keyboard-interactive auth for NSE via libssh2

nselib/libssh2-utility.lua

@@ -10,6 +10,7 @@
 
 local stdnse = require "stdnse"
 local table = require "table"
+local tableaux = require "tableaux"
 
 local libssh2 = stdnse.silent_require "libssh2"
 
@@ -81,7 +82,7 @@ function SSHConnection:run_remote (cmd, no_pty)
 end
 
 ---
--- Attempts to authenticate using provided credentials.
+-- Attempts to authenticate using password authentication.
 --
 -- @param username A username to authenticate as.
 -- @param password A password to authenticate as.
@@ -98,6 +99,66 @@ function SSHConnection:password_auth (username, password)
   end
 end
 
+local function kbd_get_cb(func)
+  return function(username, name, instruction, prompts)
+    local responses = {}
+    for i=1, #prompts do
+      stdnse.debug2("Auth for %s: '%s' '%s' '%s'",
+        username, name, instruction, prompts[i])
+      responses[i] = func(username, name, instruction, prompts[i])
+      stdnse.debug2("Response: %s", responses[i])
+    end
+    return responses
+  end
+end
+
+---
+-- Attempts to authenticate using keyboard-interactive authentication.
+--
+-- @param username A username to authenticate as.
+-- @param callback A callback function that takes 4 inputs (username, name,
+--                 instruction, prompt) and returns one string response.
+-- @return true on success or false on failure.
+function SSHConnection:interactive_auth (username, callback)
+  if not self.session then
+    return false
+  end
+  if libssh2.userauth_keyboard_interactive(self.session, username, kbd_get_cb(callback)) then
+    self.authenticated = true
+    return true
+  else
+    return false
+  end
+end
+
+---
+-- Attempts to authenticate using provided credentials.
+--
+-- Lists available userauth methods and attempts to authenticate with the given
+-- credentials. If password authentication is not available, it will use
+-- keyboard-interactive authentication, responding with <code>password</code>
+-- to any prompts.
+--
+-- @param username A username to authenticate as.
+-- @param password A password
+-- @return true on success or false on failure.
+-- @return the successful auth method, or all methods available. If nil, no methods were found.
+function SSHConnection:login (username, password)
+  local methods = self:list(username)
+  if not methods then
+    return false
+  end
+  if (tableaux.contains(methods, "password")
+      and self:password_auth(username, password)) then
+    return true, "password"
+  end
+  if (tableaux.contains(methods, "keyboard-interactive") and
+      self:interactive_auth(username, function() return password end)) then
+    return true, "keyboard-interactive"
+  end
+  return false, methods
+end
+
 ---
 -- Attempts to authenticate using provided private key file.
 --