vestibule_indieauth/discovery

IndieAuth endpoint discovery.

Implements the discovery algorithm from IndieAuth spec Section 4.1:

1. Fetch the user’s profile URL
2. Look for rel="indieauth-metadata" — if found, fetch metadata JSON
3. Fall back to rel="authorization_endpoint" and rel="token_endpoint"
4. Check HTTP Link headers first, then HTML <link> tags

Types

DiscoveredEndpoints

Endpoints discovered from a user’s IndieAuth server.

pub type DiscoveredEndpoints {
  DiscoveredEndpoints(
    authorization_endpoint: String,
    token_endpoint: String,
    issuer: option.Option(String),
    userinfo_endpoint: option.Option(String)
  )
}

ProfileDiscovery

Result of parsing a profile-page discovery response.

A profile can either contain the authorization and token endpoint links directly, or point to a metadata document that requires one more request.

pub type ProfileDiscovery {
  EndpointsDiscovered(DiscoveredEndpoints)
  MetadataRequired(url: String)
}

Functions

build_metadata_request

Build an IndieAuth metadata request without sending it.

The returned request is opaque and must be sent with provider_support.send_public.

pub fn build_metadata_request(String) -> Result(provider_support.SecureRequest, error.AuthError(a))

build_profile_request

Build the request used to discover endpoints from a profile page.

The profile URL must be public HTTPS. The returned request is opaque and can only be sent with provider_support.send_public, so DNS validation and address pinning cannot be accidentally bypassed.

pub fn build_profile_request(String) -> Result(provider_support.SecureRequest, error.AuthError(a))

discover_endpoints

Discover IndieAuth endpoints from a user’s profile URL.

Fetches the URL and discovers endpoints using the three-tier fallback:

1. IndieAuth server metadata (rel="indieauth-metadata")
2. Direct link relations (rel="authorization_endpoint", rel="token_endpoint")
3. HTTP Link headers take precedence over HTML <link> tags

pub fn discover_endpoints(String) -> Result(DiscoveredEndpoints, error.AuthError(a))

find_html_link_relation

Find an HTML <link> element with the given rel attribute.

Uses presentable_soup for robust HTML parsing. Exported for testing.

pub fn find_html_link_relation(
  String,
  String
) -> option.Option(String)

find_link_header_relation

Parse HTTP Link headers to find a URL with the given rel value.

Handles the format: <URL>; rel="value" or <URL>; rel=value Exported for testing.

pub fn find_link_header_relation(
  List(#(String, String)),
  String
) -> option.Option(String)

parse_metadata

Parse IndieAuth server metadata JSON. Exported for testing.

pub fn parse_metadata(String) -> Result(DiscoveredEndpoints, error.AuthError(a))

parse_metadata_response

Parse an IndieAuth metadata HTTP response without performing I/O.

pub fn parse_metadata_response(
  String,
  response.Response(String)
) -> Result(DiscoveredEndpoints, error.AuthError(a))

parse_profile_response

Parse a profile-page discovery HTTP response without performing I/O.

pub fn parse_profile_response(
  String,
  response.Response(String)
) -> Result(ProfileDiscovery, error.AuthError(a))

validate_endpoints

Require every discovered endpoint to be a structurally safe HTTPS URL.

Discovered endpoints are chosen by whoever controls the profile URL, so without this check a login attempt could point the server’s token or userinfo requests at loopback, private, or cloud-metadata addresses (SSRF). Literal non-public addresses are rejected here. Immediately before each server-side request, provider_support.send_public additionally resolves every DNS answer, rejects mixed/non-public results, and pins the validated address to the connection.

pub fn validate_endpoints(DiscoveredEndpoints) -> Result(DiscoveredEndpoints, error.AuthError(a))