romenskiy2012/curl

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Jay Satiro 6c70ec16c7 http: ignore invalid Retry-After times

- Treat negative Retry-After date-based times as 0.

- Treat Retry-After times greater than 6 hours as 6 hours.

Prior to this change Retry-After did not have a limited range and the
server could have set a time greater than 6 hours or a date in the past
that would result in a negative time, either of which may be unexpected
by the user.

The 6 hour limit is purposely not documented so that it can be changed
in the future if necessary.

Closes https://github.com/curl/curl/pull/15833

2024-12-31 03:19:22 -05:00

1.7 KiB

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SPDX-License-Identifier

Title

Section

Source

See-also

Protocol

Added-in

curl

CURLINFO_RETRY_AFTER

libcurl

CURLOPT_HEADERFUNCTION (3)

CURLOPT_STDERR (3)

curl_easy_header (3)

All

7.66.0

NAME

CURLINFO_RETRY_AFTER - returns the Retry-After retry delay

SYNOPSIS

#include <curl/curl.h>

CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_RETRY_AFTER,
                           curl_off_t *retry);

DESCRIPTION

Pass a pointer to a curl_off_t variable to receive the number of seconds the HTTP server suggests the client should wait until the next request is issued. The information from the "Retry-After:" header.

While the HTTP header might contain a fixed date string, the CURLINFO_RETRY_AFTER(3) always returns the number of seconds to wait - or zero if there was no header or the header could not be parsed.

This option used to return a negative wait time if the server provided a date in the past. Since 8.12.0, a negative wait time is returned as zero. In any case we recommend checking that the wait time is within an acceptable range for your circumstance.

DEFAULT

Zero if there was no header.

%PROTOCOLS%

EXAMPLE

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
    res = curl_easy_perform(curl);
    if(res == CURLE_OK) {
      curl_off_t wait = 0;
      curl_easy_getinfo(curl, CURLINFO_RETRY_AFTER, &wait);
      if(wait)
        printf("Wait for %" CURL_FORMAT_CURL_OFF_T " seconds\n", wait);
    }
    curl_easy_cleanup(curl);
  }
}

%AVAILABILITY%

RETURN VALUE

Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.

1.7 KiB Raw Blame History