diff options
Diffstat (limited to 'gpxe/src/net/ndp.c')
-rw-r--r-- | gpxe/src/net/ndp.c | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/gpxe/src/net/ndp.c b/gpxe/src/net/ndp.c new file mode 100644 index 00000000..8bea8b32 --- /dev/null +++ b/gpxe/src/net/ndp.c @@ -0,0 +1,180 @@ +#include <stdint.h> +#include <string.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> + +/** @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; +}; + +/** 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; + +/** + * 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; +} + +/** + * 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 ) ); +} + +/** + * 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; +} + +/** + * Process neighbour advertisement + * + * @v iobuf I/O buffer + * @v st_src Source address + * @v st_dest Destination address + */ +int ndp_process_advert ( struct io_buffer *iobuf, struct sockaddr_tcpip *st_src __unused, + struct sockaddr_tcpip *st_dest __unused ) { + struct neighbour_advert *nadvert = iobuf->data; + struct ndp_entry *ndp; + + /* Sanity check */ + if ( iob_len ( iobuf ) < sizeof ( *nadvert ) ) { + DBG ( "Packet too short (%zd bytes)\n", iob_len ( iobuf ) ); + return -EINVAL; + } + + assert ( nadvert->code == 0 ); + assert ( nadvert->flags & ICMP6_FLAGS_SOLICITED ); + assert ( nadvert->opt_type == 2 ); + + /* Update the neighbour cache, if entry is present */ + ndp = ndp_find_entry ( &nadvert->target ); + if ( ndp ) { + + assert ( nadvert->opt_len == + ( ( 2 + ndp->ll_protocol->ll_addr_len ) / 8 ) ); + + if ( IP6_EQUAL ( ndp->in6, nadvert->target ) ) { + memcpy ( ndp->ll_addr, nadvert->opt_ll_addr, + ndp->ll_protocol->ll_addr_len ); + ndp->state = NDP_STATE_REACHABLE; + return 0; + } + } + DBG ( "Unsolicited advertisement (dropping packet)\n" ); + return 0; +} |