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@@ -0,0 +1,66 @@
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+// Package socks contains protocol definition and io lib for SOCKS5 protocol
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+package socks
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+
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+import (
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+ "fmt"
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+ "io"
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+)
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+
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+const (
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+ socksVersion = uint8(5)
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+)
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+
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+// Authentication request header of Socks5 protocol
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+type Socks5AuthenticationRequest struct {
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+ version byte
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+ authMethods [256]byte
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+}
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+
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+func ReadAuthentication(reader io.Reader) (auth Socks5AuthenticationRequest, err error) {
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+ buffer := make([]byte, 2)
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+ nBytes, err := reader.Read(buffer)
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+ if err != nil {
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+ return
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+ }
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+ if nBytes < 2 {
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+ err = fmt.Errorf("Expected 2 bytes read, but actaully %d bytes read", nBytes)
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+ return
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+ }
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+
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+ auth.version = buffer[0]
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+ if auth.version != socksVersion {
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+ err = fmt.Errorf("Unknown SOCKS version %d", auth.version)
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+ return
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+ }
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+
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+ nMethods := buffer[1]
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+ if nMethods <= 0 {
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+ err = fmt.Errorf("Zero length of authentication methods")
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+ return
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+ }
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+
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+ buffer = make([]byte, nMethods)
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+ nBytes, err = reader.Read(buffer)
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+ copy(auth.authMethods[:nBytes], buffer)
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+ return
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+}
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+
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+type Socks5AuthenticationResponse struct {
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+ version byte
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+ authMethod byte
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+}
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+
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+func (r *Socks5AuthenticationResponse) ToBytes() []byte {
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+ buffer := make([]byte, 2 /* size of Socks5AuthenticationResponse */)
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+ buffer[0] = r.version
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+ buffer[1] = r.authMethod
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+ return buffer
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+}
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+
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+func WriteAuthentication(writer io.Writer, response Socks5AuthenticationResponse) error {
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+ _, err := writer.Write(response.ToBytes())
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+ if err != nil {
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+ return err
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+ }
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+ return nil
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+}
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