mirror of
https://github.com/cwinfo/yggdrasil-go.git
synced 2024-12-03 07:21:37 +00:00
121 lines
3.3 KiB
Go
121 lines
3.3 KiB
Go
package yggdrasil
|
|
|
|
type address [16]byte // IPv6 address within the network
|
|
type subnet [8]byte // It's a /64
|
|
|
|
var address_prefix = [...]byte{0xfd} // For node addresses + local subnets
|
|
|
|
func (a *address) isValid() bool {
|
|
for idx := range address_prefix {
|
|
if (*a)[idx] != address_prefix[idx] {
|
|
return false
|
|
}
|
|
}
|
|
return (*a)[len(address_prefix)]&0x80 == 0
|
|
}
|
|
|
|
func (s *subnet) isValid() bool {
|
|
for idx := range address_prefix {
|
|
if (*s)[idx] != address_prefix[idx] {
|
|
return false
|
|
}
|
|
}
|
|
return (*s)[len(address_prefix)]&0x80 != 0
|
|
}
|
|
|
|
func address_addrForNodeID(nid *NodeID) *address {
|
|
// 128 bit address
|
|
// Begins with prefix
|
|
// Next bit is a 0
|
|
// Next 7 bits, interpreted as a uint, are # of leading 1s in the NodeID
|
|
// Leading 1s and first leading 0 of the NodeID are truncated off
|
|
// The rest is appended to the IPv6 address (truncated to 128 bits total)
|
|
var addr address
|
|
var temp []byte
|
|
done := false
|
|
ones := byte(0)
|
|
bits := byte(0)
|
|
nBits := 0
|
|
for idx := 0; idx < 8*len(nid); idx++ {
|
|
bit := (nid[idx/8] & (0x80 >> byte(idx%8))) >> byte(7-(idx%8))
|
|
if !done && bit != 0 {
|
|
ones++
|
|
continue
|
|
}
|
|
if !done && bit == 0 {
|
|
done = true
|
|
continue // FIXME this assumes that ones <= 127
|
|
}
|
|
bits = (bits << 1) | bit
|
|
nBits++
|
|
if nBits == 8 {
|
|
nBits = 0
|
|
temp = append(temp, bits)
|
|
}
|
|
}
|
|
copy(addr[:], address_prefix[:])
|
|
addr[len(address_prefix)] = ones & 0x7f
|
|
copy(addr[len(address_prefix)+1:], temp)
|
|
return &addr
|
|
}
|
|
|
|
func address_subnetForNodeID(nid *NodeID) *subnet {
|
|
// Exactly as the address version, with two exceptions:
|
|
// 1) The first bit after the fixed prefix is a 1 instead of a 0
|
|
// 2) It's truncated to a subnet prefix length instead of 128 bits
|
|
addr := *address_addrForNodeID(nid)
|
|
var snet subnet
|
|
copy(snet[:], addr[:])
|
|
snet[len(address_prefix)] |= 0x80
|
|
return &snet
|
|
}
|
|
|
|
func (a *address) getNodeIDandMask() (*NodeID, *NodeID) {
|
|
// Mask is a bitmask to mark the bits visible from the address
|
|
// This means truncated leading 1s, first leading 0, and visible part of addr
|
|
var nid NodeID
|
|
var mask NodeID
|
|
ones := int(a[len(address_prefix)] & 0x7f)
|
|
for idx := 0; idx < ones; idx++ {
|
|
nid[idx/8] |= 0x80 >> byte(idx%8)
|
|
}
|
|
nidOffset := ones + 1
|
|
addrOffset := 8*len(address_prefix) + 8
|
|
for idx := addrOffset; idx < 8*len(a); idx++ {
|
|
bits := a[idx/8] & (0x80 >> byte(idx%8))
|
|
bits <<= byte(idx % 8)
|
|
nidIdx := nidOffset + (idx - addrOffset)
|
|
bits >>= byte(nidIdx % 8)
|
|
nid[nidIdx/8] |= bits
|
|
}
|
|
maxMask := 8*(len(a)-len(address_prefix)-1) + ones + 1
|
|
for idx := 0; idx < maxMask; idx++ {
|
|
mask[idx/8] |= 0x80 >> byte(idx%8)
|
|
}
|
|
return &nid, &mask
|
|
}
|
|
|
|
func (s *subnet) getNodeIDandMask() (*NodeID, *NodeID) {
|
|
// As with the address version, but visible parts of the subnet prefix instead
|
|
var nid NodeID
|
|
var mask NodeID
|
|
ones := int(s[len(address_prefix)] & 0x7f)
|
|
for idx := 0; idx < ones; idx++ {
|
|
nid[idx/8] |= 0x80 >> byte(idx%8)
|
|
}
|
|
nidOffset := ones + 1
|
|
addrOffset := 8*len(address_prefix) + 8
|
|
for idx := addrOffset; idx < 8*len(s); idx++ {
|
|
bits := s[idx/8] & (0x80 >> byte(idx%8))
|
|
bits <<= byte(idx % 8)
|
|
nidIdx := nidOffset + (idx - addrOffset)
|
|
bits >>= byte(nidIdx % 8)
|
|
nid[nidIdx/8] |= bits
|
|
}
|
|
maxMask := 8*(len(s)-len(address_prefix)-1) + ones + 1
|
|
for idx := 0; idx < maxMask; idx++ {
|
|
mask[idx/8] |= 0x80 >> byte(idx%8)
|
|
}
|
|
return &nid, &mask
|
|
}
|