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d5ab63cfb9
This is how collection of serial could look on Linux (and this lib also supports Windows). Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>
83 lines
2.2 KiB
Go
83 lines
2.2 KiB
Go
//go:build linux
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package posture
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import (
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"errors"
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"fmt"
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"strings"
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"github.com/digitalocean/go-smbios"
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)
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// GetByte retrieves a 8-bit unsigned integer at the given offset.
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func GetByte(s *smbios.Structure, offset int) uint8 {
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// the `Formatted` byte slice is missing the first 4 bytes of the structure that are stripped out as header info.
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// so we need to subtract 4 from the offset mentioned in the SMBIOS documentation to get the right value.
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index := offset - 4
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if index >= len(s.Formatted) {
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return 0
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}
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return s.Formatted[index]
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}
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// GetStringOrEmpty retrieves a string at the given offset.
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// Returns an empty string if no string was present.
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func GetStringOrEmpty(s *smbios.Structure, offset int) (string, error) {
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index := GetByte(s, offset)
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if index == 0 || int(index) > len(s.Strings) {
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return errors.New("offset does not exist in smbios structure")
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}
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str := s.Strings[index-1]
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trimmed := strings.TrimSpace(str)
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// Convert to lowercase to address multiple formats:
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// - "To Be Filled By O.E.M."
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// - "To be filled by O.E.M."
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if strings.ToLower(trimmed) == "to be filled by o.e.m." {
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return errors.New("data is not provided by O.E.M.")
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}
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return trimmed
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}
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// System Information (Type 1) structure
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// https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.1.1.pdf
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// Page 34
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const (
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sysInfoHeaderType = 1
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serialNumberOffset = 0x07
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)
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func getSerialNumber() (string, error) {
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// Find SMBIOS data in operating system-specific location.
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rc, _, err := smbios.Stream()
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if err != nil {
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return "", fmt.Errorf("failed to open dmi/smbios stream: %w", err)
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}
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defer rc.Close()
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// Decode SMBIOS structures from the stream.
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d := smbios.NewDecoder(rc)
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ss, err := d.Decode()
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if err != nil {
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return "", fmt.Errorf("failed to decode dmi/smbios structures: %w", err)
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}
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for _, s := range ss {
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if s.Header.Type == sysInfoHeaderType {
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serial, err := GetStringFromSmbiosStructure(s, serialNumberOffset)
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if err != nil {
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return "", fmt.Errorf("could not read serial from dmi/smbios structure: %w", err)
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}
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return serial, nil
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}
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}
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return "", fmt.Errorf("could not read serial from dmi/smbios structure: no data found")
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}
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