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Merge branch 'contrib/github_pr_18684' into 'master'

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feat(httpd): avoid useless string copy by introducing httpd_req_get_url_query_str_ptr() (GitHub PR)

Closes IDFGH-17758

See merge request espressif/esp-idf!49682
This commit is contained in:
Mahavir Jain
2026-06-30 18:15:48 +05:30
parent 9bd49630fc 594cc4a5ad
commit cb33ab16b3
3 changed files with 321 additions and 95 deletions
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219
components/esp_http_server/src/httpd_parse.c
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@@ -1032,6 +1032,92 @@ esp_err_t httpd_req_get_url_query_str(httpd_req_t *r, char *buf, size_t buf_len)
return ESP_ERR_NOT_FOUND;
}
esp_err_t httpd_req_get_url_query_str_ptr(httpd_req_t *r, const char **buf, size_t *buf_len)
{
/* buf_len is an output pointer that is dereferenced below, so it must be
* validated along with the other arguments to avoid a NULL write */
if (r == NULL || buf == NULL || buf_len == NULL) {
return ESP_ERR_INVALID_ARG;
}
if (!httpd_valid_req(r)) {
return ESP_ERR_HTTPD_INVALID_REQ;
}
if (r->uri[0] == '\0') {
ESP_LOGD(TAG, "uri is empty");
return ESP_FAIL;
}
struct httpd_req_aux *ra = r->aux;
struct http_parser_url *res = &ra->url_parse_res;
/* Check if query field is present in the URL */
if (res->field_set & (1 << UF_QUERY)) {
*buf = r->uri + res->field_data[UF_QUERY].off;
/* Query data length does not include terminating null */
*buf_len = res->field_data[UF_QUERY].len;
return ESP_OK;
}
return ESP_ERR_NOT_FOUND;
}
/* Advance the scratch pointer past the current header line to the next one.
* Header lines are separated by null characters (their line terminators are
* overwritten with '\0' during parsing). */
static const char *httpd_next_hdr(const char *hdr_ptr)
{
/* Jump to the end of the current field-value string */
hdr_ptr = 1 + strchr(hdr_ptr, '\0');
/* Skip all null characters with which the line terminators were overwritten */
while (*hdr_ptr == '\0') {
hdr_ptr++;
}
return hdr_ptr;
}
/* Locate the value of a header field within the request's scratch buffer.
* Returns a pointer to the NULL-terminated value (leading spaces skipped),
* or NULL if the field is not present. The caller must validate r/field and
* the request pointer before calling. */
static const char *httpd_find_hdr_value(struct httpd_req_aux *ra, const char *field)
{
const char *hdr_ptr = ra->scratch; /*!< Request headers are kept in scratch buffer */
unsigned count = ra->req_hdrs_count; /*!< Count set during parsing */
const size_t field_len = strlen(field);
while (count--) {
/* Search for the ':' character. Else, it would mean
* that the field is invalid */
const char *val_ptr = strchr(hdr_ptr, ':');
if (!val_ptr) {
break;
}
/* If the field does not match, continue searching. Compare lengths
* first as the field from the header is not null terminated (has ':'
* in the end). */
if (((size_t)(val_ptr - hdr_ptr) != field_len) ||
strncasecmp(hdr_ptr, field, field_len)) {
if (count) {
hdr_ptr = httpd_next_hdr(hdr_ptr);
}
continue;
}
/* Skip ':' and any preceding spaces */
val_ptr++;
while (*val_ptr == ' ') {
val_ptr++;
}
return val_ptr;
}
return NULL;
}
/* Get the length of the value string of a header request field */
size_t httpd_req_get_hdr_value_len(httpd_req_t *r, const char *field)
{
@@ -1043,48 +1129,8 @@ size_t httpd_req_get_hdr_value_len(httpd_req_t *r, const char *field)
return 0;
}
struct httpd_req_aux *ra = r->aux;
const char *hdr_ptr = ra->scratch; /*!< Request headers are kept in scratch buffer */
unsigned count = ra->req_hdrs_count; /*!< Count set during parsing */
while (count--) {
/* Search for the ':' character. Else, it would mean
* that the field is invalid
*/
const char *val_ptr = strchr(hdr_ptr, ':');
if (!val_ptr) {
break;
}
/* If the field, does not match, continue searching.
* Compare lengths first as field from header is not
* null terminated (has ':' in the end).
*/
if ((val_ptr - hdr_ptr != strlen(field)) ||
(strncasecmp(hdr_ptr, field, strlen(field)))) {
if (count) {
/* Jump to end of header field-value string */
hdr_ptr = 1 + strchr(hdr_ptr, '\0');
/* Skip all null characters (with which the line
* terminators had been overwritten) */
while (*hdr_ptr == '\0') {
hdr_ptr++;
}
}
continue;
}
/* Skip ':' */
val_ptr++;
/* Skip preceding space */
while ((*val_ptr != '\0') && (*val_ptr == ' ')) {
val_ptr++;
}
return strlen(val_ptr);
}
return 0;
const char *val_ptr = httpd_find_hdr_value(r->aux, field);
return val_ptr ? strlen(val_ptr) : 0;
}
/* Get the value of a field from the request headers */
@@ -1098,58 +1144,45 @@ esp_err_t httpd_req_get_hdr_value_str(httpd_req_t *r, const char *field, char *v
return ESP_ERR_HTTPD_INVALID_REQ;
}
struct httpd_req_aux *ra = r->aux;
const char *hdr_ptr = ra->scratch; /*!< Request headers are kept in scratch buffer */
unsigned count = ra->req_hdrs_count; /*!< Count set during parsing */
while (count--) {
/* Search for the ':' character. Else, it would mean
* that the field is invalid
*/
const char *val_ptr = strchr(hdr_ptr, ':');
if (!val_ptr) {
break;
}
/* If the field, does not match, continue searching.
* Compare lengths first as field from header is not
* null terminated (has ':' in the end).
*/
if ((val_ptr - hdr_ptr != strlen(field)) ||
(strncasecmp(hdr_ptr, field, strlen(field)))) {
if (count) {
/* Jump to end of header field-value string */
hdr_ptr = 1 + strchr(hdr_ptr, '\0');
/* Skip all null characters (with which the line
* terminators had been overwritten) */
while (*hdr_ptr == '\0') {
hdr_ptr++;
}
}
continue;
}
/* Skip ':' */
val_ptr++;
/* Skip preceding space */
while ((*val_ptr != '\0') && (*val_ptr == ' ')) {
val_ptr++;
}
/* Get the NULL terminated value and copy it to the caller's buffer.
* Note `strlcpy()` will always return the size of the source string
* including terminimating null.*/
size_t full_size = strlcpy(val, val_ptr, val_size);
/* If buffer length is smaller than needed, return truncation error */
if (val_size < full_size) {
return ESP_ERR_HTTPD_RESULT_TRUNC;
}
return ESP_OK;
const char *val_ptr = httpd_find_hdr_value(r->aux, field);
if (val_ptr == NULL) {
return ESP_ERR_NOT_FOUND;
}
return ESP_ERR_NOT_FOUND;
/* Get the NULL terminated value and copy it to the caller's buffer.
* Note `strlcpy()` will always return the size of the source string
* including terminating null. */
size_t full_size = strlcpy(val, val_ptr, val_size);
/* If buffer length is smaller than needed, return truncation error */
if (val_size < full_size) {
return ESP_ERR_HTTPD_RESULT_TRUNC;
}
return ESP_OK;
}
esp_err_t httpd_req_get_hdr_value_str_ptr(httpd_req_t *r, const char *field, const char **val, size_t *val_len)
{
/* val and val_len are output pointers that are dereferenced below, so they
* must be validated along with the other arguments to avoid a NULL write */
if (r == NULL || field == NULL || val == NULL || val_len == NULL) {
return ESP_ERR_INVALID_ARG;
}
if (!httpd_valid_req(r)) {
return ESP_ERR_HTTPD_INVALID_REQ;
}
const char *val_ptr = httpd_find_hdr_value(r->aux, field);
if (val_ptr == NULL) {
return ESP_ERR_NOT_FOUND;
}
/* The value lives NULL-terminated in the request scratch buffer; return a
* pointer to it instead of copying. Valid only within the URI handler. */
*val = val_ptr;
*val_len = strlen(val_ptr);
return ESP_OK;
}
/* Helper function to get a cookie value from a cookie string of the type "cookie1=val1; cookie2=val2" */