332 lines
8.8 KiB
Go
332 lines
8.8 KiB
Go
package waf
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import (
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"fmt"
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"os"
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"regexp"
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"github.com/antonmedv/expr"
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"github.com/antonmedv/expr/vm"
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corazatypes "github.com/crowdsecurity/coraza/v3/types"
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log "github.com/sirupsen/logrus"
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"gopkg.in/yaml.v2"
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)
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type Hook struct {
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Filter string `yaml:"filter"`
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FilterExpr *vm.Program `yaml:"-"`
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OnSuccess string `yaml:"on_success"`
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Apply []string `yaml:"apply"`
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ApplyExpr []*vm.Program `yaml:"-"`
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}
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// @tko : todo - debug mode
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func (h *Hook) Build() error {
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if h.Filter != "" {
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program, err := expr.Compile(h.Filter) //FIXME: opts
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if err != nil {
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return fmt.Errorf("unable to compile filter %s : %w", h.Filter, err)
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}
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h.FilterExpr = program
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}
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for _, apply := range h.Apply {
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program, err := expr.Compile(apply, GetExprWAFOptions(GetHookEnv(WaapRuntimeConfig{}, ParsedRequest{}))...)
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if err != nil {
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return fmt.Errorf("unable to compile apply %s : %w", apply, err)
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}
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h.ApplyExpr = append(h.ApplyExpr, program)
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}
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return nil
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}
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type WaapTempResponse struct {
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InBandInterrupt bool
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OutOfBandInterrupt bool
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Action string //allow, deny, captcha, log
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HTTPResponseCode int
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SendEvent bool //do we send an internal event on rule match
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}
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// runtime version of WaapConfig
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type WaapRuntimeConfig struct {
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Name string
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OutOfBandRules []WaapCollection
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InBandRules []WaapCollection
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DefaultRemediation string
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CompiledOnLoad []Hook
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CompiledPreEval []Hook
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CompiledOnMatch []Hook
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CompiledVariablesTracking []*regexp.Regexp
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Config *WaapConfig
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//those are ephemeral, created/destroyed with every req
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OutOfBandTx ExtendedTransaction //is it a good idea ?
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InBandTx ExtendedTransaction //is it a good idea ?
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Response WaapTempResponse
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}
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type WaapConfig struct {
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Name string `yaml:"name"`
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OutOfBandRules []string `yaml:"outofband_rules"`
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InBandRules []string `yaml:"inband_rules"`
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DefaultRemediation string `yaml:"default_remediation"`
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DefaultPassAction string `yaml:"default_pass_action"`
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BlockedHTTPCode int `yaml:"blocked_http_code"`
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PassedHTTPCode int `yaml:"passed_http_code"`
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OnLoad []Hook `yaml:"on_load"`
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PreEval []Hook `yaml:"pre_eval"`
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OnMatch []Hook `yaml:"on_match"`
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VariablesTracking []string `yaml:"variables_tracking"`
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}
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func (w *WaapRuntimeConfig) ClearResponse() {
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log.Infof("#-> %p", w)
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w.Response = WaapTempResponse{}
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log.Infof("-> %p", w.Config)
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w.Response.Action = w.Config.DefaultPassAction
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w.Response.HTTPResponseCode = w.Config.PassedHTTPCode
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w.Response.SendEvent = true
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}
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func (wc *WaapConfig) Load(file string) error {
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yamlFile, err := os.ReadFile(file)
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if err != nil {
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return fmt.Errorf("unable to read file %s : %s", file, err)
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}
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err = yaml.UnmarshalStrict(yamlFile, wc)
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if err != nil {
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return fmt.Errorf("unable to parse yaml file %s : %s", file, err)
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}
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if wc.Name == "" {
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return fmt.Errorf("name cannot be empty")
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}
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if wc.DefaultRemediation == "" {
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return fmt.Errorf("default_remediation cannot be empty")
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}
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if wc.BlockedHTTPCode == 0 {
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wc.BlockedHTTPCode = 403
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}
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if wc.PassedHTTPCode == 0 {
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wc.PassedHTTPCode = 200
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}
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if wc.DefaultPassAction == "" {
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wc.DefaultPassAction = "allow"
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}
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return nil
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}
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func (wc *WaapConfig) Build() (*WaapRuntimeConfig, error) {
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ret := &WaapRuntimeConfig{}
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ret.Name = wc.Name
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ret.Config = wc
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ret.DefaultRemediation = wc.DefaultRemediation
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//load rules
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for _, rule := range wc.OutOfBandRules {
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collection, err := LoadCollection(rule)
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if err != nil {
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return nil, fmt.Errorf("unable to load outofband rule %s : %s", rule, err)
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}
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ret.OutOfBandRules = append(ret.OutOfBandRules, collection)
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}
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for _, rule := range wc.InBandRules {
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collection, err := LoadCollection(rule)
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if err != nil {
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return nil, fmt.Errorf("unable to load inband rule %s : %s", rule, err)
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}
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ret.InBandRules = append(ret.InBandRules, collection)
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}
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//load hooks
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for _, hook := range wc.OnLoad {
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err := hook.Build()
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if err != nil {
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return nil, fmt.Errorf("unable to build on_load hook : %s", err)
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}
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ret.CompiledOnLoad = append(ret.CompiledOnLoad, hook)
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}
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for _, hook := range wc.PreEval {
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err := hook.Build()
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if err != nil {
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return nil, fmt.Errorf("unable to build pre_eval hook : %s", err)
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}
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ret.CompiledPreEval = append(ret.CompiledPreEval, hook)
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}
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for _, hook := range wc.OnMatch {
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err := hook.Build()
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if err != nil {
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return nil, fmt.Errorf("unable to build on_match hook : %s", err)
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}
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ret.CompiledOnMatch = append(ret.CompiledOnMatch, hook)
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}
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//variable tracking
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for _, variable := range wc.VariablesTracking {
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compiledVariableRule, err := regexp.Compile(variable)
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if err != nil {
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return nil, fmt.Errorf("cannot compile variable regexp %s: %w", variable, err)
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}
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ret.CompiledVariablesTracking = append(ret.CompiledVariablesTracking, compiledVariableRule)
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}
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return ret, nil
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}
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func (w *WaapRuntimeConfig) ProcessOnMatchRules(request ParsedRequest, response ResponseRequest) error {
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for _, rule := range w.CompiledOnMatch {
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if rule.FilterExpr != nil {
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output, err := expr.Run(rule.FilterExpr, map[string]interface{}{
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//"rules": rules, //is it still useful ?
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"req": request,
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})
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if err != nil {
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return fmt.Errorf("unable to run filter %s : %w", rule.Filter, err)
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}
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switch t := output.(type) {
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case bool:
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if !t {
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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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for _, applyExpr := range rule.ApplyExpr {
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_, err := expr.Run(applyExpr, map[string]interface{}{
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// "req": request,
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// "RemoveInbandRuleByID": w.RemoveInbandRuleByID,
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// "RemoveOutbandRuleByID": w.RemoveOutbandRuleByID,
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// "SetAction": response.SetAction,
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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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return nil
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}
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func (w *WaapRuntimeConfig) ProcessPreEvalRules(request ParsedRequest) error {
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for _, rule := range w.CompiledPreEval {
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if rule.FilterExpr != nil {
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output, err := expr.Run(rule.FilterExpr, GetHookEnv(*w, request))
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if err != nil {
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return fmt.Errorf("unable to run filter %s : %w", rule.Filter, err)
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}
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switch t := output.(type) {
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case bool:
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if !t {
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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 rule.ApplyExpr {
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_, err := expr.Run(applyExpr, GetHookEnv(*w, request))
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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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return nil
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}
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/* @sbl / @tko
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add the helpers to:
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- remove by id-range
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- remove by tag
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- set remediation by tag/id-range
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*/
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func (w *WaapRuntimeConfig) RemoveInbandRuleByID(id int) error {
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return w.InBandTx.RemoveRuleByIDWithError(id)
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}
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func (w *WaapRuntimeConfig) CancelEvent() error {
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w.Response.SendEvent = false
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return nil
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}
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func (w *WaapRuntimeConfig) SetActionnByID(id int, action string) error {
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panic("not implemented")
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return nil
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}
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func (w *WaapRuntimeConfig) RemoveOutbandRuleByID(id int) error {
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return w.OutOfBandTx.RemoveRuleByIDWithError(id)
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}
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func (w *WaapRuntimeConfig) SetAction(action string) error {
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w.Response.Action = action
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return nil
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}
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func (w *WaapRuntimeConfig) SetHTTPCode(code int) error {
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w.Response.HTTPResponseCode = code
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return nil
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}
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func (w *WaapRuntimeConfig) ProcessInBandRules(request ParsedRequest) (*corazatypes.Interruption, error) {
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for _, rule := range w.InBandRules {
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interrupt, err := rule.Eval(request)
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if err != nil {
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return nil, fmt.Errorf("unable to process inband rule %s : %s", rule.GetDisplayName(), err)
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}
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if interrupt != nil {
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return interrupt, nil
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}
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}
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return nil, nil
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}
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func (w *WaapRuntimeConfig) ProcessOutOfBandRules(request ParsedRequest) (*corazatypes.Interruption, error) {
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for _, rule := range w.OutOfBandRules {
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interrupt, err := rule.Eval(request)
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if err != nil {
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return nil, fmt.Errorf("unable to process inband rule %s : %s", rule.GetDisplayName(), err)
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}
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if interrupt != nil {
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return interrupt, nil
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}
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}
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return nil, nil
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}
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type BodyResponse struct {
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Action string `json:"action"`
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HTTPStatus int `json:"http_status"`
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}
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func (w *WaapRuntimeConfig) GenerateResponse(interrupted bool) (BodyResponse, error) {
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resp := BodyResponse{}
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//if there is no interrupt, we should allow with default code
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if !interrupted {
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resp.Action = w.Config.DefaultPassAction
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resp.HTTPStatus = w.Config.PassedHTTPCode
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return resp, nil
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}
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resp.Action = w.Config.DefaultRemediation
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resp.HTTPStatus = w.Config.BlockedHTTPCode
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return resp, nil
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}
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