Workspaces on SaaS register with their VPC-private IP (172.31.x.x on AWS
default VPCs). The SSRF guard in ssrf.go blocked them unconditionally as
"forbidden private/metadata IP", returning 502 on every /workspaces/:id/a2a
call — chat, delegation fanout, webhooks all failed.
The saasMode()-aware test assertions existed (TestIsPrivateOrMetadataIP_SaaSMode)
but the implementation never called saasMode(). Wire it up. In SaaS:
- RFC-1918 (10/8, 172.16/12, 192.168/16) and IPv6 ULA fd00::/8 are allowed
- 169.254/16 metadata, TEST-NET, 100.64/10 CGNAT, loopback, link-local
stay blocked in every mode
Also hardens IPv6: link-local multicast and interface-local multicast
are now rejected; DNS-resolved v6 addrs are checked too.
Symptom log (prod tenant hongmingwang):
ProxyA2A: unsafe URL for workspace a8af9d79-...: forbidden private/metadata
IP: 172.31.47.119
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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