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domain.go
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domain.go
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package trie
import (
"errors"
"strings"
)
const (
wildcard = "*"
dotWildcard = ""
complexWildcard = "+"
domainStep = "."
)
// ErrInvalidDomain means insert domain is invalid
var ErrInvalidDomain = errors.New("invalid domain")
// DomainTrie contains the main logic for adding and searching nodes for domain segments.
// support wildcard domain (e.g *.google.com)
type DomainTrie struct {
root *Node
}
func ValidAndSplitDomain(domain string) ([]string, bool) {
if domain != "" && domain[len(domain)-1] == '.' {
return nil, false
}
parts := strings.Split(domain, domainStep)
if len(parts) == 1 {
if parts[0] == "" {
return nil, false
}
return parts, true
}
for _, part := range parts[1:] {
if part == "" {
return nil, false
}
}
return parts, true
}
// Insert adds a node to the trie.
// Support
// 1. www.example.com
// 2. *.example.com
// 3. subdomain.*.example.com
// 4. .example.com
// 5. +.example.com
func (t *DomainTrie) Insert(domain string, data any) error {
parts, valid := ValidAndSplitDomain(domain)
if !valid {
return ErrInvalidDomain
}
if parts[0] == complexWildcard {
t.insert(parts[1:], data)
parts[0] = dotWildcard
t.insert(parts, data)
} else {
t.insert(parts, data)
}
return nil
}
func (t *DomainTrie) insert(parts []string, data any) {
node := t.root
// reverse storage domain part to save space
for i := len(parts) - 1; i >= 0; i-- {
part := parts[i]
if !node.hasChild(part) {
node.addChild(part, newNode(nil))
}
node = node.getChild(part)
}
node.Data = data
}
// Search is the most important part of the Trie.
// Priority as:
// 1. static part
// 2. wildcard domain
// 2. dot wildcard domain
func (t *DomainTrie) Search(domain string) *Node {
parts, valid := ValidAndSplitDomain(domain)
if !valid || parts[0] == "" {
return nil
}
n := t.search(t.root, parts)
if n == nil || n.Data == nil {
return nil
}
return n
}
func (t *DomainTrie) search(node *Node, parts []string) *Node {
if len(parts) == 0 {
return node
}
if c := node.getChild(parts[len(parts)-1]); c != nil {
if n := t.search(c, parts[:len(parts)-1]); n != nil && n.Data != nil {
return n
}
}
if c := node.getChild(wildcard); c != nil {
if n := t.search(c, parts[:len(parts)-1]); n != nil && n.Data != nil {
return n
}
}
return node.getChild(dotWildcard)
}
// New returns a new, empty Trie.
func New() *DomainTrie {
return &DomainTrie{root: newNode(nil)}
}