grpc: fix receiving empty messages when compression is enabled and maxReceiveMessageSize is maxInt64 #7753 #7918
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arjan-bal
added
Area: RPC Features
Codecov ReportAll modified and coverable lines are covered by tests ✅
Additional details and impacted files@@ Coverage Diff @@
## master #7918 +/- ##
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+ Coverage 81.84% 82.12% +0.27%
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Files 377 378 +1
Lines 38120 38269 +149
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+ Hits 31201 31428 +227
+ Misses 5603 5542 -61
+ Partials 1316 1299 -17
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rpc_util.go
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| if err != nil { | ||
| out.Free() | ||
| return nil, 0, err | ||
| } | ||
| if err = checkReceiveMessageOverflow(int64(out.Len()), int64(maxReceiveMessageSize), dcReader); err != nil { | ||
| return nil, out.Len() + 1, err |
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Adding 1 to out.Len() can result in an overflow on 32 bit systems. The following part of the function seems strange to me:
Optionally, if data will be over maxReceiveMessageSize, just return the size
I suggest making the following change to avoid this:
- Declare a global error for indicating that the max receive size is exceeded:
var errMaxMessageSizeExceeded = errors.New("max message size exceeded")- When the check here fails,
nil, 0, errMaxMessageSizeExceeded. Update the godoc to mention the same. - In the caller, i.e. recvAndDecompress, instead of checking
if size > maxReceiveMessageSize, checkif err == errMaxMessageSizeExceeded. Also update the error message to not mention the actual size, because we didn't read the entire message anyways:grpc: received message after decompression larger than max %d.
This ensures we're using the returned error to indicate the failure instead of relying on special values of the bytes read count.
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Please let the reviewer resolve comments.
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We should not attempt to add out.Len() + 1, instead return errMaxMessageSizeExceeded to signal the same.
rpc_util.go
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| // If additional data is read, or an error other than `io.EOF` is encountered, the function | ||
| // returns an error indicating that the message size has exceeded the permissible limit. | ||
| func checkReceiveMessageOverflow(readBytes, maxReceiveMessageSize int64, dcReader io.Reader) error { | ||
| if readBytes == maxReceiveMessageSize { |
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You can invert this check and returns early to reduce indentation.
if readBytes < maxReceiveMessageSize {
return nil
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I fixed all the comments.
rpc_util.go
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| if err != nil { | ||
| out.Free() | ||
| return nil, 0, err | ||
| } | ||
| if err = checkReceiveMessageOverflow(int64(out.Len()), int64(maxReceiveMessageSize), dcReader); err != nil { | ||
| return nil, out.Len() + 1, err |
There was a problem hiding this comment.
Please let the reviewer resolve comments.
rpc_util.go
Outdated
| if err != nil { | ||
| out.Free() | ||
| return nil, 0, err | ||
| } | ||
| if err = checkReceiveMessageOverflow(int64(out.Len()), int64(maxReceiveMessageSize), dcReader); err != nil { | ||
| return nil, out.Len() + 1, err |
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We should not attempt to add out.Len() + 1, instead return errMaxMessageSizeExceeded to signal the same.
Fixes #4552
RELEASE NOTES: