[ipv6] Enable router solicitations to timeout

[gpxe.git] / src / net / ndp.c

#include <stdint.h>
#include <string.h>
#include <stdlib.h>
#include <byteswap.h>
#include <errno.h>
#include <gpxe/if_ether.h>
#include <gpxe/iobuf.h>
#include <gpxe/ndp.h>
#include <gpxe/icmp6.h>
#include <gpxe/ip6.h>
#include <gpxe/netdevice.h>
#include <gpxe/retry.h>
#include <gpxe/timer.h>
#include <gpxe/job.h>

/** @file
 *
 * Neighbour Discovery Protocol
 *
 * This file implements address resolution as specified by the neighbour
 * discovery protocol in RFC2461. This protocol is part of the IPv6 protocol
 * family.
 */

/* A neighbour entry */
struct ndp_entry {
        /** Target IP6 address */
        struct in6_addr in6;
        /** Link layer protocol */
        struct ll_protocol *ll_protocol;
        /** Link-layer address */
        uint8_t ll_addr[MAX_LL_ADDR_LEN];
        /** State of the neighbour entry */
        int state;
};

/** A pending router solicitation. */
struct pending_rsolicit {
        /** Network device for the solicit. */
        struct net_device *netdev;
        /** State of the solicitation. */
        int state;
        /** Status code after handling the solicit. */
        int code;
        /** Job control interface */
        struct job_interface job;
        /** Reference counter */
        struct refcnt refcnt;
        /** Metadata to fill when we receive an advertisement. */
        struct rsolicit_info *meta;
        /** Timer for timeout handling. */
        struct retry_timer timer;
};

/** Number of entries in the neighbour cache table */
#define NUM_NDP_ENTRIES 4

/** The neighbour cache table */
static struct ndp_entry ndp_table[NUM_NDP_ENTRIES];
#define ndp_table_end &ndp_table[NUM_NDP_ENTRIES]

static unsigned int next_new_ndp_entry = 0;

/** The pending solicit table */
static struct pending_rsolicit solicit_table[NUM_NDP_ENTRIES];
#define solicit_table_end &solicit_table[NUM_NDP_ENTRIES]

static unsigned int next_new_solicit_entry = 0;

/**
 * Handle kill() event received via job control interface
 *
 * @v job               Router solicit job control interface
 */
static void rsolicit_job_kill ( struct job_interface *job ) {
        struct pending_rsolicit *entry =
                container_of ( job, struct pending_rsolicit, job );

        /* Terminate. */
        entry->code = 0;
        entry->state = RSOLICIT_STATE_INVALID;
        
        /* Stop retry timer */
        stop_timer ( &entry->timer );
        
        /* Clean up. */
        job_nullify ( &entry->job );
        job_done ( &entry->job, -ECANCELED );
}

/** Router solicit job control interface operations */
static struct job_interface_operations rsolicit_job_operations = {
        .done           = ignore_job_done,
        .kill           = rsolicit_job_kill,
        .progress       = ignore_job_progress,
};

/**
 * Handle router solicitation timeout. 
 * @v timer     Solicitation retry timer.
 * @v fail      Failure indicator.
 */
static void rsolicit_timer_expired ( struct retry_timer *timer, int fail __unused ) {
        struct pending_rsolicit *entry = 
                container_of ( timer, struct pending_rsolicit, timer );
        
        /* Don't bother retrying. */
        rsolicit_job_kill ( &entry->job );
}

/**
 * Find entry in the neighbour cache
 *
 * @v in6       IP6 address
 */
static struct ndp_entry *
ndp_find_entry ( struct in6_addr *in6 ) {
        struct ndp_entry *ndp;

        for ( ndp = ndp_table ; ndp < ndp_table_end ; ndp++ ) {
                if ( IP6_EQUAL ( ( *in6 ), ndp->in6 ) &&
                     ( ndp->state != NDP_STATE_INVALID ) ) {
                        return ndp;
                }
        }
        return NULL;
}

/**
 * Find a pending router solicitation for an interface.
 *
 * @v netdev    Interface for the solicitation.
 */
static struct pending_rsolicit *
solicit_find_entry ( struct net_device *netdev ) {
        struct pending_rsolicit *entry;

        for ( entry = solicit_table ; entry < solicit_table_end ; entry++ ) {
                if ( ( entry->netdev == netdev ) &&
                     ( entry->state == RSOLICIT_STATE_PENDING ) ) {
                        return entry;
                }
        }
        return NULL;
}

/**
 * Add NDP entry
 *
 * @v netdev    Network device
 * @v in6       IP6 address
 * @v ll_addr   Link-layer address
 * @v state     State of the entry - one of the NDP_STATE_XXX values
 */
static void
add_ndp_entry ( struct net_device *netdev, struct in6_addr *in6,
                void *ll_addr, int state ) {
        struct ndp_entry *ndp;
        ndp = &ndp_table[next_new_ndp_entry++ % NUM_NDP_ENTRIES];

        /* Fill up entry */
        ndp->ll_protocol = netdev->ll_protocol;
        memcpy ( &ndp->in6, &( *in6 ), sizeof ( *in6 ) );
        if ( ll_addr ) {
                memcpy ( ndp->ll_addr, ll_addr, netdev->ll_protocol->ll_addr_len );
        } else {
                memset ( ndp->ll_addr, 0, netdev->ll_protocol->ll_addr_len );
        }
        ndp->state = state;
        DBG ( "New neighbour cache entry: IP6 %s => %s %s\n",
              inet6_ntoa ( ndp->in6 ), netdev->ll_protocol->name,
              netdev->ll_protocol->ntoa ( ndp->ll_addr ) );
}

/**
 * Add pending solicit entry
 * 
 * @v netdev    Network device
 * @v state     State of the entry - one of the RSOLICIT_STATE_XXX values
 */
static struct pending_rsolicit *
add_solicit_entry ( struct net_device *netdev, int state ) {
        struct pending_rsolicit *entry;
        entry = &solicit_table[next_new_solicit_entry++ % NUM_NDP_ENTRIES];

        /* Fill up entry */
        entry->netdev = netdev;
        entry->state = state;
        entry->code = RSOLICIT_CODE_NONE;
        entry->meta = NULL;
        
        return entry;
}

/**
 * Resolve the link-layer address
 *
 * @v netdev            Network device
 * @v dest              Destination address
 * @v src               Source address
 * @ret dest_ll_addr    Destination link-layer address or NULL
 * @ret rc              Status
 *
 * This function looks up the neighbour cache for an entry corresponding to the
 * destination address. If it finds a valid entry, it fills up dest_ll_addr and
 * returns 0. Otherwise it sends a neighbour solicitation to the solicited
 * multicast address.
 */
int ndp_resolve ( struct net_device *netdev, struct in6_addr *dest,
                  struct in6_addr *src, void *dest_ll_addr ) {
        struct ll_protocol *ll_protocol = netdev->ll_protocol;
        struct ndp_entry *ndp;
        int rc;

        ndp = ndp_find_entry ( dest );
        /* Check if the entry is valid */
        if ( ndp && ndp->state == NDP_STATE_REACHABLE ) {
                DBG ( "Neighbour cache hit: IP6 %s => %s %s\n",
                      inet6_ntoa ( *dest ), ll_protocol->name,
                      ll_protocol->ntoa ( ndp->ll_addr ) );
                memcpy ( dest_ll_addr, ndp->ll_addr, ll_protocol->ll_addr_len );
                return 0;
        }

        /* Check if the entry was already created */
        if ( ndp ) {
                DBG ( "Awaiting neighbour advertisement\n" );
                /* For test */
//              ndp->state = NDP_STATE_REACHABLE;
//              memcpy ( ndp->ll_addr, netdev->ll_addr, 6 );
//              assert ( ndp->ll_protocol->ll_addr_len == 6 );
//              icmp6_test_nadvert ( netdev, dest, ndp->ll_addr );
//              assert ( ndp->state == NDP_STATE_REACHABLE );
                /* Take it out till here */
                return -ENOENT;
        }
        DBG ( "Neighbour cache miss: IP6 %s\n", inet6_ntoa ( *dest ) );

        /* Add entry in the neighbour cache */
        add_ndp_entry ( netdev, dest, NULL, NDP_STATE_INCOMPLETE );

        /* Send neighbour solicitation */
        if ( ( rc = icmp6_send_solicit ( netdev, src, dest ) ) != 0 ) {
                return rc;
        }
        return -ENOENT;
}

/**
 * Send router solicitation packet
 *
 * @v netdev    Network device
 * @v src       Source address
 * @v meta      (optional) Pointer to struct to fill with information
 *              when an advertisement arrives.
 * @v dest      Destination address
 *
 * This function prepares a neighbour solicitation packet and sends it to the
 * network layer.
 */
int ndp_send_rsolicit ( struct net_device *netdev,
                        struct job_interface *job,
                        struct rsolicit_info *meta ) {
        union {
                struct sockaddr_in6 sin6;
                struct sockaddr_tcpip st;
        } st_dest;
        struct router_solicit *solicit;
        struct io_buffer *iobuf = alloc_iob ( sizeof ( *solicit ) + MIN_IOB_LEN );
        struct pending_rsolicit *entry;
        int rc = 0;
        
        iob_reserve ( iobuf, MAX_HDR_LEN );
        solicit = iob_put ( iobuf, sizeof ( *solicit ) );

        /* Fill up the headers */
        memset ( solicit, 0, sizeof ( *solicit ) );
        solicit->type = ICMP6_ROUTER_SOLICIT;
        solicit->code = 0;
        
        /* Partial checksum */
        solicit->csum = 0;
        solicit->csum = tcpip_chksum ( solicit, sizeof ( *solicit ) );

        /* Solicited multicast address - FF02::2 (all routers on local network) */
        memset(&st_dest.sin6, 0, sizeof(st_dest.sin6));
        st_dest.sin6.sin_family = AF_INET6;
        st_dest.sin6.sin6_addr.in6_u.u6_addr8[0] = 0xff;
        st_dest.sin6.sin6_addr.in6_u.u6_addr8[1] = 0x2;
        st_dest.sin6.sin6_addr.in6_u.u6_addr8[15] = 0x2;
        
        /* Add an entry for this solicitation. */
        entry = add_solicit_entry ( netdev, RSOLICIT_STATE_ALMOST );
        entry->meta = meta;
        
        /* Set up a job for the solicit. */
        job_init ( &entry->job, &rsolicit_job_operations, &entry->refcnt );
        timer_init ( &entry->timer, rsolicit_timer_expired );

        /* Set up the retry timer. */
        stop_timer ( &entry->timer );
        entry->timer.min_timeout = 0;
        entry->timer.max_timeout = 5;
        start_timer ( &entry->timer );
        
        /* Send packet over IP6 */
        rc = ipv6_tx ( iobuf, &icmp6_protocol, NULL, &st_dest.st,
                       netdev, &solicit->csum );
        
        /* Return. */
        if ( rc == 0 ) {
                entry->state = RSOLICIT_STATE_PENDING;
                
                job_plug_plug ( &entry->job, job );
                ref_put ( &entry->refcnt );
                return 0;
        } else {
                entry->state = RSOLICIT_STATE_INVALID;
                
                rsolicit_job_kill ( &entry->job );
                ref_put ( &entry->refcnt );
                return rc;
        }
}

/**
 * Process Router Advertisement
 *
 * @v iobuf I/O buffer containing the data.
 * @v st_src Address of the source station.
 * @v st_dest Address of the destination station. Typically FF02::1.
 */
int ndp_process_radvert ( struct io_buffer *iobuf, struct sockaddr_tcpip *st_src,
                          struct sockaddr_tcpip *st_dest __unused, struct net_device *netdev,
                          struct icmp6_net_protocol *net_protocol __unused ) {
        struct router_advert *radvert = iobuf->data;
        struct ndp_option *options = iobuf->data + sizeof(struct router_advert);
        struct in6_addr router_addr = ( ( struct sockaddr_in6 * ) st_src )->sin6_addr;
        struct in6_addr host_addr, prefix;
        int rc = -ENOENT;
        uint8_t prefix_len = 0;
        size_t offset = sizeof ( struct router_advert ), ll_size;
        int can_autoconf = 0; /* Can we autoconfigure from the prefix? */
        
        /* Verify that there's a pending solicit */
        struct pending_rsolicit *pending = solicit_find_entry ( netdev );
        if ( ! pending ) {
                DBG ( "ndp: unsolicited router advertisement, ignoring\n" );
                return rc;
        }
        
        /* Stop retry timer - we'll complete the job no matter what happens. */
        stop_timer ( &pending->timer );

        memset ( &host_addr, 0, sizeof ( host_addr ) );

        /* Router advertisement flags */
        if ( ntohs ( radvert->hops_flags ) & RADVERT_MANAGED ) {
                DBG ( "ndp: router advertisement suggests DHCPv6\n" );
                pending->code |= RSOLICIT_CODE_MANAGED;
        }
        if ( ntohs ( radvert->hops_flags ) & RADVERT_OTHERCONF ) {
                DBG ( "ndp: router advertisement suggests DHCPv6 for additional information\n" );
                pending->code |= RSOLICIT_CODE_OTHERCONF;
        }

        /* Parse options. */
        while ( offset < iob_len( iobuf ) ) {

                switch ( options->type ) {
                case NDP_OPTION_PREFIX_INFO:
                        {
                        struct prefix_option *opt = (struct prefix_option *) options;

                        prefix_len = opt->prefix_len;

                        if ( prefix_len % 8 ) {
                                /* Copy one extra prefix byte. */
                                prefix_len += 8;
                        }

                        if ( prefix_len > 64 ) {
                                /* > 64-bit prefix shouldn't happen. */
                                DBG ( "ndp: prefix length is quite long, connectivity may suffer.\n" );
                        }

                        /* Copy the prefix first and then add the EUI-64 */
                        memcpy ( &prefix.s6_addr, opt->prefix, prefix_len / 8 );
                        memcpy ( &host_addr.s6_addr, &prefix.s6_addr, prefix_len / 8 );

                        /* Create an IPv6 address for this station based on the prefix. */
                        ll_size = netdev->ll_protocol->ll_addr_len;
                        if ( ll_size < 6 ) {
                                memcpy ( host_addr.s6_addr + (8 - ll_size), netdev->ll_addr, ll_size );
                        } else {
                                ipv6_generate_eui64 ( host_addr.s6_addr + 8, netdev->ll_addr );
                        }
                        
                        /* Get flags. */
                        can_autoconf = opt->flags_rsvd & ( 1 << 6 );
                        if ( ! can_autoconf )
                                DBG ( "ndp: got a prefix, but can't use it for SLAAC\n" );
                        else
                                DBG ( "ndp: can use prefix for SLAAC\n" );

                        rc = 0;
                        }
                        break;

                case NDP_OPTION_SOURCE_LL:
                        {
                        struct ll_option *opt = (struct ll_option *) options;

                        /* Add entry in the neighbour cache for the router */
                        if ( ! ndp_find_entry ( &router_addr ) ) {
                                add_ndp_entry ( netdev, &router_addr, opt->address, NDP_STATE_REACHABLE );
                        }

                        }
                        break;
                }

                offset += options->length * 8;
                options = (struct ndp_option *) (iobuf->data + offset);
        }

        if ( rc ) {
                DBG ( "ndp: couldn't generate a prefix from a router advertisement\n" );
                pending->code = RSOLICIT_CODE_NONE; /* Clear flags. */
                
                job_done ( &pending->job, -ENOENT );
                
                return 0;
        }
        
        /* Fill in information if we need to. */
        if ( pending->meta != NULL ) {
                DBG ( "ndp: filling meta information\n" );
                pending->meta->router = router_addr;
                pending->meta->prefix = prefix;
                pending->meta->prefix_length = prefix_len;
                pending->meta->no_address = ! can_autoconf;
        }

        /* Configure a route based on this router if none exists. */
        if ( can_autoconf && net_protocol->check ( netdev, &host_addr ) ) {
                DBG ( "ndp: autoconfigured %s/%d via a router advertisement\n", inet6_ntoa( host_addr ), prefix_len);

                add_ipv6_address ( netdev, prefix, prefix_len, host_addr, router_addr );
        }
        
        /* Completed without error. */
        job_done ( &pending->job, pending->code );
        pending->state = RSOLICIT_STATE_INVALID;

        return 0;
}

/**
 * Process neighbour advertisement
 *
 * @v iobuf     I/O buffer
 * @v st_src    Source address
 * @v st_dest   Destination address
 */
int ndp_process_nadvert ( struct io_buffer *iobuf, struct sockaddr_tcpip *st_src __unused,
                           struct sockaddr_tcpip *st_dest __unused,
                           struct icmp6_net_protocol *net_protocol __unused ) {
        struct neighbour_advert *nadvert = iobuf->data;
        struct ll_option *ll_opt = iobuf->data + sizeof ( *nadvert );
        struct ndp_entry *ndp;

        /* Sanity check */
        if ( iob_len ( iobuf ) < sizeof ( *nadvert ) ) {
                DBG ( "Packet too short (%zd bytes)\n", iob_len ( iobuf ) );
                return -EINVAL;
        }

        /* FIXME: assumes link-layer option is first. */

        assert ( nadvert->code == 0 );
        assert ( nadvert->flags & ICMP6_FLAGS_SOLICITED );
        assert ( ll_opt->type == 2 );

        /* Update the neighbour cache, if entry is present */
        ndp = ndp_find_entry ( &nadvert->target );
        if ( ndp ) {

        assert ( ll_opt->length ==
                        ( ( 2 + ndp->ll_protocol->ll_addr_len ) / 8 ) );

                if ( IP6_EQUAL ( ndp->in6, nadvert->target ) ) {
                        memcpy ( ndp->ll_addr, ll_opt->address,
                                 ndp->ll_protocol->ll_addr_len );
                        ndp->state = NDP_STATE_REACHABLE;
                        return 0;
                }
        }
        DBG ( "Unsolicited advertisement (dropping packet)\n" );
        return 0;
}

/**
 * Process neighbour solicitation
 *
 * @v iobuf     I/O buffer
 * @v st_src    Source address
 * @v st_dest   Destination address
 * @v netdev    Network device the packet was received on.
 */
int ndp_process_nsolicit ( struct io_buffer *iobuf __unused, struct sockaddr_tcpip *st_src,
                           struct sockaddr_tcpip *st_dest __unused, struct net_device *netdev,
                           struct icmp6_net_protocol *net_protocol ) {
        struct neighbour_solicit *nsolicit = iobuf->data;
        struct in6_addr *src =  &( ( struct sockaddr_in6 * ) st_src )->sin6_addr;

        /* Does this match any addresses on the interface? */
        if ( ! net_protocol->check ( netdev, &nsolicit->target ) ) {
                /* Send an advertisement to the host. */
                DBG ( "ndp: neighbour solicit received for us\n" );
                return icmp6_send_advert ( netdev, &nsolicit->target, src );
        } else {
                DBG ( "ndp: neighbour solicit received but it's not for us\n" );
        }

        return 0;
}