-
Notifications
You must be signed in to change notification settings - Fork 544
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
refactor: update packet capture to use 'afpacket' interface
First of all, this interface is way more performant than `pcap` interface. It is Linux-specific, but we don't care in Talos Linux :) Second, this drop dependency of `machined` on `gopacket/layers` package, which has huge issues with memory allocations and startup time. This cuts around 20MiB of process RSS for all Talos processes. (`talosctl` still requires this `gopacket/layers` library for decoding packets). Fixes #7880 Signed-off-by: Andrey Smirnov <andrey.smirnov@siderolabs.com>
- Loading branch information
Showing
2 changed files
with
140 additions
and
28 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,109 @@ | ||
| // This Source Code Form is subject to the terms of the Mozilla Public | ||
| // License, v. 2.0. If a copy of the MPL was not distributed with this | ||
| // file, You can obtain one at http://mozilla.org/MPL/2.0/. | ||
|
|
||
| // Package pcap implements writing packet data to pcap files. | ||
| package pcap | ||
|
|
||
| import ( | ||
| "encoding/binary" | ||
| "fmt" | ||
| "io" | ||
| "time" | ||
|
|
||
| "github.com/gopacket/gopacket" | ||
| ) | ||
|
|
||
| // Writer wraps an underlying io.Writer to write packet data in PCAP | ||
| // format. See http://wiki.wireshark.org/Development/LibpcapFileFormat | ||
| // for information on the file format. | ||
| // | ||
| // For those that care, we currently write v2.4 files with nanosecond | ||
| // or microsecond timestamp resolution and little-endian encoding. | ||
| type Writer struct { | ||
| w io.Writer | ||
| buf [16]byte | ||
| } | ||
|
|
||
| const ( | ||
| magicNanoseconds = 0xA1B23C4D | ||
| versionMajor = 2 | ||
| versionMinor = 4 | ||
| ) | ||
|
|
||
| // LinkType is the link type for the pcap file. | ||
| type LinkType uint32 | ||
|
|
||
| // LinkType values. | ||
| const ( | ||
| LinkTypeEthernet LinkType = 1 | ||
| LinkTypeRaw LinkType = 101 | ||
| ) | ||
|
|
||
| // NewWriter returns a new writer object. | ||
| // | ||
| // If this is a new empty writer (as opposed to | ||
| // an append), you must call WriteFileHeader before WritePacket. Packet | ||
| // timestamps are written with nanosecond precision. | ||
| func NewWriter(w io.Writer) *Writer { | ||
| return &Writer{w: w} | ||
| } | ||
|
|
||
| // WriteFileHeader writes a file header out to the writer. | ||
| // This must be called exactly once per output. | ||
| func (w *Writer) WriteFileHeader(snaplen uint32, linktype LinkType) error { | ||
| var buf [24]byte | ||
|
|
||
| binary.LittleEndian.PutUint32(buf[0:4], magicNanoseconds) | ||
| binary.LittleEndian.PutUint16(buf[4:6], versionMajor) | ||
| binary.LittleEndian.PutUint16(buf[6:8], versionMinor) | ||
|
|
||
| // bytes 8:12 stay 0 (timezone = UTC) | ||
| // bytes 12:16 stay 0 (sigfigs is always set to zero, according to | ||
| // http://wiki.wireshark.org/Development/LibpcapFileFormat | ||
| binary.LittleEndian.PutUint32(buf[16:20], snaplen) | ||
| binary.LittleEndian.PutUint32(buf[20:24], uint32(linktype)) | ||
|
|
||
| _, err := w.w.Write(buf[:]) | ||
|
|
||
| return err | ||
| } | ||
|
|
||
| func (w *Writer) writePacketHeader(ci gopacket.CaptureInfo) error { | ||
| t := ci.Timestamp | ||
| if t.IsZero() { | ||
| t = time.Now() | ||
| } | ||
|
|
||
| secs := t.Unix() | ||
| binary.LittleEndian.PutUint32(w.buf[0:4], uint32(secs)) | ||
|
|
||
| usecs := t.Nanosecond() | ||
| binary.LittleEndian.PutUint32(w.buf[4:8], uint32(usecs)) | ||
|
|
||
| binary.LittleEndian.PutUint32(w.buf[8:12], uint32(ci.CaptureLength)) | ||
| binary.LittleEndian.PutUint32(w.buf[12:16], uint32(ci.Length)) | ||
|
|
||
| _, err := w.w.Write(w.buf[:]) | ||
|
|
||
| return err | ||
| } | ||
|
|
||
| // WritePacket writes the given packet data out to the file. | ||
| func (w *Writer) WritePacket(ci gopacket.CaptureInfo, data []byte) error { | ||
| if ci.CaptureLength != len(data) { | ||
| return fmt.Errorf("capture length %d does not match data length %d", ci.CaptureLength, len(data)) | ||
| } | ||
|
|
||
| if ci.CaptureLength > ci.Length { | ||
| return fmt.Errorf("invalid capture info %+v: capture length > length", ci) | ||
| } | ||
|
|
||
| if err := w.writePacketHeader(ci); err != nil { | ||
| return fmt.Errorf("error writing packet header: %v", err) | ||
| } | ||
|
|
||
| _, err := w.w.Write(data) | ||
|
|
||
| return err | ||
| } |