Xray-core/common/strmatcher/ac_automaton_matcher.go

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package strmatcher
import (
"container/list"
)
const validCharCount = 53
type MatchType struct {
matchType Type
exist bool
}
const (
TrieEdge bool = true
FailEdge bool = false
)
type Edge struct {
edgeType bool
nextNode int
}
type ACAutomaton struct {
trie [][validCharCount]Edge
fail []int
exists []MatchType
count int
}
func newNode() [validCharCount]Edge {
var s [validCharCount]Edge
for i := range s {
s[i] = Edge{
edgeType: FailEdge,
nextNode: 0,
}
}
return s
}
var char2Index = []int{
'A': 0,
'a': 0,
'B': 1,
'b': 1,
'C': 2,
'c': 2,
'D': 3,
'd': 3,
'E': 4,
'e': 4,
'F': 5,
'f': 5,
'G': 6,
'g': 6,
'H': 7,
'h': 7,
'I': 8,
'i': 8,
'J': 9,
'j': 9,
'K': 10,
'k': 10,
'L': 11,
'l': 11,
'M': 12,
'm': 12,
'N': 13,
'n': 13,
'O': 14,
'o': 14,
'P': 15,
'p': 15,
'Q': 16,
'q': 16,
'R': 17,
'r': 17,
'S': 18,
's': 18,
'T': 19,
't': 19,
'U': 20,
'u': 20,
'V': 21,
'v': 21,
'W': 22,
'w': 22,
'X': 23,
'x': 23,
'Y': 24,
'y': 24,
'Z': 25,
'z': 25,
'!': 26,
'$': 27,
'&': 28,
'\'': 29,
'(': 30,
')': 31,
'*': 32,
'+': 33,
',': 34,
';': 35,
'=': 36,
':': 37,
'%': 38,
'-': 39,
'.': 40,
'_': 41,
'~': 42,
'0': 43,
'1': 44,
'2': 45,
'3': 46,
'4': 47,
'5': 48,
'6': 49,
'7': 50,
'8': 51,
'9': 52,
}
func NewACAutomaton() *ACAutomaton {
var ac = new(ACAutomaton)
ac.trie = append(ac.trie, newNode())
ac.fail = append(ac.fail, 0)
ac.exists = append(ac.exists, MatchType{
matchType: Full,
exist: false,
})
return ac
}
func (ac *ACAutomaton) Add(domain string, t Type) {
var node = 0
for i := len(domain) - 1; i >= 0; i-- {
var idx = char2Index[domain[i]]
if ac.trie[node][idx].nextNode == 0 {
ac.count++
if len(ac.trie) < ac.count+1 {
ac.trie = append(ac.trie, newNode())
ac.fail = append(ac.fail, 0)
ac.exists = append(ac.exists, MatchType{
matchType: Full,
exist: false,
})
}
ac.trie[node][idx] = Edge{
edgeType: TrieEdge,
nextNode: ac.count,
}
}
node = ac.trie[node][idx].nextNode
}
ac.exists[node] = MatchType{
matchType: t,
exist: true,
}
switch t {
case Domain:
ac.exists[node] = MatchType{
matchType: Full,
exist: true,
}
var idx = char2Index['.']
if ac.trie[node][idx].nextNode == 0 {
ac.count++
if len(ac.trie) < ac.count+1 {
ac.trie = append(ac.trie, newNode())
ac.fail = append(ac.fail, 0)
ac.exists = append(ac.exists, MatchType{
matchType: Full,
exist: false,
})
}
ac.trie[node][idx] = Edge{
edgeType: TrieEdge,
nextNode: ac.count,
}
}
node = ac.trie[node][idx].nextNode
ac.exists[node] = MatchType{
matchType: t,
exist: true,
}
default:
break
}
}
func (ac *ACAutomaton) Build() {
var queue = list.New()
for i := 0; i < validCharCount; i++ {
if ac.trie[0][i].nextNode != 0 {
queue.PushBack(ac.trie[0][i])
}
}
for {
var front = queue.Front()
if front == nil {
break
} else {
var node = front.Value.(Edge).nextNode
queue.Remove(front)
for i := 0; i < validCharCount; i++ {
if ac.trie[node][i].nextNode != 0 {
ac.fail[ac.trie[node][i].nextNode] = ac.trie[ac.fail[node]][i].nextNode
queue.PushBack(ac.trie[node][i])
} else {
ac.trie[node][i] = Edge{
edgeType: FailEdge,
nextNode: ac.trie[ac.fail[node]][i].nextNode,
}
}
}
}
}
}
func (ac *ACAutomaton) Match(s string) bool {
var node = 0
var fullMatch = true
// 1. the match string is all through trie edge. FULL MATCH or DOMAIN
// 2. the match string is through a fail edge. NOT FULL MATCH
// 2.1 Through a fail edge, but there exists a valid node. SUBSTR
for i := len(s) - 1; i >= 0; i-- {
var idx = char2Index[s[i]]
fullMatch = fullMatch && ac.trie[node][idx].edgeType
node = ac.trie[node][idx].nextNode
switch ac.exists[node].matchType {
case Substr:
return true
case Domain:
if fullMatch {
return true
}
default:
break
}
}
return fullMatch && ac.exists[node].exist
}