2

Cyrus SASL api 不支持 EXTERNAL 机制吗？我正在尝试将其用作客户端，但SASL_NOMECH在询问时它会返回。

% 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
%

不过，我浏览了源代码，看起来所有客户端都应该支持 EXTERNAL 机制：

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

所以我猜我在这里做错了什么。我尝试将所有sasl_callback_t我能想到的 s 添加到sasl_client_*()，但没有一个被调用。是否有一些我应该通过的论点断言 EXTERNAL 是一种可接受的机制？或者 SASL_NOMECH 是否总是为 EXTERNAL 返回 - b/c 似乎不正确。

谁能帮我吗？

4

2 回答 2

1

好的，我找到了遗漏的步骤。

根据sasl/sasl.h，我需要SASL_AUTH_EXTERNAL为我的第一个设置属性sasl_conn_t：

/* 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.
 */

一旦我这样做了，剩下的就解决了：

% 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

但是，由于预装在 OS X 10.5 上的 Cyrus SASL 版本中存在一个错误，导致外部插件需要SASL_CB_USER回调并将其传递给 NULL 指针以存储其返回值，这仍然意味着我将拥有在所有这些机器上更新 Cyrus SASL。

或者也许我会围绕这个错误编写代码。

于 2009-03-25T20:59:34.743 回答
0

这是因为 Cyrus SASL 是在没有任何机制的情况下编译的（默认情况下假定它们是动态链接的）。因此，如果没有动态链接机制，它将报告没有匹配机制。

因此，更好的答案是使用静态链接的机制（在 Cyrus 包中称为插件）重新编译 Cyrus SASL。如果您查看 config.h 标头并将相应的静态定义 #define 为 1 然后重新编译（我手动将插件目录中的插件源添加到 libsasl2.a 存档）。然后，当您链接此库时，您将不会收到该错误（没有您找到的解决方法）。

于 2012-08-14T00:00:00.340 回答