基于Matt's Script Archive FormMail.cgi的reCAPTCHA V2验证失败求助

Let's dig into why your reCAPTCHA V2 verification keeps failing. The biggest issue with your current code is that you're using a regex to match the JSON response—and JSON doesn't guarantee consistent whitespace or key order. For example, "success": true might show up as "success":true or come after other keys in the response, breaking your regex check entirely.

Here's how to fix this properly using reliable JSON parsing:

Step 1: Use a JSON Parser #

Perl includes core modules like JSON::PP (no extra installation needed for Perl 5.14+) that let you safely parse API responses instead of relying on flaky regex matches.

Step 2: Updated Verification Code #

Replace your check_captcha subroutine with this version:

sub check_captcha {
    my $ua = LWP::UserAgent->new();
    # Ensure HTTPS requests work (install LWP::Protocol::https if you get connection errors)
    $ua->ssl_opts( verify_hostname => 1 );

    my $result = $ua->post(
        'https://www.google.com/recaptcha/api/siteverify',
        {
            secret   => 'MyPrivateKey', # Confirm this is your reCAPTCHA V2 secret key (not V1!)
            remoteip => $ENV{'REMOTE_ADDR'},
            response => $Form{'g-recaptcha-response'}
        }
    );

    # First handle HTTP request failures (e.g., network issues)
    if (!$result->is_success) {
        &error('captcha_connection_failed');
        return;
    }

    # Parse the JSON response safely
    my $json = JSON::PP->new();
    my $response_data;
    eval {
        $response_data = $json->decode($result->content);
    };
    if ($@) {
        &error('captcha_invalid_response');
        return;
    }

    # Check the success flag the right way
    if ($response_data->{success}) {
        return; # Verification passed
    } else {
        # Optional: Log error codes for debugging (e.g., invalid secret, missing response)
        my $error_codes = join(', ', @{$response_data->{'error-codes'} || []});
        warn "reCAPTCHA failed with errors: $error_codes";
        &error('captcha_failed');
    }
}

Additional Troubleshooting Tips #

• Double-check your secret key: Make sure you're using the reCAPTCHA V2 secret key (not the old V1 private key, and not the public site key).
• Verify the g-recaptcha-response value: Add a debug line like warn "Captcha response: " . $Form{'g-recaptcha-response'}; to confirm the frontend is sending this parameter correctly to your CGI script.
• HTTPS support: If you get errors connecting to the siteverify URL, install the LWP::Protocol::https module via CPAN to enable HTTPS for LWP.
• Use error codes: The API returns specific error codes when verification fails (like invalid-input-secret or missing-input-response). The code above logs these, which will help you pinpoint exactly what's going wrong.

内容的提问来源于stack exchange，提问作者Lee Mac