/**
 * @file NCDIfConfig.c
 * @author Ambroz Bizjak <ambrop7@gmail.com>
 * 
 * @section LICENSE
 * 
 * This file is part of BadVPN.
 * 
 * BadVPN 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.
 * 
 * BadVPN 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.
 */

#include <inttypes.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/socket.h>
#include <net/if.h>
#include <net/if_arp.h>
#include <sys/ioctl.h>

#include <misc/debug.h>
#include <system/BLog.h>

#include <ncd/NCDIfConfig.h>

#include <generated/blog_channel_NCDIfConfig.h>

#define IP_CMD "ip"
#define ROUTE_CMD "route"
#define RESOLVCONF_FILE "/etc/resolv.conf"
#define RESOLVCONF_TEMP_FILE "/etc/resolv.conf-ncd-temp"

static int run_command (const char *cmd)
{
    BLog(BLOG_INFO, "run: %s", cmd);
    
    return system(cmd);
}

static int write_to_file (uint8_t *data, size_t data_len, FILE *f)
{
    while (data_len > 0) {
        size_t bytes = fwrite(data, 1, data_len, f);
        if (bytes == 0) {
            return 0;
        }
        data += bytes;
        data_len -= bytes;
    }
}

int NCDIfConfig_query (const char *ifname)
{
    struct ifreq ifr;
    
    int flags = 0;
    
    int s = socket(AF_INET, SOCK_DGRAM, 0);
    if (!s) {
        BLog(BLOG_ERROR, "socket failed");
        goto fail0;
    }
    
    memset(&ifr, 0, sizeof(ifr));
    snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), "%s", ifname);
    if (ioctl(s, SIOCGIFFLAGS, &ifr)) {
        BLog(BLOG_ERROR, "ioctl(SIOCGIFFLAGS) failed");
        goto fail1;
    }
    
    flags |= NCDIFCONFIG_FLAG_EXISTS;
    
    if ((ifr.ifr_flags&IFF_UP)) {
        flags |= NCDIFCONFIG_FLAG_UP;
        
        if ((ifr.ifr_flags&IFF_RUNNING)) {
            flags |= NCDIFCONFIG_FLAG_RUNNING;
        }
    }
    
fail1:
    close(s);
fail0:
    return flags;
}

int NCDIfConfig_set_up (const char *ifname)
{
    char cmd[50 + strlen(ifname)];
    sprintf(cmd, IP_CMD" link set %s up", ifname);
    
    return !run_command(cmd);
}

int NCDIfConfig_set_down (const char *ifname)
{
    char cmd[50 + strlen(ifname)];
    sprintf(cmd, IP_CMD" link set %s down", ifname);
    
    return !run_command(cmd);
}

int NCDIfConfig_add_ipv4_addr (const char *ifname, struct ipv4_ifaddr ifaddr)
{
    ASSERT(ifaddr.prefix >= 0)
    ASSERT(ifaddr.prefix <= 32)
    
    uint8_t *addr = (uint8_t *)&ifaddr.addr;
    
    char cmd[50 + strlen(ifname)];
    sprintf(cmd, IP_CMD" addr add %"PRIu8".%"PRIu8".%"PRIu8".%"PRIu8"/%d dev %s", addr[0], addr[1], addr[2], addr[3], ifaddr.prefix, ifname);
    
    return !run_command(cmd);
}

int NCDIfConfig_remove_ipv4_addr (const char *ifname, struct ipv4_ifaddr ifaddr)
{
    ASSERT(ifaddr.prefix >= 0)
    ASSERT(ifaddr.prefix <= 32)
    
    uint8_t *addr = (uint8_t *)&ifaddr.addr;
    
    char cmd[50 + strlen(ifname)];
    sprintf(cmd, IP_CMD" addr del %"PRIu8".%"PRIu8".%"PRIu8".%"PRIu8"/%d dev %s", addr[0], addr[1], addr[2], addr[3], ifaddr.prefix, ifname);
    
    return !run_command(cmd);
}

int NCDIfConfig_add_ipv4_route (struct ipv4_ifaddr dest, uint32_t gateway, int metric, const char *device)
{
    ASSERT(dest.prefix >= 0)
    ASSERT(dest.prefix <= 32)
    
    uint8_t *d_addr = (uint8_t *)&dest.addr;
    uint8_t *g_addr = (uint8_t *)&gateway;
    
    char cmd[100];
    sprintf(cmd, ROUTE_CMD" add -net %"PRIu8".%"PRIu8".%"PRIu8".%"PRIu8"/%d gw %"PRIu8".%"PRIu8".%"PRIu8".%"PRIu8" metric %d dev %s",
            d_addr[0], d_addr[1], d_addr[2], d_addr[3], dest.prefix, g_addr[0], g_addr[1], g_addr[2], g_addr[3], metric, device);
    
    return !run_command(cmd);
}

int NCDIfConfig_remove_ipv4_route (struct ipv4_ifaddr dest, uint32_t gateway, int metric, const char *device)
{
    ASSERT(dest.prefix >= 0)
    ASSERT(dest.prefix <= 32)
    
    uint8_t *d_addr = (uint8_t *)&dest.addr;
    uint8_t *g_addr = (uint8_t *)&gateway;
    
    char cmd[100];
    sprintf(cmd, ROUTE_CMD" del -net %"PRIu8".%"PRIu8".%"PRIu8".%"PRIu8"/%d gw %"PRIu8".%"PRIu8".%"PRIu8".%"PRIu8" metric %d dev %s",
            d_addr[0], d_addr[1], d_addr[2], d_addr[3], dest.prefix, g_addr[0], g_addr[1], g_addr[2], g_addr[3], metric, device);
    
    return !run_command(cmd);
}

int NCDIfConfig_set_dns_servers (uint32_t *servers, size_t num_servers)
{
    FILE *temp_file = fopen(RESOLVCONF_TEMP_FILE, "w");
    if (!temp_file) {
        BLog(BLOG_ERROR, "failed to open resolvconf temp file");
        goto fail0;
    }
    
    char line[60];
    
    sprintf(line, "# generated by badvpn-ncd\n");
    if (!write_to_file(line, strlen(line), temp_file)) {
        BLog(BLOG_ERROR, "failed to write to resolvconf temp file");
        goto fail1;
    }
    
    for (size_t i = 0; i < num_servers; i++) {
        uint8_t *addr = (uint8_t *)&servers[i];
        sprintf(line, "nameserver %"PRIu8".%"PRIu8".%"PRIu8".%"PRIu8"\n",
                addr[0], addr[1], addr[2], addr[3]);
        if (!write_to_file(line, strlen(line), temp_file)) {
            BLog(BLOG_ERROR, "failed to write to resolvconf temp file");
            goto fail1;
        }
    }
    
    if (fclose(temp_file) != 0) {
        BLog(BLOG_ERROR, "failed to close resolvconf temp file");
        return 0;
    }
    
    if (rename(RESOLVCONF_TEMP_FILE, RESOLVCONF_FILE) < 0) {
        BLog(BLOG_ERROR, "failed to rename resolvconf temp file to resolvconf file");
        return 0;
    }
    
    return 1;
    
fail1:
    fclose(temp_file);
fail0:
    return 0;
}