Keep the query string across the about redirects

The hop to the trailing-slash form of the about page, and the hop back
to the summary of a repository without a readme, were built from the
path alone, so a request for the about page of another branch landed
on the default one. The query goes into the Location line as the
client sent it, with any byte a header cannot carry percent-encoded.

1 file changed, 22 insertions, 0 deletions

diff --git a/source/html.c b/source/html.c
index a1d244b..96b1b52 100644
--- a/source/html.c
+++ b/source/html.c
@@ -339,6 +339,28 @@ void html_header_arg_in_quotes(const char *txt)
 		html(txt);
 }
 
+/*
+ * A query string goes into a header the way it arrived, already encoded by
+ * the client, except that a byte a header line cannot carry is percent-encoded
+ * so the line stays one line.
+ */
+void html_header_query(const char *txt)
+{
+	const char *p = txt;
+
+	while (p && *p) {
+		unsigned char c = *p;
+		if (c <= ' ' || c >= 0x7f) {
+			html_raw(txt, p - txt);
+			html(url_escape_table[c]);
+			txt = p + 1;
+		}
+		p++;
+	}
+	if (p != txt)
+		html(txt);
+}
+
 void html_hidden(const char *name, const char *value)
 {
 	html("<input type='hidden' name='");