TitanUpload middleware in contrib/fs

1 files changed, 65 insertions, 0 deletions

diff --git a/contrib/fs/gemini.go b/contrib/fs/gemini.go
index fbf8d08..7549ce6 100644
--- a/contrib/fs/gemini.go
+++ b/contrib/fs/gemini.go
@@ -2,14 +2,79 @@ package fs
 
 import (
 	"context"
+	"crypto/tls"
+	"io"
 	"io/fs"
+	"net/url"
+	"os"
+	"path"
 	"strings"
 	"text/template"
 
 	sr "tildegit.org/tjp/sliderule"
+	"tildegit.org/tjp/sliderule/contrib/tlsauth"
 	"tildegit.org/tjp/sliderule/gemini"
 )
 
+// TitanUpload decorates a handler to implement uploads via the titan protocol.
+//
+// It is a middleware rather than a handler because after the upload is processed,
+// the server is still responsible for generating a response.
+func TitanUpload(approver tlsauth.Approver, rootdir string) sr.Middleware {
+	rootdir = strings.TrimSuffix(rootdir, "/")
+
+	return func(responder sr.Handler) sr.Handler {
+		handler := sr.HandlerFunc(func(ctx context.Context, request *sr.Request) *sr.Response {
+			body := gemini.GetTitanRequestBody(request)
+
+			tmpf, err := os.CreateTemp("", "titan_upload_")
+			if err != nil {
+				return gemini.PermanentFailure(err)
+			}
+
+			if _, err := io.Copy(tmpf, body); err != nil {
+				_ = os.Remove(tmpf.Name())
+				return gemini.PermanentFailure(err)
+			}
+
+			request = cloneRequest(request)
+			request.Path = strings.SplitN(request.Path, ";", 2)[0]
+
+			filepath := strings.TrimPrefix(request.Path, "/")
+			filepath = path.Join(rootdir, filepath)
+			if err := os.Rename(tmpf.Name(), filepath); err != nil {
+				_ = os.Remove(tmpf.Name())
+				return gemini.PermanentFailure(err)
+			}
+
+			return responder.Handle(ctx, request)
+		})
+
+		handler = tlsauth.GeminiAuth(approver)(handler)
+
+		handler = sr.Filter(func(_ context.Context, r *sr.Request) bool {
+			return gemini.GetTitanRequestBody(r) != nil
+		}, nil)(handler)
+
+		return handler
+	}
+}
+
+func cloneRequest(start *sr.Request) *sr.Request {
+	next := &sr.Request{}
+	*next = *start
+
+	next.URL = &url.URL{}
+	*next.URL = *start.URL
+
+	if start.TLSState != nil {
+		next.TLSState = &tls.ConnectionState{}
+		*next.TLSState = *start.TLSState
+	}
+
+	return next
+}
+
 // GeminiFileHandler builds a handler which serves up files from a file system.
 //
 // It only serves responses for paths which do not correspond to directories on disk.