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all: imp code & test, log changes

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This commit is contained in:
Eugene Burkov
2025-03-06 15:15:06 +03:00
parent 0c72cde4c3
commit 74640fb06c
4 changed files with 80 additions and 53 deletions
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31
internal/dhcpd/routeradv.go
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@@ -4,6 +4,7 @@ import (
"encoding/binary"
"fmt"
"net"
"slices"
"sync/atomic"
"time"
@@ -14,6 +15,9 @@ import (
"golang.org/x/net/ipv6"
)
// raCtx is a context for the Router Advertisement logic.
//
// TODO(e.burkov): !! Improve docs
type raCtx struct {
raAllowSLAAC bool // send RA packets with MO flags
raSLAACOnly bool // send RA packets without MO flags
@@ -50,10 +54,8 @@ func hwAddrToLinkLayerAddr(hwa net.HardwareAddr) (lla []byte, err error) {
return nil, err
}
lla = make([]byte, len(hwa))
copy(lla, hwa)
return lla, nil
// TODO(e.burkov): Check if it's safe to use the original slice.
return slices.Clone(hwa), nil
}
// Create an ICMPv6.RouterAdvertisement packet with all necessary options.
@@ -94,21 +96,19 @@ func hwAddrToLinkLayerAddr(hwa net.HardwareAddr) (lla []byte, err error) {
//
// TODO(a.garipov): Replace with an existing implementation from a dependency.
func createICMPv6RAPacket(params icmpv6RA) (data []byte, err error) {
var lla []byte
lla, err = hwAddrToLinkLayerAddr(params.sourceLinkLayerAddress)
lla, err := hwAddrToLinkLayerAddr(params.sourceLinkLayerAddress)
if err != nil {
return nil, fmt.Errorf("converting source link layer address: %w", err)
}
// Calculate length of source link layer address section
// This is based on calculation from radvd's add_ra_option_sllao function
sllao_bytes := len(lla) + 2
sllao_len := (sllao_bytes + 7) / 8
sllao_pad_bytes := sllao_len * 8 - sllao_bytes
// Calculate length of the source link-layer address option.
srcLLAOptLen := len(lla) + 2
srcLLAOptLenValue := (srcLLAOptLen + 7) / 8
srcLLAPadLen := srcLLAOptLenValue*8 - srcLLAOptLen
// TODO(a.garipov): Don't use a magic constant here. Refactor the code
// and make all constants named instead of all those comments..
data = make([]byte, 80+sllao_bytes+sllao_pad_bytes)
data = make([]byte, 80+srcLLAOptLen+srcLLAPadLen)
i := 0
// ICMPv6:
@@ -172,12 +172,11 @@ func createICMPv6RAPacket(params icmpv6RA) (data []byte, err error) {
// Option=Source link-layer address:
data[i] = 1 // Type
data[i+1] = byte(sllao_len) // Length
data[i] = 1 // Type
data[i+1] = byte(srcLLAOptLenValue) // Length
i += 2
copy(data[i:], lla) // Link-Layer Address[8/24]
i += len(lla) + sllao_pad_bytes
i += len(lla) + srcLLAPadLen
// Option=Recursive DNS Server: