Initial commit

This commit is contained in:
Alex D. 2024-06-14 21:26:46 +00:00
commit 444b8b2f2f
Signed by: caskd
GPG Key ID: F92BA85F61F4C173
7 changed files with 323 additions and 0 deletions

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.gitignore vendored Normal file
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net-predictable
go.sum

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LICENSE.md Normal file
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Copyright (c) 2024 Alex Denes
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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go.mod Normal file
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module git.redxen.eu/caskd/net-predictable
go 1.22.3
require github.com/vishvananda/netlink v1.1.0
require (
github.com/vishvananda/netns v0.0.0-20191106174202-0a2b9b5464df // indirect
golang.org/x/sys v0.0.0-20190606203320-7fc4e5ec1444 // indirect
)

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main.go Normal file
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package main
import (
"flag"
"log"
"os"
"github.com/vishvananda/netlink"
)
func main() {
var (
err error
mainlog = log.New(os.Stderr, "net-predictable: ", log.Lmsgprefix|log.Ltime)
ifnparam string
)
flag.StringVar(&ifnparam, "ifname", "", "Interface name to rename")
flag.Parse()
mainlog.Printf("%#v", os.Environ())
// Probe different methods to get interface name
var ifname = ""
for _, v := range []string{
ifnparam,
os.Getenv("INTERFACE"),
os.Getenv("MDEV"),
os.Getenv("IFNAME"),
} {
if v != "" {
ifname = v
break
}
}
if ifname == "" {
mainlog.Println("No interface name provided")
return
}
var cif iface
if cif, err = New(ifname); err != nil {
mainlog.Println("Failed creating interface data:", err)
return
}
var should bool
if should, err = cif.shouldRun(); err != nil {
mainlog.Println(err)
}
if !should {
mainlog.Println("Interface is already renamed, exiting")
return
}
var nln string
if nln, err = cif.Process(); err != nil {
mainlog.Println("Failed to process interface:", err)
return
}
if ifname == nln {
mainlog.Println("Interface already named correctly")
return
}
mainlog.Printf("Renaming %s to %s\n", ifname, nln)
var l netlink.Link
if l, err = netlink.LinkByName(ifname); err != nil {
mainlog.Fatalln("Interface", ifname, "disappeared before it could be renamed")
}
if err = netlink.LinkSetName(l, nln); err != nil {
mainlog.Fatalf("Could not rename interface %s: %s\n", ifname, err)
}
}

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misc.go Normal file
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package main
import (
"errors"
"fmt"
"io"
"os"
"path/filepath"
"strconv"
"strings"
)
const (
PathProcPCI = iota
PathProcUSB
)
var (
ErrInvalidPCIFormat = errors.New("Invalid PCI address format")
ErrInvalidUSBFormat = errors.New("Invalid USB address format")
)
var SYSFS = "/sys"
// Sourced from include/uapi/linux/netdevice.h
// as of v6.8
const (
NET_NAME_UNKNOWN = 0 /* unknown origin (not exposed to userspace) */
NET_NAME_ENUM = 1 /* enumerated by kernel */
NET_NAME_PREDICTABLE = 2 /* predictably named by the kernel */
NET_NAME_USER = 3 /* provided by user-space */
NET_NAME_RENAMED = 4 /* renamed by user-space */
)
const (
ClassEthernet = iota
ClassWireless
)
type iface struct {
class int
orig string
path []string
pci, usb string
}
func (i iface) String() string {
var pfx string
switch i.class {
case ClassEthernet:
pfx = "en"
case ClassWireless:
pfx = "wl"
}
return fmt.Sprintf("%s%s%s", pfx, i.pci, i.usb)
}
func New(ifname string) (i iface, err error) {
i.orig = ifname
spath := strings.Join([]string{SYSFS, "class/net", i.orig, "device"}, "/")
var real string
if real, err = filepath.EvalSymlinks(spath); err != nil {
if errors.Is(err, os.ErrNotExist) {
err = fmt.Errorf("Interface %s isn't a device", i.orig)
return
}
err = fmt.Errorf("Failed to resolve symlink to device: %w", err)
return
}
var devpath string
var ok bool
sysdev := strings.Join([]string{SYSFS, "devices/"}, "/")
if devpath, ok = strings.CutPrefix(real, sysdev); !ok {
err = fmt.Errorf("Symlink doesn't point to %s\n", sysdev)
return
}
i.path = strings.Split(devpath, "/")
switch ifname[0] {
case 'e':
i.class = ClassEthernet
case 'w':
i.class = ClassWireless
}
return
}
func (i iface) shouldRun() (should bool, err error) {
ifname_assign_type := strings.Join([]string{SYSFS, "class/net", i.orig, "name_assign_type"}, "/")
should = true
var (
file *os.File
contents []byte
)
if file, err = os.Open(ifname_assign_type); err != nil {
err = fmt.Errorf("Failed to open interface rename property: %w", err)
} else {
if contents, err = io.ReadAll(file); err != nil {
err = fmt.Errorf("Failed to read interface rename property: %w", err)
} else {
file.Close()
num, _ := strings.CutSuffix(string(contents), "\n")
var res int
if res, err = strconv.Atoi(num); err != nil {
err = fmt.Errorf("Failed to interpret interface rename property as number: %w", err)
} else {
if res != NET_NAME_ENUM {
should = false
return
}
}
}
}
return
}
func (i iface) Process() (nif string, err error) {
var (
procmode int
)
for _, v := range i.path {
if strings.HasPrefix(v, "pci") {
procmode = PathProcPCI
continue
} else if strings.HasPrefix(v, "usb") {
procmode = PathProcUSB
continue
}
switch procmode {
case PathProcPCI:
{
var hold string
if hold, err = ProcPCI(v); err != nil {
continue
}
i.pci = hold
}
case PathProcUSB:
{
var hold string
if hold, err = ProcUSB(v); err != nil {
continue
}
i.usb = hold
}
}
}
nif = i.String()
// It can error but as long as we get a identifier along the path it's okay
if i.pci != "" {
err = nil
}
return
}

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pci.go Normal file
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package main
import (
"fmt"
)
func ProcPCI(devpath string) (segment string, err error) {
var (
domain, bus, device, function int
)
if _, err = fmt.Sscanf(devpath, "%x:%x:%x.%x", &domain, &bus, &device, &function); err != nil {
err = ErrInvalidPCIFormat
return
}
segment = fmt.Sprintf("p%ds%df%d", bus, device, function)
return
}

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usb.go Normal file
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package main
import (
"fmt"
"strings"
)
func ProcUSB(devpath string) (segment string, err error) {
var (
bus, conf, iface int
port_path []int
work string
)
res := strings.Split(devpath, ":")
if len(res) != 2 {
err = ErrInvalidUSBFormat
return
}
// Bus and ports
if _, err = fmt.Sscanf(res[0], "%d-%s", &bus, &work); err != nil {
err = ErrInvalidUSBFormat
return
}
for _, v := range strings.Split(work, ".") {
var cp int
if _, err = fmt.Sscanf(v, "%d", &cp); err != nil {
err = ErrInvalidUSBFormat
return
}
port_path = append(port_path, cp)
}
// Configuration and interface
if _, err = fmt.Sscanf(res[1], "%d.%d", &conf, &iface); err != nil {
err = ErrInvalidUSBFormat
return
}
var b strings.Builder
for _, v := range port_path {
b.WriteString(fmt.Sprintf("u%d", v))
}
b.WriteString(fmt.Sprintf("i%d", iface))
segment = b.String()
return
}