NETOBSERV-212 (I): basic protobuf definition and generation

Makefile

@@ -20,6 +20,7 @@ GOLANGCI_LINT_VERSION = v1.42.1
 CLANG ?= clang
 CFLAGS := -O2 -g -Wall -Werror $(CFLAGS)
 GOOS := linux
+PROTOC_ARTIFACTS := pkg/pbflow
 
 # Image building tool (docker / podman)
 ifeq (,$(shell which podman 2>/dev/null))
@@ -38,6 +39,7 @@ prereqs:
 	@echo "### Check if prerequisites are met, and installing missing dependencies"
 	test -f $(go env GOPATH)/bin/golangci-lint || GOFLAGS="" go install github.com/golangci/golangci-lint/cmd/golangci-lint@${GOLANGCI_LINT_VERSION}
 	test -f $(go env GOPATH)/bin/bpf2go || go install github.com/cilium/ebpf/cmd/bpf2go@${CILIUM_EBPF_VERSION}
+	test -f $(go env GOPATH)/bin/protoc-gen-go || go install google.golang.org/protobuf/cmd/protoc-gen-go@latest
 
 .PHONY: fmt
 fmt: ## Run go fmt against code.
@@ -49,20 +51,22 @@ lint: prereqs
 	@echo "### Linting code"
 	golangci-lint run ./...
 
-# As generated artifacts are part of the code repo (pkg/ebpf package) you don't have to run this
-# for each build. Only when you change the C code inside the bpf folder
-# You might need to use the docker-generate target instead of this
+# As generated artifacts are part of the code repo (pkg/ebpf and pkg/proto packages), you don't have
+# to run this target for each build. Only when you change the C code inside the bpf folder or the
+# protobuf definitions in the proto folder.
+# You might want to use the docker-generate target instead of this.
 .PHONY: generate
 generate: export BPF_CLANG := $(CLANG)
 generate: export BPF_CFLAGS := $(CFLAGS)
 generate: prereqs
 	@echo "### Generating BPF Go bindings"
 	go generate ./pkg/...
+	protoc --go_out=pkg proto/flow.proto
 
 .PHONY: docker-generate
 docker-generate:
 	@echo "### Creating the container that generates the eBPF binaries"
-	docker build . -f scripts/Dockerfile_ebpf_generator -t $(LOCAL_GENERATOR_IMAGE)
+	docker build . -f scripts/Dockerfile_generators -t $(LOCAL_GENERATOR_IMAGE)
 	docker run --rm -v $(shell pwd):/src $(LOCAL_GENERATOR_IMAGE)
 
 .PHONY: build

bpf/flows.c

@@ -29,23 +29,23 @@ static inline int fill_iphdr(struct iphdr *ip, void *data_end, struct flow *flow
         return DISCARD;
     }
 
-    flow->network.src_ip = __bpf_htonl(ip->saddr);
-    flow->network.dst_ip = __bpf_htonl(ip->daddr);
+    flow->network.src_ip = __bpf_ntohl(ip->saddr);
+    flow->network.dst_ip = __bpf_ntohl(ip->daddr);
     flow->transport.protocol = ip->protocol;
 
     switch (ip->protocol) {
     case IPPROTO_TCP: {
         struct tcphdr *tcp = (void *)ip + sizeof(*ip);
         if ((void *)tcp + sizeof(*tcp) <= data_end) {
-            flow->transport.src_port = __bpf_htons(tcp->source);
-            flow->transport.dst_port = __bpf_htons(tcp->dest);
+            flow->transport.src_port = __bpf_ntohs(tcp->source);
+            flow->transport.dst_port = __bpf_ntohs(tcp->dest);
         }
     } break;
     case IPPROTO_UDP: {
         struct udphdr *udp = (void *)ip + sizeof(*ip);
         if ((void *)udp + sizeof(*udp) <= data_end) {
-            flow->transport.src_port = __bpf_htons(udp->source);
-            flow->transport.dst_port = __bpf_htons(udp->dest);
+            flow->transport.src_port = __bpf_ntohs(udp->source);
+            flow->transport.dst_port = __bpf_ntohs(udp->dest);
         }
     } break;
     default:
@@ -61,9 +61,9 @@ static inline int fill_ethhdr(struct ethhdr *eth, void *data_end, struct flow *f
     }
     __builtin_memcpy(flow->data_link.dst_mac, eth->h_dest, ETH_ALEN);
     __builtin_memcpy(flow->data_link.src_mac, eth->h_source, ETH_ALEN);
-    flow->protocol = eth->h_proto;
+    flow->protocol = __bpf_ntohs(eth->h_proto);
     // TODO: ETH_P_IPV6
-    if (flow->protocol == __bpf_constant_ntohs(ETH_P_IP)) {
+    if (flow->protocol == ETH_P_IP) {
         struct iphdr *ip = (void *)eth + sizeof(*eth);
         return fill_iphdr(ip, data_end, flow);
     }

go.mod

@@ -8,6 +8,7 @@ require (
 	github.com/sirupsen/logrus v1.8.1
 	github.com/stretchr/testify v1.7.0
 	github.com/vishvananda/netlink v1.1.0
+	google.golang.org/protobuf v1.27.1
 )
 
 require (

go.sum

@@ -6,6 +6,8 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/frankban/quicktest v1.14.0 h1:+cqqvzZV87b4adx/5ayVOaYZ2CrvM4ejQvUdBzPPUss=
 github.com/frankban/quicktest v1.14.0/go.mod h1:NeW+ay9A/U67EYXNFA1nPE8e/tnQv/09mUdL/ijj8og=
+github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaSAoJOfIk=
+github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.6 h1:BKbKCqvP6I+rmFHt06ZmyQtvB8xAkWdhFyr0ZUNZcxQ=
 github.com/google/go-cmp v0.5.6/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
@@ -37,6 +39,9 @@ golang.org/x/sys v0.0.0-20210906170528-6f6e22806c34 h1:GkvMjFtXUmahfDtashnc1mnrC
 golang.org/x/sys v0.0.0-20210906170528-6f6e22806c34/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp09yW+WbY/TyQbw=
+google.golang.org/protobuf v1.27.1 h1:SnqbnDw1V7RiZcXPx5MEeqPv2s79L9i7BJUlG/+RurQ=
+google.golang.org/protobuf v1.27.1/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQnmE0givc=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=

proto/flow.proto

+syntax = "proto3";
+
+package pbflow;
+
+import 'google/protobuf/timestamp.proto';
+
+option go_package = "./pbflow";
+
+message Records {
+  repeated Record entries = 1;
+}
+
+message Record {
+  message DataLink {
+    uint64 src_mac = 1;
+    uint64 dst_mac = 2;
+  }
+  message Network {
+    message IP {
+      oneof ip_family {
+        fixed32 ipv4 = 1;
+        bytes ipv6 = 2;
+      }
+    }
+    IP src_addr = 1;
+    IP dst_addr = 2;
+  }
+  message Transport {
+    uint32 src_port = 1;
+    uint32 dst_port = 2;
+    // protocol as defined by IPPROTO_* in linux/in.h
+    // https://github.com/torvalds/linux/blob/master/include/uapi/linux/in.h
+    uint32 protocol = 3;
+  }
+  // as defined by field 61 in
+  // https://www.iana.org/assignments/ipfix/ipfix.xhtml
+  enum Direction {
+    INGRESS = 0;
+    EGRESS = 1;
+  }
+  // protocol as defined by ETH_P_* in linux/if_ether.h
+  // https://github.com/torvalds/linux/blob/master/include/uapi/linux/if_ether.h
+  uint32 eth_protocol = 1;
+  Direction direction = 2;
+  google.protobuf.Timestamp time_flow_start = 3;
+  google.protobuf.Timestamp time_flow_end = 4;
+
+  // OSI-layer attributes
+  DataLink data_link = 5;
+  Network network = 6;
+  Transport transport = 7;
+
+  uint64 bytes = 8;
+  uint64 packets = 9;
+}
\ No newline at end of file

scripts/Dockerfile_ebpf_generator → scripts/Dockerfile_generators

 FROM fedora:35
 
 ARG GOVERSION="1.17.8"
+ARG PROTOCVERSION="3.19.4"
 
 # Installs dependencies that are required to compile eBPF programs
-RUN dnf install -y kernel-devel make llvm clang glibc-devel.i686
+RUN dnf install -y kernel-devel make llvm clang glibc-devel.i686 unzip
 RUN dnf clean all
 
 VOLUME ["/src"]
@@ -18,10 +19,18 @@ RUN rm go.tar.gz
 ENV GOROOT /go
 RUN mkdir -p /gopath
 ENV GOPATH /gopath
-ENV PATH $GOROOT/bin:$GOPATH/bin:$PATH
 
-WORKDIR /tmp
+RUN mkdir -p /protoc
+WORKDIR /protoc
+
+# Installs Protoc compiler
+RUN curl -qL https://github.com/protocolbuffers/protobuf/releases/download/v$PROTOCVERSION/protoc-${PROTOCVERSION}-linux-x86_64.zip -o protoc.zip
+RUN unzip protoc.zip
+RUN rm protoc.zip
 
+ENV PATH $GOROOT/bin:$GOPATH/bin:/protoc/bin:$PATH
+
+WORKDIR /tmp
 # Copies some pre-required Go dependencies to avoid downloading them on each build
 COPY Makefile Makefile
 RUN make prereqs

scripts/README.md

@@ -5,7 +5,7 @@
 Fetches the BPF headers and places them in the `bpf/headers` folder. You don't need
 to run this script unless you want to e.g. update any of them to a newer version.
 
-# `Dockerfile_ebpf_generator`
+# `Dockerfile_generators`
 
-Dockerfile for the eBPF binaries generator. It is invoked from the root `Makefile`, in the
-`make docker-generate` target.
+Dockerfile for the eBPF binaries and Protobuf implementation generator. It is invoked from the root
+`Makefile`, in the `make docker-generate` target.
\ No newline at end of file

vendor/google.golang.org/protobuf/AUTHORS

+# This source code refers to The Go Authors for copyright purposes.
+# The master list of authors is in the main Go distribution,
+# visible at https://tip.golang.org/AUTHORS.

vendor/google.golang.org/protobuf/CONTRIBUTORS

+# This source code was written by the Go contributors.
+# The master list of contributors is in the main Go distribution,
+# visible at https://tip.golang.org/CONTRIBUTORS.

vendor/google.golang.org/protobuf/LICENSE

+Copyright (c) 2018 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

vendor/google.golang.org/protobuf/PATENTS

+Additional IP Rights Grant (Patents)
+
+"This implementation" means the copyrightable works distributed by
+Google as part of the Go project.
+
+Google hereby grants to You a perpetual, worldwide, non-exclusive,
+no-charge, royalty-free, irrevocable (except as stated in this section)
+patent license to make, have made, use, offer to sell, sell, import,
+transfer and otherwise run, modify and propagate the contents of this
+implementation of Go, where such license applies only to those patent
+claims, both currently owned or controlled by Google and acquired in
+the future, licensable by Google that are necessarily infringed by this
+implementation of Go.  This grant does not include claims that would be
+infringed only as a consequence of further modification of this
+implementation.  If you or your agent or exclusive licensee institute or
+order or agree to the institution of patent litigation against any
+entity (including a cross-claim or counterclaim in a lawsuit) alleging
+that this implementation of Go or any code incorporated within this
+implementation of Go constitutes direct or contributory patent
+infringement, or inducement of patent infringement, then any patent
+rights granted to you under this License for this implementation of Go
+shall terminate as of the date such litigation is filed.

vendor/google.golang.org/protobuf/encoding/prototext/doc.go

+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package prototext marshals and unmarshals protocol buffer messages as the
+// textproto format.
+package prototext

vendor/google.golang.org/protobuf/encoding/prototext/encode.go

+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package prototext
+
+import (
+	"fmt"
+	"strconv"
+	"unicode/utf8"
+
+	"google.golang.org/protobuf/encoding/protowire"
+	"google.golang.org/protobuf/internal/encoding/messageset"
+	"google.golang.org/protobuf/internal/encoding/text"
+	"google.golang.org/protobuf/internal/errors"
+	"google.golang.org/protobuf/internal/flags"
+	"google.golang.org/protobuf/internal/genid"
+	"google.golang.org/protobuf/internal/order"
+	"google.golang.org/protobuf/internal/pragma"
+	"google.golang.org/protobuf/internal/strs"
+	"google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/reflect/protoreflect"
+	pref "google.golang.org/protobuf/reflect/protoreflect"
+	"google.golang.org/protobuf/reflect/protoregistry"
+)
+
+const defaultIndent = "  "
+
+// Format formats the message as a multiline string.
+// This function is only intended for human consumption and ignores errors.
+// Do not depend on the output being stable. It may change over time across
+// different versions of the program.
+func Format(m proto.Message) string {
+	return MarshalOptions{Multiline: true}.Format(m)
+}
+
+// Marshal writes the given proto.Message in textproto format using default
+// options. Do not depend on the output being stable. It may change over time
+// across different versions of the program.
+func Marshal(m proto.Message) ([]byte, error) {
+	return MarshalOptions{}.Marshal(m)
+}
+
+// MarshalOptions is a configurable text format marshaler.
+type MarshalOptions struct {
+	pragma.NoUnkeyedLiterals
+
+	// Multiline specifies whether the marshaler should format the output in
+	// indented-form with every textual element on a new line.
+	// If Indent is an empty string, then an arbitrary indent is chosen.
+	Multiline bool
+
+	// Indent specifies the set of indentation characters to use in a multiline
+	// formatted output such that every entry is preceded by Indent and
+	// terminated by a newline. If non-empty, then Multiline is treated as true.
+	// Indent can only be composed of space or tab characters.
+	Indent string
+
+	// EmitASCII specifies whether to format strings and bytes as ASCII only
+	// as opposed to using UTF-8 encoding when possible.
+	EmitASCII bool
+
+	// allowInvalidUTF8 specifies whether to permit the encoding of strings
+	// with invalid UTF-8. This is unexported as it is intended to only
+	// be specified by the Format method.
+	allowInvalidUTF8 bool
+
+	// AllowPartial allows messages that have missing required fields to marshal
+	// without returning an error. If AllowPartial is false (the default),
+	// Marshal will return error if there are any missing required fields.
+	AllowPartial bool
+
+	// EmitUnknown specifies whether to emit unknown fields in the output.
+	// If specified, the unmarshaler may be unable to parse the output.
+	// The default is to exclude unknown fields.
+	EmitUnknown bool
+
+	// Resolver is used for looking up types when expanding google.protobuf.Any
+	// messages. If nil, this defaults to using protoregistry.GlobalTypes.
+	Resolver interface {
+		protoregistry.ExtensionTypeResolver
+		protoregistry.MessageTypeResolver
+	}
+}
+
+// Format formats the message as a string.
+// This method is only intended for human consumption and ignores errors.
+// Do not depend on the output being stable. It may change over time across
+// different versions of the program.
+func (o MarshalOptions) Format(m proto.Message) string {
+	if m == nil || !m.ProtoReflect().IsValid() {
+		return "<nil>" // invalid syntax, but okay since this is for debugging
+	}
+	o.allowInvalidUTF8 = true
+	o.AllowPartial = true
+	o.EmitUnknown = true
+	b, _ := o.Marshal(m)
+	return string(b)
+}
+
+// Marshal writes the given proto.Message in textproto format using options in
+// MarshalOptions object. Do not depend on the output being stable. It may
+// change over time across different versions of the program.
+func (o MarshalOptions) Marshal(m proto.Message) ([]byte, error) {
+	return o.marshal(m)
+}
+
+// marshal is a centralized function that all marshal operations go through.
+// For profiling purposes, avoid changing the name of this function or
+// introducing other code paths for marshal that do not go through this.
+func (o MarshalOptions) marshal(m proto.Message) ([]byte, error) {
+	var delims = [2]byte{'{', '}'}
+
+	if o.Multiline && o.Indent == "" {
+		o.Indent = defaultIndent
+	}
+	if o.Resolver == nil {
+		o.Resolver = protoregistry.GlobalTypes
+	}
+
+	internalEnc, err := text.NewEncoder(o.Indent, delims, o.EmitASCII)
+	if err != nil {
+		return nil, err
+	}
+
+	// Treat nil message interface as an empty message,
+	// in which case there is nothing to output.
+	if m == nil {
+		return []byte{}, nil
+	}
+
+	enc := encoder{internalEnc, o}
+	err = enc.marshalMessage(m.ProtoReflect(), false)
+	if err != nil {
+		return nil, err
+	}
+	out := enc.Bytes()
+	if len(o.Indent) > 0 && len(out) > 0 {
+		out = append(out, '\n')
+	}
+	if o.AllowPartial {
+		return out, nil
+	}
+	return out, proto.CheckInitialized(m)
+}
+
+type encoder struct {
+	*text.Encoder
+	opts MarshalOptions
+}
+
+// marshalMessage marshals the given protoreflect.Message.
+func (e encoder) marshalMessage(m pref.Message, inclDelims bool) error {
+	messageDesc := m.Descriptor()
+	if !flags.ProtoLegacy && messageset.IsMessageSet(messageDesc) {
+		return errors.New("no support for proto1 MessageSets")
+	}
+
+	if inclDelims {
+		e.StartMessage()
+		defer e.EndMessage()
+	}
+
+	// Handle Any expansion.
+	if messageDesc.FullName() == genid.Any_message_fullname {
+		if e.marshalAny(m) {
+			return nil
+		}
+		// If unable to expand, continue on to marshal Any as a regular message.
+	}
+
+	// Marshal fields.
+	var err error
+	order.RangeFields(m, order.IndexNameFieldOrder, func(fd protoreflect.FieldDescriptor, v protoreflect.Value) bool {
+		if err = e.marshalField(fd.TextName(), v, fd); err != nil {
+			return false
+		}
+		return true
+	})
+	if err != nil {
+		return err
+	}
+
+	// Marshal unknown fields.
+	if e.opts.EmitUnknown {
+		e.marshalUnknown(m.GetUnknown())
+	}
+
+	return nil
+}
+
+// marshalField marshals the given field with protoreflect.Value.
+func (e encoder) marshalField(name string, val pref.Value, fd pref.FieldDescriptor) error {
+	switch {
+	case fd.IsList():
+		return e.marshalList(name, val.List(), fd)
+	case fd.IsMap():
+		return e.marshalMap(name, val.Map(), fd)
+	default:
+		e.WriteName(name)
+		return e.marshalSingular(val, fd)
+	}
+}
+
+// marshalSingular marshals the given non-repeated field value. This includes
+// all scalar types, enums, messages, and groups.
+func (e encoder) marshalSingular(val pref.Value, fd pref.FieldDescriptor) error {
+	kind := fd.Kind()
+	switch kind {
+	case pref.BoolKind:
+		e.WriteBool(val.Bool())
+
+	case pref.StringKind:
+		s := val.String()
+		if !e.opts.allowInvalidUTF8 && strs.EnforceUTF8(fd) && !utf8.ValidString(s) {
+			return errors.InvalidUTF8(string(fd.FullName()))
+		}
+		e.WriteString(s)
+
+	case pref.Int32Kind, pref.Int64Kind,
+		pref.Sint32Kind, pref.Sint64Kind,
+		pref.Sfixed32Kind, pref.Sfixed64Kind:
+		e.WriteInt(val.Int())
+
+	case pref.Uint32Kind, pref.Uint64Kind,
+		pref.Fixed32Kind, pref.Fixed64Kind:
+		e.WriteUint(val.Uint())
+
+	case pref.FloatKind:
+		// Encoder.WriteFloat handles the special numbers NaN and infinites.
+		e.WriteFloat(val.Float(), 32)
+
+	case pref.DoubleKind:
+		// Encoder.WriteFloat handles the special numbers NaN and infinites.
+		e.WriteFloat(val.Float(), 64)
+
+	case pref.BytesKind:
+		e.WriteString(string(val.Bytes()))
+
+	case pref.EnumKind:
+		num := val.Enum()
+		if desc := fd.Enum().Values().ByNumber(num); desc != nil {
+			e.WriteLiteral(string(desc.Name()))
+		} else {
+			// Use numeric value if there is no enum description.
+			e.WriteInt(int64(num))
+		}
+
+	case pref.MessageKind, pref.GroupKind:
+		return e.marshalMessage(val.Message(), true)
+
+	default:
+		panic(fmt.Sprintf("%v has unknown kind: %v", fd.FullName(), kind))
+	}
+	return nil
+}
+
+// marshalList marshals the given protoreflect.List as multiple name-value fields.
+func (e encoder) marshalList(name string, list pref.List, fd pref.FieldDescriptor) error {
+	size := list.Len()
+	for i := 0; i < size; i++ {
+		e.WriteName(name)
+		if err := e.marshalSingular(list.Get(i), fd); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// marshalMap marshals the given protoreflect.Map as multiple name-value fields.
+func (e encoder) marshalMap(name string, mmap pref.Map, fd pref.FieldDescriptor) error {
+	var err error
+	order.RangeEntries(mmap, order.GenericKeyOrder, func(key pref.MapKey, val pref.Value) bool {
+		e.WriteName(name)
+		e.StartMessage()
+		defer e.EndMessage()
+
+		e.WriteName(string(genid.MapEntry_Key_field_name))
+		err = e.marshalSingular(key.Value(), fd.MapKey())
+		if err != nil {
+			return false
+		}
+
+		e.WriteName(string(genid.MapEntry_Value_field_name))
+		err = e.marshalSingular(val, fd.MapValue())
+		if err != nil {
+			return false
+		}
+		return true
+	})
+	return err
+}
+
+// marshalUnknown parses the given []byte and marshals fields out.
+// This function assumes proper encoding in the given []byte.
+func (e encoder) marshalUnknown(b []byte) {
+	const dec = 10
+	const hex = 16
+	for len(b) > 0 {
+		num, wtype, n := protowire.ConsumeTag(b)
+		b = b[n:]
+		e.WriteName(strconv.FormatInt(int64(num), dec))
+
+		switch wtype {
+		case protowire.VarintType:
+			var v uint64
+			v, n = protowire.ConsumeVarint(b)
+			e.WriteUint(v)
+		case protowire.Fixed32Type:
+			var v uint32
+			v, n = protowire.ConsumeFixed32(b)
+			e.WriteLiteral("0x" + strconv.FormatUint(uint64(v), hex))
+		case protowire.Fixed64Type:
+			var v uint64
+			v, n = protowire.ConsumeFixed64(b)
+			e.WriteLiteral("0x" + strconv.FormatUint(v, hex))
+		case protowire.BytesType:
+			var v []byte
+			v, n = protowire.ConsumeBytes(b)
+			e.WriteString(string(v))
+		case protowire.StartGroupType:
+			e.StartMessage()
+			var v []byte
+			v, n = protowire.ConsumeGroup(num, b)
+			e.marshalUnknown(v)
+			e.EndMessage()
+		default:
+			panic(fmt.Sprintf("prototext: error parsing unknown field wire type: %v", wtype))
+		}
+
+		b = b[n:]
+	}
+}
+
+// marshalAny marshals the given google.protobuf.Any message in expanded form.
+// It returns true if it was able to marshal, else false.
+func (e encoder) marshalAny(any pref.Message) bool {
+	// Construct the embedded message.
+	fds := any.Descriptor().Fields()
+	fdType := fds.ByNumber(genid.Any_TypeUrl_field_number)
+	typeURL := any.Get(fdType).String()
+	mt, err := e.opts.Resolver.FindMessageByURL(typeURL)
+	if err != nil {
+		return false
+	}
+	m := mt.New().Interface()
+
+	// Unmarshal bytes into embedded message.
+	fdValue := fds.ByNumber(genid.Any_Value_field_number)
+	value := any.Get(fdValue)
+	err = proto.UnmarshalOptions{
+		AllowPartial: true,
+		Resolver:     e.opts.Resolver,
+	}.Unmarshal(value.Bytes(), m)
+	if err != nil {
+		return false
+	}
+
+	// Get current encoder position. If marshaling fails, reset encoder output
+	// back to this position.
+	pos := e.Snapshot()
+
+	// Field name is the proto field name enclosed in [].
+	e.WriteName("[" + typeURL + "]")
+	err = e.marshalMessage(m.ProtoReflect(), true)
+	if err != nil {
+		e.Reset(pos)
+		return false
+	}
+	return true
+}

vendor/google.golang.org/protobuf/encoding/protowire/wire.go

+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package protowire parses and formats the raw wire encoding.
+// See https://developers.google.com/protocol-buffers/docs/encoding.
+//
+// For marshaling and unmarshaling entire protobuf messages,
+// use the "google.golang.org/protobuf/proto" package instead.
+package protowire
+
+import (
+	"io"
+	"math"
+	"math/bits"
+
+	"google.golang.org/protobuf/internal/errors"
+)
+
+// Number represents the field number.
+type Number int32
+
+const (
+	MinValidNumber      Number = 1
+	FirstReservedNumber Number = 19000
+	LastReservedNumber  Number = 19999
+	MaxValidNumber      Number = 1<<29 - 1
+)
+
+// IsValid reports whether the field number is semantically valid.
+//
+// Note that while numbers within the reserved range are semantically invalid,
+// they are syntactically valid in the wire format.
+// Implementations may treat records with reserved field numbers as unknown.
+func (n Number) IsValid() bool {
+	return MinValidNumber <= n && n < FirstReservedNumber || LastReservedNumber < n && n <= MaxValidNumber
+}
+
+// Type represents the wire type.
+type Type int8
+
+const (
+	VarintType     Type = 0
+	Fixed32Type    Type = 5
+	Fixed64Type    Type = 1
+	BytesType      Type = 2
+	StartGroupType Type = 3
+	EndGroupType   Type = 4
+)
+
+const (
+	_ = -iota
+	errCodeTruncated
+	errCodeFieldNumber
+	errCodeOverflow
+	errCodeReserved
+	errCodeEndGroup
+)
+
+var (
+	errFieldNumber = errors.New("invalid field number")
+	errOverflow    = errors.New("variable length integer overflow")
+	errReserved    = errors.New("cannot parse reserved wire type")
+	errEndGroup    = errors.New("mismatching end group marker")
+	errParse       = errors.New("parse error")
+)
+
+// ParseError converts an error code into an error value.
+// This returns nil if n is a non-negative number.
+func ParseError(n int) error {
+	if n >= 0 {
+		return nil
+	}
+	switch n {
+	case errCodeTruncated:
+		return io.ErrUnexpectedEOF
+	case errCodeFieldNumber:
+		return errFieldNumber
+	case errCodeOverflow:
+		return errOverflow
+	case errCodeReserved:
+		return errReserved
+	case errCodeEndGroup:
+		return errEndGroup
+	default:
+		return errParse
+	}
+}
+
+// ConsumeField parses an entire field record (both tag and value) and returns
+// the field number, the wire type, and the total length.
+// This returns a negative length upon an error (see ParseError).
+//
+// The total length includes the tag header and the end group marker (if the
+// field is a group).
+func ConsumeField(b []byte) (Number, Type, int) {
+	num, typ, n := ConsumeTag(b)
+	if n < 0 {
+		return 0, 0, n // forward error code
+	}
+	m := ConsumeFieldValue(num, typ, b[n:])
+	if m < 0 {
+		return 0, 0, m // forward error code
+	}
+	return num, typ, n + m
+}
+
+// ConsumeFieldValue parses a field value and returns its length.
+// This assumes that the field Number and wire Type have already been parsed.
+// This returns a negative length upon an error (see ParseError).
+//
+// When parsing a group, the length includes the end group marker and
+// the end group is verified to match the starting field number.
+func ConsumeFieldValue(num Number, typ Type, b []byte) (n int) {
+	switch typ {
+	case VarintType:
+		_, n = ConsumeVarint(b)
+		return n
+	case Fixed32Type:
+		_, n = ConsumeFixed32(b)
+		return n
+	case Fixed64Type:
+		_, n = ConsumeFixed64(b)
+		return n
+	case BytesType:
+		_, n = ConsumeBytes(b)
+		return n
+	case StartGroupType:
+		n0 := len(b)
+		for {
+			num2, typ2, n := ConsumeTag(b)
+			if n < 0 {
+				return n // forward error code
+			}
+			b = b[n:]
+			if typ2 == EndGroupType {
+				if num != num2 {
+					return errCodeEndGroup
+				}
+				return n0 - len(b)
+			}
+
+			n = ConsumeFieldValue(num2, typ2, b)
+			if n < 0 {
+				return n // forward error code
+			}
+			b = b[n:]
+		}
+	case EndGroupType:
+		return errCodeEndGroup
+	default:
+		return errCodeReserved
+	}
+}
+
+// AppendTag encodes num and typ as a varint-encoded tag and appends it to b.
+func AppendTag(b []byte, num Number, typ Type) []byte {
+	return AppendVarint(b, EncodeTag(num, typ))
+}
+
+// ConsumeTag parses b as a varint-encoded tag, reporting its length.
+// This returns a negative length upon an error (see ParseError).
+func ConsumeTag(b []byte) (Number, Type, int) {
+	v, n := ConsumeVarint(b)
+	if n < 0 {
+		return 0, 0, n // forward error code
+	}
+	num, typ := DecodeTag(v)
+	if num < MinValidNumber {
+		return 0, 0, errCodeFieldNumber
+	}
+	return num, typ, n
+}
+
+func SizeTag(num Number) int {
+	return SizeVarint(EncodeTag(num, 0)) // wire type has no effect on size
+}
+
+// AppendVarint appends v to b as a varint-encoded uint64.
+func AppendVarint(b []byte, v uint64) []byte {
+	switch {
+	case v < 1<<7:
+		b = append(b, byte(v))
+	case v < 1<<14:
+		b = append(b,
+			byte((v>>0)&0x7f|0x80),
+			byte(v>>7))
+	case v < 1<<21:
+		b = append(b,
+			byte((v>>0)&0x7f|0x80),
+			byte((v>>7)&0x7f|0x80),
+			byte(v>>14))
+	case v < 1<<28:
+		b = append(b,
+			byte((v>>0)&0x7f|0x80),
+			byte((v>>7)&0x7f|0x80),
+			byte((v>>14)&0x7f|0x80),
+			byte(v>>21))
+	case v < 1<<35:
+		b = append(b,
+			byte((v>>0)&0x7f|0x80),
+			byte((v>>7)&0x7f|0x80),
+			byte((v>>14)&0x7f|0x80),
+			byte((v>>21)&0x7f|0x80),
+			byte(v>>28))
+	case v < 1<<42:
+		b = append(b,
+			byte((v>>0)&0x7f|0x80),
+			byte((v>>7)&0x7f|0x80),
+			byte((v>>14)&0x7f|0x80),
+			byte((v>>21)&0x7f|0x80),
+			byte((v>>28)&0x7f|0x80),
+			byte(v>>35))
+	case v < 1<<49:
+		b = append(b,
+			byte((v>>0)&0x7f|0x80),
+			byte((v>>7)&0x7f|0x80),
+			byte((v>>14)&0x7f|0x80),
+			byte((v>>21)&0x7f|0x80),
+			byte((v>>28)&0x7f|0x80),
+			byte((v>>35)&0x7f|0x80),
+			byte(v>>42))
+	case v < 1<<56:
+		b = append(b,
+			byte((v>>0)&0x7f|0x80),
+			byte((v>>7)&0x7f|0x80),
+			byte((v>>14)&0x7f|0x80),
+			byte((v>>21)&0x7f|0x80),
+			byte((v>>28)&0x7f|0x80),
+			byte((v>>35)&0x7f|0x80),
+			byte((v>>42)&0x7f|0x80),
+			byte(v>>49))
+	case v < 1<<63:
+		b = append(b,
+			byte((v>>0)&0x7f|0x80),
+			byte((v>>7)&0x7f|0x80),
+			byte((v>>14)&0x7f|0x80),
+			byte((v>>21)&0x7f|0x80),
+			byte((v>>28)&0x7f|0x80),
+			byte((v>>35)&0x7f|0x80),
+			byte((v>>42)&0x7f|0x80),
+			byte((v>>49)&0x7f|0x80),
+			byte(v>>56))
+	default:
+		b = append(b,
+			byte((v>>0)&0x7f|0x80),
+			byte((v>>7)&0x7f|0x80),
+			byte((v>>14)&0x7f|0x80),
+			byte((v>>21)&0x7f|0x80),
+			byte((v>>28)&0x7f|0x80),
+			byte((v>>35)&0x7f|0x80),
+			byte((v>>42)&0x7f|0x80),
+			byte((v>>49)&0x7f|0x80),
+			byte((v>>56)&0x7f|0x80),
+			1)
+	}
+	return b
+}
+
+// ConsumeVarint parses b as a varint-encoded uint64, reporting its length.
+// This returns a negative length upon an error (see ParseError).
+func ConsumeVarint(b []byte) (v uint64, n int) {
+	var y uint64
+	if len(b) <= 0 {
+		return 0, errCodeTruncated
+	}
+	v = uint64(b[0])
+	if v < 0x80 {
+		return v, 1
+	}
+	v -= 0x80
+
+	if len(b) <= 1 {
+		return 0, errCodeTruncated
+	}
+	y = uint64(b[1])
+	v += y << 7
+	if y < 0x80 {
+		return v, 2
+	}
+	v -= 0x80 << 7
+
+	if len(b) <= 2 {
+		return 0, errCodeTruncated
+	}
+	y = uint64(b[2])
+	v += y << 14
+	if y < 0x80 {
+		return v, 3
+	}
+	v -= 0x80 << 14
+
+	if len(b) <= 3 {
+		return 0, errCodeTruncated
+	}
+	y = uint64(b[3])
+	v += y << 21
+	if y < 0x80 {
+		return v, 4
+	}
+	v -= 0x80 << 21
+
+	if len(b) <= 4 {
+		return 0, errCodeTruncated
+	}
+	y = uint64(b[4])
+	v += y << 28
+	if y < 0x80 {
+		return v, 5
+	}
+	v -= 0x80 << 28
+
+	if len(b) <= 5 {
+		return 0, errCodeTruncated
+	}
+	y = uint64(b[5])
+	v += y << 35
+	if y < 0x80 {
+		return v, 6
+	}
+	v -= 0x80 << 35
+
+	if len(b) <= 6 {
+		return 0, errCodeTruncated
+	}
+	y = uint64(b[6])
+	v += y << 42
+	if y < 0x80 {
+		return v, 7
+	}
+	v -= 0x80 << 42
+
+	if len(b) <= 7 {
+		return 0, errCodeTruncated
+	}
+	y = uint64(b[7])
+	v += y << 49
+	if y < 0x80 {
+		return v, 8
+	}
+	v -= 0x80 << 49
+
+	if len(b) <= 8 {
+		return 0, errCodeTruncated
+	}
+	y = uint64(b[8])
+	v += y << 56
+	if y < 0x80 {
+		return v, 9
+	}
+	v -= 0x80 << 56
+
+	if len(b) <= 9 {
+		return 0, errCodeTruncated
+	}
+	y = uint64(b[9])
+	v += y << 63
+	if y < 2 {
+		return v, 10
+	}
+	return 0, errCodeOverflow
+}
+
+// SizeVarint returns the encoded size of a varint.
+// The size is guaranteed to be within 1 and 10, inclusive.
+func SizeVarint(v uint64) int {
+	// This computes 1 + (bits.Len64(v)-1)/7.
+	// 9/64 is a good enough approximation of 1/7
+	return int(9*uint32(bits.Len64(v))+64) / 64
+}
+
+// AppendFixed32 appends v to b as a little-endian uint32.
+func AppendFixed32(b []byte, v uint32) []byte {
+	return append(b,
+		byte(v>>0),
+		byte(v>>8),
+		byte(v>>16),
+		byte(v>>24))
+}
+
+// ConsumeFixed32 parses b as a little-endian uint32, reporting its length.
+// This returns a negative length upon an error (see ParseError).
+func ConsumeFixed32(b []byte) (v uint32, n int) {
+	if len(b) < 4 {
+		return 0, errCodeTruncated
+	}
+	v = uint32(b[0])<<0 | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
+	return v, 4
+}
+
+// SizeFixed32 returns the encoded size of a fixed32; which is always 4.
+func SizeFixed32() int {
+	return 4
+}
+
+// AppendFixed64 appends v to b as a little-endian uint64.
+func AppendFixed64(b []byte, v uint64) []byte {
+	return append(b,
+		byte(v>>0),
+		byte(v>>8),
+		byte(v>>16),
+		byte(v>>24),
+		byte(v>>32),
+		byte(v>>40),
+		byte(v>>48),
+		byte(v>>56))
+}
+
+// ConsumeFixed64 parses b as a little-endian uint64, reporting its length.
+// This returns a negative length upon an error (see ParseError).
+func ConsumeFixed64(b []byte) (v uint64, n int) {
+	if len(b) < 8 {
+		return 0, errCodeTruncated
+	}
+	v = uint64(b[0])<<0 | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 | uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
+	return v, 8
+}
+
+// SizeFixed64 returns the encoded size of a fixed64; which is always 8.
+func SizeFixed64() int {
+	return 8
+}
+
+// AppendBytes appends v to b as a length-prefixed bytes value.
+func AppendBytes(b []byte, v []byte) []byte {
+	return append(AppendVarint(b, uint64(len(v))), v...)
+}
+
+// ConsumeBytes parses b as a length-prefixed bytes value, reporting its length.
+// This returns a negative length upon an error (see ParseError).
+func ConsumeBytes(b []byte) (v []byte, n int) {
+	m, n := ConsumeVarint(b)
+	if n < 0 {
+		return nil, n // forward error code
+	}
+	if m > uint64(len(b[n:])) {
+		return nil, errCodeTruncated
+	}
+	return b[n:][:m], n + int(m)
+}
+
+// SizeBytes returns the encoded size of a length-prefixed bytes value,
+// given only the length.
+func SizeBytes(n int) int {
+	return SizeVarint(uint64(n)) + n
+}
+
+// AppendString appends v to b as a length-prefixed bytes value.
+func AppendString(b []byte, v string) []byte {
+	return append(AppendVarint(b, uint64(len(v))), v...)
+}
+
+// ConsumeString parses b as a length-prefixed bytes value, reporting its length.
+// This returns a negative length upon an error (see ParseError).
+func ConsumeString(b []byte) (v string, n int) {
+	bb, n := ConsumeBytes(b)
+	return string(bb), n
+}
+
+// AppendGroup appends v to b as group value, with a trailing end group marker.
+// The value v must not contain the end marker.
+func AppendGroup(b []byte, num Number, v []byte) []byte {
+	return AppendVarint(append(b, v...), EncodeTag(num, EndGroupType))
+}
+
+// ConsumeGroup parses b as a group value until the trailing end group marker,
+// and verifies that the end marker matches the provided num. The value v
+// does not contain the end marker, while the length does contain the end marker.
+// This returns a negative length upon an error (see ParseError).
+func ConsumeGroup(num Number, b []byte) (v []byte, n int) {
+	n = ConsumeFieldValue(num, StartGroupType, b)
+	if n < 0 {
+		return nil, n // forward error code
+	}
+	b = b[:n]
+
+	// Truncate off end group marker, but need to handle denormalized varints.
+	// Assuming end marker is never 0 (which is always the case since
+	// EndGroupType is non-zero), we can truncate all trailing bytes where the
+	// lower 7 bits are all zero (implying that the varint is denormalized).
+	for len(b) > 0 && b[len(b)-1]&0x7f == 0 {
+		b = b[:len(b)-1]
+	}
+	b = b[:len(b)-SizeTag(num)]
+	return b, n
+}
+
+// SizeGroup returns the encoded size of a group, given only the length.
+func SizeGroup(num Number, n int) int {
+	return n + SizeTag(num)
+}
+
+// DecodeTag decodes the field Number and wire Type from its unified form.
+// The Number is -1 if the decoded field number overflows int32.
+// Other than overflow, this does not check for field number validity.
+func DecodeTag(x uint64) (Number, Type) {
+	// NOTE: MessageSet allows for larger field numbers than normal.
+	if x>>3 > uint64(math.MaxInt32) {
+		return -1, 0
+	}
+	return Number(x >> 3), Type(x & 7)
+}
+
+// EncodeTag encodes the field Number and wire Type into its unified form.
+func EncodeTag(num Number, typ Type) uint64 {
+	return uint64(num)<<3 | uint64(typ&7)
+}
+
+// DecodeZigZag decodes a zig-zag-encoded uint64 as an int64.
+//	Input:  {…,  5,  3,  1,  0,  2,  4,  6, …}
+//	Output: {…, -3, -2, -1,  0, +1, +2, +3, …}
+func DecodeZigZag(x uint64) int64 {
+	return int64(x>>1) ^ int64(x)<<63>>63
+}
+
+// EncodeZigZag encodes an int64 as a zig-zag-encoded uint64.
+//	Input:  {…, -3, -2, -1,  0, +1, +2, +3, …}
+//	Output: {…,  5,  3,  1,  0,  2,  4,  6, …}
+func EncodeZigZag(x int64) uint64 {
+	return uint64(x<<1) ^ uint64(x>>63)
+}
+
+// DecodeBool decodes a uint64 as a bool.
+//	Input:  {    0,    1,    2, …}
+//	Output: {false, true, true, …}
+func DecodeBool(x uint64) bool {
+	return x != 0
+}
+
+// EncodeBool encodes a bool as a uint64.
+//	Input:  {false, true}
+//	Output: {    0,    1}
+func EncodeBool(x bool) uint64 {
+	if x {
+		return 1
+	}
+	return 0
+}

vendor/google.golang.org/protobuf/internal/descfmt/stringer.go

+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package descfmt provides functionality to format descriptors.
+package descfmt
+
+import (
+	"fmt"
+	"io"
+	"reflect"
+	"strconv"
+	"strings"
+
+	"google.golang.org/protobuf/internal/detrand"
+	"google.golang.org/protobuf/internal/pragma"
+	pref "google.golang.org/protobuf/reflect/protoreflect"
+)
+
+type list interface {
+	Len() int
+	pragma.DoNotImplement
+}
+
+func FormatList(s fmt.State, r rune, vs list) {
+	io.WriteString(s, formatListOpt(vs, true, r == 'v' && (s.Flag('+') || s.Flag('#'))))
+}
+func formatListOpt(vs list, isRoot, allowMulti bool) string {
+	start, end := "[", "]"
+	if isRoot {
+		var name string
+		switch vs.(type) {
+		case pref.Names:
+			name = "Names"
+		case pref.FieldNumbers:
+			name = "FieldNumbers"
+		case pref.FieldRanges:
+			name = "FieldRanges"
+		case pref.EnumRanges:
+			name = "EnumRanges"
+		case pref.FileImports:
+			name = "FileImports"
+		case pref.Descriptor:
+			name = reflect.ValueOf(vs).MethodByName("Get").Type().Out(0).Name() + "s"
+		default:
+			name = reflect.ValueOf(vs).Elem().Type().Name()
+		}
+		start, end = name+"{", "}"
+	}
+
+	var ss []string
+	switch vs := vs.(type) {
+	case pref.Names:
+		for i := 0; i < vs.Len(); i++ {
+			ss = append(ss, fmt.Sprint(vs.Get(i)))
+		}
+		return start + joinStrings(ss, false) + end
+	case pref.FieldNumbers:
+		for i := 0; i < vs.Len(); i++ {
+			ss = append(ss, fmt.Sprint(vs.Get(i)))
+		}
+		return start + joinStrings(ss, false) + end
+	case pref.FieldRanges:
+		for i := 0; i < vs.Len(); i++ {
+			r := vs.Get(i)
+			if r[0]+1 == r[1] {
+				ss = append(ss, fmt.Sprintf("%d", r[0]))
+			} else {
+				ss = append(ss, fmt.Sprintf("%d:%d", r[0], r[1])) // enum ranges are end exclusive
+			}
+		}
+		return start + joinStrings(ss, false) + end
+	case pref.EnumRanges:
+		for i := 0; i < vs.Len(); i++ {
+			r := vs.Get(i)
+			if r[0] == r[1] {
+				ss = append(ss, fmt.Sprintf("%d", r[0]))
+			} else {
+				ss = append(ss, fmt.Sprintf("%d:%d", r[0], int64(r[1])+1)) // enum ranges are end inclusive
+			}
+		}
+		return start + joinStrings(ss, false) + end
+	case pref.FileImports:
+		for i := 0; i < vs.Len(); i++ {
+			var rs records
+			rs.Append(reflect.ValueOf(vs.Get(i)), "Path", "Package", "IsPublic", "IsWeak")
+			ss = append(ss, "{"+rs.Join()+"}")
+		}
+		return start + joinStrings(ss, allowMulti) + end
+	default:
+		_, isEnumValue := vs.(pref.EnumValueDescriptors)
+		for i := 0; i < vs.Len(); i++ {
+			m := reflect.ValueOf(vs).MethodByName("Get")
+			v := m.Call([]reflect.Value{reflect.ValueOf(i)})[0].Interface()
+			ss = append(ss, formatDescOpt(v.(pref.Descriptor), false, allowMulti && !isEnumValue))
+		}
+		return start + joinStrings(ss, allowMulti && isEnumValue) + end
+	}
+}
+
+// descriptorAccessors is a list of accessors to print for each descriptor.
+//
+// Do not print all accessors since some contain redundant information,
+// while others are pointers that we do not want to follow since the descriptor
+// is actually a cyclic graph.
+//
+// Using a list allows us to print the accessors in a sensible order.
+var descriptorAccessors = map[reflect.Type][]string{
+	reflect.TypeOf((*pref.FileDescriptor)(nil)).Elem():      {"Path", "Package", "Imports", "Messages", "Enums", "Extensions", "Services"},
+	reflect.TypeOf((*pref.MessageDescriptor)(nil)).Elem():   {"IsMapEntry", "Fields", "Oneofs", "ReservedNames", "ReservedRanges", "RequiredNumbers", "ExtensionRanges", "Messages", "Enums", "Extensions"},
+	reflect.TypeOf((*pref.FieldDescriptor)(nil)).Elem():     {"Number", "Cardinality", "Kind", "HasJSONName", "JSONName", "HasPresence", "IsExtension", "IsPacked", "IsWeak", "IsList", "IsMap", "MapKey", "MapValue", "HasDefault", "Default", "ContainingOneof", "ContainingMessage", "Message", "Enum"},
+	reflect.TypeOf((*pref.OneofDescriptor)(nil)).Elem():     {"Fields"}, // not directly used; must keep in sync with formatDescOpt
+	reflect.TypeOf((*pref.EnumDescriptor)(nil)).Elem():      {"Values", "ReservedNames", "ReservedRanges"},
+	reflect.TypeOf((*pref.EnumValueDescriptor)(nil)).Elem(): {"Number"},
+	reflect.TypeOf((*pref.ServiceDescriptor)(nil)).Elem():   {"Methods"},
+	reflect.TypeOf((*pref.MethodDescriptor)(nil)).Elem():    {"Input", "Output", "IsStreamingClient", "IsStreamingServer"},
+}
+
+func FormatDesc(s fmt.State, r rune, t pref.Descriptor) {
+	io.WriteString(s, formatDescOpt(t, true, r == 'v' && (s.Flag('+') || s.Flag('#'))))
+}
+func formatDescOpt(t pref.Descriptor, isRoot, allowMulti bool) string {
+	rv := reflect.ValueOf(t)
+	rt := rv.MethodByName("ProtoType").Type().In(0)
+
+	start, end := "{", "}"
+	if isRoot {
+		start = rt.Name() + "{"
+	}
+
+	_, isFile := t.(pref.FileDescriptor)
+	rs := records{allowMulti: allowMulti}
+	if t.IsPlaceholder() {
+		if isFile {
+			rs.Append(rv, "Path", "Package", "IsPlaceholder")
+		} else {
+			rs.Append(rv, "FullName", "IsPlaceholder")
+		}
+	} else {
+		switch {
+		case isFile:
+			rs.Append(rv, "Syntax")
+		case isRoot:
+			rs.Append(rv, "Syntax", "FullName")
+		default:
+			rs.Append(rv, "Name")
+		}
+		switch t := t.(type) {
+		case pref.FieldDescriptor:
+			for _, s := range descriptorAccessors[rt] {
+				switch s {
+				case "MapKey":
+					if k := t.MapKey(); k != nil {
+						rs.recs = append(rs.recs, [2]string{"MapKey", k.Kind().String()})
+					}
+				case "MapValue":
+					if v := t.MapValue(); v != nil {
+						switch v.Kind() {
+						case pref.EnumKind:
+							rs.recs = append(rs.recs, [2]string{"MapValue", string(v.Enum().FullName())})
+						case pref.MessageKind, pref.GroupKind:
+							rs.recs = append(rs.recs, [2]string{"MapValue", string(v.Message().FullName())})
+						default:
+							rs.recs = append(rs.recs, [2]string{"MapValue", v.Kind().String()})
+						}
+					}
+				case "ContainingOneof":
+					if od := t.ContainingOneof(); od != nil {
+						rs.recs = append(rs.recs, [2]string{"Oneof", string(od.Name())})
+					}
+				case "ContainingMessage":
+					if t.IsExtension() {
+						rs.recs = append(rs.recs, [2]string{"Extendee", string(t.ContainingMessage().FullName())})
+					}
+				case "Message":
+					if !t.IsMap() {
+						rs.Append(rv, s)
+					}
+				default:
+					rs.Append(rv, s)
+				}
+			}
+		case pref.OneofDescriptor:
+			var ss []string
+			fs := t.Fields()
+			for i := 0; i < fs.Len(); i++ {
+				ss = append(ss, string(fs.Get(i).Name()))
+			}
+			if len(ss) > 0 {
+				rs.recs = append(rs.recs, [2]string{"Fields", "[" + joinStrings(ss, false) + "]"})
+			}
+		default:
+			rs.Append(rv, descriptorAccessors[rt]...)
+		}
+		if rv.MethodByName("GoType").IsValid() {
+			rs.Append(rv, "GoType")
+		}
+	}
+	return start + rs.Join() + end
+}
+
+type records struct {
+	recs       [][2]string
+	allowMulti bool
+}
+
+func (rs *records) Append(v reflect.Value, accessors ...string) {
+	for _, a := range accessors {
+		var rv reflect.Value
+		if m := v.MethodByName(a); m.IsValid() {
+			rv = m.Call(nil)[0]
+		}
+		if v.Kind() == reflect.Struct && !rv.IsValid() {
+			rv = v.FieldByName(a)
+		}
+		if !rv.IsValid() {
+			panic(fmt.Sprintf("unknown accessor: %v.%s", v.Type(), a))
+		}
+		if _, ok := rv.Interface().(pref.Value); ok {
+			rv = rv.MethodByName("Interface").Call(nil)[0]
+			if !rv.IsNil() {
+				rv = rv.Elem()
+			}
+		}
+
+		// Ignore zero values.
+		var isZero bool
+		switch rv.Kind() {
+		case reflect.Interface, reflect.Slice:
+			isZero = rv.IsNil()
+		case reflect.Bool:
+			isZero = rv.Bool() == false
+		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+			isZero = rv.Int() == 0
+		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+			isZero = rv.Uint() == 0
+		case reflect.String:
+			isZero = rv.String() == ""
+		}
+		if n, ok := rv.Interface().(list); ok {
+			isZero = n.Len() == 0
+		}
+		if isZero {
+			continue
+		}
+
+		// Format the value.
+		var s string
+		v := rv.Interface()
+		switch v := v.(type) {
+		case list:
+			s = formatListOpt(v, false, rs.allowMulti)
+		case pref.FieldDescriptor, pref.OneofDescriptor, pref.EnumValueDescriptor, pref.MethodDescriptor:
+			s = string(v.(pref.Descriptor).Name())
+		case pref.Descriptor:
+			s = string(v.FullName())
+		case string:
+			s = strconv.Quote(v)
+		case []byte:
+			s = fmt.Sprintf("%q", v)
+		default:
+			s = fmt.Sprint(v)
+		}
+		rs.recs = append(rs.recs, [2]string{a, s})
+	}
+}
+
+func (rs *records) Join() string {
+	var ss []string
+
+	// In single line mode, simply join all records with commas.
+	if !rs.allowMulti {
+		for _, r := range rs.recs {
+			ss = append(ss, r[0]+formatColon(0)+r[1])
+		}
+		return joinStrings(ss, false)
+	}
+
+	// In allowMulti line mode, align single line records for more readable output.
+	var maxLen int
+	flush := func(i int) {
+		for _, r := range rs.recs[len(ss):i] {
+			ss = append(ss, r[0]+formatColon(maxLen-len(r[0]))+r[1])
+		}
+		maxLen = 0
+	}
+	for i, r := range rs.recs {
+		if isMulti := strings.Contains(r[1], "\n"); isMulti {
+			flush(i)
+			ss = append(ss, r[0]+formatColon(0)+strings.Join(strings.Split(r[1], "\n"), "\n\t"))
+		} else if maxLen < len(r[0]) {
+			maxLen = len(r[0])
+		}
+	}
+	flush(len(rs.recs))
+	return joinStrings(ss, true)
+}
+
+func formatColon(padding int) string {
+	// Deliberately introduce instability into the debug output to
+	// discourage users from performing string comparisons.
+	// This provides us flexibility to change the output in the future.
+	if detrand.Bool() {
+		return ":" + strings.Repeat(" ", 1+padding) // use non-breaking spaces (U+00a0)
+	} else {
+		return ":" + strings.Repeat(" ", 1+padding) // use regular spaces (U+0020)
+	}
+}
+
+func joinStrings(ss []string, isMulti bool) string {
+	if len(ss) == 0 {
+		return ""
+	}
+	if isMulti {
+		return "\n\t" + strings.Join(ss, "\n\t") + "\n"
+	}
+	return strings.Join(ss, ", ")
+}

vendor/google.golang.org/protobuf/internal/descopts/options.go

+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package descopts contains the nil pointers to concrete descriptor options.
+//
+// This package exists as a form of reverse dependency injection so that certain
+// packages (e.g., internal/filedesc and internal/filetype can avoid a direct
+// dependency on the descriptor proto package).
+package descopts
+
+import pref "google.golang.org/protobuf/reflect/protoreflect"
+
+// These variables are set by the init function in descriptor.pb.go via logic
+// in internal/filetype. In other words, so long as the descriptor proto package
+// is linked in, these variables will be populated.
+//
+// Each variable is populated with a nil pointer to the options struct.
+var (
+	File           pref.ProtoMessage
+	Enum           pref.ProtoMessage
+	EnumValue      pref.ProtoMessage
+	Message        pref.ProtoMessage
+	Field          pref.ProtoMessage
+	Oneof          pref.ProtoMessage
+	ExtensionRange pref.ProtoMessage
+	Service        pref.ProtoMessage
+	Method         pref.ProtoMessage
+)