Add Input Validation for Host and Port in C-Based Stager Client

[CyberForgeEx]

This PR addresses the lack of input validation for command-line arguments in the C-based Metasploit stager client, which could cause crashes or undefined behavior when invalid inputs (e.g., null, empty, or non-numeric port) are provided. The changes improve robustness by ensuring argv[1] (host) and argv[2] (port) are valid before use.

Please review and let me know if additional changes or tests are needed!