65 lines
1.9 KiB
Go
65 lines
1.9 KiB
Go
package reverse
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import (
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"net"
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"net/netip"
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"github.com/indra-labs/indra"
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log2 "github.com/indra-labs/indra/pkg/proc/log"
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"github.com/indra-labs/indra/pkg/types"
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"github.com/indra-labs/indra/pkg/util/slice"
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"github.com/indra-labs/indra/pkg/wire/magicbytes"
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)
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const (
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MagicString = "rv"
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Len = magicbytes.Len + 1 + net.IPv6len + 2
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)
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var (
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log = log2.GetLogger(indra.PathBase)
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check = log.E.Chk
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Magic = slice.Bytes(MagicString)
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_ types.Onion = &OnionSkin{}
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)
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// OnionSkin is reply messages, distinct from forward.OnionSkin messages in that
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// the header encryption uses a different secret than the payload. The magic
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// bytes signal this to the relay that receives this, which then looks up the
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// PayloadHey matching the To address in the message header. And lastly, each
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// step the relay budges up it's message to the front of the packet and puts
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// csprng random bytes into the remainder to the same length.
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type OnionSkin struct {
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// AddrPort is the address of the next relay in the return leg of a
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// circuit.
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*netip.AddrPort
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types.Onion
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}
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func (x *OnionSkin) Inner() types.Onion { return x.Onion }
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func (x *OnionSkin) Insert(o types.Onion) { x.Onion = o }
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func (x *OnionSkin) Len() int { return Len + x.Onion.Len() }
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func (x *OnionSkin) Encode(b slice.Bytes, c *slice.Cursor) {
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copy(b[*c:c.Inc(magicbytes.Len)], Magic)
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var ap []byte
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var e error
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if ap, e = x.AddrPort.MarshalBinary(); check(e) {
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return
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}
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b[*c] = byte(len(ap))
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copy(b[c.Inc(1):c.Inc(Len-magicbytes.Len-1)], ap)
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x.Onion.Encode(b, c)
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}
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func (x *OnionSkin) Decode(b slice.Bytes, c *slice.Cursor) (e error) {
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if len(b[*c:]) < Len-magicbytes.Len {
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return magicbytes.TooShort(len(b[*c:]), Len-magicbytes.Len, string(Magic))
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}
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apLen := b[*c]
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apBytes := b[c.Inc(1):c.Inc(Len-magicbytes.Len-1)]
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x.AddrPort = &netip.AddrPort{}
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if e = x.AddrPort.UnmarshalBinary(apBytes[:apLen]); check(e) {
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return
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}
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return
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}
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