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 +133,34 @@ static int esp_transport_read_internal(transport_ws_t *ws, char *buffer, int len
     return to_read;
 }
 
+static int esp_transport_read_exact_size(transport_ws_t *ws, char *buffer, int requested_len, int timeout_ms)
+{
+    int total_read = 0;
+    int len = requested_len;
+
+    while (len > 0) {
+        int bytes_read = esp_transport_read_internal(ws, buffer, len, timeout_ms);
+
+        if (bytes_read < 0) {
+            return bytes_read; // Return error from the underlying read
+        }
+
+        if (bytes_read == 0) {
+            // If we read 0 bytes, we return an error, since reading exact number of bytes resulted in a timeout operation
+            ESP_LOGW(TAG, "Requested to read %d, actually read %d bytes", requested_len, total_read);
+            return -1;
+        }
+
+        // Update buffer and remaining length
+        buffer += bytes_read;
+        len -= bytes_read;
+        total_read += bytes_read;
+
+        ESP_LOGV(TAG, "Read fragment of %d bytes", bytes_read);
+    }
+    return total_read;
+}
+
 static char *trimwhitespace(char *str)
 {
     char *end;
@@ -486,7 +514,7 @@ 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_exact_size(ws, data_ptr, header, timeout_ms)) <= 0) {
         ESP_LOGE(TAG, "Error read data");
         return rlen;
     }
@@ -500,15 +528,15 @@ 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_exact_size(ws, data_ptr, header, timeout_ms)) <= 0) {
             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_exact_size(ws, data_ptr, header, timeout_ms)) <= 0) {
             ESP_LOGE(TAG, "Error read data");
             return rlen;
         }
@@ -523,7 +551,7 @@ 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_exact_size(ws, buffer, mask_len, timeout_ms)) <= 0) {
             ESP_LOGE(TAG, "Error read data");
             return rlen;
         }