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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package tls
import (
"crypto/x509"
"encoding/pem"
"strings"
)
// A CASet is a set of certificates.
type CASet struct {
bySubjectKeyId map[string][]*x509.Certificate
byName map[string][]*x509.Certificate
}
// NewCASet returns a new, empty CASet.
func NewCASet() *CASet {
return &CASet{
make(map[string][]*x509.Certificate),
make(map[string][]*x509.Certificate),
}
}
func nameToKey(name *x509.Name) string {
return strings.Join(name.Country, ",") + "/" + strings.Join(name.Organization, ",") + "/" + strings.Join(name.OrganizationalUnit, ",") + "/" + name.CommonName
}
// FindVerifiedParent attempts to find the certificate in s which has signed
// the given certificate. If no such certificate can be found or the signature
// doesn't match, it returns nil.
func (s *CASet) FindVerifiedParent(cert *x509.Certificate) (parent *x509.Certificate) {
var candidates []*x509.Certificate
if len(cert.AuthorityKeyId) > 0 {
candidates = s.bySubjectKeyId[string(cert.AuthorityKeyId)]
}
if len(candidates) == 0 {
candidates = s.byName[nameToKey(&cert.Issuer)]
}
for _, c := range candidates {
if cert.CheckSignatureFrom(c) == nil {
return c
}
}
return nil
}
// AddCert adds a certificate to the set
func (s *CASet) AddCert(cert *x509.Certificate) {
if len(cert.SubjectKeyId) > 0 {
keyId := string(cert.SubjectKeyId)
s.bySubjectKeyId[keyId] = append(s.bySubjectKeyId[keyId], cert)
}
name := nameToKey(&cert.Subject)
s.byName[name] = append(s.byName[name], cert)
}
// SetFromPEM attempts to parse a series of PEM encoded root certificates. It
// appends any certificates found to s and returns true if any certificates
// were successfully parsed. On many Linux systems, /etc/ssl/cert.pem will
// contains the system wide set of root CAs in a format suitable for this
// function.
func (s *CASet) SetFromPEM(pemCerts []byte) (ok bool) {
for len(pemCerts) > 0 {
var block *pem.Block
block, pemCerts = pem.Decode(pemCerts)
if block == nil {
break
}
if block.Type != "CERTIFICATE" || len(block.Headers) != 0 {
continue
}
cert, err := x509.ParseCertificate(block.Bytes)
if err != nil {
continue
}
s.AddCert(cert)
ok = true
}
return
}
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