BIO_f_base64.3ossl 7.2 KB

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  134. .\"
  135. .IX Title "BIO_F_BASE64 3ossl"
  136. .TH BIO_F_BASE64 3ossl "2024-09-03" "3.3.2" "OpenSSL"
  137. .\" For nroff, turn off justification. Always turn off hyphenation; it makes
  138. .\" way too many mistakes in technical documents.
  139. .if n .ad l
  140. .nh
  141. .SH "NAME"
  142. BIO_f_base64 \- base64 BIO filter
  143. .SH "SYNOPSIS"
  144. .IX Header "SYNOPSIS"
  145. .Vb 2
  146. \& #include <openssl/bio.h>
  147. \& #include <openssl/evp.h>
  148. \&
  149. \& const BIO_METHOD *BIO_f_base64(void);
  150. .Ve
  151. .SH "DESCRIPTION"
  152. .IX Header "DESCRIPTION"
  153. \&\fBBIO_f_base64()\fR returns the base64 \s-1BIO\s0 method. This is a filter
  154. \&\s-1BIO\s0 that base64 encodes any data written through it and decodes
  155. any data read through it.
  156. .PP
  157. Base64 BIOs do not support \fBBIO_gets()\fR or \fBBIO_puts()\fR.
  158. .PP
  159. For writing, by default output is divided to lines of length 64
  160. characters and there is a newline at the end of output.
  161. This behavior can be changed with \fB\s-1BIO_FLAGS_BASE64_NO_NL\s0\fR flag.
  162. .PP
  163. For reading, first line should be at most 1024 bytes long including newline
  164. unless the flag \fB\s-1BIO_FLAGS_BASE64_NO_NL\s0\fR is set.
  165. Further input lines can be of any length (i.e., newlines may appear anywhere
  166. in the input) and a newline at the end of input is not needed.
  167. .PP
  168. \&\fBBIO_flush()\fR on a base64 \s-1BIO\s0 that is being written through is
  169. used to signal that no more data is to be encoded: this is used
  170. to flush the final block through the \s-1BIO.\s0
  171. .PP
  172. The flag \fB\s-1BIO_FLAGS_BASE64_NO_NL\s0\fR can be set with \fBBIO_set_flags()\fR.
  173. For writing, it causes all data to be written on one line without
  174. newline at the end.
  175. For reading, it removes all expectations on newlines in the input data.
  176. .SH "NOTES"
  177. .IX Header "NOTES"
  178. Because of the format of base64 encoding the end of the encoded
  179. block cannot always be reliably determined.
  180. .SH "RETURN VALUES"
  181. .IX Header "RETURN VALUES"
  182. \&\fBBIO_f_base64()\fR returns the base64 \s-1BIO\s0 method.
  183. .SH "EXAMPLES"
  184. .IX Header "EXAMPLES"
  185. Base64 encode the string \*(L"Hello World\en\*(R" and write the result
  186. to standard output:
  187. .PP
  188. .Vb 2
  189. \& BIO *bio, *b64;
  190. \& char message[] = "Hello World \en";
  191. \&
  192. \& b64 = BIO_new(BIO_f_base64());
  193. \& bio = BIO_new_fp(stdout, BIO_NOCLOSE);
  194. \& BIO_push(b64, bio);
  195. \& BIO_write(b64, message, strlen(message));
  196. \& BIO_flush(b64);
  197. \&
  198. \& BIO_free_all(b64);
  199. .Ve
  200. .PP
  201. Read Base64 encoded data from standard input and write the decoded
  202. data to standard output:
  203. .PP
  204. .Vb 3
  205. \& BIO *bio, *b64, *bio_out;
  206. \& char inbuf[512];
  207. \& int inlen;
  208. \&
  209. \& b64 = BIO_new(BIO_f_base64());
  210. \& bio = BIO_new_fp(stdin, BIO_NOCLOSE);
  211. \& bio_out = BIO_new_fp(stdout, BIO_NOCLOSE);
  212. \& BIO_push(b64, bio);
  213. \& while ((inlen = BIO_read(b64, inbuf, 512)) > 0)
  214. \& BIO_write(bio_out, inbuf, inlen);
  215. \&
  216. \& BIO_flush(bio_out);
  217. \& BIO_free_all(b64);
  218. .Ve
  219. .SH "BUGS"
  220. .IX Header "BUGS"
  221. On decoding, if the flag \fB\s-1BIO_FLAGS_BASE64_NO_NL\s0\fR is not set and
  222. the first 1024 bytes of input do not include a newline character
  223. the first two lines of input are ignored.
  224. .PP
  225. The ambiguity of \s-1EOF\s0 in base64 encoded data can cause additional
  226. data following the base64 encoded block to be misinterpreted.
  227. .PP
  228. There should be some way of specifying a test that the \s-1BIO\s0 can perform
  229. to reliably determine \s-1EOF\s0 (for example a \s-1MIME\s0 boundary).
  230. .SH "COPYRIGHT"
  231. .IX Header "COPYRIGHT"
  232. Copyright 2000\-2024 The OpenSSL Project Authors. All Rights Reserved.
  233. .PP
  234. Licensed under the Apache License 2.0 (the \*(L"License\*(R"). You may not use
  235. this file except in compliance with the License. You can obtain a copy
  236. in the file \s-1LICENSE\s0 in the source distribution or at
  237. <https://www.openssl.org/source/license.html>.