前言

上篇介紹了go-grpc-middleware的grpc_zap、grpc_auth和grpc_recovery使用，本篇將介紹grpc_validator，它可以對gRPC資料的輸入和輸出進行驗證。

建立proto檔案，新增驗證規則

這裡使用第三方外掛go-proto-validators自動生成驗證規則。

go get github.com/mwitkow/go-proto-validators

1.新建simple.proto檔案

syntax = "proto3";

package proto;

import "github.com/mwitkow/go-proto-validators/validator.proto";

message InnerMessage {
  // some_integer can only be in range (1, 100).
  int32 some_integer = 1 [(validator.field) = {int_gt: 0, int_lt: 100}];
  // some_float can only be in range (0;1).
  double some_float = 2 [(validator.field) = {float_gte: 0, float_lte: 1}];
}

message OuterMessage {
  // important_string must be a lowercase alpha-numeric of 5 to 30 characters (RE2 syntax).
  string important_string = 1 [(validator.field) = {regex: "^[a-z]{2,5}$"}];
  // proto3 doesn't have `required`, the `msg_exist` enforces presence of InnerMessage.
  InnerMessage inner = 2 [(validator.field) = {msg_exists : true}];
}

service Simple{
  rpc Route (InnerMessage) returns (OuterMessage){};
}
 

程式碼import "github.com/mwitkow/go-proto-validators/validator.proto"，檔案validator.proto需要import "google/protobuf/descriptor.proto";包，不然會報錯。

google/protobuf地址：https://github.com/protocolbuffers/protobuf/blob/master/src/google/protobuf/descriptor.proto。

把src資料夾中的protobuf目錄下載到GOPATH目錄下。

2.編譯simple.proto檔案

go get github.com/mwitkow/go-proto-validators/protoc-gen-govalidators

指令編譯：protoc --govalidators_out=. --go_out=plugins=grpc:./ ./simple.proto

或者使用VSCode-proto3外掛，第一篇有介紹。只需要新增"--govalidators_out=."即可。

    // vscode-proto3外掛配置
    "protoc": {
        // protoc.exe所在目錄
        "path": "C:\\Go\\bin\\protoc.exe",
        // 儲存時自動編譯
        "compile_on_save": true,
        "options": [
            // go編譯輸出指令
            "--go_out=plugins=grpc:.",
            "--govalidators_out=."
        ]
    },
 

編譯完成後，自動生成simple.pb.go和simple.validator.pb.go檔案，simple.pb.go檔案不再介紹，我們看下simple.validator.pb.go檔案。

// Code generated by protoc-gen-gogo. DO NOT EDIT.
// source: go-grpc-example/9-grpc_proto_validators/proto/simple.proto

package proto

import (
	fmt "fmt"
	math "math"
	proto "github.com/golang/protobuf/proto"
	_ "github.com/mwitkow/go-proto-validators"
	regexp "regexp"
	github_com_mwitkow_go_proto_validators "github.com/mwitkow/go-proto-validators"
)

// Reference imports to suppress errors if they are not otherwise used.
var _ = proto.Marshal
var _ = fmt.Errorf
var _ = math.Inf

func (this *InnerMessage) Validate() error {
	if !(this.SomeInteger > 0) {
		return github_com_mwitkow_go_proto_validators.FieldError("SomeInteger", fmt.Errorf(`value '%v' must be greater than '0'`, this.SomeInteger))
	}
	if !(this.SomeInteger < 100) {
		return github_com_mwitkow_go_proto_validators.FieldError("SomeInteger", fmt.Errorf(`value '%v' must be less than '100'`, this.SomeInteger))
	}
	if !(this.SomeFloat >= 0) {
		return github_com_mwitkow_go_proto_validators.FieldError("SomeFloat", fmt.Errorf(`value '%v' must be greater than or equal to '0'`, this.SomeFloat))
	}
	if !(this.SomeFloat <= 1) {
		return github_com_mwitkow_go_proto_validators.FieldError("SomeFloat", fmt.Errorf(`value '%v' must be lower than or equal to '1'`, this.SomeFloat))
	}
	return nil
}

var _regex_OuterMessage_ImportantString = regexp.MustCompile(`^[a-z]{2,5}$`)

func (this *OuterMessage) Validate() error {
	if !_regex_OuterMessage_ImportantString.MatchString(this.ImportantString) {
		return github_com_mwitkow_go_proto_validators.FieldError("ImportantString", fmt.Errorf(`value '%v' must be a string conforming to regex "^[a-z]{2,5}$"`, this.ImportantString))
	}
	if nil == this.Inner {
		return github_com_mwitkow_go_proto_validators.FieldError("Inner", fmt.Errorf("message must exist"))
	}
	if this.Inner != nil {
		if err := github_com_mwitkow_go_proto_validators.CallValidatorIfExists(this.Inner); err != nil {
			return github_com_mwitkow_go_proto_validators.FieldError("Inner", err)
		}
	}
	return nil
}

裡面自動生成了message中屬性的驗證規則。

把grpc_validator驗證攔截器新增到服務端

grpcServer := grpc.NewServer(cred.TLSInterceptor(),
	grpc.StreamInterceptor(grpc_middleware.ChainStreamServer(
			grpc_validator.StreamServerInterceptor(),
	        grpc_auth.StreamServerInterceptor(auth.AuthInterceptor),
			grpc_zap.StreamServerInterceptor(zap.ZapInterceptor()),
			grpc_recovery.StreamServerInterceptor(recovery.RecoveryInterceptor()),
		)),
		grpc.UnaryInterceptor(grpc_middleware.ChainUnaryServer(
		    grpc_validator.UnaryServerInterceptor(),
		    grpc_auth.UnaryServerInterceptor(auth.AuthInterceptor),
			grpc_zap.UnaryServerInterceptor(zap.ZapInterceptor()),
            grpc_recovery.UnaryServerInterceptor(recovery.RecoveryInterceptor()),
		)),
	)

執行後，當輸入資料驗證失敗後，會有以下錯誤返回

Call Route err: rpc error: code = InvalidArgument desc = invalid field SomeInteger: value '101' must be less than '100'

其他型別驗證規則設定

enum驗證

syntax = "proto3";
package proto;
import "github.com/mwitkow/go-proto-validators/validator.proto";

message SomeMsg {
  Action do = 1 [(validator.field) = {is_in_enum : true}];
}

enum Action {
  ALLOW = 0;
  DENY = 1;
  CHILL = 2;
}

UUID驗證

syntax = "proto3";
package proto;
import "github.com/mwitkow/go-proto-validators/validator.proto";

message UUIDMsg {
  // user_id must be a valid version 4 UUID.
  string user_id = 1 [(validator.field) = {uuid_ver: 4, string_not_empty: true}];
}

總結

go-grpc-middleware中grpc_validator整合go-proto-validators，我們只需要在編寫proto時設好驗證規則，並把grpc_validator新增到gRPC服務端，就能完成gRPC的資料驗證，很簡單也很方便。

教程原始碼地址：https://github.com/Bingjian-Zhu/go-grpc-exam