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4864a6859

Sergey Ponomarev

2020-08-15

SUCCESS Duration: 149s

Subject

httpd: Support caching via ETag header

Binary

No binary (build failed)

Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

—

Build Log

(log yok)

Commit Diff GitHub →

networking/httpd.c +54 -3

networking/httpd.c+54 -3

@@ -215,6 +215,19 @@
	//config: Makes httpd send files using GZIP content encoding if the
	//config: client supports it and a pre-compressed <file>.gz exists.
	//config:
+	//config:config FEATURE_HTTPD_ETAG
+	//config: bool "Support caching via ETag header"
+	//config: default y
+	//config: depends on HTTPD
+	//config: help
+	//config: If server responds with ETag then next time client (browser)
+	//config: resend it via If-None-Match header.
+	//config: Then httpd will check if file wasn't modified and if not,
+	//config: return 304 Not Modified status code.
+	//config: The ETag value is constructed from last modification date
+	//config: in unix epoch, and size: "hex(last_mod)-hex(file_size)".
+	//config: It's not completely reliable as hash functions but fair enough.
+	//config:
	//config:config FEATURE_HTTPD_LAST_MODIFIED
	//config: bool "Add Last-Modified header to response"
	//config: default y
@@ -328,6 +341,7 @@ enum {
	HTTP_OK = 200,
	HTTP_PARTIAL_CONTENT = 206,
	HTTP_MOVED_TEMPORARILY = 302,
+	HTTP_NOT_MODIFIED = 304,
	HTTP_BAD_REQUEST = 400, /* malformed syntax */
	HTTP_UNAUTHORIZED = 401, /* authentication needed, respond with auth hdr */
	HTTP_NOT_FOUND = 404,
@@ -345,7 +359,6 @@ enum {
	HTTP_NO_CONTENT = 204,
	HTTP_MULTIPLE_CHOICES = 300,
	HTTP_MOVED_PERMANENTLY = 301,
-	HTTP_NOT_MODIFIED = 304,
	HTTP_PAYMENT_REQUIRED = 402,
	HTTP_BAD_GATEWAY = 502,
	HTTP_SERVICE_UNAVAILABLE = 503, /* overload, maintenance */
@@ -358,6 +371,9 @@ static const uint16_t http_response_type[] ALIGN2 = {
	HTTP_PARTIAL_CONTENT,
	#endif
	HTTP_MOVED_TEMPORARILY,
+	#if ENABLE_FEATURE_HTTPD_ETAG
+	HTTP_NOT_MODIFIED,
+	#endif
	HTTP_REQUEST_TIMEOUT,
	HTTP_NOT_IMPLEMENTED,
	#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
@@ -374,7 +390,6 @@ static const uint16_t http_response_type[] ALIGN2 = {
	HTTP_NO_CONTENT,
	HTTP_MULTIPLE_CHOICES,
	HTTP_MOVED_PERMANENTLY,
-	HTTP_NOT_MODIFIED,
	HTTP_BAD_GATEWAY,
	HTTP_SERVICE_UNAVAILABLE,
	#endif
@@ -389,6 +404,9 @@ static const struct {
	{ "Partial Content", NULL },
	#endif
	{ "Found", NULL },
+	#if ENABLE_FEATURE_HTTPD_ETAG
+	{ "Not Modified" },
+	#endif
	{ "Request Timeout", "No request appeared within 60 seconds" },
	{ "Not Implemented", "The requested method is not recognized" },
	#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
@@ -405,7 +423,6 @@ static const struct {
	{ "No Content" },
	{ "Multiple Choices" },
	{ "Moved Permanently" },
-	{ "Not Modified" },
	{ "Bad Gateway", "" },
	{ "Service Unavailable", "" },
	#endif
@@ -419,6 +436,9 @@ struct globals {
	smallint content_gzip;
	#endif
	time_t last_mod;
+	#if ENABLE_FEATURE_HTTPD_ETAG
+	char *if_none_match;
+	#endif
	char rmt_ip_str; / for $REMOTE_ADDR and $REMOTE_PORT */
	const char *bind_addr_or_port;

@@ -453,6 +473,9 @@ struct globals {
	#define sizeof_hdr_buf COMMON_BUFSIZE
	char *hdr_ptr;
	int hdr_cnt;
+	#if ENABLE_FEATURE_HTTPD_ETAG
+	char etag[sizeof("'%llx-%llx'") + 2 * sizeof(long long)*3];
+	#endif
	#if ENABLE_FEATURE_HTTPD_ERROR_PAGES
	const char *http_error_page[ARRAY_SIZE(http_response_type)];
	#endif
@@ -1208,6 +1231,10 @@ static void send_headers(unsigned responseNum)
	#if ENABLE_FEATURE_HTTPD_LAST_MODIFIED
	"Last-Modified: %s\r\n"
	#endif
+	#if ENABLE_FEATURE_HTTPD_ETAG
+	"ETag: %s\r\n"
+	#endif
+
	/* Because of 4.4 (5), we can forgo sending of "Content-Length"
	* since we close connection afterwards, but it helps clients
	* to e.g. estimate download times, show progress bars etc.
@@ -1217,6 +1244,9 @@ static void send_headers(unsigned responseNum)
	"Content-Length: %"OFF_FMT"u\r\n",
	#if ENABLE_FEATURE_HTTPD_LAST_MODIFIED
	date_str,
+	#endif
+	#if ENABLE_FEATURE_HTTPD_ETAG
+	G.etag,
	#endif
	file_size
	);
@@ -1730,6 +1760,7 @@ static NOINLINE void send_file_and_exit(const char *url, int what)
	}
	} else {
	fd = open(url, O_RDONLY);
+	/* file_size and last_mod are already populated */
	}
	if (fd < 0) {
	if (DEBUG)
@@ -1741,6 +1772,19 @@ static NOINLINE void send_file_and_exit(const char *url, int what)
	send_headers_and_exit(HTTP_NOT_FOUND);
	log_and_exit();
	}
+	#if ENABLE_FEATURE_HTTPD_ETAG
+	/* ETag is "hex(last_mod)-hex(file_size)" e.g. "5e132e20-417" */
+	sprintf(G.etag, "\"%llx-%llx\"", (unsigned long long)last_mod, (unsigned long long)file_size);
+
+	if (G.if_none_match) {
+	if (DEBUG)
+	bb_perror_msg("If-None-Match and file's ETag are: '%s' '%s'\n", G.if_none_match, G.etag);
+	/* Weak ETag comparision.
+	* If-None-Match may have many ETags but they are quoted so we can use simple substring search */
+	if (strstr(G.if_none_match, G.etag))
+	send_headers_and_exit(HTTP_NOT_MODIFIED);
+	}
+	#endif
	/* If you want to know about EPIPE below
	* (happens if you abort downloads from local httpd): */
	signal(SIGPIPE, SIG_IGN);
@@ -2480,6 +2524,13 @@ static void handle_incoming_and_exit(const len_and_sockaddr *fromAddr)
	continue;
	}
	#endif
+	#if ENABLE_FEATURE_HTTPD_ETAG
+	if (STRNCASECMP(iobuf, "If-None-Match:") == 0) {
+	free(G.if_none_match);
+	G.if_none_match = xstrdup(skip_whitespace(iobuf + sizeof("If-None-Match:") - 1));
+	continue;
+	}
+	#endif
	#if ENABLE_FEATURE_HTTPD_CGI
	if (cgi_type != CGI_NONE) {
	bool ct = (STRNCASECMP(iobuf, "Content-Type:") == 0);