Crate fallow_license 

Offline Ed25519-signed license JWT verification for the fallow CLI.

This crate is the public-binary side of fallow’s paid-feature gating. It does NOT perform any network I/O; the license file is loaded from disk or environment, the signature is verified against a public key compiled in by the embedding binary, and the result is exposed as a LicenseStatus.

Storage precedence

License material is sourced in this order (first match wins):

1. $FALLOW_LICENSE environment variable (full JWT string).
2. $FALLOW_LICENSE_PATH environment variable (path to a file containing the JWT).
3. ~/.fallow/license.jwt (default path under the user’s home directory).

Algorithm pinning

Only Ed25519 (EdDSA) is accepted. The JWT header’s alg claim is verified to equal "EdDSA" after base64 decoding; we never trust the header to pick the algorithm.

Grace ladder

Matches Docker Desktop / JetBrains conventions. See grace_state.

Structs

LicenseClaims

JWT claims emitted by api.fallow.cloud for fallow CLI licenses.

Enums

Feature

Feature flag enum aligned with the protocol’s Feature strings.

LicenseError

Errors returned by load_and_verify when the license material is present but malformed (vs simply missing, which is reported via LicenseStatus::Missing).

LicenseStatus

Outcome of load_and_verify.

Constants

DEFAULT_HARD_FAIL_DAYS

Default cap on the grace window before hard-fail in the public CLI.

DEFAULT_SKEW_TOLERANCE_SECONDS

Default tolerance (in seconds) for iat clock skew: 24h.

SKEW_TOLERANCE_ENV

Env var name for overriding DEFAULT_SKEW_TOLERANCE_SECONDS.

WATERMARK_DAYS

Days post-expiry after which the public output gains a visible watermark.

Functions

current_unix_seconds

Wrapper around SystemTime::now() returning unix seconds.

default_license_path

Compute the canonical default license path (~/.fallow/license.jwt).

grace_state

Map a verified LicenseClaims to a LicenseStatus using the 7/cap/hard-fail ladder.

load_and_verify

Discover and load a license JWT according to the storage precedence rules, then verify it and apply the grace ladder.

load_raw_jwt

Resolve the JWT source according to storage precedence.

normalize_jwt

Strip whitespace and embedded line breaks from a pasted JWT.

skew_tolerance_seconds_from_env

Resolve the clock-skew tolerance (in seconds) from FALLOW_LICENSE_SKEW_TOLERANCE_SECONDS, falling back to DEFAULT_SKEW_TOLERANCE_SECONDS when the variable is unset, empty, whitespace-only, or unparsable.

user_home_dir

Resolve the user’s home directory in a cross-platform way.

verify_jwt

Verify a raw JWT string against the supplied public key and (optionally) the wall clock. The now parameter is the unix-seconds reference used to classify expiry; pass current_unix_seconds in production.

verify_jwt_with_skew

Verify a raw JWT string with an explicit clock-skew tolerance.