How to verify server side certificate ?

[huangjnb]

hi all, I am a newbie on openssl .I don't know how to verify server side cerificiate. In the cli.cpp that shiped with openssl I find the way to get server's certificate info as follow:

  /* Get server's certificate (note: beware of dynamic allocation) - opt */

  server_cert = SSL_get_peer_certificate (ssl);       CHK_NULL(server_cert);
  printf ("Server certificate:\n");
 
  str = X509_NAME_oneline (X509_get_subject_name (server_cert),0,0);
  CHK_NULL(str);
  printf ("\t subject: %s\n", str);
  Free (str);

  str = X509_NAME_oneline (X509_get_issuer_name  (server_cert),0,0);
  CHK_NULL(str);
  printf ("\t issuer: %s\n", str);
  Free (str);

  /* We could do all sorts of certificate verification stuff here before
     deallocating the certificate. */

  X509_free (server_cert);
How to do certificate verification stuff here?
Can you help me? Thanks!