http: custom hdr: add custom name iterator

include/libwebsockets/lws-http.h

@@ -494,6 +494,26 @@ LWS_VISIBLE LWS_EXTERN int
 lws_hdr_custom_copy(struct lws *wsi, char *dst, int len, const char *name,
 		    int nlen);
 
+typedef void (*lws_hdr_custom_fe_cb_t)(const char *name, int nlen, void *opaque);
+/**
+ * lws_hdr_custom_name_foreach() - Iterate the custom header names
+ *
+ * \param wsi: websocket connection
+ * \param cb: callback for each custom header name
+ * \param opaque: ignored by lws except to pass to callback
+ *
+ * Lws knows about 100 common http headers, and parses them into indexes when
+ * it recognizes them.  When it meets a header that it doesn't know, it stores
+ * the name and value directly, and you can look them up using
+ * lws_hdr_custom_length() and lws_hdr_custom_copy().
+ * 
+ * This api returns -1 on error else 0. Use lws_hdr_custom_copy() to get the
+ * values of headers. Lws must be built with LWS_WITH_CUSTOM_HEADERS (on by
+ * default) to use this api.
+ */
+LWS_VISIBLE LWS_EXTERN int
+lws_hdr_custom_name_foreach(struct lws *wsi, lws_hdr_custom_fe_cb_t cb, void *opaque);
+
 /**
  * lws_get_urlarg_by_name_safe() - get copy and return length of y for x=y urlargs
  *

lib/roles/http/parsers.c

@@ -656,6 +656,31 @@ lws_hdr_custom_copy(struct lws *wsi, char *dst, int len, const char *name,
 
 	return -1;
 }
+
+int
+lws_hdr_custom_name_foreach(struct lws *wsi, lws_hdr_custom_fe_cb_t cb,
+			    void *custom)
+{
+	ah_data_idx_t ll;
+
+	if (!wsi->http.ah || wsi->mux_substream)
+		return -1;
+
+	ll = wsi->http.ah->unk_ll_head;
+
+	while (ll) {
+		if (ll >= wsi->http.ah->data_length)
+			return -1;
+
+		cb(&wsi->http.ah->data[ll + UHO_NAME],
+		   lws_ser_ru16be((uint8_t *)&wsi->http.ah->data[ll + UHO_NLEN]),
+		   custom);
+
+		ll = lws_ser_ru32be((uint8_t *)&wsi->http.ah->data[ll + UHO_LL]);
+	}
+
+	return 0;
+}
 #endif
 
 char *lws_hdr_simple_ptr(struct lws *wsi, enum lws_token_indexes h)