isle/go/nebula/hostname.go

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package nebula
import (
"errors"
"regexp"
)
var hostNameRegexp = regexp.MustCompile(`^[a-z][a-z0-9\-]*$`)
// HostName is the name of a host in a network. HostNames may only have
// lowercase letters, numbers, and hyphens, and must start with a letter.
type HostName string
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// MarshalText casts the HostName to a byte string and returns it.
func (h HostName) MarshalText() ([]byte, error) {
return []byte(h), nil
}
// UnmarshalText parses and validates a HostName from a text string.
func (h *HostName) UnmarshalText(b []byte) error {
if !hostNameRegexp.Match(b) {
return errors.New("a host's name must start with a letter and only contain letters, numbers, and dashes")
}
*h = HostName(b)
return nil
}