niceSOFT/libssh | Gitverse

src/server.c
1 265 строк37 KB
David Wedderwille
connector: Fallback on the socket output callback
22 фев 2019, 13:42
22 фев 2019, 13:424af7736
/*
 * server.c - functions for creating a SSH server
 *
 * This file is part of the SSH Library
 *
 * Copyright (c) 2004-2013 by Aris Adamantiadis
 *
 * The SSH Library is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or (at your
 * option) any later version.
 *
 * The SSH Library 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 Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with the SSH Library; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 */

#include "config.h"

#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#ifdef _WIN32
# include <winsock2.h>
# include <ws2tcpip.h>

  /*
   * <wspiapi.h> is necessary for getaddrinfo before Windows XP, but it isn't
   * available on some platforms like MinGW.
   */
# ifdef HAVE_WSPIAPI_H
#  include <wspiapi.h>
# endif
#else
# include <netinet/in.h>
#endif

#include "libssh/priv.h"
#include "libssh/libssh.h"
#include "libssh/server.h"
#include "libssh/ssh2.h"
#include "libssh/buffer.h"
#include "libssh/packet.h"
#include "libssh/socket.h"
#include "libssh/session.h"
#include "libssh/kex.h"
#include "libssh/misc.h"
#include "libssh/pki.h"
#include "libssh/dh.h"
#include "libssh/messages.h"
#include "libssh/options.h"
#include "libssh/curve25519.h"

#define set_status(session, status) do {\
        if (session->common.callbacks && session->common.callbacks->connect_status_function) \
            session->common.callbacks->connect_status_function(session->common.callbacks->userdata, status); \
    } while (0)

static int dh_handshake_server(ssh_session session);

/**
 * @addtogroup libssh_server
 *
 * @{
 */

/** @internal
 *
 * @brief initialize the set of key exchange, hostkey, ciphers, MACs, and
 *        compression algorithms for the given ssh_session
 *
 * The selection of algorithms and keys used are determined by the
 * options that are currently set in the given ssh_session structure.
 */

static int server_set_kex(ssh_session session) {
  struct ssh_kex_struct *server = &session->next_crypto->server_kex;
  int i, j, rc;
  const char *wanted;
  char hostkeys[128] = {0};
  enum ssh_keytypes_e keytype;
  size_t len;
  int ok;

  ZERO_STRUCTP(server);

  ok = ssh_get_random(server->cookie, 16, 0);
  if (!ok) {
      ssh_set_error(session, SSH_FATAL, "PRNG error");
      return -1;
  }

  if (session->srv.ed25519_key != NULL) {
      snprintf(hostkeys,
               sizeof(hostkeys),
               "%s",
               ssh_key_type_to_char(ssh_key_type(session->srv.ed25519_key)));
  }
#ifdef HAVE_ECC
  if (session->srv.ecdsa_key != NULL) {
	  len = strlen(hostkeys);
      snprintf(hostkeys + len, sizeof(hostkeys) - len,
               ",%s", session->srv.ecdsa_key->type_c);
  }
#endif
#ifdef HAVE_DSA
  if (session->srv.dsa_key != NULL) {
      len = strlen(hostkeys);
      keytype = ssh_key_type(session->srv.dsa_key);

      snprintf(hostkeys + len, sizeof(hostkeys) - len,
               ",%s", ssh_key_type_to_char(keytype));
  }
#endif
  if (session->srv.rsa_key != NULL) {
      /* We support also the SHA2 variants */
      len = strlen(hostkeys);
      snprintf(hostkeys + len, sizeof(hostkeys) - len,
               ",rsa-sha2-512,rsa-sha2-256");

      len = strlen(hostkeys);
      keytype = ssh_key_type(session->srv.rsa_key);

      snprintf(hostkeys + len, sizeof(hostkeys) - len,
               ",%s", ssh_key_type_to_char(keytype));
  }

  if (strlen(hostkeys) == 0) {
      return -1;
  }

  rc = ssh_options_set_algo(session,
                            SSH_HOSTKEYS,
                            hostkeys[0] == ',' ? hostkeys + 1 : hostkeys);
  if (rc < 0) {
      return -1;
  }

  for (i = 0; i < 10; i++) {
    if ((wanted = session->opts.wanted_methods[i]) == NULL) {
      wanted = ssh_kex_get_supported_method(i);
    }
    server->methods[i] = strdup(wanted);
    if (server->methods[i] == NULL) {
      for (j = 0; j < i; j++) {
        SAFE_FREE(server->methods[j]);
      }
      return -1;
    }
  }

  return 0;
}

int ssh_server_init_kex(ssh_session session) {
    int i;

    if (session->session_state > SSH_SESSION_STATE_BANNER_RECEIVED) {
        return SSH_ERROR;
    }

    /* free any currently-set methods: server_set_kex will allocate new ones */
    for (i = 0; i < 10 /* SSH_KEX_METHODS */; i++) {
        SAFE_FREE(session->next_crypto->server_kex.methods[i]);
    }

    return server_set_kex(session);
}

/** @internal
 * @brief parse an incoming SSH_MSG_KEXDH_INIT packet and complete
 *        key exchange
 **/
static int ssh_server_kexdh_init(ssh_session session, ssh_buffer packet){
    ssh_string e;
    e = ssh_buffer_get_ssh_string(packet);
    if (e == NULL) {
      ssh_set_error(session, SSH_FATAL, "No e number in client request");
      return -1;
    }
    if (ssh_dh_import_e(session, e) < 0) {
      ssh_set_error(session, SSH_FATAL, "Cannot import e number");
      session->session_state=SSH_SESSION_STATE_ERROR;
    } else {
      session->dh_handshake_state=DH_STATE_INIT_SENT;
      dh_handshake_server(session);
    }
    ssh_string_free(e);
    return SSH_OK;
}

static int ssh_server_send_extensions(ssh_session session) {
    int rc;
    const char *hostkey_algorithms;

    SSH_LOG(SSH_LOG_PACKET, "Sending SSH_MSG_EXT_INFO");
    /*
     * We can list here all the default hostkey methods, since
     * they already contain the SHA2 extension algorithms
     */
    hostkey_algorithms = ssh_kex_get_default_methods(SSH_HOSTKEYS);
    rc = ssh_buffer_pack(session->out_buffer,
                         "bdss",
                         SSH2_MSG_EXT_INFO,
                         1, /* nr. of extensions */
                         "server-sig-algs",
                         hostkey_algorithms);
    if (rc != SSH_OK) {
        goto error;
    }

    if (ssh_packet_send(session) == SSH_ERROR) {
        goto error;
    }

    return 0;
error:
    ssh_buffer_reinit(session->out_buffer);

    return -1;
}

SSH_PACKET_CALLBACK(ssh_packet_kexdh_init){
  int rc = SSH_ERROR;
  (void)type;
  (void)user;

  SSH_LOG(SSH_LOG_PACKET,"Received SSH_MSG_KEXDH_INIT");
  if(session->dh_handshake_state != DH_STATE_INIT){
    SSH_LOG(SSH_LOG_RARE,"Invalid state for SSH_MSG_KEXDH_INIT");
    goto error;
  }

  /* If first_kex_packet_follows guess was wrong, ignore this message. */
  if (session->first_kex_follows_guess_wrong != 0) {
    SSH_LOG(SSH_LOG_RARE, "first_kex_packet_follows guess was wrong, "
                          "ignoring first SSH_MSG_KEXDH_INIT message");
    session->first_kex_follows_guess_wrong = 0;
    rc = SSH_OK;
    goto error;
  }

  switch(session->next_crypto->kex_type){
      case SSH_KEX_DH_GROUP1_SHA1:
      case SSH_KEX_DH_GROUP14_SHA1:
      case SSH_KEX_DH_GROUP16_SHA512:
      case SSH_KEX_DH_GROUP18_SHA512:
        rc=ssh_server_kexdh_init(session, packet);
        break;
  #ifdef HAVE_ECDH
      case SSH_KEX_ECDH_SHA2_NISTP256:
      case SSH_KEX_ECDH_SHA2_NISTP384:
      case SSH_KEX_ECDH_SHA2_NISTP521:
        rc = ssh_server_ecdh_init(session, packet);
        break;
  #endif
  #ifdef HAVE_CURVE25519
      case SSH_KEX_CURVE25519_SHA256:
      case SSH_KEX_CURVE25519_SHA256_LIBSSH_ORG:
    	rc = ssh_server_curve25519_init(session, packet);
    	break;
  #endif
      default:
        ssh_set_error(session,SSH_FATAL,"Wrong kex type in ssh_packet_kexdh_init");
        rc = SSH_ERROR;
  }

error:
  if (rc == SSH_ERROR) {
      session->session_state = SSH_SESSION_STATE_ERROR;
  }

  return SSH_PACKET_USED;
}

int ssh_get_key_params(ssh_session session, ssh_key *privkey){
    ssh_key pubkey;
    ssh_string pubkey_blob;
    int rc;

    switch(session->srv.hostkey) {
      case SSH_KEYTYPE_DSS:
        *privkey = session->srv.dsa_key;
        break;
      case SSH_KEYTYPE_RSA:
        *privkey = session->srv.rsa_key;
        break;
      case SSH_KEYTYPE_ECDSA:
        *privkey = session->srv.ecdsa_key;
        break;
      case SSH_KEYTYPE_ED25519:
        *privkey = session->srv.ed25519_key;
        break;
      case SSH_KEYTYPE_RSA1:
      case SSH_KEYTYPE_UNKNOWN:
      default:
        *privkey = NULL;
    }

    rc = ssh_pki_export_privkey_to_pubkey(*privkey, &pubkey);
    if (rc < 0) {
      ssh_set_error(session, SSH_FATAL,
          "Could not get the public key from the private key");

      return -1;
    }

    rc = ssh_pki_export_pubkey_blob(pubkey, &pubkey_blob);
    ssh_key_free(pubkey);
    if (rc < 0) {
      ssh_set_error_oom(session);
      return -1;
    }

    rc = ssh_dh_import_next_pubkey_blob(session, pubkey_blob);
    ssh_string_free(pubkey_blob);
    if (rc != 0) {
        ssh_set_error(session,
                      SSH_FATAL,
                      "Could not import server public key");
        return -1;
    }

    return SSH_OK;
}

static int dh_handshake_server(ssh_session session) {
  ssh_key privkey;
  ssh_string sig_blob;
  ssh_string f;
  ssh_string pubkey_blob = NULL;
  int rc;

  if (ssh_dh_generate_y(session) < 0) {
    ssh_set_error(session, SSH_FATAL, "Could not create y number");
    return -1;
  }
  if (ssh_dh_generate_f(session) < 0) {
    ssh_set_error(session, SSH_FATAL, "Could not create f number");
    return -1;
  }

  f = ssh_dh_get_f(session);
  if (f == NULL) {
    ssh_set_error(session, SSH_FATAL, "Could not get the f number");
    return -1;
  }

  if (ssh_get_key_params(session,&privkey) != SSH_OK){
      ssh_string_free(f);
      return -1;
  }

  if (ssh_dh_build_k(session) < 0) {
    ssh_set_error(session, SSH_FATAL, "Could not import the public key");
    ssh_string_free(f);
    return -1;
  }

  if (ssh_make_sessionid(session) != SSH_OK) {
    ssh_set_error(session, SSH_FATAL, "Could not create a session id");
    ssh_string_free(f);
    return -1;
  }

  sig_blob = ssh_srv_pki_do_sign_sessionid(session, privkey);
  if (sig_blob == NULL) {
    ssh_set_error(session, SSH_FATAL, "Could not sign the session id");
    ssh_string_free(f);
    return -1;
  }

  rc = ssh_dh_get_next_server_publickey_blob(session, &pubkey_blob);
  if (rc != SSH_OK) {
      ssh_set_error_oom(session);
      ssh_string_free(f);
      ssh_string_free(sig_blob);
      return -1;
  }

  rc = ssh_buffer_pack(session->out_buffer,
                       "bSSS",
                       SSH2_MSG_KEXDH_REPLY,
                       pubkey_blob,
                       f,
                       sig_blob);
  ssh_string_free(f);
  ssh_string_free(sig_blob);
  ssh_string_free(pubkey_blob);
  if(rc != SSH_OK){
    ssh_set_error_oom(session);
    ssh_buffer_reinit(session->out_buffer);
    return -1;
  }

  if (ssh_packet_send(session) == SSH_ERROR) {
    return -1;
  }

  if (ssh_buffer_add_u8(session->out_buffer, SSH2_MSG_NEWKEYS) < 0) {
    ssh_buffer_reinit(session->out_buffer);
    return -1;
  }

  if (ssh_packet_send(session) == SSH_ERROR) {
    return -1;
  }
  SSH_LOG(SSH_LOG_PACKET, "SSH_MSG_NEWKEYS sent");
  session->dh_handshake_state=DH_STATE_NEWKEYS_SENT;

  return 0;
}

/**
 * @internal
 *
 * @brief A function to be called each time a step has been done in the
 * connection.
 */
static void ssh_server_connection_callback(ssh_session session){
    int rc;

    switch(session->session_state){
        case SSH_SESSION_STATE_NONE:
        case SSH_SESSION_STATE_CONNECTING:
        case SSH_SESSION_STATE_SOCKET_CONNECTED:
            break;
        case SSH_SESSION_STATE_BANNER_RECEIVED:
            if (session->clientbanner == NULL) {
                goto error;
            }
            set_status(session, 0.4f);
            SSH_LOG(SSH_LOG_RARE,
                    "SSH client banner: %s", session->clientbanner);

            /* Here we analyze the different protocols the server allows. */
            rc = ssh_analyze_banner(session, 1);
            if (rc < 0) {
                ssh_set_error(session, SSH_FATAL,
                        "No version of SSH protocol usable (banner: %s)",
                        session->clientbanner);
                goto error;
            }

            /* from now, the packet layer is handling incoming packets */
            session->socket_callbacks.data=ssh_packet_socket_callback;
            ssh_packet_register_socket_callback(session, session->socket);

            ssh_packet_set_default_callbacks(session);
            set_status(session, 0.5f);
            session->session_state=SSH_SESSION_STATE_INITIAL_KEX;
            if (ssh_send_kex(session, 1) < 0) {
                goto error;
            }
            break;
        case SSH_SESSION_STATE_INITIAL_KEX:
            /* TODO: This state should disappear in favor of get_key handle */
            break;
        case SSH_SESSION_STATE_KEXINIT_RECEIVED:
            set_status(session,0.6f);
            if(session->next_crypto->server_kex.methods[0]==NULL){
                if(server_set_kex(session) == SSH_ERROR)
                    goto error;
                /* We are in a rekeying, so we need to send the server kex */
                if(ssh_send_kex(session, 1) < 0)
                    goto error;
            }
            ssh_list_kex(&session->next_crypto->client_kex); // log client kex
            if (ssh_kex_select_methods(session) < 0) {
                goto error;
            }
            if (crypt_set_algorithms_server(session) == SSH_ERROR)
                goto error;
            set_status(session,0.8f);
            session->session_state=SSH_SESSION_STATE_DH;
            break;
        case SSH_SESSION_STATE_DH:
            if(session->dh_handshake_state==DH_STATE_FINISHED){
                if (ssh_generate_session_keys(session) < 0) {
                    goto error;
                }

                /*
                 * Once we got SSH2_MSG_NEWKEYS we can switch next_crypto and
                 * current_crypto
                 */
                if (session->current_crypto) {
                    crypto_free(session->current_crypto);
                }

                /* FIXME TODO later, include a function to change keys */
                session->current_crypto = session->next_crypto;
                session->next_crypto = crypto_new();
                if (session->next_crypto == NULL) {
                    goto error;
                }
                session->next_crypto->session_id = malloc(session->current_crypto->digest_len);
                if (session->next_crypto->session_id == NULL) {
                    ssh_set_error_oom(session);
                    goto error;
                }
                memcpy(session->next_crypto->session_id, session->current_crypto->session_id,
                        session->current_crypto->digest_len);
                if (session->current_crypto->in_cipher->set_decrypt_key(session->current_crypto->in_cipher, session->current_crypto->decryptkey,
                            session->current_crypto->decryptIV) < 0) {
                    goto error;
                }
                if (session->current_crypto->out_cipher->set_encrypt_key(session->current_crypto->out_cipher, session->current_crypto->encryptkey,
                            session->current_crypto->encryptIV) < 0) {
                    goto error;
                }

                /*
                 * If the client supports extension negotiation, we will send
                 * our supported extensions now. This is the first message after
                 * sending NEWKEYS message and after turning on crypto.
                 */
                if (session->extensions & SSH_EXT_NEGOTIATION &&
                    session->session_state != SSH_SESSION_STATE_AUTHENTICATED) {
                    ssh_server_send_extensions(session);
                }

                set_status(session,1.0f);
                session->connected = 1;
                session->session_state=SSH_SESSION_STATE_AUTHENTICATING;
                if (session->flags & SSH_SESSION_FLAG_AUTHENTICATED)
                    session->session_state = SSH_SESSION_STATE_AUTHENTICATED;

            }
            break;
        case SSH_SESSION_STATE_AUTHENTICATING:
            break;
        case SSH_SESSION_STATE_ERROR:
            goto error;
        default:
            ssh_set_error(session,SSH_FATAL,"Invalid state %d",session->session_state);
    }

    return;
error:
    ssh_socket_close(session->socket);
    session->alive = 0;
    session->session_state=SSH_SESSION_STATE_ERROR;
}

/**
 * @internal
 *
 * @brief Gets the banner from socket and saves it in session.
 * Updates the session state
 *
 * @param  data pointer to the beginning of header
 * @param  len size of the banner
 * @param  user is a pointer to session
 * @returns Number of bytes processed, or zero if the banner is not complete.
 */
static int callback_receive_banner(const void *data, size_t len, void *user) {
    char *buffer = (char *) data;
    ssh_session session = (ssh_session) user;
    char *str = NULL;
    size_t i;
    int ret=0;

    for (i = 0; i < len; i++) {
#ifdef WITH_PCAP
        if(session->pcap_ctx && buffer[i] == '\n') {
            ssh_pcap_context_write(session->pcap_ctx,
                                   SSH_PCAP_DIR_IN,
                                   buffer,
                                   i + 1,
                                   i + 1);
        }
#endif
        if (buffer[i] == '\r') {
            buffer[i]='\0';
        }

        if (buffer[i] == '\n') {
            buffer[i]='\0';

            str = strdup(buffer);
            /* number of bytes read */
            ret = i + 1;
            session->clientbanner = str;
            session->session_state = SSH_SESSION_STATE_BANNER_RECEIVED;
            SSH_LOG(SSH_LOG_PACKET, "Received banner: %s", str);
            session->ssh_connection_callback(session);

            return ret;
        }

        if(i > 127) {
            /* Too big banner */
            session->session_state = SSH_SESSION_STATE_ERROR;
            ssh_set_error(session, SSH_FATAL, "Receiving banner: too large banner");

            return 0;
        }
    }

    return ret;
}

/* returns 0 until the key exchange is not finished */
static int ssh_server_kex_termination(void *s){
  ssh_session session = s;
  if (session->session_state != SSH_SESSION_STATE_ERROR &&
      session->session_state != SSH_SESSION_STATE_AUTHENTICATING &&
      session->session_state != SSH_SESSION_STATE_DISCONNECTED)
    return 0;
  else
    return 1;
}

void ssh_set_auth_methods(ssh_session session, int auth_methods){
	/* accept only methods in range */
    session->auth.supported_methods = auth_methods & 0x3f;
}

/* Do the banner and key exchange */
int ssh_handle_key_exchange(ssh_session session) {
    int rc;
    if (session->session_state != SSH_SESSION_STATE_NONE)
      goto pending;
    rc = ssh_send_banner(session, 1);
    if (rc < 0) {
        return SSH_ERROR;
    }

    session->alive = 1;

    session->ssh_connection_callback = ssh_server_connection_callback;
    session->session_state = SSH_SESSION_STATE_SOCKET_CONNECTED;
    ssh_socket_set_callbacks(session->socket,&session->socket_callbacks);
    session->socket_callbacks.data=callback_receive_banner;
    session->socket_callbacks.exception=ssh_socket_exception_callback;
    session->socket_callbacks.userdata=session;

    rc = server_set_kex(session);
    if (rc < 0) {
        return SSH_ERROR;
    }
    pending:
    rc = ssh_handle_packets_termination(session, SSH_TIMEOUT_USER,
        ssh_server_kex_termination,session);
    SSH_LOG(SSH_LOG_PACKET, "ssh_handle_key_exchange: current state : %d",
        session->session_state);
    if (rc != SSH_OK)
      return rc;
    if (session->session_state == SSH_SESSION_STATE_ERROR ||
        session->session_state == SSH_SESSION_STATE_DISCONNECTED) {
      return SSH_ERROR;
    }

  return SSH_OK;
}

/* messages */

/** @internal
 * replies to an SSH_AUTH packet with a default (denied) response.
 */
int ssh_auth_reply_default(ssh_session session,int partial) {
  char methods_c[128] = {0};
  int rc = SSH_ERROR;


  if (session->auth.supported_methods == 0) {
    session->auth.supported_methods = SSH_AUTH_METHOD_PUBLICKEY | SSH_AUTH_METHOD_PASSWORD;
  }
  if (session->auth.supported_methods & SSH_AUTH_METHOD_PUBLICKEY) {
    strncat(methods_c, "publickey,",
            sizeof(methods_c) - strlen(methods_c) - 1);
  }
  if (session->auth.supported_methods & SSH_AUTH_METHOD_GSSAPI_MIC){
	  strncat(methods_c,"gssapi-with-mic,",
			  sizeof(methods_c) - strlen(methods_c) - 1);
  }
  if (session->auth.supported_methods & SSH_AUTH_METHOD_INTERACTIVE) {
    strncat(methods_c, "keyboard-interactive,",
            sizeof(methods_c) - strlen(methods_c) - 1);
  }
  if (session->auth.supported_methods & SSH_AUTH_METHOD_PASSWORD) {
    strncat(methods_c, "password,",
            sizeof(methods_c) - strlen(methods_c) - 1);
  }
  if (session->auth.supported_methods & SSH_AUTH_METHOD_HOSTBASED) {
    strncat(methods_c, "hostbased,",
            sizeof(methods_c) - strlen(methods_c) - 1);
  }

  if (methods_c[0] == '\0' || methods_c[strlen(methods_c)-1] != ',') {
      return SSH_ERROR;
  }

  /* Strip the comma. */
  methods_c[strlen(methods_c) - 1] = '\0'; // strip the comma. We are sure there is at

  SSH_LOG(SSH_LOG_PACKET,
      "Sending a auth failure. methods that can continue: %s", methods_c);

  rc = ssh_buffer_pack(session->out_buffer,
                       "bsb",
                       SSH2_MSG_USERAUTH_FAILURE,
                       methods_c,
                       partial ? 1 : 0);
  if (rc != SSH_OK){
      ssh_set_error_oom(session);
      return SSH_ERROR;
  }
  rc = ssh_packet_send(session);
  return rc;
}

static int ssh_message_channel_request_open_reply_default(ssh_message msg) {
    int rc;

    SSH_LOG(SSH_LOG_FUNCTIONS, "Refusing a channel");

    rc = ssh_buffer_pack(msg->session->out_buffer,
                         "bdddd",
                         SSH2_MSG_CHANNEL_OPEN_FAILURE,
                         msg->channel_request_open.sender,
                         SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED,
                         0,    /* reason is empty string */
                         0);   /* language string */
    if (rc != SSH_OK){
        ssh_set_error_oom(msg->session);
        return SSH_ERROR;
    }

    rc = ssh_packet_send(msg->session);
    return rc;
}

static int ssh_message_channel_request_reply_default(ssh_message msg) {
  uint32_t channel;
  int rc;

  if (msg->channel_request.want_reply) {
    channel = msg->channel_request.channel->remote_channel;

    SSH_LOG(SSH_LOG_PACKET,
        "Sending a default channel_request denied to channel %d", channel);

    rc = ssh_buffer_pack(msg->session->out_buffer,
                         "bd",
                         SSH2_MSG_CHANNEL_FAILURE,
                         channel);
    if (rc != SSH_OK){
        ssh_set_error_oom(msg->session);
        return SSH_ERROR;
    }
    return ssh_packet_send(msg->session);
  }

  SSH_LOG(SSH_LOG_PACKET,
      "The client doesn't want to know the request failed!");

  return SSH_OK;
}

static int ssh_message_service_request_reply_default(ssh_message msg) {
  /* The only return code accepted by specifications are success or disconnect */
  return ssh_message_service_reply_success(msg);
}

int ssh_message_service_reply_success(ssh_message msg) {
    ssh_session session;
    int rc;

    if (msg == NULL) {
        return SSH_ERROR;
    }
    session = msg->session;

    SSH_LOG(SSH_LOG_PACKET,
            "Sending a SERVICE_ACCEPT for service %s", msg->service_request.service);

    rc = ssh_buffer_pack(session->out_buffer,
                         "bs",
                         SSH2_MSG_SERVICE_ACCEPT,
                         msg->service_request.service);
    if (rc != SSH_OK){
        ssh_set_error_oom(session);
        return SSH_ERROR;
    }
    rc = ssh_packet_send(msg->session);
    return rc;
}

int ssh_message_global_request_reply_success(ssh_message msg, uint16_t bound_port) {
    int rc;

    SSH_LOG(SSH_LOG_FUNCTIONS, "Accepting a global request");

    if (msg->global_request.want_reply) {
        if (ssh_buffer_add_u8(msg->session->out_buffer
                    , SSH2_MSG_REQUEST_SUCCESS) < 0) {
            goto error;
        }

        if(msg->global_request.type == SSH_GLOBAL_REQUEST_TCPIP_FORWARD 
                                && msg->global_request.bind_port == 0) {
            rc = ssh_buffer_pack(msg->session->out_buffer, "d", bound_port);
            if (rc != SSH_OK) {
                ssh_set_error_oom(msg->session);
                goto error;
            }
        }

        return ssh_packet_send(msg->session);
    }

    if(msg->global_request.type == SSH_GLOBAL_REQUEST_TCPIP_FORWARD 
                                && msg->global_request.bind_port == 0) {
        SSH_LOG(SSH_LOG_PACKET,
                "The client doesn't want to know the remote port!");
    }

    return SSH_OK;
error:
    return SSH_ERROR;
}

static int ssh_message_global_request_reply_default(ssh_message msg) {
    SSH_LOG(SSH_LOG_FUNCTIONS, "Refusing a global request");

    if (msg->global_request.want_reply) {
        if (ssh_buffer_add_u8(msg->session->out_buffer
                    , SSH2_MSG_REQUEST_FAILURE) < 0) {
            goto error;
        }
        return ssh_packet_send(msg->session);
    }
    SSH_LOG(SSH_LOG_PACKET,
            "The client doesn't want to know the request failed!");

    return SSH_OK;
error:
    return SSH_ERROR;
}

int ssh_message_reply_default(ssh_message msg) {
  if (msg == NULL) {
    return -1;
  }

  switch(msg->type) {
    case SSH_REQUEST_AUTH:
      return ssh_auth_reply_default(msg->session, 0);
    case SSH_REQUEST_CHANNEL_OPEN:
      return ssh_message_channel_request_open_reply_default(msg);
    case SSH_REQUEST_CHANNEL:
      return ssh_message_channel_request_reply_default(msg);
    case SSH_REQUEST_SERVICE:
      return ssh_message_service_request_reply_default(msg);
    case SSH_REQUEST_GLOBAL:
      return ssh_message_global_request_reply_default(msg);
    default:
      SSH_LOG(SSH_LOG_PACKET,
          "Don't know what to default reply to %d type",
          msg->type);
      break;
  }

  return -1;
}

const char *ssh_message_service_service(ssh_message msg){
  if (msg == NULL) {
    return NULL;
  }
  return msg->service_request.service;
}

const char *ssh_message_auth_user(ssh_message msg) {
  if (msg == NULL) {
    return NULL;
  }

  return msg->auth_request.username;
}

const char *ssh_message_auth_password(ssh_message msg){
  if (msg == NULL) {
    return NULL;
  }

  return msg->auth_request.password;
}

ssh_key ssh_message_auth_pubkey(ssh_message msg) {
  if (msg == NULL) {
    return NULL;
  }

  return msg->auth_request.pubkey;
}

/* Get the publickey of an auth request */
ssh_public_key ssh_message_auth_publickey(ssh_message msg){
  if (msg == NULL) {
    return NULL;
  }

  return ssh_pki_convert_key_to_publickey(msg->auth_request.pubkey);
}

enum ssh_publickey_state_e ssh_message_auth_publickey_state(ssh_message msg){
	if (msg == NULL) {
	    return -1;
	  }
	  return msg->auth_request.signature_state;
}

int ssh_message_auth_kbdint_is_response(ssh_message msg) {
  if (msg == NULL) {
    return -1;
  }

  return msg->auth_request.kbdint_response != 0;
}

int ssh_message_auth_set_methods(ssh_message msg, int methods) {
  if (msg == NULL || msg->session == NULL) {
    return -1;
  }

  msg->session->auth.supported_methods = methods;

  return 0;
}

int ssh_message_auth_interactive_request(ssh_message msg, const char *name,
                            const char *instruction, unsigned int num_prompts,
                            const char **prompts, char *echo) {
  int rc;
  unsigned int i = 0;

  if(name == NULL || instruction == NULL) {
    return SSH_ERROR;
  }
  if(num_prompts > 0 && (prompts == NULL || echo == NULL)) {
    return SSH_ERROR;
  }

  rc = ssh_buffer_pack(msg->session->out_buffer,
                       "bsssd",
                       SSH2_MSG_USERAUTH_INFO_REQUEST,
                       name,
                       instruction,
                       "",           /* language tag */
                       num_prompts);
  if (rc != SSH_OK){
    ssh_set_error_oom(msg->session);
    return SSH_ERROR;
  }

  for(i = 0; i < num_prompts; i++) {
    rc = ssh_buffer_pack(msg->session->out_buffer,
                         "sb",
                         prompts[i],
                         echo[i] ? 1 : 0);
    if (rc != SSH_OK){
        ssh_set_error_oom(msg->session);
        return SSH_ERROR;
    }
  }

  rc = ssh_packet_send(msg->session);

  /* fill in the kbdint structure */
  if (msg->session->kbdint == NULL) {
    SSH_LOG(SSH_LOG_PROTOCOL, "Warning: Got a "
                                        "keyboard-interactive response but it "
                                        "seems we didn't send the request.");

    msg->session->kbdint = ssh_kbdint_new();
    if (msg->session->kbdint == NULL) {
      ssh_set_error_oom(msg->session);

      return SSH_ERROR;
    }
  } else {
    ssh_kbdint_clean(msg->session->kbdint);
  }

  msg->session->kbdint->name = strdup(name);
  if(msg->session->kbdint->name == NULL) {
      ssh_set_error_oom(msg->session);
      ssh_kbdint_free(msg->session->kbdint);
      msg->session->kbdint = NULL;
      return SSH_PACKET_USED;
  }
  msg->session->kbdint->instruction = strdup(instruction);
  if(msg->session->kbdint->instruction == NULL) {
      ssh_set_error_oom(msg->session);
      ssh_kbdint_free(msg->session->kbdint);
      msg->session->kbdint = NULL;
      return SSH_PACKET_USED;
  }

  msg->session->kbdint->nprompts = num_prompts;
  if(num_prompts > 0) {
    msg->session->kbdint->prompts = calloc(num_prompts, sizeof(char *));
    if (msg->session->kbdint->prompts == NULL) {
      msg->session->kbdint->nprompts = 0;
      ssh_set_error_oom(msg->session);
      ssh_kbdint_free(msg->session->kbdint);
      msg->session->kbdint = NULL;
      return SSH_ERROR;
    }
    msg->session->kbdint->echo = calloc(num_prompts, sizeof(unsigned char));
    if (msg->session->kbdint->echo == NULL) {
      ssh_set_error_oom(msg->session);
      ssh_kbdint_free(msg->session->kbdint);
      msg->session->kbdint = NULL;
      return SSH_ERROR;
    }
    for (i = 0; i < num_prompts; i++) {
      msg->session->kbdint->echo[i] = echo[i];
      msg->session->kbdint->prompts[i] = strdup(prompts[i]);
      if (msg->session->kbdint->prompts[i] == NULL) {
        ssh_set_error_oom(msg->session);
        msg->session->kbdint->nprompts = i;
        ssh_kbdint_free(msg->session->kbdint);
        msg->session->kbdint = NULL;
        return SSH_PACKET_USED;
      }
    }
  } else {
    msg->session->kbdint->prompts = NULL;
    msg->session->kbdint->echo = NULL;
  }
  msg->session->auth.state = SSH_AUTH_STATE_INFO;

  return rc;
}

int ssh_auth_reply_success(ssh_session session, int partial) {
  int r;

  if (session == NULL) {
	  return SSH_ERROR;
  }

  if (partial) {
    return ssh_auth_reply_default(session, partial);
  }
  
  session->session_state = SSH_SESSION_STATE_AUTHENTICATED;
  session->flags |= SSH_SESSION_FLAG_AUTHENTICATED;

  if (ssh_buffer_add_u8(session->out_buffer,SSH2_MSG_USERAUTH_SUCCESS) < 0) {
    return SSH_ERROR;
  }

  r = ssh_packet_send(session);
  if(session->current_crypto && session->current_crypto->delayed_compress_out){
      SSH_LOG(SSH_LOG_PROTOCOL,"Enabling delayed compression OUT");
  	session->current_crypto->do_compress_out=1;
  }
  if(session->current_crypto && session->current_crypto->delayed_compress_in){
      SSH_LOG(SSH_LOG_PROTOCOL,"Enabling delayed compression IN");
  	session->current_crypto->do_compress_in=1;
  }
  return r;
}

int ssh_message_auth_reply_success(ssh_message msg, int partial) {
	if(msg == NULL)
		return SSH_ERROR;
	return ssh_auth_reply_success(msg->session, partial);
}

/* Answer OK to a pubkey auth request */
int ssh_message_auth_reply_pk_ok(ssh_message msg, ssh_string algo, ssh_string pubkey) {
    int rc;
    if (msg == NULL) {
        return SSH_ERROR;
    }

    rc = ssh_buffer_pack(msg->session->out_buffer,
                         "bSS",
                         SSH2_MSG_USERAUTH_PK_OK,
                         algo,
                         pubkey);
    if(rc != SSH_OK){
        ssh_set_error_oom(msg->session);
        return SSH_ERROR;
    }

    rc = ssh_packet_send(msg->session);
    return rc;
}

int ssh_message_auth_reply_pk_ok_simple(ssh_message msg) {
    ssh_string algo;
    ssh_string pubkey_blob = NULL;
    int ret;

    algo = ssh_string_from_char(msg->auth_request.pubkey->type_c);
    if (algo == NULL) {
        return SSH_ERROR;
    }

    ret = ssh_pki_export_pubkey_blob(msg->auth_request.pubkey, &pubkey_blob);
    if (ret < 0) {
        ssh_string_free(algo);
        return SSH_ERROR;
    }

    ret = ssh_message_auth_reply_pk_ok(msg, algo, pubkey_blob);

    ssh_string_free(algo);
    ssh_string_free(pubkey_blob);

    return ret;
}


const char *ssh_message_channel_request_open_originator(ssh_message msg){
    return msg->channel_request_open.originator;
}

int ssh_message_channel_request_open_originator_port(ssh_message msg){
    return msg->channel_request_open.originator_port;
}

const char *ssh_message_channel_request_open_destination(ssh_message msg){
    return msg->channel_request_open.destination;
}

int ssh_message_channel_request_open_destination_port(ssh_message msg){
    return msg->channel_request_open.destination_port;
}

ssh_channel ssh_message_channel_request_channel(ssh_message msg){
    return msg->channel_request.channel;
}

const char *ssh_message_channel_request_pty_term(ssh_message msg){
    return msg->channel_request.TERM;
}

int ssh_message_channel_request_pty_width(ssh_message msg){
    return msg->channel_request.width;
}

int ssh_message_channel_request_pty_height(ssh_message msg){
    return msg->channel_request.height;
}

int ssh_message_channel_request_pty_pxwidth(ssh_message msg){
    return msg->channel_request.pxwidth;
}

int ssh_message_channel_request_pty_pxheight(ssh_message msg){
    return msg->channel_request.pxheight;
}

const char *ssh_message_channel_request_env_name(ssh_message msg){
    return msg->channel_request.var_name;
}

const char *ssh_message_channel_request_env_value(ssh_message msg){
    return msg->channel_request.var_value;
}

const char *ssh_message_channel_request_command(ssh_message msg){
    return msg->channel_request.command;
}

const char *ssh_message_channel_request_subsystem(ssh_message msg){
    return msg->channel_request.subsystem;
}

int ssh_message_channel_request_x11_single_connection(ssh_message msg){
    return msg->channel_request.x11_single_connection ? 1 : 0;
}

const char *ssh_message_channel_request_x11_auth_protocol(ssh_message msg){
    return msg->channel_request.x11_auth_protocol;
}

const char *ssh_message_channel_request_x11_auth_cookie(ssh_message msg){
    return msg->channel_request.x11_auth_cookie;
}

int ssh_message_channel_request_x11_screen_number(ssh_message msg){
    return msg->channel_request.x11_screen_number;
}

const char *ssh_message_global_request_address(ssh_message msg){
    return msg->global_request.bind_address;
}

int ssh_message_global_request_port(ssh_message msg){
    return msg->global_request.bind_port;
}

/** @brief defines the ssh_message callback
 * @param session the current ssh session
 * @param[in] ssh_bind_message_callback a function pointer to a callback taking the
 * current ssh session and received message as parameters. the function returns
 * 0 if the message has been parsed and treated successfully, 1 otherwise (libssh
 * must take care of the response).
 * @param[in] data void pointer to be passed to callback functions
 */
void ssh_set_message_callback(ssh_session session,
        int(*ssh_bind_message_callback)(ssh_session session, ssh_message msg, void *data),
        void *data) {
  session->ssh_message_callback = ssh_bind_message_callback;
  session->ssh_message_callback_data = data;
}

int ssh_execute_message_callbacks(ssh_session session){
  ssh_message msg=NULL;
  int ret;
  ssh_handle_packets(session, SSH_TIMEOUT_NONBLOCKING);
  if(!session->ssh_message_list)
    return SSH_OK;
  if(session->ssh_message_callback){
    while((msg=ssh_message_pop_head(session)) != NULL) {
      ret=session->ssh_message_callback(session,msg,
                                        session->ssh_message_callback_data);
      if(ret==1){
        ret = ssh_message_reply_default(msg);
        ssh_message_free(msg);
        if(ret != SSH_OK)
          return ret;
      } else {
        ssh_message_free(msg);
      }
    }
  } else {
    while((msg=ssh_message_pop_head(session)) != NULL) {
      ret = ssh_message_reply_default(msg);
      ssh_message_free(msg);
      if(ret != SSH_OK)
        return ret;
    }
  }
  return SSH_OK;
}

int ssh_send_keepalive(ssh_session session)
{
    /* Client denies the request, so the error code is not meaningful */
    (void)ssh_global_request(session, "keepalive@openssh.com", NULL, 1);

    return SSH_OK;
}

/** @} */