httpauth-jwt/auth.go

package httpauthjwt

import (
	"net/http"
	"path"
	"strings"

	"github.com/golang-jwt/jwt/v5"

	httpauthmw "code.nochebuena.dev/go/httpauth"
)

// AuthMiddleware verifies the Bearer access token and injects uid + claims into
// the request context via httpauth.SetTokenData. Downstream middleware
// (EnrichmentMiddleware, AuthzMiddleware, ClaimsPermissionProvider) from
// code.nochebuena.dev/go/httpauth reads them transparently.
//
// Accepts a Verifier — pass a Signer or a NewRSAPublicKeyVerifier depending on
// whether the service issues tokens.
//
// Requests to publicPaths are skipped without token verification (wildcards
// supported via path.Match). Returns 401 on missing, invalid, or expired tokens.
func AuthMiddleware(verifier Verifier, publicPaths []string) func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			for _, pattern := range publicPaths {
				if matched, _ := path.Match(pattern, r.URL.Path); matched {
					next.ServeHTTP(w, r)
					return
				}
			}

			authHeader := r.Header.Get("Authorization")
			if !strings.HasPrefix(authHeader, "Bearer ") {
				httpauthmw.WriteJSONError(w, http.StatusUnauthorized, "UNAUTHENTICATED", "unauthorized")
				return
			}
			tokenStr := strings.TrimPrefix(authHeader, "Bearer ")

			token, err := verifier.Verify(tokenStr)
			if err != nil {
				httpauthmw.WriteJSONError(w, http.StatusUnauthorized, "UNAUTHENTICATED", "unauthorized")
				return
			}

			claims, ok := token.Claims.(jwt.MapClaims)
			if !ok {
				httpauthmw.WriteJSONError(w, http.StatusUnauthorized, "UNAUTHENTICATED", "unauthorized")
				return
			}

			uid, _ := claims["sub"].(string)
			if uid == "" {
				httpauthmw.WriteJSONError(w, http.StatusUnauthorized, "UNAUTHENTICATED", "unauthorized")
				return
			}

			ctx := httpauthmw.SetTokenData(r.Context(), uid, map[string]any(claims))
			next.ServeHTTP(w, r.WithContext(ctx))
		})
	}
}