/* vim: set expandtab ts=4 sw=4: */
/*
 * You may redistribute this program 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.
 *
 * 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
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#include "memory/Allocator.h"
#include "memory/MallocAllocator.h"
#include "interface/tuntap/TUNMessageType.h"
#include "util/log/Log.h"
#include "util/log/FileWriterLog.h"
#include "util/events/EventBase.h"
#include "crypto/random/Random.h"
#include "crypto/AddressCalc.h"
#include "tunnel/IpTunnel.h"
#include "util/Bits.h"
#include "util/Checksum.h"
#include "util/CString.h"
#include "wire/DataHeader.h"
#include "wire/Message.h"
#include "wire/Headers.h"
#include "wire/Ethernet.h"

static uint8_t* fakePubKey = (uint8_t*) "abcdefghijklmnopqrstuvwxyz012345";
static uint8_t nodeCjdnsIp6[16];
static uint8_t* fakeIp6ToGive = (uint8_t*) "\xfd\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1";
static int called = 0;

static Iface_DEFUN responseWithIpCallback(struct Message* message, struct Iface* iface)
{
    struct RouteHeader* rh = (struct RouteHeader*) message->bytes;
    Assert_true(!Bits_memcmp(nodeCjdnsIp6, rh->ip6, 16));
    Assert_true(!Bits_memcmp(fakePubKey, rh->publicKey, 32));

    Message_shift(message, -(RouteHeader_SIZE + DataHeader_SIZE), NULL);
    struct Headers_IP6Header* ip = (struct Headers_IP6Header*) message->bytes;
    Assert_true(Headers_getIpVersion(ip) == 6);
    uint16_t length = Endian_bigEndianToHost16(ip->payloadLength_be);
    Assert_true(length + Headers_IP6Header_SIZE == message->length);
    Assert_true(ip->nextHeader == 17);
    Assert_true(Bits_isZero(ip->sourceAddr, 32));

    Message_shift(message, -Headers_IP6Header_SIZE, NULL);
    struct Headers_UDPHeader* uh = (struct Headers_UDPHeader*) message->bytes;
    Assert_true(!Checksum_udpIp6(ip->sourceAddr, message->bytes, length));

    Assert_true(uh->srcPort_be == 0);
    Assert_true(uh->destPort_be == 0);
    Assert_true(Endian_bigEndianToHost16(uh->length_be) + Headers_UDPHeader_SIZE == length);

    Message_shift(message, -Headers_UDPHeader_SIZE, NULL);

    // We can't check that the message is an exact match because the padding depends on the
    // alignment of the output but we can make sure the right content is there...
    // Message should start with "d0000" (with some number of zeros)
    char* expectedResponse =
        "9:addresses" "d"
            "3:ip6" "16:\xfd\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1"
            "9:ip6Prefix" "i0e"
          "e"
          "4:txid" "4:abcd"
        "e";
    Assert_true(message->length >= (int32_t) CString_strlen(expectedResponse));
    Assert_true(CString_strstr(message->bytes, expectedResponse));
    called |= 2;
    return 0;
}

static Iface_DEFUN messageToTun(struct Message* message, struct Iface* iface)
{
    Assert_true(TUNMessageType_pop(message, NULL) == Ethernet_TYPE_IP6);
    struct Headers_IP6Header* ip = (struct Headers_IP6Header*) message->bytes;
    Assert_true(Headers_getIpVersion(ip) == 6);
    uint16_t length = Endian_bigEndianToHost16(ip->payloadLength_be);
    Assert_true(length + Headers_IP6Header_SIZE == message->length);
    Assert_true(ip->nextHeader == 17);
    Assert_true(!Bits_memcmp(ip->sourceAddr, fakeIp6ToGive, 16));
    called |= 1;
    return 0;
}

int main()
{
    AddressCalc_addressForPublicKey(nodeCjdnsIp6, fakePubKey);
    struct Allocator* alloc = MallocAllocator_new(1<<20);
    struct Log* logger = FileWriterLog_new(stdout, alloc);
    struct Random* rand = Random_new(alloc, logger, NULL);
    struct EventBase* eb = EventBase_new(alloc);

    struct IpTunnel* ipTun = IpTunnel_new(logger, eb, alloc, rand);
    struct Sockaddr_storage ip6ToGive;
    Sockaddr_parse("fd01:0101:0101:0101:0101:0101:0101:0101", &ip6ToGive);
    IpTunnel_allowConnection(fakePubKey, &ip6ToGive.addr, 0, NULL, 0, ipTun);

    struct Message* message;
    Message_STACK(message, 64, 512);
    message->alloc = alloc;

    const char* requestForAddresses =
        "d"
          "1:q" "21:IpTunnel_getAddresses"
          "4:txid" "4:abcd"
        "e";
    CString_strcpy((char*)message->bytes, requestForAddresses);
    message->length = CString_strlen(requestForAddresses);

    Message_shift(message, Headers_UDPHeader_SIZE, NULL);
    struct Headers_UDPHeader* uh = (struct Headers_UDPHeader*) message->bytes;

    uh->srcPort_be = 0;
    uh->destPort_be = 0;
    uh->length_be = Endian_hostToBigEndian16(message->length - Headers_UDPHeader_SIZE);
    uint16_t* checksum = &uh->checksum_be;
    *checksum = 0;
    uint32_t length = message->length;

    Message_shift(message, Headers_IP6Header_SIZE, NULL);
    struct Headers_IP6Header* ip = (struct Headers_IP6Header*) message->bytes;

    ip->versionClassAndFlowLabel = 0;
    ip->flowLabelLow_be = 0;
    ip->payloadLength_be = Endian_hostToBigEndian16(length);
    ip->nextHeader = 17;
    ip->hopLimit = 255;
    Bits_memset(ip->sourceAddr, 0, 32);
    Headers_setIpVersion(ip);

    Message_shift(message, RouteHeader_SIZE + DataHeader_SIZE, NULL);
    struct RouteHeader* rh = (struct RouteHeader*) message->bytes;
    struct DataHeader* dh = (struct DataHeader*) &rh[1];

    Bits_memset(rh, 0, RouteHeader_SIZE + DataHeader_SIZE);
    Bits_memcpyConst(rh->ip6, nodeCjdnsIp6, 16);
    Bits_memcpyConst(rh->publicKey, fakePubKey, 32);
    DataHeader_setContentType(dh, ContentType_IPTUN);

    *checksum = Checksum_udpIp6(ip->sourceAddr, (uint8_t*) uh, length);

    int origCap = message->capacity;
    int origLen = message->length;

    struct Iface nodeIface = { .send = responseWithIpCallback };
    Iface_plumb(&nodeIface, &ipTun->nodeInterface);
    struct Iface tunIface = { .send = messageToTun };
    Iface_plumb(&tunIface, &ipTun->tunInterface);

    Iface_send(&nodeIface, message);
    Assert_true(called == 2);
    called = 0;

    // This is a hack, reusing the message will cause breakage if IpTunnel is refactored.
    Message_reset(message);
    Message_shift(message, origCap, NULL);
    message->length = origLen;

    Bits_memcpyConst(ip->sourceAddr, fakeIp6ToGive, 16);
    // This can't be zero.
    Bits_memset(ip->destinationAddr, 1, 16);

    Iface_send(&nodeIface, message);
    Assert_true(called == 1);

    Allocator_free(alloc);
    return 0;
}