From 5377c2941fb4b7242307e461b60202c6615596ec Mon Sep 17 00:00:00 2001
From: Solderpunk <solderpunk@sdf.org>
Date: Sun, 28 Jun 2020 00:12:32 +0200
Subject: [PATCH] Allow overriding MIME types based on path regexes.

---
 README.md  |  1 +
 config.go  |  1 +
 handler.go | 13 ++++++++++---
 3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/README.md b/README.md
index 7bebcce..dac5489 100644
--- a/README.md
+++ b/README.md
@@ -92,6 +92,7 @@ The following options can be set in `/etc/molly.conf`:
 * `LogPath`: Path to log file (default value `molly.log`).  Note that
   all intermediate directories must exist, Molly Brown won't create
   them for you.
+* `MimeOverrides`: A map from path regexs to MIME types.  If the path of a file which is about to be served matches the regex, the specified MIME type will be used instead of one inferred from the filename extension.
 * `DirectorySort`: A string specifying how to sort files in automatically generated directory listings.  Must be one of "Name", "Size" or "Time" (default value "Name").
 * `DirectoryReverse` (boolean): if true, automatically generated directory listings will list files in descending order of whatever `DirectorySort` is set to (default value false).
 * `DirectoryTitles` (boolean): if true, automatically generated directory listings will use the first top-level heading (i.e. line beginning with "# ") in files with an extension of `GeminiExt` instead of the filename (default value false).
diff --git a/config.go b/config.go
index 5370357..7477c91 100644
--- a/config.go
+++ b/config.go
@@ -17,6 +17,7 @@ type Config struct {
 	LogPath          string
 	TempRedirects    map[string]string
 	PermRedirects    map[string]string
+	MimeOverrides    map[string]string
 	CGIPaths         []string
 	SCGIPaths        map[string]string
 	DirectorySort    string
diff --git a/handler.go b/handler.go
index b45bae6..4d25a1f 100644
--- a/handler.go
+++ b/handler.go
@@ -380,14 +380,21 @@ func serveFile(path string, log *LogEntry, conn net.Conn, config Config) {
 	} else {
 		mimeType = mime.TypeByExtension(ext)
 	}
-	// Add lang parameter
-	if mimeType == "text/gemini" && config.DefaultLang != "" {
-		mimeType += "; lang=" + config.DefaultLang
+	// Override extension-based MIME type
+	for pathRegex, newType := range config.MimeOverrides {
+		overridden, err := regexp.Match(pathRegex, []byte(path))
+		if err == nil && overridden {
+			mimeType = newType
+		}
 	}
 	// Set a generic MIME type if the extension wasn't recognised
 	if mimeType == "" {
 		mimeType = "application/octet-stream"
 	}
+	// Add lang parameter
+	if mimeType == "text/gemini" && config.DefaultLang != "" {
+		mimeType += "; lang=" + config.DefaultLang
+	}
 
 	contents, err := ioutil.ReadFile(path)
 	if err != nil {