Scott Baker | 1fe7273 | 2019-10-21 10:58:51 -0700 | [diff] [blame] | 1 | // Go support for Protocol Buffers - Google's data interchange format |
| 2 | // |
| 3 | // Copyright 2010 The Go Authors. All rights reserved. |
| 4 | // https://github.com/golang/protobuf |
| 5 | // |
| 6 | // Redistribution and use in source and binary forms, with or without |
| 7 | // modification, are permitted provided that the following conditions are |
| 8 | // met: |
| 9 | // |
| 10 | // * Redistributions of source code must retain the above copyright |
| 11 | // notice, this list of conditions and the following disclaimer. |
| 12 | // * Redistributions in binary form must reproduce the above |
| 13 | // copyright notice, this list of conditions and the following disclaimer |
| 14 | // in the documentation and/or other materials provided with the |
| 15 | // distribution. |
| 16 | // * Neither the name of Google Inc. nor the names of its |
| 17 | // contributors may be used to endorse or promote products derived from |
| 18 | // this software without specific prior written permission. |
| 19 | // |
| 20 | // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 21 | // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 22 | // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| 23 | // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| 24 | // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 25 | // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| 26 | // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 27 | // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 28 | // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 29 | // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| 30 | // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 31 | |
| 32 | package proto |
| 33 | |
| 34 | /* |
| 35 | * Support for message sets. |
| 36 | */ |
| 37 | |
| 38 | import ( |
| 39 | "errors" |
| 40 | ) |
| 41 | |
| 42 | // errNoMessageTypeID occurs when a protocol buffer does not have a message type ID. |
| 43 | // A message type ID is required for storing a protocol buffer in a message set. |
| 44 | var errNoMessageTypeID = errors.New("proto does not have a message type ID") |
| 45 | |
| 46 | // The first two types (_MessageSet_Item and messageSet) |
| 47 | // model what the protocol compiler produces for the following protocol message: |
| 48 | // message MessageSet { |
| 49 | // repeated group Item = 1 { |
| 50 | // required int32 type_id = 2; |
| 51 | // required string message = 3; |
| 52 | // }; |
| 53 | // } |
| 54 | // That is the MessageSet wire format. We can't use a proto to generate these |
| 55 | // because that would introduce a circular dependency between it and this package. |
| 56 | |
| 57 | type _MessageSet_Item struct { |
| 58 | TypeId *int32 `protobuf:"varint,2,req,name=type_id"` |
| 59 | Message []byte `protobuf:"bytes,3,req,name=message"` |
| 60 | } |
| 61 | |
| 62 | type messageSet struct { |
| 63 | Item []*_MessageSet_Item `protobuf:"group,1,rep"` |
| 64 | XXX_unrecognized []byte |
| 65 | // TODO: caching? |
| 66 | } |
| 67 | |
| 68 | // Make sure messageSet is a Message. |
| 69 | var _ Message = (*messageSet)(nil) |
| 70 | |
| 71 | // messageTypeIder is an interface satisfied by a protocol buffer type |
| 72 | // that may be stored in a MessageSet. |
| 73 | type messageTypeIder interface { |
| 74 | MessageTypeId() int32 |
| 75 | } |
| 76 | |
| 77 | func (ms *messageSet) find(pb Message) *_MessageSet_Item { |
| 78 | mti, ok := pb.(messageTypeIder) |
| 79 | if !ok { |
| 80 | return nil |
| 81 | } |
| 82 | id := mti.MessageTypeId() |
| 83 | for _, item := range ms.Item { |
| 84 | if *item.TypeId == id { |
| 85 | return item |
| 86 | } |
| 87 | } |
| 88 | return nil |
| 89 | } |
| 90 | |
| 91 | func (ms *messageSet) Has(pb Message) bool { |
| 92 | return ms.find(pb) != nil |
| 93 | } |
| 94 | |
| 95 | func (ms *messageSet) Unmarshal(pb Message) error { |
| 96 | if item := ms.find(pb); item != nil { |
| 97 | return Unmarshal(item.Message, pb) |
| 98 | } |
| 99 | if _, ok := pb.(messageTypeIder); !ok { |
| 100 | return errNoMessageTypeID |
| 101 | } |
| 102 | return nil // TODO: return error instead? |
| 103 | } |
| 104 | |
| 105 | func (ms *messageSet) Marshal(pb Message) error { |
| 106 | msg, err := Marshal(pb) |
| 107 | if err != nil { |
| 108 | return err |
| 109 | } |
| 110 | if item := ms.find(pb); item != nil { |
| 111 | // reuse existing item |
| 112 | item.Message = msg |
| 113 | return nil |
| 114 | } |
| 115 | |
| 116 | mti, ok := pb.(messageTypeIder) |
| 117 | if !ok { |
| 118 | return errNoMessageTypeID |
| 119 | } |
| 120 | |
| 121 | mtid := mti.MessageTypeId() |
| 122 | ms.Item = append(ms.Item, &_MessageSet_Item{ |
| 123 | TypeId: &mtid, |
| 124 | Message: msg, |
| 125 | }) |
| 126 | return nil |
| 127 | } |
| 128 | |
| 129 | func (ms *messageSet) Reset() { *ms = messageSet{} } |
| 130 | func (ms *messageSet) String() string { return CompactTextString(ms) } |
| 131 | func (*messageSet) ProtoMessage() {} |
| 132 | |
| 133 | // Support for the message_set_wire_format message option. |
| 134 | |
| 135 | func skipVarint(buf []byte) []byte { |
| 136 | i := 0 |
| 137 | for ; buf[i]&0x80 != 0; i++ { |
| 138 | } |
| 139 | return buf[i+1:] |
| 140 | } |
| 141 | |
| 142 | // unmarshalMessageSet decodes the extension map encoded in buf in the message set wire format. |
| 143 | // It is called by Unmarshal methods on protocol buffer messages with the message_set_wire_format option. |
| 144 | func unmarshalMessageSet(buf []byte, exts interface{}) error { |
| 145 | var m map[int32]Extension |
| 146 | switch exts := exts.(type) { |
| 147 | case *XXX_InternalExtensions: |
| 148 | m = exts.extensionsWrite() |
| 149 | case map[int32]Extension: |
| 150 | m = exts |
| 151 | default: |
| 152 | return errors.New("proto: not an extension map") |
| 153 | } |
| 154 | |
| 155 | ms := new(messageSet) |
| 156 | if err := Unmarshal(buf, ms); err != nil { |
| 157 | return err |
| 158 | } |
| 159 | for _, item := range ms.Item { |
| 160 | id := *item.TypeId |
| 161 | msg := item.Message |
| 162 | |
| 163 | // Restore wire type and field number varint, plus length varint. |
| 164 | // Be careful to preserve duplicate items. |
| 165 | b := EncodeVarint(uint64(id)<<3 | WireBytes) |
| 166 | if ext, ok := m[id]; ok { |
| 167 | // Existing data; rip off the tag and length varint |
| 168 | // so we join the new data correctly. |
| 169 | // We can assume that ext.enc is set because we are unmarshaling. |
| 170 | o := ext.enc[len(b):] // skip wire type and field number |
| 171 | _, n := DecodeVarint(o) // calculate length of length varint |
| 172 | o = o[n:] // skip length varint |
| 173 | msg = append(o, msg...) // join old data and new data |
| 174 | } |
| 175 | b = append(b, EncodeVarint(uint64(len(msg)))...) |
| 176 | b = append(b, msg...) |
| 177 | |
| 178 | m[id] = Extension{enc: b} |
| 179 | } |
| 180 | return nil |
| 181 | } |