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Diffstat (limited to 'src/auth.zig')
| -rw-r--r-- | src/auth.zig | 954 |
1 files changed, 954 insertions, 0 deletions
diff --git a/src/auth.zig b/src/auth.zig new file mode 100644 index 0000000..f70b031 --- /dev/null +++ b/src/auth.zig @@ -0,0 +1,954 @@ +//! Provider authentication: named auth sessions resolved into request-ready +//! credentials before a provider stream opens. +//! +//! A provider names the auth session it uses (`auth = "<name>"`); core +//! resolves that session into a `ResolvedCredential` (a bearer/api-key value, +//! an optional dynamic `base_url`, and optional auth-derived request headers). +//! This covers three families with one configuration shape: +//! +//! - `api_key` — static key from a literal or an environment variable. +//! - `oauth_device` — OAuth 2.0 device-authorization flow. Two dialects: +//! * `token` — standard device flow (GitHub Copilot). The poll endpoint +//! returns the OAuth token response directly. +//! * `codex` — OpenAI Codex device flow. The poll endpoint returns an +//! authorization code plus a server-generated PKCE verifier; core +//! exchanges those at `token_url` for `{access,refresh,id}_token`. +//! +//! This module owns the *mechanism* (config types, the persisted token shape, +//! and — added incrementally — the HTTP flows and refresh lifecycle). It is +//! UI- and filesystem-policy-agnostic: token storage takes a directory path, +//! and interactive device-code prompts are delivered through a caller-supplied +//! `Presenter`. That keeps libpanto reusable while the embedder owns token +//! storage policy and how a device code is shown to the user. + +const std = @import("std"); +const builtin = @import("builtin"); +const Io = std.Io; +const config_mod = @import("config.zig"); +const http = @import("http_helper.zig"); + +/// A single request header. Re-exported from `config.zig` so callers can +/// build auth-derived headers and provider `extra_headers` from one type. +pub const Header = config_mod.Header; + +// =========================================================================== +// Auth configuration (parsed from `[auth.<name>]`) +// =========================================================================== + +pub const AuthType = enum { api_key, oauth_device }; + +/// Device-flow completion shape. See the module doc. +pub const DeviceDialect = enum { token, codex }; + +/// Wire encoding for the `token` dialect's device-code / poll request bodies. +pub const TokenRequestFormat = enum { form, json }; + +/// Static API-key auth. `key` is the resolved credential — a literal, or the +/// result of `${env:VAR}`-style substitution performed by the embedder. An +/// absent/empty key means unresolved; providers using such a session are +/// omitted from the active config (export the key and they reappear). +pub const ApiKeyAuth = struct { + key: ?[]const u8 = null, +}; + +/// A secondary token exchange run after the durable OAuth token is obtained +/// (GitHub Copilot's `/copilot_internal/v2/token`). The exchange result — +/// not the OAuth token — becomes the request credential, and may also +/// override the provider `base_url`. +pub const ExchangeConfig = struct { + method: []const u8 = "GET", + url: []const u8, + /// Which stored token to send as the exchange request's bearer. + bearer: BearerSource = .oauth_access_token, + /// Dotted JSON path to the credential in the exchange response. + token_json_path: []const u8 = "token", + /// Dotted JSON path to the credential's unix-seconds expiry, if any. + expires_at_json_path: ?[]const u8 = null, + /// Dotted JSON path to a dynamic `base_url` in the exchange response. + base_url_json_path: ?[]const u8 = null, + + pub const BearerSource = enum { oauth_access_token }; +}; + +/// OAuth 2.0 device-authorization auth. +pub const OAuthDeviceAuth = struct { + dialect: DeviceDialect = .token, + client_id: []const u8, + /// Endpoint that issues the device/user code. + device_code_url: []const u8, + /// `token` dialect: poll-for-token and refresh endpoint. + /// `codex` dialect: authorization-code exchange and refresh endpoint. + token_url: []const u8, + /// `codex` dialect: endpoint polled for the authorization code. + device_poll_url: ?[]const u8 = null, + /// Browser URL shown to the user (codex). For the `token` dialect the + /// verification URI comes from the device-code response. + verification_url: ?[]const u8 = null, + scope: ?[]const u8 = null, + /// Request encoding for the `token` dialect device-code / poll bodies. + token_request_format: TokenRequestFormat = .form, + /// `codex` dialect: redirect URI sent in the code exchange. + redirect_uri: ?[]const u8 = null, + /// `codex` dialect: JWT claim (on the id_token) holding the account id, + /// e.g. `https://api.openai.com/auth`. When set, the resolver extracts an + /// account id and emits it as a header (see provider wiring). + account_id_jwt_claim: ?[]const u8 = null, + /// Optional post-login token exchange (Copilot). + exchange: ?ExchangeConfig = null, +}; + +/// One named auth session's configuration. The union tag mirrors the TOML +/// `type` field. +pub const AuthConfig = union(AuthType) { + api_key: ApiKeyAuth, + oauth_device: OAuthDeviceAuth, +}; + +// =========================================================================== +// Persisted token state (`<auth_dir>/<name>.json`) +// =========================================================================== + +/// Durable auth state for one session. Only the fields relevant to the auth +/// type are populated. Treat the on-disk file like a password. +pub const TokenSet = struct { + /// `"api_key"` | `"oauth_device"` — records which family wrote the file. + type: []const u8 = "oauth_device", + /// Durable OAuth access token (the `ghu_...` for Copilot; the JWT access + /// token for Codex). + access_token: ?[]const u8 = null, + refresh_token: ?[]const u8 = null, + id_token: ?[]const u8 = null, + /// Unix-seconds expiry of `access_token` (when known; OAuth `expires_in` + /// or a JWT `exp`). Null for tokens with no intrinsic expiry (Copilot's + /// durable `ghu_` token). + expires_at: ?i64 = null, + /// Account id derived from the id_token (Codex `chatgpt-account-id`). + account_id: ?[]const u8 = null, + /// Result of the secondary exchange (Copilot short-lived API token). + exchange: ?ExchangeToken = null, + + pub const ExchangeToken = struct { + token: []const u8, + /// Unix-seconds expiry of the exchanged token. + expires_at: ?i64 = null, + /// Dynamic base_url returned by the exchange, if any. + base_url: ?[]const u8 = null, + }; +}; + +// =========================================================================== +// Resolved credential (handed to the provider for one turn) +// =========================================================================== + +/// The request-ready output of resolving an auth session: the secret to place +/// in the provider's auth header, plus any dynamic base_url and auth-derived +/// headers. The embedder injects these into the active `ProviderConfig`. +pub const ResolvedCredential = struct { + /// Value for the provider auth header (the bearer / x-api-key value). + api_key: []const u8, + /// Overrides the provider's configured `base_url` when present (e.g. + /// Copilot's `endpoints.api`). + base_url_override: ?[]const u8 = null, + /// Auth-derived headers (e.g. `chatgpt-account-id`) to merge onto the + /// provider's request. + extra_headers: []const Header = &.{}, +}; + +// =========================================================================== +// Token storage (`<auth_dir>/<name>.json`) +// =========================================================================== + +/// A parsed `TokenSet` plus the arena owning its strings. Call `deinit`. +pub const ParsedTokenSet = std.json.Parsed(TokenSet); + +/// Owner-only file permissions for token files (POSIX 0o600). On Windows the +/// platform `Permissions` enum has no mode, so fall back to its default. +fn tokenFilePermissions() Io.File.Permissions { + if (builtin.os.tag == .windows) return .default_file; + return Io.File.Permissions.fromMode(0o600); +} + +/// Load and parse `<auth_dir>/<name>.json`. Returns null if the file does not +/// exist. The caller owns the result and must `deinit` it. +pub fn loadTokenSet( + allocator: std.mem.Allocator, + io: Io, + auth_dir: []const u8, + name: []const u8, +) !?ParsedTokenSet { + const fname = try std.fmt.allocPrint(allocator, "{s}.json", .{name}); + defer allocator.free(fname); + + var dir = Io.Dir.cwd().openDir(io, auth_dir, .{}) catch |err| switch (err) { + error.FileNotFound => return null, + else => return err, + }; + defer dir.close(io); + + const bytes = dir.readFileAlloc(io, fname, allocator, .limited(1 << 20)) catch |err| switch (err) { + error.FileNotFound => return null, + else => return err, + }; + defer allocator.free(bytes); + + return try std.json.parseFromSlice(TokenSet, allocator, bytes, .{ + .ignore_unknown_fields = true, + .allocate = .alloc_always, + }); +} + +/// Serialize and write `ts` to `<auth_dir>/<name>.json` with owner-only +/// permissions, creating `auth_dir` if needed. Null optional fields are +/// omitted to keep the file tidy. +pub fn saveTokenSet( + allocator: std.mem.Allocator, + io: Io, + auth_dir: []const u8, + name: []const u8, + ts: TokenSet, +) !void { + Io.Dir.cwd().createDirPath(io, auth_dir) catch |err| switch (err) { + error.PathAlreadyExists => {}, + else => return err, + }; + + const json = try std.json.Stringify.valueAlloc(allocator, ts, .{ + .emit_null_optional_fields = false, + .whitespace = .indent_2, + }); + defer allocator.free(json); + + const fname = try std.fmt.allocPrint(allocator, "{s}.json", .{name}); + defer allocator.free(fname); + + var dir = try Io.Dir.cwd().openDir(io, auth_dir, .{}); + defer dir.close(io); + try dir.writeFile(io, .{ + .sub_path = fname, + .data = json, + .flags = .{ .permissions = tokenFilePermissions() }, + }); +} + +/// Delete `<auth_dir>/<name>.json`. Returns true if a file was removed, false +/// if it did not exist (idempotent logout). +pub fn deleteTokenSet( + allocator: std.mem.Allocator, + io: Io, + auth_dir: []const u8, + name: []const u8, +) !bool { + const fname = try std.fmt.allocPrint(allocator, "{s}.json", .{name}); + defer allocator.free(fname); + var dir = Io.Dir.cwd().openDir(io, auth_dir, .{}) catch |err| switch (err) { + error.FileNotFound => return false, + else => return err, + }; + defer dir.close(io); + dir.deleteFile(io, fname) catch |err| switch (err) { + error.FileNotFound => return false, + else => return err, + }; + return true; +} + +// =========================================================================== +// OAuth device flow +// =========================================================================== + +pub const AuthError = error{ + /// No persisted token and no interactive presenter to run a login. + AuthLoginRequired, + /// The OAuth endpoint returned an error (denied, expired, malformed). + AuthFlowFailed, + /// The device-flow poll exceeded its deadline. + AuthLoginTimeout, + /// The configured auth could not be resolved into a credential. + AuthUnresolved, +}; + +/// The device-code prompt shown to the user. The embedder renders this +/// (a verification URL + a short user code) however suits its UI. +pub const DeviceCodePrompt = struct { + verification_uri: []const u8, + user_code: []const u8, + /// Seconds until the code expires (0 if the endpoint didn't say). + expires_in: i64 = 0, +}; + +/// Caller-supplied UI hook for interactive device login. `onDeviceCode` is +/// called once with the prompt; `onStatus` (optional) receives progress text. +pub const Presenter = struct { + ptr: *anyopaque, + vtable: *const VTable, + + pub const VTable = struct { + on_device_code: *const fn (ptr: *anyopaque, prompt: DeviceCodePrompt) void, + on_status: ?*const fn (ptr: *anyopaque, msg: []const u8) void = null, + }; + + fn deviceCode(self: Presenter, prompt: DeviceCodePrompt) void { + self.vtable.on_device_code(self.ptr, prompt); + } + fn status(self: Presenter, msg: []const u8) void { + if (self.vtable.on_status) |f| f(self.ptr, msg); + } +}; + +/// The OAuth token-endpoint response, fields borrowed from an arena. +pub const OAuthTokens = struct { + access_token: []const u8, + refresh_token: ?[]const u8 = null, + id_token: ?[]const u8 = null, + /// Seconds-to-live from `expires_in`, if present. + expires_in: ?i64 = null, +}; + +/// Identifiers needed to poll a started device authorization. +const DeviceAuth = struct { + /// `token` dialect poll parameter. + device_code: ?[]const u8 = null, + /// `codex` dialect poll parameter. + device_auth_id: ?[]const u8 = null, + user_code: []const u8, + verification_uri: []const u8, + interval_secs: u32 = 5, + expires_in: i64 = 0, +}; + +/// `application/x-www-form-urlencoded` body from name/value pairs. Values are +/// percent-encoded (unreserved chars pass through). Allocated in `arena`. +fn formEncode(arena: std.mem.Allocator, pairs: []const [2][]const u8) ![]u8 { + var out: std.ArrayList(u8) = .empty; + for (pairs, 0..) |kv, i| { + if (i != 0) try out.append(arena, '&'); + try percentEncode(arena, &out, kv[0]); + try out.append(arena, '='); + try percentEncode(arena, &out, kv[1]); + } + return out.toOwnedSlice(arena); +} + +fn percentEncode(arena: std.mem.Allocator, out: *std.ArrayList(u8), s: []const u8) !void { + for (s) |c| { + const unreserved = (c >= 'A' and c <= 'Z') or (c >= 'a' and c <= 'z') or + (c >= '0' and c <= '9') or c == '-' or c == '.' or c == '_' or c == '~'; + if (unreserved) { + try out.append(arena, c); + } else { + try out.print(arena, "%{X:0>2}", .{c}); + } + } +} + +/// Build the device-code / token request body in the dialect's encoding. +fn encodeBody( + arena: std.mem.Allocator, + format: TokenRequestFormat, + pairs: []const [2][]const u8, +) !struct { body: []u8, content_type: []const u8 } { + switch (format) { + .form => return .{ .body = try formEncode(arena, pairs), .content_type = "application/x-www-form-urlencoded" }, + .json => { + var aw: std.Io.Writer.Allocating = .init(arena); + var s: std.json.Stringify = .{ .writer = &aw.writer }; + try s.beginObject(); + for (pairs) |kv| { + try s.objectField(kv[0]); + try s.write(kv[1]); + } + try s.endObject(); + return .{ .body = aw.written(), .content_type = "application/json" }; + }, + } +} + +/// Request a device/user code. `headers` are the client-identity headers +/// (the provider's `extra_headers`) sent on every auth HTTP call. Allocates +/// the result into `arena`. +fn requestDeviceAuth( + arena: std.mem.Allocator, + client: *std.http.Client, + oauth: OAuthDeviceAuth, + headers: []const Header, +) !DeviceAuth { + const enc = switch (oauth.dialect) { + // GitHub: `client_id` (+ optional scope), in the configured encoding. + .token => try encodeBody(arena, oauth.token_request_format, blk: { + if (oauth.scope) |sc| { + break :blk &[_][2][]const u8{ .{ "client_id", oauth.client_id }, .{ "scope", sc } }; + } else break :blk &[_][2][]const u8{.{ "client_id", oauth.client_id }}; + }), + // Codex: JSON `{client_id}`. + .codex => try encodeBody(arena, .json, &.{.{ "client_id", oauth.client_id }}), + }; + + const resp = try http.request(arena, client, .POST, oauth.device_code_url, .{ + .headers = headers, + .body = enc.body, + .content_type = enc.content_type, + }); + if (!resp.ok()) return AuthError.AuthFlowFailed; + + const parsed = std.json.parseFromSlice(std.json.Value, arena, resp.body, .{}) catch + return AuthError.AuthFlowFailed; + const v = parsed.value; + + const user_code = http.jsonStringAtPath(v, "user_code") orelse + http.jsonStringAtPath(v, "usercode") orelse return AuthError.AuthFlowFailed; + const interval: u32 = blk: { + if (http.jsonIntAtPath(v, "interval")) |iv| break :blk @intCast(@max(iv, 1)); + // Codex returns interval as a string. + if (http.jsonStringAtPath(v, "interval")) |is| { + if (std.fmt.parseInt(i64, is, 10) catch null) |iv| break :blk @intCast(@max(iv, 1)); + } + break :blk 5; + }; + const verification_uri = switch (oauth.dialect) { + .token => http.jsonStringAtPath(v, "verification_uri") orelse + http.jsonStringAtPath(v, "verification_uri_complete") orelse return AuthError.AuthFlowFailed, + .codex => oauth.verification_url orelse return AuthError.AuthFlowFailed, + }; + return .{ + .device_code = http.jsonStringAtPath(v, "device_code"), + .device_auth_id = http.jsonStringAtPath(v, "device_auth_id"), + .user_code = user_code, + .verification_uri = verification_uri, + .interval_secs = interval, + .expires_in = http.jsonIntAtPath(v, "expires_in") orelse 0, + }; +} + +const PollResult = union(enum) { + pending, + done: OAuthTokens, +}; + +/// Poll once for completion. Allocates any returned tokens into `arena`. +fn pollOnce( + arena: std.mem.Allocator, + client: *std.http.Client, + oauth: OAuthDeviceAuth, + da: DeviceAuth, + headers: []const Header, +) !PollResult { + switch (oauth.dialect) { + .token => { + const enc = try encodeBody(arena, oauth.token_request_format, &.{ + .{ "client_id", oauth.client_id }, + .{ "device_code", da.device_code orelse return AuthError.AuthFlowFailed }, + .{ "grant_type", "urn:ietf:params:oauth:grant-type:device_code" }, + }); + const resp = try http.request(arena, client, .POST, oauth.token_url, .{ + .headers = headers, + .body = enc.body, + .content_type = enc.content_type, + }); + const parsed = std.json.parseFromSlice(std.json.Value, arena, resp.body, .{}) catch + return AuthError.AuthFlowFailed; + const v = parsed.value; + if (http.jsonStringAtPath(v, "error")) |e| { + if (std.mem.eql(u8, e, "authorization_pending") or std.mem.eql(u8, e, "slow_down")) + return .pending; + return AuthError.AuthFlowFailed; + } + const tokens = parseOAuthTokens(v) orelse return AuthError.AuthFlowFailed; + return .{ .done = tokens }; + }, + .codex => { + const poll_url = oauth.device_poll_url orelse return AuthError.AuthFlowFailed; + const enc = try encodeBody(arena, .json, &.{ + .{ "device_auth_id", da.device_auth_id orelse return AuthError.AuthFlowFailed }, + .{ "user_code", da.user_code }, + }); + const resp = try http.request(arena, client, .POST, poll_url, .{ + .headers = headers, + .body = enc.body, + .content_type = enc.content_type, + }); + // 403/404 => still pending (reference behavior). + if (resp.status == 403 or resp.status == 404) return .pending; + if (!resp.ok()) return AuthError.AuthFlowFailed; + const parsed = std.json.parseFromSlice(std.json.Value, arena, resp.body, .{}) catch + return AuthError.AuthFlowFailed; + const code = http.jsonStringAtPath(parsed.value, "authorization_code") orelse return .pending; + const verifier = http.jsonStringAtPath(parsed.value, "code_verifier") orelse return AuthError.AuthFlowFailed; + // Exchange the authorization code + server-generated PKCE verifier. + const tokens = try exchangeCode(arena, client, oauth, code, verifier, headers); + return .{ .done = tokens }; + }, + } +} + +/// Codex authorization-code exchange at the token endpoint. +fn exchangeCode( + arena: std.mem.Allocator, + client: *std.http.Client, + oauth: OAuthDeviceAuth, + code: []const u8, + verifier: []const u8, + headers: []const Header, +) !OAuthTokens { + const redirect = oauth.redirect_uri orelse "https://auth.openai.com/deviceauth/callback"; + const enc = try encodeBody(arena, .form, &.{ + .{ "grant_type", "authorization_code" }, + .{ "client_id", oauth.client_id }, + .{ "code", code }, + .{ "code_verifier", verifier }, + .{ "redirect_uri", redirect }, + }); + const resp = try http.request(arena, client, .POST, oauth.token_url, .{ + .headers = headers, + .body = enc.body, + .content_type = enc.content_type, + }); + if (!resp.ok()) return AuthError.AuthFlowFailed; + const parsed = std.json.parseFromSlice(std.json.Value, arena, resp.body, .{}) catch + return AuthError.AuthFlowFailed; + return parseOAuthTokens(parsed.value) orelse AuthError.AuthFlowFailed; +} + +/// Refresh an access token. Allocates into `arena`. +pub fn refreshTokens( + arena: std.mem.Allocator, + client: *std.http.Client, + oauth: OAuthDeviceAuth, + refresh_token: []const u8, + headers: []const Header, +) !OAuthTokens { + const enc = try encodeBody(arena, .form, &.{ + .{ "grant_type", "refresh_token" }, + .{ "refresh_token", refresh_token }, + .{ "client_id", oauth.client_id }, + }); + const resp = try http.request(arena, client, .POST, oauth.token_url, .{ + .headers = headers, + .body = enc.body, + .content_type = enc.content_type, + }); + if (!resp.ok()) return AuthError.AuthFlowFailed; + const parsed = std.json.parseFromSlice(std.json.Value, arena, resp.body, .{}) catch + return AuthError.AuthFlowFailed; + return parseOAuthTokens(parsed.value) orelse AuthError.AuthFlowFailed; +} + +/// Pluck an `OAuthTokens` out of a parsed token response. Null if no +/// `access_token`. Borrows from the parsed value. +fn parseOAuthTokens(v: std.json.Value) ?OAuthTokens { + const access = http.jsonStringAtPath(v, "access_token") orelse return null; + return .{ + .access_token = access, + .refresh_token = http.jsonStringAtPath(v, "refresh_token"), + .id_token = http.jsonStringAtPath(v, "id_token"), + .expires_in = http.jsonIntAtPath(v, "expires_in"), + }; +} + +/// Run the full interactive device login: request a code, present it, then +/// poll until authorized (or the deadline passes). Allocates the resulting +/// tokens into `arena`. +pub fn login( + arena: std.mem.Allocator, + io: Io, + client: *std.http.Client, + oauth: OAuthDeviceAuth, + presenter: Presenter, + headers: []const Header, +) !OAuthTokens { + const da = try requestDeviceAuth(arena, client, oauth, headers); + presenter.deviceCode(.{ + .verification_uri = da.verification_uri, + .user_code = da.user_code, + .expires_in = da.expires_in, + }); + presenter.status("waiting for authorization…"); + + const start_ns = std.Io.Clock.now(.real, io).nanoseconds; + const deadline_ns = start_ns + 15 * std.time.ns_per_min; + while (true) { + io.sleep(.fromSeconds(@intCast(da.interval_secs)), .real) catch {}; + const result = try pollOnce(arena, client, oauth, da, headers); + switch (result) { + .pending => {}, + .done => |toks| return toks, + } + if (std.Io.Clock.now(.real, io).nanoseconds >= deadline_ns) return AuthError.AuthLoginTimeout; + } +} + +// =========================================================================== +// Secondary token exchange (Copilot) +// =========================================================================== + +/// Run the configured exchange (Copilot's `/v2/token`) using `bearer` as the +/// request bearer. Returns the exchanged token + optional expiry/base_url, +/// allocated into `arena`. +pub fn runExchange( + arena: std.mem.Allocator, + client: *std.http.Client, + exchange: ExchangeConfig, + bearer: []const u8, + headers: []const Header, +) !TokenSet.ExchangeToken { + const auth_value = try std.fmt.allocPrint(arena, "Bearer {s}", .{bearer}); + var hdrs: std.ArrayList(Header) = .empty; + try hdrs.append(arena, .{ .name = "authorization", .value = auth_value }); + for (headers) |h| try hdrs.append(arena, h); + + const method: http.Method = if (std.ascii.eqlIgnoreCase(exchange.method, "POST")) .POST else .GET; + const resp = try http.request(arena, client, method, exchange.url, .{ .headers = hdrs.items }); + if (!resp.ok()) return AuthError.AuthFlowFailed; + + const parsed = std.json.parseFromSlice(std.json.Value, arena, resp.body, .{}) catch + return AuthError.AuthFlowFailed; + const v = parsed.value; + const token = http.jsonStringAtPath(v, exchange.token_json_path) orelse return AuthError.AuthFlowFailed; + return .{ + .token = token, + .expires_at = if (exchange.expires_at_json_path) |p| http.jsonIntAtPath(v, p) else null, + .base_url = if (exchange.base_url_json_path) |p| http.jsonStringAtPath(v, p) else null, + }; +} + +// =========================================================================== +// JWT + credential building (pure) +// =========================================================================== + +/// Decode a JWT's payload (the middle segment) into a parsed JSON value. +/// Returns null if the token is malformed. Caller owns the result. +pub fn decodeJwtPayload(allocator: std.mem.Allocator, token: []const u8) ?std.json.Parsed(std.json.Value) { + var it = std.mem.splitScalar(u8, token, '.'); + _ = it.next() orelse return null; // header + const payload_b64 = it.next() orelse return null; + if (it.next() == null) return null; // require a signature segment + + const dec = std.base64.url_safe_no_pad.Decoder; + const n = dec.calcSizeForSlice(payload_b64) catch return null; + const buf = allocator.alloc(u8, n) catch return null; + defer allocator.free(buf); + dec.decode(buf, payload_b64) catch return null; + return std.json.parseFromSlice(std.json.Value, allocator, buf, .{}) catch null; +} + +/// The `exp` (unix-seconds expiry) claim of a JWT access/id token, or null. +pub fn parseJwtExp(allocator: std.mem.Allocator, token: []const u8) ?i64 { + var parsed = decodeJwtPayload(allocator, token) orelse return null; + defer parsed.deinit(); + return http.jsonIntAtPath(parsed.value, "exp"); +} + +/// Extract the ChatGPT account id from an id_token. `claim_path` is the JWT +/// claim holding the auth object (e.g. `https://api.openai.com/auth`); the +/// account id is its `chatgpt_account_id` field. Returns an owned copy. +pub fn extractAccountId( + allocator: std.mem.Allocator, + id_token: []const u8, + claim_path: []const u8, +) ?[]u8 { + var parsed = decodeJwtPayload(allocator, id_token) orelse return null; + defer parsed.deinit(); + // `claim_path` is a single literal claim key (e.g. + // `https://api.openai.com/auth`) that itself contains dots, so it is + // looked up directly rather than walked as a dotted path. + const claim = switch (parsed.value) { + .object => |o| o.get(claim_path) orelse return null, + else => return null, + }; + const account = switch (claim) { + .object => |o| o.get("chatgpt_account_id") orelse return null, + else => return null, + }; + return switch (account) { + .string => |s| allocator.dupe(u8, s) catch null, + else => null, + }; +} + +/// True when an access token is missing or within `margin` seconds of expiry. +pub fn needsRefresh(ts: TokenSet, now_unix: i64, margin: i64) bool { + if (ts.access_token == null) return false; // nothing to refresh (login path) + const exp = ts.expires_at orelse return false; // no intrinsic expiry (e.g. ghu_) + return exp - now_unix <= margin; +} + +/// True when an exchange is configured but the stored exchange token is +/// missing or within `margin` seconds of expiry. +pub fn needsExchange(oauth: OAuthDeviceAuth, ts: TokenSet, now_unix: i64, margin: i64) bool { + if (oauth.exchange == null) return false; + const ex = ts.exchange orelse return true; + const exp = ex.expires_at orelse return false; // no expiry => assume durable + return exp - now_unix <= margin; +} + +/// Build the request-ready credential from a (refreshed/exchanged) token set. +/// The exchanged token wins over the access token; a codex account id becomes +/// a `chatgpt-account-id` header. All strings are duped into `arena`. +pub fn buildCredential( + arena: std.mem.Allocator, + oauth: OAuthDeviceAuth, + ts: TokenSet, +) !ResolvedCredential { + var base_url_override: ?[]const u8 = null; + const secret: []const u8 = blk: { + if (ts.exchange) |ex| { + if (ex.base_url) |bu| base_url_override = try arena.dupe(u8, bu); + break :blk ex.token; + } + break :blk ts.access_token orelse return AuthError.AuthUnresolved; + }; + + var headers: std.ArrayList(Header) = .empty; + if (oauth.account_id_jwt_claim != null) { + if (ts.account_id) |aid| { + try headers.append(arena, .{ + .name = "chatgpt-account-id", + .value = try arena.dupe(u8, aid), + }); + } + } + + return .{ + .api_key = try arena.dupe(u8, secret), + .base_url_override = base_url_override, + .extra_headers = try headers.toOwnedSlice(arena), + }; +} + +/// Assemble a persisted `TokenSet` from a fresh OAuth token response. +/// `expires_at` is derived from `expires_in` (preferred) or the access +/// token's JWT `exp`. A codex account id is extracted when configured. All +/// strings are duped into `arena`. +pub fn tokensToTokenSet( + arena: std.mem.Allocator, + oauth: OAuthDeviceAuth, + tokens: OAuthTokens, + now_unix: i64, +) !TokenSet { + const access = try arena.dupe(u8, tokens.access_token); + const expires_at: ?i64 = blk: { + if (tokens.expires_in) |e| break :blk now_unix + e; + break :blk parseJwtExp(arena, access); + }; + var account_id: ?[]const u8 = null; + if (oauth.account_id_jwt_claim) |claim| { + if (tokens.id_token) |idt| { + account_id = extractAccountId(arena, idt, claim); + } + } + return .{ + .type = "oauth_device", + .access_token = access, + .refresh_token = if (tokens.refresh_token) |r| try arena.dupe(u8, r) else null, + .id_token = if (tokens.id_token) |i| try arena.dupe(u8, i) else null, + .expires_at = expires_at, + .account_id = account_id, + }; +} + +const t = std.testing; + +test "token storage: save, load, delete round-trip" { + const io = t.io; + var tmp = t.tmpDir(.{}); + defer tmp.cleanup(); + var path_buf: [std.fs.max_path_bytes]u8 = undefined; + const n = try tmp.dir.realPath(io, &path_buf); + const auth_dir = try std.fmt.allocPrint(t.allocator, "{s}/auth", .{path_buf[0..n]}); + defer t.allocator.free(auth_dir); + + // Absent => null. + try t.expect((try loadTokenSet(t.allocator, io, auth_dir, "ghost")) == null); + + const ts: TokenSet = .{ + .type = "oauth_device", + .access_token = "ghu_abc", + .refresh_token = "rt_xyz", + .expires_at = 1700000000, + .exchange = .{ .token = "tkn", .expires_at = 1700001800, .base_url = "https://api.x" }, + }; + try saveTokenSet(t.allocator, io, auth_dir, "github_copilot", ts); + + var loaded = (try loadTokenSet(t.allocator, io, auth_dir, "github_copilot")).?; + defer loaded.deinit(); + try t.expectEqualStrings("ghu_abc", loaded.value.access_token.?); + try t.expectEqualStrings("rt_xyz", loaded.value.refresh_token.?); + try t.expectEqual(@as(?i64, 1700000000), loaded.value.expires_at); + try t.expect(loaded.value.id_token == null); + try t.expectEqualStrings("tkn", loaded.value.exchange.?.token); + try t.expectEqualStrings("https://api.x", loaded.value.exchange.?.base_url.?); + + try t.expect(try deleteTokenSet(t.allocator, io, auth_dir, "github_copilot")); + try t.expect(!try deleteTokenSet(t.allocator, io, auth_dir, "github_copilot")); + try t.expect((try loadTokenSet(t.allocator, io, auth_dir, "github_copilot")) == null); +} + +test "AuthConfig: api_key variant" { + const a: AuthConfig = .{ .api_key = .{ .key = "sk-resolved" } }; + try t.expectEqual(AuthType.api_key, @as(AuthType, a)); + try t.expectEqualStrings("sk-resolved", a.api_key.key.?); +} + +test "AuthConfig: oauth_device defaults" { + const a: AuthConfig = .{ .oauth_device = .{ + .client_id = "Iv1.x", + .device_code_url = "https://github.com/login/device/code", + .token_url = "https://github.com/login/oauth/access_token", + } }; + try t.expectEqual(DeviceDialect.token, a.oauth_device.dialect); + try t.expectEqual(TokenRequestFormat.form, a.oauth_device.token_request_format); + try t.expect(a.oauth_device.exchange == null); +} + +test "TokenSet: defaults" { + const ts: TokenSet = .{}; + try t.expectEqualStrings("oauth_device", ts.type); + try t.expect(ts.access_token == null); + try t.expect(ts.exchange == null); +} + +/// Build a `header.payload.sig` JWT whose payload is `payload_json`, +/// base64url-no-pad encoded. Allocated in `arena`. +fn makeJwt(arena: std.mem.Allocator, payload_json: []const u8) ![]u8 { + const enc = std.base64.url_safe_no_pad.Encoder; + const header = "{\"alg\":\"none\"}"; + var hbuf: [64]u8 = undefined; + const h = enc.encode(&hbuf, header); + const pbuf = try arena.alloc(u8, enc.calcSize(payload_json.len)); + const p = enc.encode(pbuf, payload_json); + return std.fmt.allocPrint(arena, "{s}.{s}.sig", .{ h, p }); +} + +test "parseJwtExp + extractAccountId" { + var aa = std.heap.ArenaAllocator.init(t.allocator); + defer aa.deinit(); + const a = aa.allocator(); + const jwt = try makeJwt(a, + \\{"exp":1700000000,"https://api.openai.com/auth":{"chatgpt_account_id":"acct_123"}} + ); + try t.expectEqual(@as(?i64, 1700000000), parseJwtExp(a, jwt)); + const aid = extractAccountId(a, jwt, "https://api.openai.com/auth").?; + try t.expectEqualStrings("acct_123", aid); + // Wrong claim path => null. + try t.expect(extractAccountId(a, jwt, "nope") == null); + // Malformed token => null. + try t.expect(parseJwtExp(a, "not-a-jwt") == null); +} + +test "parseOAuthTokens: required access_token, optional rest" { + var parsed = try std.json.parseFromSlice(std.json.Value, t.allocator, + \\{"access_token":"at","refresh_token":"rt","id_token":"it","expires_in":1800} + , .{}); + defer parsed.deinit(); + const toks = parseOAuthTokens(parsed.value).?; + try t.expectEqualStrings("at", toks.access_token); + try t.expectEqualStrings("rt", toks.refresh_token.?); + try t.expectEqual(@as(?i64, 1800), toks.expires_in); + + var p2 = try std.json.parseFromSlice(std.json.Value, t.allocator, "{\"error\":\"x\"}", .{}); + defer p2.deinit(); + try t.expect(parseOAuthTokens(p2.value) == null); +} + +test "formEncode: percent-encodes reserved characters" { + var aa = std.heap.ArenaAllocator.init(t.allocator); + defer aa.deinit(); + const body = try formEncode(aa.allocator(), &.{ + .{ "grant_type", "urn:ietf:params:oauth:grant-type:device_code" }, + .{ "client_id", "Iv1.abc" }, + }); + try t.expectEqualStrings( + "grant_type=urn%3Aietf%3Aparams%3Aoauth%3Agrant-type%3Adevice_code&client_id=Iv1.abc", + body, + ); +} + +test "needsRefresh / needsExchange predicates" { + const now: i64 = 1000; + // Durable token (no expiry) never needs refresh. + try t.expect(!needsRefresh(.{ .access_token = "x" }, now, 120)); + // Within margin => refresh. + try t.expect(needsRefresh(.{ .access_token = "x", .expires_at = 1100 }, now, 120)); + // Comfortably fresh => no. + try t.expect(!needsRefresh(.{ .access_token = "x", .expires_at = 5000 }, now, 120)); + + const oauth: OAuthDeviceAuth = .{ + .client_id = "c", + .device_code_url = "u", + .token_url = "u", + .exchange = .{ .url = "https://x" }, + }; + // Exchange configured but none stored => needs exchange. + try t.expect(needsExchange(oauth, .{ .access_token = "x" }, now, 120)); + // Stored exchange near expiry => needs exchange. + try t.expect(needsExchange(oauth, .{ .exchange = .{ .token = "t", .expires_at = 1050 } }, now, 120)); + // Fresh exchange => no. + try t.expect(!needsExchange(oauth, .{ .exchange = .{ .token = "t", .expires_at = 9000 } }, now, 120)); + // No exchange configured => never. + const no_ex: OAuthDeviceAuth = .{ .client_id = "c", .device_code_url = "u", .token_url = "u" }; + try t.expect(!needsExchange(no_ex, .{ .access_token = "x" }, now, 120)); +} + +test "buildCredential: copilot exchange token + dynamic base_url" { + var aa = std.heap.ArenaAllocator.init(t.allocator); + defer aa.deinit(); + const oauth: OAuthDeviceAuth = .{ + .client_id = "c", + .device_code_url = "u", + .token_url = "u", + .exchange = .{ .url = "https://x" }, + }; + const ts: TokenSet = .{ + .access_token = "ghu_durable", + .exchange = .{ .token = "tid", .base_url = "https://api.individual.githubcopilot.com" }, + }; + const cred = try buildCredential(aa.allocator(), oauth, ts); + try t.expectEqualStrings("tid", cred.api_key); + try t.expectEqualStrings("https://api.individual.githubcopilot.com", cred.base_url_override.?); + try t.expectEqual(@as(usize, 0), cred.extra_headers.len); +} + +test "buildCredential: codex access token + account-id header" { + var aa = std.heap.ArenaAllocator.init(t.allocator); + defer aa.deinit(); + const oauth: OAuthDeviceAuth = .{ + .dialect = .codex, + .client_id = "c", + .device_code_url = "u", + .token_url = "u", + .device_poll_url = "p", + .account_id_jwt_claim = "https://api.openai.com/auth", + }; + const ts: TokenSet = .{ .access_token = "jwt-access", .account_id = "acct_9" }; + const cred = try buildCredential(aa.allocator(), oauth, ts); + try t.expectEqualStrings("jwt-access", cred.api_key); + try t.expect(cred.base_url_override == null); + try t.expectEqual(@as(usize, 1), cred.extra_headers.len); + try t.expectEqualStrings("chatgpt-account-id", cred.extra_headers[0].name); + try t.expectEqualStrings("acct_9", cred.extra_headers[0].value); +} + +test "tokensToTokenSet: derives expires_at from expires_in and extracts account_id" { + var aa = std.heap.ArenaAllocator.init(t.allocator); + defer aa.deinit(); + const a = aa.allocator(); + const idt = try makeJwt(a, + \\{"https://api.openai.com/auth":{"chatgpt_account_id":"acct_77"}} + ); + const oauth: OAuthDeviceAuth = .{ + .dialect = .codex, + .client_id = "c", + .device_code_url = "u", + .token_url = "u", + .device_poll_url = "p", + .account_id_jwt_claim = "https://api.openai.com/auth", + }; + const ts = try tokensToTokenSet(a, oauth, .{ + .access_token = "at", + .refresh_token = "rt", + .id_token = idt, + .expires_in = 1800, + }, 1000); + try t.expectEqual(@as(?i64, 2800), ts.expires_at); + try t.expectEqualStrings("rt", ts.refresh_token.?); + try t.expectEqualStrings("acct_77", ts.account_id.?); +} |