// Copyright (C) 2015 Internet Systems Consortium, Inc. ("ISC")
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
// OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
// PERFORMANCE OF THIS SOFTWARE.

#include <config.h>

#include <dhcp/dhcp4o6.h>
#include <dhcp/iface_mgr.h>
#include <dhcpsrv/dhcp4o6_ipc.h>

#include <netinet/in.h>
#include <string>

using namespace isc::asiolink;
using namespace isc::util;
using namespace std;

namespace isc {
namespace dhcp {

Dhcp4o6IpcBase::Dhcp4o6IpcBase() : port_(0), socket_fd_(-1) {}

Dhcp4o6IpcBase::~Dhcp4o6IpcBase() {
    close();
}

int Dhcp4o6IpcBase::open(uint16_t port, int side) {
    if (port == port_) {
        // No change: nothing to do
        return (socket_fd_);
    }

    // Port 0: closing
    if (port == 0) {
        port_ = 0;
        if (socket_fd_ != -1) {
            IfaceMgr::instance().deleteExternalSocket(socket_fd_);
            ::close(socket_fd_);
            socket_fd_ = -1;
        }
        return (socket_fd_);
    }

    // Open socket
    int sock = socket(PF_INET6, SOCK_DGRAM, IPPROTO_UDP);
    if (sock < 0) {
        isc_throw(Unexpected, "Failed to create DHCP4o6 socket.");
    }

    // Set reuse address
    int flag = 1;
    if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
                   (char *)&flag, sizeof(flag)) < 0) {
        ::close(sock);
        isc_throw(Unexpected, "Failed to set SO_REUSEADDR on DHCP4o6 socket.");
    }

    // Set no blocking
    if (fcntl(sock, F_SETFL, O_NONBLOCK) < 0) {
        ::close(sock);
        isc_throw(Unexpected, "Failed to set O_NONBLOCK on DHCP4o6 socket.");
    }

    // Bind to the local address
    struct sockaddr_in6 local6;
    memset(&local6, 0, sizeof(local6));
    local6.sin6_family = AF_INET6;
#ifdef HAVE_SA_LEN
    local6.sin6_len = sizeof(local6);
#endif
    if (side == 6) {
        local6.sin6_port = htons(port);
    } else {
        local6.sin6_port = htons(port + 1);
    }
    if (bind(sock, (struct sockaddr *)&local6, sizeof(local6)) < 0) {
        ::close(sock);
        isc_throw(Unexpected, "Failed to bind DHCP4o6 socket.");
    }

    // Connect to the remote address
    struct sockaddr_in6 remote6;
    memset(&remote6, 0, sizeof(remote6));
    remote6.sin6_family = AF_INET6;
#ifdef HAVE_SA_LEN
    remote6.sin6_len = sizeof(remote6);
#endif
    if (side == 6) {
        remote6.sin6_port = htons(port + 1);
    } else {
        remote6.sin6_port = htons(port);
    }
    if (connect(sock, (struct sockaddr *)&remote6, sizeof(remote6)) < 0) {
        ::close(sock);
        isc_throw(Unexpected, "Failed to connect DHCP4o6 socket.");
    }

    if (socket_fd_ != -1) {
        if (dup2(sock, socket_fd_) == -1) {
            ::close(sock);
            isc_throw(Unexpected, "Failed to duplicate DHCP4o6 socket.");
        }
        if (sock != socket_fd_) {
            ::close(sock);
            sock = socket_fd_;
        }
    }

    // Success
    port_ = port;
    socket_fd_ = sock;
    return (socket_fd_);
}

void Dhcp4o6IpcBase::close() {
    static_cast<void>(open(0, 0));
}

Pkt6Ptr Dhcp4o6IpcBase::receive() {
    uint8_t buf[65536];
    ssize_t cc = recv(socket_fd_, buf, sizeof(buf), 0);
    if (cc < 0) {
        isc_throw(Unexpected, "Failed to receive on DHCP4o6 socket.");
    }
    if (cc < DHCP4O6_DHCP6_OFFSET + Pkt6::DHCPV6_PKT_HDR_LEN) {
        // Ignore too short messages
        return (Pkt6Ptr());
    }
    char name[DHCP4O6_IFNAME_SIZE + 1];
    memcpy(name, buf, DHCP4O6_IFNAME_SIZE);
    IfacePtr iface = IfaceMgr::instance().getIface(string(name));
    if (!iface) {
        // Can't get the interface: ignore
        return (Pkt6Ptr());
    }
    uint8_t raddr[DHCP4O6_RADDR_SIZE];
    memcpy(raddr, buf + DHCP4O6_RADDR_OFFSET, DHCP4O6_RADDR_SIZE);
    IOAddress from = IOAddress::fromBytes(AF_INET6, raddr);
    Pkt6Ptr pkt;
    pkt = Pkt6Ptr(new Pkt6(buf + DHCP4O6_DHCP6_OFFSET,
                           cc - DHCP4O6_DHCP6_OFFSET));
    pkt->updateTimestamp();
    pkt->setRemoteAddr(from);
    pkt->setIface(iface->getName());
    pkt->setIndex(iface->getIndex());
    return (pkt);
}

void Dhcp4o6IpcBase::send(Pkt6Ptr pkt) {
    // No packet: nothing to send
    if (!pkt) {
        return;
    }

    // Disabled: nowhere to send
    if (socket_fd_ == -1) {
        return;
    }

    // Get interface name
    string name = pkt->getIface();
    if (name.empty() || name.size() > DHCP4O6_IFNAME_SIZE) {
        // Bad interface name: ignore
        return;
    }
    name.resize(DHCP4O6_IFNAME_SIZE);

    // Get remote address
    IOAddress from = pkt->getRemoteAddr();
    vector<uint8_t> raddr = from.toBytes();
    if (raddr.size() != DHCP4O6_RADDR_SIZE) {
        // Bad remote address: ignore
        return;
    }

    // Get packet content
    OutputBuffer& pbuf = pkt->getBuffer();
    if (!pbuf.getLength()) {
        // Empty buffer: content is not (yet) here, get it
        pkt->repack();
    }

    // Fill buffer
    vector<uint8_t> buf(DHCP4O6_DHCP6_OFFSET + pbuf.getLength());
    memcpy(&buf[0], name.c_str(), DHCP4O6_IFNAME_SIZE);
    memcpy(&buf[0] + DHCP4O6_RADDR_OFFSET, &raddr[0], DHCP4O6_RADDR_SIZE);
    memcpy(&buf[0] + DHCP4O6_DHCP6_OFFSET, pbuf.getData(), pbuf.getLength());

    // Send
    static_cast<void>(::send(socket_fd_, &buf[0], buf.size(), 0));
    return;
}

};  // namespace dhcp

};  // namespace isc