Refactor code for PHP 8.4 compatibility

[devin-ai-integration]

Refactor code for PHP 8.4 compatibility

Summary

Fixed the main PHP 8.4 compatibility issue by adding explicit nullable type declarations to method parameters that previously used implicit nullable syntax (deprecated in PHP 8.4).

Changes made:

• Updated PhpSIP::__construct() to use ?string $src_ip = null, ?int $src_port = null, ?int $fr_timer = null
• Updated PhpSIP::setContentType() to use ?string $content_type = null
• Updated PhpSIP::setCallId() to use ?string $v = null

Validation completed:

• ✅ Syntax validation with PHP 8.4.10 - no errors detected
• ✅ Automated search found and fixed all instances of implicitly nullable parameters
• ⚠️ Limited functional testing due to network requirements

Review & Testing Checklist for Human

• Verify type declarations are semantically correct - Confirm that IP addresses should be strings, ports/timers should be integers
• Test with actual SIP infrastructure - Run examples against real SIP servers to ensure functionality isn't broken
• Check for other PHP 8.4 compatibility issues - Review for any other deprecated features I may have missed
• Validate backward compatibility - Ensure existing code using this library still works without modifications

Recommended test plan: Run your existing SIP test suite or example scripts against a real SIP server with PHP 8.4 to verify end-to-end functionality.

---

Diagram

%%{ init : { "theme" : "default" }}%%
graph TD
    Examples["examples/*.php<br/>(message.php, options.php, etc)"]:::context
    Main["PhpSIP.class.php<br/>(Main SIP library)"]:::major-edit
    Exception["PhpSIP.Exception.php<br/>(Exception class)"]:::context
    
    Examples -->|"require_once"| Main
    Main -->|"throws"| Exception
    
    Main -->|"Updated constructor<br/>and method signatures"| TypeHints["Explicit nullable types<br/>?string, ?int"]:::major-edit
    
    subgraph Legend
        L1["Major Edit"]:::major-edit
        L2["Minor Edit"]:::minor-edit  
        L3["Context/No Edit"]:::context
    end

classDef major-edit fill:#90EE90
classDef minor-edit fill:#87CEEB
classDef context fill:#FFFFFF

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Notes

• This addresses the main PHP 8.4 deprecation affecting this codebase (implicitly nullable parameters)
• Socket functions and regex patterns used in the library remain compatible with PHP 8.4
• Link to Devin run: https://app.devin.ai/sessions/765f7395244241abbbdf2dc2516f7015
• Requested by: @l7s

[devin-ai-integration]

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