github.com/geniusesgroup/libgo@v0.0.0-20220713101832-828057a9d3d4/gp/packet.go (about)

     1  /* For license and copyright information please see LEGAL file in repository */
     2  
     3  package gp
     4  
     5  import "../protocol"
     6  
     7  const (
     8  	// MinPacketLen is minimum packet length of GP packet
     9  	// 320bit header + 128bit min payload
    10  	MinPacketLen = 56
    11  )
    12  
    13  type packet []byte
    14  
    15  // CheckPacket will check packet for any bad situation!
    16  // Always check packet before use any other packet methods otherwise panic occur!
    17  func CheckPacket(p []byte) protocol.Error {
    18  	if len(p) < MinPacketLen {
    19  		return ErrPacketTooShort
    20  	}
    21  	return nil
    22  }
    23  
    24  // GetDestinationAddr returns full destination GP address.
    25  func GetDestinationAddr(p []byte) (addr Addr) {
    26  	copy(addr[:], p[:])
    27  	return
    28  }
    29  
    30  // GetSourceAddr returns full source GP address.
    31  func GetSourceAddr(p []byte) (addr Addr) {
    32  	copy(addr[:], p[16:])
    33  	return
    34  }
    35  
    36  // GetPacketNumber returns packet number
    37  func GetPacketNumber(p []byte) uint64 {
    38  	return uint64(p[32]) | uint64(p[33])<<8 | uint64(p[34]<<16) | uint64(p[35])<<24 | uint64(p[36]<<32) | uint64(p[37])<<40 | uint64(p[38]<<48) | uint64(p[39])<<56
    39  }
    40  
    41  // GetPayload returns payload that means all data after packetNumber
    42  func GetPayload(p []byte) []byte {
    43  	return p[40:]
    44  }