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kumo.on('http_server_validate_auth_basic', function(USER, PASSWORD))

Called by the HTTP listener to validate HTTP Basic authentication credentials provided by the client.

At the time of writing KumoMTA doesn't provide a general authentication solution, but through the use of this callback, you have some flexibility.

The event handler receives the username and password provided by the client. Note that the password may be empty or missing if the client provided only a user name.

The HTTP server expects the event handler to return a bool value; if it returns true then it considers the credentials to be valid and will allow the client to access the endpoint. If it returns false then it will consider the credentials to be invalid and return a authorization error. Other return values, or raising an error, will return an error status to the client.

This example shows how to implement a very simple inline password database using a lua table:

-- Use this to lookup and confirm a user/password credential
-- used with the http endpoint
kumo.on('http_server_validate_auth_basic', function(user, password)
  local password_database = {
    ['scott'] = 'tiger',
  if password == '' then
    return false
  return password_database[user] == password

Reasoning about the authorized identity

When using auth to grant access to the HTTP injection API, the authorization identity will be made available in the generated message by setting the http_auth meta key. It can have one of the following values:

  • When HTTP Basic auth is used (and validated via the http_server_validate_auth_basic event), it will be set to the provided username
  • When no HTTP auth is used, access is granted based on the trusted_hosts. In this case, http_auth will be set to the peer address that matched the trusted_hosts

If you wish to enforce or restrict some capability based on identity, you might use logic along the lines of:

kumo.on('http_message_generated', function(msg)
  local auth = msg:get_meta 'http_auth'
  if auth ~= '' then
    error 'only is allowed to inject'

Last update: 2023-09-12
Created: 2023-02-26