sneak
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The SSRF blocklist had no escape hatch, so the thing webhooker is mostly for — taking a public webhook and forwarding it to something on your own network — could not be configured at all. Every private address, Docker sibling and loopback service was permanently unreachable as a delivery destination. ALLOWED_EGRESS_CIDRS (default empty) names blocks that delivery targets may reach despite the default blocklist. It is an allowlist and only ever adds destinations: there is no boolean, and no value disables SSRF protection wholesale. Empty, the guard behaves exactly as before. A fixed set of addresses is refused before the allowlist is consulted, so no supplied CIDR opens one — not the exact address, not a supernet, not 0.0.0.0/0 or ::/0. It is the two link-local blocks (169.254.0.0/16, fe80::/10) plus host routes for the cloud metadata endpoints that sit outside them: AWS's IPv6 IMDS at fd00:ec2::254, which lives in ordinary ULA space, and Alibaba's 100.100.100.200, which lives in CGNAT. Allowlisting fd00::/8 or 100.64.0.0/10 (Tailscale's range) is an ordinary thing for an operator to do and must not reopen instance-credential theft. The IPv4-compatible (::a9fe:a9fe) and NAT64 (64:ff9b::a9fe:a9fe) spellings of 169.254.169.254 are listed too, because To4() does not normalise them into the link-local block the way it does the IPv4-mapped form. Reaching any of these is credential theft rather than delivery to an internal service. The policy now lives in one function, Guard.checkIP, which both target-creation validation and the delivery dialer call. The two paths previously decided separately, which is how they came to disagree about a destination. The guard is built once from config and injected via fx into both the handlers and the delivery engine, so there is a single instance and a single answer. A set-but-unparseable value aborts startup naming the variable, reusing the existing envPrefixList parser. A non-empty list is logged at startup with the blocks spelled out, not counted, so the hole is visible in the log of any deployment that has one. Tests: an allowlisted loopback CIDR both validates and delivers to a live server (and the same URL still fails without the allowlist); a private address outside the listed block stays refused on both paths; every unconditionally blocked address stays refused on both paths under an allowlist that covers it, and the set itself is pinned entry by entry; public addresses are unaffected either way; and config coverage for parsing, startup abort, and the warning's contents.
53 lines
1.5 KiB
Go
53 lines
1.5 KiB
Go
package config
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import "log/slog"
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// This file exposes the unexported environment parsing helpers to
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// the external config_test package so each helper can be covered by
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// its own table-driven test without weakening the package API.
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// WarnSharedRateLimitBucketForTest loads a Config from the current
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// environment and emits its startup warnings to log. The real logger
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// writes to stdout, so this lets the warning's firing condition be
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// asserted against a handler the test controls.
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func WarnSharedRateLimitBucketForTest(log *slog.Logger) error {
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c, err := loadFromEnv()
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if err != nil {
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return err
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}
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c.warnSharedRateLimitBucket(log)
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return nil
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}
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// WarnEgressAllowlistForTest loads a Config from the current
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// environment and emits its egress-allowlist startup warning to
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// log, so a test can assert both that the warning fires only when
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// the list is non-empty and that it names the blocks it opened.
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func WarnEgressAllowlistForTest(log *slog.Logger) error {
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c, err := loadFromEnv()
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if err != nil {
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return err
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}
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c.warnEgressAllowlist(log)
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return nil
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}
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// EnvBoolForTest exposes envBool.
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func EnvBoolForTest(key string, defaultValue bool) (bool, error) {
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return envBool(key, defaultValue)
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}
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// EnvPositiveIntForTest exposes envPositiveInt.
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func EnvPositiveIntForTest(key string, defaultValue int) (int, error) {
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return envPositiveInt(key, defaultValue)
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}
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// EnvPortForTest exposes envPort.
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func EnvPortForTest(key string, defaultValue int) (int, error) {
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return envPort(key, defaultValue)
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}
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