hdhomerun_discover.c

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/*
 * hdhomerun_discover.c
 *
 * Copyright © 2006-2010 Silicondust USA Inc. <www.silicondust.com>.
 *
 * This library is free software; you can redistribute it and/or 
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 * 
 * As a special exception to the GNU Lesser General Public License,
 * you may link, statically or dynamically, an application with a
 * publicly distributed version of the Library to produce an
 * executable file containing portions of the Library, and
 * distribute that executable file under terms of your choice,
 * without any of the additional requirements listed in clause 4 of
 * the GNU Lesser General Public License.
 * 
 * By "a publicly distributed version of the Library", we mean
 * either the unmodified Library as distributed by Silicondust, or a
 * modified version of the Library that is distributed under the
 * conditions defined in the GNU Lesser General Public License.
 */

#include "hdhomerun.h"

#define HDHOMERUN_DISOCVER_MAX_SOCK_COUNT 16

struct hdhomerun_discover_sock_t {
        hdhomerun_sock_t sock;
        bool_t detected;
        uint32_t local_ip;
        uint32_t subnet_mask;
};

struct hdhomerun_discover_t {
        struct hdhomerun_discover_sock_t socks[HDHOMERUN_DISOCVER_MAX_SOCK_COUNT];
        unsigned int sock_count;
        struct hdhomerun_pkt_t tx_pkt;
        struct hdhomerun_pkt_t rx_pkt;
};

static bool_t hdhomerun_discover_sock_add(struct hdhomerun_discover_t *ds, uint32_t local_ip, uint32_t subnet_mask)
{
        unsigned int i;
        for (i = 1; i < ds->sock_count; i++) {
                struct hdhomerun_discover_sock_t *dss = &ds->socks[i];

                if ((dss->local_ip == local_ip) && (dss->subnet_mask == subnet_mask)) {
                        dss->detected = TRUE;
                        return TRUE;
                }
        }

        if (ds->sock_count >= HDHOMERUN_DISOCVER_MAX_SOCK_COUNT) {
                return FALSE;
        }

        /* Create socket. */
        hdhomerun_sock_t sock = hdhomerun_sock_create_udp();
        if (sock == HDHOMERUN_SOCK_INVALID) {
                return FALSE;
        }

        /* Bind socket. */
        if (!hdhomerun_sock_bind(sock, local_ip, 0, FALSE)) {
                hdhomerun_sock_destroy(sock);
                return FALSE;
        }

        /* Write sock entry. */
        struct hdhomerun_discover_sock_t *dss = &ds->socks[ds->sock_count++];
        dss->sock = sock;
        dss->detected = TRUE;
        dss->local_ip = local_ip;
        dss->subnet_mask = subnet_mask;

        return TRUE;
}

struct hdhomerun_discover_t *hdhomerun_discover_create(void)
{
        struct hdhomerun_discover_t *ds = (struct hdhomerun_discover_t *)calloc(1, sizeof(struct hdhomerun_discover_t));
        if (!ds) {
                return NULL;
        }

        /* Create a routable socket (always first entry). */
        if (!hdhomerun_discover_sock_add(ds, 0, 0)) {
                free(ds);
                return NULL;
        }

        /* Success. */
        return ds;
}

void hdhomerun_discover_destroy(struct hdhomerun_discover_t *ds)
{
        unsigned int i;
        for (i = 0; i < ds->sock_count; i++) {
                struct hdhomerun_discover_sock_t *dss = &ds->socks[i];
                hdhomerun_sock_destroy(dss->sock);
        }

        free(ds);
}

static void hdhomerun_discover_sock_detect(struct hdhomerun_discover_t *ds)
{
        unsigned int i;
        for (i = 1; i < ds->sock_count; i++) {
                struct hdhomerun_discover_sock_t *dss = &ds->socks[i];
                dss->detected = FALSE;
        }

        struct hdhomerun_local_ip_info_t ip_info_list[HDHOMERUN_DISOCVER_MAX_SOCK_COUNT];
        int count = hdhomerun_local_ip_info(ip_info_list, HDHOMERUN_DISOCVER_MAX_SOCK_COUNT);
        if (count < 0) {
                count = 0;
        }

        int index;
        for (index = 0; index < count; index++) {
                struct hdhomerun_local_ip_info_t *ip_info = &ip_info_list[index];
                hdhomerun_discover_sock_add(ds, ip_info->ip_addr, ip_info->subnet_mask);
        }

        struct hdhomerun_discover_sock_t *src = &ds->socks[1];
        struct hdhomerun_discover_sock_t *dst = &ds->socks[1];
        count = 1;
        for (i = 1; i < ds->sock_count; i++) {
                if (!src->detected) {
                        hdhomerun_sock_destroy(src->sock);
                        src++;
                        continue;
                }
                if (dst != src) {
                        *dst = *src;
                }
                src++;
                dst++;
                count++;
        }

        ds->sock_count = count;
}

static bool_t hdhomerun_discover_send_internal(struct hdhomerun_discover_t *ds, struct hdhomerun_discover_sock_t *dss, uint32_t target_ip, uint32_t device_type, uint32_t device_id)
{
        struct hdhomerun_pkt_t *tx_pkt = &ds->tx_pkt;
        hdhomerun_pkt_reset(tx_pkt);

        hdhomerun_pkt_write_u8(tx_pkt, HDHOMERUN_TAG_DEVICE_TYPE);
        hdhomerun_pkt_write_var_length(tx_pkt, 4);
        hdhomerun_pkt_write_u32(tx_pkt, device_type);
        hdhomerun_pkt_write_u8(tx_pkt, HDHOMERUN_TAG_DEVICE_ID);
        hdhomerun_pkt_write_var_length(tx_pkt, 4);
        hdhomerun_pkt_write_u32(tx_pkt, device_id);
        hdhomerun_pkt_seal_frame(tx_pkt, HDHOMERUN_TYPE_DISCOVER_REQ);

        return hdhomerun_sock_sendto(dss->sock, target_ip, HDHOMERUN_DISCOVER_UDP_PORT, tx_pkt->start, tx_pkt->end - tx_pkt->start, 0);
}

static bool_t hdhomerun_discover_send_wildcard_ip(struct hdhomerun_discover_t *ds, uint32_t device_type, uint32_t device_id)
{
        bool_t result = FALSE;

        /*
         * Send subnet broadcast using each local ip socket.
         * This will work with multiple separate 169.254.x.x interfaces.
         */
        unsigned int i;
        for (i = 1; i < ds->sock_count; i++) {
                struct hdhomerun_discover_sock_t *dss = &ds->socks[i];
                uint32_t target_ip = dss->local_ip | ~dss->subnet_mask;
                result |= hdhomerun_discover_send_internal(ds, dss, target_ip, device_type, device_id);
        }

        /*
         * If no local ip sockets then fall back to sending a global broadcast letting the OS choose the interface.
         */
        if (!result) {
                struct hdhomerun_discover_sock_t *dss = &ds->socks[0];
                result = hdhomerun_discover_send_internal(ds, dss, 0xFFFFFFFF, device_type, device_id);
        }

        return result;
}

static bool_t hdhomerun_discover_send_target_ip(struct hdhomerun_discover_t *ds, uint32_t target_ip, uint32_t device_type, uint32_t device_id)
{
        bool_t result = FALSE;

        /*
         * Send targeted packet from any local ip that is in the same subnet.
         * This will work with multiple separate 169.254.x.x interfaces.
         */
        unsigned int i;
        for (i = 1; i < ds->sock_count; i++) {
                struct hdhomerun_discover_sock_t *dss = &ds->socks[i];
                if ((target_ip & dss->subnet_mask) != (dss->local_ip & dss->subnet_mask)) {
                        continue;
                }

                result |= hdhomerun_discover_send_internal(ds, dss, target_ip, device_type, device_id);
        }

        /*
         * If target IP does not match a local subnet then fall back to letting the OS choose the gateway interface.
         */
        if (!result) {
                struct hdhomerun_discover_sock_t *dss = &ds->socks[0];
                result = hdhomerun_discover_send_internal(ds, dss, target_ip, device_type, device_id);
        }

        return result;
}

static bool_t hdhomerun_discover_send(struct hdhomerun_discover_t *ds, uint32_t target_ip, uint32_t device_type, uint32_t device_id)
{
        if (target_ip == 0) {
                return hdhomerun_discover_send_wildcard_ip(ds, device_type, device_id);
        } else {
                return hdhomerun_discover_send_target_ip(ds, target_ip, device_type, device_id);
        }
}

static bool_t hdhomerun_discover_recv_internal(struct hdhomerun_discover_t *ds, struct hdhomerun_discover_sock_t *dss, struct hdhomerun_discover_device_t *result)
{
        struct hdhomerun_pkt_t *rx_pkt = &ds->rx_pkt;
        hdhomerun_pkt_reset(rx_pkt);

        uint32_t remote_addr;
        uint16_t remote_port;
        size_t length = rx_pkt->limit - rx_pkt->end;
        if (!hdhomerun_sock_recvfrom(dss->sock, &remote_addr, &remote_port, rx_pkt->end, &length, 0)) {
                return FALSE;
        }

        rx_pkt->end += length;

        uint16_t type;
        if (hdhomerun_pkt_open_frame(rx_pkt, &type) <= 0) {
                return FALSE;
        }
        if (type != HDHOMERUN_TYPE_DISCOVER_RPY) {
                return FALSE;
        }

        result->ip_addr = remote_addr;
        result->device_type = 0;
        result->device_id = 0;
        result->tuner_count = 0;

        while (1) {
                uint8_t tag;
                size_t len;
                uint8_t *next = hdhomerun_pkt_read_tlv(rx_pkt, &tag, &len);
                if (!next) {
                        break;
                }

                switch (tag) {
                case HDHOMERUN_TAG_DEVICE_TYPE:
                        if (len != 4) {
                                break;
                        }
                        result->device_type = hdhomerun_pkt_read_u32(rx_pkt);
                        break;

                case HDHOMERUN_TAG_DEVICE_ID:
                        if (len != 4) {
                                break;
                        }
                        result->device_id = hdhomerun_pkt_read_u32(rx_pkt);
                        break;

                case HDHOMERUN_TAG_TUNER_COUNT:
                        if (len != 1) {
                                break;
                        }
                        result->tuner_count = hdhomerun_pkt_read_u8(rx_pkt);
                        break;

                default:
                        break;
                }

                rx_pkt->pos = next;
        }

        /* Fixup for old firmware. */
        if (result->tuner_count == 0) {
                switch (result->device_id >> 20) {
                case 0x102:
                        result->tuner_count = 1;
                        break;

                case 0x100:
                case 0x101:
                case 0x121:
                        result->tuner_count = 2;
                        break;

                default:
                        break;
                }
        }

        return TRUE;
}

static bool_t hdhomerun_discover_recv(struct hdhomerun_discover_t *ds, struct hdhomerun_discover_device_t *result)
{
        unsigned int i;
        for (i = 0; i < ds->sock_count; i++) {
                struct hdhomerun_discover_sock_t *dss = &ds->socks[i];

                if (hdhomerun_discover_recv_internal(ds, dss, result)) {
                        return TRUE;
                }
        }

        return FALSE;
}

static struct hdhomerun_discover_device_t *hdhomerun_discover_find_in_list(struct hdhomerun_discover_device_t result_list[], int count, struct hdhomerun_discover_device_t *lookup)
{
        int index;
        for (index = 0; index < count; index++) {
                struct hdhomerun_discover_device_t *entry = &result_list[index];
                if (memcmp(lookup, entry, sizeof(struct hdhomerun_discover_device_t)) == 0) {
                        return entry;
                }
        }

        return NULL;
}

int hdhomerun_discover_find_devices(struct hdhomerun_discover_t *ds, uint32_t target_ip, uint32_t device_type, uint32_t device_id, struct hdhomerun_discover_device_t result_list[], int max_count)
{
        hdhomerun_discover_sock_detect(ds);

        int count = 0;
        int attempt;
        for (attempt = 0; attempt < 2; attempt++) {
                if (!hdhomerun_discover_send(ds, target_ip, device_type, device_id)) {
                        return -1;
                }

                uint64_t timeout = getcurrenttime() + 200;
                while (1) {
                        struct hdhomerun_discover_device_t *result = &result_list[count];
                        memset(result, 0, sizeof(struct hdhomerun_discover_device_t));

                        if (!hdhomerun_discover_recv(ds, result)) {
                                if (getcurrenttime() >= timeout) {
                                        break;
                                }
                                msleep_approx(10);
                                continue;
                        }

                        /* Filter. */
                        if (device_type != HDHOMERUN_DEVICE_TYPE_WILDCARD) {
                                if (device_type != result->device_type) {
                                        continue;
                                }
                        }
                        if (device_id != HDHOMERUN_DEVICE_ID_WILDCARD) {
                                if (device_id != result->device_id) {
                                        continue;
                                }
                        }

                        /* Ensure not already in list. */
                        if (hdhomerun_discover_find_in_list(result_list, count, result)) {
                                continue;
                        }

                        /* Add to list. */
                        count++;
                        if (count >= max_count) {
                                return count;
                        }
                }
        }

        return count;
}

int hdhomerun_discover_find_devices_custom(uint32_t target_ip, uint32_t device_type, uint32_t device_id, struct hdhomerun_discover_device_t result_list[], int max_count)
{
        if (hdhomerun_discover_is_ip_multicast(target_ip)) {
                return 0;
        }

        struct hdhomerun_discover_t *ds = hdhomerun_discover_create();
        if (!ds) {
                return -1;
        }

        int ret = hdhomerun_discover_find_devices(ds, target_ip, device_type, device_id, result_list, max_count);

        hdhomerun_discover_destroy(ds);
        return ret;
}

bool_t hdhomerun_discover_validate_device_id(uint32_t device_id)
{
        static uint32_t lookup_table[16] = {0xA, 0x5, 0xF, 0x6, 0x7, 0xC, 0x1, 0xB, 0x9, 0x2, 0x8, 0xD, 0x4, 0x3, 0xE, 0x0};

        uint32_t checksum = 0;

        checksum ^= lookup_table[(device_id >> 28) & 0x0F];
        checksum ^= (device_id >> 24) & 0x0F;
        checksum ^= lookup_table[(device_id >> 20) & 0x0F];
        checksum ^= (device_id >> 16) & 0x0F;
        checksum ^= lookup_table[(device_id >> 12) & 0x0F];
        checksum ^= (device_id >> 8) & 0x0F;
        checksum ^= lookup_table[(device_id >> 4) & 0x0F];
        checksum ^= (device_id >> 0) & 0x0F;

        return (checksum == 0);
}

bool_t hdhomerun_discover_is_ip_multicast(uint32_t ip_addr)
{
        return (ip_addr >= 0xE0000000) && (ip_addr < 0xF0000000);
}

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