func getIPHeaderLayerV4()

in internal/ip/ip_darwin.go [45:67]

• 20 lines of code
• 1 McCabe index (conditional complexity)

func getIPHeaderLayerV4(tos DSCPValue, tcpLen uint16, srcIP net.IP, dstIP net.IP) *layers.IPv4 {
	header := &layers.IPv4{
		Version:    4, // IP Version 4
		TOS:        uint8(tos),
		IHL:        5,           // IHL: 20 bytes
		Length:     tcpLen + 20, // Total IP packet length
		FragOffset: 0,           // No fragmentation
		Flags:      0,           // Flags for fragmentation
		TTL:        defines.IPTTL,
		Protocol:   layers.IPProtocolTCP,
		Checksum:   0, // Computed at serialization time
		SrcIP:      srcIP,
		DstIP:      dstIP,
	}

	// Manually convert Length and FragOffset to host-byte order for Darwin
	header.Length = (header.Length << 8) | (header.Length >> 8)
	nf := layers.IPv4Flag(header.FragOffset & 0xE0)
	header.FragOffset = (header.FragOffset & 0x1F << 8) | (header.FragOffset>>8 | uint16(header.Flags))
	header.Flags = nf

	return header
}