How to Fix Zero Content Length in cURL HTTPS Connections: Certificate Authentication Issues?

HTTPS Site Connection Issue with cURL: Fixing Zero Content Length

When attempting to connect to an HTTPS site using cURL, you may encounter an issue where the response content length is zero. This problem often arises due to certificate authentication issues. Here are the steps you can take to resolve this:

1. Update cURL Certificate File:

cURL utilizes an outdated file for HTTPS certificate authentication. You can obtain the latest version from:

http://curl.haxx.se/ca/cacert.pem

Save the file in a directory on your server.

2. Configure cURL to Use the New Certificate File:

In your cURL configuration, add the following line:

curl_setopt ($curl_ch, CURLOPT_CAINFO, dirname(__FILE__)."/cacert.pem");

This specifies that cURL should use the new certificate file for authentication.

3. Alternative Solution:

Alternatively, you can configure php.ini to use the system-wide CA certificate bundle:

curl.cainfo=/etc/ssl/certs/ca-certificates.crt

4. Avoid Disabling Verification:

It's crucial to avoid disabling CURLOPT_VERIFYPEER and CURLOPT_VERIFYHOST as they protect against man-in-the-middle attacks.

5. Use Composer Package:

For a more comprehensive solution, consider using the paragonie/certainty composer package, which manages CA certificates and ensures their validity:

composer require paragonie/certainty:dev-master

By implementing these measures, you can ensure that cURL successfully authenticates HTTPS certificates and retrieves the correct content from the secure gateway.

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