WeKnora deployment source with the reviewed wiki identity, summary and recovery fixes

internal/utils/oidc_state.go

@@ -0,0 +1,106 @@
+package utils
+
+import (
+	"crypto/hmac"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"os"
+	"strings"
+	"sync"
+	"time"
+)
+
+const oidcStateMaxAge = 10 * time.Minute
+
+// OIDCStatePayload is the signed OIDC authorization state carried in the
+// redirect URL and validated on callback.
+type OIDCStatePayload struct {
+	Nonce       string `json:"nonce"`
+	RedirectURI string `json:"redirect_uri,omitempty"`
+	IssuedAt    int64  `json:"iat"`
+}
+
+var (
+	oidcStateSecretOnce sync.Once
+	oidcStateSecret     string
+)
+
+func oidcStateSigningKey() string {
+	oidcStateSecretOnce.Do(func() {
+		if envSecret := strings.TrimSpace(os.Getenv("JWT_SECRET")); envSecret != "" {
+			oidcStateSecret = envSecret
+			return
+		}
+		randomBytes := make([]byte, 32)
+		if _, err := rand.Read(randomBytes); err != nil {
+			panic(fmt.Sprintf("failed to generate OIDC state signing key: %v", err))
+		}
+		oidcStateSecret = base64.StdEncoding.EncodeToString(randomBytes)
+	})
+	return oidcStateSecret
+}
+
+// SignOIDCState returns a tamper-evident state token: base64url(payload).base64url(hmac).
+func SignOIDCState(payload *OIDCStatePayload) (string, error) {
+	if payload == nil {
+		return "", errors.New("oidc state payload is required")
+	}
+	if strings.TrimSpace(payload.Nonce) == "" {
+		return "", errors.New("oidc state nonce is required")
+	}
+	if strings.TrimSpace(payload.RedirectURI) == "" {
+		return "", errors.New("oidc state redirect_uri is required")
+	}
+	if payload.IssuedAt == 0 {
+		payload.IssuedAt = time.Now().Unix()
+	}
+	raw, err := json.Marshal(payload)
+	if err != nil {
+		return "", fmt.Errorf("marshal oidc state: %w", err)
+	}
+	mac := hmac.New(sha256.New, []byte(oidcStateSigningKey()))
+	mac.Write(raw)
+	sig := mac.Sum(nil)
+	return base64.RawURLEncoding.EncodeToString(raw) + "." + base64.RawURLEncoding.EncodeToString(sig), nil
+}
+
+// VerifyOIDCState validates the HMAC and freshness of a state token.
+func VerifyOIDCState(raw string) (*OIDCStatePayload, error) {
+	raw = strings.TrimSpace(raw)
+	parts := strings.Split(raw, ".")
+	if len(parts) != 2 {
+		return nil, errors.New("invalid oidc state format")
+	}
+	payloadBytes, err := base64.RawURLEncoding.DecodeString(parts[0])
+	if err != nil {
+		return nil, fmt.Errorf("decode oidc state payload: %w", err)
+	}
+	sigBytes, err := base64.RawURLEncoding.DecodeString(parts[1])
+	if err != nil {
+		return nil, fmt.Errorf("decode oidc state signature: %w", err)
+	}
+	mac := hmac.New(sha256.New, []byte(oidcStateSigningKey()))
+	mac.Write(payloadBytes)
+	if !hmac.Equal(mac.Sum(nil), sigBytes) {
+		return nil, errors.New("oidc state signature mismatch")
+	}
+	var payload OIDCStatePayload
+	if err := json.Unmarshal(payloadBytes, &payload); err != nil {
+		return nil, fmt.Errorf("unmarshal oidc state: %w", err)
+	}
+	if strings.TrimSpace(payload.RedirectURI) == "" {
+		return nil, errors.New("state.redirect_uri is required")
+	}
+	if payload.IssuedAt == 0 {
+		return nil, errors.New("state.iat is required")
+	}
+	issuedAt := time.Unix(payload.IssuedAt, 0)
+	if time.Since(issuedAt) > oidcStateMaxAge || time.Until(issuedAt) > time.Minute {
+		return nil, errors.New("oidc state expired or invalid timestamp")
+	}
+	return &payload, nil
+}