NAME
SSL_CTX_set_max_cert_list, SSL_CTX_get_max_cert_list, SSL_set_max_cert_list, SSL_get_max_cert_list — manipulate allowed for the peer's certificate chain
Synopsis
#include <openssl/ssl.h>
long
SSL_CTX_set_max_cert_list(SSL_CTX *ctx, long size);
long
SSL_CTX_get_max_cert_list(SSL_CTX *ctx);
long SSL_set_max_cert_list(SSL
*ssl, long size);
long SSL_get_max_cert_list(SSL *ctx);
DESCRIPTION
SSL_CTX_set_max_cert_list() sets the maximum size allowed
for the peer's certificate chain for all SSL objects created from
ctx to be <size> bytes. The SSL objects inherit
the setting valid for ctx at the time SSL_new(3) is being called.
SSL_CTX_get_max_cert_list() returns the currently set maximum
size for ctx.
SSL_set_max_cert_list() sets the maximum size allowed for
the peer's certificate chain for ssl to be <size> bytes.
This setting stays valid until a new value is set.
SSL_get_max_cert_list() returns the currently set maximum
size for ssl.
NOTES
During the handshake process, the peer may send a certificate
chain. The TLS/SSL standard does not give any maximum size of the
certificate chain. The OpenSSL library handles incoming data by
a dynamically allocated buffer. In order to prevent this buffer
from growing without bounds due to data received from a faulty or
malicious peer, a maximum size for the certificate chain is set.
The default value for the maximum certificate chain size is
100kB (30kB on the 16bit DOS platform). This should be sufficient
for usual certificate chains (OpenSSL's default maximum chain length
is 10, see SSL_CTX_set_verify(3), and certificates without
special extensions have a typical size of 1-2kB).
For special applications it can be necessary to extend the
maximum certificate chain size allowed to be sent by the peer, see
e.g. the work on "Internet X.509 Public Key Infrastructure Proxy
Certificate Profile" and "TLS Delegation Protocol" at http://www.ietf.org/
and http://www.globus.org/ .
Under normal conditions it should never be necessary to set
a value smaller than the default, as the buffer is handled dynamically
and only uses the memory actually required by the data sent by the
peer.
If the maximum certificate chain size allowed is exceeded,
the handshake will fail with a SSL_R_EXCESSIVE_MESSAGE_SIZE error.
RETURN VALUES
SSL_CTX_set_max_cert_list() and SSL_set_max_cert_list() return
the previously set value.
SSL_CTX_get_max_cert_list() and SSL_get_max_cert_list() return
the currently set value.
SEE ALSO
ssl(3), SSL_new(3), SSL_CTX_set_verify(3)
HISTORY
SSL*_set/get_max_cert_list() have been introduced in OpenSSL
0.9.7.
