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lms.go
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lms.go
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package dga
import (
"strings"
)
// LmsScoreOfDomain calculates the mean longest meaningful substring of a domain.
// It follows some special rules to increase accuracy. It returns a value between
// 0 and 100, representing the length-based percentage of the meaningful substring.
func LmsScoreOfDomain(domain string) float64 {
var totalScore float64
domain = strings.ToLower(domain)
subjects := strings.Split(domain, ".")
var totalLength int
for _, subject := range subjects {
totalLength += len(subject)
}
for _, subject := range subjects {
// calculate score, weigh it and add it
if len(subject) > 0 {
totalScore += LmsScore(subject) * (float64(len(subject)) / float64(totalLength))
}
}
return totalScore
}
// LmsScore calculates the longest meaningful substring of a domain. It returns a
// value between 0 and 100, representing the length-based percentage of the
// meaningful substring.
func LmsScore(subject string) float64 {
lmsStart := -1
lmsStop := -1
longestLms := 0
for i, c := range subject {
if int(c) >= int('a') && int(c) <= int('z') {
if lmsStart == -1 {
lmsStart = i
}
} else {
if lmsStart > -1 {
lmsStop = i
if lmsStop-lmsStart > longestLms {
longestLms = lmsStop - lmsStart
}
lmsStart = -1
}
}
}
if lmsStop == -1 {
longestLms = len(subject)
}
// fmt.Printf("algs: lms score of %s is %.2f\n", subject, (float64(longest_lms) * 100.0 / float64(len(subject))))
return (float64(longestLms) * 100.0 / float64(len(subject)))
}