feat(antigravity): configurable signature cache with bypass-mode validation

Antigravity 的 Claude thinking signature 处理新增 cache/bypass 双模式，并为 bypass 模式实现按 SIGNATURE-CHANNEL-SPEC.md 的签名校验。新增 antigravity-signature-cache-enabled 配置项（默认 true）： - cache mode（true）：使用服务端缓存的签名，行为与原有逻辑完全一致 - bypass mode（false）：直接使用客户端提供的签名，经过校验和归一化支持配置热重载，运行时可切换模式。校验流程： 1. 剥离历史 cache-mode 的 'modelGroup#' 前缀（如 claude#Exxxx → Exxxx） 2. 首字符必须为 'E'（单层编码）或 'R'（双层编码），否则拒绝 3. R 开头：base64 解码 → 内层必须以 'E' 开头 → 继续单层校验 4. E 开头：base64 解码 → 首字节必须为 0x12（Claude protobuf 标识） 5. 所有合法签名归一化为 R 形式（双层 base64）发往 Antigravity 后端非法签名处理策略： - 非严格模式（默认）：translator 静默丢弃无签名的 thinking block - 严格模式（antigravity-signature-bypass-strict: true）： executor 层在请求发往上游前直接返回 HTTP 400 按 SIGNATURE-CHANNEL-SPEC.md 解析 Claude 签名的完整 protobuf 结构： - Top-level Field 2（容器）→ Field 1（渠道块） - 渠道块提取：channel_id (Field 1)、infrastructure (Field 2)、 model_text (Field 6)、field7 (Field 7) - 计算 routing_class、infrastructure_class、schema_features - 使用 google.golang.org/protobuf/encoding/protowire 解析 - resolveThinkingSignature 拆分为 resolveCacheModeSignature / resolveBypassModeSignature - hasResolvedThinkingSignature：mode-aware 签名有效性判断（cache: len>=50 via HasValidSignature，bypass: non-empty） - validateAntigravityRequestSignatures：executor 预检，仅在 bypass + strict 模式下拦截非法签名返回 400 - 响应侧签名缓存逻辑与 cache mode 集成 - Cache mode 行为完全保留：无 '#' 前缀的原生签名静默丢弃
2026-03-31 14:15:06 +08:00
parent 1dba2d0f81
commit cf249586a9
11 changed files with 1494 additions and 62 deletions
@@ -0,0 +1,351 @@
+package claude
+
+import (
+	"encoding/base64"
+	"fmt"
+	"strings"
+	"unicode/utf8"
+
+	"github.com/router-for-me/CLIProxyAPI/v6/internal/cache"
+	"github.com/tidwall/gjson"
+	"google.golang.org/protobuf/encoding/protowire"
+)
+
+// maxBypassSignatureLen caps the signature string length (after prefix stripping)
+// to prevent base64 decode from allocating excessive memory on malicious input.
+const maxBypassSignatureLen = 8192
+
+type claudeSignatureTree struct {
+	EncodingLayers      int
+	ChannelID           uint64
+	Field2              *uint64
+	RoutingClass        string
+	InfrastructureClass string
+	SchemaFeatures      string
+	ModelText           string
+	LegacyRouteHint     string
+	HasField7           bool
+}
+
+// ValidateClaudeBypassSignatures validates Claude thinking signatures in bypass mode.
+func ValidateClaudeBypassSignatures(inputRawJSON []byte) error {
+	messages := gjson.GetBytes(inputRawJSON, "messages")
+	if !messages.IsArray() {
+		return nil
+	}
+
+	messageResults := messages.Array()
+	for i := 0; i < len(messageResults); i++ {
+		contentResults := messageResults[i].Get("content")
+		if !contentResults.IsArray() {
+			continue
+		}
+		parts := contentResults.Array()
+		for j := 0; j < len(parts); j++ {
+			part := parts[j]
+			if part.Get("type").String() != "thinking" {
+				continue
+			}
+
+			rawSignature := strings.TrimSpace(part.Get("signature").String())
+			if rawSignature == "" {
+				return fmt.Errorf("messages[%d].content[%d]: missing thinking signature", i, j)
+			}
+
+			if _, err := normalizeClaudeBypassSignature(rawSignature); err != nil {
+				return fmt.Errorf("messages[%d].content[%d]: %w", i, j, err)
+			}
+		}
+	}
+
+	return nil
+}
+
+// normalizeClaudeBypassSignature validates a raw Claude signature and returns
+// it in the double-layer (R-starting) form expected by upstream.
+func normalizeClaudeBypassSignature(rawSignature string) (string, error) {
+	sig := strings.TrimSpace(rawSignature)
+	if sig == "" {
+		return "", fmt.Errorf("empty signature")
+	}
+
+	if idx := strings.IndexByte(sig, '#'); idx >= 0 {
+		sig = strings.TrimSpace(sig[idx+1:])
+	}
+
+	if sig == "" {
+		return "", fmt.Errorf("empty signature after stripping prefix")
+	}
+
+	if len(sig) > maxBypassSignatureLen {
+		return "", fmt.Errorf("signature exceeds maximum length (%d bytes)", maxBypassSignatureLen)
+	}
+
+	switch sig[0] {
+	case 'R':
+		if err := validateDoubleLayerSignature(sig); err != nil {
+			return "", err
+		}
+		return sig, nil
+	case 'E':
+		if err := validateSingleLayerSignature(sig); err != nil {
+			return "", err
+		}
+		return base64.StdEncoding.EncodeToString([]byte(sig)), nil
+	default:
+		return "", fmt.Errorf("invalid signature: expected 'E' or 'R' prefix, got %q", string(sig[0]))
+	}
+}
+
+func validateDoubleLayerSignature(sig string) error {
+	decoded, err := base64.StdEncoding.DecodeString(sig)
+	if err != nil {
+		return fmt.Errorf("invalid double-layer signature: base64 decode failed: %w", err)
+	}
+	if len(decoded) == 0 {
+		return fmt.Errorf("invalid double-layer signature: empty after decode")
+	}
+	if decoded[0] != 'E' {
+		return fmt.Errorf("invalid double-layer signature: inner does not start with 'E', got 0x%02x", decoded[0])
+	}
+	return validateSingleLayerSignatureContent(string(decoded), 2)
+}
+
+func validateSingleLayerSignature(sig string) error {
+	return validateSingleLayerSignatureContent(sig, 1)
+}
+
+func validateSingleLayerSignatureContent(sig string, encodingLayers int) error {
+	decoded, err := base64.StdEncoding.DecodeString(sig)
+	if err != nil {
+		return fmt.Errorf("invalid single-layer signature: base64 decode failed: %w", err)
+	}
+	if len(decoded) == 0 {
+		return fmt.Errorf("invalid single-layer signature: empty after decode")
+	}
+	if decoded[0] != 0x12 {
+		return fmt.Errorf("invalid Claude signature: expected first byte 0x12, got 0x%02x", decoded[0])
+	}
+	if !cache.SignatureBypassStrictMode() {
+		return nil
+	}
+	_, err = inspectClaudeSignaturePayload(decoded, encodingLayers)
+	return err
+}
+
+func inspectDoubleLayerSignature(sig string) (*claudeSignatureTree, error) {
+	decoded, err := base64.StdEncoding.DecodeString(sig)
+	if err != nil {
+		return nil, fmt.Errorf("invalid double-layer signature: base64 decode failed: %w", err)
+	}
+	if len(decoded) == 0 {
+		return nil, fmt.Errorf("invalid double-layer signature: empty after decode")
+	}
+	if decoded[0] != 'E' {
+		return nil, fmt.Errorf("invalid double-layer signature: inner does not start with 'E', got 0x%02x", decoded[0])
+	}
+	return inspectSingleLayerSignatureWithLayers(string(decoded), 2)
+}
+
+func inspectSingleLayerSignature(sig string) (*claudeSignatureTree, error) {
+	return inspectSingleLayerSignatureWithLayers(sig, 1)
+}
+
+func inspectSingleLayerSignatureWithLayers(sig string, encodingLayers int) (*claudeSignatureTree, error) {
+	decoded, err := base64.StdEncoding.DecodeString(sig)
+	if err != nil {
+		return nil, fmt.Errorf("invalid single-layer signature: base64 decode failed: %w", err)
+	}
+	if len(decoded) == 0 {
+		return nil, fmt.Errorf("invalid single-layer signature: empty after decode")
+	}
+	return inspectClaudeSignaturePayload(decoded, encodingLayers)
+}
+
+func inspectClaudeSignaturePayload(payload []byte, encodingLayers int) (*claudeSignatureTree, error) {
+	if len(payload) == 0 {
+		return nil, fmt.Errorf("invalid Claude signature: empty payload")
+	}
+	if payload[0] != 0x12 {
+		return nil, fmt.Errorf("invalid Claude signature: expected first byte 0x12, got 0x%02x", payload[0])
+	}
+	container, err := extractBytesField(payload, 2, "top-level protobuf")
+	if err != nil {
+		return nil, err
+	}
+	channelBlock, err := extractBytesField(container, 1, "Claude Field 2 container")
+	if err != nil {
+		return nil, err
+	}
+	return inspectClaudeChannelBlock(channelBlock, encodingLayers)
+}
+
+func inspectClaudeChannelBlock(channelBlock []byte, encodingLayers int) (*claudeSignatureTree, error) {
+	tree := &claudeSignatureTree{
+		EncodingLayers:      encodingLayers,
+		RoutingClass:        "unknown",
+		InfrastructureClass: "infra_unknown",
+		SchemaFeatures:      "unknown_schema_features",
+	}
+	haveChannelID := false
+	hasField6 := false
+	hasField7 := false
+
+	err := walkProtobufFields(channelBlock, func(num protowire.Number, typ protowire.Type, raw []byte) error {
+		switch num {
+		case 1:
+			if typ != protowire.VarintType {
+				return fmt.Errorf("invalid Claude signature: Field 2.1.1 channel_id must be varint")
+			}
+			channelID, err := decodeVarintField(raw, "Field 2.1.1 channel_id")
+			if err != nil {
+				return err
+			}
+			tree.ChannelID = channelID
+			haveChannelID = true
+		case 2:
+			if typ != protowire.VarintType {
+				return fmt.Errorf("invalid Claude signature: Field 2.1.2 field2 must be varint")
+			}
+			field2, err := decodeVarintField(raw, "Field 2.1.2 field2")
+			if err != nil {
+				return err
+			}
+			tree.Field2 = &field2
+		case 6:
+			if typ != protowire.BytesType {
+				return fmt.Errorf("invalid Claude signature: Field 2.1.6 model_text must be bytes")
+			}
+			modelBytes, err := decodeBytesField(raw, "Field 2.1.6 model_text")
+			if err != nil {
+				return err
+			}
+			if !utf8.Valid(modelBytes) {
+				return fmt.Errorf("invalid Claude signature: Field 2.1.6 model_text is not valid UTF-8")
+			}
+			tree.ModelText = string(modelBytes)
+			hasField6 = true
+		case 7:
+			if typ != protowire.VarintType {
+				return fmt.Errorf("invalid Claude signature: Field 2.1.7 must be varint")
+			}
+			if _, err := decodeVarintField(raw, "Field 2.1.7"); err != nil {
+				return err
+			}
+			hasField7 = true
+			tree.HasField7 = true
+		}
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+	if !haveChannelID {
+		return nil, fmt.Errorf("invalid Claude signature: missing Field 2.1.1 channel_id")
+	}
+
+	switch tree.ChannelID {
+	case 11:
+		tree.RoutingClass = "routing_class_11"
+	case 12:
+		tree.RoutingClass = "routing_class_12"
+	}
+
+	if tree.Field2 == nil {
+		tree.InfrastructureClass = "infra_default"
+	} else {
+		switch *tree.Field2 {
+		case 1:
+			tree.InfrastructureClass = "infra_aws"
+		case 2:
+			tree.InfrastructureClass = "infra_google"
+		default:
+			tree.InfrastructureClass = "infra_unknown"
+		}
+	}
+
+	switch {
+	case hasField6:
+		tree.SchemaFeatures = "extended_model_tagged_schema"
+	case !hasField6 && !hasField7 && len(channelBlock) >= 70 && len(channelBlock) <= 72:
+		tree.SchemaFeatures = "compact_schema"
+	}
+
+	if tree.ChannelID == 11 {
+		switch {
+		case tree.Field2 == nil:
+			tree.LegacyRouteHint = "legacy_default_group"
+		case *tree.Field2 == 1:
+			tree.LegacyRouteHint = "legacy_aws_group"
+		case *tree.Field2 == 2 && tree.EncodingLayers == 2:
+			tree.LegacyRouteHint = "legacy_vertex_direct"
+		case *tree.Field2 == 2 && tree.EncodingLayers == 1:
+			tree.LegacyRouteHint = "legacy_vertex_proxy"
+		case *tree.Field2 == 2:
+			tree.LegacyRouteHint = "legacy_vertex_group"
+		}
+	}
+
+	return tree, nil
+}
+
+func extractBytesField(msg []byte, fieldNum protowire.Number, scope string) ([]byte, error) {
+	var value []byte
+	err := walkProtobufFields(msg, func(num protowire.Number, typ protowire.Type, raw []byte) error {
+		if num != fieldNum {
+			return nil
+		}
+		if typ != protowire.BytesType {
+			return fmt.Errorf("invalid Claude signature: %s field %d must be bytes", scope, fieldNum)
+		}
+		bytesValue, err := decodeBytesField(raw, fmt.Sprintf("%s field %d", scope, fieldNum))
+		if err != nil {
+			return err
+		}
+		value = bytesValue
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+	if value == nil {
+		return nil, fmt.Errorf("invalid Claude signature: missing %s field %d", scope, fieldNum)
+	}
+	return value, nil
+}
+
+func walkProtobufFields(msg []byte, visit func(num protowire.Number, typ protowire.Type, raw []byte) error) error {
+	for offset := 0; offset < len(msg); {
+		num, typ, n := protowire.ConsumeTag(msg[offset:])
+		if n < 0 {
+			return fmt.Errorf("invalid Claude signature: malformed protobuf tag: %w", protowire.ParseError(n))
+		}
+		offset += n
+		valueLen := protowire.ConsumeFieldValue(num, typ, msg[offset:])
+		if valueLen < 0 {
+			return fmt.Errorf("invalid Claude signature: malformed protobuf field %d: %w", num, protowire.ParseError(valueLen))
+		}
+		fieldRaw := msg[offset : offset+valueLen]
+		if err := visit(num, typ, fieldRaw); err != nil {
+			return err
+		}
+		offset += valueLen
+	}
+	return nil
+}
+
+func decodeVarintField(raw []byte, label string) (uint64, error) {
+	value, n := protowire.ConsumeVarint(raw)
+	if n < 0 {
+		return 0, fmt.Errorf("invalid Claude signature: failed to decode %s: %w", label, protowire.ParseError(n))
+	}
+	return value, nil
+}
+
+func decodeBytesField(raw []byte, label string) ([]byte, error) {
+	value, n := protowire.ConsumeBytes(raw)
+	if n < 0 {
+		return nil, fmt.Errorf("invalid Claude signature: failed to decode %s: %w", label, protowire.ParseError(n))
+	}
+	return value, nil
+}