Add auth middleware

auth.go

@@ -45,17 +45,17 @@ func (as *AuthService) Login(username, password string) (string, error) {
 	return signed, nil
 }
 
-func (as *AuthService) ValidateToken(rawToken string) error {
+func (as *AuthService) ValidateToken(rawToken string) (*jwt.StandardClaims, error) {
 	claims := &jwt.StandardClaims{}
 	token, err := jwt.ParseWithClaims(rawToken, claims, func(t *jwt.Token) (interface{}, error) {
 		return as.hmacSecret, nil
 	})
 	if err != nil {
-		return err
+		return nil, err
 	}
 	if !token.Valid {
-		return fmt.Errorf("invalid token")
+		return nil, fmt.Errorf("invalid token")
 	}
 
-	return nil
+	return claims, nil
 }

auth_test.go

@@ -28,11 +28,11 @@ func TestAuth(t *testing.T) {
 			t.Fatalf("Error creating token: %s", err)
 		}
 
-		if err := as.ValidateToken(token); err != nil {
+		if _, err := as.ValidateToken(token); err != nil {
 			t.Fatalf("Error validating token: %s", err)
 		}
 		invalidToken := `eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjE2NDMyMjk3NjMsImp0aSI6ImUzNDk5NWI1LThiZmMtNDQyNy1iZDgxLWFmNmQ3OTRiYzM0YiIsImlhdCI6MTY0MjYyNDk2MywibmJmIjoxNjQyNjI0OTYzLCJzdWIiOiJYdE5Hemt5ZSJ9.VM6dkwSLaBv8cStkWRVVv9ADjdUrHGHrlB7GB7Ly7n8`
-		if err := as.ValidateToken(invalidToken); err == nil {
+		if _, err := as.ValidateToken(invalidToken); err == nil {
 			t.Fatalf("Invalid token passed validation")
 		}
 	})

gpaste-server.toml

@@ -1,4 +1,4 @@
-LogLevel = "INFO"
+LogLevel = "DEBUG"
 URL = "http://paste.example.org"
 ListenAddr = ":8080"
 

http.go

@@ -42,6 +42,7 @@ func NewHTTPServer(cfg *ServerConfig) *HTTPServer {
 	r.Use(middleware.RealIP)
 	r.Use(middleware.RequestID)
 	r.Use(srv.MiddlewareAccessLogger)
+	r.Use(srv.MiddlewareAuthentication)
 	r.Get("/", srv.HandlerIndex)
 	r.Post("/api/file", srv.HandlerAPIFilePost)
 	r.Get("/api/file/{id}", srv.HandlerAPIFileGet)

http_test.go

@@ -137,7 +137,7 @@ func TestHandlers(t *testing.T) {
 			t.Fatalf("Error decoding response: %s", err)
 		}
 
-		if err := hs.Auth.ValidateToken(responseData.Token); err != nil {
+		if _, err := hs.Auth.ValidateToken(responseData.Token); err != nil {
 			t.Fatalf("Unable to validate received token: %s", err)
 		}
 	})

middleware.go

@@ -1,12 +1,21 @@
 package gpaste
 
 import (
+	"context"
+	"fmt"
 	"net/http"
+	"strings"
 	"time"
 
 	"github.com/go-chi/chi/v5/middleware"
 )
 
+type authCtxKey int
+
+const (
+	authCtxUsername authCtxKey = iota
+)
+
 func (s *HTTPServer) MiddlewareAccessLogger(next http.Handler) http.Handler {
 	fn := func(w http.ResponseWriter, r *http.Request) {
 		ww := middleware.NewWrapResponseWriter(w, r.ProtoMajor)
@@ -28,3 +37,51 @@ func (s *HTTPServer) MiddlewareAccessLogger(next http.Handler) http.Handler {
 	}
 	return http.HandlerFunc(fn)
 }
+
+func (s *HTTPServer) MiddlewareAuthentication(next http.Handler) http.Handler {
+	fn := func(w http.ResponseWriter, r *http.Request) {
+		reqID := middleware.GetReqID(r.Context())
+		header := r.Header.Get("Authorization")
+		if header == "" {
+			s.Logger.Debugw("Request has no auth header.", "req_id", reqID)
+			next.ServeHTTP(w, r)
+			return
+		}
+
+		splitHeader := strings.Split(header, "Bearer ")
+		if len(splitHeader) != 2 {
+			s.Logger.Debugw("Request has invalid token.", "req_id", reqID)
+			next.ServeHTTP(w, r)
+			return
+		}
+		token := splitHeader[1]
+
+		claims, err := s.Auth.ValidateToken(token)
+		if err != nil {
+			s.Logger.Debugw("Request has invalid token.", "req_id", reqID)
+			next.ServeHTTP(w, r)
+			return
+		}
+
+		ctx := context.WithValue(r.Context(), authCtxUsername, claims.Subject)
+		withCtx := r.WithContext(ctx)
+		s.Logger.Debugw("Request is authenticated.", "req_id", reqID, "username", claims.Subject)
+
+		next.ServeHTTP(w, withCtx)
+	}
+
+	return http.HandlerFunc(fn)
+}
+
+func UsernameFromRequest(r *http.Request) (string, error) {
+	rawUsername := r.Context().Value(authCtxUsername)
+	if rawUsername == nil {
+
+		return "", fmt.Errorf("no username")
+	}
+	username, ok := rawUsername.(string)
+	if !ok {
+		return "", fmt.Errorf("no username")
+	}
+	return username, nil
+}