/
ruleset.go
231 lines (205 loc) · 5.34 KB
/
ruleset.go
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package main
import (
"fmt"
"net"
"regexp"
"github.com/miekg/dns"
)
const (
ActionForward = "forward"
ActionRefused = "refused"
ActionFailed = "failed"
)
type CompiledRuleSet struct {
Domains map[string]Domain
}
type Domain struct {
Name string
Ruleset []Rule
}
/*
func NewCompiledRuleSet(config *Config) (*CompiledRuleSet, error) {
rs := CompiledRuleSet{}
if err := rs.ParseConfig(config); err != nil {
return nil, err
}
return &rs, nil
}
*/
func (c *CompiledRuleSet) ParseConfig(config *Config) error {
domains := map[string]Domain{}
errs := []error{}
for domain, rulelist := range config.Rules {
domain = dns.Fqdn(domain)
rules := []Rule{}
for _, rule := range rulelist {
if r, err := newRule(rule); err == nil {
rules = append(rules, *r)
} else {
errs = append(errs, err)
}
}
domains[domain] = Domain{Name: domain, Ruleset: rules}
}
c.Domains = domains
if len(errs) > 0 {
return fmt.Errorf("errors parsing config: %s", errs)
}
return nil
}
func newRule(rc RuleConfig) (*Rule, error) {
errs := []error{}
rule := Rule{Name: rc.Name, Description: rc.Description}
for i, pattern := range rc.Match.Patterns {
if p, err := regexp.Compile(pattern); err == nil {
rule.Match.Patterns = append(rule.Match.Patterns, *p)
} else {
sugar.Warnf("pattern:%v fail to parse pattern: %s: %s", i, pattern, err)
errs = append(errs, err)
}
}
for i, iprange := range rc.Match.SourceIps {
if _, p, err := net.ParseCIDR(iprange); err == nil {
rule.Match.SourceIps = append(rule.Match.SourceIps, *p)
} else {
sugar.Warnf("range:%v fail to parse range: %s: %s", i, iprange, err)
errs = append(errs, err)
}
}
for i, qt := range rc.Match.QueryTypes {
if value, found := txt2dnstype[qt]; found {
rule.Match.QueryTypes = append(rule.Match.QueryTypes, value)
} else {
sugar.Warnf("query type:%v fail to find query type %s", i, qt)
errs = append(errs, fmt.Errorf("fail to find query type %s", qt))
}
}
for i, iprange := range rc.Then.Filter.AnsweredAddress.NotIn {
if _, p, err := net.ParseCIDR(iprange); err == nil {
rule.Then.Filter.AnsweredAddress.NotIn = append(rule.Then.Filter.AnsweredAddress.NotIn, *p)
} else {
sugar.Warnf("AnsweredAddress.NotIn range:%v fail to parse range: %s: %s", i, iprange, err)
errs = append(errs, err)
}
}
switch rc.Then.Action {
case ActionForward, ActionRefused, ActionFailed:
rule.Then.Action = rc.Then.Action
default:
sugar.Warnf("action type unknown: %s", rc.Then.Action)
errs = append(errs, fmt.Errorf("action type unknown: %s", rc.Then.Action))
}
for _, tgt := range rc.Then.Targets {
if host, _, err := net.SplitHostPort(tgt); err != nil {
sugar.Warnf("unable to parse target %s", tgt)
errs = append(errs, fmt.Errorf("unable to parse target %s", tgt))
} else if parsed := net.ParseIP(host); parsed == nil {
sugar.Warnf("unable to parse target %s", tgt)
errs = append(errs, fmt.Errorf("unable to parse target %s", tgt))
} else {
rule.Then.Targets = append(rule.Then.Targets, tgt)
}
}
if rule.Then.Action == "forward" && len(rule.Then.Targets) == 0 {
errs = append(errs, fmt.Errorf("then has forward action but no target"))
}
if len(errs) != 0 {
return nil, fmt.Errorf("multiple errors while parsing rule: %s", errs)
}
return &rule, nil
}
type Rule struct {
Name string
Description string
Match Match
Then Then
}
type Match struct {
SourceIps []net.IPNet
Patterns []regexp.Regexp
QueryTypes []uint16
AnsweredAddress AnsweredAddress
}
type AnsweredAddress struct {
NotIn []net.IPNet
}
type Filter struct {
AnsweredAddress AnsweredAddress
}
type Then struct {
Action string
Targets []string
Filter Filter
}
func (r *Rule) MatchQuestion(question dns.Question, canonicalized_name string, remoteAddr net.Addr) *Then {
var match bool
// query types against question.Qtype
if len(r.Match.QueryTypes) > 0 {
match = false
for _, qt := range r.Match.QueryTypes {
if qt == question.Qtype {
match = true
break
}
}
if !match {
return nil
}
}
// remote addr against remoteAddr
if len(r.Match.SourceIps) > 0 {
match = false
parsed_ip, _, _ := net.SplitHostPort(remoteAddr.String())
var remoteip = net.ParseIP(parsed_ip)
for _, valid_range := range r.Match.SourceIps {
if valid_range.Contains(remoteip) {
match = true
break
}
}
if !match {
return nil
}
}
// patterns against question.Name
if len(r.Match.Patterns) > 0 {
match = false
for _, pattern := range r.Match.Patterns {
if pattern.MatchString(canonicalized_name) {
match = true
break
}
}
if !match {
return nil
}
}
return &r.Then
}
func (r *Rule) CheckResponse(resp *dns.Msg) bool {
if len(r.Then.Filter.AnsweredAddress.NotIn) > 0 {
for _, rr_holder := range [][]dns.RR{resp.Answer, resp.Extra} {
for _, record := range rr_holder {
switch record.Header().Rrtype {
case dns.TypeA:
if typed_record, ok := record.(*dns.A); ok {
for _, iprange := range r.Then.Filter.AnsweredAddress.NotIn {
if iprange.Contains(typed_record.A) {
return false
}
}
}
case dns.TypeAAAA:
if typed_record, ok := record.(*dns.AAAA); ok {
for _, iprange := range r.Then.Filter.AnsweredAddress.NotIn {
if iprange.Contains(typed_record.AAAA) {
return false
}
}
}
}
}
}
}
return true
}