Circular references between two (or more) chemas cause a dead loop

[KonstantinSviridov]

Hi!

While circular references within a single schema are supported, the situation is different for circular references between several schemas. The code is

var ZSchema = require("z-schema");

var ref1 = "http://www.example.org/schema1/#";
var ref2 = "http://www.example.org/schema2/#";

var schema1 = {
    "$schema": "http://json-schema.org/draft-04/schema#",
    "id": ref1, 
    "properties": {
        "prop1": {
           "$ref":  ref2
        }
    }
};

var schema2 = {
    "$schema": "http://json-schema.org/draft-04/schema#",
    "id": ref2,
    "properties": {
        "prop1": {
           "$ref":  ref1
        }
    }
};

var validator = new ZSchema();
validator.setRemoteReference(ref1, schema1);
validator.setRemoteReference(ref2, schema2);

var valid = validator.validateSchema(schema1);
console.log("valid: " + JSON.stringify(valid))
console.log("errors: " + JSON.stringify(validator.getLastErrors(),null,2))

And the output is

C:\work\circular-refs\node_modules\z-schema\src\Utils.js:4
    return /^https?:\/\//.test(uri);
                          ^

RangeError: Maximum call stack size exceeded
    at RegExp.test (native)
    at Object.exports.isAbsoluteUri (C:\work\circular-refs\node_modules\z-schema\src\Utils.js:4:27)
    at mergeReference (C:\work\circular-refs\node_modules\z-schema\src\SchemaCompilation.js:8:15)
    at collectReferences (C:\work\circular-refs\node_modules\z-schema\src\SchemaCompilation.js:52:18)
    at collectReferences (C:\work\circular-refs\node_modules\z-schema\src\SchemaCompilation.js:82:13)
    at ZSchema.collectReferences (C:\work\circular-refs\node_modules\z-schema\src\SchemaCompilation.js:82:13)
    at ZSchema.exports.compileSchema (C:\work\circular-refs\node_modules\z-schema\src\SchemaCompilation.js:219:34)
    at ZSchema.exports.getSchemaByUri (C:\work\circular-refs\node_modules\z-schema\src\SchemaCache.js:123:49)
    at ZSchema.exports.compileSchema (C:\work\circular-refs\node_modules\z-schema\src\SchemaCompilation.js:224:51)
    at ZSchema.exports.getSchemaByUri (C:\work\circular-refs\node_modules\z-schema\src\SchemaCache.js:123:49)

Trying to pass both schemas in array

var ZSchema = require("z-schema");

var ref1 = "http://www.example.org/schema1/#";
var ref2 = "http://www.example.org/schema2/#";

var schema1 = {
    "$schema": "http://json-schema.org/draft-04/schema#",
    "id": ref1, 
    "properties": {
        "prop1": {
           "$ref":  ref2
        }
    }
};

var schema2 = {
    "$schema": "http://json-schema.org/draft-04/schema#",
    "id": ref2,
    "properties": {
        "prop1": {
           "$ref":  ref1
        }
    }
};

var validator = new ZSchema();
//validator.setRemoteReference(ref1, schema1);
//validator.setRemoteReference(ref2, schema2);

var valid = validator.validateSchema([schema1,schema2]);
console.log("valid: " + JSON.stringify(valid))
console.log("errors: " + JSON.stringify(validator.getLastErrors(),null,2))

produces invalid errors:

valid: false
errors: [
  {
    "code": "UNRESOLVABLE_REFERENCE",
    "params": [
      "http://www.example.org/schema1/#"
    ],
    "message": "Reference could not be resolved: http://www.example.org/schema1/#",
    "path": "#/properties/prop1",
    "schemaId": "http://www.example.org/schema2/#"
  },
  {
    "code": "UNRESOLVABLE_REFERENCE",
    "params": [
      "http://www.example.org/schema2/#"
    ],
    "message": "Reference could not be resolved: http://www.example.org/schema2/#",
    "path": "#/properties/prop1",
    "schemaId": "http://www.example.org/schema1/#"
  }
]

In the last case validation passes fine after the cycle is broken in one place, so, the references values themselves are not the reason.

Regards,
Konstantin