131 lines
2.9 KiB
Go
131 lines
2.9 KiB
Go
package eacl
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import (
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"bytes"
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)
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// Validator is a tool that calculates
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// the action on a request according
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// to the extended ACL rule table.
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type Validator struct{}
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// NewValidator creates and initializes a new Validator using options.
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func NewValidator() *Validator {
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return &Validator{}
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}
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// CalculateAction calculates action on the request according
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// to its information represented in ValidationUnit.
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//
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// The action is calculated according to the application of
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// eACL table of rules to the request.
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//
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// Second return value is true iff the action was produced by a matching entry.
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//
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// If no matching table entry is found or some filters are missing,
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// ActionAllow is returned and the second return value is false.
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func (v *Validator) CalculateAction(unit *ValidationUnit) (Action, bool) {
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for _, record := range unit.table.Records() {
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// check type of operation
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if record.Operation() != unit.op {
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continue
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}
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// check target
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if !targetMatches(unit, &record) {
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continue
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}
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// check headers
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switch val := matchFilters(unit.hdrSrc, record.Filters()); {
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case val < 0:
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// headers of some type could not be composed => allow
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return ActionAllow, false
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case val == 0:
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return record.Action(), true
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}
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}
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return ActionAllow, false
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}
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// returns:
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// - positive value if no matching header is found for at least one filter;
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// - zero if at least one suitable header is found for all filters;
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// - negative value if the headers of at least one filter cannot be obtained.
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func matchFilters(hdrSrc TypedHeaderSource, filters []Filter) int {
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matched := 0
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for _, filter := range filters {
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headers, ok := hdrSrc.HeadersOfType(filter.From())
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if !ok {
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return -1
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}
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// get headers of filtering type
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for _, header := range headers {
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// prevent NPE
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if header == nil {
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continue
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}
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// check header name
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if header.Key() != filter.Key() {
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continue
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}
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// get match function
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matchFn, ok := mMatchFns[filter.Matcher()]
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if !ok {
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continue
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}
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// check match
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if !matchFn(header, &filter) {
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continue
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}
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// increment match counter
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matched++
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break
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}
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}
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return len(filters) - matched
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}
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// returns true if one of ExtendedACLTarget has
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// suitable target OR suitable public key.
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func targetMatches(unit *ValidationUnit, record *Record) bool {
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for _, target := range record.Targets() {
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// check public key match
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if pubs := target.BinaryKeys(); len(pubs) != 0 {
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for _, key := range pubs {
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if bytes.Equal(key, unit.key) {
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return true
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}
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}
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continue
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}
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// check target group match
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if unit.role == target.Role() {
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return true
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}
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}
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return false
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}
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// Maps match type to corresponding function.
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var mMatchFns = map[Match]func(Header, *Filter) bool{
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MatchStringEqual: func(header Header, filter *Filter) bool {
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return header.Value() == filter.Value()
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},
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MatchStringNotEqual: func(header Header, filter *Filter) bool {
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return header.Value() != filter.Value()
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},
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}
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