/*
 *  socket_linux.c
 *
 *  Copyright 2013-2018 Michael Zillgith
 *
 *  This file is part of libIEC61850.
 *
 *  libIEC61850 is free software: you can redistribute it 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.
 *
 *  libIEC61850 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 libIEC61850.  If not, see <http://www.gnu.org/licenses/>.
 *
 *  See COPYING file for the complete license text.
 */

#include "hal_socket.h"
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/select.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>
#include <netinet/in.h>
#include <netdb.h>
#include <errno.h>
#include <stdio.h>
#include <fcntl.h>
#include <netinet/tcp.h> // required for TCP keepalive

#include "hal_thread.h"
#include "lib_memory.h"

#ifndef DEBUG_SOCKET
#define DEBUG_SOCKET 0
#endif

struct sSocket {
    int fd;
    uint32_t connectTimeout;
};

struct sServerSocket {
    int fd;
    int backLog;
};

struct sHandleSet {
   fd_set handles;
   int maxHandle;
};

HandleSet
Handleset_new(void)
{
   HandleSet result = (HandleSet) GLOBAL_MALLOC(sizeof(struct sHandleSet));

   if (result != NULL) {
       FD_ZERO(&result->handles);
       result->maxHandle = -1;
   }
   return result;
}

void
Handleset_reset(HandleSet self)
{
    FD_ZERO(&self->handles);
    self->maxHandle = -1;
}

void
Handleset_addSocket(HandleSet self, const Socket sock)
{
   if (self != NULL && sock != NULL && sock->fd != -1) {
       FD_SET(sock->fd, &self->handles);
       if (sock->fd > self->maxHandle) {
           self->maxHandle = sock->fd;
       }
   }
}

int
Handleset_waitReady(HandleSet self, unsigned int timeoutMs)
{
   int result;

   if ((self != NULL) && (self->maxHandle >= 0)) {
       struct timeval timeout;

       timeout.tv_sec = timeoutMs / 1000;
       timeout.tv_usec = (timeoutMs % 1000) * 1000;
       result = select(self->maxHandle + 1, &self->handles, NULL, NULL, &timeout);
   } else {
       result = -1;
   }

   return result;
}

void
Handleset_destroy(HandleSet self)
{
   GLOBAL_FREEMEM(self);
}

void
Socket_activateTcpKeepAlive(Socket self, int idleTime, int interval, int count)
{
#if defined SO_KEEPALIVE
    int optval;
    socklen_t optlen = sizeof(optval);

    optval = 1;

    if (setsockopt(self->fd, SOL_SOCKET, SO_KEEPALIVE, &optval, optlen)) {
        if (DEBUG_SOCKET)
            printf("Failed to enable TCP keepalive\n");
    }

#if defined TCP_KEEPCNT
    optval = idleTime;
    if (setsockopt(self->fd, IPPROTO_TCP, TCP_KEEPIDLE, &optval, optlen)) {
        if (DEBUG_SOCKET)
            printf("Failed to set TCP keepalive TCP_KEEPIDLE parameter\n");
    }

    optval = interval;
    if (setsockopt(self->fd, IPPROTO_TCP, TCP_KEEPINTVL, &optval, optlen)) {
        if (DEBUG_SOCKET)
            printf("Failed to set TCP keepalive TCP_KEEPINTVL parameter\n");
    }

    optval = count;
    if (setsockopt(self->fd, IPPROTO_TCP, TCP_KEEPCNT, &optval, optlen)) {
        if (DEBUG_SOCKET)
            printf("Failed to set TCP keepalive TCP_KEEPCNT parameter\n");
    }
#endif /* TCP_KEEPCNT */

#endif /* SO_KEEPALIVE */
}

static bool
prepareServerAddress(const char* address, int port, struct sockaddr_in* sockaddr)
{
    bool retVal = true;

    memset((char *) sockaddr, 0, sizeof(struct sockaddr_in));

    if (address != NULL) {
        struct addrinfo addressHints;
        struct addrinfo *lookupResult;
        int result;

        memset(&addressHints, 0, sizeof(struct addrinfo));
        addressHints.ai_family = AF_INET;
        result = getaddrinfo(address, NULL, &addressHints, &lookupResult);

        if (result != 0) {
            retVal = false;
            goto exit_function;
        }

        memcpy(sockaddr, lookupResult->ai_addr, sizeof(struct sockaddr_in));
        freeaddrinfo(lookupResult);
    }
    else
        sockaddr->sin_addr.s_addr = htonl(INADDR_ANY);

    sockaddr->sin_family = AF_INET;
    sockaddr->sin_port = htons(port);

exit_function:
    return retVal;
}

static void
setSocketNonBlocking(Socket self)
{
    int flags = fcntl(self->fd, F_GETFL, 0);
    fcntl(self->fd, F_SETFL, flags | O_NONBLOCK);
}

static void
activateTcpNoDelay(Socket self)
{
    /* activate TCP_NODELAY option - packets will be sent immediately */
    int flag = 1;
    setsockopt(self->fd, IPPROTO_TCP, TCP_NODELAY, (char *) &flag, sizeof(int));
}

ServerSocket
TcpServerSocket_create(const char* address, int port)
{
    ServerSocket serverSocket = NULL;

    int fd;

    if ((fd = socket(AF_INET, SOCK_STREAM, 0)) >= 0) {
        struct sockaddr_in serverAddress;

        if (!prepareServerAddress(address, port, &serverAddress)) {
            close(fd);
            return NULL;
        }

        int optionReuseAddr = 1;
        setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, (char *) &optionReuseAddr, sizeof(int));

        if (bind(fd, (struct sockaddr *) &serverAddress, sizeof(serverAddress)) >= 0) {
            serverSocket = (ServerSocket) GLOBAL_MALLOC(sizeof(struct sServerSocket));
            serverSocket->fd = fd;
            serverSocket->backLog = 0;

            setSocketNonBlocking((Socket) serverSocket);
        }
        else {
            close(fd);
            return NULL ;
        }
    }

    return serverSocket;
}

void
ServerSocket_listen(ServerSocket self)
{
    listen(self->fd, self->backLog);
}


/* CHANGED TO MAKE NON-BLOCKING --> RETURNS NULL IF NO CONNECTION IS PENDING */
Socket
ServerSocket_accept(ServerSocket self)
{
    int fd;

    Socket conSocket = NULL;

    fd = accept(self->fd, NULL, NULL );

    if (fd >= 0) {
        conSocket = (Socket) GLOBAL_CALLOC(1, sizeof(struct sSocket));
        conSocket->fd = fd;

        activateTcpNoDelay(conSocket);
    }

    return conSocket;
}

void
ServerSocket_setBacklog(ServerSocket self, int backlog)
{
    self->backLog = backlog;
}

static void
closeAndShutdownSocket(int socketFd)
{
    if (socketFd != -1) {

        if (DEBUG_SOCKET)
            printf("socket_linux.c: call shutdown for %i!\n", socketFd);

        // shutdown is required to unblock read or accept in another thread!
        shutdown(socketFd, SHUT_RDWR);

        close(socketFd);
    }
}

void
ServerSocket_destroy(ServerSocket self)
{
    int fd = self->fd;

    self->fd = -1;

    closeAndShutdownSocket(fd);

    Thread_sleep(10);

    GLOBAL_FREEMEM(self);
}

Socket
TcpSocket_create()
{
    Socket self = NULL;

    int sock = socket(AF_INET, SOCK_STREAM, 0);

    if (sock != -1) {
        self = (Socket) GLOBAL_MALLOC(sizeof(struct sSocket));

        self->fd = sock;
        self->connectTimeout = 5000;
    }
    else {
        if (DEBUG_SOCKET)
            printf("SOCKET: failed to create socket (errno=%i)\n", errno);
    }

    return self;
}


void
Socket_setConnectTimeout(Socket self, uint32_t timeoutInMs)
{
    self->connectTimeout = timeoutInMs;
}


bool
Socket_connect(Socket self, const char* address, int port)
{
    struct sockaddr_in serverAddress;

    if (DEBUG_SOCKET)
        printf("SOCKET: connect: %s:%i\n", address, port);

    if (!prepareServerAddress(address, port, &serverAddress))
        return false;

    fd_set fdSet;
    FD_ZERO(&fdSet);
    FD_SET(self->fd, &fdSet);

    activateTcpNoDelay(self);

    fcntl(self->fd, F_SETFL, O_NONBLOCK);

    if (connect(self->fd, (struct sockaddr *) &serverAddress, sizeof(serverAddress)) < 0) {
        if (errno != EINPROGRESS)
            return false;
    }

    struct timeval timeout;
    timeout.tv_sec = self->connectTimeout / 1000;
    timeout.tv_usec = (self->connectTimeout % 1000) * 1000;

    if (select(self->fd + 1, NULL, &fdSet , NULL, &timeout) == 1) {
        int so_error;
        socklen_t len = sizeof so_error;

        getsockopt(self->fd, SOL_SOCKET, SO_ERROR, &so_error, &len);

        if (so_error == 0)
            return true;
    }

    close (self->fd);

    return false;
}

char*
Socket_getPeerAddress(Socket self)
{
    struct sockaddr_storage addr;
    socklen_t addrLen = sizeof(addr);

    getpeername(self->fd, (struct sockaddr*) &addr, &addrLen);

    char addrString[INET6_ADDRSTRLEN + 7];
    int port;

    bool isIPv6;

    if (addr.ss_family == AF_INET) {
        struct sockaddr_in* ipv4Addr = (struct sockaddr_in*) &addr;
        port = ntohs(ipv4Addr->sin_port);
        inet_ntop(AF_INET, &(ipv4Addr->sin_addr), addrString, INET_ADDRSTRLEN);
        isIPv6 = false;
    }
    else if (addr.ss_family == AF_INET6) {
        struct sockaddr_in6* ipv6Addr = (struct sockaddr_in6*) &addr;
        port = ntohs(ipv6Addr->sin6_port);
        inet_ntop(AF_INET6, &(ipv6Addr->sin6_addr), addrString, INET6_ADDRSTRLEN);
        isIPv6 = true;
    }
    else
        return NULL ;

    char* clientConnection = (char*) GLOBAL_MALLOC(strlen(addrString) + 9);


    if (isIPv6)
        sprintf(clientConnection, "[%s]:%i", addrString, port);
    else
        sprintf(clientConnection, "%s:%i", addrString, port);

    return clientConnection;
}

char*
Socket_getPeerAddressStatic(Socket self, char* peerAddressString)
{
    struct sockaddr_storage addr;
    socklen_t addrLen = sizeof(addr);

    getpeername(self->fd, (struct sockaddr*) &addr, &addrLen);

    char addrString[INET6_ADDRSTRLEN + 7];
    int port;

    bool isIPv6;

    if (addr.ss_family == AF_INET) {
        struct sockaddr_in* ipv4Addr = (struct sockaddr_in*) &addr;
        port = ntohs(ipv4Addr->sin_port);
        inet_ntop(AF_INET, &(ipv4Addr->sin_addr), addrString, INET_ADDRSTRLEN);
        isIPv6 = false;
    }
    else if (addr.ss_family == AF_INET6) {
        struct sockaddr_in6* ipv6Addr = (struct sockaddr_in6*) &addr;
        port = ntohs(ipv6Addr->sin6_port);
        inet_ntop(AF_INET6, &(ipv6Addr->sin6_addr), addrString, INET6_ADDRSTRLEN);
        isIPv6 = true;
    }
    else
        return NULL ;

    if (isIPv6)
        sprintf(peerAddressString, "[%s]:%i", addrString, port);
    else
        sprintf(peerAddressString, "%s:%i", addrString, port);

    return peerAddressString;
}

int
Socket_read(Socket self, uint8_t* buf, int size)
{
    if (self->fd == -1)
        return -1;

    int read_bytes = recv(self->fd, buf, size, MSG_DONTWAIT);

    if (read_bytes == 0)
        return -1;

    if (read_bytes == -1) {
        int error = errno;

        switch (error) {

            case EAGAIN:
                return 0;
            case EBADF:
                return -1;

            default:
                return -1;
        }
    }

    return read_bytes;
}

int
Socket_write(Socket self, uint8_t* buf, int size)
{
    if (self->fd == -1)
        return -1;

    // MSG_NOSIGNAL - prevent send to signal SIGPIPE when peer unexpectedly closed the socket
    return send(self->fd, buf, size, MSG_NOSIGNAL);
}

void
Socket_destroy(Socket self)
{
    int fd = self->fd;

    self->fd = -1;

    closeAndShutdownSocket(fd);

    Thread_sleep(10);

    GLOBAL_FREEMEM(self);
}