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|
package trustgraph
import (
"strings"
"github.com/containers/libtrust"
)
type grantNode struct {
grants []*Grant
children map[string]*grantNode
}
type memoryGraph struct {
roots map[string]*grantNode
}
func newGrantNode() *grantNode {
return &grantNode{
grants: []*Grant{},
children: map[string]*grantNode{},
}
}
// NewMemoryGraph returns a new in memory trust graph created from
// a static list of grants. This graph is immutable after creation
// and any alterations should create a new instance.
func NewMemoryGraph(grants []*Grant) TrustGraph {
roots := map[string]*grantNode{}
for _, grant := range grants {
parts := strings.Split(grant.Grantee, "/")
nodes := roots
var node *grantNode
var nodeOk bool
for _, part := range parts {
node, nodeOk = nodes[part]
if !nodeOk {
node = newGrantNode()
nodes[part] = node
}
if part != "" {
node.grants = append(node.grants, grant)
}
nodes = node.children
}
}
return &memoryGraph{roots}
}
func (g *memoryGraph) getGrants(name string) []*Grant {
nameParts := strings.Split(name, "/")
nodes := g.roots
var node *grantNode
var nodeOk bool
for _, part := range nameParts {
node, nodeOk = nodes[part]
if !nodeOk {
return nil
}
nodes = node.children
}
return node.grants
}
func isSubName(name, sub string) bool {
if strings.HasPrefix(name, sub) {
if len(name) == len(sub) || name[len(sub)] == '/' {
return true
}
}
return false
}
type walkFunc func(*Grant, []*Grant) bool
func foundWalkFunc(*Grant, []*Grant) bool {
return true
}
func (g *memoryGraph) walkGrants(start, target string, permission uint16, f walkFunc, chain []*Grant, visited map[*Grant]bool, collect bool) bool {
if visited == nil {
visited = map[*Grant]bool{}
}
grants := g.getGrants(start)
subGrants := make([]*Grant, 0, len(grants))
for _, grant := range grants {
if visited[grant] {
continue
}
visited[grant] = true
if grant.Permission&permission == permission {
if isSubName(target, grant.Subject) {
if f(grant, chain) {
return true
}
} else {
subGrants = append(subGrants, grant)
}
}
}
for _, grant := range subGrants {
var chainCopy []*Grant
if collect {
chainCopy = make([]*Grant, len(chain)+1)
copy(chainCopy, chain)
chainCopy[len(chainCopy)-1] = grant
} else {
chainCopy = nil
}
if g.walkGrants(grant.Subject, target, permission, f, chainCopy, visited, collect) {
return true
}
}
return false
}
func (g *memoryGraph) Verify(key libtrust.PublicKey, node string, permission uint16) (bool, error) {
return g.walkGrants(key.KeyID(), node, permission, foundWalkFunc, nil, nil, false), nil
}
func (g *memoryGraph) GetGrants(key libtrust.PublicKey, node string, permission uint16) ([][]*Grant, error) {
grants := [][]*Grant{}
collect := func(grant *Grant, chain []*Grant) bool {
grantChain := make([]*Grant, len(chain)+1)
copy(grantChain, chain)
grantChain[len(grantChain)-1] = grant
grants = append(grants, grantChain)
return false
}
g.walkGrants(key.KeyID(), node, permission, collect, nil, nil, true)
return grants, nil
}
|
