From 46bacc35e7e32083857b851ad34ed8ae651c23ce Mon Sep 17 00:00:00 2001
From: Richard Allen <richard@bryghtlabs.com>
Date: Thu, 10 Oct 2024 17:31:21 -0500
Subject: [PATCH] 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 | 36 ++++++++++++++++++++++---
 1 file changed, 32 insertions(+), 4 deletions(-)

diff --git a/components/tcp_transport/transport_ws.c b/components/tcp_transport/transport_ws.c
index 0211347fba03..6d715590b40d 100644
--- a/components/tcp_transport/transport_ws.c
+++ b/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)) < header) {
         ESP_LOGE(TAG, "Error read data");
         return rlen;
     }
@@ -500,7 +528,7 @@ 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)) < header) {
             ESP_LOGE(TAG, "Error read data");
             return rlen;
         }
@@ -508,7 +536,7 @@ static int ws_read_header(esp_transport_handle_t t, char *buffer, int len, int t
     } 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)) < header) {
             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)) < mask_len) {
             ESP_LOGE(TAG, "Error read data");
             return rlen;
         }