fc5ecaddd0
While stereotyped repetitions are frowned upon in literature, they serve a useful purpose in manual pages, because it is easier for the user to find certain information if it is always presented in the same way. For that reason, this commit harmonizes the varying formulations in the HISTORY section about which functions, flags, etc. were added in which OpenSSL version. It also attempts to make the pod files more grep friendly by avoiding to insert line breaks between the symbol names and the corresponding version number in which they were introduced (wherever possible). Some punctuation and typographical errors were fixed on the way. Reviewed-by: Tim Hudson <tjh@openssl.org> (Merged from https://github.com/openssl/openssl/pull/7854)
118 lines
4.4 KiB
Text
118 lines
4.4 KiB
Text
=pod
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=head1 NAME
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SSL_set1_host, SSL_add1_host, SSL_set_hostflags, SSL_get0_peername -
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SSL server verification parameters
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=head1 SYNOPSIS
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#include <openssl/ssl.h>
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int SSL_set1_host(SSL *s, const char *hostname);
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int SSL_add1_host(SSL *s, const char *hostname);
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void SSL_set_hostflags(SSL *s, unsigned int flags);
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const char *SSL_get0_peername(SSL *s);
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=head1 DESCRIPTION
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These functions configure server hostname checks in the SSL client.
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SSL_set1_host() sets the expected DNS hostname to B<name> clearing
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any previously specified host name or names. If B<name> is NULL,
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or the empty string the list of hostnames is cleared, and name
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checks are not performed on the peer certificate. When a non-empty
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B<name> is specified, certificate verification automatically checks
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the peer hostname via L<X509_check_host(3)> with B<flags> as specified
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via SSL_set_hostflags(). Clients that enable DANE TLSA authentication
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via L<SSL_dane_enable(3)> should leave it to that function to set
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the primary reference identifier of the peer, and should not call
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SSL_set1_host().
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SSL_add1_host() adds B<name> as an additional reference identifier
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that can match the peer's certificate. Any previous names set via
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SSL_set1_host() or SSL_add1_host() are retained, no change is made
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if B<name> is NULL or empty. When multiple names are configured,
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the peer is considered verified when any name matches. This function
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is required for DANE TLSA in the presence of service name indirection
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via CNAME, MX or SRV records as specified in RFC7671, RFC7672 or
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RFC7673.
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SSL_set_hostflags() sets the B<flags> that will be passed to
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L<X509_check_host(3)> when name checks are applicable, by default
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the B<flags> value is 0. See L<X509_check_host(3)> for the list
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of available flags and their meaning.
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SSL_get0_peername() returns the DNS hostname or subject CommonName
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from the peer certificate that matched one of the reference
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identifiers. When wildcard matching is not disabled, the name
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matched in the peer certificate may be a wildcard name. When one
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of the reference identifiers configured via SSL_set1_host() or
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SSL_add1_host() starts with ".", which indicates a parent domain prefix
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rather than a fixed name, the matched peer name may be a sub-domain
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of the reference identifier. The returned string is allocated by
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the library and is no longer valid once the associated B<ssl> handle
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is cleared or freed, or a renegotiation takes place. Applications
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must not free the return value.
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SSL clients are advised to use these functions in preference to
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explicitly calling L<X509_check_host(3)>. Hostname checks may be out
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of scope with the RFC7671 DANE-EE(3) certificate usage, and the
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internal check will be suppressed as appropriate when DANE is
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enabled.
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=head1 RETURN VALUES
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SSL_set1_host() and SSL_add1_host() return 1 for success and 0 for
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failure.
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SSL_get0_peername() returns NULL if peername verification is not
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applicable (as with RFC7671 DANE-EE(3)), or no trusted peername was
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matched. Otherwise, it returns the matched peername. To determine
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whether verification succeeded call L<SSL_get_verify_result(3)>.
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=head1 EXAMPLE
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Suppose "smtp.example.com" is the MX host of the domain "example.com".
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The calls below will arrange to match either the MX hostname or the
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destination domain name in the SMTP server certificate. Wildcards
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are supported, but must match the entire label. The actual name
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matched in the certificate (which might be a wildcard) is retrieved,
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and must be copied by the application if it is to be retained beyond
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the lifetime of the SSL connection.
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SSL_set_hostflags(ssl, X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS);
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if (!SSL_set1_host(ssl, "smtp.example.com"))
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/* error */
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if (!SSL_add1_host(ssl, "example.com"))
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/* error */
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/* XXX: Perform SSL_connect() handshake and handle errors here */
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if (SSL_get_verify_result(ssl) == X509_V_OK) {
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const char *peername = SSL_get0_peername(ssl);
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if (peername != NULL)
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/* Name checks were in scope and matched the peername */
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}
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=head1 SEE ALSO
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L<X509_check_host(3)>,
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L<SSL_get_verify_result(3)>.
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L<SSL_dane_enable(3)>.
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=head1 HISTORY
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These functions were added in OpenSSL 1.1.0.
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=head1 COPYRIGHT
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Copyright 2016-2018 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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