/* Copyright (C) 2017 Open Information Security Foundation
 *
 * You can copy, redistribute or modify this Program under the terms of
 * the GNU General Public License version 2 as published by the Free
 * Software Foundation.
 *
 * This program 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
 * version 2 along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */

extern crate libc;

use std;
use std::string::String;

use json::*;
use dns::dns::*;

pub const LOG_A          : u64 = BIT_U64!(2);
pub const LOG_NS         : u64 = BIT_U64!(3);
pub const LOG_MD         : u64 = BIT_U64!(4);
pub const LOG_MF         : u64 = BIT_U64!(5);
pub const LOG_CNAME      : u64 = BIT_U64!(6);
pub const LOG_SOA        : u64 = BIT_U64!(7);
pub const LOG_MB         : u64 = BIT_U64!(8);
pub const LOG_MG         : u64 = BIT_U64!(9);
pub const LOG_MR         : u64 = BIT_U64!(10);
pub const LOG_NULL       : u64 = BIT_U64!(11);
pub const LOG_WKS        : u64 = BIT_U64!(12);
pub const LOG_PTR        : u64 = BIT_U64!(13);
pub const LOG_HINFO      : u64 = BIT_U64!(14);
pub const LOG_MINFO      : u64 = BIT_U64!(15);
pub const LOG_MX         : u64 = BIT_U64!(16);
pub const LOG_TXT        : u64 = BIT_U64!(17);
pub const LOG_RP         : u64 = BIT_U64!(18);
pub const LOG_AFSDB      : u64 = BIT_U64!(19);
pub const LOG_X25        : u64 = BIT_U64!(20);
pub const LOG_ISDN       : u64 = BIT_U64!(21);
pub const LOG_RT         : u64 = BIT_U64!(22);
pub const LOG_NSAP       : u64 = BIT_U64!(23);
pub const LOG_NSAPPTR    : u64 = BIT_U64!(24);
pub const LOG_SIG        : u64 = BIT_U64!(25);
pub const LOG_KEY        : u64 = BIT_U64!(26);
pub const LOG_PX         : u64 = BIT_U64!(27);
pub const LOG_GPOS       : u64 = BIT_U64!(28);
pub const LOG_AAAA       : u64 = BIT_U64!(29);
pub const LOG_LOC        : u64 = BIT_U64!(30);
pub const LOG_NXT        : u64 = BIT_U64!(31);
pub const LOG_SRV        : u64 = BIT_U64!(32);
pub const LOG_ATMA       : u64 = BIT_U64!(33);
pub const LOG_NAPTR      : u64 = BIT_U64!(34);
pub const LOG_KX         : u64 = BIT_U64!(35);
pub const LOG_CERT       : u64 = BIT_U64!(36);
pub const LOG_A6         : u64 = BIT_U64!(37);
pub const LOG_DNAME      : u64 = BIT_U64!(38);
pub const LOG_OPT        : u64 = BIT_U64!(39);
pub const LOG_APL        : u64 = BIT_U64!(40);
pub const LOG_DS         : u64 = BIT_U64!(41);
pub const LOG_SSHFP      : u64 = BIT_U64!(42);
pub const LOG_IPSECKEY   : u64 = BIT_U64!(43);
pub const LOG_RRSIG      : u64 = BIT_U64!(44);
pub const LOG_NSEC       : u64 = BIT_U64!(45);
pub const LOG_DNSKEY     : u64 = BIT_U64!(46);
pub const LOG_DHCID      : u64 = BIT_U64!(47);
pub const LOG_NSEC3      : u64 = BIT_U64!(48);
pub const LOG_NSEC3PARAM : u64 = BIT_U64!(49);
pub const LOG_TLSA       : u64 = BIT_U64!(50);
pub const LOG_HIP        : u64 = BIT_U64!(51);
pub const LOG_CDS        : u64 = BIT_U64!(52);
pub const LOG_CDNSKEY    : u64 = BIT_U64!(53);
pub const LOG_SPF        : u64 = BIT_U64!(54);
pub const LOG_TKEY       : u64 = BIT_U64!(55);
pub const LOG_TSIG       : u64 = BIT_U64!(56);
pub const LOG_MAILA      : u64 = BIT_U64!(57);
pub const LOG_ANY        : u64 = BIT_U64!(58);
pub const LOG_URI        : u64 = BIT_U64!(59);

fn dns_log_rrtype_enabled(rtype: u16, flags: u64) -> bool
{
    if flags == !0 {
        return true;
    }

    match rtype {
        DNS_RECORD_TYPE_A => {
            return flags & LOG_A != 0;
        }
        DNS_RECORD_TYPE_NS => {
            return flags & LOG_NS != 0;
        }
        DNS_RECORD_TYPE_MD => {
            return flags & LOG_MD != 0;
        }
        DNS_RECORD_TYPE_MF => {
            return flags & LOG_MF != 0;
        }
        DNS_RECORD_TYPE_CNAME => {
            return flags & LOG_CNAME != 0;
        }
        DNS_RECORD_TYPE_SOA => {
            return flags & LOG_SOA != 0;
        }
        DNS_RECORD_TYPE_MB => {
            return flags & LOG_MB != 0;
        }
        DNS_RECORD_TYPE_MG => {
            return flags & LOG_MG != 0;
        }
        DNS_RECORD_TYPE_MR => {
            return flags & LOG_MR != 0;
        }
        DNS_RECORD_TYPE_NULL => {
            return flags & LOG_NULL != 0;
        }
        DNS_RECORD_TYPE_WKS => {
            return flags & LOG_WKS != 0;
        }
        DNS_RECORD_TYPE_PTR => {
            return flags & LOG_PTR != 0;
        }
        DNS_RECORD_TYPE_HINFO => {
            return flags & LOG_HINFO != 0;
        }
        DNS_RECORD_TYPE_MINFO => {
            return flags & LOG_MINFO != 0;
        }
        DNS_RECORD_TYPE_MX => {
            return flags & LOG_MX != 0;
        }
        DNS_RECORD_TYPE_TXT => {
            return flags & LOG_TXT != 0;
        }
        DNS_RECORD_TYPE_RP => {
            return flags & LOG_RP != 0;
        }
        DNS_RECORD_TYPE_AFSDB => {
            return flags & LOG_AFSDB != 0;
        }
        DNS_RECORD_TYPE_X25 => {
            return flags & LOG_X25 != 0;
        }
        DNS_RECORD_TYPE_ISDN => {
            return flags & LOG_ISDN != 0;
        }
        DNS_RECORD_TYPE_RT => {
            return flags & LOG_RT != 0;
        }
        DNS_RECORD_TYPE_NSAP => {
            return flags & LOG_NSAP != 0;
        }
        DNS_RECORD_TYPE_NSAPPTR => {
            return flags & LOG_NSAPPTR != 0;
        }
        DNS_RECORD_TYPE_SIG => {
            return flags & LOG_SIG != 0;
        }
        DNS_RECORD_TYPE_KEY => {
            return flags & LOG_KEY != 0;
        }
        DNS_RECORD_TYPE_PX => {
            return flags & LOG_PX != 0;
        }
        DNS_RECORD_TYPE_GPOS => {
            return flags & LOG_GPOS != 0;
        }
        DNS_RECORD_TYPE_AAAA => {
            return flags & LOG_AAAA != 0;
        }
        DNS_RECORD_TYPE_LOC => {
            return flags & LOG_LOC != 0;
        }
        DNS_RECORD_TYPE_NXT => {
            return flags & LOG_NXT != 0;
        }
        DNS_RECORD_TYPE_SRV => {
            return flags & LOG_SRV != 0;
        }
        DNS_RECORD_TYPE_ATMA => {
            return flags & LOG_ATMA != 0;
        }
        DNS_RECORD_TYPE_NAPTR => {
            return flags & LOG_NAPTR != 0;
        }
        DNS_RECORD_TYPE_KX => {
            return flags & LOG_KX != 0;
        }
        DNS_RECORD_TYPE_CERT => {
            return flags & LOG_CERT != 0;
        }
        DNS_RECORD_TYPE_A6 => {
            return flags & LOG_A6 != 0;
        }
        DNS_RECORD_TYPE_DNAME => {
            return flags & LOG_DNAME != 0;
        }
        DNS_RECORD_TYPE_OPT => {
            return flags & LOG_OPT != 0;
        }
        DNS_RECORD_TYPE_APL => {
            return flags & LOG_APL != 0;
        }
        DNS_RECORD_TYPE_DS => {
            return flags & LOG_DS != 0;
        }
        DNS_RECORD_TYPE_SSHFP => {
            return flags & LOG_SSHFP != 0;
        }
        DNS_RECORD_TYPE_IPSECKEY => {
            return flags & LOG_IPSECKEY != 0;
        }
        DNS_RECORD_TYPE_RRSIG => {
            return flags & LOG_RRSIG != 0;
        }
        DNS_RECORD_TYPE_NSEC => {
            return flags & LOG_NSEC != 0;
        }
        DNS_RECORD_TYPE_DNSKEY => {
            return flags & LOG_DNSKEY != 0;
        }
        DNS_RECORD_TYPE_DHCID => {
            return flags & LOG_DHCID != 0;
        }
        DNS_RECORD_TYPE_NSEC3 => {
            return flags & LOG_NSEC3 != 0
        }
        DNS_RECORD_TYPE_NSEC3PARAM => {
            return flags & LOG_NSEC3PARAM != 0;
        }
        DNS_RECORD_TYPE_TLSA => {
            return flags & LOG_TLSA != 0;
        }
        DNS_RECORD_TYPE_HIP => {
            return flags & LOG_HIP != 0;
        }
        DNS_RECORD_TYPE_CDS => {
            return flags & LOG_CDS != 0;
        }
        DNS_RECORD_TYPE_CDNSKEY => {
            return flags & LOG_CDNSKEY != 0;
        }
        DNS_RECORD_TYPE_SPF => {
            return flags & LOG_SPF != 0;
        }
        DNS_RECORD_TYPE_TKEY => {
            return flags & LOG_TKEY != 0;
        }
        DNS_RECORD_TYPE_TSIG => {
            return flags & LOG_TSIG != 0;
        }
        DNS_RECORD_TYPE_MAILA => {
            return flags & LOG_MAILA != 0;
        }
        DNS_RECORD_TYPE_ANY => {
            return flags & LOG_ANY != 0;
        }
        DNS_RECORD_TYPE_URI => {
            return flags & LOG_URI != 0;
        }
        _ => {
            return false;
        }
    }
}

pub fn dns_rrtype_string(rrtype: u16) -> String {
    match rrtype {
        DNS_RTYPE_A => "A",
        DNS_RTYPE_CNAME => "CNAME",
        DNS_RTYPE_SOA => "SOA",
        DNS_RTYPE_PTR => "PTR",
        DNS_RTYPE_MX => "MX",
        DNS_RTYPE_AAAA => "AAAA",
        DNS_RTYPE_SSHFP => "SSHFP",
        DNS_RTYPE_RRSIG => "RRSIG",
        _ => {
            return rrtype.to_string();
        }
    }.to_string()
}

fn dns_rcode_string(flags: u16) -> String {
    match flags & 0x000f {
        DNS_RCODE_NOERROR => "NOERROR",
        DNS_RCODE_FORMERR => "FORMERR",
        DNS_RCODE_NXDOMAIN => "NXDOMAIN",
        _ => {
            return (flags & 0x000f).to_string();
        }
    }.to_string()
}

/// Format bytes as an IP address string.
pub fn dns_print_addr(addr: &Vec<u8>) -> std::string::String {
    if addr.len() == 4 {
        return format!("{}.{}.{}.{}", addr[0], addr[1], addr[2], addr[3]);
    }
    else if addr.len() == 16 {
        return format!("{:02x}{:02x}:{:02x}{:02x}:{:02x}{:02x}:{:02x}{:02x}:{:02x}{:02x}:{:02x}{:02x}:{:02x}{:02x}:{:02x}{:02x}",
                       addr[0],
                       addr[1],
                       addr[2],
                       addr[3],
                       addr[4],
                       addr[5],
                       addr[6],
                       addr[7],
                       addr[8],
                       addr[9],
                       addr[10],
                       addr[11],
                       addr[12],
                       addr[13],
                       addr[14],
                       addr[15]);
    }
    else {
        return "".to_string();
    }
}

///  Log the SSHPF in an DNSAnswerEntry.
fn dns_log_sshfp(js: &Json, answer: &DNSAnswerEntry)
{
    // Need at least 3 bytes - TODO: log something if we don't?
    if answer.data_len < 3 {
        return;
    }

    let sshfp = Json::object();

    let mut hex = Vec::new();
    for byte in &answer.data[2..] {
        hex.push(format!("{:02x}", byte));
    }
    sshfp.set_string("fingerprint", &hex.join(":"));
    sshfp.set_integer("algo", answer.data[0] as u64);
    sshfp.set_integer("type", answer.data[1] as u64);

    js.set("sshfp", sshfp);
}

#[no_mangle]
pub extern "C" fn rs_dns_log_json_query(tx: &mut DNSTransaction,
                                        i: libc::uint16_t,
                                        flags: libc::uint64_t)
                                        -> *mut JsonT
{
    let index = i as usize;
    for request in &tx.request {
        if index < request.queries.len() {
            let query = &request.queries[index];
            if dns_log_rrtype_enabled(query.rrtype, flags) {
                let js = Json::object();
                js.set_string("type", "query");
                js.set_integer("id", request.header.tx_id as u64);
                js.set_string("rrname", query.name());
                js.set_string("rrtype", &dns_rrtype_string(query.rrtype));
                js.set_integer("tx_id", tx.id - 1);
                return js.unwrap();
            }
        }
    }

    return std::ptr::null_mut();
}

fn dns_log_json_answer(header: &DNSHeader, answer: &DNSAnswerEntry)
                       -> Json
{
    let js = Json::object();

    js.set_string("type", "answer");
    js.set_integer("id", header.tx_id as u64);
    js.set_string("rcode", &dns_rcode_string(header.flags));
    js.set_string("rrname", answer.name());
    js.set_string("rrtype", &dns_rrtype_string(answer.rrtype));
    js.set_integer("ttl", answer.ttl as u64);

    match answer.rrtype {
        DNS_RTYPE_A | DNS_RTYPE_AAAA => {
            js.set_string("rdata", &dns_print_addr(&answer.data));
        }
        DNS_RTYPE_CNAME |
        DNS_RTYPE_MX |
        DNS_RTYPE_PTR => {
            js.set_string("rdata", answer.data_to_string());
        },
        DNS_RTYPE_SSHFP => {
            dns_log_sshfp(&js, &answer);
        },
        _ => {}
    }

    return js;
}

fn dns_log_json_failure(r: &DNSResponse, index: usize, flags: u64)
                        -> * mut JsonT {
    if index >= r.queries.len() {
        return std::ptr::null_mut();
    }

    let ref query = r.queries[index];

    if !dns_log_rrtype_enabled(query.rrtype, flags) {
        return std::ptr::null_mut();
    }

    let js = Json::object();

    js.set_string("type", "answer");
    js.set_integer("id", r.header.tx_id as u64);
    js.set_string("rcode", &dns_rcode_string(r.header.flags));
    js.set_string("rrname", std::str::from_utf8(&query.name[..]).unwrap());

    return js.unwrap();
}

#[no_mangle]
pub extern "C" fn rs_dns_log_json_answer(tx: &mut DNSTransaction,
                                         i: libc::uint16_t,
                                         flags: libc::uint64_t)
                                         -> *mut JsonT
{
    let index = i as usize;
    for response in &tx.response {
        if response.header.flags & 0x000f > 0 {
            if index == 0 {
                return dns_log_json_failure(response, index, flags);
            }
            break;
        }
        if index >= response.answers.len() {
            break;
        }
        let answer = &response.answers[index];
        if dns_log_rrtype_enabled(answer.rrtype, flags) {
            let js = dns_log_json_answer(&response.header, answer);
            return js.unwrap();
        }
    }
    return std::ptr::null_mut();
}

#[no_mangle]
pub extern "C" fn rs_dns_log_json_authority(tx: &mut DNSTransaction,
                                            i: libc::uint16_t,
                                            flags: libc::uint64_t)
                                            -> *mut JsonT
{
    let index = i as usize;
    for response in &tx.response {
        if index >= response.authorities.len() {
            break;
        }
        let answer = &response.authorities[index];
        if dns_log_rrtype_enabled(answer.rrtype, flags) {
            let js = dns_log_json_answer(&response.header, answer);
            return js.unwrap();
        }
    }
    return std::ptr::null_mut();
}