Repository: coreos/dex (go)
Issue: Registration handler doesn't take full issuer URL into account
Here is the problem in handleAuthFunc() function:

```
if register {
	_, ok := idpc.(*connector.LocalConnector)
	if ok {
		q := url.Values{}
		q.Set("code", key)
		ru := httpPathRegister + "?" + q.Encode()
		w.Header().Set("Location", ru)
		w.WriteHeader(http.StatusFound)
		return
	}
}
```

It always redirects to httpPathRegister ("/register") w/o using issuerURL. So it's impossible to register a new user if dex is listening on a non-root path.
Pull request description: server: fix registration redirect for non-root URLs
Closes #553

cc @sym3tri @chancez 

Patch:
diff --git a/server/http.go b/server/http.go
index 007a9d4e..773246ac 100644
--- a/server/http.go
+++ b/server/http.go
@@ -7,6 +7,7 @@ import (
 	"io"
 	"net/http"
 	"net/url"
+	"path"
 	"strings"
 	"time"
 
@@ -266,7 +267,7 @@ func renderLoginPage(w http.ResponseWriter, r *http.Request, srv OIDCServer, idp
 	execTemplate(w, tpl, td)
 }
 
-func handleAuthFunc(srv OIDCServer, idpcs []connector.Connector, tpl *template.Template, registrationEnabled bool) http.HandlerFunc {
+func handleAuthFunc(srv OIDCServer, baseURL url.URL, idpcs []connector.Connector, tpl *template.Template, registrationEnabled bool) http.HandlerFunc {
 	idx := makeConnectorMap(idpcs)
 	return func(w http.ResponseWriter, r *http.Request) {
 		if r.Method != "GET" {
@@ -358,7 +359,7 @@ func handleAuthFunc(srv OIDCServer, idpcs []connector.Connector, tpl *template.T
 			if ok {
 				q := url.Values{}
 				q.Set("code", key)
-				ru := httpPathRegister + "?" + q.Encode()
+				ru := path.Join(baseURL.Path, httpPathRegister) + "?" + q.Encode()
 				w.Header().Set("Location", ru)
 				w.WriteHeader(http.StatusFound)
 				return
diff --git a/server/server.go b/server/server.go
index 120015d1..6ec37535 100644
--- a/server/server.go
+++ b/server/server.go
@@ -238,7 +238,7 @@ func (s *Server) HTTPHandler() http.Handler {
 	}
 
 	handleFunc(httpPathDiscovery, handleDiscoveryFunc(s.ProviderConfig()))
-	handleFunc(httpPathAuth, handleAuthFunc(s, s.Connectors, s.LoginTemplate, s.EnableRegistration))
+	handleFunc(httpPathAuth, handleAuthFunc(s, s.IssuerURL, s.Connectors, s.LoginTemplate, s.EnableRegistration))
 	handleFunc(httpPathOOB, handleOOBFunc(s, s.OOBTemplate))
 	handleFunc(httpPathToken, handleTokenFunc(s))
 	handleFunc(httpPathKeys, handleKeysFunc(s.KeyManager, clock))


Test patch:
diff --git a/server/cross_client_test.go b/server/cross_client_test.go
index 22d5b252..00099622 100644
--- a/server/cross_client_test.go
+++ b/server/cross_client_test.go
@@ -180,7 +180,7 @@ func TestHandleAuthCrossClient(t *testing.T) {
 	}
 
 	for i, tt := range tests {
-		hdlr := handleAuthFunc(f.srv, idpcs, nil, true)
+		hdlr := handleAuthFunc(f.srv, url.URL{}, idpcs, nil, true)
 		w := httptest.NewRecorder()
 
 		query := url.Values{
diff --git a/server/http_test.go b/server/http_test.go
index 28f0897a..fc5b2acc 100644
--- a/server/http_test.go
+++ b/server/http_test.go
@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"html/template"
 	"math/big"
 	"net/http"
 	"net/http/httptest"
@@ -54,7 +55,7 @@ func (c *fakeConnector) TrustedEmailProvider() bool {
 
 func TestHandleAuthFuncMethodNotAllowed(t *testing.T) {
 	for _, m := range []string{"POST", "PUT", "DELETE"} {
-		hdlr := handleAuthFunc(nil, nil, nil, true)
+		hdlr := handleAuthFunc(nil, url.URL{}, nil, nil, true)
 		req, err := http.NewRequest(m, "http://example.com", nil)
 		if err != nil {
 			t.Errorf("case %s: unable to create HTTP request: %v", m, err)
@@ -72,13 +73,28 @@ func TestHandleAuthFuncMethodNotAllowed(t *testing.T) {
 	}
 }
 
+func newLocalConnector(t *testing.T, id string) connector.Connector {
+	config := connector.LocalConnectorConfig{ID: id}
+	tmpl, err := template.New(connector.LoginPageTemplateName).Parse("")
+	if err != nil {
+		t.Fatalf("creating login template: %v", err)
+	}
+	conn, err := config.Connector(url.URL{}, nil, tmpl)
+	if err != nil {
+		t.Fatalf("creating connector: %v", err)
+	}
+	return conn
+}
+
 func TestHandleAuthFuncResponsesSingleRedirectURL(t *testing.T) {
 	idpcs := []connector.Connector{
 		&fakeConnector{loginURL: "http://fake.example.com"},
+		newLocalConnector(t, "local"),
 	}
 
 	tests := []struct {
 		query        url.Values
+		baseURL      url.URL
 		wantCode     int
 		wantLocation string
 	}{
@@ -210,6 +226,34 @@ func TestHandleAuthFuncResponsesSingleRedirectURL(t *testing.T) {
 			},
 			wantCode: http.StatusBadRequest,
 		},
+
+		// registration
+		{
+			query: url.Values{
+				"response_type": []string{"code"},
+				"redirect_uri":  []string{"http://client.example.com/callback"},
+				"client_id":     []string{"client.example.com"},
+				"connector_id":  []string{"local"},
+				"register":      []string{"1"},
+				"scope":         []string{"openid"},
+			},
+			baseURL:      url.URL{Scheme: "https", Host: "dex.example.com"}, // Root URL.
+			wantCode:     http.StatusFound,
+			wantLocation: "/register?code=code-2",
+		},
+		{
+			query: url.Values{
+				"response_type": []string{"code"},
+				"redirect_uri":  []string{"http://client.example.com/callback"},
+				"client_id":     []string{"client.example.com"},
+				"connector_id":  []string{"local"},
+				"register":      []string{"1"},
+				"scope":         []string{"openid"},
+			},
+			baseURL:      url.URL{Scheme: "https", Host: "dex.example.com", Path: "/foobar"},
+			wantCode:     http.StatusFound,
+			wantLocation: "/foobar/register?code=code-2",
+		},
 	}
 
 	for i, tt := range tests {
@@ -218,7 +262,7 @@ func TestHandleAuthFuncResponsesSingleRedirectURL(t *testing.T) {
 			t.Fatalf("error making test fixtures: %v", err)
 		}
 
-		hdlr := handleAuthFunc(f.srv, idpcs, nil, true)
+		hdlr := handleAuthFunc(f.srv, tt.baseURL, idpcs, nil, true)
 		w := httptest.NewRecorder()
 		u := fmt.Sprintf("http://server.example.com?%s", tt.query.Encode())
 		req, err := http.NewRequest("GET", u, nil)
@@ -322,7 +366,7 @@ func TestHandleAuthFuncResponsesMultipleRedirectURLs(t *testing.T) {
 	}
 
 	for i, tt := range tests {
-		hdlr := handleAuthFunc(f.srv, idpcs, nil, true)
+		hdlr := handleAuthFunc(f.srv, url.URL{}, idpcs, nil, true)
 		w := httptest.NewRecorder()
 		u := fmt.Sprintf("http://server.example.com?%s", tt.query.Encode())
 		req, err := http.NewRequest("GET", u, nil)