1 // Copyright 2011 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
14 type sum224 [sha256.Size224]byte
16 // CertPool is a set of certificates.
17 type CertPool struct {
18 byName map[string][]int // cert.RawSubject => index into lazyCerts
20 // lazyCerts contains funcs that return a certificate,
21 // lazily parsing/decompressing it as needed.
24 // haveSum maps from sum224(cert.Raw) to true. It's used only
25 // for AddCert duplicate detection, to avoid CertPool.contains
26 // calls in the AddCert path (because the contains method can
27 // call getCert and otherwise negate savings from lazy getCert
29 haveSum map[sum224]bool
31 // systemPool indicates whether this is a special pool derived from the
32 // system roots. If it includes additional roots, it requires doing two
33 // verifications, one using the roots provided by the caller, and one using
34 // the system platform verifier.
38 // lazyCert is minimal metadata about a Cert and a func to retrieve it
39 // in its normal expanded *Certificate form.
40 type lazyCert struct {
41 // rawSubject is the Certificate.RawSubject value.
42 // It's the same as the CertPool.byName key, but in []byte
43 // form to make CertPool.Subjects (as used by crypto/tls) do
47 // constraint is a function to run against a chain when it is a candidate to
48 // be added to the chain. This allows adding arbitrary constraints that are
49 // not specified in the certificate itself.
50 constraint func([]*Certificate) error
52 // getCert returns the certificate.
54 // It is not meant to do network operations or anything else
55 // where a failure is likely; the func is meant to lazily
56 // parse/decompress data that is already known to be good. The
57 // error in the signature primarily is meant for use in the
58 // case where a cert file existed on local disk when the program
59 // started up is deleted later before it's read.
60 getCert func() (*Certificate, error)
63 // NewCertPool returns a new, empty CertPool.
64 func NewCertPool() *CertPool {
66 byName: make(map[string][]int),
67 haveSum: make(map[sum224]bool),
71 // len returns the number of certs in the set.
72 // A nil set is a valid empty set.
73 func (s *CertPool) len() int {
77 return len(s.lazyCerts)
80 // cert returns cert index n in s.
81 func (s *CertPool) cert(n int) (*Certificate, func([]*Certificate) error, error) {
82 cert, err := s.lazyCerts[n].getCert()
83 return cert, s.lazyCerts[n].constraint, err
86 // Clone returns a copy of s.
87 func (s *CertPool) Clone() *CertPool {
89 byName: make(map[string][]int, len(s.byName)),
90 lazyCerts: make([]lazyCert, len(s.lazyCerts)),
91 haveSum: make(map[sum224]bool, len(s.haveSum)),
92 systemPool: s.systemPool,
94 for k, v := range s.byName {
95 indexes := make([]int, len(v))
99 for k := range s.haveSum {
102 copy(p.lazyCerts, s.lazyCerts)
106 // SystemCertPool returns a copy of the system cert pool.
108 // On Unix systems other than macOS the environment variables SSL_CERT_FILE and
109 // SSL_CERT_DIR can be used to override the system default locations for the SSL
110 // certificate file and SSL certificate files directory, respectively. The
111 // latter can be a colon-separated list.
113 // Any mutations to the returned pool are not written to disk and do not affect
114 // any other pool returned by SystemCertPool.
116 // New changes in the system cert pool might not be reflected in subsequent calls.
117 func SystemCertPool() (*CertPool, error) {
118 if sysRoots := systemRootsPool(); sysRoots != nil {
119 return sysRoots.Clone(), nil
122 return loadSystemRoots()
125 type potentialParent struct {
127 constraint func([]*Certificate) error
130 // findPotentialParents returns the certificates in s which might have signed
132 func (s *CertPool) findPotentialParents(cert *Certificate) []potentialParent {
137 // consider all candidates where cert.Issuer matches cert.Subject.
138 // when picking possible candidates the list is built in the order
139 // of match plausibility as to save cycles in buildChains:
140 // AKID and SKID match
141 // AKID present, SKID missing / AKID missing, SKID present
142 // AKID and SKID don't match
143 var matchingKeyID, oneKeyID, mismatchKeyID []potentialParent
144 for _, c := range s.byName[string(cert.RawIssuer)] {
145 candidate, constraint, err := s.cert(c)
149 kidMatch := bytes.Equal(candidate.SubjectKeyId, cert.AuthorityKeyId)
152 matchingKeyID = append(matchingKeyID, potentialParent{candidate, constraint})
153 case (len(candidate.SubjectKeyId) == 0 && len(cert.AuthorityKeyId) > 0) ||
154 (len(candidate.SubjectKeyId) > 0 && len(cert.AuthorityKeyId) == 0):
155 oneKeyID = append(oneKeyID, potentialParent{candidate, constraint})
157 mismatchKeyID = append(mismatchKeyID, potentialParent{candidate, constraint})
161 found := len(matchingKeyID) + len(oneKeyID) + len(mismatchKeyID)
165 candidates := make([]potentialParent, 0, found)
166 candidates = append(candidates, matchingKeyID...)
167 candidates = append(candidates, oneKeyID...)
168 candidates = append(candidates, mismatchKeyID...)
172 func (s *CertPool) contains(cert *Certificate) bool {
176 return s.haveSum[sha256.Sum224(cert.Raw)]
179 // AddCert adds a certificate to a pool.
180 func (s *CertPool) AddCert(cert *Certificate) {
182 panic("adding nil Certificate to CertPool")
184 s.addCertFunc(sha256.Sum224(cert.Raw), string(cert.RawSubject), func() (*Certificate, error) {
189 // addCertFunc adds metadata about a certificate to a pool, along with
190 // a func to fetch that certificate later when needed.
192 // The rawSubject is Certificate.RawSubject and must be non-empty.
193 // The getCert func may be called 0 or more times.
194 func (s *CertPool) addCertFunc(rawSum224 sum224, rawSubject string, getCert func() (*Certificate, error), constraint func([]*Certificate) error) {
196 panic("getCert can't be nil")
199 // Check that the certificate isn't being added twice.
200 if s.haveSum[rawSum224] {
204 s.haveSum[rawSum224] = true
205 s.lazyCerts = append(s.lazyCerts, lazyCert{
206 rawSubject: []byte(rawSubject),
208 constraint: constraint,
210 s.byName[rawSubject] = append(s.byName[rawSubject], len(s.lazyCerts)-1)
213 // AppendCertsFromPEM attempts to parse a series of PEM encoded certificates.
214 // It appends any certificates found to s and reports whether any certificates
215 // were successfully parsed.
217 // On many Linux systems, /etc/ssl/cert.pem will contain the system wide set
218 // of root CAs in a format suitable for this function.
219 func (s *CertPool) AppendCertsFromPEM(pemCerts []byte) (ok bool) {
220 for len(pemCerts) > 0 {
222 block, pemCerts = pem.Decode(pemCerts)
226 if block.Type != "CERTIFICATE" || len(block.Headers) != 0 {
230 certBytes := block.Bytes
231 cert, err := ParseCertificate(certBytes)
235 var lazyCert struct {
239 s.addCertFunc(sha256.Sum224(cert.Raw), string(cert.RawSubject), func() (*Certificate, error) {
241 // This can't fail, as the same bytes already parsed above.
242 lazyCert.v, _ = ParseCertificate(certBytes)
245 return lazyCert.v, nil
253 // Subjects returns a list of the DER-encoded subjects of
254 // all of the certificates in the pool.
256 // Deprecated: if s was returned by [SystemCertPool], Subjects
257 // will not include the system roots.
258 func (s *CertPool) Subjects() [][]byte {
259 res := make([][]byte, s.len())
260 for i, lc := range s.lazyCerts {
261 res[i] = lc.rawSubject
266 // Equal reports whether s and other are equal.
267 func (s *CertPool) Equal(other *CertPool) bool {
268 if s == nil || other == nil {
271 if s.systemPool != other.systemPool || len(s.haveSum) != len(other.haveSum) {
274 for h := range s.haveSum {
275 if !other.haveSum[h] {
282 // AddCertWithConstraint adds a certificate to the pool with the additional
283 // constraint. When Certificate.Verify builds a chain which is rooted by cert,
284 // it will additionally pass the whole chain to constraint to determine its
285 // validity. If constraint returns a non-nil error, the chain will be discarded.
286 // constraint may be called concurrently from multiple goroutines.
287 func (s *CertPool) AddCertWithConstraint(cert *Certificate, constraint func([]*Certificate) error) {
289 panic("adding nil Certificate to CertPool")
291 s.addCertFunc(sha256.Sum224(cert.Raw), string(cert.RawSubject), func() (*Certificate, error) {