Initial Commit

openssl-1.0.2f/doc/ssl/SSL_CTX_load_verify_locations.pod

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+=pod
+
+=head1 NAME
+
+SSL_CTX_load_verify_locations - set default locations for trusted CA
+certificates
+
+=head1 SYNOPSIS
+
+ #include <openssl/ssl.h>
+
+ int SSL_CTX_load_verify_locations(SSL_CTX *ctx, const char *CAfile,
+                                   const char *CApath);
+
+=head1 DESCRIPTION
+
+SSL_CTX_load_verify_locations() specifies the locations for B<ctx>, at
+which CA certificates for verification purposes are located. The certificates
+available via B<CAfile> and B<CApath> are trusted.
+
+=head1 NOTES
+
+If B<CAfile> is not NULL, it points to a file of CA certificates in PEM
+format. The file can contain several CA certificates identified by
+
+ -----BEGIN CERTIFICATE-----
+ ... (CA certificate in base64 encoding) ...
+ -----END CERTIFICATE-----
+
+sequences. Before, between, and after the certificates text is allowed
+which can be used e.g. for descriptions of the certificates.
+
+The B<CAfile> is processed on execution of the SSL_CTX_load_verify_locations()
+function.
+
+If B<CApath> is not NULL, it points to a directory containing CA certificates
+in PEM format. The files each contain one CA certificate. The files are
+looked up by the CA subject name hash value, which must hence be available.
+If more than one CA certificate with the same name hash value exist, the
+extension must be different (e.g. 9d66eef0.0, 9d66eef0.1 etc). The search
+is performed in the ordering of the extension number, regardless of other
+properties of the certificates.
+Use the B<c_rehash> utility to create the necessary links.
+
+The certificates in B<CApath> are only looked up when required, e.g. when
+building the certificate chain or when actually performing the verification
+of a peer certificate.
+
+When looking up CA certificates, the OpenSSL library will first search the
+certificates in B<CAfile>, then those in B<CApath>. Certificate matching
+is done based on the subject name, the key identifier (if present), and the
+serial number as taken from the certificate to be verified. If these data
+do not match, the next certificate will be tried. If a first certificate
+matching the parameters is found, the verification process will be performed;
+no other certificates for the same parameters will be searched in case of
+failure.
+
+In server mode, when requesting a client certificate, the server must send
+the list of CAs of which it will accept client certificates. This list
+is not influenced by the contents of B<CAfile> or B<CApath> and must
+explicitly be set using the
+L<SSL_CTX_set_client_CA_list(3)|SSL_CTX_set_client_CA_list(3)>
+family of functions.
+
+When building its own certificate chain, an OpenSSL client/server will
+try to fill in missing certificates from B<CAfile>/B<CApath>, if the
+certificate chain was not explicitly specified (see
+L<SSL_CTX_add_extra_chain_cert(3)|SSL_CTX_add_extra_chain_cert(3)>,
+L<SSL_CTX_use_certificate(3)|SSL_CTX_use_certificate(3)>.
+
+=head1 WARNINGS
+
+If several CA certificates matching the name, key identifier, and serial
+number condition are available, only the first one will be examined. This
+may lead to unexpected results if the same CA certificate is available
+with different expiration dates. If a "certificate expired" verification
+error occurs, no other certificate will be searched. Make sure to not
+have expired certificates mixed with valid ones.
+
+=head1 EXAMPLES
+
+Generate a CA certificate file with descriptive text from the CA certificates
+ca1.pem ca2.pem ca3.pem:
+
+ #!/bin/sh
+ rm CAfile.pem
+ for i in ca1.pem ca2.pem ca3.pem ; do
+   openssl x509 -in $i -text >> CAfile.pem
+ done
+
+Prepare the directory /some/where/certs containing several CA certificates
+for use as B<CApath>:
+
+ cd /some/where/certs
+ c_rehash .
+
+=head1 RETURN VALUES
+
+The following return values can occur:
+
+=over 4
+
+=item Z<>0
+
+The operation failed because B<CAfile> and B<CApath> are NULL or the
+processing at one of the locations specified failed. Check the error
+stack to find out the reason.
+
+=item Z<>1
+
+The operation succeeded.
+
+=back
+
+=head1 SEE ALSO
+
+L<ssl(3)|ssl(3)>,
+L<SSL_CTX_set_client_CA_list(3)|SSL_CTX_set_client_CA_list(3)>,
+L<SSL_get_client_CA_list(3)|SSL_get_client_CA_list(3)>,
+L<SSL_CTX_use_certificate(3)|SSL_CTX_use_certificate(3)>,
+L<SSL_CTX_add_extra_chain_cert(3)|SSL_CTX_add_extra_chain_cert(3)>,
+L<SSL_CTX_set_cert_store(3)|SSL_CTX_set_cert_store(3)>
+
+=cut