5862e2d8d9
Real Claude Code CLI always sends a 2-block system array:
[0] {"type":"text", "text":"x-anthropic-billing-header: cc_version=X.Y.Z.{fp}; cc_entrypoint=cli; cch=00000;"}
[1] {"type":"text", "text":"You are Claude Code...", "cache_control":{...}}
Before this commit, sub2api's mimicry path only produced block [1].
The missing billing block is one of the primary third-party detection
signals Anthropic uses for Claude-Code-scoped OAuth tokens.
New file gateway_billing_block.go ports the fingerprint algorithm
(byte-for-byte from Parrot cc_mimicry.py:compute_fingerprint):
pick chars at positions [4,7,20] of the first user text, then
`sha256(SALT + chars + cc_version)[:3]`.
- claude/constants.go: CLICurrentVersion = "2.1.92" (must match UA)
- gateway_billing_block.go: computeClaudeCodeFingerprint +
buildBillingAttributionBlockJSON + extractFirstUserText
- gateway_service.go: rewriteSystemForNonClaudeCode now emits both
blocks in order; cch=00000 is filled in later by
signBillingHeaderCCH in buildUpstreamRequest.
Downstream compat note: syncBillingHeaderVersion's regex
`cc_version=\d+\.\d+\.\d+` only matches the semver triple,
leaving the `.{fp}` suffix intact when rewriting in buildUpstreamRequest.
99 lines
3.1 KiB
Go
99 lines
3.1 KiB
Go
package service
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import (
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"crypto/sha256"
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"encoding/hex"
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"encoding/json"
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"fmt"
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"github.com/tidwall/gjson"
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)
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// fingerprintSalt 是计算 cc_version 后缀指纹的盐值。
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//
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// 来源：与 Parrot src/transform/cc_mimicry.py 的 FINGERPRINT_SALT 完全一致；
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// 这是真实 Claude Code CLI 抓包推导出的常量，改动会导致 fp 与 CLI 不一致，
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// 进一步触发 Anthropic 的第三方检测。
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const fingerprintSalt = "59cf53e54c78"
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// computeClaudeCodeFingerprint 复刻真实 Claude Code CLI 的 cc_version 指纹算法：
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//
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// 1. 取 messages 中第一条 role=user 的纯文本（首块 text）
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// 2. 取该文本的第 4、7、20 字符（不足以 '0' 补齐）
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// 3. SHA256(SALT + chars + cc_version) 取 hex 前 3 字符
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//
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// 算法来自 Parrot src/transform/cc_mimicry.py:compute_fingerprint，与官方 CLI 字节对齐。
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// 任何偏差都会导致 cc_version=X.Y.Z.{fp} 在上游侧与真实 CLI 不一致。
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func computeClaudeCodeFingerprint(body []byte, version string) string {
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firstText := extractFirstUserText(body)
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indices := []int{4, 7, 20}
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chars := make([]byte, 0, 3)
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for _, i := range indices {
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if i < len(firstText) {
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chars = append(chars, firstText[i])
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} else {
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chars = append(chars, '0')
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}
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}
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sum := sha256.Sum256([]byte(fingerprintSalt + string(chars) + version))
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return hex.EncodeToString(sum[:])[:3]
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}
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// extractFirstUserText 提取 messages 中第一条 user 消息的首段 text 内容。
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// 兼容 string 和 []block 两种 content 格式。
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func extractFirstUserText(body []byte) string {
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messages := gjson.GetBytes(body, "messages")
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if !messages.IsArray() {
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return ""
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}
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first := ""
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messages.ForEach(func(_, msg gjson.Result) bool {
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if msg.Get("role").String() != "user" {
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return true
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}
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content := msg.Get("content")
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if content.Type == gjson.String {
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first = content.String()
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return false
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}
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if content.IsArray() {
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content.ForEach(func(_, block gjson.Result) bool {
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if block.Get("type").String() == "text" {
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first = block.Get("text").String()
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return false
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}
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return true
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})
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return false
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}
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return false
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})
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return first
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}
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// buildBillingAttributionBlockJSON 构造 system 数组的 billing attribution block。
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//
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// 形态严格对齐真实 Claude Code CLI：
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//
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// {"type":"text","text":"x-anthropic-billing-header: cc_version=2.1.92.{fp}; cc_entrypoint=cli; cch=00000;"}
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//
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// cch=00000 是签名占位符，由 signBillingHeaderCCH 在 buildUpstreamRequest 阶段
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// 替换为基于完整 body 的 xxhash64 5 位十六进制摘要。
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//
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// 此 block 不带 cache_control（与真实 CLI 一致；cache breakpoint 由后续的
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// Claude Code prompt block 承担）。
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func buildBillingAttributionBlockJSON(body []byte, cliVersion string) ([]byte, error) {
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if cliVersion == "" {
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return nil, fmt.Errorf("cliVersion required")
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}
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fp := computeClaudeCodeFingerprint(body, cliVersion)
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text := fmt.Sprintf(
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"x-anthropic-billing-header: cc_version=%s.%s; cc_entrypoint=cli; cch=00000;",
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cliVersion, fp,
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)
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return json.Marshal(map[string]string{
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"type": "text",
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"text": text,
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})
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}
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