Login via OpenID-2.0 (#618)

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

@@ -0,0 +1,83 @@
+package openid
+
+import (
+	"encoding/xml"
+	"errors"
+	"strings"
+)
+
+// TODO: As per 11.2 in openid 2 specs, a service may have multiple
+//       URIs. We don't care for discovery really, but we do care for
+//       verification though.
+type XrdsIdentifier struct {
+	Type     []string `xml:"Type"`
+	URI      string   `xml:"URI"`
+	LocalID  string   `xml:"LocalID"`
+	Priority int      `xml:"priority,attr"`
+}
+
+type Xrd struct {
+	Service []*XrdsIdentifier `xml:"Service"`
+}
+
+type XrdsDocument struct {
+	XMLName xml.Name `xml:"XRDS"`
+	Xrd     *Xrd     `xml:"XRD"`
+}
+
+func parseXrds(input []byte) (opEndpoint, opLocalID string, err error) {
+	xrdsDoc := &XrdsDocument{}
+	err = xml.Unmarshal(input, xrdsDoc)
+	if err != nil {
+		return
+	}
+
+	if xrdsDoc.Xrd == nil {
+		return "", "", errors.New("XRDS document missing XRD tag")
+	}
+
+	// 7.3.2.2.  Extracting Authentication Data
+	// Once the Relying Party has obtained an XRDS document, it
+	// MUST first search the document (following the rules
+	// described in [XRI_Resolution_2.0]) for an OP Identifier
+	// Element. If none is found, the RP will search for a Claimed
+	// Identifier Element.
+	for _, service := range xrdsDoc.Xrd.Service {
+		// 7.3.2.1.1.  OP Identifier Element
+		// An OP Identifier Element is an <xrd:Service> element with the
+		// following information:
+		// An <xrd:Type> tag whose text content is
+		//     "http://specs.openid.net/auth/2.0/server".
+		// An <xrd:URI> tag whose text content is the OP Endpoint URL
+		if service.hasType("http://specs.openid.net/auth/2.0/server") {
+			opEndpoint = strings.TrimSpace(service.URI)
+			return
+		}
+	}
+	for _, service := range xrdsDoc.Xrd.Service {
+		// 7.3.2.1.2.  Claimed Identifier Element
+		// A Claimed Identifier Element is an <xrd:Service> element
+		// with the following information:
+		// An <xrd:Type> tag whose text content is
+		//     "http://specs.openid.net/auth/2.0/signon".
+		// An <xrd:URI> tag whose text content is the OP Endpoint
+		//     URL.
+		// An <xrd:LocalID> tag (optional) whose text content is the
+		//     OP-Local Identifier.
+		if service.hasType("http://specs.openid.net/auth/2.0/signon") {
+			opEndpoint = strings.TrimSpace(service.URI)
+			opLocalID = strings.TrimSpace(service.LocalID)
+			return
+		}
+	}
+	return "", "", errors.New("Could not find a compatible service")
+}
+
+func (xrdsi *XrdsIdentifier) hasType(tpe string) bool {
+	for _, t := range xrdsi.Type {
+		if t == tpe {
+			return true
+		}
+	}
+	return false
+}