1=pod 2 3=begin comment 4 5Any keypair function here that gets deprecated should be moved to 6d2i_RSAPrivateKey.pod. 7 8=end comment 9 10=head1 NAME 11 12d2i_ACCESS_DESCRIPTION, 13d2i_ADMISSIONS, 14d2i_ADMISSION_SYNTAX, 15d2i_ASIdOrRange, 16d2i_ASIdentifierChoice, 17d2i_ASIdentifiers, 18d2i_ASN1_BIT_STRING, 19d2i_ASN1_BMPSTRING, 20d2i_ASN1_ENUMERATED, 21d2i_ASN1_GENERALIZEDTIME, 22d2i_ASN1_GENERALSTRING, 23d2i_ASN1_IA5STRING, 24d2i_ASN1_INTEGER, 25d2i_ASN1_NULL, 26d2i_ASN1_OBJECT, 27d2i_ASN1_OCTET_STRING, 28d2i_ASN1_PRINTABLE, 29d2i_ASN1_PRINTABLESTRING, 30d2i_ASN1_SEQUENCE_ANY, 31d2i_ASN1_SET_ANY, 32d2i_ASN1_T61STRING, 33d2i_ASN1_TIME, 34d2i_ASN1_TYPE, 35d2i_ASN1_UINTEGER, 36d2i_ASN1_UNIVERSALSTRING, 37d2i_ASN1_UTCTIME, 38d2i_ASN1_UTF8STRING, 39d2i_ASN1_VISIBLESTRING, 40d2i_ASRange, 41d2i_AUTHORITY_INFO_ACCESS, 42d2i_AUTHORITY_KEYID, 43d2i_BASIC_CONSTRAINTS, 44d2i_CERTIFICATEPOLICIES, 45d2i_CMS_ContentInfo, 46d2i_CMS_ReceiptRequest, 47d2i_CMS_bio, 48d2i_CRL_DIST_POINTS, 49d2i_DHxparams, 50d2i_DIRECTORYSTRING, 51d2i_DISPLAYTEXT, 52d2i_DIST_POINT, 53d2i_DIST_POINT_NAME, 54d2i_DSA_SIG, 55d2i_ECDSA_SIG, 56d2i_ECPKParameters, 57d2i_EDIPARTYNAME, 58d2i_ESS_CERT_ID, 59d2i_ESS_CERT_ID_V2, 60d2i_ESS_ISSUER_SERIAL, 61d2i_ESS_SIGNING_CERT, 62d2i_ESS_SIGNING_CERT_V2, 63d2i_EXTENDED_KEY_USAGE, 64d2i_GENERAL_NAME, 65d2i_GENERAL_NAMES, 66d2i_IPAddressChoice, 67d2i_IPAddressFamily, 68d2i_IPAddressOrRange, 69d2i_IPAddressRange, 70d2i_ISSUER_SIGN_TOOL, 71d2i_ISSUING_DIST_POINT, 72d2i_NAMING_AUTHORITY, 73d2i_NETSCAPE_CERT_SEQUENCE, 74d2i_NETSCAPE_SPKAC, 75d2i_NETSCAPE_SPKI, 76d2i_NOTICEREF, 77d2i_OCSP_BASICRESP, 78d2i_OCSP_CERTID, 79d2i_OCSP_CERTSTATUS, 80d2i_OCSP_CRLID, 81d2i_OCSP_ONEREQ, 82d2i_OCSP_REQINFO, 83d2i_OCSP_REQUEST, 84d2i_OCSP_RESPBYTES, 85d2i_OCSP_RESPDATA, 86d2i_OCSP_RESPID, 87d2i_OCSP_RESPONSE, 88d2i_OCSP_REVOKEDINFO, 89d2i_OCSP_SERVICELOC, 90d2i_OCSP_SIGNATURE, 91d2i_OCSP_SINGLERESP, 92d2i_OSSL_ATTRIBUTE_DESCRIPTOR, 93d2i_OSSL_ATTRIBUTES_SYNTAX, 94d2i_OSSL_AUTHORITY_ATTRIBUTE_ID_SYNTAX, 95d2i_OSSL_BASIC_ATTR_CONSTRAINTS, 96d2i_OSSL_CMP_ATAVS, 97d2i_OSSL_CMP_MSG, 98d2i_OSSL_CMP_PKIHEADER, 99d2i_OSSL_CMP_PKISI, 100d2i_OSSL_CRMF_CERTID, 101d2i_OSSL_CRMF_CERTTEMPLATE, 102d2i_OSSL_CRMF_ENCRYPTEDVALUE, 103d2i_OSSL_CRMF_MSG, 104d2i_OSSL_CRMF_MSGS, 105d2i_OSSL_CRMF_PBMPARAMETER, 106d2i_OSSL_CRMF_PKIPUBLICATIONINFO, 107d2i_OSSL_CRMF_SINGLEPUBINFO, 108d2i_OSSL_HASH, 109d2i_OSSL_IETF_ATTR_SYNTAX, 110d2i_OSSL_INFO_SYNTAX, 111d2i_OSSL_INFO_SYNTAX_POINTER, 112d2i_OSSL_ISSUER_SERIAL, 113d2i_OSSL_OBJECT_DIGEST_INFO, 114d2i_OSSL_PRIVILEGE_POLICY_ID, 115d2i_OSSL_ROLE_SPEC_CERT_ID, 116d2i_OSSL_ROLE_SPEC_CERT_ID_SYNTAX, 117d2i_OSSL_TARGET_CERT, 118d2i_OSSL_TARGET, 119d2i_OSSL_TARGETING_INFORMATION, 120d2i_OSSL_TARGETS, 121d2i_OSSL_USER_NOTICE_SYNTAX, 122d2i_OTHERNAME, 123d2i_PBE2PARAM, 124d2i_PBEPARAM, 125d2i_PBKDF2PARAM, 126d2i_PBMAC1PARAM, 127d2i_PKCS12, 128d2i_PKCS12_BAGS, 129d2i_PKCS12_MAC_DATA, 130d2i_PKCS12_SAFEBAG, 131d2i_PKCS12_bio, 132d2i_PKCS12_fp, 133d2i_PKCS7, 134d2i_PKCS7_DIGEST, 135d2i_PKCS7_ENCRYPT, 136d2i_PKCS7_ENC_CONTENT, 137d2i_PKCS7_ENVELOPE, 138d2i_PKCS7_ISSUER_AND_SERIAL, 139d2i_PKCS7_RECIP_INFO, 140d2i_PKCS7_SIGNED, 141d2i_PKCS7_SIGNER_INFO, 142d2i_PKCS7_SIGN_ENVELOPE, 143d2i_PKCS7_bio, 144d2i_PKCS7_fp, 145d2i_PKCS8_PRIV_KEY_INFO, 146d2i_PKCS8_PRIV_KEY_INFO_bio, 147d2i_PKCS8_PRIV_KEY_INFO_fp, 148d2i_PKCS8_bio, 149d2i_PKCS8_fp, 150d2i_PKEY_USAGE_PERIOD, 151d2i_POLICYINFO, 152d2i_POLICYQUALINFO, 153d2i_PROFESSION_INFO, 154d2i_PROXY_CERT_INFO_EXTENSION, 155d2i_PROXY_POLICY, 156d2i_RSA_OAEP_PARAMS, 157d2i_RSA_PSS_PARAMS, 158d2i_SCRYPT_PARAMS, 159d2i_SCT_LIST, 160d2i_SXNET, 161d2i_SXNETID, 162d2i_TS_ACCURACY, 163d2i_TS_MSG_IMPRINT, 164d2i_TS_MSG_IMPRINT_bio, 165d2i_TS_MSG_IMPRINT_fp, 166d2i_TS_REQ, 167d2i_TS_REQ_bio, 168d2i_TS_REQ_fp, 169d2i_TS_RESP, 170d2i_TS_RESP_bio, 171d2i_TS_RESP_fp, 172d2i_TS_STATUS_INFO, 173d2i_TS_TST_INFO, 174d2i_TS_TST_INFO_bio, 175d2i_TS_TST_INFO_fp, 176d2i_USERNOTICE, 177d2i_X509, 178d2i_X509_bio, 179d2i_X509_fp, 180d2i_X509_ACERT, 181d2i_X509_ACERT_bio, 182d2i_X509_ACERT_fp, 183d2i_X509_ALGOR, 184d2i_X509_ALGORS, 185d2i_X509_ATTRIBUTE, 186d2i_X509_CERT_AUX, 187d2i_X509_CINF, 188d2i_X509_CRL, 189d2i_X509_CRL_INFO, 190d2i_X509_CRL_bio, 191d2i_X509_CRL_fp, 192d2i_X509_EXTENSION, 193d2i_X509_EXTENSIONS, 194d2i_X509_NAME, 195d2i_X509_NAME_ENTRY, 196d2i_X509_PUBKEY, 197d2i_X509_PUBKEY_bio, 198d2i_X509_PUBKEY_fp, 199d2i_X509_REQ, 200d2i_X509_REQ_INFO, 201d2i_X509_REQ_bio, 202d2i_X509_REQ_fp, 203d2i_X509_REVOKED, 204d2i_X509_SIG, 205d2i_X509_VAL, 206i2d_ACCESS_DESCRIPTION, 207i2d_ADMISSIONS, 208i2d_ADMISSION_SYNTAX, 209i2d_ASIdOrRange, 210i2d_ASIdentifierChoice, 211i2d_ASIdentifiers, 212i2d_ASN1_BIT_STRING, 213i2d_ASN1_BMPSTRING, 214i2d_ASN1_ENUMERATED, 215i2d_ASN1_GENERALIZEDTIME, 216i2d_ASN1_GENERALSTRING, 217i2d_ASN1_IA5STRING, 218i2d_ASN1_INTEGER, 219i2d_ASN1_NULL, 220i2d_ASN1_OBJECT, 221i2d_ASN1_OCTET_STRING, 222i2d_ASN1_PRINTABLE, 223i2d_ASN1_PRINTABLESTRING, 224i2d_ASN1_SEQUENCE_ANY, 225i2d_ASN1_SET_ANY, 226i2d_ASN1_T61STRING, 227i2d_ASN1_TIME, 228i2d_ASN1_TYPE, 229i2d_ASN1_UNIVERSALSTRING, 230i2d_ASN1_UTCTIME, 231i2d_ASN1_UTF8STRING, 232i2d_ASN1_VISIBLESTRING, 233i2d_ASN1_bio_stream, 234i2d_ASRange, 235i2d_AUTHORITY_INFO_ACCESS, 236i2d_AUTHORITY_KEYID, 237i2d_BASIC_CONSTRAINTS, 238i2d_CERTIFICATEPOLICIES, 239i2d_CMS_ContentInfo, 240i2d_CMS_ReceiptRequest, 241i2d_CMS_bio, 242i2d_CRL_DIST_POINTS, 243i2d_DHxparams, 244i2d_DIRECTORYSTRING, 245i2d_DISPLAYTEXT, 246i2d_DIST_POINT, 247i2d_DIST_POINT_NAME, 248i2d_DSA_SIG, 249i2d_ECDSA_SIG, 250i2d_ECPKParameters, 251i2d_EDIPARTYNAME, 252i2d_ESS_CERT_ID, 253i2d_ESS_CERT_ID_V2, 254i2d_ESS_ISSUER_SERIAL, 255i2d_ESS_SIGNING_CERT, 256i2d_ESS_SIGNING_CERT_V2, 257i2d_EXTENDED_KEY_USAGE, 258i2d_GENERAL_NAME, 259i2d_GENERAL_NAMES, 260i2d_IPAddressChoice, 261i2d_IPAddressFamily, 262i2d_IPAddressOrRange, 263i2d_IPAddressRange, 264i2d_ISSUER_SIGN_TOOL, 265i2d_ISSUING_DIST_POINT, 266i2d_NAMING_AUTHORITY, 267i2d_NETSCAPE_CERT_SEQUENCE, 268i2d_NETSCAPE_SPKAC, 269i2d_NETSCAPE_SPKI, 270i2d_NOTICEREF, 271i2d_OCSP_BASICRESP, 272i2d_OCSP_CERTID, 273i2d_OCSP_CERTSTATUS, 274i2d_OCSP_CRLID, 275i2d_OCSP_ONEREQ, 276i2d_OCSP_REQINFO, 277i2d_OCSP_REQUEST, 278i2d_OCSP_RESPBYTES, 279i2d_OCSP_RESPDATA, 280i2d_OCSP_RESPID, 281i2d_OCSP_RESPONSE, 282i2d_OCSP_REVOKEDINFO, 283i2d_OCSP_SERVICELOC, 284i2d_OCSP_SIGNATURE, 285i2d_OCSP_SINGLERESP, 286i2d_OSSL_ATTRIBUTE_DESCRIPTOR, 287i2d_OSSL_ATTRIBUTES_SYNTAX, 288i2d_OSSL_AUTHORITY_ATTRIBUTE_ID_SYNTAX, 289i2d_OSSL_BASIC_ATTR_CONSTRAINTS, 290i2d_OSSL_CMP_ATAVS, 291i2d_OSSL_CMP_MSG, 292i2d_OSSL_CMP_PKIHEADER, 293i2d_OSSL_CMP_PKISI, 294i2d_OSSL_CRMF_CERTID, 295i2d_OSSL_CRMF_CERTTEMPLATE, 296i2d_OSSL_CRMF_ENCRYPTEDVALUE, 297i2d_OSSL_CRMF_MSG, 298i2d_OSSL_CRMF_MSGS, 299i2d_OSSL_CRMF_PBMPARAMETER, 300i2d_OSSL_CRMF_PKIPUBLICATIONINFO, 301i2d_OSSL_CRMF_SINGLEPUBINFO, 302i2d_OSSL_HASH, 303i2d_OSSL_IETF_ATTR_SYNTAX, 304i2d_OSSL_INFO_SYNTAX, 305i2d_OSSL_INFO_SYNTAX_POINTER, 306i2d_OSSL_ISSUER_SERIAL, 307i2d_OSSL_OBJECT_DIGEST_INFO, 308i2d_OSSL_PRIVILEGE_POLICY_ID, 309i2d_OSSL_ROLE_SPEC_CERT_ID, 310i2d_OSSL_ROLE_SPEC_CERT_ID_SYNTAX, 311i2d_OSSL_TARGET_CERT, 312i2d_OSSL_TARGET, 313i2d_OSSL_TARGETING_INFORMATION, 314i2d_OSSL_TARGETS, 315i2d_OSSL_USER_NOTICE_SYNTAX, 316i2d_OTHERNAME, 317i2d_PBE2PARAM, 318i2d_PBEPARAM, 319i2d_PBKDF2PARAM, 320i2d_PBMAC1PARAM, 321i2d_PKCS12, 322i2d_PKCS12_BAGS, 323i2d_PKCS12_MAC_DATA, 324i2d_PKCS12_SAFEBAG, 325i2d_PKCS12_bio, 326i2d_PKCS12_fp, 327i2d_PKCS7, 328i2d_PKCS7_DIGEST, 329i2d_PKCS7_ENCRYPT, 330i2d_PKCS7_ENC_CONTENT, 331i2d_PKCS7_ENVELOPE, 332i2d_PKCS7_ISSUER_AND_SERIAL, 333i2d_PKCS7_NDEF, 334i2d_PKCS7_RECIP_INFO, 335i2d_PKCS7_SIGNED, 336i2d_PKCS7_SIGNER_INFO, 337i2d_PKCS7_SIGN_ENVELOPE, 338i2d_PKCS7_bio, 339i2d_PKCS7_fp, 340i2d_PKCS8PrivateKeyInfo_bio, 341i2d_PKCS8PrivateKeyInfo_fp, 342i2d_PKCS8_PRIV_KEY_INFO, 343i2d_PKCS8_PRIV_KEY_INFO_bio, 344i2d_PKCS8_PRIV_KEY_INFO_fp, 345i2d_PKCS8_bio, 346i2d_PKCS8_fp, 347i2d_PKEY_USAGE_PERIOD, 348i2d_POLICYINFO, 349i2d_POLICYQUALINFO, 350i2d_PROFESSION_INFO, 351i2d_PROXY_CERT_INFO_EXTENSION, 352i2d_PROXY_POLICY, 353i2d_RSA_OAEP_PARAMS, 354i2d_RSA_PSS_PARAMS, 355i2d_SCRYPT_PARAMS, 356i2d_SCT_LIST, 357i2d_SXNET, 358i2d_SXNETID, 359i2d_TS_ACCURACY, 360i2d_TS_MSG_IMPRINT, 361i2d_TS_MSG_IMPRINT_bio, 362i2d_TS_MSG_IMPRINT_fp, 363i2d_TS_REQ, 364i2d_TS_REQ_bio, 365i2d_TS_REQ_fp, 366i2d_TS_RESP, 367i2d_TS_RESP_bio, 368i2d_TS_RESP_fp, 369i2d_TS_STATUS_INFO, 370i2d_TS_TST_INFO, 371i2d_TS_TST_INFO_bio, 372i2d_TS_TST_INFO_fp, 373i2d_USERNOTICE, 374i2d_X509, 375i2d_X509_bio, 376i2d_X509_fp, 377i2d_X509_ACERT, 378i2d_X509_ACERT_bio, 379i2d_X509_ACERT_fp, 380i2d_X509_ALGOR, 381i2d_X509_ALGORS, 382i2d_X509_ATTRIBUTE, 383i2d_X509_CERT_AUX, 384i2d_X509_CINF, 385i2d_X509_CRL, 386i2d_X509_CRL_INFO, 387i2d_X509_CRL_bio, 388i2d_X509_CRL_fp, 389i2d_X509_EXTENSION, 390i2d_X509_EXTENSIONS, 391i2d_X509_NAME, 392i2d_X509_NAME_ENTRY, 393i2d_X509_PUBKEY, 394i2d_X509_PUBKEY_bio, 395i2d_X509_PUBKEY_fp, 396i2d_X509_REQ, 397i2d_X509_REQ_INFO, 398i2d_X509_REQ_bio, 399i2d_X509_REQ_fp, 400i2d_X509_REVOKED, 401i2d_X509_SIG, 402i2d_X509_VAL, 403- convert objects from/to ASN.1/DER representation 404 405=head1 SYNOPSIS 406 407=for openssl generic 408 409 TYPE *d2i_TYPE(TYPE **a, const unsigned char **ppin, long length); 410 TYPE *d2i_TYPE_bio(BIO *bp, TYPE **a); 411 TYPE *d2i_TYPE_fp(FILE *fp, TYPE **a); 412 413 int i2d_TYPE(const TYPE *a, unsigned char **ppout); 414 int i2d_TYPE(TYPE *a, unsigned char **ppout); 415 int i2d_TYPE_fp(FILE *fp, const TYPE *a); 416 int i2d_TYPE_fp(FILE *fp, TYPE *a); 417 int i2d_TYPE_bio(BIO *bp, const TYPE *a); 418 int i2d_TYPE_bio(BIO *bp, TYPE *a); 419 420=head1 DESCRIPTION 421 422In the description here, B<I<TYPE>> is used a placeholder 423for any of the OpenSSL datatypes, such as B<X509_CRL>. 424The function parameters I<ppin> and I<ppout> are generally 425either both named I<pp> in the headers, or I<in> and I<out>. 426 427These functions convert OpenSSL objects to and from their ASN.1/DER 428encoding. Unlike the C structures which can have pointers to sub-objects 429within, the DER is a serialized encoding, suitable for sending over the 430network, writing to a file, and so on. 431 432B<d2i_I<TYPE>>() attempts to decode I<len> bytes at I<*ppin>. If successful a 433pointer to the B<I<TYPE>> structure is returned and I<*ppin> is incremented to 434the byte following the parsed data. If I<a> is not NULL then a pointer 435to the returned structure is also written to I<*a>. If an error occurred 436then NULL is returned. The caller retains ownership of the 437returned object and needs to free it when it is no longer needed, e.g. 438using X509_free() for X509 objects or DSA_SIG_free() for DSA_SIG objects. 439 440On a successful return, if I<*a> is not NULL then it is assumed that I<*a> 441contains a valid B<I<TYPE>> structure and an attempt is made to reuse it. 442For B<I<TYPE>> structures where it matters it is possible to set up a library 443context on the decoded structure this way (see the B<EXAMPLES> section). 444However using the "reuse" capability for other purposes is B<strongly 445discouraged> (see B<BUGS> below, and the discussion in the B<RETURN VALUES> 446section). 447 448B<d2i_I<TYPE>_bio>() is similar to B<d2i_I<TYPE>>() except it attempts 449to parse data from BIO I<bp>. 450 451B<d2i_I<TYPE>_fp>() is similar to B<d2i_I<TYPE>>() except it attempts 452to parse data from FILE pointer I<fp>. 453 454B<i2d_I<TYPE>>() encodes the structure pointed to by I<a> into DER format. 455If I<ppout> is not NULL, it writes the DER encoded data to the buffer 456at I<*ppout>, and increments it to point after the data just written. 457If the return value is negative an error occurred, otherwise it 458returns the length of the encoded data. 459 460If I<*ppout> is NULL memory will be allocated for a buffer and the encoded 461data written to it. In this case I<*ppout> is not incremented and it points 462to the start of the data just written. 463 464B<i2d_I<TYPE>_bio>() is similar to B<i2d_I<TYPE>>() except it writes 465the encoding of the structure I<a> to BIO I<bp> and it 466returns 1 for success and 0 for failure. 467 468B<i2d_I<TYPE>_fp>() is similar to B<i2d_I<TYPE>>() except it writes 469the encoding of the structure I<a> to FILE pointer I<fp> and it 470returns 1 for success and 0 for failure. 471 472These routines do not encrypt private keys and therefore offer no 473security; use L<PEM_write_PrivateKey(3)> or similar for writing to files. 474 475=head1 NOTES 476 477The letters B<i> and B<d> in B<i2d_I<TYPE>>() stand for 478"internal" (that is, an internal C structure) and "DER" respectively. 479So B<i2d_I<TYPE>>() converts from internal to DER. 480 481The functions can also understand B<BER> forms. 482 483The actual TYPE structure passed to B<i2d_I<TYPE>>() must be a valid 484populated B<I<TYPE>> structure -- it B<cannot> simply be fed with an 485empty structure such as that returned by TYPE_new(). 486 487The encoded data is in binary form and may contain embedded zeros. 488Therefore, any FILE pointers or BIOs should be opened in binary mode. 489Functions such as strlen() will B<not> return the correct length 490of the encoded structure. 491 492The ways that I<*ppin> and I<*ppout> are incremented after the operation 493can trap the unwary. See the B<WARNINGS> section for some common 494errors. 495The reason for this-auto increment behaviour is to reflect a typical 496usage of ASN1 functions: after one structure is encoded or decoded 497another will be processed after it. 498 499The following points about the data types might be useful: 500 501=over 4 502 503=item B<ASN1_OBJECT> 504 505Represents an ASN1 OBJECT IDENTIFIER. 506 507=item B<DHparams> 508 509Represents a PKCS#3 DH parameters structure. 510 511=item B<DHxparams> 512 513Represents an ANSI X9.42 DH parameters structure. 514 515=item B<ECDSA_SIG> 516 517Represents an ECDSA signature. 518 519=item B<X509_ALGOR> 520 521Represents an B<AlgorithmIdentifier> structure as used in IETF RFC 6960 and 522elsewhere. 523 524=item B<X509_NAME> 525 526Represents a B<Name> type as used for subject and issuer names in 527IETF RFC 6960 and elsewhere. 528 529=item B<X509_REQ> 530 531Represents a PKCS#10 certificate request. 532 533=item B<X509_SIG> 534 535Represents the B<DigestInfo> structure defined in PKCS#1 and PKCS#7. 536 537=back 538 539=head1 RETURN VALUES 540 541B<d2i_I<TYPE>>(), B<d2i_I<TYPE>_bio>() and B<d2i_I<TYPE>_fp>() return a valid 542B<I<TYPE>> structure or NULL if an error occurs. If the "reuse" capability has 543been used with a valid structure being passed in via I<a>, then the object is 544freed in the event of error and I<*a> is set to NULL. 545 546B<i2d_I<TYPE>>() returns the number of bytes successfully encoded or a negative 547value if an error occurs. 548 549B<i2d_I<TYPE>_bio>() and B<i2d_I<TYPE>_fp>() return 1 for success and 0 if an 550error occurs. 551 552=head1 EXAMPLES 553 554Allocate and encode the DER encoding of an X509 structure: 555 556 int len; 557 unsigned char *buf; 558 559 buf = NULL; 560 len = i2d_X509(x, &buf); 561 if (len < 0) 562 /* error */ 563 564Attempt to decode a buffer: 565 566 X509 *x; 567 unsigned char *buf; 568 const unsigned char *p; 569 int len; 570 571 /* Set up buf and len to point to the input buffer. */ 572 p = buf; 573 x = d2i_X509(NULL, &p, len); 574 if (x == NULL) 575 /* error */ 576 577Alternative technique: 578 579 X509 *x; 580 unsigned char *buf; 581 const unsigned char *p; 582 int len; 583 584 /* Set up buf and len to point to the input buffer. */ 585 p = buf; 586 x = NULL; 587 588 if (d2i_X509(&x, &p, len) == NULL) 589 /* error */ 590 591Setting up a library context and property query: 592 593 X509 *x; 594 unsigned char *buf; 595 const unsigned char *p; 596 int len; 597 OSSL_LIB_CTX *libctx = ....; 598 const char *propq = ....; 599 600 /* Set up buf and len to point to the input buffer. */ 601 p = buf; 602 x = X509_new_ex(libctx, propq); 603 604 if (d2i_X509(&x, &p, len) == NULL) 605 /* error, x was freed and NULL assigned to it (see RETURN VALUES) */ 606 607=head1 WARNINGS 608 609Using a temporary variable is mandatory. A common 610mistake is to attempt to use a buffer directly as follows: 611 612 int len; 613 unsigned char *buf; 614 615 len = i2d_X509(x, NULL); 616 buf = OPENSSL_malloc(len); 617 ... 618 i2d_X509(x, &buf); 619 ... 620 OPENSSL_free(buf); 621 622This code will result in I<buf> apparently containing garbage because 623it was incremented after the call to point after the data just written. 624Also I<buf> will no longer contain the pointer allocated by OPENSSL_malloc() 625and the subsequent call to OPENSSL_free() is likely to crash. 626 627Another trap to avoid is misuse of the I<a> argument to B<d2i_I<TYPE>>(): 628 629 X509 *x; 630 631 if (d2i_X509(&x, &p, len) == NULL) 632 /* error */ 633 634This will probably crash somewhere in d2i_X509(). The reason for this 635is that the variable I<x> is uninitialized and an attempt will be made to 636interpret its (invalid) value as an B<X509> structure, typically causing 637a segmentation violation. If I<x> is set to NULL first then this will not 638happen. 639 640=head1 BUGS 641 642In some versions of OpenSSL the "reuse" behaviour of B<d2i_I<TYPE>>() when 643I<*a> is valid is broken and some parts of the reused structure may 644persist if they are not present in the new one. Additionally, in versions of 645OpenSSL prior to 1.1.0, when the "reuse" behaviour is used and an error occurs 646the behaviour is inconsistent. Some functions behaved as described here, while 647some did not free I<*a> on error and did not set I<*a> to NULL. 648 649As a result of the above issues the "reuse" behaviour is strongly discouraged. 650 651B<i2d_I<TYPE>>() will not return an error in many versions of OpenSSL, 652if mandatory fields are not initialized due to a programming error 653then the encoded structure may contain invalid data or omit the 654fields entirely and will not be parsed by B<d2i_I<TYPE>>(). This may be 655fixed in future so code should not assume that B<i2d_I<TYPE>>() will 656always succeed. 657 658Any function which encodes a structure (B<i2d_I<TYPE>>(), 659B<i2d_I<TYPE>_bio>() or B<i2d_I<TYPE>_fp>()) may return a stale encoding if the 660structure has been modified after deserialization or previous 661serialization. This is because some objects cache the encoding for 662efficiency reasons. 663 664=head1 COPYRIGHT 665 666Copyright 1998-2024 The OpenSSL Project Authors. All Rights Reserved. 667 668Licensed under the Apache License 2.0 (the "License"). You may not use 669this file except in compliance with the License. You can obtain a copy 670in the file LICENSE in the source distribution or at 671L<https://www.openssl.org/source/license.html>. 672 673=cut 674
