frostfs-sdk-go/eacl/validator.go

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