sulthan
27cf0955de
Closes #24. Child of #18; based on current main (includes Postgres, Reader table, Discord OAuth).
## What
Each Reader's userscript credential is derived from `TOKEN_KEY`, their Discord id and a token epoch (HMAC-SHA256, hex); only its SHA-256 sits in `readers.token_sha256` (new `token_epoch` column, migration 0006). One credential authenticates the script download path and the API bearer header.
- `internal/token`: derivation + hashing; the seed refreshes the owner's epoch-0 hash only before first rotation, so a restart can never resurrect a rotated-away credential
- `httpmw.Auth`/`ResolveReader`: acting Reader resolved from the credential hash, stashed in request context; the retired global `API_TOKEN` resolves to the owner until `API_TOKEN_GRACE_UNTIL` (enforced in code, logged per use) on both the bearer and script-download paths
- Userscript handler renders the bindmounted file with the resolved Reader's credential substituted for `__API_TOKEN__`; a legacy-path request during grace serves the derived credential, so installed devices self-migrate on their next update poll
- Web UI: "Userscripts" panel — session-gated install endpoints render the script directly (credential never in markup, address bar, or a redirect), confirm-gated rotation with an atomic epoch bump + hash rewrite and a reinstall warning
- Both userscripts carry `__API_TOKEN__` placeholders; the committed global-token literal is removed
## Design note
Credentials are derived rather than stored-random because the server must rebuild install URLs after restarts while the DB holds only hashes. HMAC output is high-entropy and unbrute-forceable; the AC's intent (unguessable, DB-leak-proof) is met.
## Deploy (also in DEPLOY.md)
1. Add `TOKEN_KEY` (`openssl rand -hex 32`) — required; changing it later invalidates every credential.
2. Keep `API_TOKEN` + set `API_TOKEN_GRACE_UNTIL` for the 14-day window.
3. After deploy, sign in → Userscripts → reinstall both scripts on every device. This also retires the old global credential for real — its literal survives in git history (present since 0ef5286), so rotation is what kills it.
## Verification
- Full Go suite green against real Postgres per test; userscript JS suite 45/45
- New router-level tests: per-Reader isolation (read/write/delete), grace expiry on bearer + script path, self-migrating legacy path, install serving, rotation (old cred 401/404, new cred works, install renders new credential), app page leaks no credential
- Store tests: hash lookup, token info, atomic rotation with stale-epoch rejection, rotation survives restart
- Live smoke of the built binary: grace acceptance logged, derived auth, substitution, restart resilience, stored hash = SHA-256 of derived credential
Reviewed-on: #32
Co-authored-by: Sulthan Zaki <sultankiki05@gmail.com>
Co-committed-by: Sulthan Zaki <sultankiki05@gmail.com>
38 lines
1.5 KiB
Go
38 lines
1.5 KiB
Go
package token
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import (
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"crypto/hmac"
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"crypto/sha256"
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"encoding/hex"
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"strconv"
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)
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// Token derives one Reader's userscript credential from the deployment
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// secret, the Reader's Discord id and their token epoch.
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//
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// The credential is deterministic rather than stored random because the
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// server must be able to rebuild the install URL after a restart while the
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// database holds only hashes: a random token with no plaintext copy anywhere
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// would be unreconstructible, and keeping plaintext in memory would break
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// every install link on restart. HMAC output is high-entropy, indistinguishable
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// from random to anyone without the secret, and changes whenever the epoch
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// does — which is what rotation is. The stored form is Hash of this value,
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// so a database leak yields nothing but hashes of unguessable strings.
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func Token(key []byte, discordID string, epoch int64) string {
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mac := hmac.New(sha256.New, key)
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// The separator is unambiguous: discord ids are decimal snowflakes and
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// epochs are plain integers, so no two (id, epoch) pairs can collide.
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mac.Write([]byte(discordID))
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mac.Write([]byte{0})
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mac.Write([]byte(strconv.FormatInt(epoch, 10)))
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return hex.EncodeToString(mac.Sum(nil))
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}
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// Hash is the SHA-256 of a credential — the only form that ever touches the
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// database (readers.token_sha256). SHA-256 rather than a password hash is
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// deliberate: these are unguessable values with nothing to brute-force, so a
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// slow hash would only add per-request cost.
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func Hash(cred string) [32]byte {
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return sha256.Sum256([]byte(cred))
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}
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