &iphdr->src ), "IPv6 too short for "
                               "extension header type %d at %zd bytes (min "
                               "%zd bytes)\n", this_header,
                               ( iob_len ( iobuf ) - hdrlen ), extlen );
                        rc = -EINVAL_LEN;
                        goto err_header;
                }

                /* Determine size of extension header (if applicable) */
                if ( ( this_header == IPV6_HOPBYHOP ) ||
                     ( this_header == IPV6_DESTINATION ) ||
                     ( this_header == IPV6_ROUTING ) ) {
                        /* Length field is present */
                        extlen += ext->common.len;
                } else if ( this_header == IPV6_FRAGMENT ) {
                        /* Length field is reserved and ignored (RFC2460) */
                } else {
                        /* Not an extension header; assume rest is payload */
                        break;
                }
                if ( iob_len ( iobuf ) < ( hdrlen + extlen ) ) {
                        DBGC ( ipv6col ( &iphdr->src ), "IPv6 too short for "
                               "extension header type %d at %zd bytes (min "
                               "%zd bytes)\n", this_header,
                               ( iob_len ( iobuf ) - hdrlen ), extlen );
                        rc = -EINVAL_LEN;
                        goto err_header;
                }
                hdrlen += extlen;
                next_header = ext->common.next_header;
                DBGC2 ( ipv6col ( &iphdr->src ), "IPv6 RX %s<-",
                        inet6_ntoa ( &iphdr->dest ) );
                DBGC2 ( ipv6col ( &iphdr->src ), "%s ext type %d len %zd next "
                        "%d\n", inet6_ntoa ( &iphdr->src ), this_header,
                        extlen, next_header );

                /* Process this extension header */
                if ( ( this_header == IPV6_HOPBYHOP ) ||
                     ( this_header == IPV6_DESTINATION ) ) {

                        /* Check that all options can be ignored */
                        if ( ( rc = ipv6_check_options ( iphdr, &ext->options,
                                                         extlen ) ) != 0 )
                                goto err_header;

                } else if ( this_header == IPV6_FRAGMENT ) {

                        /* Reassemble fragments */
                        iobuf = fragment_reassemble ( &ipv6_reassembler, iobuf,
                                                      &hdrlen );
                        if ( ! iobuf )
                                return 0;
                        iphdr = iobuf->data;
                }
        }

        /* Construct socket address, calculate pseudo-header checksum,
         * and hand off to transport layer
         */
        memset ( &src, 0, sizeof ( src ) );
        src.sin6.sin6_family = AF_INET6;
        memcpy ( &src.sin6.sin6_addr, &iphdr->src,
                 sizeof ( src.sin6.sin6_addr ) );
        src.sin6.sin6_scope_id = netdev->scope_id;
        memset ( &dest, 0, sizeof ( dest ) );
        dest.sin6.sin6_family = AF_INET6;
        memcpy ( &dest.sin6.sin6_addr, &iphdr->dest,
                 sizeof ( dest.sin6.sin6_addr ) );
        dest.sin6.sin6_scope_id = netdev->scope_id;
        iob_pull ( iobuf, hdrlen );
        pshdr_csum = ipv6_pshdr_chksum ( iphdr, iob_len ( iobuf ),
                                         next_header, TCPIP_EMPTY_CSUM );
        if ( ( rc = tcpip_rx ( iobuf, netdev, next_header, &src.st, &dest.st,
                               pshdr_csum, &ipv6_stats ) ) != 0 ) {
                DBGC ( ipv6col ( &src.sin6.sin6_addr ), "IPv6 received packet "
                                "rejected by stack: %s\n", strerror ( rc ) );
                return rc;
        }

        return 0;

 err_header:
        ipv6_stats.in_hdr_errors++;
 err_other:
        free_iob ( iobuf );
        return rc;
}

/**
 * Parse IPv6 address
 *
 * @v string            IPv6 address string
 * @ret in              IPv6 address to fill in
 * @ret rc              Return status code
 */
int inet6_aton ( const char *string, struct in6_addr *in ) {
        uint16_t *word = in->s6_addr16;
        uint16_t *end = ( word + ( sizeof ( in->s6_addr16 ) /
                                   sizeof ( in->s6_addr16[0] ) ) );
        uint16_t *pad = NULL;
        const char *nptr = string;
        char *endptr;
        unsigned long value;
        size_t pad_len;
        size_t move_len;

        /* Parse string */
        while ( 1 ) {

                /* Parse current word */
                value = strtoul ( nptr, &endptr, 16 );
                if ( value > 0xffff ) {
                        DBG ( "IPv6 invalid word value %#lx in \"%s\"\n",
                              value, string );
                        return -EINVAL;
                }
                *(word++) = htons ( value );

                /* Parse separator */
                if ( ! *endptr )
                        break;
                if ( *endptr != ':' ) {
                        DBG ( "IPv6 invalid separator '%c' in \"%s\"\n",
                              *endptr, string );
                        return -EINVAL;
                }
                if ( ( endptr == nptr ) && ( nptr != string ) ) {
                        if ( pad ) {
                                DBG ( "IPv6 invalid multiple \"::\" in "
                                      "\"%s\"\n", string );
                                return -EINVAL;
                        }
                        pad = word;
                }
                nptr = ( endptr + 1 );

                /* Check for overrun */
                if ( word == end ) {
                        DBG ( "IPv6 too many words in \"%s\"\n", string );
                        return -EINVAL;
                }
        }

        /* Insert padding if specified */
        if ( pad ) {
                move_len = ( ( ( void * ) word ) - ( ( void * ) pad ) );
                pad_len = ( ( ( void * ) end ) - ( ( void * ) word ) );
                memmove ( ( ( ( void * ) pad ) + pad_len ), pad, move_len );
                memset ( pad, 0, pad_len );
        } else if ( word != end ) {
                DBG ( "IPv6 underlength address \"%s\"\n", string );
                return -EINVAL;
        }

        return 0;
}

/**
 * Convert IPv6 address to standard notation
 *
 * @v in                IPv6 address
 * @ret string          IPv6 address string in canonical format
 *
 * RFC5952 defines the canonical format for IPv6 textual representation.
 */
char * inet6_ntoa ( const struct in6_addr *in ) {
        static char buf[41]; /* ":xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx" */
        char *out = buf;
        char *longest_start = NULL;
        char *start = NULL;
        int longest_len = 1;
        int len = 0;
        char *dest;
        unsigned int i;
        uint16_t value;

        /* Format address, keeping track of longest run of zeros */
        for ( i = 0 ; i < ( sizeof ( in->s6_addr16 ) /
                            sizeof ( in->s6_addr16[0] ) ) ; i++ ) {
                value = ntohs ( in->s6_addr16[i] );
                if ( value == 0 ) {
                        if ( len++ == 0 )
                                start = out;
                        if ( len > longest_len ) {
                                longest_start = start;
                                longest_len = len;
                        }
                } else {
                        len = 0;
                }
                out += sprintf ( out, ":%x", value );
        }

        /* Abbreviate longest run of zeros, if applicable */
        if ( longest_start ) {
                dest = strcpy ( ( longest_start + 1 ),
                                ( longest_start + ( 2 * longest_len ) ) );
                if ( dest[0] == '\0' )
                        dest[1] = '\0';
                dest[0] = ':';
        }
        return ( ( longest_start == buf ) ? buf : ( buf + 1 ) );
}

/**
 * Transcribe IPv6 address
 *
 * @v net_addr          IPv6 address
 * @ret string          IPv6 address in standard notation
 *
 */
static const char * ipv6_ntoa ( const void *net_addr ) {
        return inet6_ntoa ( net_addr );
}

/**
 * Transcribe IPv6 socket address
 *
 * @v sa                Socket address
 * @ret string          Socket address in standard notation
 */
static const char * ipv6_sock_ntoa ( struct sockaddr *sa ) {
        static char buf[ 39 /* "xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx" */ +
                         1 /* "%" */ + NETDEV_NAME_LEN + 1 /* NUL */ ];
        struct sockaddr_in6 *sin6 = ( ( struct sockaddr_in6 * ) sa );
        struct in6_addr *in = &sin6->sin6_addr;
        struct net_device *netdev;
        const char *netdev_name;

        /* Identify network device, if applicable */
        if ( IN6_IS_ADDR_LINKLOCAL ( in ) || IN6_IS_ADDR_MULTICAST ( in ) ) {
                netdev = find_netdev_by_scope_id ( sin6->sin6_scope_id );
                netdev_name = ( netdev ? netdev->name : "UNKNOWN" );
        } else {
                netdev_name = NULL;
        }

        /* Format socket address */
        snprintf ( buf, sizeof ( buf ), "%s%s%s", inet6_ntoa ( in ),
                   ( netdev_name ? "%" : "" ),
                   ( netdev_name ? netdev_name : "" ) );
        return buf;
}

/**
 * Parse IPv6 socket address
 *
 * @v string            Socket address string
 * @v sa                Socket address to fill in
 * @ret rc              Return status code
 */
static int ipv6_sock_aton ( const char *string, struct sockaddr *sa ) {
        struct sockaddr_in6 *sin6 = ( ( struct sockaddr_in6 * ) sa );
        struct in6_addr in;
        struct net_device *netdev;
        size_t len;
        char *tmp;
        char *in_string;
        char *netdev_string;
        int rc;

        /* Create modifiable copy of string */
        tmp = strdup ( string );
        if ( ! tmp ) {
                rc = -ENOMEM;
                goto err_alloc;
        }
        in_string = tmp;

        /* Strip surrounding "[...]", if present */
        len = strlen ( in_string );
        if ( ( in_string[0] == '[' ) && ( in_string[ len - 1 ] == ']' ) ) {
                in_string[ len - 1 ] = '\0';
                in_string++;
        }

        /* Split at network device name, if present */
        netdev_string = strchr ( in_string, '%' );
        if ( netdev_string )
                *(netdev_string++) = '\0';

        /* Parse IPv6 address portion */
        if ( ( rc = inet6_aton ( in_string, &in ) ) != 0 )
                goto err_inet6_aton;

        /* Parse scope ID, if applicable */
        if ( netdev_string ) {

                /* Parse explicit network device name, if present */
                netdev = find_netdev ( netdev_string );
                if ( ! netdev ) {
                        rc = -ENODEV;
                        goto err_find_netdev;
                }
                sin6->sin6_scope_id = netdev->scope_id;

        } else if ( IN6_IS_ADDR_LINKLOCAL ( &in ) ||
                    IN6_IS_ADDR_MULTICAST ( &in ) ) {

                /* If no network device is explicitly specified for a
                 * link-local or multicast address, default to using
                 * "netX" (if existent).
                 */
                netdev = last_opened_netdev();
                if ( netdev )
                        sin6->sin6_scope_id = netdev->scope_id;
        }

        /* Copy IPv6 address portion to socket address */
        memcpy ( &sin6->sin6_addr, &in, sizeof ( sin6->sin6_addr ) );

 err_find_netdev:
 err_inet6_aton:
        free ( tmp );
 err_alloc:
        return rc;
}

/** IPv6 protocol */
struct net_protocol ipv6_protocol __net_protocol = {
        .name = "IPv6",
        .net_proto = htons ( ETH_P_IPV6 ),
        .net_addr_len = sizeof ( struct in6_addr ),
        .rx = ipv6_rx,
        .ntoa = ipv6_ntoa,
};

/** IPv6 TCPIP net protocol */
struct tcpip_net_protocol ipv6_tcpip_protocol __tcpip_net_protocol = {
        .name = "IPv6",
        .sa_family = AF_INET6,
        .header_len = sizeof ( struct ipv6_header ),
        .net_protocol = &ipv6_protocol,
        .tx = ipv6_tx,
        .netdev = ipv6_netdev,
};

/** IPv6 socket address converter */
struct sockaddr_converter ipv6_sockaddr_converter __sockaddr_converter = {
        .family = AF_INET6,
        .ntoa = ipv6_sock_ntoa,
        .aton = ipv6_sock_aton,
};

/**
 * Parse IPv6 address setting value
 *
 * @v type              Setting type
 * @v value             Formatted setting value
 * @v buf               Buffer to contain raw value
 * @v len               Length of buffer
 * @ret len             Length of raw value, or negative error
 */
int parse_ipv6_setting ( const struct setting_type *type __unused,
                         const char *value, void *buf, size_t len ) {
        struct in6_addr ipv6;
        int rc;

        /* Parse IPv6 address */
        if ( ( rc = inet6_aton ( value, &ipv6 ) ) != 0 )
                return rc;

        /* Copy to buffer */
        if ( len > sizeof ( ipv6 ) )
                len = sizeof ( ipv6 );
        memcpy ( buf, &ipv6, len );

        return ( sizeof ( ipv6 ) );
}

/**
 * Format IPv6 address setting value
 *
 * @v type              Setting type
 * @v raw               Raw setting value
 * @v raw_len           Length of raw setting value
 * @v buf               Buffer to contain formatted value
 * @v len               Length of buffer
 * @ret len             Length of formatted value, or negative error
 */
int format_ipv6_setting ( const struct setting_type *type __unused,
                          const void *raw, size_t raw_len, char *buf,
                          size_t len ) {
        const struct in6_addr *ipv6 = raw;

        if ( raw_len < sizeof ( *ipv6 ) )
                return -EINVAL;
        return snprintf ( buf, len, "%s", inet6_ntoa ( ipv6 ) );
}

/** IPv6 settings scope */
const struct settings_scope ipv6_settings_scope;

/** IPv6 address setting */
const struct setting ip6_setting __setting ( SETTING_IP6, ip6 ) = {
        .name = "ip6",
        .description = "IPv6 address",
        .type = &setting_type_ipv6,
        .scope = &ipv6_settings_scope,
};

/** IPv6 prefix length setting */
const struct setting len6_setting __setting ( SETTING_IP6, len6 ) = {
        .name = "len6",
        .description = "IPv6 prefix length",
        .type = &setting_type_int8,
        .scope = &ipv6_settings_scope,
};

/** Default gateway setting */
const struct setting gateway6_setting __setting ( SETTING_IP6, gateway6 ) = {
        .name = "gateway6",
        .description = "IPv6 gateway",
        .type = &setting_type_ipv6,
        .scope = &ipv6_settings_scope,
};

/**
 * Check applicability of IPv6 link-local address setting
 *
 * @v settings          Settings block
 * @v setting           Setting to fetch
 * @ret applies         Setting applies within this settings block
 */
static int ipv6_applies ( struct settings *settings __unused,
                          const struct setting *setting ) {

        return ( setting->scope == &ipv6_settings_scope );
}

/**
 * Fetch IPv6 link-local address 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 ipv6_fetch ( struct settings *settings, struct setting *setting,
                        void *data, size_t len ) {
        struct net_device *netdev =
                container_of ( settings->parent, struct net_device,
                               settings.settings );
        struct in6_addr ip6;
        uint8_t *len6;
        int prefix_len;
        int rc;

        /* Construct link-local address from EUI-64 as per RFC 2464 */
        memset ( &ip6, 0, sizeof ( ip6 ) );
        prefix_len = ipv6_link_local ( &ip6, netdev );
        if ( prefix_len < 0 ) {
                rc = prefix_len;
                return rc;
        }

        /* Handle setting */
        if ( setting_cmp ( setting, &ip6_setting ) == 0 ) {

                /* Return link-local ip6 */
                if ( len > sizeof ( ip6 ) )
                        len = sizeof ( ip6 );
                memcpy ( data, &ip6, len );
                return sizeof ( ip6 );

        } else if ( setting_cmp ( setting, &len6_setting ) == 0 ) {

                /* Return prefix length */
                if ( len ) {
                        len6 = data;
                        *len6 = prefix_len;
                }
                return sizeof ( *len6 );

        }

        return -ENOENT;
}

/** IPv6 link-local address settings operations */
static struct settings_operations ipv6_settings_operations = {
        .applies = ipv6_applies,
        .fetch = ipv6_fetch,
};

/**
 * Register IPv6 link-local address settings
 *
 * @v netdev            Network device
 * @v priv              Private data
 * @ret rc              Return status code
 */
static int ipv6_register_settings ( struct net_device *netdev, void *priv ) {
        struct settings *parent = netdev_settings ( netdev );
        struct settings *settings = priv;
        int rc;

        /* Initialise and register settings */
        settings_init ( settings, &ipv6_settings_operations,
                        &netdev->refcnt, &ipv6_settings_scope );
        settings->order = IPV6_ORDER_LINK_LOCAL;
        if ( ( rc = register_settings ( settings, parent,
                                        IPV6_SETTINGS_NAME ) ) != 0 )
                return rc;

        return 0;
}

/** IPv6 network device driver */
struct net_driver ipv6_driver __net_driver = {
        .name = "IPv6",
        .priv_len = sizeof ( struct settings ),
        .probe = ipv6_register_settings,
};

/**
 * Create IPv6 routing table based on configured settings
 *
 * @v netdev            Network device
 * @v settings          Settings block
 * @ret rc              Return status code
 */
static int ipv6_create_routes ( struct net_device *netdev,
                                struct settings *settings ) {
        struct settings *child;
        struct settings *origin;
        struct in6_addr ip6_buf;
        struct in6_addr gateway6_buf;
        struct in6_addr *ip6 = &ip6_buf;
        struct in6_addr *gateway6 = &gateway6_buf;
        uint8_t len6;
        size_t len;
        int rc;

        /* First, create routing table for any child settings.  We do
         * this depth-first and in reverse order so that the end
         * result reflects the relative priorities of the settings
         * blocks.
         */
        list_for_each_entry_reverse ( child, &settings->children, siblings )
                ipv6_create_routes ( netdev, child );

        /* Fetch IPv6 address, if any */
        len = fetch_setting ( settings, &ip6_setting, &origin, NULL,
                              ip6, sizeof ( *ip6 ) );
        if ( ( len != sizeof ( *ip6 ) ) || ( origin != settings ) )
                return 0;

        /* Fetch prefix length, if defined */
        len = fetch_setting ( settings, &len6_setting, &origin, NULL,
                              &len6, sizeof ( len6 ) );
        if ( ( len != sizeof ( len6 ) ) || ( origin != settings ) )
                len6 = 0;
        if ( len6 > IPV6_MAX_PREFIX_LEN )
                len6 = IPV6_MAX_PREFIX_LEN;

        /* Fetch gateway, if defined */
        len = fetch_setting ( settings, &gateway6_setting, &origin, NULL,
                              gateway6, sizeof ( *gateway6 ) );
        if ( ( len != sizeof ( *gateway6 ) ) || ( origin != settings ) )
                gateway6 = NULL;

        /* Create or update route */
        if ( ( rc = ipv6_add_miniroute ( netdev, ip6, len6, gateway6 ) ) != 0){
                DBGC ( netdev, "IPv6 %s could not add route: %s\n",
                       netdev->name, strerror ( rc ) );
                return rc;
        }

        return 0;
}

/**
 * Create IPv6 routing table based on configured settings
 *
 * @ret rc              Return status code
 */
static int ipv6_create_all_routes ( void ) {
        struct ipv6_miniroute *miniroute;
        struct ipv6_miniroute *tmp;
        struct net_device *netdev;
        struct settings *settings;
        int rc;

        /* Delete all existing routes */
        list_for_each_entry_safe ( miniroute, tmp, &ipv6_miniroutes, list )
                ipv6_del_miniroute ( miniroute );

        /* Create routes for each configured network device */
        for_each_netdev ( netdev ) {
                settings = netdev_settings ( netdev );
                if ( ( rc = ipv6_create_routes ( netdev, settings ) ) != 0 )
                        return rc;
        }

        return 0;
}

/** IPv6 settings applicator */
struct settings_applicator ipv6_settings_applicator __settings_applicator = {
        .apply = ipv6_create_all_routes,
};

/* Drag in objects via ipv6_protocol */
REQUIRING_SYMBOL ( ipv6_protocol );

/* Drag in ICMPv6 */
REQUIRE_OBJECT ( icmpv6 );

/* Drag in NDP */
REQUIRE_OBJECT ( ndp );