oauth2.bend
bend-kit-oauth2@0.3.0.1 · 339 lines · 0 definitions
1# OAuth 2.0 client credentials, refresh, and authorization code with PKCE over Hairpin. Source: https://github.com/paymog/bend-kit/tree/main/oauth2
2import Base
3import bend-kit-crypto@0.2.2.1/crypto.bend as Crypto
4import bend-kit-hairpin@0.3.0.0/hairpin.bend as Hairpin
5import bend-kit-http@0.32.0.0/http.bend as Http
6import bend-kit-time@0.1.2.1/time.bend as Time
7# By hash, as hairpin imports them: bend-kit-url@0.4.1.0, -json@0.5.0.1, -encoding@0.3.0.0, -bytes@0.3.0.0.
8import bend-kit-url@0.4.1.0/url.bend as Url
9import bend-kit-json@0.5.0.1/json.bend as Json
10import bend-kit-encoding@0.3.0.0/encoding.bend as Enc
11import bend-kit-bytes@0.3.0.0/bytes.bend as Bytes
12
13# RFC 6749 and RFC 7636. Text is a String of code points; form values go out as UTF-8.
14# token: the token endpoint URL. secret: "" for a public client, which sends client_id in the body;
15# a confidential client authenticates with HTTP Basic (RFC 6749 §2.3.1).
16type Config is Data:
17 Config{token: String, id: String, secret: String}
18
19# kind: token_type, as "Bearer". refresh: "" for none. scope: "" when the server did not say.
20# expires: when the access token lapses, counted from just before the request; None without expires_in.
21type Token is Data:
22 Token{access: String, kind: String, refresh: String, scope: String, expires: Maybe<&2, Time.Instant>}
23
24# ErrNet: the request did not complete. ErrOAuth: an RFC 6749 §5.2 error with its status, or a §4.1.2.1
25# error in a callback, status 0. ErrReply: not a Bearer token response, with its status and text. ErrState: the
26# callback's state is not ours (§10.12). ErrCrypto: the random source or SHA-256 failed. ErrExpired: the
27# token lapsed and has no refresh token.
28type Err is Data:
29 ErrNet{e: Hairpin.Err}
30 ErrOAuth{status: U32, code: String, why: String}
31 ErrReply{status: U32, body: String}
32 ErrState{}
33 ErrCrypto{code: U32, why: String}
34 ErrExpired{}
35
36# ---- base64url
37
38def b64url.ch(+c: U32, t: String) -> String:
39 match c:
40 case 43:
41 SCon{Chr{45}, t}
42 case 47:
43 SCon{Chr{95}, t}
44 case 61:
45 t
46 case _:
47 SCon{Chr{c}, t}
48
49def b64url.go(s: String) -> String:
50 match s:
51 case SNil{}:
52 SNil{}
53 case SCon{Chr{+c}, t}:
54 b64url.ch(c, b64url.go(t))
55
56# Base64url without padding (RFC 4648 §5, RFC 7636 Appendix A).
57def b64url(b: Bytes.Bytes) -> String:
58 b64url.go(Bytes.to_base64(b))
59
60# ---- forms
61
62def utf8(+s: String) -> String:
63 Bytes.to_string(Enc.utf8.encode(s))
64
65def field(m: Map<&2, String>, k: String, +v: String) -> Map<&2, String>:
66 Map.set(&2, String, m, k, utf8(v))
67
68def scoped(+scope: String, +m: Map<&2, String>) -> Map<&2, String>:
69 Bool.pick(Map<&2, String>, String.is_empty(scope), m, field(m, "scope", scope))
70
71def form(+k: String, +v: String) -> Map<&2, String>:
72 field(Map.new(&2, String), k, v)
73
74# RFC 6749 §2.3.1: id and secret are form-encoded before base64.
75def basic(+id: String, +secret: String) -> String:
76 "Basic " ++ Bytes.to_base64(Bytes.from_string(Url.pct.encode_q(utf8(id)) ++ ":" ++ Url.pct.encode_q(utf8(secret))))
77
78def auth.headers(+id: String, +secret: String) -> Map<&2, List<&2, String>>:
79 +h = Http.set(Http.set(Http.empty(), "content-type", "application/x-www-form-urlencoded"), "accept", "application/json")
80 Bool.pick(Map<&2, List<&2, String>>, String.is_empty(secret), h, Http.set(h, "authorization", basic(id, secret)))
81
82def auth.body(+id: String, +secret: String, +m: Map<&2, String>) -> Map<&2, String>:
83 Bool.pick(Map<&2, String>, String.is_empty(secret), field(m, "client_id", id), m)
84
85# The form body of a token request from cfg's client.
86def body(+id: String, +secret: String, m: Map<&2, String>) -> String:
87 Url.form(auth.body(id, secret, m))
88
89# ---- token responses (RFC 6749 §5)
90
91type Got is Data:
92 Got{access: String, kind: String, refresh: String, scope: String, expires: String, error: String, desc: String}
93
94def got.put(g: Got, +k: String, +v: String) -> Got:
95 Got{a, t, r, s, e, er, d} = g
96 Got{Bool.pick(String, String.eq(k, "access_token"), v, a), Bool.pick(String, String.eq(k, "token_type"), v, t),
97 Bool.pick(String, String.eq(k, "refresh_token"), v, r), Bool.pick(String, String.eq(k, "scope"), v, s),
98 Bool.pick(String, String.eq(k, "expires_in"), v, e), Bool.pick(String, String.eq(k, "error"), v, er),
99 Bool.pick(String, String.eq(k, "error_description"), v, d)}
100
101# A string's text, or a number's, as some servers send expires_in as "3600".
102def got.text(v: Json.Val) -> String:
103 match v:
104 case Json.Str{s}:
105 Enc.utf8.decode(s)
106 case Json.Num{s}:
107 Bytes.to_string(s)
108 case other:
109 ""
110
111def got.go(kvs: List<&1, Bytes.Bytes & Json.Val>, g: Got) -> Got:
112 match kvs:
113 case Nil{}:
114 g
115 case Con{(k, v), t}:
116 got.go(t, got.put(g, Bytes.to_string(k), got.text(v)))
117
118def got.obj(v: Json.Val) -> Maybe<&2, Got>:
119 match v:
120 case Json.Obj{kvs}:
121 Some{got.go(kvs, Got{"", "", "", "", "", "", ""})}
122 case other:
123 None{}
124
125def got(m: Maybe<&1, Json.Val>) -> Maybe<&2, Got>:
126 match m:
127 case None{}:
128 None{}
129 case Some{v}:
130 got.obj(v)
131
132def expiry(now: Time.Instant, m: Maybe<&2, U32>) -> Maybe<&2, Time.Instant>:
133 match m:
134 case None{}:
135 None{}
136 case Some{n}:
137 Some{Time.Instant.add(now, Time.Duration.of_secs(Time.i64(n)))}
138
139# A 2xx with an access token of type Bearer (RFC 6750 §4, case-insensitive), the only kind request sends.
140def good(+status: U32, g: Got) -> Bool:
141 Got{a, t, r, s, e, er, d} = g
142 Bool.and(Bool.and(U32.is_le(200, status), U32.is_lt(status, 300)), Bool.and(Bool.not(String.is_empty(a)), String.eq(String.to_lower(t), "bearer")))
143
144# §6: a refresh reply without refresh_token keeps the old one. b: the body, decoded only for an error.
145def token.pick(ok: Bool, +status: U32, +old: String, now: Time.Instant, b: Bytes.Bytes, g: Got) -> Result<&1, &1, Err, Token>:
146 match ok:
147 case True{}:
148 Got{a, t, +r, s, e, er, d} = g
149 Done{Token{a, t, Bool.pick(String, String.is_empty(r), old, r), s, expiry(now, Json.u32.num(e))}}
150 case False{}:
151 Got{a, t, r, s, e, +er, d} = g
152 Fail{Bool.pick(Err, String.is_empty(er), ErrReply{status, Enc.utf8.decode(b)}, ErrOAuth{status, er, d})}
153
154def token.of(+status: U32, +old: String, now: Time.Instant, b: Bytes.Bytes, m: Maybe<&2, Got>) -> Result<&1, &1, Err, Token>:
155 match m:
156 case None{}:
157 Fail{ErrReply{status, Enc.utf8.decode(b)}}
158 case Some{+g}:
159 token.pick(good(status, g), status, old, now, b, g)
160
161def parse.copy(+status: U32, +old: String, now: Time.Instant, r: Bytes.Bytes & Bytes.Bytes) -> Result<&1, &1, Err, Token>:
162 (b, c) = r
163 token.of(status, old, now, b, got(Json.parse.bytes(c)))
164
165# A token endpoint's reply at status, requested at now. old: the refresh token to keep when none comes back.
166def parse(+status: U32, +old: String, now: Time.Instant, b: Bytes.Bytes) -> Result<&1, &1, Err, Token>:
167 parse.copy(status, old, now, Bytes.slice(b, 0, 4294967295))
168
169def reply(+old: String, now: Time.Instant, r: Result<&1, &1, Hairpin.Err, Http.Res>) -> Result<&1, &1, Err, Token>:
170 match r:
171 case Fail{e}:
172 Fail{ErrNet{e}}
173 case Done{res}:
174 Http.Res{+status, h, b} = res
175 parse(status, old, now, b)
176
177def grant.done(+old: String, now: Time.Instant, x: Hairpin.Client & Result<&1, &1, Hairpin.Err, Http.Res>) ->
178 Hairpin.Client & Result<&1, &1, Err, Token>:
179 (h, r) = x
180 (h, reply(old, now, r))
181
182# POST m to the token endpoint. Hairpin sends a POST once.
183def grant(h: Hairpin.Client, cfg: Config, m: Map<&2, String>, +old: String) -> IO(Hairpin.Client & Result<&1, &1, Err, Token>):
184 Config{url, +id, +secret} = cfg
185 do IO<Hairpin.Client & Result<&1, &1, Err, Token>>:
186 now : Time.Instant <- Time.now()
187 x : Hairpin.Client & Result<&1, &1, Hairpin.Err, Http.Res> <-
188 Hairpin.request(h, "POST", url, auth.headers(id, secret), Http.from_string(body(id, secret, m)))
189 return grant.done(old, now, x)
190
191# ---- grants
192
193# RFC 6749 §4.4. scope: "" for the server's default.
194def client_credentials(h: Hairpin.Client, cfg: Config, +scope: String) -> IO(Hairpin.Client & Result<&1, &1, Err, Token>):
195 grant(h, cfg, scoped(scope, form("grant_type", "client_credentials")), "")
196
197# RFC 6749 §4.1.3 with RFC 7636 §4.5: the code from callback, the same redirect_uri, and the verifier.
198def code(h: Hairpin.Client, cfg: Config, +code: String, +redirect: String, +verifier: String) ->
199 IO(Hairpin.Client & Result<&1, &1, Err, Token>):
200 grant(h, cfg, field(field(field(form("grant_type", "authorization_code"), "code", code), "redirect_uri", redirect), "code_verifier", verifier), "")
201
202def refresh.go(none: Bool, h: Hairpin.Client, cfg: Config, +r: String, +scope: String) -> IO(Hairpin.Client & Result<&1, &1, Err, Token>):
203 match none:
204 case True{}:
205 IO.pure(Hairpin.Client & Result<&1, &1, Err, Token>, (h, Fail{ErrExpired{}}))
206 case False{}:
207 grant(h, cfg, scoped(scope, field(form("grant_type", "refresh_token"), "refresh_token", r)), r)
208
209# RFC 6749 §6. scope: "" keeps the granted scope. ErrExpired when tok has no refresh token.
210def refresh(h: Hairpin.Client, cfg: Config, tok: Token, +scope: String) -> IO(Hairpin.Client & Result<&1, &1, Err, Token>):
211 Token{a, k, +r, s, e} = tok
212 refresh.go(String.is_empty(r), h, cfg, r, scope)
213
214def expiring.at(e: Maybe<&2, Time.Instant>, now: Time.Instant, +skew: U32) -> Bool:
215 match e:
216 case None{}:
217 False{}
218 case Some{at}:
219 Bool.not(Cmp.is_lt(Time.Instant.cmp(Time.Instant.add(now, Time.Duration.of_secs(Time.i64(skew))), at)))
220
221# Does tok lapse within skew seconds of now? A token without expires_in never does.
222def expiring(tok: Token, now: Time.Instant, +skew: U32) -> Bool:
223 Token{a, k, r, s, e} = tok
224 expiring.at(e, now, skew)
225
226def fresh.go(due: Bool, h: Hairpin.Client, cfg: Config, +tok: Token) -> IO(Hairpin.Client & Result<&1, &1, Err, Token>):
227 match due:
228 case True{}:
229 refresh(h, cfg, tok, "")
230 case False{}:
231 IO.pure(Hairpin.Client & Result<&1, &1, Err, Token>, (h, Done{tok}))
232
233# tok, or a refreshed one when it lapses within skew seconds.
234def fresh(h: Hairpin.Client, cfg: Config, +tok: Token, +skew: U32) -> IO(Hairpin.Client & Result<&1, &1, Err, Token>):
235 do IO<Hairpin.Client & Result<&1, &1, Err, Token>>:
236 now : Time.Instant <- Time.now()
237 fresh.go(expiring(tok, now, skew), h, cfg, tok)
238
239def fresh.cc.go(due: Bool, h: Hairpin.Client, cfg: Config, +scope: String, +tok: Token) -> IO(Hairpin.Client & Result<&1, &1, Err, Token>):
240 match due:
241 case True{}:
242 client_credentials(h, cfg, scope)
243 case False{}:
244 IO.pure(Hairpin.Client & Result<&1, &1, Err, Token>, (h, Done{tok}))
245
246# tok, or a new client-credentials token when it lapses within skew seconds (§4.4.3: no refresh token).
247def fresh.cc(h: Hairpin.Client, cfg: Config, +scope: String, +tok: Token, +skew: U32) -> IO(Hairpin.Client & Result<&1, &1, Err, Token>):
248 do IO<Hairpin.Client & Result<&1, &1, Err, Token>>:
249 now : Time.Instant <- Time.now()
250 fresh.cc.go(expiring(tok, now, skew), h, cfg, scope, tok)
251
252# ---- authorization code with PKCE (RFC 7636)
253
254def random.of(r: Result<&1, &1, U32 & String, U32 & Array<U32>>) -> Result<&1, &1, Err, String>:
255 match r:
256 case Fail{(c, why)}:
257 Fail{ErrCrypto{c, why}}
258 case Done{(len, buf)}:
259 Done{b64url(Bytes.Bytes{len, buf})}
260
261# n octets from the OS secure random source, as base64url.
262def random(+n: U32) -> IO(Result<&1, &1, Err, String>):
263 do IO<Result<&1, &1, Err, String>>:
264 r : Result<&1, &1, U32 & String, U32 & Array<U32>> <- Crypto.random.words(n)
265 return random.of(r)
266
267# §4.1: 32 random octets, 43 unreserved chars.
268def verifier() -> IO(Result<&1, &1, Err, String>):
269 random(32)
270
271# An unguessable state for the authorization request (RFC 6749 §10.12).
272def state() -> IO(Result<&1, &1, Err, String>):
273 random(16)
274
275def challenge.words(b: Bytes.Bytes) -> IO(Result<&1, &1, Err, String>):
276 Bytes.Bytes{+len, buf} = b
277 do IO<Result<&1, &1, Err, String>>:
278 r : Result<&1, &1, U32 & String, U32 & Array<U32>> <- Crypto.sha256.words(len, buf)
279 return random.of(r)
280
281# §4.2 S256: BASE64URL(SHA256(ASCII(verifier))).
282def challenge(+verifier: String) -> IO(Result<&1, &1, Err, String>):
283 challenge.words(Bytes.from_string(verifier))
284
285def qmark(s: String) -> Bool:
286 match s:
287 case SNil{}:
288 False{}
289 case SCon{Chr{+c}, t}:
290 Bool.or(U32.is_eq(c, 63), qmark(t))
291
292# RFC 6749 §4.1.1 with RFC 7636 §4.3: the URL to send the user to. endpoint may carry its own query.
293def authorize.url(cfg: Config, +endpoint: String, +redirect: String, +scope: String, +state: String, +challenge: String) -> String:
294 Config{t, +id, s} = cfg
295 +q = field(field(field(field(field(form("response_type", "code"), "client_id", id), "redirect_uri", redirect), "state", state),
296 "code_challenge", challenge), "code_challenge_method", "S256")
297 endpoint ++ Bool.pick(String, qmark(endpoint), "&", "?") ++ Url.form(scoped(scope, q))
298
299def param.of(r: Map<&2, String> & String) -> String:
300 (n, v) = r
301 v
302
303def param(+m: Map<&2, String>, k: String) -> String:
304 param.of(Map.get(String, "", m, k))
305
306def callback.pick(+err: String, desc: String, +got: String, +code: String, +state: String) -> Result<&1, &1, Err, String>:
307 Bool.pick(Result<&1, &1, Err, String>, Bool.not(String.eq(got, state)), Fail{ErrState{}},
308 Bool.pick(Result<&1, &1, Err, String>, Bool.not(String.is_empty(err)), Fail{ErrOAuth{0, err, desc}},
309 Bool.pick(Result<&1, &1, Err, String>, String.is_empty(code), Fail{ErrReply{0, "no code"}}, Done{code})))
310
311def callback.m(+state: String, m: Maybe<&2, Url.Url>) -> Result<&1, &1, Err, String>:
312 match m:
313 case None{}:
314 Fail{ErrReply{0, "bad callback query"}}
315 case Some{Url.Url{p, +q}}:
316 callback.pick(param(q, "error"), param(q, "error_description"), param(q, "state"), param(q, "code"), state)
317
318def callback.frag(+state: String, r: String & String) -> Result<&1, &1, Err, String>:
319 (q, f) = r
320 callback.m(state, Url.parse("/?" ++ q))
321
322def callback.q(+state: String, r: String & String) -> Result<&1, &1, Err, String>:
323 (p, rest) = r
324 callback.frag(state, Url.take_to(rest, 35))
325
326# §4.1.2: the code in the redirect to redirect_uri, once its state matches ours; the server's error if it sent one.
327def callback(url: String, +state: String) -> Result<&1, &1, Err, String>:
328 callback.q(state, Url.take_to(url, 63))
329
330# ---- bearer requests (RFC 6750 §2.1)
331
332def bearer(tok: Token, h: Map<&2, List<&2, String>>) -> Map<&2, List<&2, String>>:
333 Token{a, k, r, s, e} = tok
334 Http.set(h, "authorization", "Bearer " ++ a)
335
336# Hairpin.request with Authorization: Bearer <access>, over any authorization header in headers.
337def request(c: Hairpin.Client, tok: Token, +method: String, url: String, headers: Map<&2, List<&2, String>>, body: Bytes.Bytes) ->
338 IO(Hairpin.Client & Result<&1, &1, Hairpin.Err, Http.Res>):
339 Hairpin.request(c, method, url, bearer(tok, headers), body)