hush/vendor/github.com/redis/go-redis/v9/internal/arg.go
jx12n 4d9a26498e hush: one-time secret links the server cannot read
Paste a secret, get a link, send it. The first person to open it and press
Reveal sees the secret; the link dies at that moment. The recipient needs a
browser and nothing else — no account, no client, no installed tooling.

The server cannot read what it stores. AES-256-GCM happens in the browser and
the key lives in the URL fragment, which browsers never transmit, so hushd
holds ciphertext and no key material. That is a property of where the key sits
rather than a promise about our conduct, which is why there is deliberately no
endpoint accepting a plaintext secret and no server-side-encryption fallback:
two guarantees behind one URL would be worse than one honest guarantee.

Three decisions carry the design:

  * GET /s/{id} touches NO storage, not even to check existence. Slack, Teams,
    WhatsApp, iMessage and Outlook Safe Links all fetch a URL before a human
    sees it, so destroying on GET would destroy most secrets in transit and the
    recipient's "already used" would be indistinguishable from interception.
    Only POST /reveal consumes. Bot user-agent detection is an arms race;
    removing the side effect from GET is not. Pinned by
    TestGettingTheRevealPageNeverConsumesTheSecret.
  * Destruction is one Redis GETDEL, which is atomic. GET-then-DEL has a window
    where two simultaneous readers both win, and for a one-time secret that
    window is the product. The store contract demands atomicity and the same
    concurrency test runs against both implementations.
  * Missing, already-revealed, expired and evicted are ONE indistinguishable
    410. Separating them would confirm to a prober that a given link was real.

The secret id IS the capability, so secret.ID is a struct whose every
accidental path — %v, %s, String(), slog, json.Marshal — emits a redacted
handle or refuses, and the raw value needs an explicit Value(). The first
version tried to prevent leaks by implementing no String() at all; its own test
caught that Go's fmt prints unexported fields anyway, so forbidding the method
had removed the control rather than the leak.

Operationally: structured JSON on stdout in the fleet's wire format, which
Vector already collects with no annotation; six hush_* metrics on the chassis
registry with no id, IP or path in any label; five alert rules wired into
vmalert. The public Ingress enumerates /, /s/ and /api/ so /metrics, /healthz
and /readyz share the port but are unreachable from the internet — no
basic-auth middleware to maintain and get wrong.

Dependencies are vendored because go-chassis is private: the Woodpecker test
step and the in-cluster Kaniko build both run -mod=vendor with GOPROXY=off and
hold no git credential.

cmd/hush-mcp is a stdio MCP server doing the same client-side crypto locally,
so using hush from an agent preserves the same guarantee as using it from a
browser.
2026-09-03 00:08:38 -06:00

59 lines
1.3 KiB
Go

package internal
import (
"fmt"
"strconv"
"time"
"github.com/redis/go-redis/v9/internal/util"
)
func AppendArg(b []byte, v interface{}) []byte {
switch v := v.(type) {
case nil:
return append(b, "<nil>"...)
case string:
return appendUTF8String(b, util.StringToBytes(v))
case []byte:
return appendUTF8String(b, v)
case int:
return strconv.AppendInt(b, int64(v), 10)
case int8:
return strconv.AppendInt(b, int64(v), 10)
case int16:
return strconv.AppendInt(b, int64(v), 10)
case int32:
return strconv.AppendInt(b, int64(v), 10)
case int64:
return strconv.AppendInt(b, v, 10)
case uint:
return strconv.AppendUint(b, uint64(v), 10)
case uint8:
return strconv.AppendUint(b, uint64(v), 10)
case uint16:
return strconv.AppendUint(b, uint64(v), 10)
case uint32:
return strconv.AppendUint(b, uint64(v), 10)
case uint64:
return strconv.AppendUint(b, v, 10)
case float32:
return strconv.AppendFloat(b, float64(v), 'f', -1, 64)
case float64:
return strconv.AppendFloat(b, v, 'f', -1, 64)
case bool:
if v {
return append(b, "true"...)
}
return append(b, "false"...)
case time.Time:
return v.AppendFormat(b, time.RFC3339Nano)
default:
return append(b, fmt.Sprint(v)...)
}
}
func appendUTF8String(dst []byte, src []byte) []byte {
dst = append(dst, src...)
return dst
}