fix(syslog): Prevent Syslog TCP SSRF - #3816
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Syslog TCP/TLS connections now resolve configured hosts at connection time with
SSRF.safe_resolve_all/1, validate every address from one DNS result, and retry the pinned IPs sequentially, preventing DNS rebinding and internal port probing without losing OTP's hostname fallback behavior.TLS still uses the original hostname for SNI and certificate verification, while explicitly configured single-tenant deployments retain private-network access.
safe_resolve/1preserves its first-address contract for existing webhook/Finch consumers, and focused tests cover rejection, full-answer validation, address fallback, IP pinning, TLS identity, and the single-tenant exception.Validated with 27 Syslog tests, 14 SSRF utility tests, targeted Credo, formatting, and diff checks.