mirror of
https://github.com/shadowsocks/ShadowsocksX-NG.git
synced 2026-11-14 02:04:13 +00:00
280 lines
11 KiB
Swift
280 lines
11 KiB
Swift
import Foundation
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/// SIP002 `ss://` URI 模型（https://shadowsocks.org/doc/sip002.html）。
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/// 插件字段持 SIP003 `SS_PLUGIN_OPTIONS` 形态的原样字符串（如
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/// `mode=websocket;host=example.com`）：URI 编解码只做 RFC 3986 百分号编码层，
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/// 反斜杠转义按原样透传（插件自解），往返保持 `plugin=name;opts` 逐字节同构。
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struct SsUri: Equatable, Sendable {
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var method: String
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var password: String
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var host: String
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var port: Int
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/// 插件程序名；无插件为 `nil`。
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var pluginProgram: String?
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/// 插件参数（SS_PLUGIN_OPTIONS 原样形态）；无插件或仅有程序名为 `nil`。
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var pluginOptions: String?
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/// 备注（URI fragment）；缺失或空为 `nil`。
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var remark: String?
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init(
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method: String,
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password: String,
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host: String,
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port: Int,
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pluginProgram: String? = nil,
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pluginOptions: String? = nil,
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remark: String? = nil
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) {
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self.method = method
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self.password = password
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self.host = host
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self.port = port
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self.pluginProgram = pluginProgram
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self.pluginOptions = pluginOptions
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self.remark = remark
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}
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}
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/// 解码失败原因：输入不是可解析的 `ss://` URI。
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enum SsUriError: Error, Equatable {
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/// 不以 `ss://` 开头。
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case notSsUri
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/// scheme 正确但结构或字段非法（缺端口、base64 解不开、端口越界等）。
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case malformed(detail: String)
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}
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// MARK: - 解码
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extension SsUri {
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/// 解码单个 URI 行。同时接受：
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/// - SIP002 形态：`ss://userinfo@host:port/?plugin=…#tag`（userinfo 为
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/// base64url(`method:password`) 或百分号编码明文——AEAD-2022 规定明文）。
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/// - Legacy 兼容形态：`ss://base64(method:password@host:port)#tag`（无 `@`，
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/// 密码明文，非 RFC 3986）。
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static func decode(_ rawInput: String) throws -> SsUri {
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let input = rawInput.trimmingCharacters(in: .whitespacesAndNewlines)
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let schemePrefix = "ss://"
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guard input.lowercased().hasPrefix(schemePrefix) else { throw SsUriError.notSsUri }
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var rest = String(input.dropFirst(schemePrefix.count))
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// fragment（备注）：base64 字母表与百分号编码都不含裸 `#`，取首个裸 `#` 安全。
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var remark: String?
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if let hashIndex = rest.firstIndex(of: "#") {
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remark = percentDecode(String(rest[rest.index(after: hashIndex)...]))
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rest = String(rest[..<hashIndex])
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}
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if rest.contains("@") {
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return try decodeSIP002(rest, remark: remark)
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}
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return try decodeLegacy(rest, remark: remark)
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}
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/// SIP002 形态：在最后一个 `@` 处分离 userinfo 与 host:port（+query）。
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private static func decodeSIP002(_ rest: String, remark: String?) throws -> SsUri {
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guard let atSign = rest.lastIndex(of: "@") else {
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throw SsUriError.malformed(detail: "missing userinfo separator")
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}
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let userInfo = String(rest[..<atSign])
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var hostPort = String(rest[rest.index(after: atSign)...])
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var query: String?
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if let queryIndex = hostPort.firstIndex(of: "?") {
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query = String(hostPort[hostPort.index(after: queryIndex)...])
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hostPort = String(hostPort[..<queryIndex])
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}
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hostPort = hostPort.trimmingCharacters(in: CharacterSet(charactersIn: "/"))
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let (host, port) = try parseHostPort(hostPort)
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let (method, password) = try parseUserInfo(userInfo)
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let plugin = parsePluginQuery(query)
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return SsUri(
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method: method, password: password, host: host, port: port,
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pluginProgram: plugin?.program, pluginOptions: plugin?.options, remark: remark)
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}
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/// userinfo 解析：先按 base64url（补齐 padding、兼容两种字母表）；解不出或
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/// 不含分隔冒号时回退百分号编码明文（SIP022 形态）。
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private static func parseUserInfo(_ userInfo: String) throws -> (String, String) {
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if let decoded = base64FlexibleDecode(userInfo), let separator = decoded.firstIndex(of: ":") {
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let method = String(decoded[..<separator])
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let password = String(decoded[decoded.index(after: separator)...])
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guard !method.isEmpty, !password.isEmpty else {
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throw SsUriError.malformed(detail: "method or password is empty")
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}
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return (method, password)
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}
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guard let plain = percentDecode(userInfo), let separator = plain.firstIndex(of: ":") else {
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throw SsUriError.malformed(
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detail: "userinfo is neither base64 nor percent-encoded method:password")
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}
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let method = String(plain[..<separator])
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let password = String(plain[plain.index(after: separator)...])
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guard !method.isEmpty, !password.isEmpty else {
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throw SsUriError.malformed(detail: "method or password is empty")
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}
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return (method, password)
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}
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/// Legacy 形态：整体 base64 → `method:password@host:port`。密码为明文
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/// （可能含 `@` 与 `:`），故 host:port 侧用「最后一个 @」切分。
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private static func decodeLegacy(_ rest: String, remark: String?) throws -> SsUri {
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let trimmed = rest.trimmingCharacters(in: CharacterSet(charactersIn: "/"))
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guard let decoded = base64FlexibleDecode(trimmed) else {
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throw SsUriError.malformed(detail: "legacy payload is not valid base64")
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}
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guard let atSign = decoded.lastIndex(of: "@") else {
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throw SsUriError.malformed(detail: "legacy payload missing @")
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}
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let credentials = String(decoded[..<atSign])
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let hostPort = String(decoded[decoded.index(after: atSign)...])
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guard let colon = credentials.firstIndex(of: ":") else {
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throw SsUriError.malformed(detail: "legacy payload missing method separator")
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}
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let (host, port) = try parseHostPort(hostPort)
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let method = String(credentials[..<colon])
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let password = String(credentials[credentials.index(after: colon)...])
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guard !method.isEmpty, !password.isEmpty else {
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throw SsUriError.malformed(detail: "method or password is empty")
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}
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return SsUri(
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method: method,
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password: password,
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host: host, port: port, remark: remark)
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}
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/// host:port 解析：IPv6 必须为方括号形态；否则以最后一个冒号分离端口。
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private static func parseHostPort(_ hostPort: String) throws -> (String, Int) {
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let host: String
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let portText: String
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if hostPort.hasPrefix("[") {
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guard let closing = hostPort.firstIndex(of: "]") else {
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throw SsUriError.malformed(detail: "unclosed IPv6 bracket")
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}
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host = String(hostPort[hostPort.index(hostPort.startIndex, offsetBy: 1)..<closing])
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let remainder = hostPort[hostPort.index(after: closing)...]
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guard remainder.hasPrefix(":") else {
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throw SsUriError.malformed(detail: "missing port after IPv6 bracket")
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}
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portText = String(remainder.dropFirst())
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} else {
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guard let colon = hostPort.lastIndex(of: ":") else {
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throw SsUriError.malformed(detail: "missing port")
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}
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host = String(hostPort[..<colon])
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portText = String(hostPort[hostPort.index(after: colon)...])
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}
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guard let port = Int(portText), (1...65_535).contains(port) else {
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throw SsUriError.malformed(detail: "invalid port \(portText)")
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}
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guard !host.isEmpty else { throw SsUriError.malformed(detail: "empty host") }
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return (host, port)
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}
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/// query 中的 `plugin` 参数：百分号解码后为 `name;opts`，首个 `;` 切分；
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/// opts 原样保留。`plugin=` 空值视为无插件。
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private static func parsePluginQuery(
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_ query: String?
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) -> (program: String, options: String?)? {
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guard let query else { return nil }
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var pluginValue: String?
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for pair in query.split(separator: "&") {
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let name: String
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let value: String
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if let equals = pair.firstIndex(of: "=") {
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name = String(pair[..<equals])
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value = String(pair[pair.index(after: equals)...])
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} else {
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name = String(pair)
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value = ""
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}
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if percentDecode(name) == "plugin" { pluginValue = percentDecode(value) }
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}
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guard let pluginValue, !pluginValue.isEmpty else { return nil }
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let program: String
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let options: String?
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if let semicolon = pluginValue.firstIndex(of: ";") {
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program = String(pluginValue[..<semicolon])
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let rest = String(pluginValue[pluginValue.index(after: semicolon)...])
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options = rest.isEmpty ? nil : rest
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} else {
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program = pluginValue
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options = nil
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}
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guard !program.isEmpty else { return nil }
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return (program, options)
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}
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}
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// MARK: - 编码
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extension SsUri {
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/// 规范 SIP002 形态：`ss://userinfo@host:port[/?plugin=…][#remark]`。
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/// AEAD-2022（SIP022，`2022-blake3-*`）按规范用百分号编码明文 userinfo，
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/// 其余用 base64url（无 padding）。
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func encode() -> String {
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let userInfo: String
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if method.hasPrefix("2022-blake3-") {
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userInfo = "\(Self.percentEncode(method)):\(Self.percentEncode(password))"
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} else {
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userInfo = Self.base64URLEncodeNoPadding("\(method):\(password)")
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}
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var uri = "ss://\(userInfo)@\(encodedHost):\(port)"
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if let program = pluginProgram {
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let pluginValue = pluginOptions.map { "\(program);\($0)" } ?? program
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uri += "/?plugin=\(Self.percentEncode(pluginValue))"
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}
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if let remark, !remark.isEmpty {
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uri += "#\(Self.percentEncode(remark))"
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}
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return uri
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}
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/// 解码得到的 IPv6（裸冒号形态）编码时重新加方括号。
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private var encodedHost: String {
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host.contains(":") ? "[\(host)]" : host
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}
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}
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// MARK: - base64 与百分号编码工具
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extension SsUri {
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/// base64url 无 padding（SIP002 userinfo 的规范形态）。
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static func base64URLEncodeNoPadding(_ text: String) -> String {
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Data(text.utf8)
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.base64EncodedString()
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.replacingOccurrences(of: "+", with: "-")
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.replacingOccurrences(of: "/", with: "_")
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.replacingOccurrences(of: "=", with: "")
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}
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/// 宽容 base64 解码：兼容标准/url-safe 两种字母表与缺失 padding
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/// （社区分享链接普遍省略 padding）。
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static func base64FlexibleDecode(_ text: String) -> String? {
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var normalized =
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text
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.replacingOccurrences(of: "-", with: "+")
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.replacingOccurrences(of: "_", with: "/")
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.replacingOccurrences(of: "\n", with: "")
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.replacingOccurrences(of: "\r", with: "")
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.trimmingCharacters(in: .whitespaces)
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let remainder = normalized.count % 4
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if remainder == 1 { return nil } // 不可能是合法 base64 长度
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if remainder > 0 { normalized.append(String(repeating: "=", count: 4 - remainder)) }
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guard let data = Data(base64Encoded: normalized) else { return nil }
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return String(data: data, encoding: .utf8)
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}
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/// 百分号编码：仅保留 RFC 3986 unreserved（字母数字与 `-._~`），其余全部
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/// 转义——与官方示例的 `obfs-local%3Bobfs%3Dhttp` 形态一致。
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static func percentEncode(_ text: String) -> String {
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let allowed = CharacterSet(
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charactersIn: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-._~")
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return text.addingPercentEncoding(withAllowedCharacters: allowed) ?? text
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}
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private static func percentDecode(_ text: String) -> String? {
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text.removingPercentEncoding
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}
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}
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