From d647eed22ac5913882f60b33330b60aee6ac9238 Mon Sep 17 00:00:00 2001
From: Jack Merrill <8814123+jackmerrill@users.noreply.github.com>
Date: Thu, 26 Sep 2024 01:06:36 -0400
Subject: [PATCH] feat: add OIDC WebFinger support (#3245)

* feat: add WebFinger support

* lint: used gofumpt

* oidc: ensure webfinger rel is checked
---
 authz/authz.go                |  1 +
 controllers/oidc_discovery.go | 34 ++++++++++++++++++++++-
 object/oidc_discovery.go      | 52 +++++++++++++++++++++++++++++++++++
 routers/router.go             |  1 +
 4 files changed, 87 insertions(+), 1 deletion(-)

diff --git a/authz/authz.go b/authz/authz.go
index aae7ed38..81389723 100644
--- a/authz/authz.go
+++ b/authz/authz.go
@@ -77,6 +77,7 @@ p, *, *, POST, /api/verify-code, *, *
 p, *, *, POST, /api/reset-email-or-phone, *, *
 p, *, *, POST, /api/upload-resource, *, *
 p, *, *, GET, /.well-known/openid-configuration, *, *
+p, *, *, GET, /.well-known/webfinger, *, *
 p, *, *, *, /.well-known/jwks, *, *
 p, *, *, GET, /api/get-saml-login, *, *
 p, *, *, POST, /api/acs, *, *
diff --git a/controllers/oidc_discovery.go b/controllers/oidc_discovery.go
index 8986c80f..9598e1a3 100644
--- a/controllers/oidc_discovery.go
+++ b/controllers/oidc_discovery.go
@@ -14,7 +14,11 @@
 
 package controllers
 
-import "github.com/casdoor/casdoor/object"
+import (
+	"strings"
+
+	"github.com/casdoor/casdoor/object"
+)
 
 // GetOidcDiscovery
 // @Title GetOidcDiscovery
@@ -42,3 +46,31 @@ func (c *RootController) GetJwks() {
 	c.Data["json"] = jwks
 	c.ServeJSON()
 }
+
+// GetWebFinger
+// @Title GetWebFinger
+// @Tag OIDC API
+// @Param resource query string true "resource"
+// @Success 200 {object} object.WebFinger
+// @router /.well-known/webfinger [get]
+func (c *RootController) GetWebFinger() {
+	resource := c.Input().Get("resource")
+	rels := []string{}
+	host := c.Ctx.Request.Host
+
+	for key, value := range c.Input() {
+		if strings.HasPrefix(key, "rel") {
+			rels = append(rels, value...)
+		}
+	}
+
+	webfinger, err := object.GetWebFinger(resource, rels, host)
+	if err != nil {
+		c.ResponseError(err.Error())
+		return
+	}
+
+	c.Data["json"] = webfinger
+	c.Ctx.Output.ContentType("application/jrd+json")
+	c.ServeJSON()
+}
diff --git a/object/oidc_discovery.go b/object/oidc_discovery.go
index f6671f57..eb6695c9 100644
--- a/object/oidc_discovery.go
+++ b/object/oidc_discovery.go
@@ -44,6 +44,18 @@ type OidcDiscovery struct {
 	EndSessionEndpoint                     string   `json:"end_session_endpoint"`
 }
 
+type WebFinger struct {
+	Subject    string             `json:"subject"`
+	Links      []WebFingerLink    `json:"links"`
+	Aliases    *[]string          `json:"aliases,omitempty"`
+	Properties *map[string]string `json:"properties,omitempty"`
+}
+
+type WebFingerLink struct {
+	Rel  string `json:"rel"`
+	Href string `json:"href"`
+}
+
 func isIpAddress(host string) bool {
 	// Attempt to split the host and port, ignoring the error
 	hostWithoutPort, _, err := net.SplitHostPort(host)
@@ -160,3 +172,43 @@ func GetJsonWebKeySet() (jose.JSONWebKeySet, error) {
 
 	return jwks, nil
 }
+
+func GetWebFinger(resource string, rels []string, host string) (WebFinger, error) {
+	wf := WebFinger{}
+
+	resourceSplit := strings.Split(resource, ":")
+
+	if len(resourceSplit) != 2 {
+		return wf, fmt.Errorf("invalid resource")
+	}
+
+	resourceType := resourceSplit[0]
+	resourceValue := resourceSplit[1]
+
+	oidcDiscovery := GetOidcDiscovery(host)
+
+	switch resourceType {
+	case "acct":
+		user, err := GetUserByEmailOnly(resourceValue)
+		if err != nil {
+			return wf, err
+		}
+
+		if user == nil {
+			return wf, fmt.Errorf("user not found")
+		}
+
+		wf.Subject = resource
+
+		for _, rel := range rels {
+			if rel == "http://openid.net/specs/connect/1.0/issuer" {
+				wf.Links = append(wf.Links, WebFingerLink{
+					Rel:  "http://openid.net/specs/connect/1.0/issuer",
+					Href: oidcDiscovery.Issuer,
+				})
+			}
+		}
+	}
+
+	return wf, nil
+}
diff --git a/routers/router.go b/routers/router.go
index 09f18c80..37fba391 100644
--- a/routers/router.go
+++ b/routers/router.go
@@ -290,6 +290,7 @@ func initAPI() {
 
 	beego.Router("/.well-known/openid-configuration", &controllers.RootController{}, "GET:GetOidcDiscovery")
 	beego.Router("/.well-known/jwks", &controllers.RootController{}, "*:GetJwks")
+	beego.Router("/.well-known/webfinger", &controllers.RootController{}, "GET:GetWebFinger")
 
 	beego.Router("/cas/:organization/:application/serviceValidate", &controllers.RootController{}, "GET:CasServiceValidate")
 	beego.Router("/cas/:organization/:application/proxyValidate", &controllers.RootController{}, "GET:CasProxyValidate")