Index: filed.c
==================================================================
--- filed.c
+++ filed.c
@@ -50,10 +50,11 @@
 	int fd;
 	off_t len;
 	char *lastmod;
 	char lastmod_b[64];
 	const char *type;
+	char etag[64];
 };
 
 /* Request variables */
 struct filed_http_request {
 	/** Buffers **/
@@ -156,26 +157,45 @@
 }
 
 /* Initialize process */
 static int filed_init(unsigned int cache_size) {
 	static int called = 0;
+	unsigned int random_value = 0;
 	int cache_ret;
+	int random_fd;
 
 	if (called) {
 		return(0);
 	}
 
 	called = 1;
 
+	/* Attempt to lock all memory to physical RAM (but don't care if we can't) */
 	mlockall(MCL_CURRENT | MCL_FUTURE);
 
+	/* Ignore SIGPIPE */
 	signal(SIGPIPE, SIG_IGN);
 
+	/* Initialize cache structure */
 	cache_ret = filed_init_cache(cache_size);
 	if (cache_ret != 0) {
 		return(cache_ret);
 	}
+
+	/* Initialize random number generator */
+	random_fd = open("/dev/urandom", O_RDONLY);
+	if (random_fd >= 0) {
+		read(random_fd, &random_value, sizeof(random_value));
+
+		close(random_fd);
+	}
+
+	random_value ^= getpid();
+	random_value ^= getuid();
+	random_value ^= time(NULL);
+
+	srandom(random_value);
 
 	return(0);
 }
 
 /* Listen on a particular address/port */
@@ -499,10 +519,20 @@
 
 #include "filed-mime-types.h"
 
 	return(FILED_DEFAULT_TYPE);
 }
+
+/* Generate a unique identifier */
+static void filed_generate_etag(char *etag, size_t length) {
+	snprintf(etag, length, "%llx%llx%llx%llx",
+		(unsigned long long) random(),
+		(unsigned long long) random(),
+		(unsigned long long) random(),
+		(unsigned long long) random()
+	);
+}
 
 /* Open a file and return file information */
 static struct filed_fileinfo *filed_open_file(const char *path, struct filed_fileinfo *buffer) {
 	struct filed_fileinfo *cache;
 	const char *open_path;
@@ -546,10 +576,11 @@
 
 		cache->fd = fd;
 		cache->len = len;
 		strcpy(cache->path, path);
 		cache->type = filed_determine_mimetype(open_path);
+		filed_generate_etag(cache->etag, sizeof(cache->etag));
 
 		/* XXX:TODO: Determine */
 		cache->lastmod = filed_format_time(cache->lastmod_b, sizeof(cache->lastmod_b), time(NULL) - 30);
 	} else {
 		filed_log_msg_debug("Cache hit for idx: %lu: PATH \"%s\"", (unsigned long) cache_idx, path);
@@ -568,10 +599,11 @@
 
 	buffer->fd = fd;
 	buffer->len = cache->len;
 	buffer->type = cache->type;
 	memcpy(buffer->lastmod_b, cache->lastmod_b, sizeof(buffer->lastmod_b));
+	memcpy(buffer->etag, cache->etag, sizeof(buffer->etag));
 	buffer->lastmod = buffer->lastmod_b + (cache->lastmod - cache->lastmod_b);
 
 	pthread_mutex_unlock(&cache->mutex);
 
 	return(buffer);
@@ -796,16 +828,17 @@
 			request->headers.range.offset = 0;
 			request->headers.range.length = fileinfo->len;
 		}
 
 		if (http_code > 0) {
-			fprintf(fp, "HTTP/1.1 %i OK\r\nDate: %s\r\nServer: filed\r\nLast-Modified: %s\r\nContent-Length: %llu\r\nAccept-Ranges: bytes\r\nContent-Type: %s\r\nConnection: close\r\n",
+			fprintf(fp, "HTTP/1.1 %i OK\r\nDate: %s\r\nServer: filed\r\nLast-Modified: %s\r\nContent-Length: %llu\r\nAccept-Ranges: bytes\r\nContent-Type: %s\r\nConnection: close\r\nETag: \"%s\"\r\n",
 				http_code,
 				date_current,
 				fileinfo->lastmod,
 				(unsigned long long) request->headers.range.length,
-				fileinfo->type
+				fileinfo->type,
+				fileinfo->etag
 			);
 			if (http_code == 206) {
 				fprintf(fp, "Content-Range: bytes %llu-%llu/%llu\r\n",
 					(unsigned long long) request->headers.range.offset,
 					(unsigned long long) (request->headers.range.offset + request->headers.range.length - 1),