543 lines
14 KiB
Go
543 lines
14 KiB
Go
package wafacquisition
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import (
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"context"
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"encoding/json"
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"fmt"
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"net/http"
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"os"
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"strings"
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"github.com/antonmedv/expr"
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"github.com/corazawaf/coraza/v3"
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"github.com/corazawaf/coraza/v3/experimental"
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corazatypes "github.com/corazawaf/coraza/v3/types"
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"github.com/crowdsecurity/crowdsec/pkg/acquisition/configuration"
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"github.com/crowdsecurity/crowdsec/pkg/types"
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"github.com/crowdsecurity/crowdsec/pkg/waf"
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"github.com/crowdsecurity/go-cs-lib/pkg/trace"
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"github.com/google/uuid"
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"github.com/pkg/errors"
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"github.com/prometheus/client_golang/prometheus"
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log "github.com/sirupsen/logrus"
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"gopkg.in/tomb.v2"
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"gopkg.in/yaml.v2"
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)
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const (
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InBand = "inband"
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OutOfBand = "outofband"
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)
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type WafRunner struct {
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outChan chan types.Event
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inChan chan waf.ParsedRequest
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inBandWaf coraza.WAF
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outOfBandWaf coraza.WAF
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UUID string
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RulesCollections []*waf.WafRulesCollection
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}
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type WafSourceConfig struct {
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ListenAddr string `yaml:"listen_addr"`
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ListenPort int `yaml:"listen_port"`
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Path string `yaml:"path"`
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WafRoutines int `yaml:"waf_routines"`
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configuration.DataSourceCommonCfg `yaml:",inline"`
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}
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type WafSource struct {
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config WafSourceConfig
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logger *log.Entry
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mux *http.ServeMux
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server *http.Server
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addr string
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outChan chan types.Event
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InChan chan waf.ParsedRequest
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inBandWaf coraza.WAF
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outOfBandWaf coraza.WAF
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RulesCollections []*waf.WafRulesCollection
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WafRunners []WafRunner
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}
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func (w *WafSource) GetMetrics() []prometheus.Collector {
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return nil
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}
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func (w *WafSource) GetAggregMetrics() []prometheus.Collector {
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return nil
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}
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func (w *WafSource) UnmarshalConfig(yamlConfig []byte) error {
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wafConfig := WafSourceConfig{}
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err := yaml.UnmarshalStrict(yamlConfig, &wafConfig)
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if err != nil {
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return errors.Wrap(err, "Cannot parse waf configuration")
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}
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w.config = wafConfig
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if w.config.ListenAddr == "" {
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return fmt.Errorf("listen_addr cannot be empty")
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}
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if w.config.ListenPort == 0 {
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return fmt.Errorf("listen_port cannot be empty")
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}
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//FIXME: is that really needed ?
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if w.config.Path == "" {
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return fmt.Errorf("path cannot be empty")
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}
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if w.config.Path[0] != '/' {
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w.config.Path = "/" + w.config.Path
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}
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if w.config.Mode == "" {
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w.config.Mode = configuration.TAIL_MODE
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}
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return nil
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}
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func logError(error corazatypes.MatchedRule) {
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msg := error.ErrorLog(0)
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log.Infof("[logError][%s] %s", error.Rule().Severity(), msg)
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}
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func (w *WafSource) Configure(yamlConfig []byte, logger *log.Entry) error {
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err := w.UnmarshalConfig(yamlConfig)
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if err != nil {
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return errors.Wrap(err, "Cannot parse waf configuration")
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}
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w.logger = logger
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w.logger.Tracef("WAF configuration: %+v", w.config)
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w.addr = fmt.Sprintf("%s:%d", w.config.ListenAddr, w.config.ListenPort)
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w.mux = http.NewServeMux()
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w.server = &http.Server{
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Addr: w.addr,
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Handler: w.mux,
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}
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ruleLoader := waf.NewWafRuleLoader()
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rulesCollections, err := ruleLoader.LoadWafRules()
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if err != nil {
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return fmt.Errorf("cannot load WAF rules: %w", err)
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}
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w.RulesCollections = rulesCollections
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var inBandRules string
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var outOfBandRules string
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//spew.Dump(rulesCollections)
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for _, collection := range rulesCollections {
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if !collection.OutOfBand {
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inBandRules += collection.String() + "\n"
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} else {
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outOfBandRules += collection.String() + "\n"
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}
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}
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w.logger.Infof("Loading %d in-band rules", len(strings.Split(inBandRules, "\n")))
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//w.logger.Infof("Loading rules %+v", inBandRules)
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fs := os.DirFS(ruleLoader.Datadir)
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// always have at least one waf routine
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if w.config.WafRoutines == 0 {
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w.config.WafRoutines = 1
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}
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w.InChan = make(chan waf.ParsedRequest)
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w.WafRunners = make([]WafRunner, w.config.WafRoutines)
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for nbRoutine := 0; nbRoutine < w.config.WafRoutines; nbRoutine++ {
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w.logger.Infof("Loading %d in-band rules", len(strings.Split(inBandRules, "\n")))
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//in-band waf : kill on sight
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inbandwaf, err := coraza.NewWAF(
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coraza.NewWAFConfig().
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//WithErrorCallback(logError).
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WithDirectives(inBandRules).WithRootFS(fs),
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)
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if err != nil {
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return errors.Wrap(err, "Cannot create WAF")
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}
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w.logger.Infof("Loading %d out-of-band rules", len(strings.Split(outOfBandRules, "\n")))
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//out-of-band waf : log only
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outofbandwaf, err := coraza.NewWAF(
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coraza.NewWAFConfig().
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//WithErrorCallback(logError).
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WithDirectives(outOfBandRules).WithRootFS(fs),
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)
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if err != nil {
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return errors.Wrap(err, "Cannot create WAF")
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}
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runner := WafRunner{
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outOfBandWaf: outofbandwaf,
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inBandWaf: inbandwaf,
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inChan: w.InChan,
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UUID: uuid.New().String(),
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RulesCollections: rulesCollections,
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}
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w.WafRunners[nbRoutine] = runner
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}
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w.logger.Infof("Loading %d out-of-band rules", len(strings.Split(outOfBandRules, "\n")))
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if err != nil {
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return errors.Wrap(err, "Cannot create WAF")
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}
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//We don´t use the wrapper provided by coraza because we want to fully control what happens when a rule match to send the information in crowdsec
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w.mux.HandleFunc(w.config.Path, w.wafHandler)
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return nil
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}
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func (w *WafSource) ConfigureByDSN(dsn string, labels map[string]string, logger *log.Entry, uuid string) error {
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return fmt.Errorf("WAF datasource does not support command line acquisition")
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}
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func (w *WafSource) GetMode() string {
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return w.config.Mode
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}
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func (w *WafSource) GetName() string {
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return "waf"
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}
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func (w *WafSource) OneShotAcquisition(out chan types.Event, t *tomb.Tomb) error {
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return fmt.Errorf("WAF datasource does not support command line acquisition")
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}
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func (w *WafSource) StreamingAcquisition(out chan types.Event, t *tomb.Tomb) error {
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w.outChan = out
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t.Go(func() error {
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defer trace.CatchPanic("crowdsec/acquis/waf/live")
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w.logger.Infof("%d waf runner to start", len(w.WafRunners))
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for _, runner := range w.WafRunners {
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w.logger.Infof("Running waf runner: %s", runner.UUID)
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runner.outChan = out
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t.Go(func() error {
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return runner.Run(t)
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})
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}
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w.logger.Infof("Starting WAF server on %s:%d%s", w.config.ListenAddr, w.config.ListenPort, w.config.Path)
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t.Go(func() error {
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err := w.server.ListenAndServe()
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if err != nil && err != http.ErrServerClosed {
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return errors.Wrap(err, "WAF server failed")
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}
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return nil
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})
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<-t.Dying()
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w.logger.Infof("Stopping WAF server on %s:%d%s", w.config.ListenAddr, w.config.ListenPort, w.config.Path)
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w.server.Shutdown(context.TODO())
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return nil
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})
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return nil
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}
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func (w *WafSource) CanRun() error {
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return nil
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}
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func (w *WafSource) GetUuid() string {
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return w.config.UniqueId
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}
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func (w *WafSource) Dump() interface{} {
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return w
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}
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func processReqWithEngine(tx experimental.FullTransaction, r waf.ParsedRequest, wafType string) (*corazatypes.Interruption, experimental.FullTransaction, error) {
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var in *corazatypes.Interruption
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if tx.IsRuleEngineOff() {
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log.Printf("engine is off")
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return nil, nil, nil
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}
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defer func() {
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tx.ProcessLogging()
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tx.Close()
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}()
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//this method is not exported by coraza, so we have to do it ourselves.
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//ideally, this would be dealt with by expr code, and we provide helpers to manipulate the transaction object?\
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//var txx experimental.FullTransaction
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//txx := experimental.ToFullInterface(tx)
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//txx = tx.(experimental.FullTransaction)
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//txx.RemoveRuleByID(1)
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tx.ProcessConnection(r.ClientIP, 0, "", 0)
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//tx.ProcessURI(r.URL.String(), r.Method, r.Proto) //FIXME: get it from the headers
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tx.ProcessURI(r.URI, r.Method, r.Proto) //FIXME: get it from the headers
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for k, vr := range r.Headers {
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for _, v := range vr {
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tx.AddRequestHeader(k, v)
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}
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}
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if r.ClientHost != "" {
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tx.AddRequestHeader("Host", r.ClientHost)
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// This connector relies on the host header (now host field) to populate ServerName
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tx.SetServerName(r.ClientHost)
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}
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if r.TransferEncoding != nil {
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tx.AddRequestHeader("Transfer-Encoding", r.TransferEncoding[0])
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}
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in = tx.ProcessRequestHeaders()
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//spew.Dump(in)
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//spew.Dump(tx.MatchedRules())
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for _, rule := range tx.MatchedRules() {
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if rule.Message() == "" {
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continue
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}
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}
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//if we're inband, we should stop here, but for outofband go to the end
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if in != nil && wafType == InBand {
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return in, tx, nil
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}
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ct := r.Headers.Get("content-type")
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if r.Body != nil && len(r.Body) != 0 {
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it, _, err := tx.WriteRequestBody(r.Body)
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if err != nil {
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return nil, nil, errors.Wrap(err, "Cannot read request body")
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}
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if it != nil {
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return it, nil, nil
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}
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// from https://github.com/corazawaf/coraza/blob/main/internal/corazawaf/transaction.go#L419
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// urlencoded cannot end with CRLF
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if ct != "application/x-www-form-urlencoded" {
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it, _, err := tx.WriteRequestBody([]byte{'\r', '\n'})
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if err != nil {
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return nil, nil, fmt.Errorf("cannot write to request body to buffer: %s", err.Error())
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}
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if it != nil {
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return it, nil, nil
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}
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}
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}
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in, err := tx.ProcessRequestBody()
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if err != nil {
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return nil, nil, errors.Wrap(err, "Cannot process request body")
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}
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if in != nil && wafType == InBand {
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return in, tx, nil
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}
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return nil, tx, nil
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}
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func (r *WafRunner) Run(t *tomb.Tomb) error {
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for {
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select {
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case <-t.Dying():
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log.Infof("Waf Runner is dying")
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return nil
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case request := <-r.inChan:
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inBoundTx := r.inBandWaf.NewTransactionWithID(request.UUID)
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expTx := inBoundTx.(experimental.FullTransaction)
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// we use this internal transaction for the expr helpers
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tx := waf.NewTransaction(expTx)
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//Run the pre_eval hooks
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for _, rules := range r.RulesCollections {
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if len(rules.CompiledPreEval) == 0 {
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continue
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}
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for _, compiledHook := range rules.CompiledPreEval {
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if compiledHook.Filter != nil {
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res, err := expr.Run(compiledHook.Filter, map[string]interface{}{
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"rules": rules,
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"req": request,
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})
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if err != nil {
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log.Errorf("unable to run PreEval filter: %s", err)
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continue
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}
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switch t := res.(type) {
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case bool:
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if t == false {
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log.Infof("filter didnt match")
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continue
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}
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default:
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log.Errorf("Filter must return a boolean, can't filter")
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continue
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}
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}
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// here means there is no filter or the filter matched
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for _, applyExpr := range compiledHook.Apply {
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_, err := expr.Run(applyExpr, map[string]interface{}{
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"rules": rules,
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"req": request,
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"RemoveRuleByID": tx.RemoveRuleByIDWithError,
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})
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if err != nil {
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log.Errorf("unable to apply filter: %s", err)
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continue
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}
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}
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}
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}
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in, expTx, err := processReqWithEngine(expTx, request, InBand)
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request.Tx = expTx
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response := waf.NewResponseRequest(expTx, in, request.UUID, err)
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// run the on_match hooks
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for _, rules := range r.RulesCollections {
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if len(rules.CompiledOnMatch) == 0 {
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continue
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}
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for _, compiledHook := range rules.CompiledOnMatch {
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if compiledHook.Filter != nil {
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res, err := expr.Run(compiledHook.Filter, map[string]interface{}{
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"rules": rules,
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"req": request,
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})
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if err != nil {
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log.Errorf("unable to run PreEval filter: %s", err)
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continue
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}
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switch t := res.(type) {
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case bool:
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if t == false {
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continue
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}
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default:
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log.Errorf("Filter must return a boolean, can't filter")
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continue
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}
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}
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// here means there is no filter or the filter matched
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for _, applyExpr := range compiledHook.Apply {
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_, err := expr.Run(applyExpr, map[string]interface{}{
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"rules": rules,
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"req": request,
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"RemoveRuleByID": tx.RemoveRuleByIDWithError,
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"SetRemediation": response.SetRemediation,
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"SetRemediationByID": response.SetRemediationByID,
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"CancelEvent": response.CancelEvent,
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})
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if err != nil {
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log.Errorf("unable to apply filter: %s", err)
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continue
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}
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}
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}
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}
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// send back the result to the HTTP handler for the InBand part
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request.ResponseChannel <- response
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if in != nil && response.SendEvents {
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// Generate the events for InBand channel
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events, err := TxToEvents(request, InBand)
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if err != nil {
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log.Errorf("Cannot convert transaction to events : %s", err)
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continue
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}
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for _, evt := range events {
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r.outChan <- evt
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}
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}
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// Process outBand
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outBandTx := r.outOfBandWaf.NewTransactionWithID(request.UUID)
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expTx = outBandTx.(experimental.FullTransaction)
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in, expTx, err = processReqWithEngine(expTx, request, OutOfBand)
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if err != nil { //things went south
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log.Errorf("Error while processing request : %s", err)
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continue
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}
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request.Tx = expTx
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if expTx != nil && len(expTx.MatchedRules()) > 0 {
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events, err := TxToEvents(request, OutOfBand)
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log.Infof("Request triggered by WAF, %d events to send", len(events))
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for _, evt := range events {
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r.outChan <- evt
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}
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if err != nil {
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log.Errorf("Cannot convert transaction to events : %s", err)
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continue
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}
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}
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}
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}
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}
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type BodyResponse struct {
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Action string `json:"action"`
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}
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func (w *WafSource) wafHandler(rw http.ResponseWriter, r *http.Request) {
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// parse the request only once
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parsedRequest, err := waf.NewParsedRequestFromRequest(r)
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if err != nil {
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log.Errorf("%s", err)
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rw.WriteHeader(http.StatusForbidden)
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return
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}
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w.InChan <- parsedRequest
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message := <-parsedRequest.ResponseChannel
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if message.Err != nil {
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log.Errorf("Error while processing InBAND: %s", err)
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rw.WriteHeader(http.StatusOK)
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return
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}
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if message.Interruption != nil {
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rw.WriteHeader(http.StatusForbidden)
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body, err := json.Marshal(BodyResponse{Action: message.Interruption.Action})
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if err != nil {
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log.Errorf("unable to build response: %s", err)
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} else {
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rw.Write(body)
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}
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return
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}
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rw.WriteHeader(http.StatusOK)
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body, err := json.Marshal(BodyResponse{Action: "allow"})
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if err != nil {
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log.Errorf("unable to build response: %s", err)
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} else {
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rw.Write(body)
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}
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return
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}
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