ssh.c

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2011, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at http://curl.haxx.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ***************************************************************************/

/* #define CURL_LIBSSH2_DEBUG */

#include "setup.h"

#ifdef USE_LIBSSH2
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdarg.h>
#include <ctype.h>
#ifdef HAVE_LIMITS_H
#  include <limits.h>
#endif

#include <libssh2.h>
#include <libssh2_sftp.h>

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif

#ifdef HAVE_TIME_H
#include <time.h>
#endif

#ifndef WIN32
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
#ifdef HAVE_UTSNAME_H
#include <sys/utsname.h>
#endif
#ifdef HAVE_NETDB_H
#include <netdb.h>
#endif
#ifdef __VMS
#include <in.h>
#include <inet.h>
#endif
#endif /* !WIN32 */

#if (defined(NETWARE) && defined(__NOVELL_LIBC__))
#undef in_addr_t
#define in_addr_t unsigned long
#endif

#include <curl/curl.h>
#include "urldata.h"
#include "sendf.h"
#include "easyif.h" /* for Curl_convert_... prototypes */

#include "hostip.h"
#include "progress.h"
#include "transfer.h"
#include "escape.h"
#include "http.h" /* for HTTP proxy tunnel stuff */
#include "ssh.h"
#include "url.h"
#include "speedcheck.h"
#include "getinfo.h"

#include "strequal.h"
#include "sslgen.h"
#include "connect.h"
#include "strerror.h"
#include "inet_ntop.h"
#include "parsedate.h" /* for the week day and month names */
#include "sockaddr.h" /* required for Curl_sockaddr_storage */
#include "strtoofft.h"
#include "multiif.h"
#include "select.h"
#include "warnless.h"

#define _MPRINTF_REPLACE /* use our functions only */
#include <curl/mprintf.h>

#include "curl_memory.h"
/* The last #include file should be: */
#include "memdebug.h"

#ifndef PATH_MAX
#define PATH_MAX 1024 /* just an extra precaution since there are systems that
                         have their definition hidden well */
#endif

/* Local functions: */
static const char *sftp_libssh2_strerror(unsigned long err);
static LIBSSH2_ALLOC_FUNC(my_libssh2_malloc);
static LIBSSH2_REALLOC_FUNC(my_libssh2_realloc);
static LIBSSH2_FREE_FUNC(my_libssh2_free);

static CURLcode get_pathname(const char **cpp, char **path);

static CURLcode ssh_connect(struct connectdata *conn, bool *done);
static CURLcode ssh_multi_statemach(struct connectdata *conn, bool *done);
static CURLcode ssh_do(struct connectdata *conn, bool *done);

static CURLcode ssh_getworkingpath(struct connectdata *conn,
                                   char *homedir, /* when SFTP is used */
                                   char **path);

static CURLcode scp_done(struct connectdata *conn,
                         CURLcode, bool premature);
static CURLcode scp_doing(struct connectdata *conn,
                          bool *dophase_done);
static CURLcode scp_disconnect(struct connectdata *conn, bool dead_connection);

static CURLcode sftp_done(struct connectdata *conn,
                          CURLcode, bool premature);
static CURLcode sftp_doing(struct connectdata *conn,
                           bool *dophase_done);
static CURLcode sftp_disconnect(struct connectdata *conn, bool dead_connection);
static
CURLcode sftp_perform(struct connectdata *conn,
                      bool *connected,
                      bool *dophase_done);

static int ssh_getsock(struct connectdata *conn,
                       curl_socket_t *sock, /* points to numsocks number
                                               of sockets */
                       int numsocks);

static int ssh_perform_getsock(const struct connectdata *conn,
                               curl_socket_t *sock, /* points to numsocks
                                                       number of sockets */
                               int numsocks);

/*
 * SCP protocol handler.
 */

const struct Curl_handler Curl_handler_scp = {
  "SCP",                                /* scheme */
  ZERO_NULL,                            /* setup_connection */
  ssh_do,                               /* do_it */
  scp_done,                             /* done */
  ZERO_NULL,                            /* do_more */
  ssh_connect,                          /* connect_it */
  ssh_multi_statemach,                  /* connecting */
  scp_doing,                            /* doing */
  ssh_getsock,                          /* proto_getsock */
  ssh_getsock,                          /* doing_getsock */
  ssh_perform_getsock,                  /* perform_getsock */
  scp_disconnect,                       /* disconnect */
  PORT_SSH,                             /* defport */
  PROT_SCP                              /* protocol */
};


/*
 * SFTP protocol handler.
 */

const struct Curl_handler Curl_handler_sftp = {
  "SFTP",                               /* scheme */
  ZERO_NULL,                            /* setup_connection */
  ssh_do,                               /* do_it */
  sftp_done,                            /* done */
  ZERO_NULL,                            /* do_more */
  ssh_connect,                          /* connect_it */
  ssh_multi_statemach,                  /* connecting */
  sftp_doing,                           /* doing */
  ssh_getsock,                          /* proto_getsock */
  ssh_getsock,                          /* doing_getsock */
  ssh_perform_getsock,                  /* perform_getsock */
  sftp_disconnect,                      /* disconnect */
  PORT_SSH,                             /* defport */
  PROT_SFTP                             /* protocol */
};


static void
kbd_callback(const char *name, int name_len, const char *instruction,
             int instruction_len, int num_prompts,
             const LIBSSH2_USERAUTH_KBDINT_PROMPT *prompts,
             LIBSSH2_USERAUTH_KBDINT_RESPONSE *responses,
             void **abstract)
{
  struct connectdata *conn = (struct connectdata *)*abstract;

#ifdef CURL_LIBSSH2_DEBUG
  fprintf(stderr, "name=%s\n", name);
  fprintf(stderr, "name_len=%d\n", name_len);
  fprintf(stderr, "instruction=%s\n", instruction);
  fprintf(stderr, "instruction_len=%d\n", instruction_len);
  fprintf(stderr, "num_prompts=%d\n", num_prompts);
#else
  (void)name;
  (void)name_len;
  (void)instruction;
  (void)instruction_len;
#endif  /* CURL_LIBSSH2_DEBUG */
  if(num_prompts == 1) {
    responses[0].text = strdup(conn->passwd);
    responses[0].length = (unsigned int)strlen(conn->passwd);
  }
  (void)prompts;
  (void)abstract;
} /* kbd_callback */

static CURLcode sftp_libssh2_error_to_CURLE(int err)
{
  switch (err) {
    case LIBSSH2_FX_OK:
      return CURLE_OK;

    case LIBSSH2_FX_NO_SUCH_FILE:
    case LIBSSH2_FX_NO_SUCH_PATH:
      return CURLE_REMOTE_FILE_NOT_FOUND;

    case LIBSSH2_FX_PERMISSION_DENIED:
    case LIBSSH2_FX_WRITE_PROTECT:
    case LIBSSH2_FX_LOCK_CONFlICT:
      return CURLE_REMOTE_ACCESS_DENIED;

    case LIBSSH2_FX_NO_SPACE_ON_FILESYSTEM:
    case LIBSSH2_FX_QUOTA_EXCEEDED:
      return CURLE_REMOTE_DISK_FULL;

    case LIBSSH2_FX_FILE_ALREADY_EXISTS:
      return CURLE_REMOTE_FILE_EXISTS;

    case LIBSSH2_FX_DIR_NOT_EMPTY:
      return CURLE_QUOTE_ERROR;

    default:
      break;
  }

  return CURLE_SSH;
}

static CURLcode libssh2_session_error_to_CURLE(int err)
{
  switch (err) {
    /* Ordered by order of appearance in libssh2.h */
    case LIBSSH2_ERROR_NONE:
      return CURLE_OK;

    case LIBSSH2_ERROR_SOCKET_NONE:
      return CURLE_COULDNT_CONNECT;

    case LIBSSH2_ERROR_ALLOC:
      return CURLE_OUT_OF_MEMORY;

    case LIBSSH2_ERROR_SOCKET_SEND:
      return CURLE_SEND_ERROR;

    case LIBSSH2_ERROR_HOSTKEY_INIT:
    case LIBSSH2_ERROR_HOSTKEY_SIGN:
    case LIBSSH2_ERROR_PUBLICKEY_UNRECOGNIZED:
    case LIBSSH2_ERROR_PUBLICKEY_UNVERIFIED:
      return CURLE_PEER_FAILED_VERIFICATION;

    case LIBSSH2_ERROR_PASSWORD_EXPIRED:
      return CURLE_LOGIN_DENIED;

    case LIBSSH2_ERROR_SOCKET_TIMEOUT:
    case LIBSSH2_ERROR_TIMEOUT:
      return CURLE_OPERATION_TIMEDOUT;

    case LIBSSH2_ERROR_EAGAIN:
      return CURLE_AGAIN;
  }

  /* TODO: map some more of the libssh2 errors to the more appropriate CURLcode
     error code, and possibly add a few new SSH-related one. We must however
     not return or even depend on libssh2 errors in the public libcurl API */

  return CURLE_SSH;
}

static LIBSSH2_ALLOC_FUNC(my_libssh2_malloc)
{
  (void)abstract; /* arg not used */
  return malloc(count);
}

static LIBSSH2_REALLOC_FUNC(my_libssh2_realloc)
{
  (void)abstract; /* arg not used */
  return realloc(ptr, count);
}

static LIBSSH2_FREE_FUNC(my_libssh2_free)
{
  (void)abstract; /* arg not used */
  free(ptr);
}

/*
 * SSH State machine related code
 */
/* This is the ONLY way to change SSH state! */
static void state(struct connectdata *conn, sshstate nowstate)
{
#if defined(DEBUGBUILD) && !defined(CURL_DISABLE_VERBOSE_STRINGS)
  /* for debug purposes */
  static const char * const names[] = {
    "SSH_STOP",
    "SSH_S_STARTUP",
    "SSH_HOSTKEY",
    "SSH_AUTHLIST",
    "SSH_AUTH_PKEY_INIT",
    "SSH_AUTH_PKEY",
    "SSH_AUTH_PASS_INIT",
    "SSH_AUTH_PASS",
    "SSH_AUTH_HOST_INIT",
    "SSH_AUTH_HOST",
    "SSH_AUTH_KEY_INIT",
    "SSH_AUTH_KEY",
    "SSH_AUTH_DONE",
    "SSH_SFTP_INIT",
    "SSH_SFTP_REALPATH",
    "SSH_SFTP_QUOTE_INIT",
    "SSH_SFTP_POSTQUOTE_INIT",
    "SSH_SFTP_QUOTE",
    "SSH_SFTP_NEXT_QUOTE",
    "SSH_SFTP_QUOTE_STAT",
    "SSH_SFTP_QUOTE_SETSTAT",
    "SSH_SFTP_QUOTE_SYMLINK",
    "SSH_SFTP_QUOTE_MKDIR",
    "SSH_SFTP_QUOTE_RENAME",
    "SSH_SFTP_QUOTE_RMDIR",
    "SSH_SFTP_QUOTE_UNLINK",
    "SSH_SFTP_TRANS_INIT",
    "SSH_SFTP_UPLOAD_INIT",
    "SSH_SFTP_CREATE_DIRS_INIT",
    "SSH_SFTP_CREATE_DIRS",
    "SSH_SFTP_CREATE_DIRS_MKDIR",
    "SSH_SFTP_READDIR_INIT",
    "SSH_SFTP_READDIR",
    "SSH_SFTP_READDIR_LINK",
    "SSH_SFTP_READDIR_BOTTOM",
    "SSH_SFTP_READDIR_DONE",
    "SSH_SFTP_DOWNLOAD_INIT",
    "SSH_SFTP_DOWNLOAD_STAT",
    "SSH_SFTP_CLOSE",
    "SSH_SFTP_SHUTDOWN",
    "SSH_SCP_TRANS_INIT",
    "SSH_SCP_UPLOAD_INIT",
    "SSH_SCP_DOWNLOAD_INIT",
    "SSH_SCP_DONE",
    "SSH_SCP_SEND_EOF",
    "SSH_SCP_WAIT_EOF",
    "SSH_SCP_WAIT_CLOSE",
    "SSH_SCP_CHANNEL_FREE",
    "SSH_SESSION_DISCONNECT",
    "SSH_SESSION_FREE",
    "QUIT"
  };
#endif
  struct ssh_conn *sshc = &conn->proto.sshc;

#if defined(DEBUGBUILD) && !defined(CURL_DISABLE_VERBOSE_STRINGS)
  if(sshc->state != nowstate) {
    infof(conn->data, "SFTP %p state change from %s to %s\n",
          sshc, names[sshc->state], names[nowstate]);
  }
#endif

  sshc->state = nowstate;
}

/* figure out the path to work with in this particular request */
static CURLcode ssh_getworkingpath(struct connectdata *conn,
                                   char *homedir,  /* when SFTP is used */
                                   char **path) /* returns the  allocated
                                                   real path to work with */
{
  struct SessionHandle *data = conn->data;
  char *real_path = NULL;
  char *working_path;
  int working_path_len;

  working_path = curl_easy_unescape(data, data->state.path, 0,
                                    &working_path_len);
  if(!working_path)
    return CURLE_OUT_OF_MEMORY;

  /* Check for /~/ , indicating relative to the user's home directory */
  if(conn->protocol & PROT_SCP) {
    real_path = malloc(working_path_len+1);
    if(real_path == NULL) {
      free(working_path);
      return CURLE_OUT_OF_MEMORY;
    }
    if((working_path_len > 1) && (working_path[1] == '~'))
      /* It is referenced to the home directory, so strip the leading '/' */
      memcpy(real_path, working_path+1, 1 + working_path_len-1);
    else
      memcpy(real_path, working_path, 1 + working_path_len);
  }
  else if(conn->protocol & PROT_SFTP) {
    if((working_path_len > 1) && (working_path[1] == '~')) {
      size_t homelen = strlen(homedir);
      real_path = malloc(homelen + working_path_len + 1);
      if(real_path == NULL) {
        free(working_path);
        return CURLE_OUT_OF_MEMORY;
      }
      /* It is referenced to the home directory, so strip the
         leading '/' */
      memcpy(real_path, homedir, homelen);
      real_path[homelen] = '/';
      real_path[homelen+1] = '\0';
      if(working_path_len > 3) {
        memcpy(real_path+homelen+1, working_path + 3,
               1 + working_path_len -3);
      }
    }
    else {
      real_path = malloc(working_path_len+1);
      if(real_path == NULL) {
        free(working_path);
        return CURLE_OUT_OF_MEMORY;
      }
      memcpy(real_path, working_path, 1+working_path_len);
    }
  }

  free(working_path);

  /* store the pointer for the caller to receive */
  *path = real_path;

  return CURLE_OK;
}

#ifdef HAVE_LIBSSH2_KNOWNHOST_API
static int sshkeycallback(CURL *easy,
                          const struct curl_khkey *knownkey, /* known */
                          const struct curl_khkey *foundkey, /* found */
                          enum curl_khmatch match,
                          void *clientp)
{
  (void)easy;
  (void)knownkey;
  (void)foundkey;
  (void)clientp;

  /* we only allow perfect matches, and we reject everything else */
  return (match != CURLKHMATCH_OK)?CURLKHSTAT_REJECT:CURLKHSTAT_FINE;
}
#endif

/*
 * Earlier libssh2 versions didn't have the ability to seek to 64bit positions
 * with 32bit size_t.
 */
#ifdef HAVE_LIBSSH2_SFTP_SEEK64
#define SFTP_SEEK(x,y) libssh2_sftp_seek64(x, (libssh2_uint64_t)y)
#else
#define SFTP_SEEK(x,y) libssh2_sftp_seek(x, (size_t)y)
#endif

/*
 * Earlier libssh2 versions didn't do SCP properly beyond 32bit sizes on 32bit
 * architectures so we check of the necessary function is present.
 */
#ifndef HAVE_LIBSSH2_SCP_SEND64
#define SCP_SEND(a,b,c,d) libssh2_scp_send_ex(a, b, (int)(c), (size_t)d, 0, 0)
#else
#define SCP_SEND(a,b,c,d) libssh2_scp_send64(a, b, (int)(c),            \
                                             (libssh2_uint64_t)d, 0, 0)
#endif

/*
 * libssh2 1.2.8 fixed the problem with 32bit ints used for sockets on win64.
 */
#ifdef HAVE_LIBSSH2_SESSION_HANDSHAKE
#define libssh2_session_startup(x,y) libssh2_session_handshake(x,y)
#endif

/*
 * ssh_statemach_act() runs the SSH state machine as far as it can without
 * blocking and without reaching the end.  The data the pointer 'block' points
 * to will be set to TRUE if the libssh2 function returns LIBSSH2_ERROR_EAGAIN
 * meaning it wants to be called again when the socket is ready
 */

static CURLcode ssh_statemach_act(struct connectdata *conn, bool *block)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  struct SSHPROTO *sftp_scp = data->state.proto.ssh;
  struct ssh_conn *sshc = &conn->proto.sshc;
  curl_socket_t sock = conn->sock[FIRSTSOCKET];
#ifdef CURL_LIBSSH2_DEBUG
  const char *fingerprint;
#endif /* CURL_LIBSSH2_DEBUG */
  const char *host_public_key_md5;
  int rc = LIBSSH2_ERROR_NONE, i;
  int err;
  int seekerr = CURL_SEEKFUNC_OK;
  *block = 0; /* we're not blocking by default */

  do {

    switch(sshc->state) {
    case SSH_S_STARTUP:
      sshc->secondCreateDirs = 0;
      sshc->nextstate = SSH_NO_STATE;
      sshc->actualcode = CURLE_OK;

      rc = libssh2_session_startup(sshc->ssh_session, sock);
      if(rc == LIBSSH2_ERROR_EAGAIN) {
        break;
      }
      else if(rc) {
        failf(data, "Failure establishing ssh session");
        state(conn, SSH_SESSION_FREE);
        sshc->actualcode = CURLE_FAILED_INIT;
        break;
      }

      /* Set libssh2 to non-blocking, since everything internally is
         non-blocking */
      libssh2_session_set_blocking(sshc->ssh_session, 0);

      state(conn, SSH_HOSTKEY);

      /* fall-through */
    case SSH_HOSTKEY:

#ifdef CURL_LIBSSH2_DEBUG
      /*
       * Before we authenticate we should check the hostkey's fingerprint
       * against our known hosts. How that is handled (reading from file,
       * whatever) is up to us. As for know not much is implemented, besides
       * showing how to get the fingerprint.
       */
      fingerprint = libssh2_hostkey_hash(sshc->ssh_session,
                                         LIBSSH2_HOSTKEY_HASH_MD5);

      /* The fingerprint points to static storage (!), don't free() it. */
      infof(data, "Fingerprint: ");
      for (rc = 0; rc < 16; rc++) {
        infof(data, "%02X ", (unsigned char) fingerprint[rc]);
      }
      infof(data, "\n");
#endif /* CURL_LIBSSH2_DEBUG */

      /* Before we authenticate we check the hostkey's MD5 fingerprint
       * against a known fingerprint, if available.  This implementation pulls
       * it from the curl option.
       */
      if(data->set.str[STRING_SSH_HOST_PUBLIC_KEY_MD5] &&
         strlen(data->set.str[STRING_SSH_HOST_PUBLIC_KEY_MD5]) == 32) {
        char buf[33];
        host_public_key_md5 = libssh2_hostkey_hash(sshc->ssh_session,
                                                   LIBSSH2_HOSTKEY_HASH_MD5);
        for (i = 0; i < 16; i++)
          snprintf(&buf[i*2], 3, "%02x",
                   (unsigned char) host_public_key_md5[i]);
        if(!strequal(buf, data->set.str[STRING_SSH_HOST_PUBLIC_KEY_MD5])) {
          failf(data,
                "Denied establishing ssh session: mismatch md5 fingerprint. "
                "Remote %s is not equal to %s",
                buf, data->set.str[STRING_SSH_HOST_PUBLIC_KEY_MD5]);
          state(conn, SSH_SESSION_FREE);
          sshc->actualcode = CURLE_PEER_FAILED_VERIFICATION;
          break;
        }
      }

#ifdef HAVE_LIBSSH2_KNOWNHOST_API
      if(data->set.str[STRING_SSH_KNOWNHOSTS]) {
        /* we're asked to verify the host against a file */
        int keytype;
        size_t keylen;
        const char *remotekey = libssh2_session_hostkey(sshc->ssh_session,
                                                        &keylen, &keytype);
        int keycheck;
        int keybit;

        if(remotekey) {
          /*
           * A subject to figure out is what host name we need to pass in here.
           * What host name does OpenSSH store in its file if an IDN name is
           * used?
           */
          struct libssh2_knownhost *host;
          enum curl_khmatch keymatch;
          curl_sshkeycallback func =
            data->set.ssh_keyfunc?data->set.ssh_keyfunc:sshkeycallback;
          struct curl_khkey knownkey;
          struct curl_khkey *knownkeyp = NULL;
          struct curl_khkey foundkey;

          keybit = (keytype == LIBSSH2_HOSTKEY_TYPE_RSA)?
            LIBSSH2_KNOWNHOST_KEY_SSHRSA:LIBSSH2_KNOWNHOST_KEY_SSHDSS;

          keycheck = libssh2_knownhost_check(sshc->kh,
                                             conn->host.name,
                                             remotekey, keylen,
                                             LIBSSH2_KNOWNHOST_TYPE_PLAIN|
                                             LIBSSH2_KNOWNHOST_KEYENC_RAW|
                                             keybit,
                                             &host);

          infof(data, "SSH host check: %d, key: %s\n", keycheck,
                (keycheck <= LIBSSH2_KNOWNHOST_CHECK_MISMATCH)?
                host->key:"<none>");

          /* setup 'knownkey' */
          if(keycheck <= LIBSSH2_KNOWNHOST_CHECK_MISMATCH) {
            knownkey.key = host->key;
            knownkey.len = 0;
            knownkey.keytype = (keytype == LIBSSH2_HOSTKEY_TYPE_RSA)?
              CURLKHTYPE_RSA : CURLKHTYPE_DSS;
            knownkeyp = &knownkey;
          }

          /* setup 'foundkey' */
          foundkey.key = remotekey;
          foundkey.len = keylen;
          foundkey.keytype = (keytype == LIBSSH2_HOSTKEY_TYPE_RSA)?
            CURLKHTYPE_RSA : CURLKHTYPE_DSS;

          /*
           * if any of the LIBSSH2_KNOWNHOST_CHECK_* defines and the
           * curl_khmatch enum are ever modified, we need to introduce a
           * translation table here!
           */
          keymatch = (enum curl_khmatch)keycheck;

          /* Ask the callback how to behave */
          rc = func(data, knownkeyp, /* from the knownhosts file */
                    &foundkey, /* from the remote host */
                    keymatch, data->set.ssh_keyfunc_userp);
        }
        else
          /* no remotekey means failure! */
          rc = CURLKHSTAT_REJECT;

        switch(rc) {
        default: /* unknown return codes will equal reject */
        case CURLKHSTAT_REJECT:
          state(conn, SSH_SESSION_FREE);
        case CURLKHSTAT_DEFER:
          /* DEFER means bail out but keep the SSH_HOSTKEY state */
          result = sshc->actualcode = CURLE_PEER_FAILED_VERIFICATION;
          break;
        case CURLKHSTAT_FINE:
        case CURLKHSTAT_FINE_ADD_TO_FILE:
          /* proceed */
          if(keycheck != LIBSSH2_KNOWNHOST_CHECK_MATCH) {
            /* the found host+key didn't match but has been told to be fine
               anyway so we add it in memory */
            int addrc = libssh2_knownhost_add(sshc->kh,
                                              conn->host.name, NULL,
                                              remotekey, keylen,
                                              LIBSSH2_KNOWNHOST_TYPE_PLAIN|
                                              LIBSSH2_KNOWNHOST_KEYENC_RAW|
                                              keybit, NULL);
            if(addrc)
              infof(data, "Warning adding the known host %s failed!\n",
                    conn->host.name);
            else if(rc == CURLKHSTAT_FINE_ADD_TO_FILE) {
              /* now we write the entire in-memory list of known hosts to the
                 known_hosts file */
              int wrc =
                libssh2_knownhost_writefile(sshc->kh,
                                            data->set.str[STRING_SSH_KNOWNHOSTS],
                                            LIBSSH2_KNOWNHOST_FILE_OPENSSH);
              if(wrc) {
                infof(data, "Warning, writing %s failed!\n",
                      data->set.str[STRING_SSH_KNOWNHOSTS]);
              }
            }
          }
          break;
        }
      }
#endif /* HAVE_LIBSSH2_KNOWNHOST_API */

      state(conn, SSH_AUTHLIST);
      break;

    case SSH_AUTHLIST:
      /*
       * Figure out authentication methods
       * NB: As soon as we have provided a username to an openssh server we
       * must never change it later. Thus, always specify the correct username
       * here, even though the libssh2 docs kind of indicate that it should be
       * possible to get a 'generic' list (not user-specific) of authentication
       * methods, presumably with a blank username. That won't work in my
       * experience.
       * So always specify it here.
       */
      sshc->authlist = libssh2_userauth_list(sshc->ssh_session,
                                             conn->user,
                                             (unsigned int)strlen(conn->user));

      if(!sshc->authlist) {
        if((err = libssh2_session_last_errno(sshc->ssh_session)) ==
           LIBSSH2_ERROR_EAGAIN) {
          rc = LIBSSH2_ERROR_EAGAIN;
          break;
        }
        else {
          state(conn, SSH_SESSION_FREE);
          sshc->actualcode = libssh2_session_error_to_CURLE(err);
          break;
        }
      }
      infof(data, "SSH authentication methods available: %s\n",
            sshc->authlist);

      state(conn, SSH_AUTH_PKEY_INIT);
      break;

    case SSH_AUTH_PKEY_INIT:
      /*
       * Check the supported auth types in the order I feel is most secure
       * with the requested type of authentication
       */
      sshc->authed = FALSE;

      if((data->set.ssh_auth_types & CURLSSH_AUTH_PUBLICKEY) &&
         (strstr(sshc->authlist, "publickey") != NULL)) {
        char *home;

        sshc->rsa_pub = sshc->rsa = NULL;

        /* To ponder about: should really the lib be messing about with the
           HOME environment variable etc? */
        home = curl_getenv("HOME");

        if(data->set.str[STRING_SSH_PUBLIC_KEY])
          sshc->rsa_pub = aprintf("%s", data->set.str[STRING_SSH_PUBLIC_KEY]);
        else if(home)
          sshc->rsa_pub = aprintf("%s/.ssh/id_dsa.pub", home);
        else
          /* as a final resort, try current dir! */
          sshc->rsa_pub = strdup("id_dsa.pub");

        if(sshc->rsa_pub == NULL) {
          Curl_safefree(home);
          home = NULL;
          state(conn, SSH_SESSION_FREE);
          sshc->actualcode = CURLE_OUT_OF_MEMORY;
          break;
        }

        if(data->set.str[STRING_SSH_PRIVATE_KEY])
          sshc->rsa = aprintf("%s", data->set.str[STRING_SSH_PRIVATE_KEY]);
        else if(home)
          sshc->rsa = aprintf("%s/.ssh/id_dsa", home);
        else
          /* as a final resort, try current dir! */
          sshc->rsa = strdup("id_dsa");

        if(sshc->rsa == NULL) {
          Curl_safefree(home);
          home = NULL;
          Curl_safefree(sshc->rsa_pub);
          sshc->rsa_pub = NULL;
          state(conn, SSH_SESSION_FREE);
          sshc->actualcode = CURLE_OUT_OF_MEMORY;
          break;
        }

        sshc->passphrase = data->set.str[STRING_KEY_PASSWD];
        if(!sshc->passphrase)
          sshc->passphrase = "";

        Curl_safefree(home);
        home = NULL;

        infof(data, "Using ssh public key file %s\n", sshc->rsa_pub);
        infof(data, "Using ssh private key file %s\n", sshc->rsa);

        state(conn, SSH_AUTH_PKEY);
      }
      else {
        state(conn, SSH_AUTH_PASS_INIT);
      }
      break;

    case SSH_AUTH_PKEY:
      /* The function below checks if the files exists, no need to stat() here.
       */
      rc = libssh2_userauth_publickey_fromfile_ex(sshc->ssh_session,
                                                  conn->user,
                                                  (unsigned int)
                                                  strlen(conn->user),
                                                  sshc->rsa_pub,
                                                  sshc->rsa, sshc->passphrase);
      if(rc == LIBSSH2_ERROR_EAGAIN) {
        break;
      }

      Curl_safefree(sshc->rsa_pub);
      sshc->rsa_pub = NULL;
      Curl_safefree(sshc->rsa);
      sshc->rsa = NULL;

      if(rc == 0) {
        sshc->authed = TRUE;
        infof(data, "Initialized SSH public key authentication\n");
        state(conn, SSH_AUTH_DONE);
      }
      else {
        char *err_msg;
        (void)libssh2_session_last_error(sshc->ssh_session,
                                         &err_msg, NULL, 0);
        infof(data, "SSH public key authentication failed: %s\n", err_msg);
        state(conn, SSH_AUTH_PASS_INIT);
      }
      break;

    case SSH_AUTH_PASS_INIT:
      if((data->set.ssh_auth_types & CURLSSH_AUTH_PASSWORD) &&
         (strstr(sshc->authlist, "password") != NULL)) {
        state(conn, SSH_AUTH_PASS);
      }
      else {
        state(conn, SSH_AUTH_HOST_INIT);
      }
      break;

    case SSH_AUTH_PASS:
      rc = libssh2_userauth_password_ex(sshc->ssh_session, conn->user,
                                        (unsigned int)strlen(conn->user),
                                        conn->passwd,
                                        (unsigned int)strlen(conn->passwd),
                                        NULL);
      if(rc == LIBSSH2_ERROR_EAGAIN) {
        break;
      }
      else if(rc == 0) {
        sshc->authed = TRUE;
        infof(data, "Initialized password authentication\n");
        state(conn, SSH_AUTH_DONE);
      }
      else {
        state(conn, SSH_AUTH_HOST_INIT);
      }
      break;

    case SSH_AUTH_HOST_INIT:
      if((data->set.ssh_auth_types & CURLSSH_AUTH_HOST) &&
         (strstr(sshc->authlist, "hostbased") != NULL)) {
        state(conn, SSH_AUTH_HOST);
      }
      else {
        state(conn, SSH_AUTH_KEY_INIT);
      }
      break;

    case SSH_AUTH_HOST:
      state(conn, SSH_AUTH_KEY_INIT);
      break;

    case SSH_AUTH_KEY_INIT:
      if((data->set.ssh_auth_types & CURLSSH_AUTH_KEYBOARD)
         && (strstr(sshc->authlist, "keyboard-interactive") != NULL)) {
        state(conn, SSH_AUTH_KEY);
      }
      else {
        state(conn, SSH_AUTH_DONE);
      }
      break;

    case SSH_AUTH_KEY:
      /* Authentication failed. Continue with keyboard-interactive now. */
      rc = libssh2_userauth_keyboard_interactive_ex(sshc->ssh_session,
                                                    conn->user,
                                                    (unsigned int)
                                                    strlen(conn->user),
                                                    &kbd_callback);
      if(rc == LIBSSH2_ERROR_EAGAIN) {
        break;
      }
      else if(rc == 0) {
        sshc->authed = TRUE;
        infof(data, "Initialized keyboard interactive authentication\n");
      }
      state(conn, SSH_AUTH_DONE);
      break;

    case SSH_AUTH_DONE:
      if(!sshc->authed) {
        failf(data, "Authentication failure");
        state(conn, SSH_SESSION_FREE);
        sshc->actualcode = CURLE_LOGIN_DENIED;
        break;
      }

      /*
       * At this point we have an authenticated ssh session.
       */
      infof(data, "Authentication complete\n");

      Curl_pgrsTime(conn->data, TIMER_APPCONNECT); /* SSH is connected */

      conn->sockfd = sock;
      conn->writesockfd = CURL_SOCKET_BAD;

      if(conn->protocol == PROT_SFTP) {
        state(conn, SSH_SFTP_INIT);
        break;
      }
      infof(data, "SSH CONNECT phase done\n");
      state(conn, SSH_STOP);
      break;

    case SSH_SFTP_INIT:
      /*
       * Start the libssh2 sftp session
       */
      sshc->sftp_session = libssh2_sftp_init(sshc->ssh_session);
      if(!sshc->sftp_session) {
        if(libssh2_session_last_errno(sshc->ssh_session) ==
           LIBSSH2_ERROR_EAGAIN) {
          rc = LIBSSH2_ERROR_EAGAIN;
          break;
        }
        else {
          char *err_msg;

          (void)libssh2_session_last_error(sshc->ssh_session,
                                           &err_msg, NULL, 0);
          failf(data, "Failure initializing sftp session: %s", err_msg);
          state(conn, SSH_SESSION_FREE);
          sshc->actualcode = CURLE_FAILED_INIT;
          break;
        }
      }
      state(conn, SSH_SFTP_REALPATH);
      break;

    case SSH_SFTP_REALPATH:
    {
      char tempHome[PATH_MAX];

      /*
       * Get the "home" directory
       */
      rc = libssh2_sftp_realpath(sshc->sftp_session, ".",
                                 tempHome, PATH_MAX-1);
      if(rc == LIBSSH2_ERROR_EAGAIN) {
        break;
      }
      else if(rc > 0) {
        /* It seems that this string is not always NULL terminated */
        tempHome[rc] = '\0';
        sshc->homedir = strdup(tempHome);
        if(!sshc->homedir) {
          state(conn, SSH_SFTP_CLOSE);
          sshc->actualcode = CURLE_OUT_OF_MEMORY;
          break;
        }
        conn->data->state.most_recent_ftp_entrypath = sshc->homedir;
      }
      else {
        /* Return the error type */
        err = (int)(libssh2_sftp_last_error(sshc->sftp_session));
        result = sftp_libssh2_error_to_CURLE(err);
        sshc->actualcode = result?result:CURLE_SSH;
        DEBUGF(infof(data, "error = %d makes libcurl = %d\n",
                     err, (int)result));
        state(conn, SSH_STOP);
        break;
      }
    }