Fixing SSH Tunnel logic for changes in the SSH library

At version 0.10.6, the libssh library introduced logic that could lead
to an unhandled exception in the shell when setting an invalid hostname.
Since SSH produces an exception with no code or error message, this
patch adds the proper handling and a custom error message.

Change-Id: If60f2d5a78866d10a2393d816168f48998b42acb

Author: rennox

mysqlshdk/libs/ssh/ssh_session.cc

@@ -564,11 +564,16 @@ void Ssh_session::authenticate_user(const ssh::Ssh_connection_options &config) {
   }
 
   if (ret_val != Ssh_auth_return::AUTH_SUCCESS) {
-    if (ret_val == Ssh_auth_return::AUTH_DENIED)
+    if (ret_val == Ssh_auth_return::AUTH_DENIED) {
       throw Ssh_auth_exception("Access denied");
-    else if (ret_val != Ssh_auth_return::AUTH_NONE)
+    } else if (ret_val != Ssh_auth_return::AUTH_NONE) {
       throw std::runtime_error(
           "Unable to authenticate, all known authentication methods failed.");
+    } else {
+      throw std::runtime_error(
+          "Unable to authenticate, no compatible authentication methods "
+          "found.");
+    }
   }
 }
 

mysqlshdk/libs/ssh/ssh_session_options.cc

@@ -60,7 +60,20 @@ Ssh_session_options::Ssh_session_options(const std::string &config,
     m_no_host = true;
     return;
   }
-  m_session->setOption(SSH_OPTIONS_HOST, host.c_str());
+  try {
+    m_session->setOption(SSH_OPTIONS_HOST, host.c_str());
+  } catch (::ssh::SshException &exc) {
+    auto error = exc.getError();
+    if (error.empty()) {
+      error = shcore::str_format(
+          "SSH: Error setting remote host in ssh session: host '%s' is not "
+          "valid",
+          host.c_str());
+    }
+
+    throw std::invalid_argument(error);
+  }
+
   try {
     // On empty we pass nullptr to trigger loading the default configuration
     // files

unittest/scripts/auto/py_shell/scripts/shell_ssh_errors_norecord.py

@@ -127,7 +127,11 @@
 
 #@<> Tunnel Creation Errors - Invalid SSH host
 testutil.call_mysqlsh(["--ssh", "ssh_user@invalid_host", MYSQL_OVER_SSH_URI])
-EXPECT_STDOUT_CONTAINS("Cannot open SSH Tunnel: Failed to resolve hostname invalid_host")
+EXPECT_STDOUT_CONTAINS("SSH: Error setting remote host in ssh session: host 'invalid_host' is not valid")
+WIPE_STDOUT()
+
+testutil.call_mysqlsh(["--ssh", "ssh_user@Whatever", MYSQL_OVER_SSH_URI])
+EXPECT_STDOUT_CONTAINS("Cannot open SSH Tunnel: Failed to resolve hostname Whatever")
 WIPE_STDOUT()
 
 #@<> Tunnel Creation Errors - Invalid User

unittest/scripts/auto/py_shell/scripts/shell_ssh_norecord.py

@@ -362,7 +362,7 @@ def check_connection(obj, connection_data):
 conns = [{'uri':MYSQL_OVER_SSH_URI, 'ssh':'ssh_user@invalid_host', 'ssh-password':'ssh_pwd'},
          {'uri':MYSQL_OVER_SSH_URI, 'ssh':'invalid_user@invalid_host', 'ssh-password':'ssh_pwd'}]
 for c in conns:
-    EXPECT_THROWS(lambda: shell.connect(c), "Cannot open SSH Tunnel: Failed to resolve hostname invalid_host")
+    EXPECT_THROWS(lambda: shell.connect(c), "SSH: Error setting remote host in ssh session: host 'invalid_host' is not valid")
 
 EXPECT_THROWS(lambda: shell.connect({'uri':MYSQL_OVER_SSH_URI, 'ssh':'', 'ssh-password':'ssh_pwd'}), "Invalid URI: Expected token at position 0 but no tokens left.")
 EXPECT_THROWS(lambda: shell.connect({'uri':MYSQL_OVER_SSH_URI, 'ssh':'ssh_user@host name', 'ssh-password':'ssh_pwd'}), "Invalid URI: Illegal space found at position 13")