fix(ws_transport): correct split header bytes

When the underlying transport returns header,
length, or mask bytes early, again call the
underlying transport.

This solves the WS parser getting offset when
the server sends a burst of frames where the
last WS header is split across packet boundaries,
so fewer than the needed bytes may be available.

components/tcp_transport/transport_ws.c

@@ -133,6 +133,33 @@ static int esp_transport_read_internal(transport_ws_t *ws, char *buffer, int len
     return to_read;
 }
 
+static int esp_transport_read_blocking(transport_ws_t *ws, char *buffer, int len, int timeout_ms)
+{
+    int orig_len = len;
+    int did_read = 0;
+
+    //Sometimes we get 1B/read, sometimes we need 8B?
+    //Never seen this need >2 reads, better be safe though - need those headers.
+    const unsigned MAX_ATTEMPT = 8;
+    //TODO: change this(or the underlying transports) to retry only until timeout_ms expires.
+    unsigned attempt = 0;
+    for(attempt = 0; attempt < MAX_ATTEMPT && len > 0; ++attempt){
+        int tmp = esp_transport_read_internal(ws, buffer, len, timeout_ms);
+        if(tmp < 0){
+            return tmp;
+        }
+
+        buffer += tmp;
+        len -= tmp;
+        did_read += tmp;
+    }
+
+    if(attempt > 1){
+        ESP_LOGI(TAG, "tried %u attempts to read %i bytes. did read %i bytes", attempt, orig_len, did_read);
+    }
+    return did_read;
+}
+
 static char *trimwhitespace(char *str)
 {
     char *end;
@@ -486,7 +513,7 @@ static int ws_read_header(esp_transport_handle_t t, char *buffer, int len, int t
     // Receive and process header first (based on header size)
     int header = 2;
     int mask_len = 4;
-    if ((rlen = esp_transport_read_internal(ws, data_ptr, header, timeout_ms)) <= 0) {
+    if ((rlen = esp_transport_read_blocking(ws, data_ptr, header, timeout_ms)) < header) {
         ESP_LOGE(TAG, "Error read data");
         return rlen;
     }
@@ -500,15 +527,15 @@ static int ws_read_header(esp_transport_handle_t t, char *buffer, int len, int t
     ESP_LOGD(TAG, "Opcode: %d, mask: %d, len: %d", ws->frame_state.opcode, mask, payload_len);
     if (payload_len == 126) {
         // headerLen += 2;
-        if ((rlen = esp_transport_read_internal(ws, data_ptr, header, timeout_ms)) <= 0) {
+        if ((rlen = esp_transport_read_blocking(ws, data_ptr, header, timeout_ms)) < header) {
             ESP_LOGE(TAG, "Error read data");
             return rlen;
         }
         payload_len = (uint8_t)data_ptr[0] << 8 | (uint8_t)data_ptr[1];
     } else if (payload_len == 127) {
         // headerLen += 8;
         header = 8;
-        if ((rlen = esp_transport_read_internal(ws, data_ptr, header, timeout_ms)) <= 0) {
+        if ((rlen = esp_transport_read_blocking(ws, data_ptr, header, timeout_ms)) < header) {
             ESP_LOGE(TAG, "Error read data");
             return rlen;
         }
@@ -523,7 +550,7 @@ static int ws_read_header(esp_transport_handle_t t, char *buffer, int len, int t
 
     if (mask) {
         // Read and store mask
-        if (payload_len != 0 && (rlen = esp_transport_read_internal(ws, buffer, mask_len, timeout_ms)) <= 0) {
+        if (payload_len != 0 && (rlen = esp_transport_read_blocking(ws, buffer, mask_len, timeout_ms)) < mask_len) {
             ESP_LOGE(TAG, "Error read data");
             return rlen;
         }