feat(transport_ws): add support for per-message compression handshakes

Author: huming2207

components/tcp_transport/include/esp_transport_ws.h

@@ -24,6 +24,7 @@ typedef enum ws_transport_opcodes {
     WS_TRANSPORT_OPCODES_CLOSE = 0x08,
     WS_TRANSPORT_OPCODES_PING = 0x09,
     WS_TRANSPORT_OPCODES_PONG = 0x0a,
+    WS_TRANSPORT_OPCODES_COMPRESSED = 0x40,
     WS_TRANSPORT_OPCODES_FIN = 0x80,
     WS_TRANSPORT_OPCODES_NONE = 0x100,   /*!< not a valid opcode to indicate no message previously received
                                           * from the API esp_transport_ws_get_read_opcode() */
@@ -48,6 +49,13 @@ typedef struct {
                                              *   If false, only user frames are propagated, control frames are handled
                                              *   automatically during read operations
                                              */
+    bool per_msg_compress;                  /*!< Hint the server to enable per-message compression (RFC7692) */
+    int per_msg_client_deflate_window_bit;  /*!< Hint the server Per-message deflate window bit 8 to 15; or leave 0 to let server decide */
+    int per_msg_server_deflate_window_bit;  /*!< Hint the server Per-message deflate window bit 8 to 15; or leave 0 to let server decide */
+    bool per_msg_server_no_ctx_takeover;    /*!< Hint the server to reset the compression stream on every WS frame on server side
+                                             *   True for a safer transfer, false for better performance */
+    bool per_msg_client_no_ctx_takeover;    /*!< Hint the server to reset the compression stream on every WS frame on client side
+                                             *   True for a safer transfer, false for better performance */
 } esp_transport_ws_config_t;
 
 /**

components/tcp_transport/transport_ws.c

@@ -24,6 +24,7 @@ static const char *TAG = "transport_ws";
 
 #define WS_BUFFER_SIZE              CONFIG_WS_BUFFER_SIZE
 #define WS_FIN                      0x80
+#define WS_COMPRESSED               0x40
 #define WS_OPCODE_CONT              0x00
 #define WS_OPCODE_TEXT              0x01
 #define WS_OPCODE_BINARY            0x02
@@ -56,6 +57,7 @@ typedef struct {
     int payload_len;                    /*!< Total length of the payload */
     int bytes_remaining;                /*!< Bytes left to read of the payload  */
     bool header_received;               /*!< Flag to indicate that a new message header was received */
+    bool compressed;                    /*!< Per-message deflate compress flag (RSV1) */
 } ws_transport_frame_state_t;
 
 typedef struct {
@@ -75,6 +77,11 @@ typedef struct {
     char *redir_host;
     char *response_header;
     size_t response_header_len;
+    bool per_msg_compress;
+    int per_msg_client_deflate_window_bit;
+    int per_msg_server_deflate_window_bit;
+    bool per_msg_server_no_ctx_takeover;
+    bool per_msg_client_no_ctx_takeover;
 } transport_ws_t;
 
 /**
@@ -201,6 +208,20 @@ static int ws_connect(esp_transport_handle_t t, const char *host, int port, int
 #endif
 
     size_t outlen = 0;
+    char extension_header[160] = { 0 };
+    if (ws->per_msg_compress) {
+        if (ws->per_msg_client_deflate_window_bit != 0) {
+
+        }
+
+        int ext_len = snprintf(extension_header,
+                               sizeof(extension_header),
+                               "Sec-WebSocket-Extensions: permessage-deflate;%s%s%s%s",
+                               ws->per_msg_client_no_ctx_takeover ? " client_no_context_takeover; " : "",
+                               ws->per_msg_server_no_ctx_takeover ? " server_no_context_takeover; " : "",
+        );
+    }
+
     esp_crypto_base64_encode(client_key, sizeof(client_key), &outlen, random_key, sizeof(random_key));
     int len = snprintf(ws->buffer, WS_BUFFER_SIZE,
                        "GET %s HTTP/1.1\r\n"
@@ -209,7 +230,8 @@ static int ws_connect(esp_transport_handle_t t, const char *host, int port, int
                        "User-Agent: %s\r\n"
                        "Upgrade: websocket\r\n"
                        "Sec-WebSocket-Version: 13\r\n"
-                       "Sec-WebSocket-Key: %s\r\n",
+                       "Sec-WebSocket-Key: %s\r\n"
+                       "%s", // For "Sec-WebSocket-Extensions"
                        ws->path,
                        host, port, user_agent_ptr,
                        client_key);
@@ -575,6 +597,7 @@ static int ws_read_header(esp_transport_handle_t t, char *buffer, int len, int t
     ws->frame_state.header_received = true;
     ws->frame_state.fin = (*data_ptr & 0x80) != 0;
     ws->frame_state.opcode = (*data_ptr & 0x0F);
+    ws->frame_state.compressed = (*data_ptr & 0x40) != 0; // RSV1 bit in the header
     data_ptr ++;
     mask = ((*data_ptr >> 7) & 0x01);
     payload_len = (*data_ptr & 0x7F);
@@ -979,6 +1002,21 @@ esp_err_t esp_transport_ws_set_config(esp_transport_handle_t t, const esp_transp
     }
 
     ws->propagate_control_frames = config->propagate_control_frames;
+    ws->per_msg_compress = config->per_msg_compress;
+    ws->per_msg_client_no_ctx_takeover = config->per_msg_client_no_ctx_takeover;
+    ws->per_msg_server_no_ctx_takeover = config->per_msg_server_no_ctx_takeover;
+
+    if (config->per_msg_client_deflate_window_bit < 8 || config->per_msg_client_deflate_window_bit > 15) {
+        ws->per_msg_client_deflate_window_bit = 0;
+    } else {
+        ws->per_msg_client_deflate_window_bit = config->per_msg_client_deflate_window_bit;
+    }
+
+    if (config->per_msg_server_deflate_window_bit < 8 || config->per_msg_server_deflate_window_bit > 15) {
+        ws->per_msg_server_deflate_window_bit = 0;
+    } else {
+        ws->per_msg_server_deflate_window_bit = config->per_msg_server_deflate_window_bit;
+    }
 
     return err;
 }