Added support for libssh SSH SCP back-end

libssh is an alternative library to libssh2.
https://www.libssh.org/

That patch set also introduces support for ECDSA
ed25519 keys, as well as gssapi authentication.

Signed-off-by: Nikos Mavrogiannopoulos <nmav@redhat.com>

1 files changed, 1234 insertions, 0 deletions

diff --git a/lib/ssh-libssh.c b/lib/ssh-libssh.c
new file mode 100644
index 000000000..6c05f6d2d
--- /dev/null
+++ b/lib/ssh-libssh.c
@@ -0,0 +1,1234 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 2017 Red Hat, Inc.
+ *
+ * Authors: Nikos Mavrogiannopoulos, Tomas Mraz, Stanislav Zidek, Robert Kolcun
+ *
+ * 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 https://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.
+ *
+ ***************************************************************************/
+
+#include "curl_setup.h"
+
+#ifdef USE_LIBSSH
+
+#ifdef HAVE_LIMITS_H
+#include <limits.h>
+#endif
+
+#include <libssh/libssh.h>
+
+#ifdef HAVE_FCNTL_H
+#include <fcntl.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
+
+#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 "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 "strdup.h"
+#include "strcase.h"
+#include "vtls/vtls.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"
+
+/* The last 3 #include files should be in this order */
+#include "curl_printf.h"
+#include "curl_memory.h"
+#include "memdebug.h"
+#include "curl_path.h"
+
+/* Local functions: */
+static CURLcode myssh_connect(struct connectdata *conn, bool *done);
+static CURLcode myssh_multi_statemach(struct connectdata *conn,
+                                      bool *done);
+static CURLcode myssh_do_it(struct connectdata *conn, bool *done);
+
+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 int myssh_getsock(struct connectdata *conn, curl_socket_t *sock,
+                         int numsocks);
+
+static int myssh_perform_getsock(const struct connectdata *conn,
+                                 curl_socket_t *sock,
+                                 int numsocks);
+
+static CURLcode myssh_setup_connection(struct connectdata *conn);
+
+/*
+ * SCP protocol handler.
+ */
+
+const struct Curl_handler Curl_handler_scp = {
+  "SCP",                        /* scheme */
+  myssh_setup_connection,       /* setup_connection */
+  myssh_do_it,                  /* do_it */
+  scp_done,                     /* done */
+  ZERO_NULL,                    /* do_more */
+  myssh_connect,                /* connect_it */
+  myssh_multi_statemach,        /* connecting */
+  scp_doing,                    /* doing */
+  myssh_getsock,                /* proto_getsock */
+  myssh_getsock,                /* doing_getsock */
+  ZERO_NULL,                    /* domore_getsock */
+  myssh_perform_getsock,        /* perform_getsock */
+  scp_disconnect,               /* disconnect */
+  ZERO_NULL,                    /* readwrite */
+  ZERO_NULL,                    /* connection_check */
+  PORT_SSH,                     /* defport */
+  CURLPROTO_SCP,                /* protocol */
+  PROTOPT_DIRLOCK | PROTOPT_CLOSEACTION | PROTOPT_NOURLQUERY    /* flags */
+};
+
+/*
+ * SSH State machine related code
+ */
+/* This is the ONLY way to change SSH state! */
+static void state(struct connectdata *conn, sshstate nowstate)
+{
+  struct ssh_conn *sshc = &conn->proto.sshc;
+#if defined(DEBUGBUILD) && !defined(CURL_DISABLE_VERBOSE_STRINGS)
+  /* for debug purposes */
+  static const char *const names[] = {
+    "SSH_STOP",
+    "SSH_INIT",
+    "SSH_S_STARTUP",
+    "SSH_HOSTKEY",
+    "SSH_AUTHLIST",
+    "SSH_AUTH_PKEY_INIT",
+    "SSH_AUTH_PKEY",
+    "SSH_AUTH_PASS_INIT",
+    "SSH_AUTH_PASS",
+    "SSH_AUTH_AGENT_INIT",
+    "SSH_AUTH_AGENT_LIST",
+    "SSH_AUTH_AGENT",
+    "SSH_AUTH_HOST_INIT",
+    "SSH_AUTH_HOST",
+    "SSH_AUTH_KEY_INIT",
+    "SSH_AUTH_KEY",
+    "SSH_AUTH_GSSAPI",
+    "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_QUOTE_STATVFS",
+    "SSH_SFTP_GETINFO",
+    "SSH_SFTP_FILETIME",
+    "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_DOWNLOAD",
+    "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"
+  };
+
+
+  if(sshc->state != nowstate) {
+    infof(conn->data, "SSH %p state change from %s to %s\n",
+          (void *) sshc, names[sshc->state], names[nowstate]);
+  }
+#endif
+
+  sshc->state = nowstate;
+}
+
+/* Multiple options:
+ * 1. data->set.str[STRING_SSH_HOST_PUBLIC_KEY_MD5] is set with an MD5
+ *    hash (90s style auth, not sure we should have it here)
+ * 2. data->set.ssh_keyfunc callback is set. Then we do trust on first
+ *    use. We even save on knownhosts if CURLKHSTAT_FINE_ADD_TO_FILE
+ *    is returned by it.
+ * 3. none of the above. We only accept if it is present on known hosts.
+ *
+ * Returns SSH_OK or SSH_ERROR.
+ */
+static int myssh_is_known(struct connectdata *conn)
+{
+  int rc;
+  struct Curl_easy *data = conn->data;
+  struct ssh_conn *sshc = &conn->proto.sshc;
+  ssh_key pubkey;
+  size_t hlen;
+  unsigned char *hash = NULL;
+  char *base64 = NULL;
+  int vstate;
+  enum curl_khmatch keymatch;
+  struct curl_khkey foundkey;
+  curl_sshkeycallback func =
+    data->set.ssh_keyfunc;
+
+  rc = ssh_get_publickey(sshc->ssh_session, &pubkey);
+  if(rc != SSH_OK)
+    return rc;
+
+  if(data->set.str[STRING_SSH_HOST_PUBLIC_KEY_MD5]) {
+    rc = ssh_get_publickey_hash(pubkey, SSH_PUBLICKEY_HASH_MD5,
+                                &hash, &hlen);
+    if(rc != SSH_OK)
+      goto cleanup;
+
+    if(hlen != strlen(data->set.str[STRING_SSH_HOST_PUBLIC_KEY_MD5]) ||
+       memcmp(&data->set.str[STRING_SSH_HOST_PUBLIC_KEY_MD5], hash, hlen)) {
+          rc = SSH_ERROR;
+          goto cleanup;
+    }
+
+    rc = SSH_OK;
+    goto cleanup;
+  }
+
+  if(data->set.ssl.primary.verifyhost != TRUE) {
+    rc = SSH_OK;
+    goto cleanup;
+  }
+
+  vstate = ssh_is_server_known(sshc->ssh_session);
+  switch(vstate) {
+    case SSH_SERVER_KNOWN_OK:
+      keymatch = CURLKHMATCH_OK;
+    case SSH_SERVER_FILE_NOT_FOUND:
+    case SSH_SERVER_NOT_KNOWN:
+      keymatch = CURLKHMATCH_MISSING;
+    default:
+      keymatch = CURLKHMATCH_MISMATCH;
+  }
+
+  if(func) { /* use callback to determine action */
+    rc = ssh_pki_export_pubkey_base64(pubkey, &base64);
+    if(rc != SSH_OK)
+      goto cleanup;
+
+    foundkey.key = base64;
+    foundkey.len = strlen(base64);
+
+    switch(ssh_key_type(pubkey)) {
+      case SSH_KEYTYPE_RSA:
+        foundkey.keytype = CURLKHTYPE_RSA;
+        break;
+      case SSH_KEYTYPE_RSA1:
+        foundkey.keytype = CURLKHTYPE_RSA1;
+        break;
+      case SSH_KEYTYPE_ECDSA:
+        foundkey.keytype = CURLKHTYPE_ECDSA;
+        break;
+#if LIBSSH_VERSION_INT >= SSH_VERSION_INT(0,7,0)
+      case SSH_KEYTYPE_ED25519:
+        foundkey.keytype = CURLKHTYPE_ED25519;
+        break;
+#endif
+      case SSH_KEYTYPE_DSS:
+        foundkey.keytype = CURLKHTYPE_DSS;
+        break;
+      default:
+        rc = SSH_ERROR;
+        goto cleanup;
+    }
+
+    /* we don't have anything equivalent to knownkey. Always NULL */
+    rc = func(data, NULL, &foundkey, /* from the remote host */
+              keymatch, data->set.ssh_keyfunc_userp);
+
+    switch(rc) {
+      case CURLKHSTAT_FINE_ADD_TO_FILE:
+        rc = ssh_write_knownhost(sshc->ssh_session);
+        if(rc != SSH_OK) {
+          goto cleanup;
+        }
+        break;
+      case CURLKHSTAT_FINE:
+        break;
+      default: /* REJECT/DEFER */
+        rc = SSH_ERROR;
+        goto cleanup;
+    }
+  }
+  else {
+    if(keymatch != CURLKHMATCH_OK) {
+      rc = SSH_ERROR;
+      goto cleanup;
+    }
+  }
+  rc = SSH_OK;
+
+cleanup:
+  if(hash)
+    ssh_clean_pubkey_hash(&hash);
+  ssh_key_free(pubkey);
+  return rc;
+}
+
+#define MOVE_TO_ERROR_STATE(_r) { \
+  state(conn, SSH_SESSION_FREE); \
+  sshc->actualcode = _r; \
+  rc = SSH_ERROR; \
+  break; \
+}
+
+#define MOVE_TO_LAST_AUTH \
+  if(sshc->auth_methods & SSH_AUTH_METHOD_PASSWORD) { \
+    rc = SSH_OK; \
+    state(conn, SSH_AUTH_PASS_INIT); \
+    break; \
+  } \
+  else { \
+    MOVE_TO_ERROR_STATE(CURLE_LOGIN_DENIED); \
+  }
+
+#define MOVE_TO_SECONDARY_AUTH \
+  if(sshc->auth_methods & SSH_AUTH_METHOD_GSSAPI_MIC) { \
+    rc = SSH_OK; \
+    state(conn, SSH_AUTH_GSSAPI); \
+    break; \
+  } \
+  else { \
+    MOVE_TO_LAST_AUTH; \
+  }
+
+
+/*
+ * 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 libssh function returns SSH_AGAIN
+ * meaning it wants to be called again when the socket is ready
+ */
+static CURLcode myssh_statemach_act(struct connectdata *conn, bool *block)
+{
+  CURLcode result = CURLE_OK;
+  struct Curl_easy *data = conn->data;
+  struct SSHPROTO *protop = data->req.protop;
+  struct ssh_conn *sshc = &conn->proto.sshc;
+  int rc = SSH_NO_ERROR;
+  const char *err_msg;
+  *block = 0;                   /* we're not blocking by default */
+
+  do {
+
+    switch(sshc->state) {
+    case SSH_INIT:
+      sshc->secondCreateDirs = 0;
+      sshc->nextstate = SSH_NO_STATE;
+      sshc->actualcode = CURLE_OK;
+
+#if 0
+      ssh_set_log_level(SSH_LOG_PACKET);
+#endif
+
+      /* Set libssh to non-blocking, since everything internally is
+         non-blocking */
+      ssh_set_blocking(sshc->ssh_session, 0);
+
+      state(conn, SSH_S_STARTUP);
+      /* fall-through */
+
+    case SSH_S_STARTUP:
+      rc = ssh_connect(sshc->ssh_session);
+      if(rc == SSH_AGAIN)
+        break;
+
+      if(rc != SSH_OK) {
+        failf(data, "Failure establishing ssh session");
+        MOVE_TO_ERROR_STATE(CURLE_FAILED_INIT);
+      }
+
+      state(conn, SSH_HOSTKEY);
+
+      /* fall-through */
+    case SSH_HOSTKEY:
+
+      rc = myssh_is_known(conn);
+      if(rc != SSH_OK) {
+        MOVE_TO_ERROR_STATE(CURLE_PEER_FAILED_VERIFICATION);
+      }
+
+      state(conn, SSH_AUTHLIST);
+      /* fall through */
+    case SSH_AUTHLIST:{
+        sshc->authed = FALSE;
+
+        rc = ssh_userauth_none(sshc->ssh_session, NULL);
+        if(rc == SSH_AUTH_AGAIN) {
+          rc = SSH_AGAIN;
+          break;
+        }
+
+        if(rc == SSH_AUTH_SUCCESS) {
+          sshc->authed = TRUE;
+          infof(data, "Authenticated with none\n");
+          state(conn, SSH_AUTH_DONE);
+          break;
+        }
+        else if(rc == SSH_AUTH_ERROR) {
+          MOVE_TO_ERROR_STATE(CURLE_LOGIN_DENIED);
+        }
+
+        sshc->auth_methods = ssh_userauth_list(sshc->ssh_session, NULL);
+        if(sshc->auth_methods & SSH_AUTH_METHOD_PUBLICKEY) {
+          state(conn, SSH_AUTH_PKEY_INIT);
+        }
+        else if(sshc->auth_methods & SSH_AUTH_METHOD_GSSAPI_MIC) {
+          state(conn, SSH_AUTH_GSSAPI);
+        }
+        else if(sshc->auth_methods & SSH_AUTH_METHOD_PASSWORD) {
+          state(conn, SSH_AUTH_PASS_INIT);
+        }
+        else {                  /* unsupported authentication method */
+          MOVE_TO_ERROR_STATE(CURLE_LOGIN_DENIED);
+        }
+
+        break;
+      }
+    case SSH_AUTH_PKEY_INIT:
+      if(!(data->set.ssh_auth_types & CURLSSH_AUTH_PUBLICKEY)) {
+        MOVE_TO_SECONDARY_AUTH;
+      }
+
+      /* Two choices, (1) private key was given on CMD,
+       * (2) use the "default" keys. */
+      if(data->set.str[STRING_SSH_PRIVATE_KEY]) {
+        if(sshc->pubkey && !data->set.ssl.key_passwd) {
+          rc = ssh_userauth_try_publickey(sshc->ssh_session, NULL,
+                                          sshc->pubkey);
+          if(rc == SSH_AUTH_AGAIN) {
+            rc = SSH_AGAIN;
+            break;
+          }
+
+          if(rc != SSH_OK) {
+            MOVE_TO_SECONDARY_AUTH;
+          }
+        }
+
+        rc = ssh_pki_import_privkey_file(data->
+                                         set.str[STRING_SSH_PRIVATE_KEY],
+                                         data->set.ssl.key_passwd, NULL,
+                                         NULL, &sshc->privkey);
+        if(rc != SSH_OK) {
+          failf(data, "Could not load private key file %s",
+                data->set.str[STRING_SSH_PRIVATE_KEY]);
+          break;
+        }
+
+        state(conn, SSH_AUTH_PKEY);
+        break;
+
+      }
+      else {
+        infof(data, "Authentication using SSH public key file\n");
+
+        rc = ssh_userauth_publickey_auto(sshc->ssh_session, NULL,
+                                         data->set.ssl.key_passwd);
+        if(rc == SSH_AUTH_AGAIN) {
+          rc = SSH_AGAIN;
+          break;
+        }
+        if(rc == SSH_AUTH_SUCCESS) {
+          rc = SSH_OK;
+          sshc->authed = TRUE;
+          infof(data, "Completed public key authentication\n");
+          state(conn, SSH_AUTH_DONE);
+          break;
+        }
+
+        MOVE_TO_SECONDARY_AUTH;
+      }
+      break;
+    case SSH_AUTH_PKEY:
+      rc = ssh_userauth_publickey(sshc->ssh_session, NULL, sshc->privkey);
+      if(rc == SSH_AUTH_AGAIN) {
+        rc = SSH_AGAIN;
+        break;
+      }
+
+      if(rc == SSH_AUTH_SUCCESS) {
+        sshc->authed = TRUE;
+        infof(data, "Completed public key authentication\n");
+        state(conn, SSH_AUTH_DONE);
+        break;
+      }
+      else {
+        infof(data, "Failed public key authentication (rc: %d)\n", rc);
+        MOVE_TO_SECONDARY_AUTH;
+      }
+      break;
+
+    case SSH_AUTH_GSSAPI:
+      if(!(data->set.ssh_auth_types & CURLSSH_AUTH_GSSAPI)) {
+        MOVE_TO_LAST_AUTH;
+      }
+
+      rc = ssh_userauth_gssapi(sshc->ssh_session);
+      if(rc == SSH_AUTH_AGAIN) {
+        rc = SSH_AGAIN;
+        break;
+      }
+
+      if(rc == SSH_AUTH_SUCCESS) {
+        rc = SSH_OK;
+        sshc->authed = TRUE;
+        infof(data, "Completed gssapi authentication\n");
+        state(conn, SSH_AUTH_DONE);
+        break;
+      }
+
+      MOVE_TO_LAST_AUTH;
+      break;
+
+    case SSH_AUTH_PASS_INIT:
+      if(!(data->set.ssh_auth_types & CURLSSH_AUTH_PASSWORD)) {
+        /* Host key authentication is intentionally not implemented */
+        MOVE_TO_ERROR_STATE(CURLE_LOGIN_DENIED);
+      }
+      state(conn, SSH_AUTH_PASS);
+      /* fall through */
+
+    case SSH_AUTH_PASS:
+      rc = ssh_userauth_password(sshc->ssh_session, NULL, conn->passwd);
+      if(rc == SSH_AUTH_AGAIN) {
+        rc = SSH_AGAIN;
+        break;
+      }
+
+      if(rc == SSH_AUTH_SUCCESS) {
+        sshc->authed = TRUE;
+        infof(data, "Completed password authentication\n");
+        state(conn, SSH_AUTH_DONE);
+      }
+      else {
+        MOVE_TO_ERROR_STATE(CURLE_LOGIN_DENIED);
+      }
+      break;
+
+    case SSH_AUTH_DONE:
+      if(!sshc->authed) {
+        failf(data, "Authentication failure");
+        MOVE_TO_ERROR_STATE(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 = ssh_get_fd(sshc->ssh_session);
+      conn->writesockfd = CURL_SOCKET_BAD;
+
+      infof(data, "SSH CONNECT phase done\n");
+      state(conn, SSH_STOP);
+      break;
+
+    case SSH_SCP_TRANS_INIT:
+      result = Curl_getworkingpath(conn, sshc->homedir, &protop->path);
+      if(result) {
+        sshc->actualcode = result;
+        state(conn, SSH_STOP);
+        break;
+      }
+
+      /* Functions from the SCP subsystem cannot handle/return SSH_AGAIN */
+      ssh_set_blocking(sshc->ssh_session, 1);
+
+      if(data->set.upload) {
+        if(data->state.infilesize < 0) {
+          failf(data, "SCP requires a known file size for upload");
+          sshc->actualcode = CURLE_UPLOAD_FAILED;
+          MOVE_TO_ERROR_STATE(CURLE_UPLOAD_FAILED);
+        }
+
+        sshc->scp_session =
+          ssh_scp_new(sshc->ssh_session, SSH_SCP_WRITE, protop->path);
+        state(conn, SSH_SCP_UPLOAD_INIT);
+      }
+      else {
+        sshc->scp_session =
+          ssh_scp_new(sshc->ssh_session, SSH_SCP_READ, protop->path);
+        state(conn, SSH_SCP_DOWNLOAD_INIT);
+      }
+
+      if(!sshc->scp_session) {
+        err_msg = ssh_get_error(sshc->ssh_session);
+        failf(conn->data, "%s", err_msg);
+        MOVE_TO_ERROR_STATE(CURLE_UPLOAD_FAILED);
+      }
+
+      break;
+
+    case SSH_SCP_UPLOAD_INIT:
+
+      rc = ssh_scp_init(sshc->scp_session);
+      if(rc != SSH_OK) {
+        err_msg = ssh_get_error(sshc->ssh_session);
+        failf(conn->data, "%s", err_msg);
+        MOVE_TO_ERROR_STATE(CURLE_UPLOAD_FAILED);
+      }
+
+      rc = ssh_scp_push_file(sshc->scp_session, protop->path,
+                             data->state.infilesize,
+                             (int)data->set.new_file_perms);
+      if(rc != SSH_OK) {
+        err_msg = ssh_get_error(sshc->ssh_session);
+        failf(conn->data, "%s", err_msg);
+        MOVE_TO_ERROR_STATE(CURLE_UPLOAD_FAILED);
+      }
+
+      /* upload data */
+      Curl_setup_transfer(conn, -1, data->req.size, FALSE, NULL,
+                          FIRSTSOCKET, NULL);
+
+      /* not set by Curl_setup_transfer to preserve keepon bits */
+      conn->sockfd = conn->writesockfd;
+
+      /* store this original bitmask setup to use later on if we can't
+         figure out a "real" bitmask */
+      sshc->orig_waitfor = data->req.keepon;
+
+      /* we want to use the _sending_ function even when the socket turns
+         out readable as the underlying libssh scp send function will deal
+         with both accordingly */
+      conn->cselect_bits = CURL_CSELECT_OUT;
+
+      state(conn, SSH_STOP);
+
+      break;
+
+    case SSH_SCP_DOWNLOAD_INIT:
+
+      rc = ssh_scp_init(sshc->scp_session);
+      if(rc != SSH_OK) {
+        err_msg = ssh_get_error(sshc->ssh_session);
+        failf(conn->data, "%s", err_msg);
+        MOVE_TO_ERROR_STATE(CURLE_COULDNT_CONNECT);
+      }
+      state(conn, SSH_SCP_DOWNLOAD);
+      /* fall through */
+
+    case SSH_SCP_DOWNLOAD:{
+        curl_off_t bytecount;
+
+        rc = ssh_scp_pull_request(sshc->scp_session);
+        if(rc != SSH_SCP_REQUEST_NEWFILE) {
+          err_msg = ssh_get_error(sshc->ssh_session);
+          failf(conn->data, "%s", err_msg);
+          MOVE_TO_ERROR_STATE(CURLE_REMOTE_FILE_NOT_FOUND);
+          break;
+        }
+
+        /* download data */
+        bytecount = ssh_scp_request_get_size(sshc->scp_session);
+        data->req.maxdownload = (curl_off_t) bytecount;
+        Curl_setup_transfer(conn, FIRSTSOCKET, bytecount, FALSE, NULL, -1,
+                            NULL);
+
+        /* not set by Curl_setup_transfer to preserve keepon bits */
+        conn->writesockfd = conn->sockfd;
+
+        /* we want to use the _receiving_ function even when the socket turns
+           out writableable as the underlying libssh recv function will deal
+           with both accordingly */
+        conn->cselect_bits = CURL_CSELECT_IN;
+
+        state(conn, SSH_STOP);
+        break;
+      }
+    case SSH_SCP_DONE:
+      if(data->set.upload)
+        state(conn, SSH_SCP_SEND_EOF);
+      else
+        state(conn, SSH_SCP_CHANNEL_FREE);
+      break;
+
+    case SSH_SCP_SEND_EOF:
+      if(sshc->scp_session) {
+        rc = ssh_scp_close(sshc->scp_session);
+        if(rc == SSH_AGAIN) {
+          /* Currently the ssh_scp_close handles waiting for EOF in
+           * blocking way.
+           */
+          break;
+        }
+        if(rc != SSH_OK) {
+          infof(data, "Failed to close libssh scp channel: %s\n",
+                ssh_get_error(sshc->ssh_session));
+        }
+      }
+
+      state(conn, SSH_SCP_CHANNEL_FREE);
+      break;
+
+    case SSH_SCP_CHANNEL_FREE:
+      if(sshc->scp_session) {
+        ssh_scp_free(sshc->scp_session);
+        sshc->scp_session = NULL;
+      }
+      DEBUGF(infof(data, "SCP DONE phase complete\n"));
+
+      ssh_set_blocking(sshc->ssh_session, 0);
+
+      state(conn, SSH_SESSION_DISCONNECT);
+      /* fall through */
+
+    case SSH_SESSION_DISCONNECT:
+      /* during weird times when we've been prematurely aborted, the channel
+         is still alive when we reach this state and we MUST kill the channel
+         properly first */
+      if(sshc->scp_session) {
+        ssh_scp_free(sshc->scp_session);
+        sshc->scp_session = NULL;
+      }
+
+      ssh_disconnect(sshc->ssh_session);
+
+      Curl_safefree(sshc->homedir);
+      conn->data->state.most_recent_ftp_entrypath = NULL;
+
+      state(conn, SSH_SESSION_FREE);
+      /* fall through */
+    case SSH_SESSION_FREE:
+      if(sshc->ssh_session) {
+        ssh_free(sshc->ssh_session);
+        sshc->ssh_session = NULL;
+      }
+
+      /* worst-case scenario cleanup */
+
+      DEBUGASSERT(sshc->ssh_session == NULL);
+      DEBUGASSERT(sshc->scp_session == NULL);
+
+      if(sshc->privkey)
+        ssh_key_free(sshc->privkey);
+      if(sshc->pubkey)
+        ssh_key_free(sshc->pubkey);
+
+      Curl_safefree(sshc->rsa_pub);
+      Curl_safefree(sshc->rsa);
+
+      Curl_safefree(sshc->quote_path1);
+      Curl_safefree(sshc->quote_path2);
+
+      Curl_safefree(sshc->homedir);
+
+      Curl_safefree(sshc->readdir_filename);
+      Curl_safefree(sshc->readdir_longentry);
+      Curl_safefree(sshc->readdir_line);
+      Curl_safefree(sshc->readdir_linkPath);
+
+      /* the code we are about to return */
+      result = sshc->actualcode;
+
+      memset(sshc, 0, sizeof(struct ssh_conn));
+
+      connclose(conn, "SSH session free");
+      sshc->state = SSH_SESSION_FREE;   /* current */
+      sshc->nextstate = SSH_NO_STATE;
+      state(conn, SSH_STOP);
+      break;
+
+    case SSH_QUIT:
+      /* fallthrough, just stop! */
+    default:
+      /* internal error */
+      sshc->nextstate = SSH_NO_STATE;
+      state(conn, SSH_STOP);
+      break;
+
+    }
+  } while(!rc && (sshc->state != SSH_STOP));
+
+
+  if(rc == SSH_AGAIN) {
+    /* we would block, we need to wait for the socket to be ready (in the
+       right direction too)! */
+    *block = TRUE;
+  }
+
+  return result;
+}
+
+
+/* called by the multi interface to figure out what socket(s) to wait for and
+   for what actions in the DO_DONE, PERFORM and WAITPERFORM states */
+static int myssh_perform_getsock(const struct connectdata *conn,
+                                 curl_socket_t *sock,  /* points to numsocks
+                                                          number of sockets */
+                                 int numsocks)
+{
+  int bitmap = GETSOCK_BLANK;
+  (void) numsocks;
+
+  sock[0] = conn->sock[FIRSTSOCKET];
+
+  if(conn->waitfor & KEEP_RECV)
+    bitmap |= GETSOCK_READSOCK(FIRSTSOCKET);
+
+  if(conn->waitfor & KEEP_SEND)
+    bitmap |= GETSOCK_WRITESOCK(FIRSTSOCKET);
+
+  return bitmap;
+}
+
+/* Generic function called by the multi interface to figure out what socket(s)
+   to wait for and for what actions during the DOING and PROTOCONNECT states*/
+static int myssh_getsock(struct connectdata *conn,
+                         curl_socket_t *sock,  /* points to numsocks
+                                                   number of sockets */
+                         int numsocks)
+{
+  /* if we know the direction we can use the generic *_getsock() function even
+     for the protocol_connect and doing states */
+  return myssh_perform_getsock(conn, sock, numsocks);
+}
+
+static void myssh_block2waitfor(struct connectdata *conn, bool block)
+{
+  struct ssh_conn *sshc = &conn->proto.sshc;
+  int dir;
+
+  /* If it didn't block, or nothing was returned by ssh_get_poll_flags
+   * have the original set */
+  conn->waitfor = sshc->orig_waitfor;
+
+  if(block) {
+    dir = ssh_get_poll_flags(sshc->ssh_session);
+    if(dir & SSH_READ_PENDING) {
+      /* translate the libssh2 define bits into our own bit defines */
+      conn->waitfor = KEEP_RECV;
+    }
+    else if(dir & SSH_WRITE_PENDING) {
+      conn->waitfor = KEEP_SEND;
+    }
+  }
+}
+
+/* called repeatedly until done from multi.c */
+static CURLcode myssh_multi_statemach(struct connectdata *conn,
+                                      bool *done)
+{
+  struct ssh_conn *sshc = &conn->proto.sshc;
+  CURLcode result = CURLE_OK;
+  bool block;    /* we store the status and use that to provide a ssh_getsock()
+                    implementation */
+
+  result = myssh_statemach_act(conn, &block);
+  *done = (sshc->state == SSH_STOP) ? TRUE : FALSE;
+  myssh_block2waitfor(conn, block);
+
+  return result;
+}
+
+static CURLcode myssh_block_statemach(struct connectdata *conn,
+                                      bool disconnect)
+{
+  struct ssh_conn *sshc = &conn->proto.sshc;
+  CURLcode result = CURLE_OK;
+  struct Curl_easy *data = conn->data;
+
+  while((sshc->state != SSH_STOP) && !result) {
+    bool block;
+    timediff_t left = 1000;
+    struct curltime now = Curl_now();
+
+    result = myssh_statemach_act(conn, &block);
+    if(result)
+      break;
+
+    if(!disconnect) {
+      if(Curl_pgrsUpdate(conn))
+        return CURLE_ABORTED_BY_CALLBACK;
+
+      result = Curl_speedcheck(data, now);
+      if(result)
+        break;
+
+      left = Curl_timeleft(data, NULL, FALSE);
+      if(left < 0) {
+        failf(data, "Operation timed out");
+        return CURLE_OPERATION_TIMEDOUT;
+      }
+    }
+
+    if(!result && block) {
+      curl_socket_t sock = conn->sock[FIRSTSOCKET];
+      curl_socket_t fd_read = CURL_SOCKET_BAD;
+      fd_read = sock;
+      /* wait for the socket to become ready */
+      (void) Curl_socket_check(fd_read, CURL_SOCKET_BAD,
+                               CURL_SOCKET_BAD, left > 1000 ? 1000 : left);
+    }
+
+  }
+
+  return result;
+}
+
+/*
+ * SSH setup connection
+ */
+static CURLcode myssh_setup_connection(struct connectdata *conn)
+{
+  struct SSHPROTO *ssh;
+
+  conn->data->req.protop = ssh = calloc(1, sizeof(struct SSHPROTO));
+  if(!ssh)
+    return CURLE_OUT_OF_MEMORY;
+
+  return CURLE_OK;
+}
+
+static Curl_recv scp_recv;
+static Curl_send scp_send;
+
+/*
+ * Curl_ssh_connect() gets called from Curl_protocol_connect() to allow us to
+ * do protocol-specific actions at connect-time.
+ */
+static CURLcode myssh_connect(struct connectdata *conn, bool *done)
+{
+  struct ssh_conn *ssh;
+  CURLcode result;
+  struct Curl_easy *data = conn->data;
+  int rc;
+
+  /* initialize per-handle data if not already */
+  if(!data->req.protop)
+    myssh_setup_connection(conn);
+
+  /* We default to persistent connections. We set this already in this connect
+     function to make the re-use checks properly be able to check this bit. */
+  connkeep(conn, "SSH default");
+
+  if(conn->handler->protocol & CURLPROTO_SCP) {
+    conn->recv[FIRSTSOCKET] = scp_recv;
+    conn->send[FIRSTSOCKET] = scp_send;
+  }
+  else
+    return CURLE_SSH;
+
+  ssh = &conn->proto.sshc;
+
+  ssh->ssh_session = ssh_new();
+  if(ssh->ssh_session == NULL) {
+    failf(data, "Failure initialising ssh session");
+    return CURLE_FAILED_INIT;
+  }
+
+  if(conn->user) {
+    infof(data, "User: %s\n", conn->user);
+    ssh_options_set(ssh->ssh_session, SSH_OPTIONS_USER, conn->user);
+  }
+
+  if(data->set.str[STRING_SSH_KNOWNHOSTS]) {
+    infof(data, "Known hosts: %s\n", data->set.str[STRING_SSH_KNOWNHOSTS]);
+    ssh_options_set(ssh->ssh_session, SSH_OPTIONS_KNOWNHOSTS,
+                    data->set.str[STRING_SSH_KNOWNHOSTS]);
+  }
+
+  ssh_options_set(ssh->ssh_session, SSH_OPTIONS_HOST, conn->host.name);
+  if(conn->remote_port)
+    ssh_options_set(ssh->ssh_session, SSH_OPTIONS_PORT,
+                    &conn->remote_port);
+
+  if(data->set.ssh_compression) {
+    ssh_options_set(ssh->ssh_session, SSH_OPTIONS_COMPRESSION,
+                    "zlib,zlib@openssh.com,none");
+  }
+
+  ssh->privkey = NULL;
+  ssh->pubkey = NULL;
+
+  if(data->set.str[STRING_SSH_PUBLIC_KEY]) {
+    rc = ssh_pki_import_pubkey_file(data->set.str[STRING_SSH_PUBLIC_KEY],
+                                    &ssh->pubkey);
+    if(rc != SSH_OK) {
+      failf(data, "Could not load public key file");
+      /* ignore */
+    }
+  }
+
+  /* we do not verify here, we do it at the state machine,
+   * after connection */
+
+  state(conn, SSH_INIT);
+
+  result = myssh_multi_statemach(conn, done);
+
+  return result;
+}
+
+/* called from multi.c while DOing */
+static CURLcode scp_doing(struct connectdata *conn, bool *dophase_done)
+{
+  CURLcode result;
+
+  result = myssh_multi_statemach(conn, dophase_done);
+
+  if(*dophase_done) {
+    DEBUGF(infof(conn->data, "DO phase is complete\n"));
+  }
+  return result;
+}
+
+/*
+ ***********************************************************************
+ *
+ * scp_perform()
+ *
+ * This is the actual DO function for SCP. Get a file according to
+ * the options previously setup.
+ */
+
+static
+CURLcode scp_perform(struct connectdata *conn,
+                     bool *connected, bool *dophase_done)
+{
+  CURLcode result = CURLE_OK;
+
+  DEBUGF(infof(conn->data, "DO phase starts\n"));
+
+  *dophase_done = FALSE;        /* not done yet */
+
+  /* start the first command in the DO phase */
+  state(conn, SSH_SCP_TRANS_INIT);
+
+  result = myssh_multi_statemach(conn, dophase_done);
+
+  *connected = conn->bits.tcpconnect[FIRSTSOCKET];
+
+  if(*dophase_done) {
+    DEBUGF(infof(conn->data, "DO phase is complete\n"));
+  }
+
+  return result;
+}
+
+static CURLcode myssh_do_it(struct connectdata *conn, bool *done)
+{
+  CURLcode result;
+  bool connected = 0;
+  struct Curl_easy *data = conn->data;
+  struct ssh_conn *sshc = &conn->proto.sshc;
+
+  *done = FALSE;                /* default to false */
+
+  data->req.size = -1;          /* make sure this is unknown at this point */
+
+  sshc->actualcode = CURLE_OK;  /* reset error code */
+  sshc->secondCreateDirs = 0;   /* reset the create dir attempt state
+                                   variable */
+
+  Curl_pgrsSetUploadCounter(data, 0);
+  Curl_pgrsSetDownloadCounter(data, 0);
+  Curl_pgrsSetUploadSize(data, -1);
+  Curl_pgrsSetDownloadSize(data, -1);
+
+  if(conn->handler->protocol & CURLPROTO_SCP)
+    result = scp_perform(conn, &connected, done);
+  else
+    result = CURLE_SSH;
+
+  return result;
+}
+
+/* BLOCKING, but the function is using the state machine so the only reason
+   this is still blocking is that the multi interface code has no support for
+   disconnecting operations that takes a while */
+static CURLcode scp_disconnect(struct connectdata *conn,
+                               bool dead_connection)
+{
+  CURLcode result = CURLE_OK;
+  struct ssh_conn *ssh = &conn->proto.sshc;
+  (void) dead_connection;
+
+  if(ssh->ssh_session) {
+    /* only if there's a session still around to use! */
+
+    state(conn, SSH_SESSION_DISCONNECT);
+
+    result = myssh_block_statemach(conn, TRUE);
+  }
+
+  return result;
+}
+
+/* generic done function for both SCP and SFTP called from their specific
+   done functions */
+static CURLcode myssh_done(struct connectdata *conn, CURLcode status)
+{
+  CURLcode result = CURLE_OK;
+  struct SSHPROTO *protop = conn->data->req.protop;
+
+  if(!status) {
+    /* run the state-machine
+
+       TODO: when the multi interface is used, this _really_ should be using
+       the ssh_multi_statemach function but we have no general support for
+       non-blocking DONE operations!
+     */
+    result = myssh_block_statemach(conn, FALSE);
+  }
+  else
+    result = status;
+
+  if(protop)
+    Curl_safefree(protop->path);
+  if(Curl_pgrsDone(conn))
+    return CURLE_ABORTED_BY_CALLBACK;
+
+  conn->data->req.keepon = 0;   /* clear all bits */
+  return result;
+}
+
+
+static CURLcode scp_done(struct connectdata *conn, CURLcode status,
+                         bool premature)
+{
+  (void) premature;             /* not used */
+
+  if(!status)
+    state(conn, SSH_SCP_DONE);
+
+  return myssh_done(conn, status);
+
+}
+
+static ssize_t scp_send(struct connectdata *conn, int sockindex,
+                        const void *mem, size_t len, CURLcode *err)
+{
+  int rc;
+  (void) sockindex; /* we only support SCP on the fixed known primary socket */
+  (void) err;
+
+  rc = ssh_scp_write(conn->proto.sshc.scp_session, mem, len);
+
+#if 0
+  /* The following code is misleading, mostly added as wishful thinking
+   * that libssh at some point will implement non-blocking ssh_scp_write/read.
+   * Currently rc can only be number of bytes read or SSH_ERROR. */
+  myssh_block2waitfor(conn, (rc == SSH_AGAIN) ? TRUE : FALSE);
+
+  if(rc == SSH_AGAIN) {
+    *err = CURLE_AGAIN;
+    return 0;
+  }
+  else
+#endif
+  if(rc != SSH_OK) {
+    *err = CURLE_SSH;
+    return -1;
+  }
+
+  return len;
+}
+
+static ssize_t scp_recv(struct connectdata *conn, int sockindex,
+                        char *mem, size_t len, CURLcode *err)
+{
+  ssize_t nread;
+  (void) err;
+  (void) sockindex; /* we only support SCP on the fixed known primary socket */
+
+  /* libssh returns int */
+  nread = ssh_scp_read(conn->proto.sshc.scp_session, mem, len);
+
+#if 0
+  /* The following code is misleading, mostly added as wishful thinking
+   * that libssh at some point will implement non-blocking ssh_scp_write/read.
+   * Currently rc can only be SSH_OK or SSH_ERROR. */
+
+  myssh_block2waitfor(conn, (nread == SSH_AGAIN) ? TRUE : FALSE);
+  if(nread == SSH_AGAIN) {
+    *err = CURLE_AGAIN;
+    nread = -1;
+  }
+#endif
+
+  return nread;
+}
+
+#endif                          /* USE_LIBSSH */