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/* ========================================================================
* Copyright 2020-2022 Eduardo Chappa
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
*
* ========================================================================
*/
#include "oauth2_aux.h"
long auth_oauthbearer_client (authchallenge_t challenger,authrespond_t responder, char *base,
char *service,NETMBX *mb,void *stream, unsigned long port,
unsigned long *trial,char *user);
AUTHENTICATOR auth_bea = {
AU_HIDE | AU_SINGLE, /* hidden, single trip */
BEARERNAME, /* authenticator name */
NIL, /* always valid */
auth_oauthbearer_client, /* client method */
NIL, /* server method */
NIL /* next authenticator */
};
#define BEARER_ACCOUNT "n,a="
#define BEARER_ACCOUNT_LEN (4)
#ifndef OAUTH2_BEARER
#define OAUTH2_BEARER "auth=Bearer "
#endif
#ifndef OAUTH2_BEARER_LEN
#define OAUTH2_BEARER_LEN (12)
#endif
#define BEARER_HOST "host="
#define BEARER_HOST_LEN (5)
#define BEARER_PORT "port="
#define BEARER_PORT_LEN (5)
/* Client authenticator
* Accepts: challenger function
* responder function
* SASL service name
* parsed network mailbox structure
* stream argument for functions
* pointer to current trial count
* returned user name
* Returns: T if success, NIL otherwise, number of trials incremented if retry
*/
long auth_oauthbearer_client (authchallenge_t challenger,authrespond_t responder,char *base,
char *service,NETMBX *mb,void *stream, unsigned long port,
unsigned long *trial,char *user)
{
void *challenge;
unsigned long clen;
long ret = NIL;
OAUTH2_S oauth2;
int tryanother = 0; /* try another authentication method */
memset((void *) &oauth2, 0, sizeof(OAUTH2_S));
/* snarl if not SSL/TLS session */
if (!mb->sslflag && !mb->tlsflag)
mm_log ("SECURITY PROBLEM: insecure server advertised AUTH=OAUTHBEARER",WARN);
/* get initial (empty) challenge */
if (base || (challenge = (*challenger) (stream,&clen)) != NULL) {
if(base == NIL){
fs_give ((void **) &challenge);
if (clen) { /* abort if challenge non-empty */
mm_log ("Server bug: non-empty initial OAUTHBEARER challenge",WARN);
(*responder) (stream,NIL,NIL,0);
ret = LONGT; /* will get a BAD response back */
}
}
mm_login_method (mb, user, (void *) &oauth2, *trial, BEARERNAME);
if(oauth2.param[OA2_State].value)
fs_give((void **) &oauth2.param[OA2_State].value);
oauth2.param[OA2_State].value = oauth2_generate_state();
oauth2_code_challenge(&oauth2);
oauth2_login_hint(&oauth2, user);
/*
* If we did not get an access token, try to get one through
* our internal functions
*/
if(oauth2.name && oauth2.access_token == NIL){
char *RefreshToken = NIL;
if(oauth2.param[OA2_RefreshToken].value)
RefreshToken = cpystr(oauth2.param[OA2_RefreshToken].value);
mm_login_oauth2_c_client_method (mb, user, BEARERNAME, &oauth2, *trial, &tryanother);
/*
* if we got an access token from the c_client_method call,
* or somehow there was a change in the refresh token, return
* it to the client so that it will save it.
*/
if(!tryanother
&& (oauth2.access_token
|| (!RefreshToken && oauth2.param[OA2_RefreshToken].value)
|| (RefreshToken && oauth2.param[OA2_RefreshToken].value
&& strcmp(RefreshToken, oauth2.param[OA2_RefreshToken].value))
|| oauth2.cancel_refresh_token))
mm_login_method (mb, user, (void *) &oauth2, *trial, BEARERNAME);
if(RefreshToken)
fs_give((void **) &RefreshToken);
}
/* empty challenge or user requested abort or client does not have info */
if(tryanother || !oauth2.access_token) {
if (!base)
(*responder) (stream,NIL,NIL,0);
*trial = 0; /* cancel subsequent attempts */
ret = base ? NIL : LONGT; /* will get a BAD response back */
}
else {
char ports[10];
unsigned long rlen;
char *response;
sprintf(ports, "%lu", port);
rlen = BEARER_ACCOUNT_LEN + strlen(user) + 1 + 1
+ BEARER_HOST_LEN + strlen(mb->orighost) + 1
+ BEARER_PORT_LEN + strlen(ports) + 1
+ OAUTH2_BEARER_LEN + strlen(oauth2.access_token) + 2;
response = (char *) fs_get (rlen+1);
sprintf(response, "%s%s,\001%s%s\001%s%s\001%s%s\001\001", BEARER_ACCOUNT, user,
BEARER_HOST, mb->orighost, BEARER_PORT, ports, OAUTH2_BEARER, oauth2.access_token);
if ((*responder) (stream,base,response,rlen)) {
if ((challenge = (*challenger) (stream,&clen)) != NULL)
fs_give ((void **) &challenge);
else {
++*trial; /* can try again if necessary */
ret = *trial < 3 ? LONGT : NIL; /* check the authentication */
/* When the Access Token expires we fail once, but after we get
* a new one, we should succeed at the second attempt. If the
* Refresh Token has expired somehow, we invalidate it if we
* reach *trial to 3. This forces the process to restart later on.
*/
if(*trial == 3)
oauth2.expiration = 0L;
}
}
fs_give ((void **) &response);
if (!ret)
*trial = 65535; /* don't retry if bad protocol */
}
}
oauth2_free_extra_values(oauth2);
return ret;
}
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