Make API auth contexts safe to copy across threads

test/config.nims

@@ -1,2 +1,3 @@
 switch("path", "../src")
 switch("verbosity", "0")
+switch("threads", "on")

test/tauth.nim

@@ -0,0 +1,131 @@
+import std/[json, options, unittest]
+import jwt_full
+import buffoonery/auth
+
+const testIssuer = "https://issuer.example"
+
+proc keyNode(kid = "original"): JsonNode =
+  %*{"kty": "oct", "alg": "HS256", "kid": kid,
+     "k": "c2VjcmV0", "metadata": {"labels": ["original"]}}
+
+proc newContext(): ApiAuthContext =
+  initApiAuthContext("example.com", "test", @[testIssuer], testIssuer,
+    @[testIssuer], "original", @[initJwk(keyNode())])
+
+proc tokenFor(kid = "original", issuer = testIssuer): JWT =
+  # Lookup only needs the header and issuer; signing is tested separately.
+  createSignedJwt(initJoseHeader(%*{"alg": "HS256", "kid": kid}),
+    initJwtClaims(%*{"iss": issuer}), initJwk(keyNode(kid)))
+
+when compileOption("threads"):
+  type WorkerInput = tuple[ctx: ApiAuthContext, ok: ptr bool]
+
+  proc useContext(input: WorkerInput) {.thread.} =
+    var ctx = input.ctx
+    try:
+      ctx.validAudiences[0] = "worker"
+      let key = ctx.findSigningKey(tokenFor(), false)
+      key["metadata"].get["labels"][0].str = "worker"
+      ctx.addSigningKeys(testIssuer, @[initJwk(keyNode("worker"))])
+      input.ok[] = ctx.findSigningKey(tokenFor("worker"), false).kid.get == "worker"
+    except CatchableError:
+      input.ok[] = false
+
+suite "auth context value semantics":
+  test "copies own their configuration and signing-key cache":
+    var original = newContext()
+    var copied = original
+    copied.appDomain[0] = 'E'
+    copied.validAudiences[0][0] = 'H'
+    copied.trustedIssuers.add "https://other.example"
+    copied.addSigningKeys(testIssuer, @[initJwk(keyNode("replacement"))])
+
+    check original.appDomain == "example.com"
+    check original.validAudiences == @[testIssuer]
+    check original.trustedIssuers == @[testIssuer]
+    check original.findSigningKey(tokenFor(), false).kid.get == "original"
+    check copied.findSigningKey(tokenFor("replacement"), false).kid.get == "replacement"
+    expect AuthError:
+      discard copied.findSigningKey(tokenFor(), false)
+    expect AuthError:
+      discard original.findSigningKey(tokenFor("replacement"), false)
+
+  test "constructor and added keys do not retain caller-owned JSON":
+    let node = keyNode()
+    var ctx = initApiAuthContext("example.com", "test", @[testIssuer],
+      testIssuer, @[testIssuer], "original", @[initJwk(node)])
+    node["metadata"]["labels"][0].str = "changed"
+    check ctx.findSigningKey(tokenFor(), false)["metadata"].get["labels"][0].getStr == "original"
+
+    let added = keyNode("added")
+    ctx.addSigningKeys(testIssuer, @[initJwk(added)])
+    added["metadata"]["labels"][0].str = "changed"
+    check ctx.findSigningKey(tokenFor("added"), false)["metadata"].get["labels"][0].getStr == "original"
+
+  test "returned key metadata is independent of both context copies":
+    var original = newContext()
+    var copied = original
+    let key = copied.findSigningKey(tokenFor(), false)
+    key["metadata"].get["labels"][0].str = "changed"
+    check original.findSigningKey(tokenFor(), false)["metadata"].get["labels"][0].getStr == "original"
+    check copied.findSigningKey(tokenFor(), false)["metadata"].get["labels"][0].getStr == "original"
+
+  test "default contexts accept keys and reject missing keys without fetching":
+    var ctx: ApiAuthContext
+    expect AuthError:
+      discard ctx.findSigningKey(tokenFor(), false)
+    ctx.addSigningKeys(testIssuer, @[initJwk(keyNode())])
+    check ctx.findSigningKey(tokenFor(), false).kid.get == "original"
+
+  test "invalid key updates leave the existing cache intact":
+    var ctx = newContext()
+    let invalid = keyNode("invalid")
+    invalid.delete("alg")
+    expect AuthError:
+      ctx.addSigningKeys(testIssuer, @[initJwk(invalid)])
+    check ctx.findSigningKey(tokenFor(), false).kid.get == "original"
+
+  test "immutable contexts can sign tokens that mutable copies validate":
+    let original = newContext()
+    let token = original.newApiAccessToken("user")
+    var copied = original
+    copied.validateJWT(token)
+    check token.claims.sub.get == "user"
+
+  test "cached keys preserve RSA and EC variants":
+    var ctx: ApiAuthContext
+    let nodes = @[
+      %*{"kty": "RSA", "alg": "RS256", "kid": "rsa-public",
+         "n": "AQAB", "e": "AQAB"},
+      %*{"kty": "RSA", "alg": "RS256", "kid": "rsa-private",
+         "n": "AQAB", "e": "AQAB", "d": "Ag", "p": "Aw", "q": "BQ",
+         "oth": [{"r": "Bw", "d": "Ag", "t": "Aw"}]},
+      %*{"kty": "EC", "alg": "ES256", "kid": "ec-public",
+         "crv": "P-256", "x": "AQ", "y": "Ag"},
+      %*{"kty": "EC", "alg": "ES256", "kid": "ec-private",
+         "crv": "P-256", "x": "AQ", "y": "Ag", "d": "Aw"}]
+    for node in nodes:
+      let key = initJwk(node)
+      ctx.addSigningKeys(testIssuer, @[key])
+      let restored = ctx.findSigningKey(tokenFor(key.kid.get), false)
+      check restored.keyKind == key.keyKind
+      for name, value in node.pairs:
+        check restored[name].get == value
+      case key.keyKind
+      of RsaPublic: check restored.rsaPub == key.rsaPub
+      of RsaPrivate: check restored.rsaPrv == key.rsaPrv
+      of EcPublic: check restored.ecPub == key.ecPub
+      of EcPrivate: check restored.ecPrv == key.ecPrv
+      of Octet: discard
+
+  when compileOption("threads"):
+    test "workers mutate independent context copies":
+      var original = newContext()
+      var workers: array[2, Thread[WorkerInput]]
+      var succeeded: array[2, bool]
+      for i in 0 ..< workers.len:
+        createThread(workers[i], useContext, (original, addr succeeded[i]))
+      joinThreads(workers)
+      check succeeded == [true, true]
+      check original.validAudiences == @[testIssuer]
+      check original.findSigningKey(tokenFor(), false)["metadata"].get["labels"][0].getStr == "original"