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[openssl.git] / doc / crypto / SMIME_read_PKCS7.pod

diff --git a/doc/crypto/SMIME_read_PKCS7.pod b/doc/crypto/SMIME_read_PKCS7.pod
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+=pod
+
+=head1 NAME
+
+SMIME_read_PKCS7 - parse S/MIME message.
+
+=head1 SYNOPSIS
+
+PKCS7 *SMIME_read_PKCS7(BIO *in, BIO **bcont);
+
+=head1 DESCRIPTION
+
+SMIME_read_PKCS7() parses a message in S/MIME format.
+
+B<in> is a BIO to read the message from.
+
+If cleartext signing is used then the content is saved in
+a memory bio which is written to B<*bcont>, otherwise
+B<*bcont> is set to B<NULL>.
+
+The parsed PKCS#7 structure is returned or B<NULL> if an
+error occurred.
+
+=head1 NOTES
+
+If B<*bcont> is not B<NULL> then the message is clear text
+signed. B<*bcont> can then be passed to PKCS7_verify() with
+the B<PKCS7_DETACHED> flag set.
+
+Otherwise the type of the returned structure can be determined
+using PKCS7_type().
+
+To support future functionality if B<bcont> is not B<NULL>
+B<*bcont> should be initialized to B<NULL>. For example:
+
+ BIO *cont = NULL;
+ PKCS7 *p7;
+
+ p7 = SMIME_read_PKCS7(in, &cont);
+
+=head1 BUGS
+
+The MIME parser used by SMIME_read_PKCS7() is somewhat primitive.
+While it will handle most S/MIME messages more complex compound
+formats may not work.
+
+The parser assumes that the PKCS7 structure is always base64
+encoded and will not handle the case where it is in binary format
+or uses quoted printable format.
+
+The use of a memory BIO to hold the signed content limits the size
+of message which can be processed due to memory restraints: a
+streaming single pass option should be available.
+
+=head1 RETURN VALUES
+
+SMIME_read_PKCS7() returns a valid B<PKCS7> structure or B<NULL>
+is an error occurred. The error can be obtained from ERR_get_error(3).
+
+=head1 SEE ALSO
+
+L<ERR_get_error(3)|ERR_get_error(3)>, L<PKCS7_type(3)|PKCS7_type(3)>
+L<SMIME_read_PKCS7(3)|SMIME_read_PKCS7(3)>, L<PKCS7_sign(3)|PKCS7_sign(3)>,
+L<PKCS7_verify(3)|PKCS7_verify(3)>, L<PKCS7_encrypt(3)|PKCS7_encrypt(3)>
+L<PKCS7_decrypt(3)|PKCS7_decrypt(3)>
+
+=head1 HISTORY
+
+SMIME_read_PKCS7() was added to OpenSSL 0.9.5
+
+=cut