From 8229f31f70ecdbe03d03c96cba17d6ee85397bca Mon Sep 17 00:00:00 2001
From: tjpcc <tjp@ctrl-c.club>
Date: Fri, 20 Jan 2023 10:58:35 -0700
Subject: "tlsauth" contrib package

This package adds authentication middlewares via TLS client
certificates.
---
 contrib/tlsauth/gemini.go | 58 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 contrib/tlsauth/gemini.go

(limited to 'contrib/tlsauth/gemini.go')

diff --git a/contrib/tlsauth/gemini.go b/contrib/tlsauth/gemini.go
new file mode 100644
index 0000000..0db89de
--- /dev/null
+++ b/contrib/tlsauth/gemini.go
@@ -0,0 +1,58 @@
+package tlsauth
+
+import (
+	"context"
+
+	"tildegit.org/tjp/gus"
+	"tildegit.org/tjp/gus/gemini"
+)
+
+// GeminiAuth builds an authentication middleware from approval criteria.
+//
+// If a request does not contain a client certificate it will be rejected
+// with a "60 certificate required" response. If the client identity does
+// not pass the approver it will be rejected with "62 certificate invalid".
+func GeminiAuth(approver Approver) gus.Middleware {
+	return func(inner gus.Handler) gus.Handler {
+		return func(ctx context.Context, request *gus.Request) *gus.Response {
+			identity := Identity(request)
+			if identity == nil {
+				return geminiMissingCert(ctx, request)
+			}
+			if !approver(identity) {
+				return geminiCertNotAuthorized(ctx, request)
+			}
+
+			return inner(ctx, request)
+		}
+	}
+}
+
+// GeminiOptionalAuth builds auth middleware which doesn't require an identity.
+//
+// If there is no client certificate the request will pass through the middleware.
+// It will only be rejected with "62 certificate invalid" if there *is* a client
+// certificate, but it fails the approval.
+func GeminiOptionalAuth(approver Approver) gus.Middleware {
+	return func(inner gus.Handler) gus.Handler {
+		return func(ctx context.Context, request *gus.Request) *gus.Response {
+			identity := Identity(request)
+			if identity != nil && !approver(identity) {
+				return geminiCertNotAuthorized(ctx, request)
+			}
+
+			return inner(ctx, request)
+		}
+	}
+}
+
+// GeminiRequireCertificate is a middleware that only requires a client certificate.
+var GeminiRequireCertificate = GeminiAuth(Allow)
+
+func geminiMissingCert(_ context.Context, _ *gus.Request) *gus.Response {
+	return gemini.RequireCert("A client certificate is required.")
+}
+
+func geminiCertNotAuthorized(_ context.Context, _ *gus.Request) *gus.Response {
+	return gemini.CertAuthFailure("Client certificate not authorized.")
+}
-- 
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