fix: keep env proxies off SSRF base transport - #93
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NewTransport is the shared dial/timeout base used by the CAS server when installing DialContext IP filters. Honor HTTP(S)_PROXY only in New() for CLI/library clients so a proxy hop cannot bypass origin IP checks.
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Problem
httpclient.NewTransportsetProxy: http.ProxyFromEnvironment. The CAS server builds its outbound client from that base and installs SSRF filtering onDialContext.When
HTTP_PROXY/HTTPS_PROXYis set, the transport dials the proxy, not the origin. The DialContext control only validates the proxy address, so a reachable proxy can fetch blocked ranges (loopback, link-local metadata, RFC1918, CGNAT, …) that the SSRF filter is meant to stop.Change
Proxynil onNewTransport(SSRF / custom-Dial base)ProxyFromEnvironmentonly inNew()(CLI get/seed, library Fetcher default, handler nil-client fallback)Newsets proxy without mutating a laterNewTransport()Behavior note: server origin/upstream fetches no longer follow env proxies. CLI/library clients still do.
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