/* sharkd_daemon.c
 *
 * Copyright (C) 2016 Jakub Zawadzki
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

#include <config.h>
#define WS_LOG_DOMAIN LOG_DOMAIN_MAIN

#include <glib.h>

#include <stdio.h>
#include <errno.h>
#include <stddef.h>
#include <stdlib.h>
#include <signal.h>

#ifdef _WIN32
#include <wsutil/unicode-utils.h>
#include <wsutil/win32-utils.h>
#endif

#include <wsutil/filesystem.h>
#include <wsutil/socket.h>
#include <wsutil/inet_addr.h>
#include <wsutil/please_report_bug.h>
#include <wsutil/wslog.h>
#include <wsutil/ws_getopt.h>

#ifndef _WIN32
#include <sys/un.h>
#include <netinet/tcp.h>
#endif

#include <wsutil/strtoi.h>
#include <wsutil/version_info.h>

#include "sharkd.h"

#ifdef _WIN32
/* for windows support TCP sockets */
# define SHARKD_TCP_SUPPORT
#else
/* for other system support only local sockets */
# define SHARKD_UNIX_SUPPORT
#endif

static int mode = 0;
static socket_handle_t _server_fd = INVALID_SOCKET;

static socket_handle_t
socket_init(char *path)
{
    socket_handle_t fd = INVALID_SOCKET;
    char *err_msg;

    err_msg = ws_init_sockets();
    if (err_msg != NULL) {
        ws_warning("ERROR: %s", err_msg);
        g_free(err_msg);
        ws_warning("%s", please_report_bug());
        return fd;
    }

#ifdef SHARKD_UNIX_SUPPORT
    if (!strncmp(path, "unix:", 5))
    {
        struct sockaddr_un s_un;
        socklen_t s_un_len;

        path += 5;

        if (strlen(path) + 1 > sizeof(s_un.sun_path))
            return INVALID_SOCKET;

        fd = socket(AF_UNIX, SOCK_STREAM, 0);
        if (fd == INVALID_SOCKET)
            return INVALID_SOCKET;

        memset(&s_un, 0, sizeof(s_un));
        s_un.sun_family = AF_UNIX;
        (void) g_strlcpy(s_un.sun_path, path, sizeof(s_un.sun_path));

        s_un_len = (socklen_t)(offsetof(struct sockaddr_un, sun_path) + strlen(s_un.sun_path));

        if (s_un.sun_path[0] == '@')
            s_un.sun_path[0] = '\0';

        if (bind(fd, (struct sockaddr *) &s_un, s_un_len))
        {
            closesocket(fd);
            return INVALID_SOCKET;
        }
    }
    else
#endif

#ifdef SHARKD_TCP_SUPPORT
    if (!strncmp(path, "tcp:", 4))
    {
        struct sockaddr_in s_in;
        int one = 1;
        char *port_sep;
        guint16 port;

        path += 4;

        port_sep = strchr(path, ':');
        if (!port_sep)
            return INVALID_SOCKET;

        *port_sep = '\0';

        if (ws_strtou16(port_sep + 1, NULL, &port) == FALSE)
            return INVALID_SOCKET;

#ifdef _WIN32
        /* Need to use WSASocket() to disable overlapped I/O operations,
            this way on windows SOCKET can be used as HANDLE for stdin/stdout */
        fd = WSASocket(AF_INET, SOCK_STREAM, 0, NULL, 0, 0);
#else
        fd = socket(AF_INET, SOCK_STREAM, 0);
#endif
        if (fd == INVALID_SOCKET)
            return INVALID_SOCKET;

        s_in.sin_family = AF_INET;
        ws_inet_pton4(path, (ws_in4_addr *)&(s_in.sin_addr.s_addr));
        s_in.sin_port = g_htons(port);
        *port_sep = ':';

        setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, (void *) &one, sizeof(one));

        if (bind(fd, (struct sockaddr *) &s_in, sizeof(struct sockaddr_in)))
        {
            closesocket(fd);
            return INVALID_SOCKET;
        }
    }
    else
#endif
    {
        return INVALID_SOCKET;
    }

    if (listen(fd, SOMAXCONN))
    {
        closesocket(fd);
        return INVALID_SOCKET;
    }

    return fd;
}

static void
print_usage(FILE* output)
{
    fprintf(output, "\n");
    fprintf(output, "Usage: sharkd [<classic_options>|<gold_options>]\n");

    fprintf(output, "\n");
    fprintf(output, "Classic (classic_options):\n");
    fprintf(output, "  [-|<socket>]\n");
    fprintf(output, "\n");
    fprintf(output, "  <socket> examples:\n");
#ifdef SHARKD_UNIX_SUPPORT
    fprintf(output, "  - unix:/tmp/sharkd.sock - listen on unix file /tmp/sharkd.sock\n");
#endif
#ifdef SHARKD_TCP_SUPPORT
    fprintf(output, "  - tcp:127.0.0.1:4446 - listen on TCP port 4446\n");
#endif

    fprintf(output, "\n");
    fprintf(output, "Gold (gold_options):\n");
    fprintf(output, "  -a <socket>, --api <socket>\n");
    fprintf(output, "                           listen on this socket\n");
    fprintf(output, "  -h, --help               show this help information\n");
    fprintf(output, "  -v, --version            show version information\n");
    fprintf(output, "  -C <config profile>, --config-profile <config profile>\n");
    fprintf(output, "                           start with specified configuration profile\n");

    fprintf(output, "\n");
    fprintf(output, "  Examples:\n");
    fprintf(output, "    sharkd -C myprofile\n");
    fprintf(output, "    sharkd -a tcp:127.0.0.1:4446 -C myprofile\n");

    fprintf(output, "\n");
    fprintf(output, "See the sharkd page of the Wireshark wiki for full details.\n");
    fprintf(output, "\n");
}

int
sharkd_init(int argc, char **argv)
{
    /*
     * The leading + ensures that getopt_long() does not permute the argv[]
     * entries.
     *
     * We have to make sure that the first getopt_long() preserves the content
     * of argv[] for the subsequent getopt_long() call.
     *
     * We use getopt_long() in both cases to ensure that we're using a routine
     * whose permutation behavior we can control in the same fashion on all
     * platforms, and so that, if we ever need to process a long argument before
     * doing further initialization, we can do so.
     *
     * Glibc and Solaris libc document that a leading + disables permutation
     * of options, regardless of whether POSIXLY_CORRECT is set or not; *BSD
     * and macOS don't document it, but do so anyway.
     *
     * We do *not* use a leading - because the behavior of a leading - is
     * platform-dependent.
     */

#define OPTSTRING "+" "a:hmvC:"

    static const char    optstring[] = OPTSTRING;

    // right now we don't have any long options
    static const struct ws_option long_options[] = {
        {"api", ws_required_argument, NULL, 'a'},
        {"help", ws_no_argument, NULL, 'h'},
        {"version", ws_no_argument, NULL, 'v'},
        {"config-profile", ws_required_argument, NULL, 'C'},
        {0, 0, 0, 0 }
    };

    int opt;

#ifndef _WIN32
    pid_t pid;
#endif
    socket_handle_t fd;

    if (argc < 2)
    {
        print_usage(stderr);
        return -1;
    }

    // check for classic command line
    if (!strcmp(argv[1], "-") || argv[1][0] == 't' || argv[1][0] == 'u')
    {
        mode = SHARKD_MODE_CLASSIC_CONSOLE;

#ifndef _WIN32
        signal(SIGCHLD, SIG_IGN);
#endif

        if (!strcmp(argv[1], "-"))
        {
            mode = SHARKD_MODE_CLASSIC_CONSOLE;
        }
        else
        {
            fd = socket_init(argv[1]);
            if (fd == INVALID_SOCKET)
                return -1;
            _server_fd = fd;
            mode = SHARKD_MODE_CLASSIC_DAEMON;
        }
    }
    else
        mode = SHARKD_MODE_GOLD_CONSOLE;  // assume we are running as gold console

    if (mode >= SHARKD_MODE_GOLD_CONSOLE)
    {
        /*
           In Daemon Mode, we will come through here twice; once when we start the Daemon and
           once again after we have forked the session process.  The second time through, the
           session process has already had its stdin and stdout wired up to the TCP or UNIX
           socket and so in the original version of sharkd the session process is invoked with
           the command line: sharkd -

           When not using the classic command line, we want to spawn the session process with
           the complete command line with all the new options but with the -a option and
           parameter removed.  Invoking a second time with the -a option will cause a loop
           where we repeatedly spawn a new session process.
           */

        do {
            if (ws_optind > (argc - 1))
                break;

            opt = ws_getopt_long(argc, argv, optstring, long_options, NULL);

            switch (opt) {
                case 'C':        /* Configuration Profile */
                    if (profile_exists(ws_optarg, FALSE)) {
                        set_profile_name(ws_optarg);  // In Daemon Mode, we may need to do this again in the child process
                    }
                    else {
                        fprintf(stderr, "Configuration Profile \"%s\" does not exist\n", ws_optarg);
                        return -1;
                    }
                    break;

                case 'a':
                    fd = socket_init(ws_optarg);
                    if (fd == INVALID_SOCKET)
                        return -1;
                    _server_fd = fd;

                    fprintf(stderr, "Sharkd listening on: %s\n", ws_optarg);

                    mode = SHARKD_MODE_GOLD_DAEMON;
                    break;

                case 'h':
                    show_help_header("Daemon variant of Wireshark");
                    print_usage(stderr);
                    exit(0);
                    break;

                case 'm':
                    // m is an internal-only option used when the daemon session process is created
                    mode = SHARKD_MODE_GOLD_CONSOLE;
                    break;

                case 'v':         /* Show version and exit */
                    show_version();
                    exit(0);
                    break;

                default:
                    if (!ws_optopt)
                        fprintf(stderr, "This option isn't supported: %s\n", argv[ws_optind]);
                    fprintf(stderr, "Use sharkd -h for details of supported options\n");
                    exit(0);
                    break;
            }
        } while (opt != -1);
    }

    if (mode == SHARKD_MODE_CLASSIC_DAEMON || mode == SHARKD_MODE_GOLD_DAEMON)
    {
        /* all good - try to daemonize */
#ifndef _WIN32
        pid = fork();
        if (pid == -1)
            fprintf(stderr, "cannot go to background fork() failed: %s\n", g_strerror(errno));

        if (pid != 0)
        {
            /* parent */
            exit(0);
        }
#endif
    }

    return 0;
}

int
#ifndef _WIN32
sharkd_loop(int argc _U_, char* argv[] _U_)
#else
sharkd_loop(int argc _U_, char* argv[])
#endif
{
    if (mode == SHARKD_MODE_CLASSIC_CONSOLE || mode == SHARKD_MODE_GOLD_CONSOLE)
    {
        return sharkd_session_main(mode);
    }

    while (1)
    {
#ifndef _WIN32
        pid_t pid;
#else
        size_t i_handles;
        HANDLE handles[2];
        PROCESS_INFORMATION pi;
        STARTUPINFO si;
        char *exename;
        char command_line[2048];
#endif
        socket_handle_t fd;

        fd = accept(_server_fd, NULL, NULL);
        if (fd == INVALID_SOCKET)
        {
            fprintf(stderr, "cannot accept(): %s\n", g_strerror(errno));
            continue;
        }

        /* wireshark is not ready for handling multiple capture files in single process, so fork(), and handle it in separate process */
#ifndef _WIN32
        pid = fork();
        if (pid == 0)
        {
            closesocket(_server_fd);
            /* redirect stdin, stdout to socket */
            dup2(fd, 0);
            dup2(fd, 1);
            close(fd);

            exit(sharkd_session_main(mode));
        }

        if (pid == -1)
        {
            fprintf(stderr, "cannot fork(): %s\n", g_strerror(errno));
        }

#else
        memset(&pi, 0, sizeof(pi));
        memset(&si, 0, sizeof(si));

        si.cb = sizeof(si);
        si.dwFlags = STARTF_USESTDHANDLES | STARTF_USESHOWWINDOW;
        si.hStdInput = (HANDLE) fd;
        si.hStdOutput = (HANDLE) fd;
        si.hStdError = GetStdHandle(STD_ERROR_HANDLE);

        i_handles = 0;
        handles[i_handles++] = (HANDLE)fd;
        if (si.hStdError != NULL) {
            handles[i_handles++] = si.hStdError;
        }

        exename = get_executable_path("sharkd");

        // we need to pass in all of the command line parameters except the -a parameter
        // passing in -a at this point would could a loop, each iteration of which would generate a new session process
        memset(&command_line, 0, sizeof(command_line));

        if (mode <= SHARKD_MODE_CLASSIC_DAEMON)
        {
            (void) g_strlcat(command_line, "sharkd.exe -", sizeof(command_line));
        }
        else
        {
            // The -m option used here is an internal-only option that notifies the child process that it should
            // run in Gold Console mode
            (void) g_strlcat(command_line, "sharkd.exe -m", sizeof(command_line));

            for (int i = 1; i < argc; i++)
            {
                if (
                        !g_ascii_strncasecmp(argv[i], "-a", (guint)strlen(argv[i]))
                        || !g_ascii_strncasecmp(argv[i], "--api", (guint)strlen(argv[i]))
                   )
                {
                    i++;  // skip the socket details
                }
                else
                {
                    (void) g_strlcat(command_line, " ", sizeof(command_line));
                    (void) g_strlcat(command_line, argv[i], sizeof(command_line));
                }
            }
        }

        if (!win32_create_process(exename, command_line, NULL, NULL, i_handles, handles, 0, NULL, NULL, &si, &pi))
        {
            fprintf(stderr, "win32_create_process(%s) failed\n", exename);
        }
        else
        {
            CloseHandle(pi.hThread);
        }

        g_free(exename);
#endif

        closesocket(fd);
    }
    return 0;
}