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/* ========================================================================
* Copyright 2018 - 2020 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
*
*
* ========================================================================
*/
long auth_oauth2_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_oa2 = {
AU_HIDE | AU_SINGLE, /* hidden */
OA2NAME, /* authenticator name */
NIL, /* always valid */
auth_oauth2_client, /* client method */
NIL, /* server method */
NIL /* next authenticator */
};
#define OAUTH2_USER "user="
#define OAUTH2_USER_LEN (5) /* strlen(OAUTH2_USER) */
#define OAUTH2_BEARER "auth=Bearer "
#define OAUTH2_BEARER_LEN (12) /* strlen(OAUTH2_BEARER) */
/* 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_oauth2_client (authchallenge_t challenger,authrespond_t responder, char *base,
char *service,NETMBX *mb,void *stream, unsigned long port,
unsigned long *trial,char *user)
{
char *u;
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=XOAUTH2",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 XOAUTH2 challenge",WARN);
(*responder) (stream,NIL,NIL,0);
ret = LONGT; /* will get a BAD response back */
}
}
/*
* the call to mm_login_method is supposed to return the username
* and access token. If this is not known by the application, then
* we call our internal functions to get a refresh token, access token
* and expiration time.
*
* Programmers note: We always call mm_login_method at least once.
* The first call is done with empty parameters and it indicates
* we are asking the application to load it the best it can. Then
* the application returns the loaded value. If we get it fully loaded
* we use the value, but if we don't get it fully loaded, we call
* our internal functions to try to fully load it.
*
* If in the internal call we get it loaded, then we use these values
* to log in. At this time we call the app to send back the loaded values
* so it can save them for the next time we call. This is done in a
* second call to mm_login_method. If we do not get oauth2 back with
* fully loaded values we cancel authentication completely. If the
* user cannot load this variable, then the user, through the client,
* should disable XOAUTH2 as an authentication method and try a new one.
*
* If we make our internal mm_login_oauth2_c_client_method call,
* we might still need to call the client to get the access token,
* this is done through a callback declared by the client. If we need
* that information, but the callback is not declared, this process
* will fail, so we will check if that call is declared as soon as we
* know we should start it, and we will only start it if this callback
* is declared.
*
* We start this process by calling the client and loading oauth2
* with the required information as best as we can.
*/
mm_login_method (mb, user, (void *) &oauth2, *trial, OA2NAME);
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, OA2NAME, &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, OA2NAME);
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,base,NIL,0);
*trial = 0; /* cancel subsequent attempts */
ret = base ? NIL : LONGT; /* will get a BAD response back */
}
else {
unsigned long rlen = OAUTH2_USER_LEN + OAUTH2_BEARER_LEN + 2
+ strlen(user) + strlen(oauth2.access_token) + 1;
char *response = (char *) fs_get (rlen + 1);
sprintf(response, "%s%s\001%s%s\001\001", OAUTH2_USER, user, 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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