GODRIVER-3303 Remove redundant code; Add test cases. (#1753)

Co-authored-by: Kobrin Ilay <ilayko3110@yandex.ru>

mongo/integration/mtest/wiremessage_helpers.go

@@ -49,16 +49,11 @@ func parseOpCompressed(wm []byte) (wiremessage.OpCode, []byte, error) {
  return originalOpcode, nil, errors.New("failed to read uncompressed size")
  }
 
- compressorID, wm, ok := wiremessage.ReadCompressedCompressorID(wm)
+ compressorID, compressedMsg, ok := wiremessage.ReadCompressedCompressorID(wm)
  if !ok {
  return originalOpcode, nil, errors.New("failed to read compressor ID")
  }
 
- compressedMsg, _, ok := wiremessage.ReadCompressedCompressedMessage(wm, int32(len(wm)))
- if !ok {
- return originalOpcode, nil, errors.New("failed to read compressed message")
- }
-
  opts := driver.CompressionOpts{
  Compressor: compressorID,
  UncompressedSize: uncompressedSize,

x/mongo/driver/operation.go

@@ -1199,18 +1199,12 @@ func (Operation) decompressWireMessage(wm []byte) (wiremessage.OpCode, []byte, e
  if !ok {
  return 0, nil, errors.New("malformed OP_COMPRESSED: missing compressor ID")
  }
- compressedSize := len(wm) - 9 // original opcode (4) + uncompressed size (4) + compressor ID (1)
- // return the original wiremessage
- msg, _, ok := wiremessage.ReadCompressedCompressedMessage(rem, int32(compressedSize))
- if !ok {
- return 0, nil, errors.New("malformed OP_COMPRESSED: insufficient bytes for compressed wiremessage")
- }
 
  opts := CompressionOpts{
  Compressor: compressorID,
  UncompressedSize: uncompressedSize,
  }
- uncompressed, err := DecompressPayload(msg, opts)
+ uncompressed, err := DecompressPayload(rem, opts)
  if err != nil {
  return 0, nil, err
  }

x/mongo/driver/wiremessage/wiremessage.go

@@ -381,16 +381,9 @@ func ReadMsgSectionSingleDocument(src []byte) (doc bsoncore.Document, rem []byte
 // ReadMsgSectionDocumentSequence reads an identifier and document sequence from src and returns the document sequence
 // data parsed into a slice of BSON documents.
 func ReadMsgSectionDocumentSequence(src []byte) (identifier string, docs []bsoncore.Document, rem []byte, ok bool) {
- length, rem, ok := readi32(src)
- if !ok || int(length) > len(src) || length-4 < 0 {
- return "", nil, rem, false
- }
-
- rem, ret := rem[:length-4], rem[length-4:] // reslice so we can just iterate a loop later
-
- identifier, rem, ok = readcstring(rem)
+ identifier, rem, ret, ok := ReadMsgSectionRawDocumentSequence(src)
  if !ok {
- return "", nil, rem, false
+ return "", nil, src, false
  }
 
  docs = make([]bsoncore.Document, 0)
@@ -403,7 +396,7 @@ func ReadMsgSectionDocumentSequence(src []byte) (identifier string, docs []bsonc
  docs = append(docs, doc)
  }
  if len(rem) > 0 {
- return "", nil, append(rem, ret...), false
+ return "", nil, src, false
  }
 
  return identifier, docs, ret, true
@@ -414,7 +407,7 @@ func ReadMsgSectionDocumentSequence(src []byte) (identifier string, docs []bsonc
 func ReadMsgSectionRawDocumentSequence(src []byte) (identifier string, data []byte, rem []byte, ok bool) {
  length, rem, ok := readi32(src)
  if !ok || int(length) > len(src) || length-4 < 0 {
- return "", nil, rem, false
+ return "", nil, src, false
  }
 
  // After these assignments, rem will be the data containing the identifier string + the document sequence bytes and
@@ -423,7 +416,7 @@ func ReadMsgSectionRawDocumentSequence(src []byte) (identifier string, data []by
 
  identifier, rem, ok = readcstring(rem)
  if !ok {
- return "", nil, rem, false
+ return "", nil, src, false
  }
 
  return identifier, rem, rest, true
@@ -546,14 +539,6 @@ func ReadCompressedCompressorID(src []byte) (id CompressorID, rem []byte, ok boo
  return CompressorID(src[0]), src[1:], true
 }
 
-// ReadCompressedCompressedMessage reads the compressed wiremessage to dst.
-func ReadCompressedCompressedMessage(src []byte, length int32) (msg []byte, rem []byte, ok bool) {
- if len(src) < int(length) || length < 0 {
- return nil, src, false
- }
- return src[:length], src[length:], true
-}
-
 // ReadKillCursorsZero reads the zero field from src.
 func ReadKillCursorsZero(src []byte) (zero int32, rem []byte, ok bool) {
  return readi32(src)

x/mongo/driver/wiremessage/wiremessage_test.go

@@ -175,6 +175,22 @@ func TestReadMsgSectionDocumentSequence(t *testing.T) {
  wantRem: []byte{0, 1},
  wantOK: false,
  },
+ {
+ desc: "incorrect size",
+ src: []byte{3, 0, 0},
+ wantIdentifier: "",
+ wantDocs: nil,
+ wantRem: []byte{3, 0, 0},
+ wantOK: false,
+ },
+ {
+ desc: "insufficient size",
+ src: []byte{4, 0, 0},
+ wantIdentifier: "",
+ wantDocs: nil,
+ wantRem: []byte{4, 0, 0},
+ wantOK: false,
+ },
  {
  desc: "nil",
  src: nil,