Fix hostname/address handling in tunnel proxies#496
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Tunnel mode had the two halves of the documented contract inverted. establish_proxy/2 built the CONNECT authority from the :hostname override, so a pinned-IP address was never sent to the proxy and DNS pinning silently stopped working through tunnels. upgrade_connection/3 then used the raw address as the TLS identity, so SNI, certificate verification, and the post-tunnel Host header / HTTP/2 :authority all used the address instead of the declared identity; with an :inet tuple address (documented as supported) the upgrade raised in String.to_charlist/1. Now the CONNECT request targets the connection address (with :inet tuples formatted via :inet.ntoa/1 and IPv6 addresses bracketed) while the TLS upgrade uses the same identity resolution as direct connections. The Host header of the CONNECT request is set to the authority-form target as required by RFC 9112, section 3.2.3; it previously named the proxy. The pkix_test_data/1 helper duplicated in two test modules moved to a shared Mint.TestCertificates support module.
Coverage Report for CI Build 42605087Coverage decreased (-0.009%) to 87.875%Details
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Jul 21, 2026
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Tunnel mode had the documented
address/:hostnamecontract inverted.establish_proxy/2built the CONNECT authority from the:hostnameidentity, so a pinned-IPaddresswas never sent to the proxy and DNS pinning silently stopped working through tunnels.upgrade_connection/3then used the rawaddressas the TLS identity, so SNI, certificate verification, and the post-tunnel Host header / HTTP/2:authorityall used the address instead of the declared identity (and an:inettuple address, which is documented as supported, crashed inString.to_charlist/1).The CONNECT request now targets the connection address (
:inettuples formatted with:inet.ntoa/1, IPv6 bracketed) and the tunnel TLS session uses the same identity resolution as direct connections. The CONNECT request's Host header is now identical to the authority-form target as RFC 9112 (section 3.2.3) requires; it previously named the proxy. Offline regression tests cover the authority, the Host header, tuple addresses, and certificate verification against the:hostnameidentity through the tunnel (5 of the 7 new tests fail on main).Also extracts the
pkix_test_data/1helper that was duplicated across two test modules into a sharedMint.TestCertificatessupport module.