iapp.c

Go to the documentation of this file.

/*
 * hostapd / IEEE 802.11F-2003 Inter-Access Point Protocol (IAPP)
 * Copyright (c) 2002-2007, Jouni Malinen <j@w1.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Alternatively, this software may be distributed under the terms of BSD
 * license.
 *
 * See README and COPYING for more details.
 *
 * Note: IEEE 802.11F-2003 was a experimental use specification. It has expired
 * and IEEE has withdrawn it. In other words, it is likely better to look at
 * using some other mechanism for AP-to-AP communication than extending the
 * implementation here.
 */

/* TODO:
 * Level 1: no administrative or security support
 *      (e.g., static BSSID to IP address mapping in each AP)
 * Level 2: support for dynamic mapping of BSSID to IP address
 * Level 3: support for encryption and authentication of IAPP messages
 * - add support for MOVE-notify and MOVE-response (this requires support for
 *   finding out IP address for previous AP using RADIUS)
 * - add support for Send- and ACK-Security-Block to speedup IEEE 802.1X during
 *   reassociation to another AP
 * - implement counters etc. for IAPP MIB
 * - verify endianness of fields in IAPP messages; are they big-endian as
 *   used here?
 * - RADIUS connection for AP registration and BSSID to IP address mapping
 * - TCP connection for IAPP MOVE, CACHE
 * - broadcast ESP for IAPP ADD-notify
 * - ESP for IAPP MOVE messages
 * - security block sending/processing
 * - IEEE 802.11 context transfer
 */

#include "utils/includes.h"
#include <net/if.h>
#include <sys/ioctl.h>
#ifdef USE_KERNEL_HEADERS
#include <linux/if_packet.h>
#else /* USE_KERNEL_HEADERS */
#include <netpacket/packet.h>
#endif /* USE_KERNEL_HEADERS */

#include "utils/common.h"
#include "utils/eloop.h"
#include "common/ieee802_11_defs.h"
#include "hostapd.h"
#include "ap_config.h"
#include "ieee802_11.h"
#include "sta_info.h"
#include "iapp.h"


#define IAPP_MULTICAST "224.0.1.178"
#define IAPP_UDP_PORT 3517
#define IAPP_TCP_PORT 3517

struct iapp_hdr {
        u8 version;
        u8 command;
        be16 identifier;
        be16 length;
        /* followed by length-6 octets of data */
} __attribute__ ((packed));

#define IAPP_VERSION 0

enum IAPP_COMMAND {
        IAPP_CMD_ADD_notify = 0,
        IAPP_CMD_MOVE_notify = 1,
        IAPP_CMD_MOVE_response = 2,
        IAPP_CMD_Send_Security_Block = 3,
        IAPP_CMD_ACK_Security_Block = 4,
        IAPP_CMD_CACHE_notify = 5,
        IAPP_CMD_CACHE_response = 6,
};


/* ADD-notify - multicast UDP on the local LAN */
struct iapp_add_notify {
        u8 addr_len; /* ETH_ALEN */
        u8 reserved;
        u8 mac_addr[ETH_ALEN];
        be16 seq_num;
} __attribute__ ((packed));


/* Layer 2 Update frame (802.2 Type 1 LLC XID Update response) */
struct iapp_layer2_update {
        u8 da[ETH_ALEN]; /* broadcast */
        u8 sa[ETH_ALEN]; /* STA addr */
        be16 len; /* 6 */
        u8 dsap; /* null DSAP address */
        u8 ssap; /* null SSAP address, CR=Response */
        u8 control;
        u8 xid_info[3];
} __attribute__ ((packed));


/* MOVE-notify - unicast TCP */
struct iapp_move_notify {
        u8 addr_len; /* ETH_ALEN */
        u8 reserved;
        u8 mac_addr[ETH_ALEN];
        u16 seq_num;
        u16 ctx_block_len;
        /* followed by ctx_block_len bytes */
} __attribute__ ((packed));


/* MOVE-response - unicast TCP */
struct iapp_move_response {
        u8 addr_len; /* ETH_ALEN */
        u8 status;
        u8 mac_addr[ETH_ALEN];
        u16 seq_num;
        u16 ctx_block_len;
        /* followed by ctx_block_len bytes */
} __attribute__ ((packed));

enum {
        IAPP_MOVE_SUCCESSFUL = 0,
        IAPP_MOVE_DENIED = 1,
        IAPP_MOVE_STALE_MOVE = 2,
};


/* CACHE-notify */
struct iapp_cache_notify {
        u8 addr_len; /* ETH_ALEN */
        u8 reserved;
        u8 mac_addr[ETH_ALEN];
        u16 seq_num;
        u8 current_ap[ETH_ALEN];
        u16 ctx_block_len;
        /* ctx_block_len bytes of context block followed by 16-bit context
         * timeout */
} __attribute__ ((packed));


/* CACHE-response - unicast TCP */
struct iapp_cache_response {
        u8 addr_len; /* ETH_ALEN */
        u8 status;
        u8 mac_addr[ETH_ALEN];
        u16 seq_num;
} __attribute__ ((packed));

enum {
        IAPP_CACHE_SUCCESSFUL = 0,
        IAPP_CACHE_STALE_CACHE = 1,
};


/* Send-Security-Block - unicast TCP */
struct iapp_send_security_block {
        u8 iv[8];
        u16 sec_block_len;
        /* followed by sec_block_len bytes of security block */
} __attribute__ ((packed));


/* ACK-Security-Block - unicast TCP */
struct iapp_ack_security_block {
        u8 iv[8];
        u8 new_ap_ack_authenticator[48];
} __attribute__ ((packed));


struct iapp_data {
        struct hostapd_data *hapd;
        u16 identifier; /* next IAPP identifier */
        struct in_addr own, multicast;
        int udp_sock;
        int packet_sock;
};


static void iapp_send_add(struct iapp_data *iapp, u8 *mac_addr, u16 seq_num)
{
        char buf[128];
        struct iapp_hdr *hdr;
        struct iapp_add_notify *add;
        struct sockaddr_in addr;

        /* Send IAPP ADD-notify to remove possible association from other APs
         */

        hdr = (struct iapp_hdr *) buf;
        hdr->version = IAPP_VERSION;
        hdr->command = IAPP_CMD_ADD_notify;
        hdr->identifier = host_to_be16(iapp->identifier++);
        hdr->length = host_to_be16(sizeof(*hdr) + sizeof(*add));

        add = (struct iapp_add_notify *) (hdr + 1);
        add->addr_len = ETH_ALEN;
        add->reserved = 0;
        os_memcpy(add->mac_addr, mac_addr, ETH_ALEN);

        add->seq_num = host_to_be16(seq_num);
        
        os_memset(&addr, 0, sizeof(addr));
        addr.sin_family = AF_INET;
        addr.sin_addr.s_addr = iapp->multicast.s_addr;
        addr.sin_port = htons(IAPP_UDP_PORT);
        if (sendto(iapp->udp_sock, buf, (char *) (add + 1) - buf, 0,
                   (struct sockaddr *) &addr, sizeof(addr)) < 0)
                perror("sendto[IAPP-ADD]");
}


static void iapp_send_layer2_update(struct iapp_data *iapp, u8 *addr)
{
        struct iapp_layer2_update msg;

        /* Send Level 2 Update Frame to update forwarding tables in layer 2
         * bridge devices */

        /* 802.2 Type 1 Logical Link Control (LLC) Exchange Identifier (XID)
         * Update response frame; IEEE Std 802.2-1998, 5.4.1.2.1 */

        os_memset(msg.da, 0xff, ETH_ALEN);
        os_memcpy(msg.sa, addr, ETH_ALEN);
        msg.len = host_to_be16(6);
        msg.dsap = 0; /* NULL DSAP address */
        msg.ssap = 0x01; /* NULL SSAP address, CR Bit: Response */
        msg.control = 0xaf; /* XID response lsb.1111F101.
                             * F=0 (no poll command; unsolicited frame) */
        msg.xid_info[0] = 0x81; /* XID format identifier */
        msg.xid_info[1] = 1; /* LLC types/classes: Type 1 LLC */
        msg.xid_info[2] = 1 << 1; /* XID sender's receive window size (RW)
                                   * FIX: what is correct RW with 802.11? */

        if (send(iapp->packet_sock, &msg, sizeof(msg), 0) < 0)
                perror("send[L2 Update]");
}


void iapp_new_station(struct iapp_data *iapp, struct sta_info *sta)
{
        struct ieee80211_mgmt *assoc;
        u16 seq;

        if (iapp == NULL)
                return;

        assoc = sta->last_assoc_req;
        seq = assoc ? WLAN_GET_SEQ_SEQ(le_to_host16(assoc->seq_ctrl)) : 0;

        /* IAPP-ADD.request(MAC Address, Sequence Number, Timeout) */
        hostapd_logger(iapp->hapd, sta->addr, HOSTAPD_MODULE_IAPP,
                       HOSTAPD_LEVEL_DEBUG, "IAPP-ADD.request(seq=%d)", seq);
        iapp_send_layer2_update(iapp, sta->addr);
        iapp_send_add(iapp, sta->addr, seq);

        if (assoc && WLAN_FC_GET_STYPE(le_to_host16(assoc->frame_control)) ==
            WLAN_FC_STYPE_REASSOC_REQ) {
                /* IAPP-MOVE.request(MAC Address, Sequence Number, Old AP,
                 *                   Context Block, Timeout)
                 */
                /* TODO: Send IAPP-MOVE to the old AP; Map Old AP BSSID to
                 * IP address */
        }
}


static void iapp_process_add_notify(struct iapp_data *iapp,
                                    struct sockaddr_in *from,
                                    struct iapp_hdr *hdr, int len)
{
        struct iapp_add_notify *add = (struct iapp_add_notify *) (hdr + 1);
        struct sta_info *sta;

        if (len != sizeof(*add)) {
                printf("Invalid IAPP-ADD packet length %d (expected %lu)\n",
                       len, (unsigned long) sizeof(*add));
                return;
        }

        sta = ap_get_sta(iapp->hapd, add->mac_addr);

        /* IAPP-ADD.indication(MAC Address, Sequence Number) */
        hostapd_logger(iapp->hapd, add->mac_addr, HOSTAPD_MODULE_IAPP,
                       HOSTAPD_LEVEL_INFO,
                       "Received IAPP ADD-notify (seq# %d) from %s:%d%s",
                       be_to_host16(add->seq_num),
                       inet_ntoa(from->sin_addr), ntohs(from->sin_port),
                       sta ? "" : " (STA not found)");

        if (!sta)
                return;

        /* TODO: could use seq_num to try to determine whether last association
         * to this AP is newer than the one advertised in IAPP-ADD. Although,
         * this is not really a reliable verification. */

        hostapd_logger(iapp->hapd, add->mac_addr, HOSTAPD_MODULE_IAPP,
                       HOSTAPD_LEVEL_DEBUG,
                       "Removing STA due to IAPP ADD-notify");
        ap_sta_disconnect(iapp->hapd, sta, NULL, 0);
}


static void iapp_receive_udp(int sock, void *eloop_ctx, void *sock_ctx)
{
        struct iapp_data *iapp = eloop_ctx;
        int len, hlen;
        unsigned char buf[128];
        struct sockaddr_in from;
        socklen_t fromlen;
        struct iapp_hdr *hdr;

        /* Handle incoming IAPP frames (over UDP/IP) */

        fromlen = sizeof(from);
        len = recvfrom(iapp->udp_sock, buf, sizeof(buf), 0,
                       (struct sockaddr *) &from, &fromlen);
        if (len < 0) {
                perror("recvfrom");
                return;
        }

        if (from.sin_addr.s_addr == iapp->own.s_addr)
                return; /* ignore own IAPP messages */

        hostapd_logger(iapp->hapd, NULL, HOSTAPD_MODULE_IAPP,
                       HOSTAPD_LEVEL_DEBUG,
                       "Received %d byte IAPP frame from %s%s\n",
                       len, inet_ntoa(from.sin_addr),
                       len < (int) sizeof(*hdr) ? " (too short)" : "");

        if (len < (int) sizeof(*hdr))
                return;

        hdr = (struct iapp_hdr *) buf;
        hlen = be_to_host16(hdr->length);
        hostapd_logger(iapp->hapd, NULL, HOSTAPD_MODULE_IAPP,
                       HOSTAPD_LEVEL_DEBUG,
                       "RX: version=%d command=%d id=%d len=%d\n",
                       hdr->version, hdr->command,
                       be_to_host16(hdr->identifier), hlen);
        if (hdr->version != IAPP_VERSION) {
                printf("Dropping IAPP frame with unknown version %d\n",
                       hdr->version);
                return;
        }
        if (hlen > len) {
                printf("Underflow IAPP frame (hlen=%d len=%d)\n", hlen, len);
                return;
        }
        if (hlen < len) {
                printf("Ignoring %d extra bytes from IAPP frame\n",
                       len - hlen);
                len = hlen;
        }

        switch (hdr->command) {
        case IAPP_CMD_ADD_notify:
                iapp_process_add_notify(iapp, &from, hdr, hlen - sizeof(*hdr));
                break;
        case IAPP_CMD_MOVE_notify:
                /* TODO: MOVE is using TCP; so move this to TCP handler once it
                 * is implemented.. */
                /* IAPP-MOVE.indication(MAC Address, New BSSID,
                 * Sequence Number, AP Address, Context Block) */
                /* TODO: process */
                break;
        default:
                printf("Unknown IAPP command %d\n", hdr->command);
                break;
        }
}


struct iapp_data * iapp_init(struct hostapd_data *hapd, const char *iface)
{
        struct ifreq ifr;
        struct sockaddr_ll addr;
        int ifindex;
        struct sockaddr_in *paddr, uaddr;
        struct iapp_data *iapp;
        struct ip_mreqn mreq;

        iapp = os_zalloc(sizeof(*iapp));
        if (iapp == NULL)
                return NULL;
        iapp->hapd = hapd;
        iapp->udp_sock = iapp->packet_sock = -1;

        /* TODO:
         * open socket for sending and receiving IAPP frames over TCP
         */

        iapp->udp_sock = socket(PF_INET, SOCK_DGRAM, 0);
        if (iapp->udp_sock < 0) {
                perror("socket[PF_INET,SOCK_DGRAM]");
                iapp_deinit(iapp);
                return NULL;
        }

        os_memset(&ifr, 0, sizeof(ifr));
        os_strlcpy(ifr.ifr_name, iface, sizeof(ifr.ifr_name));
        if (ioctl(iapp->udp_sock, SIOCGIFINDEX, &ifr) != 0) {
                perror("ioctl(SIOCGIFINDEX)");
                iapp_deinit(iapp);
                return NULL;
        }
        ifindex = ifr.ifr_ifindex;

        if (ioctl(iapp->udp_sock, SIOCGIFADDR, &ifr) != 0) {
                perror("ioctl(SIOCGIFADDR)");
                iapp_deinit(iapp);
                return NULL;
        }
        paddr = (struct sockaddr_in *) &ifr.ifr_addr;
        if (paddr->sin_family != AF_INET) {
                printf("Invalid address family %i (SIOCGIFADDR)\n",
                       paddr->sin_family);
                iapp_deinit(iapp);
                return NULL;
        }
        iapp->own.s_addr = paddr->sin_addr.s_addr;

        if (ioctl(iapp->udp_sock, SIOCGIFBRDADDR, &ifr) != 0) {
                perror("ioctl(SIOCGIFBRDADDR)");
                iapp_deinit(iapp);
                return NULL;
        }
        paddr = (struct sockaddr_in *) &ifr.ifr_addr;
        if (paddr->sin_family != AF_INET) {
                printf("Invalid address family %i (SIOCGIFBRDADDR)\n",
                       paddr->sin_family);
                iapp_deinit(iapp);
                return NULL;
        }
        inet_aton(IAPP_MULTICAST, &iapp->multicast);

        os_memset(&uaddr, 0, sizeof(uaddr));
        uaddr.sin_family = AF_INET;
        uaddr.sin_port = htons(IAPP_UDP_PORT);
        if (bind(iapp->udp_sock, (struct sockaddr *) &uaddr,
                 sizeof(uaddr)) < 0) {
                perror("bind[UDP]");
                iapp_deinit(iapp);
                return NULL;
        }

        os_memset(&mreq, 0, sizeof(mreq));
        mreq.imr_multiaddr = iapp->multicast;
        mreq.imr_address.s_addr = INADDR_ANY;
        mreq.imr_ifindex = 0;
        if (setsockopt(iapp->udp_sock, SOL_IP, IP_ADD_MEMBERSHIP, &mreq,
                       sizeof(mreq)) < 0) {
                perror("setsockopt[UDP,IP_ADD_MEMBERSHIP]");
                iapp_deinit(iapp);
                return NULL;
        }

        iapp->packet_sock = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
        if (iapp->packet_sock < 0) {
                perror("socket[PF_PACKET,SOCK_RAW]");
                iapp_deinit(iapp);
                return NULL;
        }

        os_memset(&addr, 0, sizeof(addr));
        addr.sll_family = AF_PACKET;
        addr.sll_ifindex = ifindex;
        if (bind(iapp->packet_sock, (struct sockaddr *) &addr,
                 sizeof(addr)) < 0) {
                perror("bind[PACKET]");
                iapp_deinit(iapp);
                return NULL;
        }

        if (eloop_register_read_sock(iapp->udp_sock, iapp_receive_udp,
                                     iapp, NULL)) {
                printf("Could not register read socket for IAPP.\n");
                iapp_deinit(iapp);
                return NULL;
        }

        printf("IEEE 802.11F (IAPP) using interface %s\n", iface);

        /* TODO: For levels 2 and 3: send RADIUS Initiate-Request, receive
         * RADIUS Initiate-Accept or Initiate-Reject. IAPP port should actually
         * be openned only after receiving Initiate-Accept. If Initiate-Reject
         * is received, IAPP is not started. */

        return iapp;
}


void iapp_deinit(struct iapp_data *iapp)
{
        struct ip_mreqn mreq;

        if (iapp == NULL)
                return;

        if (iapp->udp_sock >= 0) {
                os_memset(&mreq, 0, sizeof(mreq));
                mreq.imr_multiaddr = iapp->multicast;
                mreq.imr_address.s_addr = INADDR_ANY;
                mreq.imr_ifindex = 0;
                if (setsockopt(iapp->udp_sock, SOL_IP, IP_DROP_MEMBERSHIP,
                               &mreq, sizeof(mreq)) < 0) {
                        perror("setsockopt[UDP,IP_DEL_MEMBERSHIP]");
                }

                eloop_unregister_read_sock(iapp->udp_sock);
                close(iapp->udp_sock);
        }
        if (iapp->packet_sock >= 0) {
                eloop_unregister_read_sock(iapp->packet_sock);
                close(iapp->packet_sock);
        }
        os_free(iapp);
}