Update build for OpenSSL-0.9.8j upgrade.
[dragonfly.git] / secure / lib / libcrypto / man / BIO_s_bio.3
CommitLineData
e257b235 1.\" Automatically generated by Pod::Man 2.16 (Pod::Simple 3.05)
8b0cefbb
JR
2.\"
3.\" Standard preamble:
4.\" ========================================================================
5.de Sh \" Subsection heading
984263bc
MD
6.br
7.if t .Sp
8.ne 5
9.PP
10\fB\\$1\fR
11.PP
12..
8b0cefbb 13.de Sp \" Vertical space (when we can't use .PP)
984263bc
MD
14.if t .sp .5v
15.if n .sp
16..
8b0cefbb 17.de Vb \" Begin verbatim text
984263bc
MD
18.ft CW
19.nf
20.ne \\$1
21..
8b0cefbb 22.de Ve \" End verbatim text
984263bc 23.ft R
984263bc
MD
24.fi
25..
8b0cefbb
JR
26.\" Set up some character translations and predefined strings. \*(-- will
27.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
e257b235
PA
28.\" double quote, and \*(R" will give a right double quote. \*(C+ will
29.\" give a nicer C++. Capital omega is used to do unbreakable dashes and
30.\" therefore won't be available. \*(C` and \*(C' expand to `' in nroff,
31.\" nothing in troff, for use with C<>.
32.tr \(*W-
8b0cefbb 33.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
984263bc 34.ie n \{\
8b0cefbb
JR
35. ds -- \(*W-
36. ds PI pi
37. if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
38. if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch
39. ds L" ""
40. ds R" ""
41. ds C` ""
42. ds C' ""
984263bc
MD
43'br\}
44.el\{\
8b0cefbb
JR
45. ds -- \|\(em\|
46. ds PI \(*p
47. ds L" ``
48. ds R" ''
984263bc 49'br\}
8b0cefbb 50.\"
e257b235
PA
51.\" Escape single quotes in literal strings from groff's Unicode transform.
52.ie \n(.g .ds Aq \(aq
53.el .ds Aq '
54.\"
8b0cefbb
JR
55.\" If the F register is turned on, we'll generate index entries on stderr for
56.\" titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and index
57.\" entries marked with X<> in POD. Of course, you'll have to process the
58.\" output yourself in some meaningful fashion.
e257b235 59.ie \nF \{\
8b0cefbb
JR
60. de IX
61. tm Index:\\$1\t\\n%\t"\\$2"
984263bc 62..
8b0cefbb
JR
63. nr % 0
64. rr F
984263bc 65.\}
e257b235
PA
66.el \{\
67. de IX
68..
69.\}
aac4ff6f 70.\"
8b0cefbb
JR
71.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
72.\" Fear. Run. Save yourself. No user-serviceable parts.
73. \" fudge factors for nroff and troff
984263bc 74.if n \{\
8b0cefbb
JR
75. ds #H 0
76. ds #V .8m
77. ds #F .3m
78. ds #[ \f1
79. ds #] \fP
984263bc
MD
80.\}
81.if t \{\
8b0cefbb
JR
82. ds #H ((1u-(\\\\n(.fu%2u))*.13m)
83. ds #V .6m
84. ds #F 0
85. ds #[ \&
86. ds #] \&
984263bc 87.\}
8b0cefbb 88. \" simple accents for nroff and troff
984263bc 89.if n \{\
8b0cefbb
JR
90. ds ' \&
91. ds ` \&
92. ds ^ \&
93. ds , \&
94. ds ~ ~
95. ds /
984263bc
MD
96.\}
97.if t \{\
8b0cefbb
JR
98. ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u"
99. ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u'
100. ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u'
101. ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u'
102. ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u'
103. ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u'
984263bc 104.\}
8b0cefbb 105. \" troff and (daisy-wheel) nroff accents
984263bc
MD
106.ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V'
107.ds 8 \h'\*(#H'\(*b\h'-\*(#H'
108.ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#]
109.ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H'
110.ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u'
111.ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#]
112.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
113.ds ae a\h'-(\w'a'u*4/10)'e
114.ds Ae A\h'-(\w'A'u*4/10)'E
8b0cefbb 115. \" corrections for vroff
984263bc
MD
116.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
117.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u'
8b0cefbb 118. \" for low resolution devices (crt and lpr)
984263bc
MD
119.if \n(.H>23 .if \n(.V>19 \
120\{\
8b0cefbb
JR
121. ds : e
122. ds 8 ss
123. ds o a
124. ds d- d\h'-1'\(ga
125. ds D- D\h'-1'\(hy
126. ds th \o'bp'
127. ds Th \o'LP'
128. ds ae ae
129. ds Ae AE
984263bc
MD
130.\}
131.rm #[ #] #H #V #F C
8b0cefbb
JR
132.\" ========================================================================
133.\"
134.IX Title "BIO_s_bio 3"
e257b235
PA
135.TH BIO_s_bio 3 "2009-01-11" "0.9.8j" "OpenSSL"
136.\" For nroff, turn off justification. Always turn off hyphenation; it makes
137.\" way too many mistakes in technical documents.
138.if n .ad l
139.nh
984263bc
MD
140.SH "NAME"
141BIO_s_bio, BIO_make_bio_pair, BIO_destroy_bio_pair, BIO_shutdown_wr,
142BIO_set_write_buf_size, BIO_get_write_buf_size, BIO_new_bio_pair,
143BIO_get_write_guarantee, BIO_ctrl_get_write_guarantee, BIO_get_read_request,
74dab6c2 144BIO_ctrl_get_read_request, BIO_ctrl_reset_read_request \- BIO pair BIO
984263bc 145.SH "SYNOPSIS"
8b0cefbb 146.IX Header "SYNOPSIS"
984263bc
MD
147.Vb 1
148\& #include <openssl/bio.h>
e257b235 149\&
984263bc 150\& BIO_METHOD *BIO_s_bio(void);
e257b235 151\&
984263bc
MD
152\& #define BIO_make_bio_pair(b1,b2) (int)BIO_ctrl(b1,BIO_C_MAKE_BIO_PAIR,0,b2)
153\& #define BIO_destroy_bio_pair(b) (int)BIO_ctrl(b,BIO_C_DESTROY_BIO_PAIR,0,NULL)
e257b235 154\&
984263bc 155\& #define BIO_shutdown_wr(b) (int)BIO_ctrl(b, BIO_C_SHUTDOWN_WR, 0, NULL)
e257b235 156\&
984263bc
MD
157\& #define BIO_set_write_buf_size(b,size) (int)BIO_ctrl(b,BIO_C_SET_WRITE_BUF_SIZE,size,NULL)
158\& #define BIO_get_write_buf_size(b,size) (size_t)BIO_ctrl(b,BIO_C_GET_WRITE_BUF_SIZE,size,NULL)
e257b235 159\&
984263bc 160\& int BIO_new_bio_pair(BIO **bio1, size_t writebuf1, BIO **bio2, size_t writebuf2);
e257b235 161\&
984263bc
MD
162\& #define BIO_get_write_guarantee(b) (int)BIO_ctrl(b,BIO_C_GET_WRITE_GUARANTEE,0,NULL)
163\& size_t BIO_ctrl_get_write_guarantee(BIO *b);
e257b235 164\&
984263bc
MD
165\& #define BIO_get_read_request(b) (int)BIO_ctrl(b,BIO_C_GET_READ_REQUEST,0,NULL)
166\& size_t BIO_ctrl_get_read_request(BIO *b);
e257b235 167\&
984263bc
MD
168\& int BIO_ctrl_reset_read_request(BIO *b);
169.Ve
170.SH "DESCRIPTION"
8b0cefbb
JR
171.IX Header "DESCRIPTION"
172\&\fIBIO_s_bio()\fR returns the method for a \s-1BIO\s0 pair. A \s-1BIO\s0 pair is a pair of source/sink
984263bc
MD
173BIOs where data written to either half of the pair is buffered and can be read from
174the other half. Both halves must usually by handled by the same application thread
175since no locking is done on the internal data structures.
176.PP
8b0cefbb
JR
177Since \s-1BIO\s0 chains typically end in a source/sink \s-1BIO\s0 it is possible to make this
178one half of a \s-1BIO\s0 pair and have all the data processed by the chain under application
984263bc
MD
179control.
180.PP
8b0cefbb 181One typical use of \s-1BIO\s0 pairs is to place \s-1TLS/SSL\s0 I/O under application control, this
984263bc 182can be used when the application wishes to use a non standard transport for
8b0cefbb 183\&\s-1TLS/SSL\s0 or the normal socket routines are inappropriate.
984263bc
MD
184.PP
185Calls to \fIBIO_read()\fR will read data from the buffer or request a retry if no
186data is available.
187.PP
188Calls to \fIBIO_write()\fR will place data in the buffer or request a retry if the
189buffer is full.
190.PP
191The standard calls \fIBIO_ctrl_pending()\fR and \fIBIO_ctrl_wpending()\fR can be used to
192determine the amount of pending data in the read or write buffer.
193.PP
8b0cefbb 194\&\fIBIO_reset()\fR clears any data in the write buffer.
984263bc 195.PP
8b0cefbb 196\&\fIBIO_make_bio_pair()\fR joins two separate BIOs into a connected pair.
984263bc 197.PP
8b0cefbb 198\&\fIBIO_destroy_pair()\fR destroys the association between two connected BIOs. Freeing
984263bc
MD
199up any half of the pair will automatically destroy the association.
200.PP
8b0cefbb
JR
201\&\fIBIO_shutdown_wr()\fR is used to close down a \s-1BIO\s0 \fBb\fR. After this call no further
202writes on \s-1BIO\s0 \fBb\fR are allowed (they will return an error). Reads on the other
203half of the pair will return any pending data or \s-1EOF\s0 when all pending data has
e257b235 204been read.
984263bc 205.PP
8b0cefbb 206\&\fIBIO_set_write_buf_size()\fR sets the write buffer size of \s-1BIO\s0 \fBb\fR to \fBsize\fR.
984263bc 207If the size is not initialized a default value is used. This is currently
8b0cefbb 20817K, sufficient for a maximum size \s-1TLS\s0 record.
984263bc 209.PP
8b0cefbb 210\&\fIBIO_get_write_buf_size()\fR returns the size of the write buffer.
984263bc 211.PP
8b0cefbb
JR
212\&\fIBIO_new_bio_pair()\fR combines the calls to \fIBIO_new()\fR, \fIBIO_make_bio_pair()\fR and
213\&\fIBIO_set_write_buf_size()\fR to create a connected pair of BIOs \fBbio1\fR, \fBbio2\fR
984263bc
MD
214with write buffer sizes \fBwritebuf1\fR and \fBwritebuf2\fR. If either size is
215zero then the default size is used. \fIBIO_new_bio_pair()\fR does not check whether
8b0cefbb
JR
216\&\fBbio1\fR or \fBbio2\fR do point to some other \s-1BIO\s0, the values are overwritten,
217\&\fIBIO_free()\fR is not called.
984263bc 218.PP
8b0cefbb
JR
219\&\fIBIO_get_write_guarantee()\fR and \fIBIO_ctrl_get_write_guarantee()\fR return the maximum
220length of data that can be currently written to the \s-1BIO\s0. Writes larger than this
984263bc
MD
221value will return a value from \fIBIO_write()\fR less than the amount requested or if the
222buffer is full request a retry. \fIBIO_ctrl_get_write_guarantee()\fR is a function
223whereas \fIBIO_get_write_guarantee()\fR is a macro.
224.PP
8b0cefbb 225\&\fIBIO_get_read_request()\fR and \fIBIO_ctrl_get_read_request()\fR return the
984263bc 226amount of data requested, or the buffer size if it is less, if the
8b0cefbb 227last read attempt at the other half of the \s-1BIO\s0 pair failed due to an
984263bc 228empty buffer. This can be used to determine how much data should be
8b0cefbb
JR
229written to the \s-1BIO\s0 so the next read will succeed: this is most useful
230in \s-1TLS/SSL\s0 applications where the amount of data read is usually
984263bc
MD
231meaningful rather than just a buffer size. After a successful read
232this call will return zero. It also will return zero once new data
233has been written satisfying the read request or part of it.
234Note that \fIBIO_get_read_request()\fR never returns an amount larger
235than that returned by \fIBIO_get_write_guarantee()\fR.
236.PP
8b0cefbb
JR
237\&\fIBIO_ctrl_reset_read_request()\fR can also be used to reset the value returned by
238\&\fIBIO_get_read_request()\fR to zero.
984263bc 239.SH "NOTES"
8b0cefbb
JR
240.IX Header "NOTES"
241Both halves of a \s-1BIO\s0 pair should be freed. That is even if one half is implicit
984263bc
MD
242freed due to a \fIBIO_free_all()\fR or \fISSL_free()\fR call the other half needs to be freed.
243.PP
8b0cefbb 244When used in bidirectional applications (such as \s-1TLS/SSL\s0) care should be taken to
984263bc
MD
245flush any data in the write buffer. This can be done by calling \fIBIO_pending()\fR
246on the other half of the pair and, if any data is pending, reading it and sending
247it to the underlying transport. This must be done before any normal processing
248(such as calling \fIselect()\fR ) due to a request and \fIBIO_should_read()\fR being true.
249.PP
250To see why this is important consider a case where a request is sent using
8b0cefbb
JR
251\&\fIBIO_write()\fR and a response read with \fIBIO_read()\fR, this can occur during an
252\&\s-1TLS/SSL\s0 handshake for example. \fIBIO_write()\fR will succeed and place data in the write
984263bc
MD
253buffer. \fIBIO_read()\fR will initially fail and \fIBIO_should_read()\fR will be true. If
254the application then waits for data to be available on the underlying transport
255before flushing the write buffer it will never succeed because the request was
256never sent!
257.SH "RETURN VALUES"
8b0cefbb
JR
258.IX Header "RETURN VALUES"
259\&\fIBIO_new_bio_pair()\fR returns 1 on success, with the new BIOs available in
260\&\fBbio1\fR and \fBbio2\fR, or 0 on failure, with \s-1NULL\s0 pointers stored into the
984263bc
MD
261locations for \fBbio1\fR and \fBbio2\fR. Check the error stack for more information.
262.PP
8b0cefbb 263[\s-1XXXXX:\s0 More return values need to be added here]
984263bc 264.SH "EXAMPLE"
8b0cefbb
JR
265.IX Header "EXAMPLE"
266The \s-1BIO\s0 pair can be used to have full control over the network access of an
984263bc 267application. The application can call \fIselect()\fR on the socket as required
e257b235 268without having to go through the SSL-interface.
984263bc
MD
269.PP
270.Vb 6
271\& BIO *internal_bio, *network_bio;
272\& ...
273\& BIO_new_bio_pair(internal_bio, 0, network_bio, 0);
274\& SSL_set_bio(ssl, internal_bio, internal_bio);
275\& SSL_operations();
276\& ...
e257b235
PA
277\&
278\& application | TLS\-engine
984263bc 279\& | |
e257b235 280\& +\-\-\-\-\-\-\-\-\-\-> SSL_operations()
984263bc
MD
281\& | /\e ||
282\& | || \e/
e257b235
PA
283\& | BIO\-pair (internal_bio)
284\& +\-\-\-\-\-\-\-\-\-\-< BIO\-pair (network_bio)
984263bc
MD
285\& | |
286\& socket |
e257b235 287\&
984263bc
MD
288\& ...
289\& SSL_free(ssl); /* implicitly frees internal_bio */
290\& BIO_free(network_bio);
291\& ...
292.Ve
8b0cefbb
JR
293.PP
294As the \s-1BIO\s0 pair will only buffer the data and never directly access the
984263bc
MD
295connection, it behaves non-blocking and will return as soon as the write
296buffer is full or the read buffer is drained. Then the application has to
297flush the write buffer and/or fill the read buffer.
298.PP
8b0cefbb 299Use the \fIBIO_ctrl_pending()\fR, to find out whether data is buffered in the \s-1BIO\s0
984263bc
MD
300and must be transfered to the network. Use \fIBIO_ctrl_get_read_request()\fR to
301find out, how many bytes must be written into the buffer before the
8b0cefbb 302\&\fISSL_operation()\fR can successfully be continued.
984263bc 303.SH "WARNING"
8b0cefbb
JR
304.IX Header "WARNING"
305As the data is buffered, \fISSL_operation()\fR may return with a \s-1ERROR_SSL_WANT_READ\s0
984263bc
MD
306condition, but there is still data in the write buffer. An application must
307not rely on the error value of \fISSL_operation()\fR but must assure that the
308write buffer is always flushed first. Otherwise a deadlock may occur as
309the peer might be waiting for the data before being able to continue.
310.SH "SEE ALSO"
74dab6c2 311.IX Header "SEE ALSO"
8b0cefbb
JR
312\&\fISSL_set_bio\fR\|(3), \fIssl\fR\|(3), \fIbio\fR\|(3),
313\&\fIBIO_should_retry\fR\|(3), \fIBIO_read\fR\|(3)