Send WS handshake using event loop instead of write(2)

ws_handshake_reply was sending its response using a single write(2) call
without error-checking, which could well send only part of it and leave
the client hanging. This change creates an HTTP response object and
schedules it for writing using the event loop.

Tested with Valgrind, no memory is leaked.

src/websocket.c

@@ -89,7 +89,6 @@ ws_compute_handshake(struct http_client *c, char *out, size_t *out_sz) {
 int
 ws_handshake_reply(struct http_client *c) {
 
-	int ret;
 	char sha1_handshake[40];
 	char *buffer = NULL, *p;
 	const char *origin = NULL, *host = NULL;
@@ -135,7 +134,7 @@ ws_handshake_reply(struct http_client *c) {
 
 	p = buffer = malloc(sz);
 	if(!p) {
-		slog(c->s, WEBDIS_ERROR, "Failed to allocate memory for WS handshake", 0);
+		slog(c->s, WEBDIS_ERROR, "Failed to allocate buffer for WS handshake", 0);
 		return -1;
 	}
 
@@ -171,10 +170,19 @@ ws_handshake_reply(struct http_client *c) {
 	memcpy(p, template4, sizeof(template4)-1);
 	p += sizeof(template4)-1;
 
-	/* send data to client */
-	ret = write(c->fd, buffer, sz); /* FIXME: this needs to use the event loop */
-	(void)ret;
+	/* build HTTP response object by hand, since we have the full response already */
+	struct http_response *r = calloc(1, sizeof(struct http_response));
+	if(!r) {
+		slog(c->s, WEBDIS_ERROR, "Failed to allocate response for WS handshake", 0);
 		free(buffer);
+		return -1;
+	}
+	r->w = c->w;
+	r->keep_alive = 1;
+	r->out = buffer;
+	r->out_sz = sz;
+	r->sent = 0;
+	http_schedule_write(c->fd, r); /* will free buffer and response once sent */
 
 	return 0;
 }