/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 *   Copyright 2018 (c) Kontron Europe GmbH (Author: Rudolf Hoyler)
 */

#include <open62541/plugin/log_stdout.h>
#include <open62541/plugin/pubsub_ethernet.h>
#include <open62541/util.h>

#include <linux/if_packet.h>
#include <netinet/ether.h>

#ifndef ETHERTYPE_UADP
#define ETHERTYPE_UADP 0xb62c
#endif

/* Ethernet network layer specific internal data */
typedef struct {
    int ifindex;
    UA_UInt16 vid;
    UA_Byte prio;
    UA_Byte ifAddress[ETH_ALEN];
    UA_Byte targetAddress[ETH_ALEN];
} UA_PubSubChannelDataEthernet;

/*
 * OPC-UA specification Part 14:
 *
 * "The target is a MAC address, an IP address or a registered name like a
 *  hostname. The format of a MAC address is six groups of hexadecimal digits,
 *  separated by hyphens (e.g. 01-23-45-67-89-ab). A system may also accept
 *  hostnames and/or IP addresses if it provides means to resolve it to a MAC
 *  address (e.g. DNS and Reverse-ARP)."
 *
 * We do not support currently IP addresses or hostnames.
 */
static UA_StatusCode
UA_parseHardwareAddress(UA_String* target, UA_Byte* destinationMac) {
    size_t curr = 0, idx = 0;
    for(; idx < ETH_ALEN; idx++) {
        UA_UInt32 value;
        size_t progress =
            UA_readNumberWithBase(&target->data[curr],
                                  target->length - curr, &value, 16);
        if(progress == 0 || value > (long)0xff)
            return UA_STATUSCODE_BADINTERNALERROR;

        destinationMac[idx] = (UA_Byte) value;

        curr += progress;
        if(curr == target->length)
            break;

        if(target->data[curr] != '-')
            return UA_STATUSCODE_BADINTERNALERROR;

        curr++; /* skip '-' */
    }

    if(idx != (ETH_ALEN-1))
        return UA_STATUSCODE_BADINTERNALERROR;

    return UA_STATUSCODE_GOOD;
}

/**
 * Open communication socket based on the connectionConfig.
 *
 * @return ref to created channel, NULL on error
 */
static UA_PubSubChannel *
UA_PubSubChannelEthernet_open(const UA_PubSubConnectionConfig *connectionConfig) {

    UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
                "Open PubSub ethernet connection.");

    /* allocate and init memory for the ethernet specific internal data */
    UA_PubSubChannelDataEthernet* channelDataEthernet =
            (UA_PubSubChannelDataEthernet*) UA_calloc(1, sizeof(*channelDataEthernet));
    if(!channelDataEthernet) {
        UA_LOG_ERROR (UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
            "PubSub Connection creation failed. Out of memory.");
        return NULL;
    }

    /* handle specified network address */
    UA_NetworkAddressUrlDataType *address;
    if(UA_Variant_hasScalarType(&connectionConfig->address,
                                 &UA_TYPES[UA_TYPES_NETWORKADDRESSURLDATATYPE])) {
        address = (UA_NetworkAddressUrlDataType *) connectionConfig->address.data;
    } else {
        UA_LOG_ERROR (UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
            "PubSub Connection creation failed. Invalid Address.");
        UA_free(channelDataEthernet);
        return NULL;
    }
    UA_LOG_DEBUG(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "Specified Interface Name = %.*s",
         (int) address->networkInterface.length, address->networkInterface.data);
    UA_LOG_DEBUG(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "Specified Network Url = %.*s",
         (int)address->url.length, address->url.data);

    UA_String target;
    /* encode the URL and store information in internal structure */
    if(UA_parseEndpointUrlEthernet(&address->url, &target, &channelDataEthernet->vid,
                                   &channelDataEthernet->prio)) {
        UA_LOG_ERROR (UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
            "PubSub Connection creation failed. Invalid Address URL.");
        UA_free(channelDataEthernet);
        return NULL;
    }

    /* Get a valid MAC address from target definition */
    if(UA_parseHardwareAddress(&target, channelDataEthernet->targetAddress) != UA_STATUSCODE_GOOD) {
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
                     "PubSub Connection creation failed. Invalid destination MAC address.");
        UA_free(channelDataEthernet);
        return NULL;
    }

    /* generate a new Pub/Sub channel and open a related socket */
    UA_PubSubChannel *newChannel = (UA_PubSubChannel*)UA_calloc(1, sizeof(UA_PubSubChannel));
    if(!newChannel) {
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
                     "PubSub Connection creation failed. Out of memory.");
        UA_free(channelDataEthernet);
        return NULL;
    }

    /* Open a packet socket */
    int sockFd = UA_socket(PF_PACKET, SOCK_RAW, 0);
    if(sockFd < 0) {
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
            "PubSub connection creation failed. Cannot create socket.");
        UA_free(channelDataEthernet);
        UA_free(newChannel);
        return NULL;
    }
    newChannel->sockfd = sockFd;

    /* allow the socket to be reused */
    int opt = 1;
    if(UA_setsockopt(sockFd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) < 0) {
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
            "PubSub connection creation failed. Cannot set socket reuse.");
        UA_close(sockFd);
        UA_free(channelDataEthernet);
        UA_free(newChannel);
        return NULL;
    }

    /* get interface index */
    struct ifreq ifreq;
    memset(&ifreq, 0, sizeof(struct ifreq));
    strncpy(ifreq.ifr_name, (char*)address->networkInterface.data,
            UA_MIN(address->networkInterface.length, sizeof(ifreq.ifr_name)-1));

    if(ioctl(sockFd, SIOCGIFINDEX, &ifreq) < 0) {
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
           "PubSub connection creation failed. Cannot get interface index.");
        UA_close(sockFd);
        UA_free(channelDataEthernet);
        UA_free(newChannel);
        return NULL;
    }
    channelDataEthernet->ifindex = ifreq.ifr_ifindex;

    /* determine own MAC address (source address for send) */
    if(ioctl(sockFd, SIOCGIFHWADDR, &ifreq) < 0) {
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
            "PubSub connection creation failed. Cannot determine own MAC address.");
        UA_close(sockFd);
        UA_free(channelDataEthernet);
        UA_free(newChannel);
        return NULL;
    }
    memcpy(channelDataEthernet->ifAddress, &ifreq.ifr_hwaddr.sa_data, ETH_ALEN);

    /* bind the socket to interface and ethertype */
    struct sockaddr_ll sll = { 0 };
    sll.sll_family = AF_PACKET;
    sll.sll_ifindex = channelDataEthernet->ifindex;
    sll.sll_protocol = htons(ETHERTYPE_UADP);

    if(UA_bind(sockFd, (struct sockaddr*)&sll, sizeof(sll)) < 0) {
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
            "PubSub connection creation failed. Cannot bind socket.");
        UA_close(sockFd);
        UA_free(channelDataEthernet);
        UA_free(newChannel);
        return NULL;
    }

    newChannel->handle = channelDataEthernet;
    newChannel->state = UA_PUBSUB_CHANNEL_PUB;

    return newChannel;
}

static UA_Boolean
is_multicast_address(const UA_Byte *address) {
    /* check if it is a unicast address */
    if((address[0] & 1) == 0) {
        return UA_FALSE;
    }

    /* and exclude broadcast addresses */
    for(size_t i = 0; i < ETH_ALEN; i++) {
        if(address[i] != 0xff)
            return UA_TRUE;
    }

    /* reaching this point, we know it has to be a broadcast address */
    return UA_FALSE;
}

/**
 * Subscribe to a given address.
 *
 * @return UA_STATUSCODE_GOOD on success
 */
static UA_StatusCode
UA_PubSubChannelEthernet_regist(UA_PubSubChannel *channel,
                                UA_ExtensionObject *transportSettings,
                                void (*notUsedHere)(UA_ByteString *encodedBuffer, UA_ByteString *topic)) {
    UA_PubSubChannelDataEthernet *channelDataEthernet =
        (UA_PubSubChannelDataEthernet *) channel->handle;

    if(!is_multicast_address(channelDataEthernet->targetAddress))
        return UA_STATUSCODE_GOOD;

    struct packet_mreq mreq;
    mreq.mr_ifindex = channelDataEthernet->ifindex;
    mreq.mr_type = PACKET_MR_MULTICAST;
    mreq.mr_alen = ETH_ALEN;
    memcpy(mreq.mr_address, channelDataEthernet->targetAddress, ETH_ALEN);

    if(UA_setsockopt(channel->sockfd, SOL_PACKET, PACKET_ADD_MEMBERSHIP, (char*) &mreq, sizeof(mreq)) < 0) {
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "PubSub Connection regist failed. %s", strerror(errno));
        return UA_STATUSCODE_BADINTERNALERROR;
    }

    return UA_STATUSCODE_GOOD;
}

/**
 * Remove current subscription.
 *
 * @return UA_STATUSCODE_GOOD on success
 */
static UA_StatusCode
UA_PubSubChannelEthernet_unregist(UA_PubSubChannel *channel,
                                  UA_ExtensionObject *transportSettings) {
    UA_PubSubChannelDataEthernet *channelDataEthernet =
        (UA_PubSubChannelDataEthernet *) channel->handle;

    if(!is_multicast_address(channelDataEthernet->targetAddress)) {
        return UA_STATUSCODE_GOOD;
    }

    struct packet_mreq mreq;
    mreq.mr_ifindex = channelDataEthernet->ifindex;
    mreq.mr_type = PACKET_MR_MULTICAST;
    mreq.mr_alen = ETH_ALEN;
    memcpy(mreq.mr_address, channelDataEthernet->targetAddress, ETH_ALEN);

    if(UA_setsockopt(channel->sockfd, SOL_PACKET, PACKET_DROP_MEMBERSHIP, (char*) &mreq, sizeof(mreq) < 0)) {
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "PubSub Connection regist failed.");
        return UA_STATUSCODE_BADINTERNALERROR;
    }

    return UA_STATUSCODE_GOOD;
}

/**
 * Send messages to the connection defined address
 *
 * @return UA_STATUSCODE_GOOD if success
 */
static UA_StatusCode
UA_PubSubChannelEthernet_send(UA_PubSubChannel *channel,
                              UA_ExtensionObject *transportSettings,
                              const UA_ByteString *buf) {
    UA_PubSubChannelDataEthernet *channelDataEthernet =
        (UA_PubSubChannelDataEthernet *) channel->handle;

    /* Allocate a buffer for the ethernet data which contains the ethernet
     * header (without VLAN tag), the VLAN tag and the OPC-UA/Ethernet data. */
    char *bufSend, *ptrCur;
    size_t lenBuf;
    struct ether_header* ethHdr;

    lenBuf = sizeof(*ethHdr) + 4 + buf->length;
    bufSend = (char*) UA_malloc(lenBuf);
    ethHdr = (struct ether_header*) bufSend;

    /* Set (own) source MAC address */
    memcpy(ethHdr->ether_shost, channelDataEthernet->ifAddress, ETH_ALEN);

    /* Set destination MAC address */
    memcpy(ethHdr->ether_dhost, channelDataEthernet->targetAddress, ETH_ALEN);

    /* Set ethertype */
    /* Either VLAN or Ethernet */
    ptrCur = bufSend + sizeof(*ethHdr);
    if(channelDataEthernet->vid == 0) {
        ethHdr->ether_type = htons(ETHERTYPE_UADP);
        lenBuf -= 4;  /* no VLAN tag */
    } else {
        ethHdr->ether_type = htons(ETHERTYPE_VLAN);
        /* set VLAN ID */
        UA_UInt16 vlanTag;
        vlanTag = (UA_UInt16) (channelDataEthernet->vid + (channelDataEthernet->prio << 13));
        *((UA_UInt16 *) ptrCur) = htons(vlanTag);
        ptrCur += sizeof(UA_UInt16);
        /* set Ethernet */
        *((UA_UInt16 *) ptrCur) = htons(ETHERTYPE_UADP);
        ptrCur += sizeof(UA_UInt16);
    }

    /* copy payload of ethernet message */
    memcpy(ptrCur, buf->data, buf->length);

    ssize_t rc;
    rc = UA_send(channel->sockfd, bufSend, lenBuf, 0);
    if(rc  < 0) {
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
            "PubSub connection send failed. Send message failed.");
        UA_free(bufSend);
        return UA_STATUSCODE_BADINTERNALERROR;
    }
    UA_free(bufSend);

    return UA_STATUSCODE_GOOD;
}

/**
 * Receive messages.
 *
 * @param timeout in usec -> not used
 * @return
 */
static UA_StatusCode
UA_PubSubChannelEthernet_receive(UA_PubSubChannel *channel, UA_ByteString *message,
                                 UA_ExtensionObject *transportSettings, UA_UInt32 timeout) {
    UA_PubSubChannelDataEthernet *channelDataEthernet =
        (UA_PubSubChannelDataEthernet *) channel->handle;

    struct ether_header eth_hdr;
    struct msghdr msg;
    struct iovec iov[2];

    iov[0].iov_base = &eth_hdr;
    iov[0].iov_len = sizeof(eth_hdr);
    iov[1].iov_base = message->data;
    iov[1].iov_len = message->length;
    msg.msg_namelen = 0;
    msg.msg_iov = iov;
    msg.msg_iovlen = 2;
    msg.msg_controllen = 0;

    /* Sleep in a select call if a timeout was set */
    if(timeout > 0) {
        fd_set fdset;
        FD_ZERO(&fdset);
        UA_fd_set(channel->sockfd, &fdset);
        struct timeval tmptv = {(long int)(timeout / 1000000),
                                (long int)(timeout % 1000000)};
        int resultsize = UA_select(channel->sockfd+1, &fdset, NULL, NULL, &tmptv);
        if(resultsize == 0) {
            message->length = 0;
            return UA_STATUSCODE_GOODNONCRITICALTIMEOUT;
        }
        if(resultsize == -1) {
            message->length = 0;
            return UA_STATUSCODE_BADINTERNALERROR;
        }
    }

    /* Read the current packet on the socket */
    ssize_t dataLen = recvmsg(channel->sockfd, &msg, 0);
    if(dataLen < 0) {
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
                     "PubSub connection receive failed. Receive message failed.");
        return UA_STATUSCODE_BADINTERNALERROR;
    }
    if((size_t)dataLen < sizeof(eth_hdr)) {
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
                     "PubSub connection receive failed. Packet too small.");
        return UA_STATUSCODE_BADINTERNALERROR;
    }
    if(dataLen == 0)
        return UA_STATUSCODE_GOODNODATA;

    /* Make sure we match our target */
    if(memcmp(eth_hdr.ether_dhost, channelDataEthernet->targetAddress, ETH_ALEN) != 0)
        return UA_STATUSCODE_GOODNODATA;

    /* Set the message length */
    message->length = (size_t)dataLen - sizeof(eth_hdr);

    return UA_STATUSCODE_GOOD;
}

/**
 * Close channel and free the channel data.
 *
 * @return UA_STATUSCODE_GOOD if success
 */
static UA_StatusCode
UA_PubSubChannelEthernet_close(UA_PubSubChannel *channel) {
    UA_close(channel->sockfd);
    UA_free(channel->handle);
    UA_free(channel);
    return UA_STATUSCODE_GOOD;
}

/**
 * Generate a new channel. based on the given configuration.
 *
 * @param connectionConfig connection configuration
 * @return  ref to created channel, NULL on error
 */
static UA_PubSubChannel *
TransportLayerEthernet_addChannel(UA_PubSubConnectionConfig *connectionConfig) {
    UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND, "PubSub channel requested");
    UA_PubSubChannel * pubSubChannel = UA_PubSubChannelEthernet_open(connectionConfig);
    if(pubSubChannel) {
        pubSubChannel->regist = UA_PubSubChannelEthernet_regist;
        pubSubChannel->unregist = UA_PubSubChannelEthernet_unregist;
        pubSubChannel->send = UA_PubSubChannelEthernet_send;
        pubSubChannel->receive = UA_PubSubChannelEthernet_receive;
        pubSubChannel->close = UA_PubSubChannelEthernet_close;
        pubSubChannel->connectionConfig = connectionConfig;
    }
    return pubSubChannel;
}

UA_PubSubTransportLayer
UA_PubSubTransportLayerEthernet() {
    UA_PubSubTransportLayer pubSubTransportLayer;
    pubSubTransportLayer.transportProfileUri =
        UA_STRING("http://opcfoundation.org/UA-Profile/Transport/pubsub-eth-uadp");
    pubSubTransportLayer.createPubSubChannel = &TransportLayerEthernet_addChannel;
    return pubSubTransportLayer;
}