OM_uint32 gss_accept_sec_context(OM_uint32 * minor_status, gss_ctx_id_t * context_handle, const gss_cred_id_t acceptor_cred_handle, const gss_buffer_t input_token_buffer, const gss_channel_bindings_t input_chan_bindings, gss_name_t * src_name, gss_OID * mech_type, gss_buffer_t output_token, OM_uint32 * ret_flags, OM_uint32 * time_rec, gss_cred_id_t * delegated_cred_handle);
Portable applications should be constructed to use the token length and return status to determine whether a token needs to be sent or waited for. Thus a typical portable caller should always invoke gss_accept_sec_context within a loop:
--------------------------------------------------- gss_ctx_id_t context_hdl = GSS_C_NO_CONTEXT;
do {
receive_token_from_peer(input_token);
maj_stat = gss_accept_sec_context(&min_stat,
&context_hdl,
cred_hdl,
input_token,
input_bindings,
&client_name,
&mech_type,
output_token,
&ret_flags,
&time_rec,
&deleg_cred);
if (GSS_ERROR(maj_stat)) {
report_error(maj_stat, min_stat);
};
if (output_token->length != 0) {
send_token_to_peer(output_token);
gss_release_buffer(&min_stat, output_token);
};
if (GSS_ERROR(maj_stat)) {
if (context_hdl != GSS_C_NO_CONTEXT)
gss_delete_sec_context(&min_stat,
&context_hdl,
GSS_C_NO_BUFFER);
break;
};
} while (maj_stat & GSS_S_CONTINUE_NEEDED);
---------------------------------------------------
Whenever the routine returns a major status that includes the value GSS_S_CONTINUE_NEEDED, the context is not fully established and the following restrictions apply to the output parameters:
The value returned via the time_rec parameter is undefined Unless the accompanying ret_flags parameter contains the bit GSS_C_PROT_READY_FLAG, indicating that per-message services may be applied in advance of a successful completion status, the value returned via the mech_type parameter may be undefined until the routine returns a major status value of GSS_S_COMPLETE.
The values of the GSS_C_DELEG_FLAG, GSS_C_MUTUAL_FLAG,GSS_C_REPLAY_FLAG, GSS_C_SEQUENCE_FLAG, GSS_C_CONF_FLAG,GSS_C_INTEG_FLAG and GSS_C_ANON_FLAG bits returned via the ret_flags parameter should contain the values that the implementation expects would be valid if context establishment were to succeed.
The values of the GSS_C_PROT_READY_FLAG and GSS_C_TRANS_FLAG bits within ret_flags should indicate the actual state at the time gss_accept_sec_context returns, whether or not the context is fully established.
Although this requires that GSS-API implementations set the GSS_C_PROT_READY_FLAG in the final ret_flags returned to a caller (i.e. when accompanied by a GSS_S_COMPLETE status code), applications should not rely on this behavior as the flag was not defined in Version 1 of the GSS-API. Instead, applications should be prepared to use per-message services after a successful context establishment, according to the GSS_C_INTEG_FLAG and GSS_C_CONF_FLAG values.
All other bits within the ret_flags argument should be set to zero. While the routine returns GSS_S_CONTINUE_NEEDED, the values returned via the ret_flags argument indicate the services that the implementation expects to be available from the established context.
If the initial call of gss_accept_sec_context() fails, the implementation should not create a context object, and should leave the value of the context_handle parameter set to GSS_C_NO_CONTEXT to indicate this. In the event of a failure on a subsequent call, the implementation is permitted to delete the "half-built" security context (in which case it should set the context_handle parameter to GSS_C_NO_CONTEXT), but the preferred behavior is to leave the security context (and the context_handle parameter) untouched for the application to delete (using gss_delete_sec_context).
During context establishment, the informational status bits GSS_S_OLD_TOKEN and GSS_S_DUPLICATE_TOKEN indicate fatal errors, and GSS-API mechanisms should always return them in association with a routine error of GSS_S_FAILURE. This requirement for pairing did not exist in version 1 of the GSS-API specification, so applications that wish to run over version 1 implementations must special-case these codes.
The `ret_flags` values:
`GSS_C_DELEG_FLAG`:: - True - Delegated credentials are available via the delegated_cred_handle parameter. - False - No credentials were delegated.
`GSS_C_MUTUAL_FLAG`:: - True - Remote peer asked for mutual authentication. - False - Remote peer did not ask for mutual authentication.
`GSS_C_REPLAY_FLAG`:: - True - replay of protected messages will be detected. - False - replayed messages will not be detected.
`GSS_C_SEQUENCE_FLAG`:: - True - out-of-sequence protected messages will be detected. - False - out-of-sequence messages will not be detected.
`GSS_C_CONF_FLAG`:: - True - Confidentiality service may be invoked by calling the gss_wrap routine. - False - No confidentiality service (via gss_wrap) available. gss_wrap will provide message encapsulation, data-origin authentication and integrity services only.
`GSS_C_INTEG_FLAG`:: - True - Integrity service may be invoked by calling either gss_get_mic or gss_wrap routines. - False - Per-message integrity service unavailable.
`GSS_C_ANON_FLAG`:: - True - The initiator does not wish to be authenticated; the src_name parameter (if requested) contains an anonymous internal name. - False - The initiator has been authenticated normally.
`GSS_C_PROT_READY_FLAG`:: - True - Protection services (as specified by the states of the GSS_C_CONF_FLAG and GSS_C_INTEG_FLAG) are available if the accompanying major status return value is either GSS_S_COMPLETE or GSS_S_CONTINUE_NEEDED. - False - Protection services (as specified by the states of the GSS_C_CONF_FLAG and GSS_C_INTEG_FLAG) are available only if the accompanying major status return value is GSS_S_COMPLETE.
`GSS_C_TRANS_FLAG`:: - True - The resultant security context may be transferred to other processes via a call to gss_export_sec_context(). - False - The security context is not transferable.
All other bits should be set to zero.
`GSS_S_CONTINUE_NEEDED`: Indicates that a token from the peer application is required to complete the context, and that gss_accept_sec_context must be called again with that token.
`GSS_S_DEFECTIVE_TOKEN`: Indicates that consistency checks performed on the input_token failed.
`GSS_S_DEFECTIVE_CREDENTIAL`: Indicates that consistency checks performed on the credential failed.
`GSS_S_NO_CRED`: The supplied credentials were not valid for context acceptance, or the credential handle did not reference any credentials.
`GSS_S_CREDENTIALS_EXPIRED`: The referenced credentials have expired.
`GSS_S_BAD_BINDINGS`: The input_token contains different channel bindings to those specified via the input_chan_bindings parameter.
`GSS_S_NO_CONTEXT`: Indicates that the supplied context handle did not refer to a valid context.
`GSS_S_BAD_SIG`: The input_token contains an invalid MIC.
`GSS_S_OLD_TOKEN`: The input_token was too old. This is a fatal error during context establishment.
`GSS_S_DUPLICATE_TOKEN`: The input_token is valid, but is a duplicate of a token already processed. This is a fatal error during context establishment.
`GSS_S_BAD_MECH`: The received token specified a mechanism that is not supported by the implementation or the provided credential.
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