mirror of
https://github.com/matrix-org/dendrite
synced 2024-09-08 20:25:36 +02:00
166 lines
4.3 KiB
Go
166 lines
4.3 KiB
Go
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package pushrules
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import (
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"encoding/json"
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"fmt"
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"strings"
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"github.com/matrix-org/gomatrixserverlib"
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)
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// A RuleSetEvaluator encapsulates context to evaluate an event
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// against a rule set.
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type RuleSetEvaluator struct {
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ec EvaluationContext
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ruleSet []kindAndRules
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}
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// An EvaluationContext gives a RuleSetEvaluator access to the
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// environment, for rules that require that.
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type EvaluationContext interface {
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// UserDisplayName returns the current user's display name.
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UserDisplayName() string
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// RoomMemberCount returns the number of members in the room of
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// the current event.
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RoomMemberCount() (int, error)
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// HasPowerLevel returns whether the user has at least the given
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// power in the room of the current event.
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HasPowerLevel(userID, levelKey string) (bool, error)
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}
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// A kindAndRules is just here to simplify iteration of the (ordered)
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// kinds of rules.
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type kindAndRules struct {
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Kind Kind
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Rules []*Rule
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}
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// NewRuleSetEvaluator creates a new evaluator for the given rule set.
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func NewRuleSetEvaluator(ec EvaluationContext, ruleSet *RuleSet) *RuleSetEvaluator {
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return &RuleSetEvaluator{
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ec: ec,
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ruleSet: []kindAndRules{
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{OverrideKind, ruleSet.Override},
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{ContentKind, ruleSet.Content},
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{RoomKind, ruleSet.Room},
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{SenderKind, ruleSet.Sender},
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{UnderrideKind, ruleSet.Underride},
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},
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}
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}
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// MatchEvent returns the first matching rule. Returns nil if there
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// was no match rule.
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func (rse *RuleSetEvaluator) MatchEvent(event *gomatrixserverlib.Event) (*Rule, error) {
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// TODO: server-default rules have lower priority than user rules,
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// but they are stored together with the user rules. It's a bit
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// unclear what the specification (11.14.1.4 Predefined rules)
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// means the ordering should be.
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//
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// The most reasonable interpretation is that default overrides
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// still have lower priority than user content rules, so we
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// iterate twice.
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for _, rsat := range rse.ruleSet {
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for _, defRules := range []bool{false, true} {
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for _, rule := range rsat.Rules {
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if rule.Default != defRules {
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continue
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}
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ok, err := ruleMatches(rule, rsat.Kind, event, rse.ec)
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if err != nil {
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return nil, err
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}
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if ok {
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return rule, nil
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}
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}
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}
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}
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// No matching rule.
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return nil, nil
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}
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func ruleMatches(rule *Rule, kind Kind, event *gomatrixserverlib.Event, ec EvaluationContext) (bool, error) {
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if !rule.Enabled {
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return false, nil
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}
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switch kind {
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case OverrideKind, UnderrideKind:
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for _, cond := range rule.Conditions {
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ok, err := conditionMatches(cond, event, ec)
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if err != nil {
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return false, err
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}
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if !ok {
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return false, nil
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}
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}
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return true, nil
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case ContentKind:
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// TODO: "These configure behaviour for (unencrypted) messages
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// that match certain patterns." - Does that mean "content.body"?
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return patternMatches("content.body", rule.Pattern, event)
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case RoomKind:
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return rule.RuleID == event.RoomID(), nil
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case SenderKind:
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return rule.RuleID == event.Sender(), nil
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default:
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return false, nil
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}
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}
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func conditionMatches(cond *Condition, event *gomatrixserverlib.Event, ec EvaluationContext) (bool, error) {
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switch cond.Kind {
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case EventMatchCondition:
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return patternMatches(cond.Key, cond.Pattern, event)
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case ContainsDisplayNameCondition:
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return patternMatches("content.body", ec.UserDisplayName(), event)
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case RoomMemberCountCondition:
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cmp, err := parseRoomMemberCountCondition(cond.Is)
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if err != nil {
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return false, fmt.Errorf("parsing room_member_count condition: %w", err)
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}
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n, err := ec.RoomMemberCount()
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if err != nil {
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return false, fmt.Errorf("RoomMemberCount failed: %w", err)
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}
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return cmp(n), nil
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case SenderNotificationPermissionCondition:
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return ec.HasPowerLevel(event.Sender(), cond.Key)
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default:
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return false, nil
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}
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}
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func patternMatches(key, pattern string, event *gomatrixserverlib.Event) (bool, error) {
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re, err := globToRegexp(pattern)
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if err != nil {
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return false, err
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}
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var eventMap map[string]interface{}
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if err = json.Unmarshal(event.JSON(), &eventMap); err != nil {
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return false, fmt.Errorf("parsing event: %w", err)
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}
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v, err := lookupMapPath(strings.Split(key, "."), eventMap)
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if err != nil {
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// An unknown path is a benign error that shouldn't stop rule
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// processing. It's just a non-match.
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return false, nil
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}
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return re.MatchString(fmt.Sprint(v)), nil
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}
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