middleware: equalize lengths of input (#1934)

Signed-off-by: Bobby DeSimone <bobbydesimone@gmail.com>

config/metrics.go

@@ -6,6 +6,7 @@ import (
 
 	"github.com/pomerium/pomerium/internal/httputil"
 	"github.com/pomerium/pomerium/internal/log"
+	"github.com/pomerium/pomerium/internal/middleware"
 	"github.com/pomerium/pomerium/internal/telemetry"
 	"github.com/pomerium/pomerium/internal/telemetry/metrics"
 )
@@ -89,7 +90,7 @@ func (mgr *MetricsManager) updateServer(cfg *Config) {
 	}
 
 	if username, password, ok := cfg.Options.GetMetricsBasicAuth(); ok {
-		handler = httputil.RequireBasicAuth(handler, username, password)
+		handler = middleware.RequireBasicAuth(username, password)(handler)
 	}
 
 	mgr.srv, err = httputil.NewServer(&httputil.ServerOptions{

internal/httputil/handlers.go

@@ -2,7 +2,6 @@ package httputil
 
 import (
 	"bytes"
-	"crypto/subtle"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -65,25 +64,3 @@ func (f HandlerFunc) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		e.ErrorResponse(w, r)
 	}
 }
-
-// RequireBasicAuth creates a new handler that requires basic auth from the client before
-// calling the underlying handler.
-func RequireBasicAuth(handler http.Handler, username, password string) http.Handler {
-	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("WWW-Authenticate", `Basic realm="Restricted"`)
-
-		u, p, ok := r.BasicAuth()
-		if !ok {
-			http.Error(w, http.StatusText(http.StatusUnauthorized), http.StatusUnauthorized)
-			return
-		}
-
-		if subtle.ConstantTimeCompare([]byte(u), []byte(username)) != 1 ||
-			subtle.ConstantTimeCompare([]byte(p), []byte(password)) != 1 {
-			http.Error(w, http.StatusText(http.StatusUnauthorized), http.StatusUnauthorized)
-			return
-		}
-
-		handler.ServeHTTP(w, r)
-	})
-}

internal/middleware/middleware.go

@@ -1,6 +1,8 @@
 package middleware
 
 import (
+	"crypto/sha256"
+	"crypto/subtle"
 	"net/http"
 	"strings"
 	"time"
@@ -75,3 +77,31 @@ func TimeoutHandlerFunc(timeout time.Duration, timeoutError string) func(next ht
 		})
 	}
 }
+
+// RequireBasicAuth creates a new handler that requires basic auth from the client before
+// calling the underlying handler.
+func RequireBasicAuth(username, password string) func(next http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			u, p, ok := r.BasicAuth()
+			if !ok {
+				w.Header().Set("WWW-Authenticate", `Basic realm="Restricted"`)
+				http.Error(w, http.StatusText(http.StatusUnauthorized), http.StatusUnauthorized)
+				return
+			}
+
+			givenUser := sha256.Sum256([]byte(u))
+			givenPass := sha256.Sum256([]byte(p))
+			requiredUser := sha256.Sum256([]byte(username))
+			requiredPass := sha256.Sum256([]byte(password))
+
+			if subtle.ConstantTimeCompare(givenUser[:], requiredUser[:]) != 1 ||
+				subtle.ConstantTimeCompare(givenPass[:], requiredPass[:]) != 1 {
+				w.Header().Set("WWW-Authenticate", `Basic realm="Restricted"`)
+				http.Error(w, http.StatusText(http.StatusUnauthorized), http.StatusUnauthorized)
+				return
+			}
+			next.ServeHTTP(w, r)
+		})
+	}
+}

internal/middleware/middleware_test.go

@@ -155,3 +155,46 @@ func TestValidateSignature(t *testing.T) {
 		})
 	}
 }
+
+func TestRequireBasicAuth(t *testing.T) {
+	t.Parallel()
+
+	fn := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprint(w, http.StatusText(http.StatusOK))
+		w.WriteHeader(http.StatusOK)
+	})
+
+	tests := []struct {
+		name       string
+		givenUser  string
+		givenPass  string
+		wantUser   string
+		wantPass   string
+		wantStatus int
+	}{
+		{"good", "foo", "bar", "foo", "bar", 200},
+		{"bad pass", "foo", "bar", "foo", "buzz", 401},
+		{"bad user", "foo", "bar", "buzz", "bar", 401},
+		{"empty", "", "", "", "", 401}, // don't add auth
+		{"empty user", "", "bar", "", "bar", 200},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			req, err := http.NewRequest(http.MethodGet, "/", nil)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if tt.givenUser != "" || tt.givenPass != "" {
+				req.SetBasicAuth(tt.givenUser, tt.givenPass)
+			}
+
+			rr := httptest.NewRecorder()
+			handler := RequireBasicAuth(tt.wantUser, tt.wantPass)(fn)
+			handler.ServeHTTP(rr, req)
+			if status := rr.Code; status != tt.wantStatus {
+				t.Errorf("RequireBasicAuth() error = %v, wantErr %v\n%v", rr.Result().StatusCode, tt.wantStatus, rr.Body.String())
+			}
+		})
+	}
+}