internal/encoding/wire: increase maximum field number
The protobuf documentation explicitly specifies (1<<29)-1 as the maximum
field number, but the C++ implementation itself has a special-case where it
allows field numbers up to MaxInt32 for MessageSet fields, but continues
to apply the former limit in all non-MessageSet cases.
To avoid complicated branching logic, we use the larger limit for all cases
if MessageSet is supported, otherwise, we impose the documented limit.
Change-Id: I710a2a21aa3beba161c3e6ca2f2ed9a266920a5a
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/175817
Reviewed-by: Damien Neil <dneil@google.com>
diff --git a/internal/encoding/wire/wire.go b/internal/encoding/wire/wire.go
index 033b4c0..0706234 100644
--- a/internal/encoding/wire/wire.go
+++ b/internal/encoding/wire/wire.go
@@ -9,9 +9,11 @@
import (
"io"
+ "math"
"math/bits"
"github.com/golang/protobuf/v2/internal/errors"
+ "github.com/golang/protobuf/v2/internal/flags"
)
// Number represents the field number.
@@ -479,11 +481,17 @@
// The Number is -1 if the decoded field number overflows.
// Other than overflow, this does not check for field number validity.
func DecodeTag(x uint64) (Number, Type) {
- num := Number(x >> 3)
- if num > MaxValidNumber {
- num = -1
+ // NOTE: MessageSet allows for larger field numbers than normal.
+ if flags.Proto1Legacy {
+ if x>>3 > uint64(math.MaxInt32) {
+ return -1, 0
+ }
+ } else {
+ if x>>3 > uint64(MaxValidNumber) {
+ return -1, 0
+ }
}
- return num, Type(x & 7)
+ return Number(x >> 3), Type(x & 7)
}
// EncodeTag encodes the field Number and wire Type into its unified form.
diff --git a/internal/encoding/wire/wire_test.go b/internal/encoding/wire/wire_test.go
index 01e4d34..f82a526 100644
--- a/internal/encoding/wire/wire_test.go
+++ b/internal/encoding/wire/wire_test.go
@@ -136,8 +136,8 @@
wantRaw: dhex("f8ffffff0f"),
consumeOps: ops{consumeTag{wantNum: MaxValidNumber, wantType: VarintType, wantCnt: 5}},
}, {
- appendOps: ops{appendTag{inNum: MaxValidNumber + 1, inType: VarintType}},
- wantRaw: dhex("8080808010"),
+ appendOps: ops{appendVarint{inVal: ((math.MaxInt32+1)<<3 | uint64(VarintType))}},
+ wantRaw: dhex("8080808040"),
consumeOps: ops{consumeTag{wantErr: errFieldNumber}},
}})
}
