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Moved hosts-syntax matching to DnsFilter

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This commit is contained in:
Andrey Meshkov
2018-10-29 15:46:58 +03:00
parent 234ab23557
commit 2b2a797cf7
6 changed files with 166 additions and 103 deletions
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120
dnsfilter/dnsfilter.go
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@@ -9,6 +9,7 @@ import (
"fmt"
"io/ioutil"
"log"
"net"
"net/http"
"regexp"
"strings"
@@ -56,6 +57,7 @@ type rule struct {
text string // text without @@ decorators or $ options
shortcut string // for speeding up lookup
originalText string // original text for reporting back to applications
ip net.IP // IP address (for the case when we're matching a hosts file)
// options
options []string // optional options after $
@@ -94,7 +96,7 @@ type Stats struct {
// Dnsfilter holds added rules and performs hostname matches against the rules
type Dnsfilter struct {
storage map[string]*rule // rule storage, not used for matching, needs to be key->value
storage map[string]bool // rule storage, not used for matching, just for filtering out duplicates
storageMutex sync.RWMutex
// rules are checked against these lists in the order defined here
@@ -121,11 +123,11 @@ const (
NotFilteredError // there was a transitive error during check
// reasons for filtering
FilteredBlackList // the host was matched to be advertising host
FilteredSafeBrowsing // the host was matched to be malicious/phishing
FilteredParental // the host was matched to be outside of parental control settings
FilteredInvalid // the request was invalid and was not processed
FilteredSafeSearch // the host was replaced with safesearch variant
FilteredBlackList // the host was matched to be advertising host
FilteredSafeBrowsing // the host was matched to be malicious/phishing
FilteredParental // the host was matched to be outside of parental control settings
FilteredInvalid // the request was invalid and was not processed
FilteredSafeSearch // the host was replaced with safesearch variant
)
// these variables need to survive coredns reload
@@ -137,9 +139,11 @@ var (
// Result holds state of hostname check
type Result struct {
IsFiltered bool `json:",omitempty"`
Reason Reason `json:",omitempty"`
Rule string `json:",omitempty"`
IsFiltered bool `json:",omitempty"` // True if the host name is filtered
Reason Reason `json:",omitempty"` // Reason for blocking / unblocking
Rule string `json:",omitempty"` // Original rule text
Ip net.IP `json:",omitempty"` // Not nil only in the case of a hosts file syntax
FilterID uint32 `json:",omitempty"` // Filter ID the rule belongs to
}
// Matched can be used to see if any match at all was found, no matter filtered or not
@@ -199,6 +203,7 @@ func (d *Dnsfilter) CheckHost(host string) (Result, error) {
//
type rulesTable struct {
rulesByHost map[string]*rule
rulesByShortcut map[string][]*rule
rulesLeftovers []*rule
sync.RWMutex
@@ -206,6 +211,7 @@ type rulesTable struct {
func newRulesTable() *rulesTable {
return &rulesTable{
rulesByHost: make(map[string]*rule),
rulesByShortcut: make(map[string][]*rule),
rulesLeftovers: make([]*rule, 0),
}
@@ -213,16 +219,27 @@ func newRulesTable() *rulesTable {
func (r *rulesTable) Add(rule *rule) {
r.Lock()
if len(rule.shortcut) == shortcutLength && enableFastLookup {
if rule.ip != nil {
// Hosts syntax
r.rulesByHost[rule.text] = rule
} else if //noinspection GoBoolExpressions
len(rule.shortcut) == shortcutLength && enableFastLookup {
// Adblock syntax with a shortcut
r.rulesByShortcut[rule.shortcut] = append(r.rulesByShortcut[rule.shortcut], rule)
} else {
// Adblock syntax -- too short to have a shortcut
r.rulesLeftovers = append(r.rulesLeftovers, rule)
}
r.Unlock()
}
func (r *rulesTable) matchByHost(host string) (Result, error) {
res, err := r.searchShortcuts(host)
// First: examine the hosts-syntax rules
res, err := r.searchByHost(host)
if err != nil {
return res, err
}
@@ -230,6 +247,16 @@ func (r *rulesTable) matchByHost(host string) (Result, error) {
return res, nil
}
// Second: examine the adblock-syntax rules with shortcuts
res, err = r.searchShortcuts(host)
if err != nil {
return res, err
}
if res.Reason.Matched() {
return res, nil
}
// Third: examine the others
res, err = r.searchLeftovers(host)
if err != nil {
return res, err
@@ -241,6 +268,17 @@ func (r *rulesTable) matchByHost(host string) (Result, error) {
return Result{}, nil
}
func (r *rulesTable) searchByHost(host string) (Result, error) {
rule, ok := r.rulesByHost[host]
if ok {
return rule.match(host)
}
return Result{}, nil
}
func (r *rulesTable) searchShortcuts(host string) (Result, error) {
// check in shortcuts first
for i := 0; i < len(host); i++ {
@@ -424,8 +462,21 @@ func (rule *rule) compile() error {
return nil
}
// Checks if the rule matches the specified host and returns a corresponding Result object
func (rule *rule) match(host string) (Result, error) {
res := Result{}
if rule.ip != nil && rule.text == host {
// This is a hosts-syntax rule -- just check that the hostname matches and return the result
return Result{
IsFiltered: true,
Reason: FilteredBlackList,
Rule: rule.originalText,
Ip: rule.ip,
FilterID: rule.listID,
}, nil
}
err := rule.compile()
if err != nil {
return res, err
@@ -686,6 +737,7 @@ func (d *Dnsfilter) AddRule(input string, filterListID uint32) error {
d.storageMutex.RUnlock()
if exists {
// already added
// TODO: Change the error type
return ErrInvalidSyntax
}
@@ -693,13 +745,20 @@ func (d *Dnsfilter) AddRule(input string, filterListID uint32) error {
return ErrInvalidSyntax
}
// First, check if this is a hosts-syntax rule
if d.parseEtcHosts(input, filterListID) {
// This is a valid hosts-syntax rule, no need for further parsing
return nil
}
// Start parsing the rule
rule := rule{
text: input, // will be modified
originalText: input,
listID: filterListID,
}
// mark rule as whitelist if it starts with @@
// Mark rule as whitelist if it starts with @@
if strings.HasPrefix(rule.text, "@@") {
rule.isWhitelist = true
rule.text = rule.text[2:]
@@ -712,6 +771,7 @@ func (d *Dnsfilter) AddRule(input string, filterListID uint32) error {
rule.extractShortcut()
//noinspection GoBoolExpressions
if !enableDelayedCompilation {
err := rule.compile()
if err != nil {
@@ -727,12 +787,44 @@ func (d *Dnsfilter) AddRule(input string, filterListID uint32) error {
}
d.storageMutex.Lock()
d.storage[input] = &rule
d.storage[input] = true
d.storageMutex.Unlock()
destination.Add(&rule)
return nil
}
// Parses the hosts-syntax rules. Returns false if the input string is not of hosts-syntax.
func (d *Dnsfilter) parseEtcHosts(input string, filterListID uint32) bool {
// Strip the trailing comment
ruleText := input
if pos := strings.IndexByte(ruleText, '#'); pos != -1 {
ruleText = ruleText[0:pos]
}
fields := strings.Fields(ruleText)
if len(fields) < 2 {
return false
}
addr := net.ParseIP(fields[0])
if addr == nil {
return false
}
d.storageMutex.Lock()
d.storage[input] = true
d.storageMutex.Unlock()
for _, host := range fields[1:] {
rule := rule{
text: host,
originalText: input,
listID: filterListID,
ip: addr,
}
d.blackList.Add(&rule)
}
return true
}
// matchHost is a low-level way to check only if hostname is filtered by rules, skipping expensive safebrowsing and parental lookups
func (d *Dnsfilter) matchHost(host string) (Result, error) {
lists := []*rulesTable{
@@ -761,7 +853,7 @@ func (d *Dnsfilter) matchHost(host string) (Result, error) {
func New() *Dnsfilter {
d := new(Dnsfilter)
d.storage = make(map[string]*rule)
d.storage = make(map[string]bool)
d.important = newRulesTable()
d.whiteList = newRulesTable()
d.blackList = newRulesTable()