mitm: add server's own hostname as SAN on minted leaf certs#166
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dangtony98 merged 3 commits intomainfrom May 11, 2026
Merged
mitm: add server's own hostname as SAN on minted leaf certs#166dangtony98 merged 3 commits intomainfrom
dangtony98 merged 3 commits intomainfrom
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Clients that route HTTPS_PROXY to the agent-vault MITM proxy and TLS-verify against the proxy's own hostname (rather than the upstream SNI) currently fail because minted leaves only carry the upstream's SAN. Reuse the existing AGENT_VAULT_ADDR / baseURL plumbing to add the proxy's hostname as an additional SAN on every leaf, so the proxy-hop handshake matches without a shim. Routes IP literals into IPAddresses and DNS names into DNSNames, deduping against the primary SNI.
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The prior comment claimed "malformed entries are silently dropped," but the only filtering in New() is an empty-string check; non-IP entries are treated as DNS names without further validation.
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Addresses review feedback on PR #166: - ExtraSANs entries now run through validateSNI so malformed inputs (underscores, leading hyphens, spaces, etc.) are silently dropped instead of being appended to DNSNames verbatim. Docstring updated to match. - Extra-DNS dedup against the per-request SNI uses strings.EqualFold, matching RFC 6125 case-insensitive DNS-ID semantics. Avoids redundant SANs when AGENT_VAULT_ADDR carries mixed case. - .env.example mentions the new MITM SAN-injection side effect of AGENT_VAULT_ADDR, in line with the docs/ updates and CLAUDE.md's env-var doc convention.
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Summary
HTTPS_PROXYto the agent-vault MITM proxy and TLS-verify against the proxy's own hostname (rather than the upstream SNI) currently fail because minted leaves only carry the upstream's SAN. Today the workaround is aInsecureSkipVerifyshim on the client side.AGENT_VAULT_ADDR/baseURLplumbing (already threaded intomitm.Options.BaseURLfor help-link text) to add the proxy's hostname as an additional SAN on every minted leaf. Newca.Options.ExtraSANs []stringis populated once at boot inattachMITMIfEnabledfromsrv.BaseURL();MintLeafappends it to the cert template, routing IP literals intoIPAddressesand DNS names intoDNSNames, deduping against the primary SNI.AGENT_VAULT_ADDR=http://agent-vault-hnh0:14321on a service and every minted leaf now carriesagent-vault-hnh0as a SAN — the shim can be deleted.Implementation notes
*tls.Certificateinstances remain consistent).MintLeaf's signature is unchanged; the two MITM call sites (internal/mitm/proxy.go:120,internal/mitm/connect.go:110) are untouched.AGENT_VAULT_ADDRenv-var description updated in bothdocs/self-hosting/environment-variables.mdxanddocs/reference/cli.mdxto mention the new SAN behavior.Test plan
make test— full Go suite green; newTestMintLeaf_IncludesExtraDNSSansandTestMintLeaf_IncludesExtraIPSanscover the SAN injection + dedup paths and the IP-vs-DNS routing.go vet ./...clean.AGENT_VAULT_ADDR=http://agent-vault-hnh0:14321, redeploy, confirmopenssl s_client -connect agent-vault-hnh0:14322 -servername api.linear.app | openssl x509 -text -nooutshowsDNS:agent-vault-hnh0alongsideDNS:api.linear.app, then drop the talent-agentInsecureSkipVerifyshim and verify the client connects clean.