/* #line 1 "./ragel/tnet_dns_resolvconf.rl" */
/*
* Copyright (C) 2010-2015 Mamadou DIOP.
*
* This file is part of Open Source Doubango Framework.
*
* DOUBANGO is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* DOUBANGO 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 DOUBANGO.
*
*/
/**@file tnet_dns_resolvconf.c
 * @brief Parser for "/etc/resolv.conf" file to retrive DNS servers.
 */
#include "tnet_dns_resolvconf.h"

#include "tnet_utils.h"

#include "dns/tnet_dns.h"

#include "tsk_string.h"
#include "tsk_memory.h"
#include "tsk_ragel_state.h"
#include "tsk_debug.h"

#include <string.h>


/* ===	Ragel state machine === */

/* #line 75 "./ragel/tnet_dns_resolvconf.rl" */


/** Gets list of DNS servers from a conf file.
* @param path Path of the conf file from which to retrieve the DNS servers.
* should be @a "/etc/resolv.conf". You can adjust the value by modifying @ref TNET_RESOLV_CONF_PATH.<br>
* If you are using <b>Android</b> and the resolv.conf file is missing, then run the following line in a command window: <br>
* <i>ln -s /private/var/run/resolv.conf /etc/resolv.conf</i><br> If this fails, then try to manually add the file.
* @retval List of DNS servers.
*/
tnet_addresses_L_t * tnet_dns_resolvconf_parse(const char* path)
{
    tnet_addresses_L_t* servers = tsk_null;
    tnet_ip_t ip;
    const char* fullpath = path;
    const char* tag_start = tsk_null;
    FILE* fd;
    char* buf = tsk_null;

    // Ragel
    int cs = 0;
    const char *p;
    const char *pe;
    const char *eof;

    TSK_RAGEL_DISABLE_WARNINGS_BEGIN()

    /* #line 69 "./src/dns/tnet_dns_resolvconf.c" */
    static const char _tdns_machine_resolvconf_actions[] = {
        0, 1, 0, 1, 1
    };

    static const char _tdns_machine_resolvconf_key_offsets[] = {
        0, 7, 8, 9, 12, 15, 15, 22,
        24, 27, 30, 33, 36, 39, 42, 45,
        48, 51, 52, 53, 56
    };

    static const char _tdns_machine_resolvconf_trans_keys[] = {
        10, 13, 32, 35, 59, 78, 110, 32,
        32, 10, 13, 32, 10, 13, 32, 10,
        13, 32, 35, 59, 78, 110, 10, 13,
        32, 65, 97, 32, 77, 109, 32, 69,
        101, 32, 83, 115, 32, 69, 101, 32,
        82, 114, 32, 86, 118, 32, 69, 101,
        32, 82, 114, 32, 32, 10, 13, 32,
        32, 35, 59, 78, 110, 0
    };

    static const char _tdns_machine_resolvconf_single_lengths[] = {
        7, 1, 1, 3, 3, 0, 7, 2,
        3, 3, 3, 3, 3, 3, 3, 3,
        3, 1, 1, 3, 5
    };

    static const char _tdns_machine_resolvconf_range_lengths[] = {
        0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0
    };

    static const char _tdns_machine_resolvconf_index_offsets[] = {
        0, 8, 10, 12, 16, 20, 21, 29,
        32, 36, 40, 44, 48, 52, 56, 60,
        64, 68, 70, 72, 76
    };

    static const char _tdns_machine_resolvconf_indicies[] = {
        1, 1, 2, 3, 3, 4, 4, 0,
        5, 0, 5, 6, 7, 7, 8, 6,
        7, 7, 8, 9, 9, 1, 1, 5,
        3, 3, 4, 4, 0, 7, 7, 3,
        5, 10, 10, 0, 5, 11, 11, 0,
        5, 12, 12, 0, 5, 13, 13, 0,
        5, 14, 14, 0, 5, 15, 15, 0,
        5, 16, 16, 0, 5, 17, 17, 0,
        5, 18, 18, 0, 19, 0, 19, 20,
        22, 22, 23, 21, 2, 3, 3, 4,
        4, 0, 0
    };

    static const char _tdns_machine_resolvconf_trans_targs[] = {
        1, 6, 20, 7, 8, 2, 3, 0,
        4, 5, 9, 10, 11, 12, 13, 14,
        15, 16, 17, 18, 19, 19, 0, 4
    };

    static const char _tdns_machine_resolvconf_trans_actions[] = {
        0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 1, 0, 3, 3
    };

    static const int tdns_machine_resolvconf_start = 0;
    static const int tdns_machine_resolvconf_first_final = 0;
    static const int tdns_machine_resolvconf_error = -1;

    static const int tdns_machine_resolvconf_en_main = 0;


    /* #line 101 "./ragel/tnet_dns_resolvconf.rl" */
    TSK_RAGEL_DISABLE_WARNINGS_END()
    (void)(eof);
    (void)(tdns_machine_resolvconf_first_final);
    (void)(tdns_machine_resolvconf_error);
    (void)(tdns_machine_resolvconf_en_main);

    if(tsk_strnullORempty(fullpath)) {
        fullpath = TNET_RESOLV_CONF_PATH;
    }

    /* Open the file and read all data */
    if((fd = fopen(fullpath, "r"))) {
        long len;
        fseek(fd, 0L, SEEK_END);
        len = ftell(fd);
        fseek(fd, 0L, SEEK_SET);
        if (!(buf = (char*)tsk_calloc(len + 1, 1))) {
            TSK_DEBUG_ERROR("Failed to allocate buffer with size = %ld", (len + 1));
            goto bail;
        }
        fread(buf, 1, len, fd);
        p = &buf[0];
        pe = p + len + 1/*hack*/;
        eof = pe;
        fclose(fd);

        buf[len] = '\n'; // hack to have perfect lines

        servers = tsk_list_create();
    }
    else {
#if ANDROID || defined(__APPLE__) /* TARGET_OS_IPHONE not defined for bsd libraries */
        TSK_DEBUG_INFO("Failed to open [%s]. But don't panic, we have detected that you are using Google Android/iOS Systems.\n"
                       "You should look at the Progammer's Guide for more information.\n If you are not using DNS functions, don't worry about this warning.",
                       fullpath);
#else
        TSK_DEBUG_ERROR("Failed to open %s.", fullpath);
#endif
        goto bail;
    }

    TSK_RAGEL_DISABLE_WARNINGS_BEGIN()

    /* #line 186 "./src/dns/tnet_dns_resolvconf.c" */
    {
        cs = tdns_machine_resolvconf_start;
    }

    /* #line 144 "./ragel/tnet_dns_resolvconf.rl" */

    /* #line 193 "./src/dns/tnet_dns_resolvconf.c" */
    {
        int _klen;
        unsigned int _trans;
        const char *_acts;
        unsigned int _nacts;
        const char *_keys;

        if ( p == pe ) {
            goto _test_eof;
        }
_resume:
        _keys = _tdns_machine_resolvconf_trans_keys + _tdns_machine_resolvconf_key_offsets[cs];
        _trans = _tdns_machine_resolvconf_index_offsets[cs];

        _klen = _tdns_machine_resolvconf_single_lengths[cs];
        if ( _klen > 0 ) {
            const char *_lower = _keys;
            const char *_mid;
            const char *_upper = _keys + _klen - 1;
            while (1) {
                if ( _upper < _lower ) {
                    break;
                }

                _mid = _lower + ((_upper-_lower) >> 1);
                if ( (*p) < *_mid ) {
                    _upper = _mid - 1;
                }
                else if ( (*p) > *_mid ) {
                    _lower = _mid + 1;
                }
                else {
                    _trans += (_mid - _keys);
                    goto _match;
                }
            }
            _keys += _klen;
            _trans += _klen;
        }

        _klen = _tdns_machine_resolvconf_range_lengths[cs];
        if ( _klen > 0 ) {
            const char *_lower = _keys;
            const char *_mid;
            const char *_upper = _keys + (_klen<<1) - 2;
            while (1) {
                if ( _upper < _lower ) {
                    break;
                }

                _mid = _lower + (((_upper-_lower) >> 1) & ~1);
                if ( (*p) < _mid[0] ) {
                    _upper = _mid - 2;
                }
                else if ( (*p) > _mid[1] ) {
                    _lower = _mid + 2;
                }
                else {
                    _trans += ((_mid - _keys)>>1);
                    goto _match;
                }
            }
            _trans += _klen;
        }

_match:
        _trans = _tdns_machine_resolvconf_indicies[_trans];
        cs = _tdns_machine_resolvconf_trans_targs[_trans];

        if ( _tdns_machine_resolvconf_trans_actions[_trans] == 0 ) {
            goto _again;
        }

        _acts = _tdns_machine_resolvconf_actions + _tdns_machine_resolvconf_trans_actions[_trans];
        _nacts = (unsigned int) *_acts++;
        while ( _nacts-- > 0 ) {
            switch ( *_acts++ ) {
            case 0:
                /* #line 41 "./ragel/tnet_dns_resolvconf.rl" */
            {
                tag_start = p;
            }
            break;
            case 1:
                /* #line 45 "./ragel/tnet_dns_resolvconf.rl" */
            {
                int len = (int)(p  - tag_start);
                if(len && len<=sizeof(ip)) {
                    tnet_address_t *address;
                    memset(ip, '\0', sizeof(ip));
                    memcpy(ip, tag_start, len);
                    TSK_DEBUG_INFO("Adding DNS server = %s:%d", ip, TNET_DNS_SERVER_PORT_DEFAULT);

                    address = tnet_address_create(ip);
                    address->family = tnet_get_family(ip, TNET_DNS_SERVER_PORT_DEFAULT);
                    address->dnsserver = 1;
                    tsk_list_push_ascending_data(servers, (void**)&address);
                }
            }
            break;
            /* #line 288 "./src/dns/tnet_dns_resolvconf.c" */
            }
        }

_again:
        if ( ++p != pe ) {
            goto _resume;
        }
_test_eof: {
        }
    }

    /* #line 145 "./ragel/tnet_dns_resolvconf.rl" */
    TSK_RAGEL_DISABLE_WARNINGS_END()

    if (cs <
            /* #line 302 "./src/dns/tnet_dns_resolvconf.c" */
            0
            /* #line 147 "./ragel/tnet_dns_resolvconf.rl" */
       ) {
        TSK_DEBUG_ERROR("Failed to parse %s.", fullpath);
        TSK_OBJECT_SAFE_FREE(servers);
    }

bail:
    TSK_FREE(buf);
    return servers;
}