[PATCH] Handle If-None-Match HTTP header in plain view

Mon Aug 11 22:53:23 CEST 2014

We are sending Etag to clients but this header is basically unusefulness
if the server doesn't tell the client if the content has been changed or
not for a given Path/Etag pair.

Signed-off-by: Damián Nohales <damiannohales at gmail.com>
---
 cgit.c      |  1 +
 cgit.h      |  1 +
 ui-plain.c  | 41 +++++++++++++++++++++--------------------
 ui-shared.c | 20 ++++++++++++++++++++
 ui-shared.h |  1 +
 5 files changed, 44 insertions(+), 20 deletions(-)

diff --git a/cgit.c b/cgit.c
index 8c4517d..7af7712 100644
--- a/cgit.c
+++ b/cgit.c
@@ -385,6 +385,7 @@ static void prepare_context(void)
 	ctx.env.server_port = getenv("SERVER_PORT");
 	ctx.env.http_cookie = getenv("HTTP_COOKIE");
 	ctx.env.http_referer = getenv("HTTP_REFERER");
+	ctx.env.if_none_match = getenv("HTTP_IF_NONE_MATCH");
 	ctx.env.content_length = getenv("CONTENT_LENGTH") ? strtoul(getenv("CONTENT_LENGTH"), NULL, 10) : 0;
 	ctx.env.authenticated = 0;
 	ctx.page.mimetype = "text/html";
diff --git a/cgit.h b/cgit.h
index 0badc64..eddd4c7 100644
--- a/cgit.h
+++ b/cgit.h
@@ -282,6 +282,7 @@ struct cgit_environment {
 	const char *server_port;
 	const char *http_cookie;
 	const char *http_referer;
+	const char *if_none_match;
 	unsigned int content_length;
 	int authenticated;
 };
diff --git a/ui-plain.c b/ui-plain.c
index 30fff89..a08dc5b 100644
--- a/ui-plain.c
+++ b/ui-plain.c
@@ -103,8 +103,8 @@ static int print_object(const unsigned char *sha1, const char *path)
 	ctx.page.filename = path;
 	ctx.page.size = size;
 	ctx.page.etag = sha1_to_hex(sha1);
-	cgit_print_http_headers();
-	html_raw(buf, size);
+	if (!cgit_print_http_headers_matching_etag())
+		html_raw(buf, size);
 	/* If we allocated this, then casting away const is safe. */
 	if (freemime)
 		free((char*) ctx.page.mimetype);
@@ -128,24 +128,25 @@ static void print_dir(const unsigned char *sha1, const char *base,
 	fullpath = buildpath(base, baselen, path);
 	slash = (fullpath[0] == '/' ? "" : "/");
 	ctx.page.etag = sha1_to_hex(sha1);
-	cgit_print_http_headers();
-	htmlf("<html><head><title>%s", slash);
-	html_txt(fullpath);
-	htmlf("</title></head>\n<body>\n<h2>%s", slash);
-	html_txt(fullpath);
-	html("</h2>\n<ul>\n");
-	len = strlen(fullpath);
-	if (len > 1) {
-		fullpath[len - 1] = 0;
-		slash = strrchr(fullpath, '/');
-		if (slash)
-			*(slash + 1) = 0;
-		else
-			fullpath = NULL;
-		html("<li>");
-		cgit_plain_link("../", NULL, NULL, ctx.qry.head, ctx.qry.sha1,
-				fullpath);
-		html("</li>\n");
+	if (!cgit_print_http_headers_matching_etag()) {
+		htmlf("<html><head><title>%s", slash);
+		html_txt(fullpath);
+		htmlf("</title></head>\n<body>\n<h2>%s", slash);
+		html_txt(fullpath);
+		html("</h2>\n<ul>\n");
+		len = strlen(fullpath);
+		if (len > 1) {
+			fullpath[len - 1] = 0;
+			slash = strrchr(fullpath, '/');
+			if (slash)
+				*(slash + 1) = 0;
+			else
+				fullpath = NULL;
+			html("<li>");
+			cgit_plain_link("../", NULL, NULL, ctx.qry.head, ctx.qry.sha1,
+					fullpath);
+			html("</li>\n");
+		}
 	}
 	free(fullpath);
 }
diff --git a/ui-shared.c b/ui-shared.c
index 9dde0a3..84c7efd 100644
--- a/ui-shared.c
+++ b/ui-shared.c
@@ -661,6 +661,26 @@ void cgit_print_http_headers(void)
 		exit(0);
 }
 
+int cgit_print_http_headers_matching_etag(void)
+{
+	int match = 0;
+	char *etag;
+	if (ctx.page.etag && ctx.env.if_none_match) {
+		etag = fmtalloc("\"%s\"", ctx.page.etag);
+		if (!strcmp(etag, ctx.env.if_none_match)) {
+			ctx.page.status = 304;
+			ctx.page.statusmsg = "Not Modified";
+			ctx.page.mimetype = NULL;
+			ctx.page.size = 0;
+			ctx.page.filename = NULL;
+			match = 1;
+		}
+		free(etag);
+	}
+	cgit_print_http_headers();
+	return match;
+}
+
 void cgit_print_docstart(void)
 {
 	if (ctx.cfg.embedded) {
diff --git a/ui-shared.h b/ui-shared.h
index 3e7a91b..e279f42 100644
--- a/ui-shared.h
+++ b/ui-shared.h
@@ -60,6 +60,7 @@ extern void cgit_vprint_error(const char *fmt, va_list ap);
 extern void cgit_print_date(time_t secs, const char *format, int local_time);
 extern void cgit_print_age(time_t t, time_t max_relative, const char *format);
 extern void cgit_print_http_headers(void);
+extern int cgit_print_http_headers_matching_etag(void);
 extern void cgit_print_docstart(void);
 extern void cgit_print_docend();
 extern void cgit_print_pageheader(void);
-- 
2.0.4

