/*

 * Dropbear SSH

 * 

 * Copyright (c) 2002,2003 Matt Johnston

 * Copyright (c) 2004 by Mihnea Stoenescu

 * 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 "buffer.h"

#include "dbutil.h"

#include "session.h"

#include "ssh.h"

#include "runopts.h"

#include "auth.h"

#include "agentfwd.h"

#if DROPBEAR_CLI_PUBKEY_AUTH

static void send_msg_userauth_pubkey(sign_key *key, enum signature_type sigtype, int realsign);

/* Called when we receive a SSH_MSG_USERAUTH_FAILURE for a pubkey request.

 * We use it to remove the key we tried from the list */

void cli_pubkeyfail() {

  m_list_elem *iter;

  for (iter = cli_opts.privkeys->first; iter; iter = iter->next) {

    sign_key *iter_key = (sign_key*)iter->item;

    if (iter_key == cli_ses.lastprivkey)

    {

      /* found the failing key */

      list_remove(iter);

      sign_key_free(iter_key);

      cli_ses.lastprivkey = NULL;

      return;

    }

  }

}

void recv_msg_userauth_pk_ok() {

  m_list_elem *iter;

  buffer* keybuf = NULL;

  char* algotype = NULL;

  unsigned int algolen;

  enum signkey_type keytype;

  enum signature_type sigtype;

  unsigned int remotelen;

  TRACE(("enter recv_msg_userauth_pk_ok"))

  algotype = buf_getstring(ses.payload, &algolen);

  sigtype = signature_type_from_name(algotype, algolen);

  if (sigtype == DROPBEAR_SIGNATURE_NONE) {

    /* Server replied with an algorithm that we didn't send */

    dropbear_exit("Bad pk_ok");

  }

  keytype = signkey_type_from_signature(sigtype);

  TRACE(("recv_msg_userauth_pk_ok: type %d", sigtype))

  m_free(algotype);

  keybuf = buf_new(MAX_PUBKEY_SIZE);

  remotelen = buf_getint(ses.payload);

  /* Iterate through our keys, find which one it was that matched, and

   * send a real request with that key */

  for (iter = cli_opts.privkeys->first; iter; iter = iter->next) {

    sign_key *key = (sign_key*)iter->item;

    if (key->type != keytype) {

      /* Types differed */

      TRACE(("types differed"))

      continue;

    }

    /* Now we compare the contents of the key */

    keybuf->pos = keybuf->len = 0;

    buf_put_pub_key(keybuf, key, keytype);

    buf_setpos(keybuf, 0);

    buf_incrpos(keybuf, 4); /* first int is the length of the remainder (ie

                   remotelen) which has already been taken from

                   the remote buffer */

    if (keybuf->len-4 != remotelen) {

      TRACE(("lengths differed: localh %d remote %d", keybuf->len, remotelen))

      /* Lengths differed */

      continue;

    }

    if (memcmp(buf_getptr(keybuf, remotelen),

          buf_getptr(ses.payload, remotelen), remotelen) != 0) {

      /* Data didn't match this key */

      TRACE(("data differed"))

      continue;

    }

    /* Success */

    break;

  }

  buf_free(keybuf);

  if (iter != NULL) {

    TRACE(("matching key"))

    /* XXX TODO: if it's an encrypted key, here we ask for their

     * password */

    send_msg_userauth_pubkey((sign_key*)iter->item, sigtype, 1);

  } else {

    TRACE(("That was whacky. We got told that a key was valid, but it didn't match our list. Sounds like dodgy code on Dropbear's part"))

  }

  TRACE(("leave recv_msg_userauth_pk_ok"))

}

static void cli_buf_put_sign(buffer* buf, sign_key *key, enum signature_type sigtype,

      const buffer *data_buf) {

#if DROPBEAR_CLI_AGENTFWD

  /* TODO: rsa-sha256 agent */

  if (key->source == SIGNKEY_SOURCE_AGENT) {

    /* Format the agent signature ourselves, as buf_put_sign would. */

    buffer *sigblob;

    sigblob = buf_new(MAX_PUBKEY_SIZE);

    agent_buf_sign(sigblob, key, data_buf, sigtype);

    buf_putbufstring(buf, sigblob);

    buf_free(sigblob);

  } else 

#endif /* DROPBEAR_CLI_AGENTFWD */

  {

    buf_put_sign(buf, key, sigtype, data_buf);

  }

}

static void send_msg_userauth_pubkey(sign_key *key, enum signature_type sigtype, int realsign) {

  const char *algoname = NULL;

  unsigned int algolen;

  buffer* sigbuf = NULL;

  enum signkey_type keytype = signkey_type_from_signature(sigtype);

  DEBUG1(("enter send_msg_userauth_pubkey %s", signature_name_from_type(sigtype, NULL)))

  CHECKCLEARTOWRITE();

  buf_putbyte(ses.writepayload, SSH_MSG_USERAUTH_REQUEST);

  buf_putstring(ses.writepayload, cli_opts.username,

      strlen(cli_opts.username));

  buf_putstring(ses.writepayload, SSH_SERVICE_CONNECTION,

      SSH_SERVICE_CONNECTION_LEN);

  buf_putstring(ses.writepayload, AUTH_METHOD_PUBKEY,

      AUTH_METHOD_PUBKEY_LEN);

  buf_putbyte(ses.writepayload, realsign);

  algoname = signature_name_from_type(sigtype, &algolen);

  buf_putstring(ses.writepayload, algoname, algolen);

  buf_put_pub_key(ses.writepayload, key, keytype);

  if (realsign) {

    TRACE(("realsign"))

    /* We put the signature as well - this contains string(session id), then

     * the contents of the write payload to this point */

    sigbuf = buf_new(4 + ses.session_id->len + ses.writepayload->len);

    buf_putbufstring(sigbuf, ses.session_id);

    buf_putbytes(sigbuf, ses.writepayload->data, ses.writepayload->len);

    cli_buf_put_sign(ses.writepayload, key, sigtype, sigbuf);

    buf_free(sigbuf); /* Nothing confidential in the buffer */

    cli_ses.is_trivial_auth = 0;

  }

  encrypt_packet();

  TRACE(("leave send_msg_userauth_pubkey"))

}

/* Returns 1 if a key was tried */

int cli_auth_pubkey() {

  enum signature_type sigtype = DROPBEAR_SIGNATURE_NONE;

  TRACE(("enter cli_auth_pubkey"))

#if DROPBEAR_CLI_AGENTFWD

  if (!cli_opts.agent_keys_loaded) {

    /* get the list of available keys from the agent */

    cli_load_agent_keys(cli_opts.privkeys);

    cli_opts.agent_keys_loaded = 1;

    TRACE(("cli_auth_pubkey: agent keys loaded"))

  }

#endif

  /* iterate through privkeys to remove ones not allowed in server-sig-algs */

  while (cli_opts.privkeys->first) {

    sign_key * key = (sign_key*)cli_opts.privkeys->first->item;

    if (cli_ses.server_sig_algs) {

#if DROPBEAR_RSA

      if (key->type == DROPBEAR_SIGNKEY_RSA) {

#if DROPBEAR_RSA_SHA256

        if (buf_has_algo(cli_ses.server_sig_algs, SSH_SIGNATURE_RSA_SHA256) 

            == DROPBEAR_SUCCESS) {

          sigtype = DROPBEAR_SIGNATURE_RSA_SHA256;

          TRACE(("server-sig-algs allows rsa sha256"))

          break;

        }

#endif /* DROPBEAR_RSA_SHA256 */

#if DROPBEAR_RSA_SHA1

        if (buf_has_algo(cli_ses.server_sig_algs, SSH_SIGNKEY_RSA)

            == DROPBEAR_SUCCESS) {

          sigtype = DROPBEAR_SIGNATURE_RSA_SHA1;

          TRACE(("server-sig-algs allows rsa sha1"))

          break;

        }

#endif /* DROPBEAR_RSA_SHA256 */

      } else

#endif /* DROPBEAR_RSA */

      {

        /* Not RSA */

        const char *name = NULL;

        sigtype = signature_type_from_signkey(key->type);

        name = signature_name_from_type(sigtype, NULL);

        if (buf_has_algo(cli_ses.server_sig_algs, name)

            == DROPBEAR_SUCCESS) {

          TRACE(("server-sig-algs allows %s", name))

          break;

        }

      }

      /* No match, skip this key */

      TRACE(("server-sig-algs no match keytype %d, skipping", key->type))

      key = list_remove(cli_opts.privkeys->first);

      sign_key_free(key); 

      continue;

    } else {

      /* Server didn't provide a server-sig-algs list, we'll 

         assume all except rsa-sha256 are OK. */

#if DROPBEAR_RSA

      if (key->type == DROPBEAR_SIGNKEY_RSA) {

#if DROPBEAR_RSA_SHA1

        sigtype = DROPBEAR_SIGNATURE_RSA_SHA1;

        TRACE(("no server-sig-algs, using rsa sha1"))

        break;

#else

        /* only support rsa-sha256, skip this key */

        TRACE(("no server-sig-algs, skipping rsa sha256"))

        key = list_remove(cli_opts.privkeys->first);

        sign_key_free(key); 

        continue;

#endif

      } /* key->type == DROPBEAR_SIGNKEY_RSA */

#endif /* DROPBEAR_RSA */

      sigtype = signature_type_from_signkey(key->type);

      TRACE(("no server-sig-algs, using key"))

      break;

    }

  }

  if (cli_opts.privkeys->first) {

    sign_key * key = (sign_key*)cli_opts.privkeys->first->item;

    /* Send a trial request */

    send_msg_userauth_pubkey(key, sigtype, 0);

    cli_ses.lastprivkey = key;

    TRACE(("leave cli_auth_pubkey-success"))

    return 1;

  } else {

    /* no more keys left */

    TRACE(("leave cli_auth_pubkey-failure"))

    return 0;

  }

}

void cli_auth_pubkey_cleanup() {

#if DROPBEAR_CLI_AGENTFWD

  m_close(cli_opts.agent_fd);

  cli_opts.agent_fd = -1;

#endif

  while (cli_opts.privkeys->first) {

    sign_key * key = list_remove(cli_opts.privkeys->first);

    sign_key_free(key);

  }

}

#endif /* Pubkey auth */