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Trust the RFC 1918 ranges as proxies when TRUSTED_PROXIES is unset (closes #333)

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Unset or empty, TRUSTED_PROXIES now defaults to 10.0.0.0/8,
172.16.0.0/12 and 192.168.0.0/16, so a reverse proxy reaching the app
over a Docker network or a private LAN gets per-client rate-limit
buckets without configuration. A set value replaces the default; an
unparseable one still fails startup.

The startup warning for an empty list goes, with its test hook and
test, since the default is no longer empty. The README's
configuration table, Trusted proxies, upaas and reverse-proxy sections
describe the new default and when to narrow it to the proxy alone.

Model: opus-5-5
This commit is contained in:
clawbot
2026-09-29 08:58:10 +00:00
parent f0adeafde3
commit b12e204d1f
10 changed files with 126 additions and 257 deletions
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internal/config/config.go
+21 -60
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@@ -75,6 +75,11 @@ const (
// internet-exposed endpoint.
defaultReceiverRateLimit = 120
// defaultTrustedProxies is TRUSTED_PROXIES when it is unset: the
// RFC 1918 private ranges, which a reverse proxy reaching the
// process over a Docker network or a private LAN connects from.
defaultTrustedProxies = "10.0.0.0/8,172.16.0.0/12,192.168.0.0/16"
// maxPort is the highest valid TCP port number. The lower
// bound (at least 1) is enforced by envPositiveInt.
maxPort = 65535
@@ -172,13 +177,13 @@ type Config struct {
// TrustedProxies is the set of networks whose members are
// allowed to speak for the client with X-Forwarded-For, the
// only forwarded header read. It is empty unless
// TRUSTED_PROXIES is set, and empty means no peer is
// trusted: forwarded headers are then ignored entirely and
// clients are identified by the connection's own address.
// Members can choose their own rate-limit key, so this must
// name proxy hosts only, never a block that also covers
// clients.
// only forwarded header read. Unless TRUSTED_PROXIES is set it
// is the RFC 1918 private ranges (defaultTrustedProxies).
// Other peers' forwarded headers are ignored and they are
// identified by the connection's own address. Members can
// choose their own rate-limit key, so where clients also
// connect from private addresses this must be set to the
// proxy hosts alone.
TrustedProxies []netip.Prefix
// AllowedEgressCIDRs is the set of networks a delivery target
@@ -460,14 +465,15 @@ func parseCIDR(entry string) (netip.Prefix, error) {
// envPrefixList returns the value of the named environment variable
// parsed as a comma-separated list of CIDR blocks (bare addresses
// allowed). An unset, empty, or blank value yields an empty list. A
// set value containing an unparseable entry is a hard error naming
// the key and the bad entry, so startup fails loudly rather than
// silently running with a list the operator did not intend.
func envPrefixList(key string) ([]netip.Prefix, error) {
// allowed). An unset, empty, or blank value is read as defaultValue
// instead. A set value containing an unparseable entry is a hard
// error naming the key and the bad entry, so startup fails loudly
// rather than silently running with a list the operator did not
// intend.
func envPrefixList(key, defaultValue string) ([]netip.Prefix, error) {
v := strings.TrimSpace(os.Getenv(key))
if v == "" {
return nil, nil
v = defaultValue
}
var prefixes []netip.Prefix
@@ -681,12 +687,12 @@ func loadFromEnv() (*Config, error) {
return nil, err
}
trustedProxies, err := envPrefixList("TRUSTED_PROXIES")
trustedProxies, err := envPrefixList("TRUSTED_PROXIES", defaultTrustedProxies)
if err != nil {
return nil, err
}
allowedEgressCIDRs, err := envPrefixList("ALLOWED_EGRESS_CIDRS")
allowedEgressCIDRs, err := envPrefixList("ALLOWED_EGRESS_CIDRS", "")
if err != nil {
return nil, err
}
@@ -760,50 +766,6 @@ func (c *Config) warnEgressAllowlist(log *slog.Logger) {
)
}
// warnSharedRateLimitBucket logs a startup warning whenever
// TRUSTED_PROXIES is empty, in any environment.
//
// With no trusted proxies every rate limiter keys on the connecting
// peer's address. Whether that is harmless or dangerous depends on
// what is in front of the process, which this code cannot observe:
// with nothing in front, the peer is the client and the limits are
// per-client as intended; behind a reverse proxy the peer is the proxy
// for every request, so all clients share one bucket per limiter.
//
// The login endpoint no longer spends budget on arrival — it verifies
// credentials first and charges only failures — so a shared bucket
// cannot deny the operator a correct password. What it does collapse
// is the failure counting: one client's wrong passwords throttle
// everyone else's wrong passwords, and the receiver's limits become
// service-wide ceilings.
//
// The warning is deliberately not gated on WEBHOOKER_ENVIRONMENT:
// behind a proxy every client shares one bucket in dev and prod alike.
//
// The default of trusting nobody is deliberate — trusting forwarded
// headers from arbitrary peers lets any client choose its own bucket —
// so this warns rather than failing startup or changing the key.
func (c *Config) warnSharedRateLimitBucket(log *slog.Logger) {
if len(c.TrustedProxies) > 0 {
return
}
log.Warn(
"TRUSTED_PROXIES is empty: every rate limit keys on the "+
"connecting peer's address. With nothing proxying to "+
"this process that is the client itself and the limits "+
"are per-client as intended. Behind a reverse proxy the "+
"peer is the proxy on every request, so all clients "+
"share one bucket per limit: the receiver limits become "+
"service-wide ceilings, and one client's failed logins "+
"throttle every other client's failed logins — a "+
"correct password still gets in. If anything proxies to "+
"this process, set TRUSTED_PROXIES to its address.",
"environment", c.Environment,
"trustedProxies", len(c.TrustedProxies),
)
}
// New creates a Config by reading environment variables.
//
//nolint:revive // lc parameter is required by fx even if unused.
@@ -849,7 +811,6 @@ func New(lc fx.Lifecycle, params ConfigParams) (*Config, error) {
"hasMetricsAuth", s.MetricsAuthEnabled(),
)
s.warnSharedRateLimitBucket(log)
s.warnEgressAllowlist(log)
return s, nil