summaryrefslogtreecommitdiff
path: root/imap/src/c-client/auth_oa2.c
blob: ea60f13f6fc22e8270c5ea07733895146a0390db (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
/* ========================================================================
 * 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);

#ifndef HTTP_OAUTH2_INCLUDED
void mm_login_oauth2_c_client_method (NETMBX *, char *, char *, OAUTH2_S *, unsigned long, int *);
#endif /* HTTP_OAUTH2_INCLUDED */

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_BEARER	"auth=Bearer "

#ifndef OAUTH2_GENERATE_STATE
#define OAUTH2_GENERATE_STATE
char *oauth2_generate_state(void);
/* we generate something like a guid, but not care about
 * anything, but that it is really random.
 */
char *oauth2_generate_state(void)
{
  char rv[37];
  int i;

  rv[0] = '\0';
  for(i = 0; i < 4; i++)
     sprintf(rv + strlen(rv), "%x", (unsigned int) (random() % 256));
  sprintf(rv + strlen(rv), "%c", '-');
  for(i = 0; i < 2; i++)
     sprintf(rv + strlen(rv), "%x", (unsigned int) (random() % 256));
  sprintf(rv + strlen(rv), "%c", '-');
  for(i = 0; i < 2; i++)
     sprintf(rv + strlen(rv), "%x", (unsigned int) (random() % 256));
  sprintf(rv + strlen(rv), "%c", '-');
  for(i = 0; i < 2; i++)
     sprintf(rv + strlen(rv), "%x", (unsigned int) (random() % 256));
  sprintf(rv + strlen(rv), "%c", '-');
  for(i = 0; i < 6; i++)
     sprintf(rv + strlen(rv), "%x", (unsigned int) (random() % 256));
  rv[36] = '\0';
  return cpystr(rv);
}
#endif /* OAUTH2_GENERATE_STATE */



/* 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();

    /* 
     * 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))))
         mm_login_method (mb, user, (void *) &oauth2, *trial, OA2NAME);
    }

    /* 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 = LONGT;		/* will get a BAD response back */
    }
    else {
      unsigned long rlen = strlen(OAUTH2_USER) + strlen(user)
			+ strlen(OAUTH2_BEARER) + strlen(oauth2.access_token) + 1 + 2;
      char *response = (char *) fs_get (rlen);
      char *t = response;	/* copy authorization id */
      for (u = OAUTH2_USER; *u; *t++ = *u++);
      for (u = user; *u; *t++ = *u++);
      *t++ = '\001';		/* delimiting ^A */
      for (u = OAUTH2_BEARER; *u; *t++ = *u++);
      for (u = oauth2.access_token; *u; *t++ = *u++);
      *t++ = '\001';		/* delimiting ^A */
      *t++ = '\001';		/* delimiting ^A */
      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){
	     if(oauth2.param[OA2_State].value)
		fs_give((void **) &oauth2.param[OA2_State].value);
	     fs_give((void **) &oauth2.param[OA2_RefreshToken].value);
	     fs_give((void **) &oauth2.access_token);
	     oauth2.expiration = 0L;
	  }
	}
      }
      fs_give ((void **) &response);
    }
  }
  if (!ret || !oauth2.name)
      *trial = 65535; 			/* don't retry if bad protocol */
  return ret;
}

#ifndef HTTP_OAUTH2_INCLUDED
#define HTTP_OAUTH2_INCLUDED
/* 
 * The code above is enough to implement XOAUTH2, all one needs is the username
 * and access token and give it to the function above. However, normal users cannot
 * be expected to get the access token, so we ask the client to help with getting 
 * the access token, refresh token and expire values, so the code below is written
 * to help with that.
 */

#include "http.h"
#include "json.h"

void 
mm_login_oauth2_c_client_method (NETMBX *mb, char *user, char *method,
			OAUTH2_S *oauth2, unsigned long trial, int *tryanother)
{
   int i;
   HTTP_PARAM_S params[OAUTH2_PARAM_NUMBER];
   OAUTH2_SERVER_METHOD_S RefreshMethod;
   char *s = NULL;
   JSON_S *json = NULL;

   if(oauth2->param[OA2_Id].value == NULL || oauth2->param[OA2_Secret].value == NULL){
     oauth2clientinfo_t ogci =
		(oauth2clientinfo_t) mail_parameters (NIL, GET_OA2CLIENTINFO, NIL);

     if(ogci) (*ogci)(oauth2->name, &oauth2->param[OA2_Id].value,
				&oauth2->param[OA2_Secret].value);
   }

   if(oauth2->param[OA2_Id].value == NULL || oauth2->param[OA2_Secret].value == NULL)
      return;

   /* first check if we have a refresh token, and in that case use it */
   if(oauth2->param[OA2_RefreshToken].value){

     RefreshMethod = oauth2->server_mthd[OA2_GetAccessTokenFromRefreshToken];
     for(i = 0; RefreshMethod.params[i] != OA2_End; i++){
	OA2_type j = RefreshMethod.params[i];
	params[i].name  = oauth2->param[j].name;
	params[i].value = oauth2->param[j].value;
     }
     params[i].name = params[i].value = NULL;

     if(strcmp(RefreshMethod.name, "POST") == 0)
	s = http_post_param(RefreshMethod.urlserver, params);
     else if(strcmp(RefreshMethod.name, "POST2") == 0)
	s = http_post_param2(RefreshMethod.urlserver, params);

     if(s){
	unsigned char *t, *u;
	if((t = strstr(s, "\r\n\r\n")) && (u = strchr(t, '{')))
	   json = json_parse(&u);
	fs_give((void **) &s);
     }

     if(json != NULL){
	JSON_X *jx;

	jx = json_body_value(json, "access_token");
	if(jx && jx->jtype == JString)
	   oauth2->access_token = cpystr((char *) jx->value);

	jx = json_body_value(json, "expires_in");
	if(jx){
	   if(jx->jtype == JString){
	      unsigned long *l = fs_get(sizeof(unsigned long));
	      *l = atol((char *) jx->value);
	      fs_give(&jx->value);
	      jx->value = (void *) l;
	      jx->jtype = JLong;
	   }
	   if(jx->jtype == JLong)
	      oauth2->expiration   = time(0) + *(unsigned long *) jx->value;
	}

	json_free(&json);
     }
     return;
   }
   /* 
    * else, we do not have a refresh token, nor an access token.
    * We need to start the process to get an access code. We use this
    * to get an access token and refresh token.
    */
   { 
     RefreshMethod = oauth2->server_mthd[OA2_GetAccessCode];
     for(i = 0; RefreshMethod.params[i] != OA2_End; i++){
	OA2_type j = RefreshMethod.params[i];
	params[i].name  = oauth2->param[j].name;
	params[i].value = oauth2->param[j].value;
     }
     params[i].name = params[i].value = NULL;

     if(strcmp(RefreshMethod.name, "GET") == 0){
	char *url = http_get_param_url(RefreshMethod.urlserver, params);
	oauth2getaccesscode_t ogac = 
	(oauth2getaccesscode_t) mail_parameters (NIL, GET_OA2CLIENTGETACCESSCODE, NIL);

	if(ogac)
	  oauth2->param[OA2_Code].value = (*ogac)(url, method, oauth2, tryanother);
     }

     if(oauth2->param[OA2_Code].value){
        RefreshMethod = oauth2->server_mthd[OA2_GetAccessTokenFromAccessCode];
        for(i = 0; RefreshMethod.params[i] != OA2_End; i++){
	   OA2_type j = RefreshMethod.params[i];
	   params[i].name  = oauth2->param[j].name;
	   params[i].value = oauth2->param[j].value;
        }
        params[i].name = params[i].value = NULL;

        if(strcmp(RefreshMethod.name, "POST") == 0)
	   s = http_post_param(RefreshMethod.urlserver, params);
	else if(strcmp(RefreshMethod.name, "POST2") == 0)
	   s = http_post_param2(RefreshMethod.urlserver, params);

        if(s){
	   unsigned char *t, *u;
	   if((t = strstr(s, "\r\n\r\n")) && (u = strchr(t, '{')))
		json = json_parse(&u);
	   fs_give((void **) &s);
        }

	if(json != NULL){
	   JSON_X *jx;

	   jx = json_body_value(json, "refresh_token");
	   if(jx && jx->jtype == JString)
	      oauth2->param[OA2_RefreshToken].value = cpystr((char *) jx->value);

	   jx = json_body_value(json, "access_token");
	   if(jx && jx->jtype == JString)
	      oauth2->access_token = cpystr((char *) jx->value);

	   jx = json_body_value(json, "expires_in");
	   if(jx){
	      if(jx->jtype == JString){
		unsigned long *l = fs_get(sizeof(unsigned long));
		*l = atol((char *) jx->value);
		fs_give(&jx->value);
		jx->value = (void *) l;
		jx->jtype = JLong;
	      }
	      if(jx->jtype == JLong)
	         oauth2->expiration = time(0) + *(unsigned long *) jx->value;
	   }
	   json_free(&json);
	}
     }
     return;
   }
}
#endif /* HTTP_OAUTH2_INCLUDED */