Registering a remote MCP server (sse/streamable-http) whose hostname
resolves to a private IP is rejected at config-validation time by the
SSRF guard, with no production escape hatch -- the only bypass is a
test-only loopback flag. Self-hosted MCP servers on a private network
are therefore unregisterable, even though the runtime MCP client
connects to them fine (Test Connection succeeds and lists tools; only
create/update input validation blocks).
Add an opt-in, operator-configured allowlist (GOCLAW_MCP_ALLOWED_HOSTS,
empty by default) of trusted hostnames exempt from the private/loopback
IP block during MCP server URL validation only:
- security.ValidateAllowingHosts(url, allowedHosts): like Validate but
skips the private/loopback block for allowlisted hostnames. The
cloud-metadata/link-local (169.254/fe80), multicast and unspecified
ranges are never exempted, even for allowlisted hosts.
- mcp.SetAllowedHosts wires the operator allowlist into ValidateURL /
ValidateServerConfig; default empty => no behavior change.
- web_fetch / webhook / redirect SSRF paths are unchanged (those stay
agent-influenced and fully guarded).
Matching is case-insensitive on the pre-resolution hostname.
