Add an addon for password-based authentication against Keycloak.

keycloakpassword/README.md

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+Keycloak Password Auth
+======================
+
+Allows for password-based authentication against a Keycloak backend. (Should in
+theory work with any OpenID Connect provider with "direct grant" enabled, but
+it's only been tested against Keycloak.)
+
+Setting up Keycloak for use with this addon is detailed [in this RedHat
+blog entry](https://developers.redhat.com/blog/2020/01/29/api-login-and-jwt-token-generation-using-keycloak#set_up_a_client).

keycloakpassword/keycloakpassword.php

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+<?php
+/**
+ * Name: Keycloak Password Auth
+ * Description: Allow password-based authentication via the user's Keycloak credentials.
+ * Version: 1.0
+ * Author: Ryan <https://verya.pe/profile/ryan>
+ */
+
+use Friendica\App;
+use Friendica\Core\Hook;
+use Friendica\Core\Logger;
+use Friendica\Core\Renderer;
+use Friendica\Database\DBA;
+use Friendica\DI;
+use Friendica\Model\User;
+
+function keycloakpassword_install()
+{
+	Hook::register('authenticate', __FILE__, 'keycloakpassword_authenticate');
+}
+
+function keycloakpassword_request($client_id, $secret, $url, $params = [])
+{
+	$ch = curl_init();
+	curl_setopt($ch, CURLOPT_URL, $url);
+	curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
+	curl_setopt($ch, CURLOPT_POST, 1);
+	curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query([
+		'client_id' => $client_id,
+		'grant_type' => 'password',
+		'client_secret' => $secret,
+		'scope' => 'openid',
+	] + $params));
+
+	$headers = array();
+	$headers[] = 'Content-Type: application/x-www-form-urlencoded';
+	curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
+	$res = curl_exec($ch);
+
+	if (curl_errno($ch)) {
+		Logger::error(curl_error($ch));
+	}
+	curl_close($ch);
+
+	return $res;
+}
+
+function keycloakpassword_authenticate($a, &$b)
+{
+	if (empty($b['password'])) {
+		return;
+	}
+
+	$client_id = DI::config()->get('keycloakpassword', 'client_id', null);
+	$endpoint = DI::config()->get('keycloakpassword', 'endpoint', null);
+	$secret = DI::config()->get('keycloakpassword', 'secret', null);
+
+	if (!$client_id || !$endpoint || !$secret) {
+		return;
+	}
+
+	$condition = [
+		'nickname' => $b['username'],
+		'blocked' => false,
+		'account_expired' => false,
+		'account_removed' => false
+	];
+
+	try {
+		$user = DBA::selectFirst('user', ['uid'], $condition);
+	} catch (Exception $e) {
+		return;
+	}
+
+	$json = keycloakpassword_request(
+		$client_id,
+		$secret,
+		$endpoint . '/token',
+		[
+			'username' => $b['username'],
+			'password' => $b['password']
+		]
+	);
+
+	$res = json_decode($json, true);
+	if (array_key_exists('access_token', $res) && !array_key_exists('error', $res)) {
+		$b['user_record'] = User::getById($user['uid']);
+		$b['authenticated'] = 1;
+
+		// Invalidate the Keycloak session we just created, as we have no use for it.
+		keycloakpassword_request(
+			$client_id,
+			$secret,
+			$endpoint . '/logout',
+			[ 'refresh_token' => res['refresh_token'] ]
+		);
+	}
+}
+
+function keycloakpassword_admin_input($key, $label, $description)
+{
+	return [
+		'$' . $key => [
+			$key,
+			$label,
+			DI::config()->get('keycloakpassword', $key),
+			$description,
+			true, // all the fields are required
+		]
+	];
+}
+
+function keycloakpassword_addon_admin(&$a, &$o)
+{
+	$form =
+		keycloakpassword_admin_input(
+			'client_id',
+			DI::l10n()->t('Client ID'),
+			DI::l10n()->t('The name of the OpenID Connect client you created for this addon in Keycloak.'),
+		) +
+		keycloakpassword_admin_input(
+			'secret',
+			DI::l10n()->t('Client secret'),
+			DI::l10n()->t('The secret assigned to the OpenID Connect client you created for this addon in Keycloak.'),
+		) +
+		keycloakpassword_admin_input(
+			'endpoint',
+			DI::l10n()->t('OpenID Connect endpoint'),
+			DI::l10n()->t(
+				'URL to the Keycloak endpoint for your client. '
+				. '(E.g., https://example.com/auth/realms/some-realm/protocol/openid-connect)'
+			),
+		) +
+		[
+			'$msg' => DI::session()->get('keycloakpassword-msg', false),
+			'$submit'  => DI::l10n()->t('Save Settings'),
+		];
+
+	$t = Renderer::getMarkupTemplate('admin.tpl', 'addon/keycloakpassword/');
+	$o = Renderer::replaceMacros($t, $form);
+}
+
+function keycloakpassword_addon_admin_post(&$a)
+{
+	if (!local_user()) {
+		return;
+	}
+
+	$set = function ($key) {
+		$val = (!empty($_POST[$key]) ? trim($_POST[$key]) : '');
+		DI::config()->set('keycloakpassword', $key, $val);
+	};
+	$set('client_id');
+	$set('secret');
+	$set('endpoint');
+}

keycloakpassword/templates/admin.tpl

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+{{include file="field_input.tpl" field=$client_id}}
+{{include file="field_input.tpl" field=$secret}}
+{{include file="field_input.tpl" field=$endpoint}}
+<div class="submit"><input type="submit" name="page_site" value="{{$submit}}" /></div>