go-grpc-middleware/validator

请求验证器中间件验很重要，也很困难。它还会导致大量的样板代码。这个中间件检查gRPC请求的每个消息是否存在“Validate”方法。这包括“一元”调用的单个请求，以及入站流调用的每个消息。如果验证失败，则返回’ InvalidArgument ‘ gRPC状态，并描述验证失败。虽然它是通用的，它的目的是用于https://github.com/mwitkow/go-proto-validators，一个Go协议缓冲代码根插件

func StreamServerInterceptor() grpc.StreamServerInterceptor 服务端流拦截器
func UnaryServerInterceptor() grpc.UnaryServerInterceptor 服务端一元拦截器
func UnaryClientInterceptor() grpc.UnaryClientInterceptor 无效的消息将在发送请求到服务器之前被拒绝

官方例子

结合”github.com/mwitkow/go-proto-validators/validator.proto”来做

第一步：定义proto

syntax = "proto3";
package common;
import "github.com/mwitkow/go-proto-validators/validator.proto";
message Message {
  string important_string = 1 [
    (validator.field) = {regex: "^[a-z]{2,5}$"}
  ];
  int32 age = 2 [
    (validator.field) = {int_gt: 0, int_lt: 100}
  ];
}

在开源社区中，github.com/mwitkow/go-proto-validators 已经基于Protobuf的扩展特性实现了功能较为强大的验证器功能。要使用该验证器首先需要下载其提供的代码生成插件：

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

第二步：生成go文件

protoc  --proto_path=E:/go/src --proto_path=. --govalidators_out=. 
--go_out=plugins=grpc:. prorotest/protos/common/common.proto

报错：github.com/mwitkow/go-proto-validators/validator.proto: File not found.
提示找不到validator.proto，我们将这个项目clone下来，放到E:/go/src

再尝试生成，还是报错

google/protobuf/descriptor.proto: File not found.
github.com/mwitkow/go-proto-validators/validator.proto:12:1: Import "google/protobuf/descriptor.proto" was not found or had errors.
github.com/mwitkow/go-proto-validators/validator.proto:18:8: "google.protobuf.FieldOptions" is not defined.
github.com/mwitkow/go-proto-validators/validator.proto:22:8: "google.protobuf.OneofOptions" is not defined.
prorotest/protos/common/common.proto:5:1: Import "github.com/mwitkow/go-proto-validators/validator.proto" was not found or had errors.

这是因为validator.proto import了 google/protobuf/descriptor.proto

把所需的proto下载下来，https://github.com/protocolbuffers/protobuf/tree/master/src，同样放到E:/go/src下，注意命令规范google/protobuf

最后再生成

看看commom.validator.pb.go的内容

ps:如果生成命令为下面这样，是会报错的

protoc  --proto_path=E:/go/src --govalidators_out=. --go_out=plugins=grpc:. prorotest/protos/common/common.proto

这个与—proto_path参数有关，记住：如果引用了其他地方的proto，并且需要指定—proto_path，那么一定要多加上一个”—proto_path=.”

第三步：整合

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()),
        )),
    )

如果参数不符合，会返回如下错误

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

字段验证规则

message FieldValidator {
  // Uses a Golang RE2-syntax regex to match the field contents.
  optional string regex = 1;
  // Field value of integer strictly greater than this value.
  optional int64 int_gt = 2;
  // Field value of integer strictly smaller than this value.
  optional int64 int_lt = 3;
  // Used for nested message types, requires that the message type exists.
  optional bool msg_exists = 4;
  // Human error specifies a user-customizable error that is visible to the user.
  optional string human_error = 5;
  // Field value of double strictly greater than this value.
  // Note that this value can only take on a valid floating point
  // value. Use together with float_epsilon if you need something more specific.
  optional double float_gt = 6;
  // Field value of double strictly smaller than this value.
  // Note that this value can only take on a valid floating point
  // value. Use together with float_epsilon if you need something more specific.
  optional double float_lt = 7;
  // Field value of double describing the epsilon within which
  // any comparison should be considered to be true. For example,
  // when using float_gt = 0.35, using a float_epsilon of 0.05
  // would mean that any value above 0.30 is acceptable. It can be
  // thought of as a {float_value_condition} +- {float_epsilon}.
  // If unset, no correction for floating point inaccuracies in
  // comparisons will be attempted.
  optional double float_epsilon = 8;
  // Floating-point value compared to which the field content should be greater or equal.
  optional double float_gte = 9;
  // Floating-point value compared to which the field content should be smaller or equal.
  optional double float_lte = 10;
  // Used for string fields, requires the string to be not empty (i.e different from "").
  optional bool string_not_empty = 11;
  // Repeated field with at least this number of elements.
  optional int64 repeated_count_min = 12;
  // Repeated field with at most this number of elements.
  optional int64 repeated_count_max = 13;
  // Field value of length greater than this value.
  optional int64 length_gt = 14;
  // Field value of length smaller than this value.
  optional int64 length_lt = 15;
  // Field value of length strictly equal to this value.
  optional int64 length_eq = 16;
  // Requires that the value is in the enum.
  optional bool is_in_enum = 17;
  // Ensures that a string value is in UUID format.
  // uuid_ver specifies the valid UUID versions. Valid values are: 0-5.
  // If uuid_ver is 0 all UUID versions are accepted.
  optional int32 uuid_ver = 18;
}

enum验证

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验证

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}];
}

嵌套验证

syntax = "proto3";
package validator.examples;
import "github.com/mwitkow/go-proto-validators/validator.proto";
message InnerMessage {
  // some_integer can only be in range (0, 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-z0-9]{5,30}$"}];
  // proto3没有'required'， 使用msg_exist 验证InnerMessage
  InnerMessage inner = 2 [(validator.field) = {msg_exists : true}];
}

更好的选择

使用更多的验证中间件应该是protoc-gen-validate，https://www.yuque.com/jw-go/mqm3eb/slxava

看validator的源码
定义了一个validator接口，只要实现了该接口就行，正好protoc-gen-validate生成的验证代码实现了该接口，因此可直接使用

type validator interface {
    Validate() error
}
func UnaryServerInterceptor() grpc.UnaryServerInterceptor {
    return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
        if v, ok := req.(validator); ok {
            if err := v.Validate(); err != nil {
                return nil, status.Errorf(codes.InvalidArgument, err.Error())
            }
        }
        return handler(ctx, req)
    }
}

例子：
proto

syntax = "proto3";
package protobuf;
import "google/validate/validate.proto";
service pingService {
  rpc Ping(PingReq) returns (PingRsp){}
}
message PingReq {
  string ping = 1 [(validate.rules).string = {min_len: 2, max_len: 5}];
}
message PingRsp {
  string pong = 1;
}

client.go

package main
import (
    pb "commons/grpc/protobuf"
    "context"
    "fmt"
    "log"
    "google.golang.org/grpc"
)
func main() {
    conn, err := grpc.Dial("127.0.0.1:8888", grpc.WithInsecure())
    if err != nil {
        fmt.Printf("did not connect: %v", err)
    }
    defer conn.Close()
    client := pb.NewPingServiceClient(conn)
    rsp, err := client.Ping(context.Background(), &pb.PingReq{
        Ping: "x",
    })
    if err != nil {
        log.Fatalf("err: %v", err)
    }
    fmt.Println(rsp.Pong)
}

service.go

package main
import (
    "context"
    "log"
    "net"
    pb "commons/grpc/protobuf"
    grpc_middleware "github.com/grpc-ecosystem/go-grpc-middleware"
    grpc_validator "github.com/grpc-ecosystem/go-grpc-middleware/validator"
    "google.golang.org/grpc"
)
func main() {
    lis, err := net.Listen("tcp", ":8888")
    if err != nil {
        log.Fatalf("failed to listen: %v", err)
    }
    var grpcServer = grpc.NewServer(
        grpc.UnaryInterceptor(grpc_middleware.ChainUnaryServer(
            grpc_validator.UnaryServerInterceptor(),
        )),
    )
    pb.RegisterPingServiceServer(grpcServer, &S{})
    if err := grpcServer.Serve(lis); err != nil {
        log.Fatalf("failed to serve: %v", err)
    }
}
type S struct {
}
func (s S) Ping(ctx context.Context, req *pb.PingReq) (*pb.PingRsp, error) {
    return &pb.PingRsp{Pong: req.Ping}, nil
}

如果参数不符合，会返回以下错误：

err: rpc error: code = InvalidArgument desc = invalid PingReq.Ping: value length must be between 2 and 5 runes, inclusive