fix: don't DNS-resolve redirect_uris during client registration#488
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leifj wants to merge 1 commit into
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fix: don't DNS-resolve redirect_uris during client registration#488leifj wants to merge 1 commit into
leifj wants to merge 1 commit into
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The redirect_uri validator resolved hostnames via net.LookupIP() and rejected URIs whose hostnames didn't resolve (for http/https). This caused ccTLD domains like example.se to fail registration while example.org (which resolves to an IANA-reserved IP) succeeded. Redirect URIs are never fetched server-side — they're URLs the browser is redirected to. The SSRF concern that motivated the DNS check doesn't apply here. Remove the DNS resolution and private-IP blocking from the redirect_uri validator, keeping only the syntactic checks required by RFC 6749 (scheme present, no fragment). The safe_uri validator (used for server-side fetches like logo_uri) retains its DNS/SSRF checks. Add test cases for ccTLD and non-resolving hostnames.
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Fixes #487
Problem
The
redirect_urivalidator resolved hostnames vianet.LookupIP()and rejected URIs whose hostnames didn't resolve (for http/https). This caused ccTLD domains likeexample.seto fail registration whileexample.org(which resolves to an IANA-reserved IP) succeeded.Fix
Remove DNS resolution and private-IP blocking from the
redirect_urivalidator. Redirect URIs are never fetched server-side — they're URLs the browser is redirected to. The SSRF concern that motivated the DNS check doesn't apply.Keep only the syntactic checks required by RFC 6749 (scheme present, no fragment).
The
safe_urivalidator (used for server-side fetches likelogo_uri) retains its DNS/SSRF checks.Tests
Added test cases for ccTLD (
example.se) and non-resolving hostnames (nonexistent.test).