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/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/* kdc/dispatch.c - Dispatch an incoming packet */
/*
* Copyright 1990, 2009 by the Massachusetts Institute of Technology.
*
* Export of this software from the United States of America may
* require a specific license from the United States Government.
* It is the responsibility of any person or organization contemplating
* export to obtain such a license before exporting.
*
* WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
* distribute this software and its documentation for any purpose and
* without fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright notice and
* this permission notice appear in supporting documentation, and that
* the name of M.I.T. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. Furthermore if you modify this software you must label
* your software as modified software and not distribute it in such a
* fashion that it might be confused with the original M.I.T. software.
* M.I.T. makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*/
#include "k5-int.h"
#include <syslog.h>
#include "kdc_util.h"
#include "extern.h"
#include "adm_proto.h"
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
static krb5_int32 last_usec = 0, last_os_random = 0;
static krb5_error_code make_too_big_error (krb5_data **out);
struct dispatch_state {
loop_respond_fn respond;
void *arg;
krb5_data *request;
int is_tcp;
};
static void
finish_dispatch(void *arg, krb5_error_code code, krb5_data *response)
{
struct dispatch_state *state = arg;
loop_respond_fn oldrespond;
void *oldarg;
assert(state);
oldrespond = state->respond;
oldarg = state->arg;
if (state->is_tcp == 0 && response &&
response->length > max_dgram_reply_size) {
krb5_free_data(kdc_context, response);
response = NULL;
code = make_too_big_error(&response);
if (code)
krb5_klog_syslog(LOG_ERR, "error constructing "
"KRB_ERR_RESPONSE_TOO_BIG error: %s",
error_message(code));
}
#ifndef NOCACHE
/* put the response into the lookaside buffer */
else if (!code)
kdc_insert_lookaside(state->request, response);
#endif
free(state);
(*oldrespond)(oldarg, code, response);
}
void
dispatch(void *cb, struct sockaddr *local_saddr, const krb5_fulladdr *from,
krb5_data *pkt, int is_tcp, loop_respond_fn respond, void *arg)
{
krb5_error_code retval;
krb5_kdc_req *as_req;
krb5_int32 now, now_usec;
krb5_data *response = NULL;
struct dispatch_state *state;
state = malloc(sizeof(*state));
if (!state) {
(*respond)(arg, ENOMEM, NULL);
return;
}
state->respond = respond;
state->arg = arg;
state->request = pkt;
state->is_tcp = is_tcp;
/* decode incoming packet, and dispatch */
#ifndef NOCACHE
/* try the replay lookaside buffer */
if (kdc_check_lookaside(pkt, &response)) {
/* a hit! */
const char *name = 0;
char buf[46];
if (is_tcp != 0 || response->length <= max_dgram_reply_size) {
name = inet_ntop (ADDRTYPE2FAMILY (from->address->addrtype),
from->address->contents, buf, sizeof (buf));
if (name == 0)
name = "[unknown address type]";
krb5_klog_syslog(LOG_INFO,
"DISPATCH: repeated (retransmitted?) request "
"from %s, resending previous response",
name);
}
finish_dispatch(state, 0, response);
return;
}
#endif
retval = krb5_crypto_us_timeofday(&now, &now_usec);
if (retval == 0) {
krb5_int32 usec_difference = now_usec-last_usec;
krb5_data data;
if(last_os_random == 0)
last_os_random = now;
/* Grab random data from OS every hour*/
if(now-last_os_random >= 60*60) {
krb5_c_random_os_entropy(kdc_context, 0, NULL);
last_os_random = now;
}
data.length = sizeof(krb5_int32);
data.data = (void *) &usec_difference;
krb5_c_random_add_entropy(kdc_context,
KRB5_C_RANDSOURCE_TIMING, &data);
last_usec = now_usec;
}
/* try TGS_REQ first; they are more common! */
if (krb5_is_tgs_req(pkt)) {
retval = process_tgs_req(pkt, from, &response);
} else if (krb5_is_as_req(pkt)) {
if (!(retval = decode_krb5_as_req(pkt, &as_req))) {
/*
* setup_server_realm() sets up the global realm-specific data
* pointer.
* process_as_req frees the request if it is called
*/
if (!(retval = setup_server_realm(as_req->server))) {
process_as_req(as_req, pkt, from, finish_dispatch, state);
return;
}
else
krb5_free_kdc_req(kdc_context, as_req);
}
} else
retval = KRB5KRB_AP_ERR_MSG_TYPE;
finish_dispatch(state, retval, response);
}
static krb5_error_code
make_too_big_error (krb5_data **out)
{
krb5_error errpkt;
krb5_error_code retval;
krb5_data *scratch;
*out = NULL;
memset(&errpkt, 0, sizeof(errpkt));
retval = krb5_us_timeofday(kdc_context, &errpkt.stime, &errpkt.susec);
if (retval)
return retval;
errpkt.error = KRB_ERR_RESPONSE_TOO_BIG;
errpkt.server = tgs_server;
errpkt.client = NULL;
errpkt.text.length = 0;
errpkt.text.data = 0;
errpkt.e_data.length = 0;
errpkt.e_data.data = 0;
scratch = malloc(sizeof(*scratch));
if (scratch == NULL)
return ENOMEM;
retval = krb5_mk_error(kdc_context, &errpkt, scratch);
if (retval) {
free(scratch);
return retval;
}
*out = scratch;
return 0;
}
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