jan/cacert-gosigner
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Refactor client into separate files

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Add a main loop, move I/O code into io.go, move configuration into config.go.
Use shared.Decode24BitLength instead of manually decoding block lengths.
Fix response block decoding and checksum validation.
Add constants for commonly used byte values and use these in the signer and
the client.
This commit is contained in:
Jan Dittberner 2020-04-17 19:39:01 +02:00
parent 65855152ce
commit 42d1e6e991
8 changed files with 322 additions and 241 deletions
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11
datastructures/common.go
View file

@ -6,6 +6,15 @@ type Action uint8
const ActionNul = Action(0)
func (a Action) String() string {
switch a {
case ActionNul:
return "NUL"
default:
return "unknown"
}
}
func encode24BitLength(data []byte) []byte {
lengthBytes := make([]byte, 4)
binary.BigEndian.PutUint32(lengthBytes, uint32(len(data)))
@ -13,7 +22,7 @@ func encode24BitLength(data []byte) []byte {
}
// calculate length from 24 bits of data in network byte order
func decode24BitLength(bytes []byte) int {
func Decode24BitLength(bytes []byte) int {
return int(binary.BigEndian.Uint32([]byte{0x0, bytes[0], bytes[1], bytes[2]}))
}

12
datastructures/signerrequest.go
View file

@ -25,19 +25,19 @@ type SignerRequest struct {
const protocolVersion = 1
func SignerRequestFromData(lengthBytes []byte, blockData []byte, checkSum byte) (*SignerRequest, error) {
headerLength := decode24BitLength(blockData[0:3])
headerLength := Decode24BitLength(blockData[0:3])
headerBytes := blockData[3 : 3+headerLength]
contentBytes := blockData[3+headerLength:]
content1Length := decode24BitLength(contentBytes[0:3])
content1Length := Decode24BitLength(contentBytes[0:3])
content1 := string(contentBytes[3 : 3+content1Length])
content2Offset := 3 + content1Length
content2Length := decode24BitLength(contentBytes[content2Offset : content2Offset+3])
content2Length := Decode24BitLength(contentBytes[content2Offset : content2Offset+3])
content2 := string(contentBytes[3+content2Offset : 3+content2Offset+content2Length])
content3Offset := 3 + content2Offset + content2Length
content3Length := decode24BitLength(contentBytes[content3Offset : content3Offset+3])
content3Length := Decode24BitLength(contentBytes[content3Offset : content3Offset+3])
content3 := string(contentBytes[3+content3Offset : 3+content3Offset+content3Length])
calculated := CalculateXorCheckSum([][]byte{lengthBytes, blockData})
@ -79,8 +79,8 @@ func (r SignerRequest) Serialize() []byte {
func NewNulRequest() *SignerRequest {
return &SignerRequest{
Version: protocolVersion,
Action: ActionNul,
Version: protocolVersion,
Action: ActionNul,
Content1: time.Now().UTC().Format("010203042006.05"),
}
}

36
datastructures/signerresponse.go
View file

@ -17,20 +17,26 @@ type SignerResponse struct {
}
func SignerResponseFromData(lengthBytes []byte, blockData []byte, checkSum byte) (*SignerResponse, error) {
headerLength := decode24BitLength(lengthBytes)
headerBytes := blockData[3 : 3+headerLength]
if len(blockData) < 3 {
return nil, errors.New("begin of structure corrupt")
}
contentBytes := blockData[3+headerLength:]
content1Length := decode24BitLength(contentBytes[0:3])
content1 := string(contentBytes[3 : 3+content1Length])
offset := 0
headerLength := Decode24BitLength(blockData[offset : offset+3])
offset += 3
headerBytes := blockData[offset : offset+headerLength]
offset += headerLength
content2Offset := 3 + content1Length
content2Length := decode24BitLength(contentBytes[content2Offset : content2Offset+3])
content2 := string(contentBytes[3+content2Offset : 3+content2Offset+content2Length])
content3Offset := 3 + content2Offset + content2Length
content3Length := decode24BitLength(contentBytes[content3Offset : content3Offset+3])
content3 := string(contentBytes[3+content3Offset : 3+content3Offset+content3Length])
content := make([]string, 3)
for offset < len(blockData) {
dataLength := Decode24BitLength(blockData[offset : offset+3])
if len(blockData)-3 < dataLength {
return nil, errors.New("structure cut off")
}
offset += 3
content = append(content, string(blockData[offset:offset+dataLength]))
offset += dataLength
}
calculated := CalculateXorCheckSum([][]byte{lengthBytes, blockData})
if checkSum != calculated {
@ -42,9 +48,9 @@ func SignerResponseFromData(lengthBytes []byte, blockData []byte, checkSum byte)
Action: Action(headerBytes[1]),
Reserved1: headerBytes[2],
Reserved2: headerBytes[3],
Content1: content1,
Content2: content2,
Content3: content3,
Content1: content[0],
Content2: content[1],
Content3: content[2],
}, nil
}