d2i_X509.pod 14 KB

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  1. =pod
  2. =head1 NAME
  3. d2i_ACCESS_DESCRIPTION,
  4. d2i_ADMISSIONS,
  5. d2i_ADMISSION_SYNTAX,
  6. d2i_ASIdOrRange,
  7. d2i_ASIdentifierChoice,
  8. d2i_ASIdentifiers,
  9. d2i_ASN1_BIT_STRING,
  10. d2i_ASN1_BMPSTRING,
  11. d2i_ASN1_ENUMERATED,
  12. d2i_ASN1_GENERALIZEDTIME,
  13. d2i_ASN1_GENERALSTRING,
  14. d2i_ASN1_IA5STRING,
  15. d2i_ASN1_INTEGER,
  16. d2i_ASN1_NULL,
  17. d2i_ASN1_OBJECT,
  18. d2i_ASN1_OCTET_STRING,
  19. d2i_ASN1_PRINTABLE,
  20. d2i_ASN1_PRINTABLESTRING,
  21. d2i_ASN1_SEQUENCE_ANY,
  22. d2i_ASN1_SET_ANY,
  23. d2i_ASN1_T61STRING,
  24. d2i_ASN1_TIME,
  25. d2i_ASN1_TYPE,
  26. d2i_ASN1_UINTEGER,
  27. d2i_ASN1_UNIVERSALSTRING,
  28. d2i_ASN1_UTCTIME,
  29. d2i_ASN1_UTF8STRING,
  30. d2i_ASN1_VISIBLESTRING,
  31. d2i_ASRange,
  32. d2i_AUTHORITY_INFO_ACCESS,
  33. d2i_AUTHORITY_KEYID,
  34. d2i_BASIC_CONSTRAINTS,
  35. d2i_CERTIFICATEPOLICIES,
  36. d2i_CMS_ContentInfo,
  37. d2i_CMS_ReceiptRequest,
  38. d2i_CMS_bio,
  39. d2i_CRL_DIST_POINTS,
  40. d2i_DHxparams,
  41. d2i_DIRECTORYSTRING,
  42. d2i_DISPLAYTEXT,
  43. d2i_DIST_POINT,
  44. d2i_DIST_POINT_NAME,
  45. d2i_DSAPrivateKey,
  46. d2i_DSAPrivateKey_bio,
  47. d2i_DSAPrivateKey_fp,
  48. d2i_DSAPublicKey,
  49. d2i_DSA_PUBKEY,
  50. d2i_DSA_PUBKEY_bio,
  51. d2i_DSA_PUBKEY_fp,
  52. d2i_DSA_SIG,
  53. d2i_DSAparams,
  54. d2i_ECPKParameters,
  55. d2i_ECParameters,
  56. d2i_ECPrivateKey,
  57. d2i_ECPrivateKey_bio,
  58. d2i_ECPrivateKey_fp,
  59. d2i_EC_PUBKEY,
  60. d2i_EC_PUBKEY_bio,
  61. d2i_EC_PUBKEY_fp,
  62. d2i_EDIPARTYNAME,
  63. d2i_ESS_CERT_ID,
  64. d2i_ESS_ISSUER_SERIAL,
  65. d2i_ESS_SIGNING_CERT,
  66. d2i_EXTENDED_KEY_USAGE,
  67. d2i_GENERAL_NAME,
  68. d2i_GENERAL_NAMES,
  69. d2i_IPAddressChoice,
  70. d2i_IPAddressFamily,
  71. d2i_IPAddressOrRange,
  72. d2i_IPAddressRange,
  73. d2i_ISSUING_DIST_POINT,
  74. d2i_NAMING_AUTHORITY,
  75. d2i_NETSCAPE_CERT_SEQUENCE,
  76. d2i_NETSCAPE_SPKAC,
  77. d2i_NETSCAPE_SPKI,
  78. d2i_NOTICEREF,
  79. d2i_OCSP_BASICRESP,
  80. d2i_OCSP_CERTID,
  81. d2i_OCSP_CERTSTATUS,
  82. d2i_OCSP_CRLID,
  83. d2i_OCSP_ONEREQ,
  84. d2i_OCSP_REQINFO,
  85. d2i_OCSP_REQUEST,
  86. d2i_OCSP_RESPBYTES,
  87. d2i_OCSP_RESPDATA,
  88. d2i_OCSP_RESPID,
  89. d2i_OCSP_RESPONSE,
  90. d2i_OCSP_REVOKEDINFO,
  91. d2i_OCSP_SERVICELOC,
  92. d2i_OCSP_SIGNATURE,
  93. d2i_OCSP_SINGLERESP,
  94. d2i_OTHERNAME,
  95. d2i_PBE2PARAM,
  96. d2i_PBEPARAM,
  97. d2i_PBKDF2PARAM,
  98. d2i_PKCS12,
  99. d2i_PKCS12_BAGS,
  100. d2i_PKCS12_MAC_DATA,
  101. d2i_PKCS12_SAFEBAG,
  102. d2i_PKCS12_bio,
  103. d2i_PKCS12_fp,
  104. d2i_PKCS7,
  105. d2i_PKCS7_DIGEST,
  106. d2i_PKCS7_ENCRYPT,
  107. d2i_PKCS7_ENC_CONTENT,
  108. d2i_PKCS7_ENVELOPE,
  109. d2i_PKCS7_ISSUER_AND_SERIAL,
  110. d2i_PKCS7_RECIP_INFO,
  111. d2i_PKCS7_SIGNED,
  112. d2i_PKCS7_SIGNER_INFO,
  113. d2i_PKCS7_SIGN_ENVELOPE,
  114. d2i_PKCS7_bio,
  115. d2i_PKCS7_fp,
  116. d2i_PKCS8_PRIV_KEY_INFO,
  117. d2i_PKCS8_PRIV_KEY_INFO_bio,
  118. d2i_PKCS8_PRIV_KEY_INFO_fp,
  119. d2i_PKCS8_bio,
  120. d2i_PKCS8_fp,
  121. d2i_PKEY_USAGE_PERIOD,
  122. d2i_POLICYINFO,
  123. d2i_POLICYQUALINFO,
  124. d2i_PROFESSION_INFO,
  125. d2i_PROXY_CERT_INFO_EXTENSION,
  126. d2i_PROXY_POLICY,
  127. d2i_RSAPrivateKey,
  128. d2i_RSAPrivateKey_bio,
  129. d2i_RSAPrivateKey_fp,
  130. d2i_RSAPublicKey,
  131. d2i_RSAPublicKey_bio,
  132. d2i_RSAPublicKey_fp,
  133. d2i_RSA_OAEP_PARAMS,
  134. d2i_RSA_PSS_PARAMS,
  135. d2i_RSA_PUBKEY,
  136. d2i_RSA_PUBKEY_bio,
  137. d2i_RSA_PUBKEY_fp,
  138. d2i_SCRYPT_PARAMS,
  139. d2i_SCT_LIST,
  140. d2i_SXNET,
  141. d2i_SXNETID,
  142. d2i_TS_ACCURACY,
  143. d2i_TS_MSG_IMPRINT,
  144. d2i_TS_MSG_IMPRINT_bio,
  145. d2i_TS_MSG_IMPRINT_fp,
  146. d2i_TS_REQ,
  147. d2i_TS_REQ_bio,
  148. d2i_TS_REQ_fp,
  149. d2i_TS_RESP,
  150. d2i_TS_RESP_bio,
  151. d2i_TS_RESP_fp,
  152. d2i_TS_STATUS_INFO,
  153. d2i_TS_TST_INFO,
  154. d2i_TS_TST_INFO_bio,
  155. d2i_TS_TST_INFO_fp,
  156. d2i_USERNOTICE,
  157. d2i_X509,
  158. d2i_X509_ALGOR,
  159. d2i_X509_ALGORS,
  160. d2i_X509_ATTRIBUTE,
  161. d2i_X509_CERT_AUX,
  162. d2i_X509_CINF,
  163. d2i_X509_CRL,
  164. d2i_X509_CRL_INFO,
  165. d2i_X509_CRL_bio,
  166. d2i_X509_CRL_fp,
  167. d2i_X509_EXTENSION,
  168. d2i_X509_EXTENSIONS,
  169. d2i_X509_NAME,
  170. d2i_X509_NAME_ENTRY,
  171. d2i_X509_PUBKEY,
  172. d2i_X509_REQ,
  173. d2i_X509_REQ_INFO,
  174. d2i_X509_REQ_bio,
  175. d2i_X509_REQ_fp,
  176. d2i_X509_REVOKED,
  177. d2i_X509_SIG,
  178. d2i_X509_VAL,
  179. i2d_ACCESS_DESCRIPTION,
  180. i2d_ADMISSIONS,
  181. i2d_ADMISSION_SYNTAX,
  182. i2d_ASIdOrRange,
  183. i2d_ASIdentifierChoice,
  184. i2d_ASIdentifiers,
  185. i2d_ASN1_BIT_STRING,
  186. i2d_ASN1_BMPSTRING,
  187. i2d_ASN1_ENUMERATED,
  188. i2d_ASN1_GENERALIZEDTIME,
  189. i2d_ASN1_GENERALSTRING,
  190. i2d_ASN1_IA5STRING,
  191. i2d_ASN1_INTEGER,
  192. i2d_ASN1_NULL,
  193. i2d_ASN1_OBJECT,
  194. i2d_ASN1_OCTET_STRING,
  195. i2d_ASN1_PRINTABLE,
  196. i2d_ASN1_PRINTABLESTRING,
  197. i2d_ASN1_SEQUENCE_ANY,
  198. i2d_ASN1_SET_ANY,
  199. i2d_ASN1_T61STRING,
  200. i2d_ASN1_TIME,
  201. i2d_ASN1_TYPE,
  202. i2d_ASN1_UNIVERSALSTRING,
  203. i2d_ASN1_UTCTIME,
  204. i2d_ASN1_UTF8STRING,
  205. i2d_ASN1_VISIBLESTRING,
  206. i2d_ASN1_bio_stream,
  207. i2d_ASRange,
  208. i2d_AUTHORITY_INFO_ACCESS,
  209. i2d_AUTHORITY_KEYID,
  210. i2d_BASIC_CONSTRAINTS,
  211. i2d_CERTIFICATEPOLICIES,
  212. i2d_CMS_ContentInfo,
  213. i2d_CMS_ReceiptRequest,
  214. i2d_CMS_bio,
  215. i2d_CRL_DIST_POINTS,
  216. i2d_DHxparams,
  217. i2d_DIRECTORYSTRING,
  218. i2d_DISPLAYTEXT,
  219. i2d_DIST_POINT,
  220. i2d_DIST_POINT_NAME,
  221. i2d_DSAPrivateKey,
  222. i2d_DSAPrivateKey_bio,
  223. i2d_DSAPrivateKey_fp,
  224. i2d_DSAPublicKey,
  225. i2d_DSA_PUBKEY,
  226. i2d_DSA_PUBKEY_bio,
  227. i2d_DSA_PUBKEY_fp,
  228. i2d_DSA_SIG,
  229. i2d_DSAparams,
  230. i2d_ECPKParameters,
  231. i2d_ECParameters,
  232. i2d_ECPrivateKey,
  233. i2d_ECPrivateKey_bio,
  234. i2d_ECPrivateKey_fp,
  235. i2d_EC_PUBKEY,
  236. i2d_EC_PUBKEY_bio,
  237. i2d_EC_PUBKEY_fp,
  238. i2d_EDIPARTYNAME,
  239. i2d_ESS_CERT_ID,
  240. i2d_ESS_ISSUER_SERIAL,
  241. i2d_ESS_SIGNING_CERT,
  242. i2d_EXTENDED_KEY_USAGE,
  243. i2d_GENERAL_NAME,
  244. i2d_GENERAL_NAMES,
  245. i2d_IPAddressChoice,
  246. i2d_IPAddressFamily,
  247. i2d_IPAddressOrRange,
  248. i2d_IPAddressRange,
  249. i2d_ISSUING_DIST_POINT,
  250. i2d_NAMING_AUTHORITY,
  251. i2d_NETSCAPE_CERT_SEQUENCE,
  252. i2d_NETSCAPE_SPKAC,
  253. i2d_NETSCAPE_SPKI,
  254. i2d_NOTICEREF,
  255. i2d_OCSP_BASICRESP,
  256. i2d_OCSP_CERTID,
  257. i2d_OCSP_CERTSTATUS,
  258. i2d_OCSP_CRLID,
  259. i2d_OCSP_ONEREQ,
  260. i2d_OCSP_REQINFO,
  261. i2d_OCSP_REQUEST,
  262. i2d_OCSP_RESPBYTES,
  263. i2d_OCSP_RESPDATA,
  264. i2d_OCSP_RESPID,
  265. i2d_OCSP_RESPONSE,
  266. i2d_OCSP_REVOKEDINFO,
  267. i2d_OCSP_SERVICELOC,
  268. i2d_OCSP_SIGNATURE,
  269. i2d_OCSP_SINGLERESP,
  270. i2d_OTHERNAME,
  271. i2d_PBE2PARAM,
  272. i2d_PBEPARAM,
  273. i2d_PBKDF2PARAM,
  274. i2d_PKCS12,
  275. i2d_PKCS12_BAGS,
  276. i2d_PKCS12_MAC_DATA,
  277. i2d_PKCS12_SAFEBAG,
  278. i2d_PKCS12_bio,
  279. i2d_PKCS12_fp,
  280. i2d_PKCS7,
  281. i2d_PKCS7_DIGEST,
  282. i2d_PKCS7_ENCRYPT,
  283. i2d_PKCS7_ENC_CONTENT,
  284. i2d_PKCS7_ENVELOPE,
  285. i2d_PKCS7_ISSUER_AND_SERIAL,
  286. i2d_PKCS7_NDEF,
  287. i2d_PKCS7_RECIP_INFO,
  288. i2d_PKCS7_SIGNED,
  289. i2d_PKCS7_SIGNER_INFO,
  290. i2d_PKCS7_SIGN_ENVELOPE,
  291. i2d_PKCS7_bio,
  292. i2d_PKCS7_fp,
  293. i2d_PKCS8PrivateKeyInfo_bio,
  294. i2d_PKCS8PrivateKeyInfo_fp,
  295. i2d_PKCS8_PRIV_KEY_INFO,
  296. i2d_PKCS8_PRIV_KEY_INFO_bio,
  297. i2d_PKCS8_PRIV_KEY_INFO_fp,
  298. i2d_PKCS8_bio,
  299. i2d_PKCS8_fp,
  300. i2d_PKEY_USAGE_PERIOD,
  301. i2d_POLICYINFO,
  302. i2d_POLICYQUALINFO,
  303. i2d_PROFESSION_INFO,
  304. i2d_PROXY_CERT_INFO_EXTENSION,
  305. i2d_PROXY_POLICY,
  306. i2d_PublicKey,
  307. i2d_RSAPrivateKey,
  308. i2d_RSAPrivateKey_bio,
  309. i2d_RSAPrivateKey_fp,
  310. i2d_RSAPublicKey,
  311. i2d_RSAPublicKey_bio,
  312. i2d_RSAPublicKey_fp,
  313. i2d_RSA_OAEP_PARAMS,
  314. i2d_RSA_PSS_PARAMS,
  315. i2d_RSA_PUBKEY,
  316. i2d_RSA_PUBKEY_bio,
  317. i2d_RSA_PUBKEY_fp,
  318. i2d_SCRYPT_PARAMS,
  319. i2d_SCT_LIST,
  320. i2d_SXNET,
  321. i2d_SXNETID,
  322. i2d_TS_ACCURACY,
  323. i2d_TS_MSG_IMPRINT,
  324. i2d_TS_MSG_IMPRINT_bio,
  325. i2d_TS_MSG_IMPRINT_fp,
  326. i2d_TS_REQ,
  327. i2d_TS_REQ_bio,
  328. i2d_TS_REQ_fp,
  329. i2d_TS_RESP,
  330. i2d_TS_RESP_bio,
  331. i2d_TS_RESP_fp,
  332. i2d_TS_STATUS_INFO,
  333. i2d_TS_TST_INFO,
  334. i2d_TS_TST_INFO_bio,
  335. i2d_TS_TST_INFO_fp,
  336. i2d_USERNOTICE,
  337. i2d_X509,
  338. i2d_X509_ALGOR,
  339. i2d_X509_ALGORS,
  340. i2d_X509_ATTRIBUTE,
  341. i2d_X509_CERT_AUX,
  342. i2d_X509_CINF,
  343. i2d_X509_CRL,
  344. i2d_X509_CRL_INFO,
  345. i2d_X509_CRL_bio,
  346. i2d_X509_CRL_fp,
  347. i2d_X509_EXTENSION,
  348. i2d_X509_EXTENSIONS,
  349. i2d_X509_NAME,
  350. i2d_X509_NAME_ENTRY,
  351. i2d_X509_PUBKEY,
  352. i2d_X509_REQ,
  353. i2d_X509_REQ_INFO,
  354. i2d_X509_REQ_bio,
  355. i2d_X509_REQ_fp,
  356. i2d_X509_REVOKED,
  357. i2d_X509_SIG,
  358. i2d_X509_VAL,
  359. - convert objects from/to ASN.1/DER representation
  360. =head1 SYNOPSIS
  361. =for comment generic
  362. TYPE *d2i_TYPE(TYPE **a, unsigned char **ppin, long length);
  363. TYPE *d2i_TYPE_bio(BIO *bp, TYPE **a);
  364. TYPE *d2i_TYPE_fp(FILE *fp, TYPE **a);
  365. int i2d_TYPE(TYPE *a, unsigned char **ppout);
  366. int i2d_TYPE_fp(FILE *fp, TYPE *a);
  367. int i2d_TYPE_bio(BIO *bp, TYPE *a);
  368. =head1 DESCRIPTION
  369. In the description here, I<TYPE> is used a placeholder
  370. for any of the OpenSSL datatypes, such as I<X509_CRL>.
  371. The function parameters I<ppin> and I<ppout> are generally
  372. either both named I<pp> in the headers, or I<in> and I<out>.
  373. These functions convert OpenSSL objects to and from their ASN.1/DER
  374. encoding. Unlike the C structures which can have pointers to sub-objects
  375. within, the DER is a serialized encoding, suitable for sending over the
  376. network, writing to a file, and so on.
  377. d2i_TYPE() attempts to decode B<len> bytes at B<*ppin>. If successful a
  378. pointer to the B<TYPE> structure is returned and B<*ppin> is incremented to
  379. the byte following the parsed data. If B<a> is not B<NULL> then a pointer
  380. to the returned structure is also written to B<*a>. If an error occurred
  381. then B<NULL> is returned.
  382. On a successful return, if B<*a> is not B<NULL> then it is assumed that B<*a>
  383. contains a valid B<TYPE> structure and an attempt is made to reuse it. This
  384. "reuse" capability is present for historical compatibility but its use is
  385. B<strongly discouraged> (see BUGS below, and the discussion in the RETURN
  386. VALUES section).
  387. d2i_TYPE_bio() is similar to d2i_TYPE() except it attempts
  388. to parse data from BIO B<bp>.
  389. d2i_TYPE_fp() is similar to d2i_TYPE() except it attempts
  390. to parse data from FILE pointer B<fp>.
  391. i2d_TYPE() encodes the structure pointed to by B<a> into DER format.
  392. If B<ppout> is not B<NULL>, it writes the DER encoded data to the buffer
  393. at B<*ppout>, and increments it to point after the data just written.
  394. If the return value is negative an error occurred, otherwise it
  395. returns the length of the encoded data.
  396. If B<*ppout> is B<NULL> memory will be allocated for a buffer and the encoded
  397. data written to it. In this case B<*ppout> is not incremented and it points
  398. to the start of the data just written.
  399. i2d_TYPE_bio() is similar to i2d_TYPE() except it writes
  400. the encoding of the structure B<a> to BIO B<bp> and it
  401. returns 1 for success and 0 for failure.
  402. i2d_TYPE_fp() is similar to i2d_TYPE() except it writes
  403. the encoding of the structure B<a> to BIO B<bp> and it
  404. returns 1 for success and 0 for failure.
  405. These routines do not encrypt private keys and therefore offer no
  406. security; use L<PEM_write_PrivateKey(3)> or similar for writing to files.
  407. =head1 NOTES
  408. The letters B<i> and B<d> in B<i2d_TYPE> stand for
  409. "internal" (that is, an internal C structure) and "DER" respectively.
  410. So B<i2d_TYPE> converts from internal to DER.
  411. The functions can also understand B<BER> forms.
  412. The actual TYPE structure passed to i2d_TYPE() must be a valid
  413. populated B<TYPE> structure -- it B<cannot> simply be fed with an
  414. empty structure such as that returned by TYPE_new().
  415. The encoded data is in binary form and may contain embedded zeroes.
  416. Therefore any FILE pointers or BIOs should be opened in binary mode.
  417. Functions such as strlen() will B<not> return the correct length
  418. of the encoded structure.
  419. The ways that B<*ppin> and B<*ppout> are incremented after the operation
  420. can trap the unwary. See the B<WARNINGS> section for some common
  421. errors.
  422. The reason for this-auto increment behaviour is to reflect a typical
  423. usage of ASN1 functions: after one structure is encoded or decoded
  424. another will be processed after it.
  425. The following points about the data types might be useful:
  426. =over 4
  427. =item B<ASN1_OBJECT>
  428. Represents an ASN1 OBJECT IDENTIFIER.
  429. =item B<DHparams>
  430. Represents a PKCS#3 DH parameters structure.
  431. =item B<DHparamx>
  432. Represents an ANSI X9.42 DH parameters structure.
  433. =item B<DSA_PUBKEY>
  434. Represents a DSA public key using a B<SubjectPublicKeyInfo> structure.
  435. =item B<DSAPublicKey, DSAPrivateKey>
  436. Use a non-standard OpenSSL format and should be avoided; use B<DSA_PUBKEY>,
  437. B<PEM_write_PrivateKey(3)>, or similar instead.
  438. =item B<RSAPublicKey>
  439. Represents a PKCS#1 RSA public key structure.
  440. =item B<X509_ALGOR>
  441. Represents an B<AlgorithmIdentifier> structure as used in IETF RFC 6960 and
  442. elsewhere.
  443. =item B<X509_Name>
  444. Represents a B<Name> type as used for subject and issuer names in
  445. IETF RFC 6960 and elsewhere.
  446. =item B<X509_REQ>
  447. Represents a PKCS#10 certificate request.
  448. =item B<X509_SIG>
  449. Represents the B<DigestInfo> structure defined in PKCS#1 and PKCS#7.
  450. =back
  451. =head1 EXAMPLES
  452. Allocate and encode the DER encoding of an X509 structure:
  453. int len;
  454. unsigned char *buf;
  455. buf = NULL;
  456. len = i2d_X509(x, &buf);
  457. if (len < 0)
  458. /* error */
  459. Attempt to decode a buffer:
  460. X509 *x;
  461. unsigned char *buf, *p;
  462. int len;
  463. /* Set up buf and len to point to the input buffer. */
  464. p = buf;
  465. x = d2i_X509(NULL, &p, len);
  466. if (x == NULL)
  467. /* error */
  468. Alternative technique:
  469. X509 *x;
  470. unsigned char *buf, *p;
  471. int len;
  472. /* Set up buf and len to point to the input buffer. */
  473. p = buf;
  474. x = NULL;
  475. if (d2i_X509(&x, &p, len) == NULL)
  476. /* error */
  477. =head1 WARNINGS
  478. Using a temporary variable is mandatory. A common
  479. mistake is to attempt to use a buffer directly as follows:
  480. int len;
  481. unsigned char *buf;
  482. len = i2d_X509(x, NULL);
  483. buf = OPENSSL_malloc(len);
  484. ...
  485. i2d_X509(x, &buf);
  486. ...
  487. OPENSSL_free(buf);
  488. This code will result in B<buf> apparently containing garbage because
  489. it was incremented after the call to point after the data just written.
  490. Also B<buf> will no longer contain the pointer allocated by OPENSSL_malloc()
  491. and the subsequent call to OPENSSL_free() is likely to crash.
  492. Another trap to avoid is misuse of the B<a> argument to d2i_TYPE():
  493. X509 *x;
  494. if (d2i_X509(&x, &p, len) == NULL)
  495. /* error */
  496. This will probably crash somewhere in d2i_X509(). The reason for this
  497. is that the variable B<x> is uninitialized and an attempt will be made to
  498. interpret its (invalid) value as an B<X509> structure, typically causing
  499. a segmentation violation. If B<x> is set to NULL first then this will not
  500. happen.
  501. =head1 BUGS
  502. In some versions of OpenSSL the "reuse" behaviour of d2i_TYPE() when
  503. B<*px> is valid is broken and some parts of the reused structure may
  504. persist if they are not present in the new one. As a result the use
  505. of this "reuse" behaviour is strongly discouraged.
  506. i2d_TYPE() will not return an error in many versions of OpenSSL,
  507. if mandatory fields are not initialized due to a programming error
  508. then the encoded structure may contain invalid data or omit the
  509. fields entirely and will not be parsed by d2i_TYPE(). This may be
  510. fixed in future so code should not assume that i2d_TYPE() will
  511. always succeed.
  512. Any function which encodes a structure (i2d_TYPE(),
  513. i2d_TYPE() or i2d_TYPE()) may return a stale encoding if the
  514. structure has been modified after deserialization or previous
  515. serialization. This is because some objects cache the encoding for
  516. efficiency reasons.
  517. =head1 RETURN VALUES
  518. d2i_TYPE(), d2i_TYPE_bio() and d2i_TYPE_fp() return a valid B<TYPE> structure
  519. or B<NULL> if an error occurs. If the "reuse" capability has been used with
  520. a valid structure being passed in via B<a>, then the object is not freed in
  521. the event of error but may be in a potentially invalid or inconsistent state.
  522. i2d_TYPE() returns the number of bytes successfully encoded or a negative
  523. value if an error occurs.
  524. i2d_TYPE_bio() and i2d_TYPE_fp() return 1 for success and 0 if an error
  525. occurs.
  526. =head1 COPYRIGHT
  527. Copyright 1998-2018 The OpenSSL Project Authors. All Rights Reserved.
  528. Licensed under the OpenSSL license (the "License"). You may not use
  529. this file except in compliance with the License. You can obtain a copy
  530. in the file LICENSE in the source distribution or at
  531. L<https://www.openssl.org/source/license.html>.
  532. =cut