v0.1.0-alpha

Changes:
- Implement bootstrapping library for managing several concurrent internal services
- Refactor concurrency model for connections/logical clients and their associated I/O
- Refactor server context singleton
- Refactor error handling
    - Most errors are now gracefully sent to the FSD client directly encoded as an $ER packet,
      enhancing visibility and debugging
    - Most errors are now rightfully treated as non-fatal
- Refactor package/dependency graph
- Refactor calling conventions/interfaces for many packages
- Refactor database package
- Refactor post office

Features:
- Add VATSIM-esque HTTP/JSON "data feed"
- Add ephemeral in-memory database option
- Add user management REST API
- Add improved web interface
- Add MySQL support (drop SQLite support)

auth/jwt.go

@@ -0,0 +1,55 @@
+package auth
+
+import (
+	"errors"
+	"github.com/golang-jwt/jwt/v5"
+	"github.com/renorris/openfsd/servercontext"
+	"time"
+)
+
+// JWTVerifier is an frontend for verifying JWT tokens
+type JWTVerifier interface {
+	VerifyJWT(tokenStr string) (*jwt.Token, error)
+}
+
+// DefaultVerifier is the default implementation of JWTVerifier
+type DefaultVerifier struct{}
+
+// VerifyJWT verifies the signature, issuer, expiration times, and not-before times of a token string
+func (d DefaultVerifier) VerifyJWT(tokenStr string) (token *jwt.Token, err error) {
+	if token, err = jwt.Parse(tokenStr, func(token *jwt.Token) (interface{}, error) {
+		return servercontext.JWTKey(), nil
+	}, jwt.WithValidMethods([]string{"HS256"})); err != nil {
+		return nil, err
+	}
+
+	var issuer string
+	if issuer, err = token.Claims.GetIssuer(); err != nil {
+		return nil, err
+	}
+	if issuer != "openfsd" {
+		return nil, errors.New("issuer != openfsd")
+	}
+
+	// Verify expiration time
+	var expirationTime *jwt.NumericDate
+	if expirationTime, err = token.Claims.GetExpirationTime(); err != nil {
+		return nil, err
+	}
+
+	if expirationTime.Before(time.Now()) {
+		return nil, errors.New("token expired")
+	}
+
+	// Verify not-before time
+	var notBeforeTime *jwt.NumericDate
+	if notBeforeTime, err = token.Claims.GetNotBefore(); err != nil {
+		return nil, err
+	}
+
+	if notBeforeTime.After(time.Now()) {
+		return nil, errors.New("token not yet valid")
+	}
+
+	return
+}