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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>
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| 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/. | ||
|
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| // Package pcap implements writing packet data to pcap files. | ||
| package pcap | ||
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| import ( | ||
| "encoding/binary" | ||
| "fmt" | ||
| "io" | ||
| "time" | ||
|
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| "github.com/gopacket/gopacket" | ||
| ) | ||
|
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| // 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 | ||
| ) | ||
|
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| // LinkType is the link type for the pcap file. | ||
| type LinkType uint32 | ||
|
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| // LinkType values. | ||
| const ( | ||
| LinkTypeEthernet LinkType = 1 | ||
| LinkTypeRaw LinkType = 101 | ||
| ) | ||
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| // 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} | ||
| } | ||
|
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| // 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 | ||
|
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| binary.LittleEndian.PutUint32(buf[0:4], magicNanoseconds) | ||
| binary.LittleEndian.PutUint16(buf[4:6], versionMajor) | ||
| binary.LittleEndian.PutUint16(buf[6:8], versionMinor) | ||
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| // 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)) | ||
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| _, err := w.w.Write(buf[:]) | ||
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| return err | ||
| } | ||
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| func (w *Writer) writePacketHeader(ci gopacket.CaptureInfo) error { | ||
| t := ci.Timestamp | ||
| if t.IsZero() { | ||
| t = time.Now() | ||
| } | ||
|
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| secs := t.Unix() | ||
| binary.LittleEndian.PutUint32(w.buf[0:4], uint32(secs)) | ||
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| usecs := t.Nanosecond() | ||
| binary.LittleEndian.PutUint32(w.buf[4:8], uint32(usecs)) | ||
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| binary.LittleEndian.PutUint32(w.buf[8:12], uint32(ci.CaptureLength)) | ||
| binary.LittleEndian.PutUint32(w.buf[12:16], uint32(ci.Length)) | ||
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| _, err := w.w.Write(w.buf[:]) | ||
|
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| return err | ||
| } | ||
|
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| // 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)) | ||
| } | ||
|
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| if ci.CaptureLength > ci.Length { | ||
| return fmt.Errorf("invalid capture info %+v: capture length > length", ci) | ||
| } | ||
|
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| if err := w.writePacketHeader(ci); err != nil { | ||
| return fmt.Errorf("error writing packet header: %v", err) | ||
| } | ||
|
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| _, err := w.w.Write(data) | ||
|
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| return err | ||
| } |