Add support for "real" entropy from /dev/[u]random (fixes #1977)

git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@2524 152afb58-edef-0310-8abb-c4023f1b3aa9

NEWS

@@ -50,6 +50,7 @@ NEWS
   * Add "lighty.req_env" table to mod_magnet for setting/getting environment values for cgi (fixes #1967, thx presbrey)
   * Fix segfault in mod_expire after failed config parsing (fixes #1992)
   * Add ssi.content-type option (default text/html, fixes #615)
+  * Add support for "real" entropy from /dev/[u]random (fixes #1977)
 
 - 1.4.22 - 2009-03-07
   * Fix wrong lua type for CACHE_MISS/CACHE_HIT in mod_cml (fixes #533)

src/base.h

@@ -587,6 +587,9 @@ typedef struct server {
 	time_t last_generated_debug_ts;
 	time_t startup_ts;
 
+	char entropy[8]; /* from /dev/[u]random if possible, otherwise rand() */
+	char is_real_entropy; /* whether entropy is from /dev/[u]random */
+
 	buffer *ts_debug_str;
 	buffer *ts_date_str;
 

src/http_auth.c

@@ -1188,6 +1188,7 @@ int http_auth_digest_generate_nonce(server *srv, mod_auth_plugin_data *p, buffer
 	/* we assume sizeof(time_t) == 4 here, but if not it ain't a problem at all */
 	LI_ltostr(hh, srv->cur_ts);
 	MD5_Update(&Md5Ctx, (unsigned char *)hh, strlen(hh));
+	MD5_Update(&Md5Ctx, (unsigned char *)srv->entropy, sizeof(srv->entropy));
 	LI_ltostr(hh, rand());
 	MD5_Update(&Md5Ctx, (unsigned char *)hh, strlen(hh));
 

src/mod_usertrack.c

@@ -229,6 +229,7 @@ URIHANDLER_FUNC(mod_usertrack_uri_handler) {
 	/* we assume sizeof(time_t) == 4 here, but if not it ain't a problem at all */
 	LI_ltostr(hh, srv->cur_ts);
 	MD5_Update(&Md5Ctx, (unsigned char *)hh, strlen(hh));
+	MD5_Update(&Md5Ctx, (unsigned char *)srv->entropy, sizeof(srv->entropy));
 	LI_ltostr(hh, rand());
 	MD5_Update(&Md5Ctx, (unsigned char *)hh, strlen(hh));
 

src/server.c

@@ -169,6 +169,7 @@ static void daemonize(void) {
 
 static server *server_init(void) {
 	int i;
+	FILE *frandom = NULL;
 
 	server *srv = calloc(1, sizeof(*srv));
 	assert(srv);
@@ -209,6 +210,19 @@ static server *server_init(void) {
 		srv->mtime_cache[i].str = buffer_init();
 	}
 
+	if ((NULL != (frandom = fopen("/dev/urandom", "rb")) || NULL != (frandom = fopen("/dev/random", "rb")))
+	            && 1 == fread(srv->entropy, sizeof(srv->entropy), 1, frandom)) {
+		srand(*(unsigned int*)srv->entropy);
+		srv->is_real_entropy = 1;
+	} else {
+		unsigned int j;
+		srand(time(NULL) ^ getpid());
+		srv->is_real_entropy = 0;
+		for (j = 0; j < sizeof(srv->entropy); j++)
+			srv->entropy[j] = rand();
+	}
+	if (frandom) fclose(frandom);
+
 	srv->cur_ts = time(NULL);
 	srv->startup_ts = srv->cur_ts;