/
id.go
97 lines (82 loc) · 2.34 KB
/
id.go
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package device
import (
"fmt"
"net/http"
"regexp"
"strings"
"unicode"
)
// ID represents a normalized identifer for a device.
type ID string
// Bytes is a convenience function to obtain the []byte representation of an ID.
func (id ID) Bytes() []byte {
return []byte(id)
}
const (
hexDigits = "0123456789abcdefABCDEF"
macDelimiters = ":-.,"
macPrefix = "mac"
macLength = 12
)
var (
invalidID = ID("")
// idPattern is the precompiled regular expression that all device identifiers must match.
// Matching is partial, as everything after the service is ignored.
idPattern = regexp.MustCompile(
`^(?P<prefix>(?i)mac|uuid|dns|serial):(?P<id>[^/]+)(?P<service>/[^/]+)?`,
)
)
// IntToMAC accepts a 64-bit integer and formats that as a device MAC address identifier
// The returned ID will be of the form mac:XXXXXXXXXXXX, where X is a hexadecimal digit using
// lowercased letters.
func IntToMAC(value uint64) ID {
return ID(fmt.Sprintf("mac:%012x", value&0x0000FFFFFFFFFFFF))
}
// ParseID parses a raw device name into a canonicalized identifier.
func ParseID(deviceName string) (ID, error) {
match := idPattern.FindStringSubmatch(deviceName)
if match == nil {
return invalidID, ErrorInvalidDeviceName
}
var (
prefix = strings.ToLower(match[1])
idPart = match[2]
)
if prefix == macPrefix {
var invalidCharacter rune = -1
idPart = strings.Map(
func(r rune) rune {
switch {
case strings.ContainsRune(hexDigits, r):
return unicode.ToLower(r)
case strings.ContainsRune(macDelimiters, r):
return -1
default:
invalidCharacter = r
return -1
}
},
idPart,
)
if invalidCharacter != -1 || len(idPart) != macLength {
return invalidID, ErrorInvalidDeviceName
}
}
return ID(fmt.Sprintf("%s:%s", prefix, idPart)), nil
}
// IDHashParser is a parsing function that examines an HTTP request to produce
// a []byte key for consistent hashing. The returned function examines the
// given request header and invokes ParseID on the value.
//
// If deviceNameHeader is the empty string, DefaultDeviceNameHeader is used.
func IDHashParser(request *http.Request) ([]byte, error) {
deviceName := request.Header.Get(DeviceNameHeader)
if len(deviceName) == 0 {
return nil, ErrorMissingDeviceNameHeader
}
id, err := ParseID(deviceName)
if err != nil {
return nil, err
}
return id.Bytes(), nil
}