NE_SSL_SET_VERIFY(3) neon API reference NE_SSL_SET_VERIFY(3)
NAME
ne_ssl_set_verify - register an SSL certificate verification callback
SYNOPSIS
#include <ne_session.h>
typedef int ne_ssl_verify_fn(void *userdata, int failures, const ne_ssl_certificate *cert);
void ne_ssl_set_verify(ne_session *session, ne_ssl_verify_fn verify_fn, void *userdata);
DESCRIPTION
To enable manual SSL certificate verification, a callback can be registered using ne_ssl_set_verify. If such a callback is not registered,
when a connection is established to an SSL server which does not present a certificate signed by a trusted CA (see ne_ssl_trust_cert), or
if the certificate presented is invalid in some way, the connection will fail.
When the callback is invoked, the failures parameter gives a bitmask indicating in what way the automatic certificate verification failed.
The value is equal to the bit-wise OR of one or more of the following constants (and is guaranteed to be non-zero):
NE_SSL_NOTYETVALID
The certificate is not yet valid.
NE_SSL_EXPIRED
The certificate has expired.
NE_SSL_IDMISMATCH
The hostname used for the session does not match the hostname to which the certificate was issued.
NE_SSL_UNTRUSTED
The Certificate Authority which signed the certificate is not trusted.
Note that if either of the NE_SSL_IDMISMATCH or NE_SSL_UNTRUSTED failures is given, the connection may have been intercepted by a third
party, and must not be presumed to be "secure".
The cert parameter passed to the callback represents the certificate which was presented by the server. If the server presented a chain of
certificates, the chain can be accessed using ne_ssl_cert_signedby. The cert object given is not valid after the callback returns.
RETURN VALUE
The verification callback must return zero to indicate that the certificate should be trusted; and non-zero otherwise (in which case, the
connection will fail).
EXAMPLES
The following code implements an example verification callback, using the dump_cert function from ne_ssl_cert_subject to display
certification information. Notice that the hostname of the server used for the session is passed as the userdata parameter to the callback.
static int
my_verify(void *userdata, int failures, const ne_ssl_certificate *cert)
{
const char *hostname = userdata;
dump_cert(cert);
puts("Certificate verification failed - the connection may have been "
"intercepted by a third party!");
if (failures & NE_SSL_IDMISMATCH) {
const char *id = ne_ssl_cert_identity(cert);
if (id)
printf("Server certificate was issued to '%s' not '%s'.
",
id, hostname);
else
printf("The certificate was not issued for '%s'
", hostname);
}
if (failures & NE_SSL_UNTRUSTED)
puts("The certificate is not signed by a trusted Certificate Authority.");
/* ... check for validity failures ... */
if (prompt_user())
return 1; /* fail verification */
else
return 0; /* trust the certificate anyway */
}
int
main(...)
{
ne_session *sess = ne_session_create("https", "some.host.name", 443);
ne_ssl_set_verify(sess, my_verify, "some.host.name");
...
}
SEE ALSO
ne_ssl_trust_cert, ne_ssl_readable_dname, ne_ssl_cert_subject
AUTHOR
Joe Orton <neon@lists.manyfish.co.uk>
Author.
COPYRIGHT
neon 0.29.6 3 May 2011 NE_SSL_SET_VERIFY(3)