proto: StartGroup

[3052]

I see that StartGroup is not defined:

https://github.com/segmentio/encoding/blob/101dc9c5750213ca76cdac2fbc96d667f855555f/proto/message.go#L142-L149

I think this is a problem, as some servers are still using it, for example android.clients.google.com.

[3052]

Here is example program to demonstrate the problem:

package main
import "github.com/segmentio/encoding/proto"

var buf = []byte("\n\tPinterest\x18\x88\x80\xbd\x04\"\x069.38.0H\xb6Ƃ\x12R'android.permission.ACCESS_FINE_LOCATIONR'android.permission.ACCESS_NETWORK_STATER$android.permission.ACCESS_WIFI_STATER\x19android.permission.CAMERAR%android.permission.FOREGROUND_SERVICER\x1fandroid.permission.GET_ACCOUNTSR\x1bandroid.permission.INTERNETR\x16android.permission.NFCR android.permission.READ_CONTACTSR(android.permission.READ_EXTERNAL_STORAGER\x1fandroid.permission.READ_PROFILER)android.permission.RECEIVE_BOOT_COMPLETEDR\x1fandroid.permission.RECORD_AUDIOR android.permission.SET_WALLPAPERR\"android.permission.USE_CREDENTIALSR\x1aandroid.permission.VIBRATER\x1candroid.permission.WAKE_LOCKR)android.permission.WRITE_EXTERNAL_STORAGER*com.google.android.c2dm.permission.RECEIVERFcom.google.android.finsky.permission.BIND_GET_INSTALL_REFERRER_SERVICER:com.google.android.providers.gsf.permission.READ_GSERVICESR.com.sec.android.provider.badge.permission.READR/com.sec.android.provider.badge.permission.WRITEZ\[email protected]\x1ahttps://help.pinterest.comj\f500,000,000+r\rcom.pinterestz\x9e\x01Every week we polish up the Pinterest app to make it faster and better than ever. Tell us if you like this newest version at http://help.pinterest.com/contact\x82\x01\vNov 4, 2021\x8a\x01\f\b\x00\x10\x88\x80\xbd\x04\x18\x98\x94\xdb\t\x8a\x01\x18\b\x00\x10\x88\x80\xbd\x04\x18ך7\"\vconfig.ldpi\x8a\x01\x16\b\x00\x10\x88\x80\xbd\x04\x18\x99\x83.\"\tconfig.en\x8a\x01 \b\x00\x10\x88\x80\xbd\x04\x18\xae\x94\xc2\a\"\x12config.armeabi_v7a\xa8\x01\x01\xf2\x01\fContains ads\x92\x02\xb9\x02\x10\xb6Ƃ\x12\x1a#\n\x16com.google.android.gms\x10\xb8\xf9\xf7\x05 \x01(\x000\x01\x1a\x1d\n\x12com.google.ar.core\x10\x90\x88\x8ce(\x010\x02 \x1e(\x03P\x02Z\vconfig.ldpiZ\tconfig.enZ\x12config.armeabi_v7a\x8a\x01\xba\x01\n\xb7\x01AB-xQnrRjA2gOewRVcyJK8QVgDaEb9DrMSv_o5YK27xm4VQ55WGxNAm2hsEYREBVIe5Ja-VbVcukaq65AYBjwBCKHYXO76UTsel3YOHKrEygYroA7MpW5KvRV-s2onK8UkiulWIACDI1aftBYiQXO8UwKI2NF3JO0btX78F9tUfJ3KAFQYMYdfE\x9a\x02\x93\x01\x10\x00\x18\x00\b\x012~\b\x01*xhttps://play-lh.googleusercontent.com/DX5LZpc4SUuvYv2kLA31fi05liLQwizh4DbHYwQthmNP15rul46zG-aquf2Vaf3M9EeBIihWmCsyIWFSLQH\x01:\tPinterest@\x02\x9a\x01\x1btqdNvLiUsPc9jEhccusSR6jwJ8o\x80\x02\x1e\xf2\x02D\x12B\x1a)search?q=pub:Pinterest&o=0&c=3&ksm=1&sb=5P\x03Z\rpub:Pinterest\xf8\x01\x05\xb8\x03\x03\x82\x03\tLifestyle\xa8\x03\x80ʵ\xee\x01\xea\x03\x05500M+\x82\x04\x1c\n\fAug 14, 2012\x12\f\b\x98髁\x05\x10\xc0\x8b\xf6\x82\x02\x92\x04\x00\xa2\x04\v\n\tPinterest\xb0\x04\xd1\xd3¿\x02\xca\x04\b\n\x06\b\aB\x02\b\x03\xd2\x04\b\n\x06\b\aB\x02\b\x0e\xe2\x04\b\n\x06\b\aB\x02\b\x13\xea\x04\x04500M\xf2\x04\v500 million")

func main() {
   var appDetails struct {
      Version string `protobuf:"bytes,4"`
      Permission []string `protobuf:"bytes,10"`
   }
   proto.Unmarshal(buf, &appDetails)
}

Result:

panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xc0000005 code=0x0 addr=0x14 pc=0xa20d78]
goroutine 1 [running]:
github.com/segmentio/encoding/internal/runtime_reflect.CopySlice(...)
        C:/Users/Steven/go/pkg/mod/github.com/segmentio/[email protected]/internal/runtime_reflect/slice.go:36
github.com/segmentio/encoding/proto.growSlice({0xb07ba0, 0xab7be0}, 0xc0000764f0)
        C:/Users/Steven/go/pkg/mod/github.com/segmentio/[email protected]/proto/slice.go:139 +0x89
github.com/segmentio/encoding/proto.sliceDecodeFuncOf.func1({0xbb739a, 0x20, 0x660}, 0xc0000764f0, 0x0)
        C:/Users/Steven/go/pkg/mod/github.com/segmentio/[email protected]/proto/slice.go:108 +0x6d
github.com/segmentio/encoding/proto.structDecodeFuncOf.func1({0xbb7220, 0x7da, 0x7da}, 0xc0000764e0, 0x30)
        C:/Users/Steven/go/pkg/mod/github.com/segmentio/[email protected]/proto/struct.go:402 +0x64e
github.com/segmentio/encoding/proto.Unmarshal({0xbb7220, 0x7da, 0x7da}, {0xab4be0, 0xc0000764e0})
        C:/Users/Steven/go/pkg/mod/github.com/segmentio/[email protected]/proto/proto.go:49 +0x1d7