try to read introspection_endpoint from discovery as fallback

see #255

Signed-off-by: Stefan Bodewig <[email protected]>

ChangeLog

@@ -2,6 +2,7 @@
 - added unauth_action='deny' to reject unauthenticated requests rather
   than start the authorization code grant flow; see #271; based on
   suggested change by @nmaniwa
+- read introspection_endpoint from discovery document when present; see #255
 
 05/01/2019
 - performance enhancement by caching the result of ngx.req.get_headers

README.md

@@ -490,7 +490,14 @@ http {
       access_by_lua '
 
           local opts = {
+             -- sets the URI of the introspection endpoint
              introspection_endpoint="https://localhost:9031/oauth2/introspect",
+
+             -- alternatively if your OAuth2 Provider provides a discovery document that contains the
+             -- introspection_endpoint claim you can leave the introspection_endpoint option
+             -- unset and instead use
+             -- discovery = "https://my-oauth2-provider/.well-known/oauth-authorization-server",
+
              client_id="admin",
              client_secret="demo-password",
              ssl_verify = "no",

lib/resty/openidc.lua

@@ -414,6 +414,10 @@ function openidc.call_token_endpoint(opts, endpoint, body, auth, endpoint_name,
   local ignore_body_on_success = ignore_body_on_success or false
 
   local ep_name = endpoint_name or 'token'
+  if not endpoint then
+    return nil, 'no endpoint URI for ' .. ep_name
+  end
+
   local headers = {
     ["Content-Type"] = "application/x-www-form-urlencoded"
   }
@@ -1603,7 +1607,18 @@ function openidc.introspect(opts)
   end
 
   -- call the introspection endpoint
-  json, err = openidc.call_token_endpoint(opts, opts.introspection_endpoint, body, opts.introspection_endpoint_auth_method, "introspection")
+  local introspection_endpoint = opts.introspection_endpoint
+  if not introspection_endpoint then
+    err = openidc_ensure_discovered_data(opts)
+    if err then
+      return nil, "opts.introspection_endpoint not said and " .. err
+    end
+    local endpoint = opts.discovery and opts.discovery.introspection_endpoint
+    if endpoint then
+      introspection_endpoint = endpoint
+    end
+  end
+  json, err = openidc.call_token_endpoint(opts, introspection_endpoint, body, opts.introspection_endpoint_auth_method, "introspection")
 
 
   if not json then

tests/spec/introspection_spec.lua

@@ -526,3 +526,41 @@ describe("when a request_decorator has been specified when calling the token end
   end)
 end)
 
+describe("when introspection endpoint hasn't been specified", function()
+  test_support.start_server({
+    remove_introspection_config_keys = { 'introspection_endpoint' }
+  })
+  teardown(test_support.stop_server)
+  local jwt = test_support.trim(http.request("http://127.0.0.1/jwt"))
+  local _, status = http.request({
+    url = "http://127.0.0.1/introspect",
+    headers = { authorization = "Bearer " .. jwt }
+  })
+  it("the response is invalid", function()
+    assert.are.equals(401, status)
+  end)
+  it("an error has been logged", function()
+    assert.error_log_contains("Introspection error: no endpoint URI for introspection")
+  end)
+end)
+
+describe("when introspection endpoint hasn't been specified but discovery doc provides introspection_endpoint claim", function()
+  test_support.start_server({
+    remove_introspection_config_keys = { 'introspection_endpoint' },
+    introspection_opts = {
+      discovery = {
+        introspection_endpoint = "http://127.0.0.1/introspection"
+      }
+    },
+  })
+  teardown(test_support.stop_server)
+  local jwt = test_support.trim(http.request("http://127.0.0.1/jwt"))
+  local _, status = http.request({
+    url = "http://127.0.0.1/introspect",
+    headers = { authorization = "Bearer " .. jwt }
+  })
+  it("the response is valid", function()
+     assert.are.equals(200, status)
+  end)
+end)
+

tests/spec/test_support.lua

@@ -450,6 +450,9 @@ local function write_config(out, custom_config)
   for _, k in ipairs(custom_config["remove_oidc_config_keys"] or {}) do
     oidc_config[k] = nil
   end
+  for _, k in ipairs(custom_config["remove_introspection_config_keys"] or {}) do
+    introspection_opts[k] = nil
+  end
   local config = DEFAULT_CONFIG_TEMPLATE
     :gsub("OIDC_CONFIG", serpent.block(oidc_config, {comment = false }))
     :gsub("TOKEN_HEADER", serpent.block(token_header, {comment = false }))
@@ -501,6 +504,8 @@ end
 --   the introspection endpoint
 -- - remove_introspection_claims is an array of claims to remove from the introspection response
 -- - introspection_opts is a table containing options that are accepted by oidc.introspect
+-- - remove_introspection_config_keys is an array of claims to remove from the introspection
+--   configuration
 -- - token_response_expires_in value for the expires_in claim of the token response
 -- - token_response_contains_refresh_token whether to include a
 --   refresh token with the token response (a boolean in quotes, i.e. "true" or "false")