Login via OpenID-2.0 (#618)

vendor/github.com/yohcop/openid-go/discover.go

@@ -0,0 +1,57 @@
+package openid
+
+// 7.3.1.  Discovered Information
+// Upon successful completion of discovery, the Relying Party will
+// have one or more sets of the following information (see the
+// Terminology section for definitions). If more than one set of the
+// following information has been discovered, the precedence rules
+// defined in [XRI_Resolution_2.0] are to be applied.
+//   - OP Endpoint URL
+//   - Protocol Version
+// If the end user did not enter an OP Identifier, the following
+// information will also be present:
+//   - Claimed Identifier
+//   - OP-Local Identifier
+// If the end user entered an OP Identifier, there is no Claimed
+// Identifier. For the purposes of making OpenID Authentication
+// requests, the value
+// "http://specs.openid.net/auth/2.0/identifier_select" MUST be
+// used as both the Claimed Identifier and the OP-Local Identifier
+// when an OP Identifier is entered.
+func Discover(id string) (opEndpoint, opLocalID, claimedID string, err error) {
+	return defaultInstance.Discover(id)
+}
+
+func (oid *OpenID) Discover(id string) (opEndpoint, opLocalID, claimedID string, err error) {
+	// From OpenID specs, 7.2: Normalization
+	if id, err = Normalize(id); err != nil {
+		return
+	}
+
+	// From OpenID specs, 7.3: Discovery.
+
+	// If the identifier is an XRI, [XRI_Resolution_2.0] will yield an
+	// XRDS document that contains the necessary information. It
+	// should also be noted that Relying Parties can take advantage of
+	// XRI Proxy Resolvers, such as the one provided by XDI.org at
+	// http://www.xri.net. This will remove the need for the RPs to
+	// perform XRI Resolution locally.
+
+	// XRI not supported.
+
+	// If it is a URL, the Yadis protocol [Yadis] SHALL be first
+	// attempted. If it succeeds, the result is again an XRDS
+	// document.
+	if opEndpoint, opLocalID, err = yadisDiscovery(id, oid.urlGetter); err != nil {
+		// If the Yadis protocol fails and no valid XRDS document is
+		// retrieved, or no Service Elements are found in the XRDS
+		// document, the URL is retrieved and HTML-Based discovery SHALL be
+		// attempted.
+		opEndpoint, opLocalID, claimedID, err = htmlDiscovery(id, oid.urlGetter)
+	}
+
+	if err != nil {
+		return "", "", "", err
+	}
+	return
+}