/*

 * Dropbear - a SSH2 server

 * 

 * Copyright (c) 2002,2003 Matt Johnston

 * All rights reserved.

 * 

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 * 

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 * 

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

 * SOFTWARE. */

#include "includes.h"

#include "runopts.h"

#include "signkey.h"

#include "buffer.h"

#include "dbutil.h"

#include "algo.h"

#include "ecdsa.h"

#include <grp.h>

svr_runopts svr_opts; /* GLOBAL */

static void printhelp(const char * progname);

static void addportandaddress(const char* spec);

static void loadhostkey(const char *keyfile, int fatal_duplicate);

static void addhostkey(const char *keyfile);

static void load_banner();

static void printhelp(const char * progname) {

  fprintf(stderr, "Dropbear server v%s https://matt.ucc.asn.au/dropbear/dropbear.html\n"

          "Usage: %s [options]\n"

          "-b bannerfile  Display the contents of bannerfile"

          " before user login\n"

          "   (default: none)\n"

          "-r keyfile      Specify hostkeys (repeatable)\n"

          "   defaults: \n"

#if DROPBEAR_DSS

          "   - dss %s\n"

#endif

#if DROPBEAR_RSA

          "   - rsa %s\n"

#endif

#if DROPBEAR_ECDSA

          "   - ecdsa %s\n"

#endif

#if DROPBEAR_ED25519

          "   - ed25519 %s\n"

#endif

#if DROPBEAR_DELAY_HOSTKEY

          "-R   Create hostkeys as required\n" 

#endif

          "-F   Don't fork into background\n"

          "-e   Pass on server process environment to child process\n"

#ifdef DISABLE_SYSLOG

          "(Syslog support not compiled in, using stderr)\n"

#else

          "-E   Log to stderr rather than syslog\n"

#endif

#if DO_MOTD

          "-m   Don't display the motd on login\n"

#endif

          "-w   Disallow root logins\n"

#ifdef HAVE_GETGROUPLIST

          "-G   Restrict logins to members of specified group\n"

#endif

#if DROPBEAR_SVR_PASSWORD_AUTH || DROPBEAR_SVR_PAM_AUTH

          "-s   Disable password logins\n"

          "-g   Disable password logins for root\n"

          "-B   Allow blank password logins\n"

          "-t   Enable two-factor authentication (both password and public key required)\n"

#endif

          "-T   Maximum authentication tries (default %d)\n"

#if DROPBEAR_SVR_LOCALTCPFWD

          "-j   Disable local port forwarding\n"

#endif

#if DROPBEAR_SVR_REMOTETCPFWD

          "-k   Disable remote port forwarding\n"

          "-a   Allow connections to forwarded ports from any host\n"

          "-c command Force executed command\n"

#endif

          "-p [address:]port\n"

          "   Listen on specified tcp port (and optionally address),\n"

          "   up to %d can be specified\n"

          "   (default port is %s if none specified)\n"

          "-P PidFile Create pid file PidFile\n"

          "   (default %s)\n"

#ifdef SO_BINDTODEVICE

          "-l <interface>\n"

          "   interface to bind on\n"

#endif

#if INETD_MODE

          "-i   Start for inetd\n"

#endif

          "-W <receive_window_buffer> (default %d, larger may be faster, max 10MB)\n"

          "-K <keepalive>  (0 is never, default %d, in seconds)\n"

          "-I <idle_timeout>  (0 is never, default %d, in seconds)\n"

          "-z    disable QoS\n"

#if DROPBEAR_PLUGIN

                                        "-A <authplugin>[,<options>]\n"

                                        "               Enable external public key auth through <authplugin>\n"

#endif

          "-V    Version\n"

#if DEBUG_TRACE

          "-v    verbose (repeat for more verbose)\n"

#endif

          ,DROPBEAR_VERSION, progname,

#if DROPBEAR_DSS

          DSS_PRIV_FILENAME,

#endif

#if DROPBEAR_RSA

          RSA_PRIV_FILENAME,

#endif

#if DROPBEAR_ECDSA

          ECDSA_PRIV_FILENAME,

#endif

#if DROPBEAR_ED25519

          ED25519_PRIV_FILENAME,

#endif

          MAX_AUTH_TRIES,

          DROPBEAR_MAX_PORTS, DROPBEAR_DEFPORT, DROPBEAR_PIDFILE,

          DEFAULT_RECV_WINDOW, DEFAULT_KEEPALIVE, DEFAULT_IDLE_TIMEOUT);

}

void svr_getopts(int argc, char ** argv) {

  unsigned int i, j;

  char ** next = NULL;

  int nextisport = 0;

  char* recv_window_arg = NULL;

  char* keepalive_arg = NULL;

  char* idle_timeout_arg = NULL;

  char* maxauthtries_arg = NULL;

  char* reexec_fd_arg = NULL;

  char* keyfile = NULL;

  char c;

#if DROPBEAR_PLUGIN

        char* pubkey_plugin = NULL;

#endif

  /* see printhelp() for options */

  svr_opts.bannerfile = NULL;

  svr_opts.banner = NULL;

  svr_opts.forced_command = NULL;

  svr_opts.forkbg = 1;

  svr_opts.norootlogin = 0;

#ifdef HAVE_GETGROUPLIST

  svr_opts.restrict_group = NULL;

  svr_opts.restrict_group_gid = 0;

#endif

  svr_opts.noauthpass = 0;

  svr_opts.norootpass = 0;

  svr_opts.allowblankpass = 0;

  svr_opts.multiauthmethod = 0;

  svr_opts.maxauthtries = MAX_AUTH_TRIES;

  svr_opts.inetdmode = 0;

  svr_opts.portcount = 0;

  svr_opts.hostkey = NULL;

  svr_opts.delay_hostkey = 0;

  svr_opts.pidfile = expand_homedir_path(DROPBEAR_PIDFILE);

#if DROPBEAR_SVR_LOCALTCPFWD

  svr_opts.nolocaltcp = 0;

#endif

#if DROPBEAR_SVR_REMOTETCPFWD

  svr_opts.noremotetcp = 0;

#endif

#if DROPBEAR_PLUGIN

        svr_opts.pubkey_plugin = NULL;

        svr_opts.pubkey_plugin_options = NULL;

#endif

  svr_opts.pass_on_env = 0;

  svr_opts.reexec_childpipe = -1;

#ifndef DISABLE_ZLIB

  opts.compress_mode = DROPBEAR_COMPRESS_DELAYED;

#endif 

  /* not yet

  opts.ipv4 = 1;

  opts.ipv6 = 1;

  */

#if DO_MOTD

  svr_opts.domotd = 1;

#endif

#ifndef DISABLE_SYSLOG

  opts.usingsyslog = 1;

#endif

  opts.recv_window = DEFAULT_RECV_WINDOW;

  opts.keepalive_secs = DEFAULT_KEEPALIVE;

  opts.idle_timeout_secs = DEFAULT_IDLE_TIMEOUT;

#if DROPBEAR_SVR_REMOTETCPFWD

  opts.listen_fwd_all = 0;

#endif

  opts.disable_ip_tos = 0;

  for (i = 1; i < (unsigned int)argc; i++) {

    if (argv[i][0] != '-' || argv[i][1] == '\0')

      dropbear_exit("Invalid argument: %s", argv[i]);

    for (j = 1; (c = argv[i][j]) != '\0' && !next && !nextisport; j++) {

      switch (c) {

        case 'b':

          next = &svr_opts.bannerfile;

          break;

        case 'c':

          next = &svr_opts.forced_command;

          break;

        case 'd':

        case 'r':

          next = &keyfile;

          break;

        case 'R':

          svr_opts.delay_hostkey = 1;

          break;

        case 'F':

          svr_opts.forkbg = 0;

          break;

#ifndef DISABLE_SYSLOG

        case 'E':

          opts.usingsyslog = 0;

          break;

#endif

        case 'e':

          svr_opts.pass_on_env = 1;

          break;

#if DROPBEAR_SVR_LOCALTCPFWD

        case 'j':

          svr_opts.nolocaltcp = 1;

          break;

#endif

#if DROPBEAR_SVR_REMOTETCPFWD

        case 'k':

          svr_opts.noremotetcp = 1;

          break;

        case 'a':

          opts.listen_fwd_all = 1;

          break;

#endif

#if INETD_MODE

        case 'i':

          svr_opts.inetdmode = 1;

          break;

#endif

#if DROPBEAR_DO_REEXEC && NON_INETD_MODE

        /* For internal use by re-exec */

        case '2':

          next = &reexec_fd_arg;

          break;

#endif

        case 'p':

          nextisport = 1;

          break;

        case 'P':

          next = &svr_opts.pidfile;

          break;

#ifdef SO_BINDTODEVICE

        case 'l':

          next = &svr_opts.interface;

          break;

#endif

#if DO_MOTD

        /* motd is displayed by default, -m turns it off */

        case 'm':

          svr_opts.domotd = 0;

          break;

#endif

        case 'w':

          svr_opts.norootlogin = 1;

          break;

#ifdef HAVE_GETGROUPLIST

        case 'G':

          next = &svr_opts.restrict_group;

          break;

#endif

        case 'W':

          next = &recv_window_arg;

          break;

        case 'K':

          next = &keepalive_arg;

          break;

        case 'I':

          next = &idle_timeout_arg;

          break;

        case 'T':

          next = &maxauthtries_arg;

          break;

#if DROPBEAR_SVR_PASSWORD_AUTH || DROPBEAR_SVR_PAM_AUTH

        case 's':

          svr_opts.noauthpass = 1;

          break;

        case 'g':

          svr_opts.norootpass = 1;

          break;

        case 'B':

          svr_opts.allowblankpass = 1;

          break;

        case 't':

          svr_opts.multiauthmethod = 1;

          break;

#endif

        case 'h':

          printhelp(argv[0]);

          exit(EXIT_SUCCESS);

          break;

        case 'u':

          /* backwards compatibility with old urandom option */

          break;

#if DROPBEAR_PLUGIN

                                case 'A':

                                        next = &pubkey_plugin;

                                        break;

#endif

#if DEBUG_TRACE

        case 'v':

          debug_trace++;

          break;

#endif

        case 'V':

          print_version();

          exit(EXIT_SUCCESS);

          break;

        case 'z':

          opts.disable_ip_tos = 1;

          break;

        default:

          fprintf(stderr, "Invalid option -%c\n", c);

          printhelp(argv[0]);

          exit(EXIT_FAILURE);

          break;

      }

    }

    if (!next && !nextisport)

      continue;

    if (c == '\0') {

      i++;

      j = 0;

      if (!argv[i]) {

        dropbear_exit("Missing argument");

      }

    }

    if (nextisport) {

      addportandaddress(&argv[i][j]);

      nextisport = 0;

    } else if (next) {

      *next = &argv[i][j];

      if (*next == NULL) {

        dropbear_exit("Invalid null argument");

      }

      next = NULL;

      if (keyfile) {

        addhostkey(keyfile);

        keyfile = NULL;

      }

    }

  }

  /* Set up listening ports */

  if (svr_opts.portcount == 0) {

    svr_opts.ports[0] = m_strdup(DROPBEAR_DEFPORT);

    svr_opts.addresses[0] = m_strdup(DROPBEAR_DEFADDRESS);

    svr_opts.portcount = 1;

  }

  if (svr_opts.bannerfile) {

    load_banner();

  }

#ifdef HAVE_GETGROUPLIST

  if (svr_opts.restrict_group) {

    struct group *restrictedgroup = getgrnam(svr_opts.restrict_group);

    if (restrictedgroup){

      svr_opts.restrict_group_gid = restrictedgroup->gr_gid;

    } else {

      dropbear_exit("Cannot restrict logins to group '%s' as the group does not exist", svr_opts.restrict_group);

    }

  }

#endif

  if (recv_window_arg) {

    parse_recv_window(recv_window_arg);

  }

  if (maxauthtries_arg) {

    unsigned int val = 0;

    if (m_str_to_uint(maxauthtries_arg, &val) == DROPBEAR_FAILURE 

      || val == 0) {

      dropbear_exit("Bad maxauthtries '%s'", maxauthtries_arg);

    }

    svr_opts.maxauthtries = val;

  }

  if (keepalive_arg) {

    unsigned int val;

    if (m_str_to_uint(keepalive_arg, &val) == DROPBEAR_FAILURE) {

      dropbear_exit("Bad keepalive '%s'", keepalive_arg);

    }

    opts.keepalive_secs = val;

  }

  if (idle_timeout_arg) {

    unsigned int val;

    if (m_str_to_uint(idle_timeout_arg, &val) == DROPBEAR_FAILURE) {

      dropbear_exit("Bad idle_timeout '%s'", idle_timeout_arg);

    }

    opts.idle_timeout_secs = val;

  }

  if (svr_opts.forced_command) {

    dropbear_log(LOG_INFO, "Forced command set to '%s'", svr_opts.forced_command);

  }

  if (svr_opts.interface) {

    dropbear_log(LOG_INFO, "Binding to interface '%s'", svr_opts.interface);

  }

  if (reexec_fd_arg) {

    if (m_str_to_uint(reexec_fd_arg, &svr_opts.reexec_childpipe) == DROPBEAR_FAILURE

      || svr_opts.reexec_childpipe < 0) {

      dropbear_exit("Bad -2");

    }

  }

#if INETD_MODE

  if (svr_opts.inetdmode && (

    opts.usingsyslog == 0

#if DEBUG_TRACE

    || debug_trace

#endif

    )) {

    /* log output goes to stderr which would get sent over the inetd network socket */

    dropbear_exit("Dropbear inetd mode is incompatible with debug -v or non-syslog");

  }

#endif

  if (svr_opts.multiauthmethod && svr_opts.noauthpass) {

    dropbear_exit("-t and -s are incompatible");

  }

#if DROPBEAR_PLUGIN

  if (pubkey_plugin) {

    svr_opts.pubkey_plugin = m_strdup(pubkey_plugin);

    char *args = strchr(svr_opts.pubkey_plugin, ',');

    if (args) {

      *args='\0';

      ++args;

    }

    svr_opts.pubkey_plugin_options = args;

  }

#endif

}

static void addportandaddress(const char* spec) {

  char *port = NULL, *address = NULL;

  if (svr_opts.portcount >= DROPBEAR_MAX_PORTS) {

    return;

  }

  if (split_address_port(spec, &address, &port) == DROPBEAR_FAILURE) {

    dropbear_exit("Bad -p argument");

  }

  /* A bare port */

  if (!port) {

    port = address;

    address = NULL;

  }

  if (!address) {

    /* no address given -> fill in the default address */

    address = m_strdup(DROPBEAR_DEFADDRESS);

  }

  if (port[0] == '\0') {

    /* empty port -> exit */

    dropbear_exit("Bad port");

  }

  svr_opts.ports[svr_opts.portcount] = port;

  svr_opts.addresses[svr_opts.portcount] = address;

  svr_opts.portcount++;

}

static void disablekey(enum signature_type type) {

  int i;

  TRACE(("Disabling key type %d", type))

  for (i = 0; sigalgs[i].name != NULL; i++) {

    if ((int)sigalgs[i].val == (int)type) {

      sigalgs[i].usable = 0;

      break;

    }

  }

}

static void loadhostkey_helper(const char *name, void** src, void** dst, int fatal_duplicate) {

  if (*dst) {

    if (fatal_duplicate) {

      dropbear_exit("Only one %s key can be specified", name);

    }

  } else {

    *dst = *src;

    *src = NULL;

  }

}

/* Must be called after syslog/etc is working */

static void loadhostkey(const char *keyfile, int fatal_duplicate) {

  sign_key * read_key = new_sign_key();

  char *expand_path = expand_homedir_path(keyfile);

  enum signkey_type type = DROPBEAR_SIGNKEY_ANY;

  if (readhostkey(expand_path, read_key, &type) == DROPBEAR_FAILURE) {

    if (!svr_opts.delay_hostkey) {

      dropbear_log(LOG_WARNING, "Failed loading %s", expand_path);

    }

  }

  m_free(expand_path);

#if DROPBEAR_RSA

  if (type == DROPBEAR_SIGNKEY_RSA) {

    loadhostkey_helper("RSA", (void**)&read_key->rsakey, (void**)&svr_opts.hostkey->rsakey, fatal_duplicate);

  }

#endif

#if DROPBEAR_DSS

  if (type == DROPBEAR_SIGNKEY_DSS) {

    loadhostkey_helper("DSS", (void**)&read_key->dsskey, (void**)&svr_opts.hostkey->dsskey, fatal_duplicate);

  }

#endif

#if DROPBEAR_ECDSA

#if DROPBEAR_ECC_256

  if (type == DROPBEAR_SIGNKEY_ECDSA_NISTP256) {

    loadhostkey_helper("ECDSA256", (void**)&read_key->ecckey256, (void**)&svr_opts.hostkey->ecckey256, fatal_duplicate);

  }

#endif

#if DROPBEAR_ECC_384

  if (type == DROPBEAR_SIGNKEY_ECDSA_NISTP384) {

    loadhostkey_helper("ECDSA384", (void**)&read_key->ecckey384, (void**)&svr_opts.hostkey->ecckey384, fatal_duplicate);

  }

#endif

#if DROPBEAR_ECC_521

  if (type == DROPBEAR_SIGNKEY_ECDSA_NISTP521) {

    loadhostkey_helper("ECDSA521", (void**)&read_key->ecckey521, (void**)&svr_opts.hostkey->ecckey521, fatal_duplicate);

  }

#endif

#endif /* DROPBEAR_ECDSA */

#if DROPBEAR_ED25519

  if (type == DROPBEAR_SIGNKEY_ED25519) {

    loadhostkey_helper("ed25519", (void**)&read_key->ed25519key, (void**)&svr_opts.hostkey->ed25519key, fatal_duplicate);

  }

#endif

  sign_key_free(read_key);

  TRACE(("leave loadhostkey"))

}

static void addhostkey(const char *keyfile) {

  if (svr_opts.num_hostkey_files >= MAX_HOSTKEYS) {

    dropbear_exit("Too many hostkeys");

  }

  svr_opts.hostkey_files[svr_opts.num_hostkey_files] = m_strdup(keyfile);

  svr_opts.num_hostkey_files++;

}

void load_all_hostkeys() {

  int i;

  int any_keys = 0;

#if DROPBEAR_ECDSA

  int loaded_any_ecdsa = 0;

#endif

  svr_opts.hostkey = new_sign_key();

  for (i = 0; i < svr_opts.num_hostkey_files; i++) {

    char *hostkey_file = svr_opts.hostkey_files[i];

    loadhostkey(hostkey_file, 1);

    m_free(hostkey_file);

  }

  /* Only load default host keys if a host key is not specified by the user */

  if (svr_opts.num_hostkey_files == 0) {

#if DROPBEAR_RSA

    loadhostkey(RSA_PRIV_FILENAME, 0);

#endif

#if DROPBEAR_DSS

    loadhostkey(DSS_PRIV_FILENAME, 0);

#endif

#if DROPBEAR_ECDSA

    loadhostkey(ECDSA_PRIV_FILENAME, 0);

#endif

#if DROPBEAR_ED25519

    loadhostkey(ED25519_PRIV_FILENAME, 0);

#endif

  }

#if DROPBEAR_RSA

  if (!svr_opts.delay_hostkey && !svr_opts.hostkey->rsakey) {

    disablekey(DROPBEAR_SIGNATURE_RSA_SHA256);

    disablekey(DROPBEAR_SIGNATURE_RSA_SHA1);

  } else {

    any_keys = 1;

  }

#endif

#if DROPBEAR_DSS

  if (!svr_opts.delay_hostkey && !svr_opts.hostkey->dsskey) {

    disablekey(DROPBEAR_SIGNATURE_DSS);

  } else {

    any_keys = 1;

  }

#endif

#if DROPBEAR_ECDSA

  /* We want to advertise a single ecdsa algorithm size.

  - If there is a ecdsa hostkey at startup we choose that that size.

  - If we generate at runtime we choose the default ecdsa size.

  - Otherwise no ecdsa keys will be advertised */

  /* check if any keys were loaded at startup */

  loaded_any_ecdsa = 

    0

#if DROPBEAR_ECC_256

    || svr_opts.hostkey->ecckey256

#endif

#if DROPBEAR_ECC_384

    || svr_opts.hostkey->ecckey384

#endif

#if DROPBEAR_ECC_521

    || svr_opts.hostkey->ecckey521

#endif

    ;

  any_keys |= loaded_any_ecdsa;

  /* Or an ecdsa key could be generated at runtime */

  any_keys |= svr_opts.delay_hostkey;

  /* At most one ecdsa key size will be left enabled */

#if DROPBEAR_ECC_256

  if (!svr_opts.hostkey->ecckey256

    && (!svr_opts.delay_hostkey || loaded_any_ecdsa || ECDSA_DEFAULT_SIZE != 256 )) {

    disablekey(DROPBEAR_SIGNATURE_ECDSA_NISTP256);

  }

#endif

#if DROPBEAR_ECC_384

  if (!svr_opts.hostkey->ecckey384

    && (!svr_opts.delay_hostkey || loaded_any_ecdsa || ECDSA_DEFAULT_SIZE != 384 )) {

    disablekey(DROPBEAR_SIGNATURE_ECDSA_NISTP384);

  }

#endif

#if DROPBEAR_ECC_521

  if (!svr_opts.hostkey->ecckey521

    && (!svr_opts.delay_hostkey || loaded_any_ecdsa || ECDSA_DEFAULT_SIZE != 521 )) {

    disablekey(DROPBEAR_SIGNATURE_ECDSA_NISTP521);

  }

#endif

#endif /* DROPBEAR_ECDSA */

#if DROPBEAR_ED25519

  if (!svr_opts.delay_hostkey && !svr_opts.hostkey->ed25519key) {

    disablekey(DROPBEAR_SIGNATURE_ED25519);

  } else {

    any_keys = 1;

  }

#endif

#if DROPBEAR_SK_ECDSA

  disablekey(DROPBEAR_SIGNATURE_SK_ECDSA_NISTP256);

#endif 

#if DROPBEAR_SK_ED25519

  disablekey(DROPBEAR_SIGNATURE_SK_ED25519);

#endif

  if (!any_keys) {

    dropbear_exit("No hostkeys available. 'dropbear -R' may be useful or run dropbearkey.");

  }

}

static void load_banner() {

  struct stat buf;

  if (stat(svr_opts.bannerfile, &buf) != 0) {

    dropbear_log(LOG_WARNING, "Error opening banner file '%s'",

        svr_opts.bannerfile);

    return;

  }

  if (buf.st_size > MAX_BANNER_SIZE) {

    dropbear_log(LOG_WARNING, "Banner file too large, max is %d bytes",

        MAX_BANNER_SIZE);

    return;

  }

  svr_opts.banner = buf_new(buf.st_size);

  if (buf_readfile(svr_opts.banner, svr_opts.bannerfile) != DROPBEAR_SUCCESS) {

    dropbear_log(LOG_WARNING, "Error reading banner file '%s'",

        svr_opts.bannerfile);

    buf_free(svr_opts.banner);

    svr_opts.banner = NULL;

    return;

  }

  buf_setpos(svr_opts.banner, 0);

}