Request validation plugin

[sshniro]

Resolves #1643
The plugin uses the json-schema validator to validate requests before sending them to upstream.
This plugin can be used to validate the header and body data.

[sshniro]

@membphis , @moonming should I write more test cases for different types of schema validations or rely on the JSON schema validator itself?

[membphis]

Add test case: Use illegal JSON request.

[membphis]

we need more test cases about the header schema

[membphis]

export the API create_validator : https://github.com/apache/incubator-apisix/blob/master/apisix/core/schema.lua#L26

then we can use it to confirm if the input conf is a valid JSON Schema.

[sshniro]

I do not understand this comment @membphis , ain't coreschema.check internally calls create_validator for validation?

[membphis]

here is the an valid example you provide, the user maybe provide a invalid schema:

"body_schema": {
    "type": "object",
    "required": ["required_payload"],
    "properties": {
            "emum_payload": {
            "type": "string",  # the user maybe specified a wrong type, eg: `str`
            "enum": ["enum_string_1", "enum_string_2"],
            "default": "enum_string_1"
        }
    }
}

here is detail:

[membphis]

another style, I think this one is better:

if not conf.body_schema then
    return
end

ngx.req.read_body()
local body = ngx.req.get_body_data()
local req_body, err

if headers["content-type"] == "application/x-www-form-urlencoded" then
    req_body, err = ngx.decode_args(body)
else -- JSON as default
    req_body, err = core.json.decode(body)
end

if not req_body then
    ... ...
    return 
end

local ok, err = core.schema.check(conf.body_schema, req_body)
...

[membphis]

@sshniro you can rebase your branch with master, the CI will faster.

[membphis]

here is the an valid example you provide, the user maybe provide a invalid schema:

"body_schema": {
    "type": "object",
    "required": ["required_payload"],
    "properties": {
            "emum_payload": {
            "type": "string",  # the user maybe specified a wrong type, eg: `str`
            "enum": ["enum_string_1", "enum_string_2"],
            "default": "enum_string_1"
        }
    }
}

here is detail:

[membphis]

we should use json here

[membphis]

this line should be wrong, it should be "enum":

[membphis]

json ditto

[moonming]

we can merge first, then fix minor issues.

#1881 fix later

[membphis]

@sshniro merged, many thx