1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
|
.\" Automatically generated by Pod::Man 2.28 (Pod::Simple 3.28)
.\"
.\" Standard preamble:
.\" ========================================================================
.de Sp \" Vertical space (when we can't use .PP)
.if t .sp .5v
.if n .sp
..
.de Vb \" Begin verbatim text
.ft CW
.nf
.ne \\$1
..
.de Ve \" End verbatim text
.ft R
.fi
..
.\" Set up some character translations and predefined strings. \*(-- will
.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
.\" double quote, and \*(R" will give a right double quote. \*(C+ will
.\" give a nicer C++. Capital omega is used to do unbreakable dashes and
.\" therefore won't be available. \*(C` and \*(C' expand to `' in nroff,
.\" nothing in troff, for use with C<>.
.tr \(*W-
.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
.ie n \{\
. ds -- \(*W-
. ds PI pi
. if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
. if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch
. ds L" ""
. ds R" ""
. ds C` ""
. ds C' ""
'br\}
.el\{\
. ds -- \|\(em\|
. ds PI \(*p
. ds L" ``
. ds R" ''
. ds C`
. ds C'
'br\}
.\"
.\" Escape single quotes in literal strings from groff's Unicode transform.
.ie \n(.g .ds Aq \(aq
.el .ds Aq '
.\"
.\" If the F register is turned on, we'll generate index entries on stderr for
.\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
.\" entries marked with X<> in POD. Of course, you'll have to process the
.\" output yourself in some meaningful fashion.
.\"
.\" Avoid warning from groff about undefined register 'F'.
.de IX
..
.nr rF 0
.if \n(.g .if rF .nr rF 1
.if (\n(rF:(\n(.g==0)) \{
. if \nF \{
. de IX
. tm Index:\\$1\t\\n%\t"\\$2"
..
. if !\nF==2 \{
. nr % 0
. nr F 2
. \}
. \}
.\}
.rr rF
.\"
.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
.\" Fear. Run. Save yourself. No user-serviceable parts.
. \" fudge factors for nroff and troff
.if n \{\
. ds #H 0
. ds #V .8m
. ds #F .3m
. ds #[ \f1
. ds #] \fP
.\}
.if t \{\
. ds #H ((1u-(\\\\n(.fu%2u))*.13m)
. ds #V .6m
. ds #F 0
. ds #[ \&
. ds #] \&
.\}
. \" simple accents for nroff and troff
.if n \{\
. ds ' \&
. ds ` \&
. ds ^ \&
. ds , \&
. ds ~ ~
. ds /
.\}
.if t \{\
. ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u"
. ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u'
. ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u'
. ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u'
. ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u'
. ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u'
.\}
. \" troff and (daisy-wheel) nroff accents
.ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V'
.ds 8 \h'\*(#H'\(*b\h'-\*(#H'
.ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#]
.ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H'
.ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u'
.ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#]
.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
.ds ae a\h'-(\w'a'u*4/10)'e
.ds Ae A\h'-(\w'A'u*4/10)'E
. \" corrections for vroff
.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u'
. \" for low resolution devices (crt and lpr)
.if \n(.H>23 .if \n(.V>19 \
\{\
. ds : e
. ds 8 ss
. ds o a
. ds d- d\h'-1'\(ga
. ds D- D\h'-1'\(hy
. ds th \o'bp'
. ds Th \o'LP'
. ds ae ae
. ds Ae AE
.\}
.rm #[ #] #H #V #F C
.\" ========================================================================
.\"
.IX Title "X509_check_host 3"
.TH X509_check_host 3 "2016-09-26" "1.0.2j" "OpenSSL"
.\" For nroff, turn off justification. Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
X509_check_host, X509_check_email, X509_check_ip, X509_check_ip_asc \- X.509 certificate matching
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/x509.h>
\&
\& int X509_check_host(X509 *, const char *name, size_t namelen,
\& unsigned int flags, char **peername);
\& int X509_check_email(X509 *, const char *address, size_t addresslen,
\& unsigned int flags);
\& int X509_check_ip(X509 *, const unsigned char *address, size_t addresslen,
\& unsigned int flags);
\& int X509_check_ip_asc(X509 *, const char *address, unsigned int flags);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
The certificate matching functions are used to check whether a
certificate matches a given host name, email address, or \s-1IP\s0 address.
The validity of the certificate and its trust level has to be checked by
other means.
.PP
\&\fIX509_check_host()\fR checks if the certificate Subject Alternative
Name (\s-1SAN\s0) or Subject CommonName (\s-1CN\s0) matches the specified host
name, which must be encoded in the preferred name syntax described
in section 3.5 of \s-1RFC 1034. \s0 By default, wildcards are supported
and they match only in the left-most label; but they may match
part of that label with an explicit prefix or suffix. For example,
by default, the host \fBname\fR \*(L"www.example.com\*(R" would match a
certificate with a \s-1SAN\s0 or \s-1CN\s0 value of \*(L"*.example.com\*(R", \*(L"w*.example.com\*(R"
or \*(L"*w.example.com\*(R".
.PP
Per section 6.4.2 of \s-1RFC 6125, \s0\fBname\fR values representing international
domain names must be given in A\-label form. The \fBnamelen\fR argument
must be the number of characters in the name string or zero in which
case the length is calculated with strlen(\fBname\fR). When \fBname\fR starts
with a dot (e.g \*(L".example.com\*(R"), it will be matched by a certificate
valid for any sub-domain of \fBname\fR, (see also
\&\fBX509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS\fR below).
.PP
When the certificate is matched, and \fBpeername\fR is not \s-1NULL,\s0 a
pointer to a copy of the matching \s-1SAN\s0 or \s-1CN\s0 from the peer certificate
is stored at the address passed in \fBpeername\fR. The application
is responsible for freeing the peername via \fIOPENSSL_free()\fR when it
is no longer needed.
.PP
\&\fIX509_check_email()\fR checks if the certificate matches the specified
email \fBaddress\fR. Only the mailbox syntax of \s-1RFC 822\s0 is supported,
comments are not allowed, and no attempt is made to normalize quoted
characters. The \fBaddresslen\fR argument must be the number of
characters in the address string or zero in which case the length
is calculated with strlen(\fBaddress\fR).
.PP
\&\fIX509_check_ip()\fR checks if the certificate matches a specified IPv4 or
IPv6 address. The \fBaddress\fR array is in binary format, in network
byte order. The length is either 4 (IPv4) or 16 (IPv6). Only
explicitly marked addresses in the certificates are considered; \s-1IP\s0
addresses stored in \s-1DNS\s0 names and Common Names are ignored.
.PP
\&\fIX509_check_ip_asc()\fR is similar, except that the NUL-terminated
string \fBaddress\fR is first converted to the internal representation.
.PP
The \fBflags\fR argument is usually 0. It can be the bitwise \s-1OR\s0 of the
flags:
.IP "\fBX509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT\fR," 4
.IX Item "X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT,"
.PD 0
.IP "\fBX509_CHECK_FLAG_NO_WILDCARDS\fR," 4
.IX Item "X509_CHECK_FLAG_NO_WILDCARDS,"
.IP "\fBX509_CHECK_FLAG_NO_PARTIAL_WILDCARDS\fR," 4
.IX Item "X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS,"
.IP "\fBX509_CHECK_FLAG_MULTI_LABEL_WILDCARDS\fR." 4
.IX Item "X509_CHECK_FLAG_MULTI_LABEL_WILDCARDS."
.IP "\fBX509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS\fR." 4
.IX Item "X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS."
.PD
.PP
The \fBX509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT\fR flag causes the function
to consider the subject \s-1DN\s0 even if the certificate contains at least
one subject alternative name of the right type (\s-1DNS\s0 name or email
address as appropriate); the default is to ignore the subject \s-1DN\s0
when at least one corresponding subject alternative names is present.
.PP
If set, \fBX509_CHECK_FLAG_NO_WILDCARDS\fR disables wildcard
expansion; this only applies to \fBX509_check_host\fR.
.PP
If set, \fBX509_CHECK_FLAG_NO_PARTIAL_WILDCARDS\fR suppresses support
for \*(L"*\*(R" as wildcard pattern in labels that have a prefix or suffix,
such as: \*(L"www*\*(R" or \*(L"*www\*(R"; this only aplies to \fBX509_check_host\fR.
.PP
If set, \fBX509_CHECK_FLAG_MULTI_LABEL_WILDCARDS\fR allows a \*(L"*\*(R" that
constitutes the complete label of a \s-1DNS\s0 name (e.g. \*(L"*.example.com\*(R")
to match more than one label in \fBname\fR; this flag only applies
to \fBX509_check_host\fR.
.PP
If set, \fBX509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS\fR restricts \fBname\fR
values which start with \*(L".\*(R", that would otherwise match any sub-domain
in the peer certificate, to only match direct child sub-domains.
Thus, for instance, with this flag set a \fBname\fR of \*(L".example.com\*(R"
would match a peer certificate with a \s-1DNS\s0 name of \*(L"www.example.com\*(R",
but would not match a peer certificate with a \s-1DNS\s0 name of
\&\*(L"www.sub.example.com\*(R"; this flag only applies to \fBX509_check_host\fR.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
The functions return 1 for a successful match, 0 for a failed match
and \-1 for an internal error: typically a memory allocation failure
or an \s-1ASN.1\s0 decoding error.
.PP
All functions can also return \-2 if the input is malformed. For example,
\&\fIX509_check_host()\fR returns \-2 if the provided \fBname\fR contains embedded
NULs.
.SH "NOTES"
.IX Header "NOTES"
Applications are encouraged to use \fIX509_VERIFY_PARAM_set1_host()\fR
rather than explicitly calling \fIX509_check_host\fR\|(3). Host name
checks are out of scope with the \s-1\fIDANE\-EE\s0\fR\|(3) certificate usage,
and the internal checks will be suppressed as appropriate when
\&\s-1DANE\s0 support is added to OpenSSL.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fISSL_get_verify_result\fR\|(3),
\&\fIX509_VERIFY_PARAM_set1_host\fR\|(3),
\&\fIX509_VERIFY_PARAM_add1_host\fR\|(3),
\&\fIX509_VERIFY_PARAM_set1_email\fR\|(3),
\&\fIX509_VERIFY_PARAM_set1_ip\fR\|(3),
\&\fIX509_VERIFY_PARAM_set1_ipasc\fR\|(3)
.SH "HISTORY"
.IX Header "HISTORY"
These functions were added in OpenSSL 1.0.2.
|