/*
 * This work is licensed under a Creative Commons CCZero 1.0 Universal License.
 * See http://creativecommons.org/publicdomain/zero/1.0/ for more information.
 */

#include "networklayer_tcp.h"

#include <stdlib.h> // malloc, free
#include <string.h> // memset
#include <errno.h>

#ifdef _WIN32
# include <malloc.h>
# include <winsock2.h>
# include <ws2tcpip.h>
# define CLOSESOCKET(S) closesocket(S)
#else
# include <fcntl.h>
# include <sys/select.h>
# include <netinet/in.h>
#ifndef __CYGWIN__
    # include <netinet/tcp.h>
#endif
# include <sys/ioctl.h>
# include <netdb.h> //gethostbyname for the client
# include <unistd.h> // read, write, close
# include <arpa/inet.h>
#ifdef __QNX__
#include <sys/socket.h>
#endif
# define CLOSESOCKET(S) close(S)
#endif

#ifdef UA_MULTITHREADING
# include <urcu/uatomic.h>
#endif

#ifndef MSG_NOSIGNAL
#define MSG_NOSIGNAL 0
#endif

/****************************/
/* Generic Socket Functions */
/****************************/

static void socket_close(UA_Connection *connection) {
    connection->state = UA_CONNECTION_CLOSED;
    shutdown(connection->sockfd,2);
    CLOSESOCKET(connection->sockfd);
}

static UA_StatusCode socket_write(UA_Connection *connection, UA_ByteString *buf) {
    size_t nWritten = 0;
    while(buf->length > 0 && nWritten < (size_t)buf->length) {
        UA_Int32 n = 0;
        do {
#ifdef _WIN32
            n = send((SOCKET)connection->sockfd, (const char*)buf->data, (size_t)buf->length, 0);
            const int last_error = WSAGetLastError();
            if(n < 0 && last_error != WSAEINTR && last_error != WSAEWOULDBLOCK) {
                connection->close(connection);
                socket_close(connection);
#ifdef UA_MULTITHREADING
                UA_ByteString_deleteMembers(buf);
#endif
                return UA_STATUSCODE_BADCONNECTIONCLOSED;
            }
#else
            n = send(connection->sockfd, (const char*)buf->data, (size_t)buf->length, MSG_NOSIGNAL);
            if(n == -1L && errno != EINTR && errno != EAGAIN) {
                connection->close(connection);
                socket_close(connection);
#ifdef UA_MULTITHREADING
                UA_ByteString_deleteMembers(buf);
#endif
                return UA_STATUSCODE_BADCONNECTIONCLOSED;
            }
#endif
        } while (n == -1L);
        nWritten += n;
    }
#ifdef UA_MULTITHREADING
    UA_ByteString_deleteMembers(buf);
#endif
    return UA_STATUSCODE_GOOD;
}

static UA_StatusCode socket_recv(UA_Connection *connection, UA_ByteString *response, UA_UInt32 timeout) {
    response->data = malloc(connection->localConf.recvBufferSize);
    if(!response->data) {
        response->length = -1;
        return UA_STATUSCODE_GOOD; /* not enough memory retry */
    }

    struct timeval tmptv = {0, timeout * 1000};
    if(0 != setsockopt(connection->sockfd, SOL_SOCKET, SO_RCVTIMEO, (char *)&tmptv, sizeof(struct timeval))) {
        UA_ByteString_deleteMembers(response);
        socket_close(connection);
        return UA_STATUSCODE_BADINTERNALERROR;
    }

    int ret = recv(connection->sockfd, (char*)response->data, connection->localConf.recvBufferSize, 0);
	if(ret == 0) {
		free(response->data);
        UA_ByteString_init(response);
        socket_close(connection);
        return UA_STATUSCODE_BADCONNECTIONCLOSED; /* ret == 0 -> server has closed the connection */
	} else if(ret < 0) {
        free(response->data);
        UA_ByteString_init(response);
#ifdef _WIN32
        const int last_error = WSAGetLastError();
        if(last_error == WSAEINTR || last_error == WSAEWOULDBLOCK)
#else
		if(errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK)
#endif
            return UA_STATUSCODE_GOOD; /* retry */
        else {
            socket_close(connection);
            return UA_STATUSCODE_BADCONNECTIONCLOSED;
        }
    }
    response->length = ret;
    return UA_STATUSCODE_GOOD;
}

static UA_StatusCode socket_set_nonblocking(UA_Int32 sockfd) {
#ifdef _WIN32
    u_long iMode = 1;
    if(ioctlsocket(sockfd, FIONBIO, &iMode) != NO_ERROR)
        return UA_STATUSCODE_BADINTERNALERROR;
#else
    int opts = fcntl(sockfd, F_GETFL);
    if(opts < 0 || fcntl(sockfd, F_SETFL, opts|O_NONBLOCK) < 0)
        return UA_STATUSCODE_BADINTERNALERROR;
#endif
    return UA_STATUSCODE_GOOD;
}

static void FreeConnectionCallback(UA_Server *server, void *ptr) {
    UA_Connection_deleteMembers((UA_Connection*)ptr);
     free(ptr);
 }

/***************************/
/* Server NetworkLayer TCP */
/***************************/

/**
 * For the multithreaded mode, assume a single thread that periodically "gets work" from the network
 * layer. In addition, several worker threads are asynchronously calling into the callbacks of the
 * UA_Connection that holds a single connection.
 *
 * Creating a connection: When "GetWork" encounters a new connection, it creates a UA_Connection
 * with the socket information. This is added to the mappings array that links sockets to
 * UA_Connection structs.
 *
 * Reading data: In "GetWork", we listen on the sockets in the mappings array. If data arrives (or
 * the connection closes), a WorkItem is created that carries the work and a pointer to the
 * connection.
 *
 * Closing a connection: Closing can happen in two ways. Either it is triggered by the server in an
 * asynchronous callback. Or the connection is close by the client and this is detected in
 * "GetWork". The server needs to do some internal cleanups (close attached securechannels, etc.).
 * So even when a closed connection is detected in "GetWork", we trigger the server to close the
 * connection (with a WorkItem) and continue from the callback.
 *
 * - Server calls close-callback: We close the socket, set the connection-state to closed and add
 *   the connection to a linked list from which it is deleted later. The connection cannot be freed
 *   right away since other threads might still be using it.
 *
 * - GetWork: We remove the connection from the mappings array. In the non-multithreaded case, the
 *   connection is freed. For multithreading, we return a workitem that is delayed, i.e. that is
 *   called only after all workitems created before are finished in all threads. This workitems
 *   contains a callback that goes through the linked list of connections to be freed.
 *
 */

#define MAXBACKLOG 100

typedef struct {
    UA_ServerNetworkLayer layer;
    
    /* config */
    UA_UInt32 port;
    UA_ConnectionConfig conf; /* todo: rename to localconf. */

#ifndef UA_MULTITHREADING
    UA_ByteString buffer; // message buffer that is reused
#endif

    /* open sockets and connections */
    fd_set fdset;
    UA_Int32 serversockfd;
    UA_Int32 highestfd;
    size_t mappingsSize;
    struct ConnectionMapping {
        UA_Connection *connection;
        UA_Int32 sockfd;
    } *mappings;
} ServerNetworkLayerTCP;

static UA_StatusCode ServerNetworkLayerGetSendBuffer(UA_Connection *connection, UA_Int32 length, UA_ByteString *buf) {
    if((UA_UInt32)length > connection->remoteConf.recvBufferSize)
        return UA_STATUSCODE_BADCOMMUNICATIONERROR;
#ifdef UA_MULTITHREADING
    return UA_ByteString_newMembers(buf, length);
#else
    ServerNetworkLayerTCP *layer = connection->handle;
    *buf = layer->buffer;
    return UA_STATUSCODE_GOOD;
#endif
}

static void ServerNetworkLayerReleaseSendBuffer(UA_Connection *connection, UA_ByteString *buf) {
#ifdef UA_MULTITHREADING
    UA_ByteString_deleteMembers(buf);
#endif
}

static void ServerNetworkLayerReleaseRecvBuffer(UA_Connection *connection, UA_ByteString *buf) {
    UA_ByteString_deleteMembers(buf);
}

/* after every select, we need to reset the sockets we want to listen on */
static void setFDSet(ServerNetworkLayerTCP *layer) {
    FD_ZERO(&layer->fdset);
    FD_SET((UA_UInt32)layer->serversockfd, &layer->fdset);
    layer->highestfd = layer->serversockfd;
    for(size_t i = 0; i < layer->mappingsSize; i++) {
        FD_SET((UA_UInt32)layer->mappings[i].sockfd, &layer->fdset);
        if(layer->mappings[i].sockfd > layer->highestfd)
            layer->highestfd = layer->mappings[i].sockfd;
    }
}

/* callback triggered from the server */
static void ServerNetworkLayerTCP_closeConnection(UA_Connection *connection) {
#ifdef UA_MULTITHREADING
    if(uatomic_xchg(&connection->state, UA_CONNECTION_CLOSED) == UA_CONNECTION_CLOSED)
        return;
#else
    if(connection->state == UA_CONNECTION_CLOSED)
        return;
    connection->state = UA_CONNECTION_CLOSED;
#endif
    shutdown(connection->sockfd, 2); /* only shut down here. this triggers the select, where the socket
                                        is closed in the main thread */
}

/* call only from the single networking thread */
static UA_StatusCode ServerNetworkLayerTCP_add(ServerNetworkLayerTCP *layer, UA_Int32 newsockfd) {
    UA_Connection *c = malloc(sizeof(UA_Connection));
    if(!c)
        return UA_STATUSCODE_BADINTERNALERROR;
    UA_Connection_init(c);
    c->sockfd = newsockfd;
    c->handle = layer;
    c->localConf = layer->conf;
    c->send = socket_write;
    c->close = ServerNetworkLayerTCP_closeConnection;
    c->getSendBuffer = ServerNetworkLayerGetSendBuffer;
    c->releaseSendBuffer = ServerNetworkLayerReleaseSendBuffer;
    c->releaseRecvBuffer = ServerNetworkLayerReleaseRecvBuffer;
    c->state = UA_CONNECTION_OPENING;
    struct ConnectionMapping *nm;
    nm = realloc(layer->mappings, sizeof(struct ConnectionMapping)*(layer->mappingsSize+1));
    if(!nm) {
        free(c);
        return UA_STATUSCODE_BADINTERNALERROR;
    }
    layer->mappings = nm;
    layer->mappings[layer->mappingsSize] = (struct ConnectionMapping){c, newsockfd};
    layer->mappingsSize++;
    return UA_STATUSCODE_GOOD;
}

static UA_StatusCode ServerNetworkLayerTCP_start(ServerNetworkLayerTCP *layer, UA_Logger logger) {
    layer->layer.logger = logger;
#ifdef _WIN32
    if((layer->serversockfd = socket(PF_INET, SOCK_STREAM,0)) == (UA_Int32)INVALID_SOCKET) {
        UA_LOG_WARNING(layer->layer.logger, UA_LOGCATEGORY_COMMUNICATION, "Error opening socket, code: %d",
                       WSAGetLastError());
        return UA_STATUSCODE_BADINTERNALERROR;
    }
#else
    if((layer->serversockfd = socket(PF_INET, SOCK_STREAM, 0)) < 0) {
        UA_LOG_WARNING(layer->layer.logger, UA_LOGCATEGORY_COMMUNICATION, "Error opening socket");
        return UA_STATUSCODE_BADINTERNALERROR;
    }
#endif
    const struct sockaddr_in serv_addr =
        {.sin_family = AF_INET, .sin_addr.s_addr = INADDR_ANY,
         .sin_port = htons(layer->port), .sin_zero = {0}};
    int optval = 1;
    if(setsockopt(layer->serversockfd, SOL_SOCKET,
                  SO_REUSEADDR, (const char *)&optval,
                  sizeof(optval)) == -1) {
        UA_LOG_WARNING(layer->layer.logger, UA_LOGCATEGORY_COMMUNICATION,
                       "Error during setting of socket options");
        CLOSESOCKET(layer->serversockfd);
        return UA_STATUSCODE_BADINTERNALERROR;
    }
    if(bind(layer->serversockfd, (const struct sockaddr *)&serv_addr,
            sizeof(serv_addr)) < 0) {
        UA_LOG_WARNING(layer->layer.logger, UA_LOGCATEGORY_COMMUNICATION, "Error during socket binding");
        CLOSESOCKET(layer->serversockfd);
        return UA_STATUSCODE_BADINTERNALERROR;
    }
    socket_set_nonblocking(layer->serversockfd);
    listen(layer->serversockfd, MAXBACKLOG);
    UA_LOG_INFO(layer->layer.logger, UA_LOGCATEGORY_COMMUNICATION, "Listening on %.*s",
                layer->layer.discoveryUrl.length, layer->layer.discoveryUrl.data);
    return UA_STATUSCODE_GOOD;
}

static size_t ServerNetworkLayerTCP_getJobs(ServerNetworkLayerTCP *layer, UA_Job **jobs, UA_UInt16 timeout) {
    setFDSet(layer);
    struct timeval tmptv = {0, timeout};
    UA_Int32 resultsize;
 repeat_select:
    resultsize = select(layer->highestfd+1, &layer->fdset, NULL, NULL, &tmptv);
    if(resultsize < 0) {
        if(errno == EINTR)
            goto repeat_select;
        *jobs = NULL;
        return 0;
    }

    /* accept new connections (can only be a single one) */
    if(FD_ISSET(layer->serversockfd, &layer->fdset)) {
        resultsize--;
        struct sockaddr_in cli_addr;
        socklen_t cli_len = sizeof(cli_addr);
        int newsockfd = accept(layer->serversockfd, (struct sockaddr *) &cli_addr, &cli_len);
        int i = 1;
        setsockopt(newsockfd, IPPROTO_TCP, TCP_NODELAY, (void *)&i, sizeof(i));
        if(newsockfd >= 0) {
            socket_set_nonblocking(newsockfd);
            ServerNetworkLayerTCP_add(layer, newsockfd);
        }
    }

    /* alloc enough space for a cleanup-connection and free-connection job per resulted socket */
    if(resultsize == 0)
        return 0;
    UA_Job *js = malloc(sizeof(UA_Job) * resultsize * 2);
    if(!js)
        return 0;

    /* read from established sockets */
    size_t j = 0;
    UA_ByteString buf = UA_BYTESTRING_NULL;
    for(size_t i = 0; i < layer->mappingsSize && j < (size_t)resultsize; i++) {
        if(!(FD_ISSET(layer->mappings[i].sockfd, &layer->fdset)))
            continue;
        if(socket_recv(layer->mappings[i].connection, &buf, 0) == UA_STATUSCODE_GOOD) {
            if(!buf.data)
                continue;
            js[j] = UA_Connection_completeMessages(layer->mappings[i].connection, buf);
        } else {
            UA_Connection *c = layer->mappings[i].connection;
            /* the socket is already closed */
            js[j].type = UA_JOBTYPE_DETACHCONNECTION;
            js[j].job.closeConnection = layer->mappings[i].connection;
            layer->mappings[i] = layer->mappings[layer->mappingsSize-1];
            layer->mappingsSize--;
            j++;
            i--; // iterate over the same index again
            js[j].type = UA_JOBTYPE_METHODCALL_DELAYED;
            js[j].job.methodCall.method = FreeConnectionCallback;
            js[j].job.methodCall.data = c;
        }
        j++;
    }

    if(j == 0) {
    	free(js);
    	js = NULL;
    }

    *jobs = js;
    return j;
}

static size_t ServerNetworkLayerTCP_stop(ServerNetworkLayerTCP *layer, UA_Job **jobs) {
    UA_Job *items = malloc(sizeof(UA_Job) * layer->mappingsSize * 2);
    if(!items)
        return 0;
    for(size_t i = 0; i < layer->mappingsSize; i++) {
        socket_close(layer->mappings[i].connection);
        items[i*2].type = UA_JOBTYPE_DETACHCONNECTION;
        items[i*2].job.closeConnection = layer->mappings[i].connection;
        items[(i*2)+1].type = UA_JOBTYPE_METHODCALL_DELAYED;
        items[(i*2)+1].job.methodCall.method = FreeConnectionCallback;
        items[(i*2)+1].job.methodCall.data = layer->mappings[i].connection;
    }
#ifdef _WIN32
    WSACleanup();
#endif
    *jobs = items;
    return layer->mappingsSize*2;
}

/* run only when the server is stopped */
static void ServerNetworkLayerTCP_deleteMembers(ServerNetworkLayerTCP *layer) {
#ifndef UA_MULTITHREADING
    UA_ByteString_deleteMembers(&layer->buffer);
#endif
    for(size_t i = 0; i < layer->mappingsSize; i++)
        free(layer->mappings[i].connection);
    free(layer->mappings);
}

UA_ServerNetworkLayer * ServerNetworkLayerTCP_new(UA_ConnectionConfig conf, UA_UInt32 port) {
#ifdef _WIN32
    WORD wVersionRequested;
    WSADATA wsaData;
    wVersionRequested = MAKEWORD(2, 2);
    WSAStartup(wVersionRequested, &wsaData);
#endif
    ServerNetworkLayerTCP *layer = malloc(sizeof(ServerNetworkLayerTCP));
    if(!layer)
        return NULL;
    memset(layer, 0, sizeof(ServerNetworkLayerTCP));
    layer->conf = conf;
    layer->mappingsSize = 0;
    layer->mappings = NULL;
    layer->port = port;
    char hostname[256];
    gethostname(hostname, 255);
    UA_String_copyprintf("opc.tcp://%s:%d", &layer->layer.discoveryUrl, hostname, port);

#ifndef UA_MULTITHREADING
    layer->buffer = (UA_ByteString){.length = conf.maxMessageSize, .data = malloc(conf.maxMessageSize)};
#endif

    layer->layer.start = (UA_StatusCode(*)(UA_ServerNetworkLayer*,UA_Logger))ServerNetworkLayerTCP_start;
    layer->layer.getJobs = (size_t(*)(UA_ServerNetworkLayer*,UA_Job**,UA_UInt16))ServerNetworkLayerTCP_getJobs;
    layer->layer.stop = (size_t(*)(UA_ServerNetworkLayer*, UA_Job**))ServerNetworkLayerTCP_stop;
    layer->layer.deleteMembers = (void(*)(UA_ServerNetworkLayer*))ServerNetworkLayerTCP_deleteMembers;
    return &layer->layer;
}

/***************************/
/* Client NetworkLayer TCP */
/***************************/

static UA_StatusCode ClientNetworkLayerGetBuffer(UA_Connection *connection, UA_Int32 length, UA_ByteString *buf) {
    if((UA_UInt32)length > connection->remoteConf.recvBufferSize)
        return UA_STATUSCODE_BADCOMMUNICATIONERROR;
#ifndef UA_MULTITHREADING
    if(connection->state == UA_CONNECTION_CLOSED)
        return UA_STATUSCODE_BADCONNECTIONCLOSED;
    *buf = *(UA_ByteString*)connection->handle;
    return UA_STATUSCODE_GOOD;
#else
    return UA_ByteString_newMembers(buf, connection->remoteConf.recvBufferSize);
#endif
}

static void ClientNetworkLayerReleaseBuffer(UA_Connection *connection, UA_ByteString *buf) {
#ifdef UA_MULTITHREADING
    UA_ByteString_deleteMembers(buf);
#endif
}

static void ClientNetworkLayerClose(UA_Connection *connection) {
#ifndef UA_MULTITHREADING
    if(connection->handle)
        UA_ByteString_delete(connection->handle);
    connection->handle = NULL;
#endif
    if(connection->state == UA_CONNECTION_CLOSED)
        return;
    connection->state = UA_CONNECTION_CLOSED;
    socket_close(connection);
}

/* we have no networklayer. instead, attach the reusable buffer to the handle */
UA_Connection
ClientNetworkLayerTCP_connect(UA_ConnectionConfig localConf, char *endpointUrl, UA_Logger logger) {
    UA_Connection connection;
    UA_Connection_init(&connection);
    connection.localConf = localConf;
#ifndef UA_MULTITHREADING
    connection.handle = UA_ByteString_new();
    UA_ByteString_newMembers(connection.handle, localConf.maxMessageSize);
#endif

    size_t urlLength = strlen(endpointUrl);
    if(urlLength < 11 || urlLength >= 512) {
        UA_LOG_WARNING((*logger), UA_LOGCATEGORY_COMMUNICATION, "Server url size invalid");
        return connection;
    }
    if(strncmp(endpointUrl, "opc.tcp://", 10) != 0) {
        UA_LOG_WARNING((*logger), UA_LOGCATEGORY_COMMUNICATION, "Server url does not begin with opc.tcp://");
        return connection;
    }

    UA_UInt16 portpos = 9;
    UA_UInt16 port;
    for(port = 0; portpos < urlLength-1; portpos++) {
        if(endpointUrl[portpos] == ':') {
            port = atoi(&endpointUrl[portpos+1]);
            break;
        }
    }
    if(port == 0) {
        UA_LOG_WARNING((*logger), UA_LOGCATEGORY_COMMUNICATION, "Port invalid");
        return connection;
    }

    char hostname[512];
    for(int i=10; i < portpos; i++)
        hostname[i-10] = endpointUrl[i];
    hostname[portpos-10] = 0;
#ifdef _WIN32
    WORD wVersionRequested;
    WSADATA wsaData;
    wVersionRequested = MAKEWORD(2, 2);
    WSAStartup(wVersionRequested, &wsaData);
    if((connection.sockfd = socket(PF_INET, SOCK_STREAM,0)) == (UA_Int32)INVALID_SOCKET) {
#else
    if((connection.sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
#endif
        UA_LOG_WARNING((*logger), UA_LOGCATEGORY_COMMUNICATION, "Could not create socket");
        return connection;
    }
    struct hostent *server = gethostbyname(hostname);
    if(!server) {
        UA_LOG_WARNING((*logger), UA_LOGCATEGORY_COMMUNICATION, "DNS lookup of %s failed", hostname);
        return connection;
    }
    struct sockaddr_in server_addr;
    memset(&server_addr, 0, sizeof(server_addr));
    memcpy((char *)&server_addr.sin_addr.s_addr, (char *)server->h_addr_list[0], server->h_length);
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(port);
    connection.state = UA_CONNECTION_OPENING;
    if(connect(connection.sockfd, (struct sockaddr *) &server_addr, sizeof(server_addr)) < 0) {
        ClientNetworkLayerClose(&connection);
        UA_LOG_WARNING((*logger), UA_LOGCATEGORY_COMMUNICATION, "Connection failed");
        return connection;
    }

#ifdef SO_NOSIGPIPE
    int val = 1;
    if(setsockopt(connection.sockfd, SOL_SOCKET, SO_NOSIGPIPE, (void*)&val, sizeof(val)) < 0) {
        UA_LOG_WARNING((*logger), UA_LOGCATEGORY_COMMUNICATION, "Couldn't set SO_NOSIGPIPE");
        return connection;
    }
#endif

    //socket_set_nonblocking(connection.sockfd);
    connection.send = socket_write;
    connection.recv = socket_recv;
    connection.close = ClientNetworkLayerClose;
    connection.getSendBuffer = ClientNetworkLayerGetBuffer;
    connection.releaseSendBuffer = ClientNetworkLayerReleaseBuffer;
    connection.releaseRecvBuffer = ClientNetworkLayerReleaseBuffer;
    return connection;
}