Does the Cyrus SASL api not support the EXTERNAL mechanism? I'm trying to
use it as a client, but it returns SASL_NOMECH when asked.
% cat cyrus_sal_ex.c
/* cyrus_sasl_ex.c: Example of using the Cyrus SASL api */
#include <stdio.h> /* for printf() */
#include <sasl/sasl.h> /* for sasl_client_*(), SASL_*, sasl_*_t */
static char const * SASL_return_code(int const code)
{
switch(code)
{
/* ... */
case SASL_OK: return "SASL_OK[0]: successful result";
/* ... */
case SASL_NOMECH: return "SASL_NOMECH[-4]: mechanism not supported";
/* ... */
}
return "unrecognized";
}
int main()
{
char const * output = NULL;
unsigned outlen = 0;
char const * mechanism = NULL;
sasl_conn_t * conn;
# define PRINT_RESULT( x ) do\
{\
int const __result = (x);\
printf("%s == %d\n\t%s\n", #x, __result, SASL_return_code(__result));\
if (__result < 0) goto done;\
}\
while (0)
PRINT_RESULT( sasl_client_init( NULL ) );
PRINT_RESULT( sasl_client_new( "fake", "fakey.mcfaker.ton", "127.0.0.1", "127.255.255.1", NULL, 0, &conn) );
PRINT_RESULT( sasl_client_start( conn, "EXTERNAL", NULL, &output, &outlen, &mechanism) );
done:
# undef PRINT_RESULT
printf("output: [%d bytes] : %s\n", outlen, (output ? output : "NULL") );
printf("mechanism: %s\n", (mechanism ? mechanism : "NULL"));
return 0;
}
% gcc -I/sw/include -L/sw/lib -lsasl2 cyrus_sasl_ex.c -o cyrus_sasl_ex # your header/library locations may vary
% ./cyrus_sasl_ex
sasl_client_init( NULL ) == 0
SASL_OK[0]: successful result
sasl_client_new( "fake", "fakey.mcfaker.ton", "127.0.0.1", "127.255.255.1", NULL, 0, &conn) == 0
SASL_OK[0]: successful result
sasl_client_start( conn, "EXTERNAL", NULL, &output, &outlen, &mechanism) == -4
SASL_NOMECH[-4]: mechanism not supported
output: [0 bytes] : NULL
mechanism: EXTERNAL
%
I browsed through the source though, and it looks like all the clients should support the EXTERNAL mechanism:
cyrus-sasl-2.1.22/lib/client.c:
196 int sasl_client_init(const sasl_callback_t *callbacks)
197 {
...
227
228 sasl_client_add_plugin("EXTERNAL", &external_client_plug_init);
229
So I'm guessing I'm doing something wrong here. I tried adding all the sasl_callback_ts I could think of to sasl_client_*(), but
none of them even got called. Is there some argument I should pass that asserts that EXTERNAL is an acceptable mechanism?
Or is SASL_NOMECH always returned for EXTERNAL - b/c that doesn't seem right.
Can anyone help me out?
Ok, I found the left out step.
According to sasl/sasl.h, I needed to set the SASL_AUTH_EXTERNAL property
for my sasl_conn_t first:
/* set property in SASL connection state
* returns:
* SASL_OK -- value set
* SASL_BADPARAM -- invalid property or value
*/
LIBSASL_API int sasl_setprop(sasl_conn_t *conn,
int propnum,
const void *value);
#define SASL_SSF_EXTERNAL 100 /* external SSF active (sasl_ssf_t *) */
#define SASL_SEC_PROPS 101 /* sasl_security_properties_t */
#define SASL_AUTH_EXTERNAL 102 /* external authentication ID (const char *) */
/* If the SASL_AUTH_EXTERNAL value is non-NULL, then a special version of the
* EXTERNAL mechanism is enabled (one for server-embedded EXTERNAL mechanisms).
* Otherwise, the EXTERNAL mechanism will be absent unless a plug-in
* including EXTERNAL is present.
*/
Once I did that, the rest worked out:
% cat cyrus_sasl_ex.c
/* Example of using the Cyrus SASL api */
#include <stdio.h> /* for printf() */
#include <sasl/sasl.h> /* for sasl_client_*(), SASL_*, sasl_*_t */
int main()
{
char const * output = NULL;
unsigned outlen = 0;
char const * mechanism = NULL;
sasl_conn_t * conn;
# define PRINT_RESULT( x ) do\
{\
int const __result = (x);\
printf("%s == %d\n\t%s\n", #x, __result, sasl_errstring(__result,NULL,NULL));\
if (__result < 0) goto done;\
}\
while (0)
PRINT_RESULT( sasl_client_init( NULL ) );
PRINT_RESULT( sasl_client_new( "fake", "fakey.mcfaker.ton", "127.0.0.1", "127.255.255.1", NULL, 0, &conn) );
PRINT_RESULT( sasl_setprop( conn, SASL_AUTH_EXTERNAL, "fake authority" ) );
PRINT_RESULT( sasl_client_start( conn, "EXTERNAL", NULL, &output, &outlen, &mechanism) );
done:
# undef PRINT_RESULT
printf("output: [%d bytes] : %s\n", outlen, (output ? output : "NULL") );
printf("mechanism: %s\n", (mechanism ? mechanism : "NULL"));
return 0;
}
% gcc -I/sw/include -L/sw/lib -lsasl2 cyrus_sasl_ex.c -o cyrus_sasl_ex
% ./cyrus_sasl_ex
sasl_client_init( NULL ) == 0
successful result
sasl_client_new( "fake", "fakey.mcfaker.ton", "127.0.0.1", "127.255.255.1", NULL, 0, &conn) == 0
successful result
sasl_setprop( conn, SASL_AUTH_EXTERNAL, "fake authority" ) == 0
successful result
sasl_client_start( conn, "EXTERNAL", NULL, &output, &outlen, &mechanism) == 0
successful result
output: [0 bytes] :
mechanism: EXTERNAL
However, since the version of Cyrus SASL that comes pre-installed on OS X 10.5 has a bug in it that makes the external plugin require a SASL_CB_USER callback and passes it a NULL pointer to store its return value in, this still means I'll have to update Cyrus SASL on all those machines.
Or maybe I'll just code around the bug.