[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]

[libvirt] [PATCH 2/5] libssh2_transport: add main libssh2 transport implementation



This patch adds helper functions to libssh2 that enable us to use
libssh2 in conjunction with libvirt-native virNetSockets instead of
using a spawned "ssh" client process.

This implemetation supports tunneled plaintext, keyboard-interactive,
private key, ssh agent based and null authentication. Libvirt's Auth
callback is used for interaction with the user. (Keyboard interactive
authentication, adding of host keys, private key passphrases). This
enables seamless integration into the application using libvirt, as no
helpers as "ssh-askpass" are needed.

Reading and writing of OpenSSH style "known_hosts" files is supported.

Communication is done using SSH exec channel, where the user may specify
arbitrary command to be executed on the remote side and reads and writes
to/from stdin/out are sent through the ssh channel. Usage of stderr is
not supported.

As a bonus, this should (untested) add SSH support to libvirt clients
running on Windows.
---
 configure.ac                  |   40 +-
 include/libvirt/virterror.h   |    2 +
 po/POTFILES.in                |    1 +
 src/Makefile.am               |    9 +
 src/rpc/virnetlibsshcontext.c | 1444 +++++++++++++++++++++++++++++++++++++++++
 src/rpc/virnetlibsshcontext.h |   83 +++
 src/util/virterror.c          |    8 +-
 7 files changed, 1582 insertions(+), 5 deletions(-)
 create mode 100644 src/rpc/virnetlibsshcontext.c
 create mode 100644 src/rpc/virnetlibsshcontext.h

diff --git a/configure.ac b/configure.ac
index 8a04d91..1810979 100644
--- a/configure.ac
+++ b/configure.ac
@@ -73,6 +73,7 @@ OPENWSMAN_REQUIRED="2.2.3"
 LIBPCAP_REQUIRED="1.0.0"
 LIBNL_REQUIRED="1.1"
 LIBSSH2_REQUIRED="1.0"
+LIBSSH2_TRANSPORT_REQUIRED="1.3"
 LIBBLKID_REQUIRED="2.17"
 DBUS_REQUIRED="1.0.0"

@@ -401,6 +402,8 @@ AC_ARG_WITH([console-lock-files],
                   (use auto for default paths on some platforms)
                   @<:@default=auto@:>@]),
   [],[with_console_lock_files=auto])
+AC_ARG_WITH([libssh2_transport],
+  AC_HELP_STRING([--with-libssh2_transport], [libssh2 location @<:@default=check@:>@]),[],[with_libssh2_transport=check])

 dnl
 dnl in case someone want to build static binaries
@@ -1706,29 +1709,58 @@ AM_CONDITIONAL([WITH_UML], [test "$with_uml" = "yes"])


 dnl
-dnl check for libssh2 (PHYP)
+dnl check for libssh2 (PHYP and libssh2 transport)
 dnl

 LIBSSH2_CFLAGS=""
 LIBSSH2_LIBS=""

-if test "$with_phyp" = "yes" || test "$with_phyp" = "check"; then
+if test "$with_phyp" = "yes" || test "$with_phyp" = "check" ||
+   test "$with_libssh2_transport" = "yes"  || test "$with_libssh2_transport" = "check"; then
     PKG_CHECK_MODULES([LIBSSH2], [libssh2 >= $LIBSSH2_REQUIRED], [
-        with_phyp=yes
+        if test "$with_phyp" = "check"; then
+            with_phyp=yes
+        fi
+        if $PKG_CONFIG "libssh2 >= $LIBSSH2_TRANSPORT_REQUIRED"; then
+            if test "$with_libssh2_transport" = "check"; then
+                with_libssh2_transport=yes
+            fi
+        else
+            if test "$with_libssh2_transport" = "check"; then
+                with_libssh2_transport=no
+                AC_MSG_NOTICE([libssh2 >= $LIBSSH2_TRANSPORT_REQUIRED is required for libssh2 transport])
+            fi
+            if test "$with_libssh2_transport" = "yes"; then
+                AC_MSG_ERROR([libssh2 >= $LIBSSH2_TRANSPORT_REQUIRED is required for libssh2 transport])
+            fi
+        fi
     ], [
         if test "$with_phyp" = "check"; then
             with_phyp=no
             AC_MSG_NOTICE([libssh2 is required for Phyp driver, disabling it])
-        else
+        fi
+        if test "$with_phyp" = "yes"; then
             AC_MSG_ERROR([libssh2 >= $LIBSSH2_REQUIRED is required for Phyp driver])
         fi
+        if test "$with_libssh2_transport" = "check"; then
+            with_libssh2_transport=no
+            AC_MSG_NOTICE([libssh2 >= $LIBSSH2_TRANSPORT_REQUIRED is required for libssh2 transport])
+        fi
+        if test "$with_libssh2_transport" = "yes"; then
+            AC_MSG_ERROR([libssh2 >= $LIBSSH2_TRANSPORT_REQUIRED is required for libssh2 transport])
+        fi
     ])
 fi

 if test "$with_phyp" = "yes"; then
     AC_DEFINE_UNQUOTED([WITH_PHYP], 1, [whether IBM HMC / IVM driver is enabled])
 fi
+if test "$with_libssh2_transport" = "yes"; then
+    AC_DEFINE_UNQUOTED([HAVE_LIBSSH2], 1, [wether libssh2 transport is enabled])
+fi
+
 AM_CONDITIONAL([WITH_PHYP],[test "$with_phyp" = "yes"])
+AM_CONDITIONAL([HAVE_LIBSSH2], [test "$with_libssh2_transport" = "yes"])

 AC_SUBST([LIBSSH2_CFLAGS])
 AC_SUBST([LIBSSH2_LIBS])
diff --git a/include/libvirt/virterror.h b/include/libvirt/virterror.h
index ad8e101..13a2b9d 100644
--- a/include/libvirt/virterror.h
+++ b/include/libvirt/virterror.h
@@ -110,6 +110,7 @@ typedef enum {
     VIR_FROM_AUTH = 46,         /* Error from auth handling */
     VIR_FROM_DBUS = 47,         /* Error from DBus */
     VIR_FROM_PARALLELS = 48,    /* Error from Parallels */
+    VIR_FROM_LIBSSH = 49,       /* Error from libssh2 connection transport */

 # ifdef VIR_ENUM_SENTINELS
     VIR_ERR_DOMAIN_LAST
@@ -277,6 +278,7 @@ typedef enum {
     VIR_ERR_MIGRATE_UNSAFE = 81,        /* Migration is not safe */
     VIR_ERR_OVERFLOW = 82,              /* integer overflow */
     VIR_ERR_BLOCK_COPY_ACTIVE = 83,     /* action prevented by block copy job */
+    VIR_ERR_LIBSSH_ERROR = 84,          /* error in libssh2 transport driver */
 } virErrorNumber;

 /**
diff --git a/po/POTFILES.in b/po/POTFILES.in
index 37a00ee..83eab5e 100644
--- a/po/POTFILES.in
+++ b/po/POTFILES.in
@@ -90,6 +90,7 @@ src/rpc/virkeepalive.c
 src/rpc/virnetclient.c
 src/rpc/virnetclientprogram.c
 src/rpc/virnetclientstream.c
+src/rpc/virnetlibsshcontext.c
 src/rpc/virnetmessage.c
 src/rpc/virnetsaslcontext.c
 src/rpc/virnetsocket.c
diff --git a/src/Makefile.am b/src/Makefile.am
index d4c198e..b49761a 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1508,6 +1508,13 @@ libvirt_net_rpc_la_SOURCES = \
 	rpc/virnettlscontext.h rpc/virnettlscontext.c \
 	rpc/virkeepaliveprotocol.h rpc/virkeepaliveprotocol.c \
 	rpc/virkeepalive.h rpc/virkeepalive.c
+if HAVE_LIBSSH2
+libvirt_net_rpc_la_SOURCES += \
+	rpc/virnetlibsshcontext.h rpc/virnetlibsshcontext.c
+else
+EXTRA_DIST += \
+	rpc/virnetlibsshcontext.h rpc/virnetlibsshcontext.c
+endif
 if HAVE_SASL
 libvirt_net_rpc_la_SOURCES += \
 	rpc/virnetsaslcontext.h rpc/virnetsaslcontext.c
@@ -1518,11 +1525,13 @@ endif
 libvirt_net_rpc_la_CFLAGS = \
 			$(GNUTLS_CFLAGS) \
 			$(SASL_CFLAGS) \
+			$(LIBSSH2_CFLAGS) \
 			$(XDR_CFLAGS) \
 			$(AM_CFLAGS)
 libvirt_net_rpc_la_LDFLAGS = \
 			$(GNUTLS_LIBS) \
 			$(SASL_LIBS) \
+			$(LIBSSH2_LIBS)\
 			$(AM_LDFLAGS) \
 			$(CYGWIN_EXTRA_LDFLAGS) \
 			$(MINGW_EXTRA_LDFLAGS)
diff --git a/src/rpc/virnetlibsshcontext.c b/src/rpc/virnetlibsshcontext.c
new file mode 100644
index 0000000..fa61226
--- /dev/null
+++ b/src/rpc/virnetlibsshcontext.c
@@ -0,0 +1,1444 @@
+/*
+ * virnetlibsshcontext.c: libssh network transport provider
+ *
+ * Copyright (C) 2012 Red Hat, Inc.
+ *
+ * This 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.
+ *
+ * This 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 this library;  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * Author: Peter Krempa <pkrempa redhat com>
+ */
+#include <config.h>
+#include <libssh2.h>
+#include <libssh2_publickey.h>
+
+#include "virnetlibsshcontext.h"
+
+#include "internal.h"
+#include "buf.h"
+#include "memory.h"
+#include "logging.h"
+#include "configmake.h"
+#include "threads.h"
+#include "util.h"
+#include "virterror_internal.h"
+
+#define VIR_FROM_THIS VIR_FROM_LIBSSH
+
+static const char
+vir_libssh2_key_comment[] = "added by libvirt libssh2 transport";
+#define VIR_NET_LIBSSH_BUFFER_SIZE  1024
+
+typedef enum {
+    VIR_NET_LIBSSH_STATE_NEW,
+    VIR_NET_LIBSSH_STATE_HANDSHAKE_COMPLETE,
+    VIR_NET_LIBSSH_STATE_AUTH_CALLBACK_ERROR,
+    VIR_NET_LIBSSH_STATE_CLOSED,
+    VIR_NET_LIBSSH_STATE_ERROR,
+    VIR_NET_LIBSSH_STATE_ERROR_REMOTE,
+} virNetLibSSHSessionState;
+
+typedef enum {
+    VIR_NET_LIBSSH_AUTHCB_OK,
+    VIR_NET_LIBSSH_AUTHCB_NO_METHOD,
+    VIR_NET_LIBSSH_AUTHCB_OOM,
+    VIR_NET_LIBSSH_AUTHCB_RETR_ERR,
+} virNetLibSSHAuthCallbackError;
+
+typedef enum {
+    VIR_NET_LIBSSH_AUTH_KEYBOARD_INTERACTIVE,
+    VIR_NET_LIBSSH_AUTH_PASSWORD,
+    VIR_NET_LIBSSH_AUTH_PRIVKEY,
+    VIR_NET_LIBSSH_AUTH_AGENT
+} virNetLibSSHAuthMethods;
+
+
+typedef struct _virNetLibSSHAuthMethod virNetLibSSHAuthMethod;
+typedef virNetLibSSHAuthMethod *virNetLibSSHAuthMethodPtr;
+
+struct _virNetLibSSHAuthMethod {
+    virNetLibSSHAuthMethods method;
+    const char *username;
+    const char *password;
+    const char *filename;
+
+    int tries;
+};
+
+struct _virNetLibSSHSession {
+    virNetLibSSHSessionState state;
+    virMutex lock;
+
+    /* libssh2 internal stuff */
+    LIBSSH2_SESSION *session;
+    LIBSSH2_CHANNEL *channel;
+    LIBSSH2_KNOWNHOSTS *knownHosts;
+    LIBSSH2_AGENT *agent;
+
+    /* for host key checking */
+    virNetLibSSHHostkeyVerify hostKeyVerify;
+    const char *knownHostsFile;
+    const char *hostname;
+    int port;
+
+    /* authentication stuff */
+    virConnectAuthPtr cred;
+    virNetLibSSHAuthCallbackError authCbErr;
+    size_t nauths;
+    virNetLibSSHAuthMethodPtr *auths;
+
+    /* channel stuff */
+    const char *channelCommand;
+    int channelCommandReturnValue;
+
+    /* read cache */
+    char rbuf[VIR_NET_LIBSSH_BUFFER_SIZE];
+    size_t bufUsed;
+    size_t bufStart;
+};
+
+static virNetLibSSHAuthMethodPtr
+virNetLibSSHSessionAuthMethodNew(virNetLibSSHSessionPtr sess)
+{
+    virNetLibSSHAuthMethodPtr auth;
+
+    if (VIR_ALLOC(auth) < 0)
+        goto error;
+
+    if (VIR_EXPAND_N(sess->auths, sess->nauths, 1) < 0)
+        goto error;
+
+    sess->auths[sess->nauths - 1] = auth;
+
+    return auth;
+
+error:
+    VIR_FREE(auth);
+    return NULL;
+}
+
+static void
+virNetLibSSHSessionAuthMethodsFree(virNetLibSSHSessionPtr sess)
+{
+    int i;
+
+    for (i = 0; i < sess->nauths; i++) {
+        VIR_FREE(sess->auths[i]->username);
+        VIR_FREE(sess->auths[i]->password);
+        VIR_FREE(sess->auths[i]->filename);
+        VIR_FREE(sess->auths[i]);
+    }
+
+    VIR_FREE(sess->auths);
+    sess->nauths = 0;
+}
+
+/* keyboard interactive authentication callback */
+static void
+virNetLibSSHKbIntCb(const char *name ATTRIBUTE_UNUSED,
+                    int name_len ATTRIBUTE_UNUSED,
+                    const char *instruction ATTRIBUTE_UNUSED,
+                    int instruction_len ATTRIBUTE_UNUSED,
+                    int num_prompts,
+                    const LIBSSH2_USERAUTH_KBDINT_PROMPT *prompts,
+                    LIBSSH2_USERAUTH_KBDINT_RESPONSE *responses,
+                    void **opaque)
+{
+    virNetLibSSHSessionPtr priv = *opaque;
+    virConnectCredentialPtr askcred = NULL;
+    int i;
+    int credtype_echo = -1;
+    int credtype_noecho = -1;
+    char *tmp;
+
+    priv->authCbErr = VIR_NET_LIBSSH_AUTHCB_OK;
+
+    /* find credential type for asking passwords */
+    for (i = 0; i < priv->cred->ncredtype; i++) {
+        if (priv->cred->credtype[i] == VIR_CRED_PASSPHRASE ||
+            priv->cred->credtype[i] == VIR_CRED_NOECHOPROMPT)
+            credtype_noecho = priv->cred->credtype[i];
+
+        if (priv->cred->credtype[i] == VIR_CRED_ECHOPROMPT)
+            credtype_echo = priv->cred->credtype[i];
+    }
+
+    if (credtype_echo < 0 || credtype_noecho < 0) {
+        priv->authCbErr = VIR_NET_LIBSSH_AUTHCB_NO_METHOD;
+        return;
+    }
+
+    if (VIR_ALLOC_N(askcred, num_prompts) < 0) {
+        priv->authCbErr = VIR_NET_LIBSSH_AUTHCB_OOM;
+        return;
+    }
+
+    /* fill data structures for auth callback */
+    for (i = 0; i < num_prompts; i++) {
+        /* remove colon and trailing spaces from prompts, as default behavior
+         * of libvirt's auth callback is to add them */
+        if ((tmp = strrchr(prompts[i].text, ':')))
+            *tmp = '\0';
+
+        askcred[i].prompt = prompts[i].text;
+        askcred[i].type = prompts[i].echo ? credtype_echo : credtype_noecho;
+    }
+
+    /* retrieve responses using the auth callback */
+    if (priv->cred->cb(askcred, num_prompts, priv->cred->cbdata)) {
+        priv->authCbErr = VIR_NET_LIBSSH_AUTHCB_RETR_ERR;
+        goto cleanup;
+    }
+
+    /* copy retrieved data back */
+    for (i = 0; i < num_prompts; i++) {
+        responses[i].text = askcred[i].result;
+        askcred[i].result = NULL; /* steal the pointer */
+        responses[i].length = askcred[i].resultlen;
+    }
+
+cleanup:
+    if (askcred)
+        for (i = 0; i < num_prompts; i++)
+            VIR_FREE(askcred[i].result);
+
+    VIR_FREE(askcred);
+
+    return;
+}
+
+/* check session host keys
+ *
+ * this function checks the known host database and verifies the key
+ * errors are raised in this func
+ *
+ * return value: 0 on success, not 0 otherwise
+ */
+static int
+virNetLibSSHCheckHostKey(virNetLibSSHSessionPtr sess)
+{
+    int ret;
+    const char *key;
+    const char *keyhash;
+    int keyType;
+    size_t keyLength;
+    char *errmsg;
+    virBuffer buff = VIR_BUFFER_INITIALIZER;
+    virConnectCredential askKey;
+    struct libssh2_knownhost *knownHostEntry = NULL;
+    int i;
+    char *hostnameStr = NULL;
+
+    if (sess->hostKeyVerify == VIR_NET_LIBSSH_HOSTKEY_VERIFY_IGNORE)
+        return 0;
+
+    /* get the key */
+    key = libssh2_session_hostkey(sess->session, &keyLength, &keyType);
+    if (!key) {
+        libssh2_session_last_error(sess->session, &errmsg, NULL, 0);
+        virReportError(VIR_ERR_LIBSSH_ERROR,
+                       _("Failed to retrieve ssh host key: %s"),
+                       errmsg);
+        return -1;
+    }
+
+    /* verify it */
+    ret = libssh2_knownhost_checkp(sess->knownHosts,
+                                   sess->hostname,
+                                   sess->port,
+                                   key,
+                                   keyLength,
+                                   LIBSSH2_KNOWNHOST_TYPE_PLAIN |
+                                   LIBSSH2_KNOWNHOST_KEYENC_RAW,
+                                   &knownHostEntry);
+
+    switch (ret) {
+    case LIBSSH2_KNOWNHOST_CHECK_NOTFOUND:
+        /* key was not found, query to add it to database */
+        if (sess->hostKeyVerify == VIR_NET_LIBSSH_HOSTKEY_VERIFY_NORMAL) {
+            /* ask to add the key */
+            if (!sess->cred || !sess->cred->cb) {
+                virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                               _("No user interaction callback provided: "
+                                 "Can't verify the session host key"));
+                return -1;
+            }
+
+            /* prepare data for the callback */
+            memset(&askKey, 0, sizeof(virConnectCredential));
+
+            for (i = 0; i < sess->cred->ncredtype; i++) {
+                if (sess->cred->credtype[i] == VIR_CRED_ECHOPROMPT) {
+                    i = -1;
+                    break;
+                }
+            }
+
+            if (i > 0) {
+                virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                               _("no suitable method to retrieve "
+                                 "authentication cretentials"));
+                return -1;
+            }
+
+            /* calculate remote key hash, using MD5 algorithm that is
+             * usual in OpenSSH. The returned value should *NOT* be freed*/
+            if (!(keyhash = libssh2_hostkey_hash(sess->session,
+                                                 LIBSSH2_HOSTKEY_HASH_MD5))) {
+                virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                               _("failed to calculate ssh host key hash"));
+                return -1;
+            }
+            /* format the host key into a nice userfriendly string.
+             * Sadly, there's no constant to describe the hash length, so
+             * we have to use a *MAGIC* constant. */
+            for (i = 0; i < 16; i++) {
+                virBufferAsprintf(&buff, "%02X", (unsigned char) keyhash[i]);
+                if (i != 15)
+                    virBufferAddChar(&buff, ':');
+            }
+
+            if (virBufferError(&buff) != 0) {
+                virReportOOMError();
+                return -1;
+            }
+
+            keyhash = virBufferContentAndReset(&buff);
+
+            askKey.type = VIR_CRED_ECHOPROMPT;
+            if (virAsprintf((char **)&askKey.prompt,
+                            _("Accept SSH host key with hash '%s' for "
+                              "host '%s:%d' (%s/%s)?"),
+                            keyhash,
+                            sess->hostname, sess->port,
+                            _("yes"), _("no")) < 0) {
+                virReportOOMError();
+                VIR_FREE(keyhash);
+                return -1;
+            }
+
+            if (sess->cred->cb(&askKey, 1, sess->cred->cbdata)) {
+                virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                               _("failed to retrieve decision to accept "
+                                 "host key"));
+                VIR_FREE(askKey.prompt);
+                VIR_FREE(keyhash);
+                return -1;
+            }
+
+            VIR_FREE(askKey.prompt);
+
+            if (STRNEQ_NULLABLE(askKey.result, _("yes"))) {
+                virReportError(VIR_ERR_LIBSSH_ERROR,
+                               _("SSH host key for '%s' (%s) was not accepted"),
+                            sess->hostname, keyhash);
+                VIR_FREE(keyhash);
+                VIR_FREE(askKey.result);
+                return -1;
+            }
+            VIR_FREE(keyhash);
+            VIR_FREE(askKey.result);
+        }
+
+        /* VIR_NET_LIBSSH_HOSTKEY_VERIFY_AUTO_ADD */
+        /* convert key type, as libssh is using different enums type for
+         * getting the key and different for adding ... */
+        switch (keyType) {
+        case LIBSSH2_HOSTKEY_TYPE_RSA:
+            keyType = LIBSSH2_KNOWNHOST_KEY_SSHRSA;
+            break;
+        case LIBSSH2_HOSTKEY_TYPE_DSS:
+            keyType = LIBSSH2_KNOWNHOST_KEY_SSHDSS;
+
+        case LIBSSH2_HOSTKEY_TYPE_UNKNOWN:
+        default:
+            virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                           _("unsupported SSH key type"));
+            return -1;
+        }
+
+        /* add the key to the DB and save it, if applicable */
+        /* construct a "[hostname]:port" string to have the hostkey bound
+         * to port number */
+        virBufferAsprintf(&buff, "[%s]:%d", sess->hostname, sess->port);
+
+        if (virBufferError(&buff) != 0) {
+            virReportOOMError();
+            return -1;
+        }
+
+        hostnameStr = virBufferContentAndReset(&buff);
+
+        if (libssh2_knownhost_addc(sess->knownHosts,
+                                   hostnameStr,
+                                   NULL,
+                                   key,
+                                   keyLength,
+                                   vir_libssh2_key_comment,
+                                   strlen(vir_libssh2_key_comment),
+                                   LIBSSH2_KNOWNHOST_TYPE_PLAIN |
+                                   LIBSSH2_KNOWNHOST_KEYENC_RAW |
+                                   keyType,
+                                   NULL) < 0) {
+            libssh2_session_last_error(sess->session, &errmsg, NULL, 0);
+            virReportError(VIR_ERR_LIBSSH_ERROR,
+                           _("unable to add SSH host key for host '%s': %s"),
+                           hostnameStr, errmsg);
+            VIR_FREE(hostnameStr);
+            return -1;
+        }
+
+        VIR_FREE(hostnameStr);
+
+        /* write the host key file - if applicable */
+        if (sess->knownHostsFile) {
+            if (libssh2_knownhost_writefile(sess->knownHosts,
+                                            sess->knownHostsFile,
+                                         LIBSSH2_KNOWNHOST_FILE_OPENSSH) < 0) {
+                libssh2_session_last_error(sess->session, &errmsg, NULL, 0);
+                virReportError(VIR_ERR_LIBSSH_ERROR,
+                               _("failed to write known_host file '%s': %s"),
+                               sess->knownHostsFile,
+                               errmsg);
+                return -1;
+            }
+        }
+        /* key was accepted and added */
+        return 0;
+
+    case LIBSSH2_KNOWNHOST_CHECK_MATCH:
+        /* host key matches */
+        return 0;
+
+    case LIBSSH2_KNOWNHOST_CHECK_MISMATCH:
+        /* host key verification failed */
+        virReportError(VIR_ERR_AUTH_FAILED,
+                       _("!!! SSH HOST KEY VERIFICATION FAILED !!!: "
+                         "Identity of host '%s:%d' differs from stored identity. "
+                         "Please verify the new host key '%s' to avoid possible "
+                         "man in the middle attack. The key is stored in '%s'."),
+                       sess->hostname, sess->port,
+                       knownHostEntry->key, sess->knownHostsFile);
+        return -1;
+
+    case LIBSSH2_KNOWNHOST_CHECK_FAILURE:
+        libssh2_session_last_error(sess->session, &errmsg, NULL, 0);
+        virReportError(VIR_ERR_LIBSSH_ERROR,
+                       _("failed to validate SSH host key: %s"),
+                       errmsg);
+        return -1;
+
+    default: /* should never happen (tm) */
+        virReportError(VIR_ERR_LIBSSH_ERROR, "%s", _("Unknown error value"));
+        return -1;
+    }
+
+    return -1;
+}
+
+/* perform ssh agent authentication
+ *
+ * Returns: 0 on success
+ *          1 on authentication failure
+ *         -1 on error
+ */
+static int
+virNetLibSSHAuthenticateAgent(virNetLibSSHSessionPtr sess,
+                              virNetLibSSHAuthMethodPtr priv)
+{
+    struct libssh2_agent_publickey *agent_identity;
+    struct libssh2_agent_publickey *agent_prev_identity = NULL;
+    int ret;
+    char *errmsg;
+
+    if (libssh2_agent_connect(sess->agent) >= 0) {
+        virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                       _("Failed to connect to ssh agent"));
+        return 1;
+    }
+
+    if (libssh2_agent_list_identities(sess->agent) < 0) {
+        virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                       _("Failed to list ssh agent identities"));
+        return 1;
+    }
+
+    while (!(ret = libssh2_agent_get_identity(sess->agent,
+                                              &agent_identity,
+                                              agent_prev_identity))) {
+        if (!(ret = libssh2_agent_userauth(sess->agent,
+                                           priv->username,
+                                           agent_identity)))
+            return 0; /* key accepted */
+
+        if (ret != LIBSSH2_ERROR_AUTHENTICATION_FAILED) {
+            libssh2_session_last_error(sess->session, &errmsg, NULL, 0);
+            virReportError(VIR_ERR_AUTH_FAILED,
+                           _("failed to authenticate using SSH agent: %s"),
+                           errmsg);
+            return -1;
+        }
+        /* authentication has failed, try next key */
+    }
+
+    /* if there are no more keys in the agent, the identity retrieval
+     * function returns > 1 */
+    libssh2_session_last_error(sess->session, &errmsg, NULL, 0);
+    virReportError(VIR_ERR_AUTH_FAILED,
+                   _("failed to authenticate using SSH agent: %s"),
+                   errmsg);
+
+    if (ret < 0)
+        return -1;
+    else
+        return 1;
+}
+
+/* perform private key authentication
+ *
+ * Returns: 0 on success
+ *          1 on authentication failure
+ *         -1 on error
+ */
+static int
+virNetLibSSHAuthenticatePrivkey(virNetLibSSHSessionPtr sess,
+                                virNetLibSSHAuthMethodPtr priv)
+{
+    virConnectCredential retr_passphrase;
+    int i;
+    char *errmsg;
+    int ret;
+
+    /* try open the key with no password */
+    if ((ret = libssh2_userauth_publickey_fromfile(sess->session,
+                                                   priv->username,
+                                                   NULL,
+                                                   priv->filename,
+                                                   priv->password)) == 0)
+        return 0; /* success */
+
+    if (priv->password ||
+        ret == LIBSSH2_ERROR_PUBLICKEY_UNRECOGNIZED ||
+        ret == LIBSSH2_ERROR_AUTHENTICATION_FAILED) {
+        libssh2_session_last_error(sess->session, &errmsg, NULL, 0);
+        virReportError(VIR_ERR_AUTH_FAILED,
+                       _("authentication with private key '%s' "
+                         "has failed: %s"),
+                       priv->filename, errmsg);
+        return 1; /* auth failed */
+    }
+
+    /* request user's key password */
+    if (!sess->cred || !sess->cred->cb) {
+        virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                       _("No user interaction callback provided: "
+                         "Can't retrieve private key passphrase"));
+        return -1;
+    }
+
+    memset(&retr_passphrase, 0, sizeof(virConnectCredential));
+    retr_passphrase.type = -1;
+
+    for (i = 0; i < sess->cred->ncredtype; i++) {
+        if (sess->cred->credtype[i] == VIR_CRED_PASSPHRASE ||
+            sess->cred->credtype[i] == VIR_CRED_NOECHOPROMPT) {
+            retr_passphrase.type = sess->cred->credtype[i];
+            break;
+        }
+    }
+
+    if (retr_passphrase.type < 0) {
+        virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                       _("no suitable method to retrieve key passphrase"));
+        return -1;
+    }
+
+    if (virAsprintf((char **)&retr_passphrase.prompt,
+                    _("Passphrase for key '%s'"),
+                    priv->filename) < 0) {
+        virReportOOMError();
+        return -1;
+    }
+
+    if (sess->cred->cb(&retr_passphrase, 1, sess->cred->cbdata)) {
+        virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                       _("failed to retrieve private key passphrase: "
+                         "callback has failed"));
+        VIR_FREE(retr_passphrase.prompt);
+        return -1;
+    }
+
+    VIR_FREE(retr_passphrase.prompt);
+
+    ret = libssh2_userauth_publickey_fromfile(sess->session,
+                                              priv->username,
+                                              NULL,
+                                              priv->filename,
+                                              retr_passphrase.result);
+
+    VIR_FREE(retr_passphrase.result);
+
+    if (ret < 0) {
+        libssh2_session_last_error(sess->session, &errmsg, NULL, 0);
+        virReportError(VIR_ERR_AUTH_FAILED,
+                       _("authentication with private key '%s' "
+                         "has failed: %s"),
+                       priv->filename, errmsg);
+
+        if (ret == LIBSSH2_ERROR_PUBLICKEY_UNRECOGNIZED ||
+            ret == LIBSSH2_ERROR_AUTHENTICATION_FAILED)
+            return 1;
+        else
+            return -1;
+    }
+
+    return 0;
+}
+
+/* perform tunelled password authentication
+ *
+ * Returns: 0 on success
+ *          1 on authentication failure
+ *         -1 on error
+ */
+static int
+virNetLibSSHAuthenticatePassword(virNetLibSSHSessionPtr sess,
+                                 virNetLibSSHAuthMethodPtr priv)
+{
+    char *errmsg;
+    int ret;
+
+    /* tunelled password authentication */
+    if ((ret = libssh2_userauth_password(sess->session,
+                                         priv->username,
+                                         priv->password)) < 0) {
+        libssh2_session_last_error(sess->session, &errmsg, NULL, 0);
+        virReportError(VIR_ERR_AUTH_FAILED,
+                       _("tunelled password authentication failed: %s"),
+                       errmsg);
+
+        if (ret == LIBSSH2_ERROR_AUTHENTICATION_FAILED)
+            return 1;
+        else
+            return -1;
+    }
+    /* auth success */
+    return 0;
+}
+
+/* perform keyboard interactive authentication
+ *
+ * Returns: 0 on success
+ *          1 on authentication failure
+ *         -1 on error
+ */
+static int
+virNetLibSSHAuthenticateKeyboardInteractive(virNetLibSSHSessionPtr sess,
+                                            virNetLibSSHAuthMethodPtr priv)
+{
+    char *errmsg;
+    int ret;
+
+    if (!sess->cred || !sess->cred->cb) {
+        virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                       _("Can't perform keyboard-interactive authentication: "
+                         "Authentication callback not provided "));
+        return -1;
+    }
+
+    /* try the auth infinite number of times, the server should break the
+     * connection if maximum number of bad auth tries is exceeded */
+    while (priv->tries < 0 || priv->tries-- > 0) {
+        ret = libssh2_userauth_keyboard_interactive(sess->session,
+                                                    priv->username,
+                                                    virNetLibSSHKbIntCb);
+
+        /* check for errors while calling the callback */
+        switch (sess->authCbErr) {
+        case VIR_NET_LIBSSH_AUTHCB_NO_METHOD:
+            virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                           _("no suitable method to retrieve "
+                             "authentication cretentials"));
+            return -1;
+        case VIR_NET_LIBSSH_AUTHCB_OOM:
+            virReportOOMError();
+            return -1;
+        case VIR_NET_LIBSSH_AUTHCB_RETR_ERR:
+            virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                           _("failed to retrieve credentials"));
+            return -1;
+        case VIR_NET_LIBSSH_AUTHCB_OK:
+            /* everything went fine, let's continue */
+            break;
+        }
+
+        if (ret == 0)
+            /* authentication succeeded */
+            return 0;
+
+        if (ret == LIBSSH2_ERROR_AUTHENTICATION_FAILED)
+            continue; /* try again */
+
+        if (ret < 0) {
+            libssh2_session_last_error(sess->session, &errmsg, NULL, 0);
+            virReportError(VIR_ERR_AUTH_FAILED,
+                           _("keyboard interactive authentication failed: %s"),
+                           errmsg);
+            return -1;
+        }
+    }
+    libssh2_session_last_error(sess->session, &errmsg, NULL, 0);
+    virReportError(VIR_ERR_AUTH_FAILED,
+                   _("keyboard interactive authentication failed: %s"),
+                   errmsg);
+    return 1;
+}
+
+/* select auth method and authenticate */
+static int
+virNetLibSSHAuthenticate(virNetLibSSHSessionPtr sess)
+{
+    virNetLibSSHAuthMethodPtr auth;
+    bool no_method = false;
+    bool auth_failed = false;
+    char *auth_list;
+    char *errmsg;
+    int i;
+    int ret;
+
+    if (!sess->nauths) {
+        virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                       _("No authentication methods and credentials "
+                         "provided"));
+        return -1;
+    }
+
+    /* obtain list of supported auth methods */
+    auth_list = libssh2_userauth_list(sess->session,
+                                      sess->auths[0]->username,
+                                      strlen(sess->auths[0]->username));
+    if (!auth_list) {
+        /* unlikely event, authentication succeeded with NONE as method */
+        if (libssh2_userauth_authenticated(sess->session) == 1)
+            return 0;
+
+        libssh2_session_last_error(sess->session, &errmsg, NULL, 0);
+        virReportError(VIR_ERR_LIBSSH_ERROR,
+                       _("couldn't retrieve authentication methods list: %s"),
+                       errmsg);
+        return -1;
+    }
+
+    for (i = 0; i < sess->nauths; i++) {
+        auth = sess->auths[i];
+
+        ret = 2;
+        virResetLastError();
+
+        switch (auth->method) {
+        case VIR_NET_LIBSSH_AUTH_KEYBOARD_INTERACTIVE:
+            if (strstr(auth_list, "keyboard-interactive"))
+                ret = virNetLibSSHAuthenticateKeyboardInteractive(sess, auth);
+            break;
+        case VIR_NET_LIBSSH_AUTH_AGENT:
+            if (strstr(auth_list, "publickey"))
+                ret = virNetLibSSHAuthenticateAgent(sess, auth);
+            break;
+        case VIR_NET_LIBSSH_AUTH_PRIVKEY:
+            if (strstr(auth_list, "publickey"))
+                ret = virNetLibSSHAuthenticatePrivkey(sess, auth);
+            break;
+        case VIR_NET_LIBSSH_AUTH_PASSWORD:
+            if (strstr(auth_list, "password"))
+                ret = virNetLibSSHAuthenticatePassword(sess, auth);
+            break;
+        }
+
+        /* return on success or error */
+        if (ret <= 0)
+            return ret;
+
+        /* the authentication method is not supported */
+        if (ret == 2)
+            no_method = true;
+
+        /* authentication with this method has failed */
+        if (ret == 1)
+            auth_failed = true;
+    }
+
+    if (no_method && !auth_failed) {
+        virReportError(VIR_ERR_AUTH_FAILED, "%s",
+                       _("None of the requested authentication methods "
+                         "are supported by the server"));
+    } else {
+        virReportError(VIR_ERR_AUTH_FAILED, "%s",
+                       _("All provided authentication methods with credentials "
+                         "were rejected by the server"));
+    }
+
+    return -1;
+}
+
+/* open channel */
+static int
+virNetLibSSHOpenChannel(virNetLibSSHSessionPtr sess)
+{
+    char *errmsg;
+
+    sess->channel = libssh2_channel_open_session(sess->session);
+    if (!sess->channel) {
+        libssh2_session_last_error(sess->session, &errmsg, NULL, 0);
+        virReportError(VIR_ERR_LIBSSH_ERROR,
+                       _("failed to open ssh channel: %s"),
+                       errmsg);
+        return -1;
+    }
+
+    if (libssh2_channel_exec(sess->channel, sess->channelCommand) != 0) {
+        libssh2_session_last_error(sess->session, &errmsg, NULL, 0);
+        virReportError(VIR_ERR_LIBSSH_ERROR,
+                       _("failed to execute command '%s': %s"),
+                       sess->channelCommand,
+                       errmsg);
+        return -1;
+    }
+
+    /* nonblocking mode - currently does nothing*/
+    libssh2_channel_set_blocking(sess->channel, 0);
+
+    /* channel open */
+    return 0;
+}
+
+/* validate if all required parameters are configured */
+static int
+virNetLibSSHValidateConfig(virNetLibSSHSessionPtr sess)
+{
+    if (sess->nauths == 0) {
+        virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                       _("No authentication methods and credentials "
+                         "provided"));
+        return -1;
+    }
+
+    if (!sess->channelCommand) {
+        virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                       _("No channel command provided"));
+        return -1;
+    }
+
+    if (sess->hostKeyVerify != VIR_NET_LIBSSH_HOSTKEY_VERIFY_IGNORE) {
+        if (!sess->hostname) {
+            virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                           _("Hostname is needed for host key verification"));
+            return -1;
+        }
+    }
+
+    /* everything ok */
+    return 0;
+}
+
+/* ### PUBLIC API ### */
+int
+virNetLibSSHSessionAuthSetCallback(virNetLibSSHSessionPtr sess,
+                                   virConnectAuthPtr auth)
+{
+    virMutexLock(&sess->lock);
+    sess->cred = auth;
+    virMutexUnlock(&sess->lock);
+    return 0;
+}
+
+void
+virNetLibSSHSessionAuthReset(virNetLibSSHSessionPtr sess)
+{
+    virMutexLock(&sess->lock);
+    virNetLibSSHSessionAuthMethodsFree(sess);
+    virMutexUnlock(&sess->lock);
+}
+
+int
+virNetLibSSHSessionAuthAddPasswordAuth(virNetLibSSHSessionPtr sess,
+                                       const char *username,
+                                       const char *password)
+{
+    virNetLibSSHAuthMethodPtr auth;
+    char *user = NULL;
+    char *pass = NULL;
+
+    if (!username || !password) {
+        virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                       _("Username and password must be provided "
+                         "for password authentication"));
+        return -1;
+    }
+
+    virMutexLock(&sess->lock);
+
+    if (!(user = strdup(username)) ||
+        !(pass = strdup(password)))
+        goto no_memory;
+
+    if (!(auth = virNetLibSSHSessionAuthMethodNew(sess)))
+        goto no_memory;
+
+    auth->username = user;
+    auth->password = pass;
+    auth->method = VIR_NET_LIBSSH_AUTH_PASSWORD;
+
+    virMutexUnlock(&sess->lock);
+    return 0;
+
+no_memory:
+    VIR_FREE(user);
+    VIR_FREE(pass);
+    virReportOOMError();
+    virMutexUnlock(&sess->lock);
+    return -1;
+}
+
+int
+virNetLibSSHSessionAuthAddAgentAuth(virNetLibSSHSessionPtr sess,
+                                    const char *username)
+{
+    virNetLibSSHAuthMethodPtr auth;
+    char *user = NULL;
+
+    if (!username) {
+        virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                       _("Username must be provided "
+                         "for ssh agent authentication"));
+        return -1;
+    }
+
+    virMutexLock(&sess->lock);
+
+    if (!(user = strdup(username)))
+        goto no_memory;
+
+
+    if (!(auth = virNetLibSSHSessionAuthMethodNew(sess))) {
+        virReportOOMError();
+        virMutexUnlock(&sess->lock);
+        return -1;
+    }
+
+    auth->username = user;
+    auth->method = VIR_NET_LIBSSH_AUTH_AGENT;
+
+    virMutexUnlock(&sess->lock);
+    return 0;
+
+no_memory:
+    VIR_FREE(user);
+    virReportOOMError();
+    virMutexUnlock(&sess->lock);
+    return -1;
+}
+
+int
+virNetLibSSHSessionAuthAddPrivKeyAuth(virNetLibSSHSessionPtr sess,
+                                      const char *username,
+                                      const char *keyfile,
+                                      const char *password)
+{
+    virNetLibSSHAuthMethodPtr auth;
+
+    char *user = NULL;
+    char *pass = NULL;
+    char *file = NULL;
+
+    if (!username || !keyfile) {
+        virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                       _("Username and key file path must be provided "
+                         "for private key authentication"));
+        return -1;
+    }
+
+    virMutexLock(&sess->lock);
+
+    if (!(user = strdup(username)) ||
+        !(file = strdup(keyfile)))
+        goto no_memory;
+
+    if (password) {
+        if (!(pass = strdup(password)))
+            goto no_memory;
+    }
+
+    if (!(auth = virNetLibSSHSessionAuthMethodNew(sess)))
+        goto no_memory;
+
+    auth->username = user;
+    auth->password = pass;
+    auth->filename = file;
+    auth->method = VIR_NET_LIBSSH_AUTH_PRIVKEY;
+
+    virMutexUnlock(&sess->lock);
+    return 0;
+
+no_memory:
+    VIR_FREE(user);
+    VIR_FREE(pass);
+    VIR_FREE(file);
+    virReportOOMError();
+    virMutexUnlock(&sess->lock);
+    return -1;
+}
+
+int
+virNetLibSSHSessionAuthAddKeyboardAuth(virNetLibSSHSessionPtr sess,
+                                       const char *username,
+                                       int tries)
+{
+    virNetLibSSHAuthMethodPtr auth;
+    char *user = NULL;
+
+    if (!username) {
+        virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                       _("Username must be provided "
+                         "for ssh agent authentication"));
+        return -1;
+    }
+
+    virMutexLock(&sess->lock);
+
+    if (!(user = strdup(username)))
+        goto no_memory;
+
+
+    if (!(auth = virNetLibSSHSessionAuthMethodNew(sess))) {
+        virReportOOMError();
+        virMutexUnlock(&sess->lock);
+        return -1;
+    }
+
+    auth->username = user;
+    auth->tries = tries;
+    auth->method = VIR_NET_LIBSSH_AUTH_KEYBOARD_INTERACTIVE;
+
+    virMutexUnlock(&sess->lock);
+    return 0;
+
+no_memory:
+    VIR_FREE(user);
+    virReportOOMError();
+    virMutexUnlock(&sess->lock);
+    return -1;
+
+}
+
+int
+virNetLibSSHSessionSetChannelCommand(virNetLibSSHSessionPtr sess,
+                                     const char *command)
+{
+    virMutexLock(&sess->lock);
+
+    VIR_FREE(sess->channelCommand);
+
+    if (command && !(sess->channelCommand = strdup(command))) {
+        virReportOOMError();
+        virMutexUnlock(&sess->lock);
+        return -1;
+    }
+
+    virMutexUnlock(&sess->lock);
+    return 0;
+}
+
+int
+virNetLibSSHSessionSetHostKeyVerification(virNetLibSSHSessionPtr sess,
+                                          const char *hostname,
+                                          int port,
+                                          const char *hostsfile,
+                                          bool readonly,
+                                          virNetLibSSHHostkeyVerify opt)
+{
+    char *errmsg;
+
+    virMutexLock(&sess->lock);
+
+    sess->port = port;
+    sess->hostKeyVerify = opt;
+
+    VIR_FREE(sess->hostname);
+
+    if (hostname && !(sess->hostname = strdup(hostname)))
+        goto no_memory;
+
+    /* load the known hosts file */
+    if (hostsfile) {
+        if (libssh2_knownhost_readfile(sess->knownHosts,
+                                       hostsfile,
+                                       LIBSSH2_KNOWNHOST_FILE_OPENSSH) < 0) {
+            libssh2_session_last_error(sess->session, &errmsg, NULL, 0);
+            virReportError(VIR_ERR_LIBSSH_ERROR,
+                           _("unable to load knownhosts file '%s': %s"),
+                           hostsfile, errmsg);
+        }
+
+        /* set filename only if writing to the known hosts file is requested */
+
+        if (!readonly) {
+            VIR_FREE(sess->knownHostsFile);
+            if ((sess->knownHostsFile = strdup(hostsfile)) == NULL)
+                goto no_memory;
+        }
+    }
+
+    virMutexUnlock(&sess->lock);
+    return 0;
+
+no_memory:
+    virMutexUnlock(&sess->lock);
+    virReportOOMError();
+    return -1;
+}
+
+/* allocate and initialize a ssh session object */
+virNetLibSSHSessionPtr virNetLibSSHSessionNew(void)
+{
+    virNetLibSSHSessionPtr sess;
+    if (VIR_ALLOC(sess) < 0)
+        return NULL;
+
+    /* initialize internal structures */
+    if (virMutexInit(&sess->lock) < 0) {
+        virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                       _("Failed to initialize mutex"));
+        goto error;
+    }
+
+    /* initialize session data, use the internal data for callbacks
+     * and stick to default memory management functions */
+    if (!(sess->session = libssh2_session_init_ex(NULL,
+                                                  NULL,
+                                                  NULL,
+                                                  (void *)sess))) {
+        virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                       _("Failed to initialize libssh2 session"));
+        goto error;
+    }
+
+    if (!(sess->knownHosts = libssh2_knownhost_init(sess->session))) {
+        virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                       _("Failed to initialize libssh2 known hosts table"));
+        goto error;
+    }
+
+    if (!(sess->agent = libssh2_agent_init(sess->session))) {
+        virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                       _("Failed to initialize libssh2 agent handle"));
+        goto error;
+    }
+
+    VIR_DEBUG("virNetLibSSHSessionPtr=0x%p, LIBSSH2_SESSION *=0x%p",
+              sess,
+              sess->session);
+
+    /* set blocking mode for libssh2 until handshake is complete */
+    libssh2_session_set_blocking(sess->session, 1);
+
+    /* default states for config variables */
+    sess->state = VIR_NET_LIBSSH_STATE_NEW;
+    sess->hostKeyVerify = VIR_NET_LIBSSH_HOSTKEY_VERIFY_IGNORE;
+
+    return sess;
+
+error:
+    libssh2_agent_free(sess->agent);
+    libssh2_knownhost_free(sess->knownHosts);
+    libssh2_session_free(sess->session);
+    VIR_FREE(sess);
+    return NULL;
+}
+
+/* close session and free internal data */
+void
+virNetLibSSHSessionFree(virNetLibSSHSessionPtr sess)
+{
+    VIR_DEBUG("sess=0x%p", sess);
+
+    if (!sess)
+        return;
+
+    virMutexLock(&sess->lock);
+
+    if (sess->channel) {
+        libssh2_channel_send_eof(sess->channel);
+        libssh2_channel_close(sess->channel);
+        libssh2_channel_free(sess->channel);
+    }
+
+    libssh2_knownhost_free(sess->knownHosts);
+    libssh2_agent_free(sess->agent);
+
+    if (sess->session) {
+        libssh2_session_disconnect(sess->session,
+                                   "libvirt: virNetLibSSHSessionFree()");
+        libssh2_session_free(sess->session);
+    }
+
+    virNetLibSSHSessionAuthMethodsFree(sess);
+
+    VIR_FREE(sess->channelCommand);
+    VIR_FREE(sess->hostname);
+    VIR_FREE(sess->knownHostsFile);
+
+    VIR_FREE(sess);
+}
+
+int
+virNetLibSSHSessionConnect(virNetLibSSHSessionPtr sess,
+                           int sock)
+{
+    int ret;
+    char *errmsg;
+
+    VIR_DEBUG("sess=0x%p, sock=%d", sess, sock);
+
+    if (!sess || sess->state != VIR_NET_LIBSSH_STATE_NEW) {
+        virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                       _("Invalid virNetLibSSHSessionPtr"));
+        return -1;
+    }
+
+    virMutexLock(&sess->lock);
+
+    /* check if configuration is valid */
+    if ((ret = virNetLibSSHValidateConfig(sess)) < 0)
+        goto error;
+
+    /* open session */
+    ret = libssh2_session_handshake(sess->session, sock);
+    /* libssh2 is in blocking mode, so EAGAIN will never happen */
+    if (ret < 0) {
+        libssh2_session_last_error(sess->session, &errmsg, NULL, 0);
+        virReportError(VIR_ERR_NO_CONNECT,
+                       _("SSH session handshake failed: %s"),
+                       errmsg);
+        goto error;
+    }
+
+    /* verify the SSH host key */
+    if ((ret = virNetLibSSHCheckHostKey(sess)) != 0)
+        goto error;
+
+    /* authenticate */
+    if ((ret = virNetLibSSHAuthenticate(sess)) != 0)
+        goto error;
+
+    /* open channel */
+    if ((ret = virNetLibSSHOpenChannel(sess)) != 0)
+        goto error;
+
+    /* all set */
+    /* switch to nonblocking mode and return */
+    libssh2_session_set_blocking(sess->session, 0);
+    sess->state = VIR_NET_LIBSSH_STATE_HANDSHAKE_COMPLETE;
+
+    virMutexUnlock(&sess->lock);
+    return ret;
+
+error:
+    sess->state = VIR_NET_LIBSSH_STATE_ERROR;
+    virMutexUnlock(&sess->lock);
+    return ret;
+}
+
+/* do a read from a ssh channel, used instead of normal read on socket */
+ssize_t
+virNetLibSSHChannelRead(virNetLibSSHSessionPtr sess,
+                        char *buf,
+                        size_t len)
+{
+    ssize_t ret = -1;
+    ssize_t read_n = 0;
+
+    virMutexLock(&sess->lock);
+
+    if (sess->state != VIR_NET_LIBSSH_STATE_HANDSHAKE_COMPLETE) {
+        if (sess->state == VIR_NET_LIBSSH_STATE_ERROR_REMOTE)
+            virReportError(VIR_ERR_LIBSSH_ERROR,
+                           _("Remote program terminated with non-zero code: %d"),
+                           sess->channelCommandReturnValue);
+        else
+            virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                           _("Tried to write socket in error state"));
+
+        virMutexUnlock(&sess->lock);
+        return -1;
+    }
+
+    if (sess->bufUsed > 0) {
+        /* copy the rest (or complete) internal buffer to the output buffer */
+        memcpy(buf,
+               sess->rbuf + sess->bufStart,
+               len > sess->bufUsed?sess->bufUsed:len);
+
+        if (len >= sess->bufUsed) {
+            read_n = sess->bufUsed;
+
+            sess->bufStart = 0;
+            sess->bufUsed = 0;
+        } else {
+            read_n = len;
+            sess->bufUsed -= len;
+            sess->bufStart += len;
+
+            goto success;
+        }
+    }
+
+    /* continue reading into the buffer supplied */
+    if (read_n < len) {
+        ret = libssh2_channel_read(sess->channel,
+                                   buf + read_n,
+                                   len - read_n);
+
+        if (ret == LIBSSH2_ERROR_EAGAIN)
+            goto success;
+
+        if (ret < 0)
+            goto error;
+
+        read_n += ret;
+    }
+
+    /* try to read something into the internal buffer */
+    if (sess->bufUsed == 0) {
+        ret = libssh2_channel_read(sess->channel,
+                                   sess->rbuf,
+                                   VIR_NET_LIBSSH_BUFFER_SIZE);
+
+        if (ret == LIBSSH2_ERROR_EAGAIN)
+            goto success;
+
+        if (ret < 0)
+            goto error;
+
+        sess->bufUsed = ret;
+        sess->bufStart = 0;
+    }
+
+    if (read_n == 0) {
+        /* get rid of data in stderr stream */
+        ret = libssh2_channel_read_stderr(sess->channel,
+                                          sess->rbuf,
+                                          VIR_NET_LIBSSH_BUFFER_SIZE - 1);
+        if (ret > 0) {
+            sess->rbuf[ret] = '\0';
+            VIR_DEBUG("flushing stderr, data='%s'",  sess->rbuf);
+        }
+    }
+
+    if (libssh2_channel_eof(sess->channel)) {
+        if (libssh2_channel_get_exit_status(sess->channel)) {
+            virReportError(VIR_ERR_LIBSSH_ERROR,
+                           _("Remote command terminated with non-zero code: %d"),
+                           libssh2_channel_get_exit_status(sess->channel));
+            sess->channelCommandReturnValue = libssh2_channel_get_exit_status(sess->channel);
+            sess->state = VIR_NET_LIBSSH_STATE_ERROR_REMOTE;
+            virMutexUnlock(&sess->lock);
+            return -1;
+        }
+
+        sess->state = VIR_NET_LIBSSH_STATE_CLOSED;
+        virMutexUnlock(&sess->lock);
+        return -1;
+    }
+
+success:
+    virMutexUnlock(&sess->lock);
+    return read_n;
+
+error:
+    sess->state = VIR_NET_LIBSSH_STATE_ERROR;
+    virMutexUnlock(&sess->lock);
+    return ret;
+}
+
+ssize_t
+virNetLibSSHChannelWrite(virNetLibSSHSessionPtr sess,
+                         const char *buf,
+                         size_t len)
+{
+    ssize_t ret;
+
+    virMutexLock(&sess->lock);
+
+    if (sess->state != VIR_NET_LIBSSH_STATE_HANDSHAKE_COMPLETE) {
+        if (sess->state == VIR_NET_LIBSSH_STATE_ERROR_REMOTE)
+            virReportError(VIR_ERR_LIBSSH_ERROR,
+                           _("Remote program terminated with non-zero code: %d"),
+                           sess->channelCommandReturnValue);
+        else
+            virReportError(VIR_ERR_LIBSSH_ERROR, "%s",
+                           _("Tried to write socket in error state"));
+        ret = -1;
+        goto cleanup;
+    }
+
+    if (libssh2_channel_eof(sess->channel)) {
+        if (libssh2_channel_get_exit_status(sess->channel)) {
+            virReportError(VIR_ERR_LIBSSH_ERROR,
+                           _("Remote program terminated with non-zero code: %d"),
+                           libssh2_channel_get_exit_status(sess->channel));
+            sess->state = VIR_NET_LIBSSH_STATE_ERROR_REMOTE;
+            sess->channelCommandReturnValue = libssh2_channel_get_exit_status(sess->channel);
+
+            ret = -1;
+            goto cleanup;
+        }
+
+        sess->state = VIR_NET_LIBSSH_STATE_CLOSED;
+        ret = -1;
+        goto cleanup;
+    }
+
+    ret = libssh2_channel_write(sess->channel, buf, len);
+    if (ret == LIBSSH2_ERROR_EAGAIN) {
+        ret = 0;
+        goto cleanup;
+    }
+
+    if (ret < 0) {
+        char *msg;
+        sess->state = VIR_NET_LIBSSH_STATE_ERROR;
+        libssh2_session_last_error(sess->session, &msg, NULL, 0);
+        virReportError(VIR_ERR_LIBSSH_ERROR,
+                       _("write failed: %s"), msg);
+    }
+
+cleanup:
+    virMutexUnlock(&sess->lock);
+    return ret;
+}
+
+bool virNetLibSSHHasCachedData(virNetLibSSHSessionPtr sess)
+{
+    bool ret;
+
+    if (!sess)
+        return false;
+
+    virMutexLock(&sess->lock);
+
+    ret = sess->bufUsed > 0;
+
+    virMutexUnlock(&sess->lock);
+    return ret;
+}
diff --git a/src/rpc/virnetlibsshcontext.h b/src/rpc/virnetlibsshcontext.h
new file mode 100644
index 0000000..1fe90ed
--- /dev/null
+++ b/src/rpc/virnetlibsshcontext.h
@@ -0,0 +1,83 @@
+/*
+ * virnetlibsshcontext.h: libssh transport provider
+ *
+ * Copyright (C) 2012 Red Hat, Inc.
+ *
+ * This 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.
+ *
+ * This 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 this library;  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * Author: Peter Krempa <pkrempa redhat com>
+ */
+#ifndef __VIR_NET_LIBSSH_CONTEXT_H__
+# define __VIR_NET_LIBSSH_CONTEXT_H__
+
+# include "internal.h"
+
+typedef struct _virNetLibSSHSession virNetLibSSHSession;
+typedef virNetLibSSHSession *virNetLibSSHSessionPtr;
+
+virNetLibSSHSessionPtr virNetLibSSHSessionNew(void);
+void virNetLibSSHSessionFree(virNetLibSSHSessionPtr sess);
+
+typedef enum {
+    VIR_NET_LIBSSH_HOSTKEY_VERIFY_NORMAL,
+    VIR_NET_LIBSSH_HOSTKEY_VERIFY_AUTO_ADD,
+    VIR_NET_LIBSSH_HOSTKEY_VERIFY_IGNORE
+} virNetLibSSHHostkeyVerify;
+
+int virNetLibSSHSessionSetChannelCommand(virNetLibSSHSessionPtr sess,
+                                         const char *command);
+
+void virNetLibSSHSessionAuthReset(virNetLibSSHSessionPtr sess);
+
+int virNetLibSSHSessionAuthSetCallback(virNetLibSSHSessionPtr sess,
+                                       virConnectAuthPtr auth);
+
+int virNetLibSSHSessionAuthAddPasswordAuth(virNetLibSSHSessionPtr sess,
+                                           const char *username,
+                                           const char *password);
+
+int virNetLibSSHSessionAuthAddAgentAuth(virNetLibSSHSessionPtr sess,
+                                        const char *username);
+
+int virNetLibSSHSessionAuthAddPrivKeyAuth(virNetLibSSHSessionPtr sess,
+                                          const char *username,
+                                          const char *keyfile,
+                                          const char *password);
+
+int virNetLibSSHSessionAuthAddKeyboardAuth(virNetLibSSHSessionPtr sess,
+                                           const char *username,
+                                           int tries);
+
+int virNetLibSSHSessionSetHostKeyVerification(virNetLibSSHSessionPtr sess,
+                                              const char *hostname,
+                                              int port,
+                                              const char *hostsfile,
+                                              bool readonly,
+                                              virNetLibSSHHostkeyVerify opt);
+
+int virNetLibSSHSessionConnect(virNetLibSSHSessionPtr sess,
+                               int sock);
+
+ssize_t virNetLibSSHChannelRead(virNetLibSSHSessionPtr sess,
+                                char *buf,
+                                size_t len);
+
+ssize_t virNetLibSSHChannelWrite(virNetLibSSHSessionPtr sess,
+                                 const char *buf,
+                                 size_t len);
+
+bool virNetLibSSHHasCachedData(virNetLibSSHSessionPtr sess);
+
+#endif /* __VIR_NET_LIBSSH_CONTEXT_H__ */
diff --git a/src/util/virterror.c b/src/util/virterror.c
index a40cfe0..586ac0f 100644
--- a/src/util/virterror.c
+++ b/src/util/virterror.c
@@ -112,7 +112,8 @@ VIR_ENUM_IMPL(virErrorDomain, VIR_ERR_DOMAIN_LAST,
               "URI Utils", /* 45 */
               "Authentication Utils",
               "DBus Utils",
-              "Parallels Cloud Server"
+              "Parallels Cloud Server",
+              "LibSSH2 transport"
     )


@@ -1185,6 +1186,11 @@ virErrorMsg(virErrorNumber error, const char *info)
             else
                 errmsg = _("block copy still active: %s");
             break;
+        case VIR_ERR_LIBSSH_ERROR:
+            if (info == NULL)
+                errmsg = _("LibSSH2 transport error");
+            else
+                errmsg = _("LibSSH2 transport error: %s");
     }
     return errmsg;
 }
-- 
1.7.8.6


[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]