ESP HTTP Client: disable_auto_redirect causes infinite loop (IDFGH-9243)

[jgillick]

Answers checklist.

• I have read the documentation ESP-IDF Programming Guide and the issue is not addressed there.
• I have updated my IDF branch (master or release) to the latest version and checked that the issue is present there.
• I have searched the issue tracker for a similar issue and not found a similar issue.

IDF version.

v5.0

Operating System used.

macOS

How did you build your project?

Command line with idf.py

If you are using Windows, please specify command line type.

None

Development Kit.

XIAO_ESP32C3

Power Supply used.

USB

What is the expected behavior?

When using .disable_auto_redirect = true, I'd expect the HTTP request to end when it get's to a redirect. At that point, the firmware can manually get the location header and decide what to do with the redirect or handle it in the event handler.

esp_http_client_config_t config = {
    .url = "http://httpbin.org/absolute-redirect/3",
    .event_handler = _http_event_handler,
    .disable_auto_redirect = true,
};

What is the actual behavior?

The HTTP client goes into an infinite loop until redirect_counter reaches the maximum count.

This is caused by the following lines of code:

if (client->disable_auto_redirect) {
    http_dispatch_event(client, HTTP_EVENT_REDIRECT, NULL, 0);
} else {
    ESP_ERROR_CHECK(esp_http_client_set_redirection(client));
}
client->redirect_counter ++;
client->process_again = 1;

The block of code prevents the redirect from happening, but then sets process_again to 1, which causes the response to be processed again.

I believe the solution should be to put the redirect_counter and process_again assignments in the else statement.

if (client->disable_auto_redirect) {
    ESP_LOGI(TAG, "REDIRECT!");
    http_dispatch_event(client, HTTP_EVENT_REDIRECT, NULL, 0);
} else {
    ESP_ERROR_CHECK(esp_http_client_set_redirection(client));
    client->redirect_counter ++;
    client->process_again = 1;
}

Steps to reproduce.

1. Create a simple HTTP client that points to a URL with a redirect and set disable_auto_redirect to false.
2. Do NOT handle the redirect in the event handler
3. Run the program, and observe that the request hits the maximum redirects error and fails.

Debug Logs.

No response

More Information.

No response

[AxelLin]

master: 5feb469
v5.0: 9463a66

[Harshal5]

Hello @jgillick ,
Sorry for the delayed response.

The HTTP client goes into an infinite loop until redirect_counter reaches the maximum count.

Thank you for reporting this issue. Rather than putting the redirect_counter and process_again assignments in the else statement, we should add them in the esp_http_client_set_redirection function, because it will also handle the case when disable_auto_redirect = true and the user calls esp_http_client_set_redirection in the event handler.

Attached is the patch for same. Could you please check if it satisfies your requirement?
0001-http_client-fixed-looping-caused-when-disable_auto_r.patch

[jgillick]

@Harshal5 I haven't had a chance to try this patch directly, but the change makes sense and looks good.