Golang谷歌协议缓冲区中的错误。

huangapple
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英文:

Bug in golang google protocol buffer

问题

我有一个Python程序和一个Golang程序，都从一个socket获取数据。我打印出它们接收到的字节。

Python代码：

  1. Data = 0a300a084a6f686e20446f6510071a126a6f686e2e646f6540676d61696c2e636f6d220e0a0c3131312d3131312d31313130

Golang代码：

  1. 2016/04/02 23:21:08 50 bytes read from 192.168.0.1:65120
  2. 2016/04/02 23:21:08 00000000  0a 30 0a 08 4a 6f 68 6e  20 44 6f 65 10 08 1a 12  |.0..John Doe....|
  3. 00000010  6a 6f 68 6e 2e 64 6f 65  40 67 6d 61 69 6c 2e 63  |john.doe@gmail.c|
  4. 00000020  6f 6d 22 0e 0a 0c 31 31  31 2d 31 31 31 2d 31 31  |om"...111-111-11|
  5. 00000030  31 30                                             |10|

.proto文件在两者中是相同的。

  1. syntax = "proto3";
  2. package MC_Feed;
  4. message Person {
  5.   enum PhoneType {
  6.     MOBILE = 0;
  7.     HOME = 1;
  8.     WORK = 2;
  9.   }
  11.   string name = 1;
  12.   int32 id = 2;  // Unique ID number for this person.
  13.   string email = 3;
  15.   message PhoneNumber {
  16.     string number = 1;
  17.     PhoneType type = 2;
  18.   }
  20.   repeated PhoneNumber phones = 4;
  21. }
  23. // Our address book file is just one of these.
  24. message AddressBook {
  25.   repeated Person people = 1;
  26. }

在Python（以及C#）中，它可以正常工作。但在Golang方面，我得到了以下错误：

  1. 2016/04/02 23:21:08 proto: MC_Feed.AddressBook: illegal tag 0 (wire type 0)

这段Golang代码是我从网络上找到并稍作修改：

  1. package main
  3. import (
  4. 	"github.com/golang/protobuf/proto"
  5. 	"encoding/hex"
  6. 	"./Simple"
  7. 	"log"
  8. 	"net"
  9. )
  11. const (
  12. 	srvAddr         = "239.0.0.222:345"
  13. 	maxDatagramSize = 8192
  14. )
  16. func main() {
  17. 	serveMulticastUDP(srvAddr, msgHandler)
  18. }
  21. func msgHandler(src *net.UDPAddr, n int, b []byte) {
  22. 	log.Println(n, "bytes read from", src)
  23. 	log.Println(hex.Dump(b[:n]))
  24. 	newTest := &MC_Feed.AddressBook{}
  25.     err := proto.Unmarshal(b, newTest)
  26.     log.Println(err)
  27. }
  29. func serveMulticastUDP(a string, h func(*net.UDPAddr, int, []byte)) {
  30. 	addr, err := net.ResolveUDPAddr("udp", a)
  31. 	if err != nil {
  32. 		log.Fatal(err)
  33. 	}
  34. 	l, err := net.ListenMulticastUDP("udp", nil, addr)
  35. 	l.SetReadBuffer(maxDatagramSize)
  36. 	for {
  37. 		b := make([]byte, maxDatagramSize)
  38. 		n, src, err := l.ReadFromUDP(b)
  39. 		if err != nil {
  40. 			log.Fatal("ReadFromUDP failed:", err)
  41. 		}
  42. 		h(src, n, b)
  43. 	}
  44. }
英文:

I have a python program and a golang program both getting data from a socket. I print the bytes it receives from both.

  1. python
  3. Data = 0a300a084a6f686e20446f6510071a126a6f686e2e646f6540676d61696c2e636f6d220e0a0c3131312d3131312d31313130
  5. golang
  7. 2016/04/02 23:21:08 50 bytes read from 192.168.0.1:65120
  8. 2016/04/02 23:21:08 00000000  0a 30 0a 08 4a 6f 68 6e  20 44 6f 65 10 08 1a 12  |.0..John Doe....|
  9. 00000010  6a 6f 68 6e 2e 64 6f 65  40 67 6d 61 69 6c 2e 63  |john.doe@gmail.c|
  10. 00000020  6f 6d 22 0e 0a 0c 31 31  31 2d 31 31 31 2d 31 31  |om"...111-111-11|
  11. 00000030  31 30                                             |10|

The .proto file is identical in both.

  1. syntax = "proto3";
  2. package MC_Feed;
  4. message Person {
  5.   enum PhoneType {
  6.     MOBILE = 0;
  7.     HOME = 1;
  8.     WORK = 2;
  9.   }
  11.   string name = 1;
  12.   int32 id = 2;  // Unique ID number for this person.
  13.   string email = 3;
  15.   message PhoneNumber {
  16.     string number = 1;
  17.     PhoneType type = 2;
  18.   }
  20.   repeated PhoneNumber phones = 4;
  21. }
  23. // Our address book file is just one of these.
  24. message AddressBook {
  25.   repeated Person people = 1;
  26. }

On the python (and C# for that matter) it works fine. On the golang side, I get this error:

  1. 2016/04/02 23:21:08 proto: MC_Feed.AddressBook: illegal tag 0 (wire type 0)

The go code is something I got from the net and modified a little:

  1. package main
  3. import (
  4. 	"github.com/golang/protobuf/proto"
  5. 	"encoding/hex"
  6. 	"./Simple"
  7. 	"log"
  8. 	"net"
  9. )
  11. const (
  12. 	srvAddr         = "239.0.0.222:345"
  13. 	maxDatagramSize = 8192
  14. )
  16. func main() {
  17. 	serveMulticastUDP(srvAddr, msgHandler)
  18. }
  21. func msgHandler(src *net.UDPAddr, n int, b []byte) {
  22. 	log.Println(n, "bytes read from", src)
  23. 	log.Println(hex.Dump(b[:n]))
  24. 	newTest := &MC_Feed.AddressBook{}
  25.     err := proto.Unmarshal(b, newTest)
  26.     log.Println(err)
  27. }
  29. func serveMulticastUDP(a string, h func(*net.UDPAddr, int, []byte)) {
  30. 	addr, err := net.ResolveUDPAddr("udp", a)
  31. 	if err != nil {
  32. 		log.Fatal(err)
  33. 	}
  34. 	l, err := net.ListenMulticastUDP("udp", nil, addr)
  35. 	l.SetReadBuffer(maxDatagramSize)
  36. 	for {
  37. 		b := make([]byte, maxDatagramSize)
  38. 		n, src, err := l.ReadFromUDP(b)
  39. 		if err != nil {
  40. 			log.Fatal("ReadFromUDP failed:", err)
  41. 		}
  42. 		h(src, n, b)
  43. 	}
  44. }

答案1

得分: 6

您的缓冲区 b 的大小适合最大可能的数据报包，但其中并不全是您的消息，只有前 n 个字节是消息的一部分。关于 illegal tag 0 和 wire type 0 的错误是由于尝试解析您未初始化的缓冲区空间中的 0 字节而引起的。将 b[:n] 传递给 Unmarshal 函数以修复该问题。

英文:

Your buffer b is sized for the maximum possible datagram packet but not all of that is your message, only the first n bytes. The messages about illegal tag 0 and wire type 0 result from trying to parse the 0 bytes in buffer space you haven't otherwise initialized. Pass b[:n] to Unmarshal to fix.

huangapple
  • 本文由 发表于 2016年4月3日 11:26:04
  • 转载请务必保留本文链接：https://go.coder-hub.com/36381301.html
  • go
  • protocol-buffers
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