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feat(ws_transport): add header callback hook (IDFGH-15479) #16119

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feat(ws_transport): add header callback hook (IDFGH-15479) #16119

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7629d08
feat(transport_ws): buffer redir_host separately
bryghtlabs-richard Jun 26, 2025
0245c5c
feat(transport_ws): add header callback hook
bryghtlabs-richard Jun 12, 2025
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29 changes: 29 additions & 0 deletions components/tcp_transport/include/esp_transport_ws.h
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,8 @@ typedef enum ws_transport_opcodes {
* from the API esp_transport_ws_get_read_opcode() */
} ws_transport_opcodes_t;

typedef void (*ws_header_hook)(void * userp, const char * line, int line_len);

/**
* WS transport configuration structure
*/
Expand All @@ -37,6 +39,8 @@ typedef struct {
const char *sub_protocol; /*!< WS subprotocol */
const char *user_agent; /*!< WS user agent */
const char *headers; /*!< WS additional headers */
ws_header_hook header_hook; /*!< WS received header */
void *header_userp; /*!< WS received header user-pointer */
const char *auth; /*!< HTTP authorization header */
char *response_headers; /*!< The buffer to copy the http response header */
size_t response_headers_len; /*!< The length of the http response header */
Expand Down Expand Up @@ -99,6 +103,31 @@ esp_err_t esp_transport_ws_set_user_agent(esp_transport_handle_t t, const char *
*/
esp_err_t esp_transport_ws_set_headers(esp_transport_handle_t t, const char *headers);

/**
* @brief Set websocket header callback
*
* @param t websocket transport handle
* @param hook call function on header received. NULL to disable.
*
* @return
* - ESP_OK on success
* - One of the error codes
*/
esp_err_t esp_transport_ws_set_header_hook(esp_transport_handle_t t, ws_header_hook hook);


/**
* @brief Set websocket header callback user-pointer
*
* @param t websocket transport handle
* @param userp caller-controlled argument to ws_header_hook
*
* @return
* - ESP_OK on success
* - One of the error codes
*/
esp_err_t esp_transport_ws_set_header_userp(esp_transport_handle_t t, void * userp);
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@glmfe glmfe Sep 1, 2025

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Why do we need to set this pointer in a separated function? Could it be a context in the set header hook?

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@bryghtlabs-richard bryghtlabs-richard Sep 1, 2025

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Indeed it could. I'm fine with either way.


/**
* @brief Set websocket authorization headers
*
Expand Down
136 changes: 90 additions & 46 deletions components/tcp_transport/transport_ws.c
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Original file line number Diff line number Diff line change
Expand Up @@ -63,6 +63,8 @@ typedef struct {
char *sub_protocol;
char *user_agent;
char *headers;
ws_header_hook header_hook;
void * header_userp;
char *auth;
char *buffer; /*!< Initial HTTP connection buffer, which may include data beyond the handshake headers, such as the next WebSocket packet*/
size_t buffer_len; /*!< The buffer length */
Expand Down Expand Up @@ -144,31 +146,6 @@ static int esp_transport_read_internal(transport_ws_t *ws, char *buffer, int len
return to_read;
}

static char *trimwhitespace(char *str)
{
char *end;

// Trim leading space
while (isspace((unsigned char)*str)) {
str++;
}

if (*str == 0) {
return str;
}

// Trim trailing space
end = str + strlen(str) - 1;
while (end > str && isspace((unsigned char)*end)) {
end--;
}

// Write new null terminator
*(end + 1) = '\0';

return str;
}

static int get_http_status_code(const char *buffer)
{
const char http[] = "HTTP/";
Expand All @@ -189,26 +166,14 @@ static int get_http_status_code(const char *buffer)
return -1;
}

static char *get_http_header(char *buffer, const char *key)
{
char *found = strcasestr(buffer, key);
if (found) {
found += strlen(key);
char *found_end = strstr(found, "\r\n");
if (found_end) {
*found_end = '\0'; // terminal string

return trimwhitespace(found);
}
}
return NULL;
}

static int ws_connect(esp_transport_handle_t t, const char *host, int port, int timeout_ms)
{
transport_ws_t *ws = esp_transport_get_context_data(t);
const char delimiter[] = "\r\n\r\n";

free(ws->redir_host);
ws->redir_host = NULL;

if (esp_transport_connect(ws->parent, host, port, timeout_ms) < 0) {
ESP_LOGE(TAG, "Error connecting to host %s:%d", host, port);
return -1;
Expand Down Expand Up @@ -327,16 +292,67 @@ static int ws_connect(esp_transport_handle_t t, const char *host, int port, int
if (ws->http_status_code == -1) {
ESP_LOGE(TAG, "HTTP upgrade failed");
return -1;
} else if (WS_HTTP_TEMPORARY_REDIRECT(ws->http_status_code) || WS_HTTP_PERMANENT_REDIRECT(ws->http_status_code)) {
ws->redir_host = get_http_header(ws->buffer, "Location:");
if (ws->redir_host == NULL) {
}

const char *location = NULL;
int location_len = 0;

const char *server_key = NULL;
int server_key_len = 0;
const char * header_cursor = strnstr(ws->buffer, "\r\n", header_len);
if (!header_cursor){
ESP_LOGE(TAG, "HTTP Header locate failed");
return -1;
}
header_cursor += strlen("\r\n");

while(header_cursor < delim_ptr){
const char * end_of_line = strnstr(header_cursor, "\r\n", header_len - (header_cursor - ws->buffer));
if(!end_of_line){
ESP_LOGE(TAG, "HTTP Header walk failed");
return -1;
}
else if(end_of_line == header_cursor){
ESP_LOGD(TAG, "HTTP Header walk found end");
break;
}
int line_len = end_of_line - header_cursor;
ESP_LOGD(TAG, "HTTP Header walk line:%.*s", line_len, header_cursor);

// Check for Sec-WebSocket-Accept header
const char * header_sec_websocket_accept = "Sec-WebSocket-Accept: ";
size_t header_sec_websocket_accept_len = strlen(header_sec_websocket_accept);
if (line_len >= header_sec_websocket_accept_len && !strncasecmp(header_cursor, header_sec_websocket_accept, header_sec_websocket_accept_len)) {
ESP_LOGD(TAG, "found server-key");
server_key = header_cursor + header_sec_websocket_accept_len;
server_key_len = line_len - header_sec_websocket_accept_len;
}
else if (ws->header_hook) {
ws->header_hook(ws->header_userp, header_cursor, line_len);
}

// Check for Location: header
const char * header_location = "Location: ";
size_t header_location_len = strlen(header_location);
if (line_len >= header_location_len && !strncasecmp(header_cursor, header_location, header_location_len)) {
location = header_cursor + header_location_len;
location_len = line_len - header_location_len;
}

// Adjust cursor to the start of the next line
header_cursor += line_len;
header_cursor += strlen("\r\n");
}

if (WS_HTTP_TEMPORARY_REDIRECT(ws->http_status_code) || WS_HTTP_PERMANENT_REDIRECT(ws->http_status_code)) {
if (location == NULL || location_len <= 0) {
ESP_LOGE(TAG, "Location header not found");
return -1;
}
ws->redir_host = strndup(location, location_len);
return ws->http_status_code;
}

char *server_key = get_http_header(ws->buffer, "Sec-WebSocket-Accept:");
if (server_key == NULL) {
ESP_LOGE(TAG, "Sec-WebSocket-Accept not found");
return -1;
Expand All @@ -357,7 +373,7 @@ static int ws_connect(esp_transport_handle_t t, const char *host, int port, int
esp_crypto_base64_encode(expected_server_key, sizeof(expected_server_key), &outlen, expected_server_sha1, sizeof(expected_server_sha1));
expected_server_key[ (outlen < sizeof(expected_server_key)) ? outlen : (sizeof(expected_server_key) - 1) ] = 0;
ESP_LOGD(TAG, "server key=%s, send_key=%s, expected_server_key=%s", (char *)server_key, (char *)client_key, expected_server_key);
if (strcmp((char *)expected_server_key, (char *)server_key) != 0) {
if (strncmp((char *)expected_server_key, (char *)server_key, server_key_len) != 0) {
ESP_LOGE(TAG, "Invalid websocket key");
return -1;
}
Expand All @@ -371,7 +387,6 @@ static int ws_connect(esp_transport_handle_t t, const char *host, int port, int
} else {
#ifdef CONFIG_WS_DYNAMIC_BUFFER
free(ws->buffer);
ws->redir_host = NULL;
ws->buffer = NULL;
#endif
ws->buffer_len = 0;
Expand Down Expand Up @@ -713,6 +728,7 @@ static esp_err_t ws_destroy(esp_transport_handle_t t)
{
transport_ws_t *ws = esp_transport_get_context_data(t);
free(ws->buffer);
free(ws->redir_host);
free(ws->path);
free(ws->sub_protocol);
free(ws->user_agent);
Expand Down Expand Up @@ -862,6 +878,26 @@ esp_err_t esp_transport_ws_set_headers(esp_transport_handle_t t, const char *hea
return ESP_OK;
}

esp_err_t esp_transport_ws_set_header_hook(esp_transport_handle_t t, ws_header_hook hook)
{
if (t == NULL) {
return ESP_ERR_INVALID_ARG;
}
transport_ws_t *ws = esp_transport_get_context_data(t);
ws->header_hook = hook;
return ESP_OK;
}

esp_err_t esp_transport_ws_set_header_userp(esp_transport_handle_t t, void * userp)
{
if (t == NULL) {
return ESP_ERR_INVALID_ARG;
}
transport_ws_t *ws = esp_transport_get_context_data(t);
ws->header_userp = userp;
return ESP_OK;
}

esp_err_t esp_transport_ws_set_auth(esp_transport_handle_t t, const char *auth)
{
if (t == NULL) {
Expand Down Expand Up @@ -927,6 +963,14 @@ esp_err_t esp_transport_ws_set_config(esp_transport_handle_t t, const esp_transp
err = esp_transport_ws_set_headers(t, config->headers);
ESP_TRANSPORT_ERR_OK_CHECK(TAG, err, return err;)
}
if (config->header_hook) {
err = esp_transport_ws_set_header_hook(t, config->header_hook);
ESP_TRANSPORT_ERR_OK_CHECK(TAG, err, return err;)
}
if (config->header_userp) {
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@glmfe glmfe Sep 1, 2025

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What if user set this, but the hook isn't configured, should we warn? Is the idea that the context for the callback could change in between calls?

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@bryghtlabs-richard bryghtlabs-richard Sep 1, 2025

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I'm not sure I would worry about it, but if it's preferred we could. I don't expect anyone would change the header_userp context in-between headers, given that their ordering isn't guaranteed.

err = esp_transport_ws_set_header_userp(t, config->header_userp);
ESP_TRANSPORT_ERR_OK_CHECK(TAG, err, return err;)
}
if (config->auth) {
err = esp_transport_ws_set_auth(t, config->auth);
ESP_TRANSPORT_ERR_OK_CHECK(TAG, err, return err;)
Expand Down