feat(server): customizable authz endpoints (#4296)

This allows users to customize the authz endpoints.

Closes #2753, Fixes #3716

Co-authored-by: Amir Zarrinkafsh <nightah@me.com>

1 files changed, 55 insertions, 0 deletions

diff --git a/internal/handlers/handler_authz_impl_forwardauth.go b/internal/handlers/handler_authz_impl_forwardauth.go
new file mode 100644
index 000000000..a042c13bb
--- /dev/null
+++ b/internal/handlers/handler_authz_impl_forwardauth.go
@@ -0,0 +1,55 @@
+package handlers
+
+import (
+	"fmt"
+	"net/url"
+
+	"github.com/valyala/fasthttp"
+
+	"github.com/authelia/authelia/v4/internal/authorization"
+	"github.com/authelia/authelia/v4/internal/middlewares"
+)
+
+func handleAuthzGetObjectForwardAuth(ctx *middlewares.AutheliaCtx) (object authorization.Object, err error) {
+	protocol, host, uri := ctx.XForwardedProto(), ctx.XForwardedHost(), ctx.XForwardedURI()
+
+	var (
+		targetURL *url.URL
+		method    []byte
+	)
+
+	if targetURL, err = getRequestURIFromForwardedHeaders(protocol, host, uri); err != nil {
+		return object, fmt.Errorf("failed to get target URL: %w", err)
+	}
+
+	if method = ctx.XForwardedMethod(); len(method) == 0 {
+		return object, fmt.Errorf("header 'X-Forwarded-Method' is empty")
+	}
+
+	if hasInvalidMethodCharacters(method) {
+		return object, fmt.Errorf("header 'X-Forwarded-Method' with value '%s' has invalid characters", method)
+	}
+
+	return authorization.NewObjectRaw(targetURL, method), nil
+}
+
+func handleAuthzUnauthorizedForwardAuth(ctx *middlewares.AutheliaCtx, authn *Authn, redirectionURL *url.URL) {
+	var (
+		statusCode int
+	)
+
+	switch {
+	case ctx.IsXHR() || !ctx.AcceptsMIME("text/html"):
+		statusCode = fasthttp.StatusUnauthorized
+	default:
+		switch authn.Object.Method {
+		case fasthttp.MethodGet, fasthttp.MethodOptions, fasthttp.MethodHead:
+			statusCode = fasthttp.StatusFound
+		default:
+			statusCode = fasthttp.StatusSeeOther
+		}
+	}
+
+	ctx.Logger.Infof("Access to %s (method %s) is not authorized to user %s, responding with status code %d with location redirect to %s", authn.Object.String(), authn.Method, authn.Username, statusCode, redirectionURL)
+	ctx.SpecialRedirect(redirectionURL.String(), statusCode)
+}