2 * RADIUS message processing
3 * Copyright (c) 2002-2009, 2011-2015, Jouni Malinen <j@w1.fi>
5 * This software may be distributed under the terms of the BSD license.
6 * See README for more details.
9 #include "utils/includes.h"
11 #include "utils/common.h"
12 #include "utils/wpabuf.h"
13 #include "crypto/md5.h"
14 #include "crypto/crypto.h"
19 * struct radius_msg - RADIUS message structure for new and parsed messages
23 * buf - Allocated buffer for RADIUS message
28 * hdr - Pointer to the RADIUS header in buf
30 struct radius_hdr *hdr;
33 * attr_pos - Array of indexes to attributes
35 * The values are number of bytes from buf to the beginning of
36 * struct radius_attr_hdr.
41 * attr_size - Total size of the attribute pointer array
46 * attr_used - Total number of attributes in the array
52 struct radius_hdr * radius_msg_get_hdr(struct radius_msg *msg)
58 struct wpabuf * radius_msg_get_buf(struct radius_msg *msg)
64 static struct radius_attr_hdr *
65 radius_get_attr_hdr(struct radius_msg *msg, int idx)
67 return (struct radius_attr_hdr *)
68 (wpabuf_mhead_u8(msg->buf) + msg->attr_pos[idx]);
72 static void radius_msg_set_hdr(struct radius_msg *msg, u8 code, u8 identifier)
74 msg->hdr->code = code;
75 msg->hdr->identifier = identifier;
79 static int radius_msg_initialize(struct radius_msg *msg)
81 msg->attr_pos = os_calloc(RADIUS_DEFAULT_ATTR_COUNT,
82 sizeof(*msg->attr_pos));
83 if (msg->attr_pos == NULL)
86 msg->attr_size = RADIUS_DEFAULT_ATTR_COUNT;
94 * radius_msg_new - Create a new RADIUS message
95 * @code: Code for RADIUS header
96 * @identifier: Identifier for RADIUS header
97 * Returns: Context for RADIUS message or %NULL on failure
99 * The caller is responsible for freeing the returned data with
102 struct radius_msg * radius_msg_new(u8 code, u8 identifier)
104 struct radius_msg *msg;
106 msg = os_zalloc(sizeof(*msg));
110 msg->buf = wpabuf_alloc(RADIUS_DEFAULT_MSG_SIZE);
111 if (msg->buf == NULL || radius_msg_initialize(msg)) {
112 radius_msg_free(msg);
115 msg->hdr = wpabuf_put(msg->buf, sizeof(struct radius_hdr));
117 radius_msg_set_hdr(msg, code, identifier);
124 * radius_msg_free - Free a RADIUS message
125 * @msg: RADIUS message from radius_msg_new() or radius_msg_parse()
127 void radius_msg_free(struct radius_msg *msg)
132 wpabuf_free(msg->buf);
133 os_free(msg->attr_pos);
138 static const char *radius_code_string(u8 code)
141 case RADIUS_CODE_ACCESS_REQUEST: return "Access-Request";
142 case RADIUS_CODE_ACCESS_ACCEPT: return "Access-Accept";
143 case RADIUS_CODE_ACCESS_REJECT: return "Access-Reject";
144 case RADIUS_CODE_ACCOUNTING_REQUEST: return "Accounting-Request";
145 case RADIUS_CODE_ACCOUNTING_RESPONSE: return "Accounting-Response";
146 case RADIUS_CODE_ACCESS_CHALLENGE: return "Access-Challenge";
147 case RADIUS_CODE_STATUS_SERVER: return "Status-Server";
148 case RADIUS_CODE_STATUS_CLIENT: return "Status-Client";
149 case RADIUS_CODE_RESERVED: return "Reserved";
150 case RADIUS_CODE_DISCONNECT_REQUEST: return "Disconnect-Request";
151 case RADIUS_CODE_DISCONNECT_ACK: return "Disconnect-ACK";
152 case RADIUS_CODE_DISCONNECT_NAK: return "Disconnect-NAK";
153 case RADIUS_CODE_COA_REQUEST: return "CoA-Request";
154 case RADIUS_CODE_COA_ACK: return "CoA-ACK";
155 case RADIUS_CODE_COA_NAK: return "CoA-NAK";
156 default: return "?Unknown?";
161 struct radius_attr_type {
165 RADIUS_ATTR_UNDIST, RADIUS_ATTR_TEXT, RADIUS_ATTR_IP,
166 RADIUS_ATTR_HEXDUMP, RADIUS_ATTR_INT32, RADIUS_ATTR_IPV6
170 static const struct radius_attr_type radius_attrs[] =
172 { RADIUS_ATTR_USER_NAME, "User-Name", RADIUS_ATTR_TEXT },
173 { RADIUS_ATTR_USER_PASSWORD, "User-Password", RADIUS_ATTR_UNDIST },
174 { RADIUS_ATTR_NAS_IP_ADDRESS, "NAS-IP-Address", RADIUS_ATTR_IP },
175 { RADIUS_ATTR_NAS_PORT, "NAS-Port", RADIUS_ATTR_INT32 },
176 { RADIUS_ATTR_SERVICE_TYPE, "Service-Type", RADIUS_ATTR_INT32 },
177 { RADIUS_ATTR_FRAMED_IP_ADDRESS, "Framed-IP-Address", RADIUS_ATTR_IP },
178 { RADIUS_ATTR_FRAMED_MTU, "Framed-MTU", RADIUS_ATTR_INT32 },
179 { RADIUS_ATTR_REPLY_MESSAGE, "Reply-Message", RADIUS_ATTR_TEXT },
180 { RADIUS_ATTR_STATE, "State", RADIUS_ATTR_UNDIST },
181 { RADIUS_ATTR_CLASS, "Class", RADIUS_ATTR_UNDIST },
182 { RADIUS_ATTR_VENDOR_SPECIFIC, "Vendor-Specific", RADIUS_ATTR_UNDIST },
183 { RADIUS_ATTR_SESSION_TIMEOUT, "Session-Timeout", RADIUS_ATTR_INT32 },
184 { RADIUS_ATTR_IDLE_TIMEOUT, "Idle-Timeout", RADIUS_ATTR_INT32 },
185 { RADIUS_ATTR_TERMINATION_ACTION, "Termination-Action",
187 { RADIUS_ATTR_CALLED_STATION_ID, "Called-Station-Id",
189 { RADIUS_ATTR_CALLING_STATION_ID, "Calling-Station-Id",
191 { RADIUS_ATTR_NAS_IDENTIFIER, "NAS-Identifier", RADIUS_ATTR_TEXT },
192 { RADIUS_ATTR_PROXY_STATE, "Proxy-State", RADIUS_ATTR_UNDIST },
193 { RADIUS_ATTR_ACCT_STATUS_TYPE, "Acct-Status-Type",
195 { RADIUS_ATTR_ACCT_DELAY_TIME, "Acct-Delay-Time", RADIUS_ATTR_INT32 },
196 { RADIUS_ATTR_ACCT_INPUT_OCTETS, "Acct-Input-Octets",
198 { RADIUS_ATTR_ACCT_OUTPUT_OCTETS, "Acct-Output-Octets",
200 { RADIUS_ATTR_ACCT_SESSION_ID, "Acct-Session-Id", RADIUS_ATTR_TEXT },
201 { RADIUS_ATTR_ACCT_AUTHENTIC, "Acct-Authentic", RADIUS_ATTR_INT32 },
202 { RADIUS_ATTR_ACCT_SESSION_TIME, "Acct-Session-Time",
204 { RADIUS_ATTR_ACCT_INPUT_PACKETS, "Acct-Input-Packets",
206 { RADIUS_ATTR_ACCT_OUTPUT_PACKETS, "Acct-Output-Packets",
208 { RADIUS_ATTR_ACCT_TERMINATE_CAUSE, "Acct-Terminate-Cause",
210 { RADIUS_ATTR_ACCT_MULTI_SESSION_ID, "Acct-Multi-Session-Id",
212 { RADIUS_ATTR_ACCT_LINK_COUNT, "Acct-Link-Count", RADIUS_ATTR_INT32 },
213 { RADIUS_ATTR_ACCT_INPUT_GIGAWORDS, "Acct-Input-Gigawords",
215 { RADIUS_ATTR_ACCT_OUTPUT_GIGAWORDS, "Acct-Output-Gigawords",
217 { RADIUS_ATTR_EVENT_TIMESTAMP, "Event-Timestamp",
219 { RADIUS_ATTR_EGRESS_VLANID, "EGRESS-VLANID", RADIUS_ATTR_HEXDUMP },
220 { RADIUS_ATTR_NAS_PORT_TYPE, "NAS-Port-Type", RADIUS_ATTR_INT32 },
221 { RADIUS_ATTR_TUNNEL_TYPE, "Tunnel-Type", RADIUS_ATTR_HEXDUMP },
222 { RADIUS_ATTR_TUNNEL_MEDIUM_TYPE, "Tunnel-Medium-Type",
223 RADIUS_ATTR_HEXDUMP },
224 { RADIUS_ATTR_TUNNEL_PASSWORD, "Tunnel-Password",
225 RADIUS_ATTR_UNDIST },
226 { RADIUS_ATTR_CONNECT_INFO, "Connect-Info", RADIUS_ATTR_TEXT },
227 { RADIUS_ATTR_EAP_MESSAGE, "EAP-Message", RADIUS_ATTR_UNDIST },
228 { RADIUS_ATTR_MESSAGE_AUTHENTICATOR, "Message-Authenticator",
229 RADIUS_ATTR_UNDIST },
230 { RADIUS_ATTR_TUNNEL_PRIVATE_GROUP_ID, "Tunnel-Private-Group-Id",
231 RADIUS_ATTR_HEXDUMP },
232 { RADIUS_ATTR_ACCT_INTERIM_INTERVAL, "Acct-Interim-Interval",
234 { RADIUS_ATTR_CHARGEABLE_USER_IDENTITY, "Chargeable-User-Identity",
236 { RADIUS_ATTR_NAS_IPV6_ADDRESS, "NAS-IPv6-Address", RADIUS_ATTR_IPV6 },
237 { RADIUS_ATTR_ERROR_CAUSE, "Error-Cause", RADIUS_ATTR_INT32 },
238 { RADIUS_ATTR_EAP_KEY_NAME, "EAP-Key-Name", RADIUS_ATTR_HEXDUMP },
239 { RADIUS_ATTR_OPERATOR_NAME, "Operator-Name", RADIUS_ATTR_TEXT },
240 { RADIUS_ATTR_LOCATION_INFO, "Location-Information",
241 RADIUS_ATTR_HEXDUMP },
242 { RADIUS_ATTR_LOCATION_DATA, "Location-Data", RADIUS_ATTR_HEXDUMP },
243 { RADIUS_ATTR_BASIC_LOCATION_POLICY_RULES,
244 "Basic-Location-Policy-Rules", RADIUS_ATTR_HEXDUMP },
245 { RADIUS_ATTR_EXTENDED_LOCATION_POLICY_RULES,
246 "Extended-Location-Policy-Rules", RADIUS_ATTR_HEXDUMP },
247 { RADIUS_ATTR_LOCATION_CAPABLE, "Location-Capable", RADIUS_ATTR_INT32 },
248 { RADIUS_ATTR_REQUESTED_LOCATION_INFO, "Requested-Location-Info",
250 { RADIUS_ATTR_MOBILITY_DOMAIN_ID, "Mobility-Domain-Id",
252 { RADIUS_ATTR_WLAN_HESSID, "WLAN-HESSID", RADIUS_ATTR_TEXT },
253 { RADIUS_ATTR_WLAN_PAIRWISE_CIPHER, "WLAN-Pairwise-Cipher",
254 RADIUS_ATTR_HEXDUMP },
255 { RADIUS_ATTR_WLAN_GROUP_CIPHER, "WLAN-Group-Cipher",
256 RADIUS_ATTR_HEXDUMP },
257 { RADIUS_ATTR_WLAN_AKM_SUITE, "WLAN-AKM-Suite",
258 RADIUS_ATTR_HEXDUMP },
259 { RADIUS_ATTR_WLAN_GROUP_MGMT_CIPHER, "WLAN-Group-Mgmt-Pairwise-Cipher",
260 RADIUS_ATTR_HEXDUMP },
262 #define RADIUS_ATTRS ARRAY_SIZE(radius_attrs)
265 static const struct radius_attr_type *radius_get_attr_type(u8 type)
269 for (i = 0; i < RADIUS_ATTRS; i++) {
270 if (type == radius_attrs[i].type)
271 return &radius_attrs[i];
278 static void radius_msg_dump_attr(struct radius_attr_hdr *hdr)
280 const struct radius_attr_type *attr;
285 attr = radius_get_attr_type(hdr->type);
287 wpa_printf(MSG_INFO, " Attribute %d (%s) length=%d",
288 hdr->type, attr ? attr->name : "?Unknown?", hdr->length);
290 if (attr == NULL || hdr->length < sizeof(struct radius_attr_hdr))
293 len = hdr->length - sizeof(struct radius_attr_hdr);
294 pos = (unsigned char *) (hdr + 1);
296 switch (attr->data_type) {
297 case RADIUS_ATTR_TEXT:
298 printf_encode(buf, sizeof(buf), pos, len);
299 wpa_printf(MSG_INFO, " Value: '%s'", buf);
305 os_memcpy(&addr, pos, 4);
306 wpa_printf(MSG_INFO, " Value: %s",
309 wpa_printf(MSG_INFO, " Invalid IP address length %d",
315 case RADIUS_ATTR_IPV6:
318 struct in6_addr *addr = (struct in6_addr *) pos;
319 atxt = inet_ntop(AF_INET6, addr, buf, sizeof(buf));
320 wpa_printf(MSG_INFO, " Value: %s",
323 wpa_printf(MSG_INFO, " Invalid IPv6 address length %d",
327 #endif /* CONFIG_IPV6 */
329 case RADIUS_ATTR_HEXDUMP:
330 case RADIUS_ATTR_UNDIST:
331 wpa_snprintf_hex(buf, sizeof(buf), pos, len);
332 wpa_printf(MSG_INFO, " Value: %s", buf);
335 case RADIUS_ATTR_INT32:
337 wpa_printf(MSG_INFO, " Value: %u",
340 wpa_printf(MSG_INFO, " Invalid INT32 length %d",
350 void radius_msg_dump(struct radius_msg *msg)
354 wpa_printf(MSG_INFO, "RADIUS message: code=%d (%s) identifier=%d length=%d",
355 msg->hdr->code, radius_code_string(msg->hdr->code),
356 msg->hdr->identifier, be_to_host16(msg->hdr->length));
358 for (i = 0; i < msg->attr_used; i++) {
359 struct radius_attr_hdr *attr = radius_get_attr_hdr(msg, i);
360 radius_msg_dump_attr(attr);
365 int radius_msg_finish(struct radius_msg *msg, const u8 *secret,
369 u8 auth[MD5_MAC_LEN];
370 struct radius_attr_hdr *attr;
372 os_memset(auth, 0, MD5_MAC_LEN);
373 attr = radius_msg_add_attr(msg,
374 RADIUS_ATTR_MESSAGE_AUTHENTICATOR,
377 wpa_printf(MSG_WARNING, "RADIUS: Could not add "
378 "Message-Authenticator");
381 msg->hdr->length = host_to_be16(wpabuf_len(msg->buf));
382 hmac_md5(secret, secret_len, wpabuf_head(msg->buf),
383 wpabuf_len(msg->buf), (u8 *) (attr + 1));
385 msg->hdr->length = host_to_be16(wpabuf_len(msg->buf));
387 if (wpabuf_len(msg->buf) > 0xffff) {
388 wpa_printf(MSG_WARNING, "RADIUS: Too long message (%lu)",
389 (unsigned long) wpabuf_len(msg->buf));
396 int radius_msg_finish_srv(struct radius_msg *msg, const u8 *secret,
397 size_t secret_len, const u8 *req_authenticator)
399 u8 auth[MD5_MAC_LEN];
400 struct radius_attr_hdr *attr;
404 os_memset(auth, 0, MD5_MAC_LEN);
405 attr = radius_msg_add_attr(msg, RADIUS_ATTR_MESSAGE_AUTHENTICATOR,
408 wpa_printf(MSG_ERROR, "WARNING: Could not add Message-Authenticator");
411 msg->hdr->length = host_to_be16(wpabuf_len(msg->buf));
412 os_memcpy(msg->hdr->authenticator, req_authenticator,
413 sizeof(msg->hdr->authenticator));
414 hmac_md5(secret, secret_len, wpabuf_head(msg->buf),
415 wpabuf_len(msg->buf), (u8 *) (attr + 1));
417 /* ResponseAuth = MD5(Code+ID+Length+RequestAuth+Attributes+Secret) */
418 addr[0] = (u8 *) msg->hdr;
420 addr[1] = req_authenticator;
421 len[1] = MD5_MAC_LEN;
422 addr[2] = wpabuf_head_u8(msg->buf) + sizeof(struct radius_hdr);
423 len[2] = wpabuf_len(msg->buf) - sizeof(struct radius_hdr);
426 md5_vector(4, addr, len, msg->hdr->authenticator);
428 if (wpabuf_len(msg->buf) > 0xffff) {
429 wpa_printf(MSG_WARNING, "RADIUS: Too long message (%lu)",
430 (unsigned long) wpabuf_len(msg->buf));
437 int radius_msg_finish_das_resp(struct radius_msg *msg, const u8 *secret,
439 const struct radius_hdr *req_hdr)
443 u8 auth[MD5_MAC_LEN];
444 struct radius_attr_hdr *attr;
446 os_memset(auth, 0, MD5_MAC_LEN);
447 attr = radius_msg_add_attr(msg, RADIUS_ATTR_MESSAGE_AUTHENTICATOR,
450 wpa_printf(MSG_WARNING, "Could not add Message-Authenticator");
454 msg->hdr->length = host_to_be16(wpabuf_len(msg->buf));
455 os_memcpy(msg->hdr->authenticator, req_hdr->authenticator, 16);
456 hmac_md5(secret, secret_len, wpabuf_head(msg->buf),
457 wpabuf_len(msg->buf), (u8 *) (attr + 1));
459 /* ResponseAuth = MD5(Code+ID+Length+RequestAuth+Attributes+Secret) */
460 addr[0] = wpabuf_head_u8(msg->buf);
461 len[0] = wpabuf_len(msg->buf);
464 if (md5_vector(2, addr, len, msg->hdr->authenticator) < 0)
467 if (wpabuf_len(msg->buf) > 0xffff) {
468 wpa_printf(MSG_WARNING, "RADIUS: Too long message (%lu)",
469 (unsigned long) wpabuf_len(msg->buf));
476 void radius_msg_finish_acct(struct radius_msg *msg, const u8 *secret,
482 msg->hdr->length = host_to_be16(wpabuf_len(msg->buf));
483 os_memset(msg->hdr->authenticator, 0, MD5_MAC_LEN);
484 addr[0] = wpabuf_head(msg->buf);
485 len[0] = wpabuf_len(msg->buf);
488 md5_vector(2, addr, len, msg->hdr->authenticator);
490 if (wpabuf_len(msg->buf) > 0xffff) {
491 wpa_printf(MSG_WARNING, "RADIUS: Too long messages (%lu)",
492 (unsigned long) wpabuf_len(msg->buf));
497 void radius_msg_finish_acct_resp(struct radius_msg *msg, const u8 *secret,
498 size_t secret_len, const u8 *req_authenticator)
503 msg->hdr->length = host_to_be16(wpabuf_len(msg->buf));
504 os_memcpy(msg->hdr->authenticator, req_authenticator, MD5_MAC_LEN);
505 addr[0] = wpabuf_head(msg->buf);
506 len[0] = wpabuf_len(msg->buf);
509 md5_vector(2, addr, len, msg->hdr->authenticator);
511 if (wpabuf_len(msg->buf) > 0xffff) {
512 wpa_printf(MSG_WARNING, "RADIUS: Too long messages (%lu)",
513 (unsigned long) wpabuf_len(msg->buf));
518 int radius_msg_verify_acct_req(struct radius_msg *msg, const u8 *secret,
523 u8 zero[MD5_MAC_LEN];
524 u8 hash[MD5_MAC_LEN];
526 os_memset(zero, 0, sizeof(zero));
527 addr[0] = (u8 *) msg->hdr;
528 len[0] = sizeof(struct radius_hdr) - MD5_MAC_LEN;
530 len[1] = MD5_MAC_LEN;
531 addr[2] = (u8 *) (msg->hdr + 1);
532 len[2] = wpabuf_len(msg->buf) - sizeof(struct radius_hdr);
535 md5_vector(4, addr, len, hash);
536 return os_memcmp_const(msg->hdr->authenticator, hash, MD5_MAC_LEN) != 0;
540 int radius_msg_verify_das_req(struct radius_msg *msg, const u8 *secret,
542 int require_message_authenticator)
546 u8 zero[MD5_MAC_LEN];
547 u8 hash[MD5_MAC_LEN];
548 u8 auth[MD5_MAC_LEN], orig[MD5_MAC_LEN];
549 u8 orig_authenticator[16];
551 struct radius_attr_hdr *attr = NULL, *tmp;
554 os_memset(zero, 0, sizeof(zero));
555 addr[0] = (u8 *) msg->hdr;
556 len[0] = sizeof(struct radius_hdr) - MD5_MAC_LEN;
558 len[1] = MD5_MAC_LEN;
559 addr[2] = (u8 *) (msg->hdr + 1);
560 len[2] = wpabuf_len(msg->buf) - sizeof(struct radius_hdr);
563 md5_vector(4, addr, len, hash);
564 if (os_memcmp_const(msg->hdr->authenticator, hash, MD5_MAC_LEN) != 0)
567 for (i = 0; i < msg->attr_used; i++) {
568 tmp = radius_get_attr_hdr(msg, i);
569 if (tmp->type == RADIUS_ATTR_MESSAGE_AUTHENTICATOR) {
571 wpa_printf(MSG_WARNING, "Multiple "
572 "Message-Authenticator attributes "
573 "in RADIUS message");
581 if (require_message_authenticator) {
582 wpa_printf(MSG_WARNING,
583 "Missing Message-Authenticator attribute in RADIUS message");
589 os_memcpy(orig, attr + 1, MD5_MAC_LEN);
590 os_memset(attr + 1, 0, MD5_MAC_LEN);
591 os_memcpy(orig_authenticator, msg->hdr->authenticator,
592 sizeof(orig_authenticator));
593 os_memset(msg->hdr->authenticator, 0,
594 sizeof(msg->hdr->authenticator));
595 hmac_md5(secret, secret_len, wpabuf_head(msg->buf),
596 wpabuf_len(msg->buf), auth);
597 os_memcpy(attr + 1, orig, MD5_MAC_LEN);
598 os_memcpy(msg->hdr->authenticator, orig_authenticator,
599 sizeof(orig_authenticator));
601 return os_memcmp_const(orig, auth, MD5_MAC_LEN) != 0;
605 static int radius_msg_add_attr_to_array(struct radius_msg *msg,
606 struct radius_attr_hdr *attr)
608 if (msg->attr_used >= msg->attr_size) {
610 int nlen = msg->attr_size * 2;
612 nattr_pos = os_realloc_array(msg->attr_pos, nlen,
613 sizeof(*msg->attr_pos));
614 if (nattr_pos == NULL)
617 msg->attr_pos = nattr_pos;
618 msg->attr_size = nlen;
621 msg->attr_pos[msg->attr_used++] =
622 (unsigned char *) attr - wpabuf_head_u8(msg->buf);
628 struct radius_attr_hdr *radius_msg_add_attr(struct radius_msg *msg, u8 type,
629 const u8 *data, size_t data_len)
632 struct radius_attr_hdr *attr;
634 if (data_len > RADIUS_MAX_ATTR_LEN) {
635 wpa_printf(MSG_ERROR, "radius_msg_add_attr: too long attribute (%lu bytes)",
636 (unsigned long) data_len);
640 buf_needed = sizeof(*attr) + data_len;
642 if (wpabuf_tailroom(msg->buf) < buf_needed) {
643 /* allocate more space for message buffer */
644 if (wpabuf_resize(&msg->buf, buf_needed) < 0)
646 msg->hdr = wpabuf_mhead(msg->buf);
649 attr = wpabuf_put(msg->buf, sizeof(struct radius_attr_hdr));
651 attr->length = sizeof(*attr) + data_len;
652 wpabuf_put_data(msg->buf, data, data_len);
654 if (radius_msg_add_attr_to_array(msg, attr))
662 * radius_msg_parse - Parse a RADIUS message
663 * @data: RADIUS message to be parsed
664 * @len: Length of data buffer in octets
665 * Returns: Parsed RADIUS message or %NULL on failure
667 * This parses a RADIUS message and makes a copy of its data. The caller is
668 * responsible for freeing the returned data with radius_msg_free().
670 struct radius_msg * radius_msg_parse(const u8 *data, size_t len)
672 struct radius_msg *msg;
673 struct radius_hdr *hdr;
674 struct radius_attr_hdr *attr;
676 unsigned char *pos, *end;
678 if (data == NULL || len < sizeof(*hdr))
681 hdr = (struct radius_hdr *) data;
683 msg_len = be_to_host16(hdr->length);
684 if (msg_len < sizeof(*hdr) || msg_len > len) {
685 wpa_printf(MSG_INFO, "RADIUS: Invalid message length");
690 wpa_printf(MSG_DEBUG, "RADIUS: Ignored %lu extra bytes after "
691 "RADIUS message", (unsigned long) len - msg_len);
694 msg = os_zalloc(sizeof(*msg));
698 msg->buf = wpabuf_alloc_copy(data, msg_len);
699 if (msg->buf == NULL || radius_msg_initialize(msg)) {
700 radius_msg_free(msg);
703 msg->hdr = wpabuf_mhead(msg->buf);
705 /* parse attributes */
706 pos = wpabuf_mhead_u8(msg->buf) + sizeof(struct radius_hdr);
707 end = wpabuf_mhead_u8(msg->buf) + wpabuf_len(msg->buf);
709 if ((size_t) (end - pos) < sizeof(*attr))
712 attr = (struct radius_attr_hdr *) pos;
714 if (attr->length > end - pos || attr->length < sizeof(*attr))
717 /* TODO: check that attr->length is suitable for attr->type */
719 if (radius_msg_add_attr_to_array(msg, attr))
728 radius_msg_free(msg);
733 int radius_msg_add_eap(struct radius_msg *msg, const u8 *data, size_t data_len)
735 const u8 *pos = data;
736 size_t left = data_len;
740 if (left > RADIUS_MAX_ATTR_LEN)
741 len = RADIUS_MAX_ATTR_LEN;
745 if (!radius_msg_add_attr(msg, RADIUS_ATTR_EAP_MESSAGE,
757 struct wpabuf * radius_msg_get_eap(struct radius_msg *msg)
761 struct radius_attr_hdr *attr;
767 for (i = 0; i < msg->attr_used; i++) {
768 attr = radius_get_attr_hdr(msg, i);
769 if (attr->type == RADIUS_ATTR_EAP_MESSAGE &&
770 attr->length > sizeof(struct radius_attr_hdr))
771 len += attr->length - sizeof(struct radius_attr_hdr);
777 eap = wpabuf_alloc(len);
781 for (i = 0; i < msg->attr_used; i++) {
782 attr = radius_get_attr_hdr(msg, i);
783 if (attr->type == RADIUS_ATTR_EAP_MESSAGE &&
784 attr->length > sizeof(struct radius_attr_hdr)) {
785 int flen = attr->length - sizeof(*attr);
786 wpabuf_put_data(eap, attr + 1, flen);
794 int radius_msg_verify_msg_auth(struct radius_msg *msg, const u8 *secret,
795 size_t secret_len, const u8 *req_auth)
797 u8 auth[MD5_MAC_LEN], orig[MD5_MAC_LEN];
798 u8 orig_authenticator[16];
799 struct radius_attr_hdr *attr = NULL, *tmp;
802 for (i = 0; i < msg->attr_used; i++) {
803 tmp = radius_get_attr_hdr(msg, i);
804 if (tmp->type == RADIUS_ATTR_MESSAGE_AUTHENTICATOR) {
806 wpa_printf(MSG_INFO, "Multiple Message-Authenticator attributes in RADIUS message");
814 wpa_printf(MSG_INFO, "No Message-Authenticator attribute found");
818 os_memcpy(orig, attr + 1, MD5_MAC_LEN);
819 os_memset(attr + 1, 0, MD5_MAC_LEN);
821 os_memcpy(orig_authenticator, msg->hdr->authenticator,
822 sizeof(orig_authenticator));
823 os_memcpy(msg->hdr->authenticator, req_auth,
824 sizeof(msg->hdr->authenticator));
826 if (hmac_md5(secret, secret_len, wpabuf_head(msg->buf),
827 wpabuf_len(msg->buf), auth) < 0)
829 os_memcpy(attr + 1, orig, MD5_MAC_LEN);
831 os_memcpy(msg->hdr->authenticator, orig_authenticator,
832 sizeof(orig_authenticator));
835 if (os_memcmp_const(orig, auth, MD5_MAC_LEN) != 0) {
836 wpa_printf(MSG_INFO, "Invalid Message-Authenticator!");
844 int radius_msg_verify(struct radius_msg *msg, const u8 *secret,
845 size_t secret_len, struct radius_msg *sent_msg, int auth)
849 u8 hash[MD5_MAC_LEN];
851 if (sent_msg == NULL) {
852 wpa_printf(MSG_INFO, "No matching Access-Request message found");
857 radius_msg_verify_msg_auth(msg, secret, secret_len,
858 sent_msg->hdr->authenticator)) {
862 /* ResponseAuth = MD5(Code+ID+Length+RequestAuth+Attributes+Secret) */
863 addr[0] = (u8 *) msg->hdr;
865 addr[1] = sent_msg->hdr->authenticator;
866 len[1] = MD5_MAC_LEN;
867 addr[2] = wpabuf_head_u8(msg->buf) + sizeof(struct radius_hdr);
868 len[2] = wpabuf_len(msg->buf) - sizeof(struct radius_hdr);
871 if (md5_vector(4, addr, len, hash) < 0 ||
872 os_memcmp_const(hash, msg->hdr->authenticator, MD5_MAC_LEN) != 0) {
873 wpa_printf(MSG_INFO, "Response Authenticator invalid!");
881 int radius_msg_copy_attr(struct radius_msg *dst, struct radius_msg *src,
884 struct radius_attr_hdr *attr;
888 for (i = 0; i < src->attr_used; i++) {
889 attr = radius_get_attr_hdr(src, i);
890 if (attr->type == type && attr->length >= sizeof(*attr)) {
891 if (!radius_msg_add_attr(dst, type, (u8 *) (attr + 1),
892 attr->length - sizeof(*attr)))
902 /* Create Request Authenticator. The value should be unique over the lifetime
903 * of the shared secret between authenticator and authentication server.
905 int radius_msg_make_authenticator(struct radius_msg *msg)
907 return os_get_random((u8 *) &msg->hdr->authenticator,
908 sizeof(msg->hdr->authenticator));
912 /* Get Vendor-specific RADIUS Attribute from a parsed RADIUS message.
913 * Returns the Attribute payload and sets alen to indicate the length of the
914 * payload if a vendor attribute with subtype is found, otherwise returns NULL.
915 * The returned payload is allocated with os_malloc() and caller must free it
916 * by calling os_free().
918 static u8 *radius_msg_get_vendor_attr(struct radius_msg *msg, u32 vendor,
919 u8 subtype, size_t *alen)
927 for (i = 0; i < msg->attr_used; i++) {
928 struct radius_attr_hdr *attr = radius_get_attr_hdr(msg, i);
931 struct radius_attr_vendor *vhdr;
933 if (attr->type != RADIUS_ATTR_VENDOR_SPECIFIC ||
934 attr->length < sizeof(*attr))
937 left = attr->length - sizeof(*attr);
941 pos = (u8 *) (attr + 1);
943 os_memcpy(&vendor_id, pos, 4);
947 if (ntohl(vendor_id) != vendor)
950 while (left >= sizeof(*vhdr)) {
951 vhdr = (struct radius_attr_vendor *) pos;
952 if (vhdr->vendor_length > left ||
953 vhdr->vendor_length < sizeof(*vhdr)) {
956 if (vhdr->vendor_type != subtype) {
957 pos += vhdr->vendor_length;
958 left -= vhdr->vendor_length;
962 len = vhdr->vendor_length - sizeof(*vhdr);
963 data = os_malloc(len);
966 os_memcpy(data, pos + sizeof(*vhdr), len);
977 static u8 * decrypt_ms_key(const u8 *key, size_t len,
978 const u8 *req_authenticator,
979 const u8 *secret, size_t secret_len, size_t *reslen)
981 u8 *plain, *ppos, *res;
984 u8 hash[MD5_MAC_LEN];
989 /* key: 16-bit salt followed by encrypted key info */
992 wpa_printf(MSG_DEBUG, "RADIUS: %s: Len is too small: %d",
993 __func__, (int) len);
1000 wpa_printf(MSG_INFO, "RADIUS: Invalid ms key len %lu",
1001 (unsigned long) left);
1006 ppos = plain = os_malloc(plen);
1012 /* b(1) = MD5(Secret + Request-Authenticator + Salt)
1013 * b(i) = MD5(Secret + c(i - 1)) for i > 1 */
1016 elen[0] = secret_len;
1018 addr[1] = req_authenticator;
1019 elen[1] = MD5_MAC_LEN;
1021 elen[2] = 2; /* Salt */
1023 addr[1] = pos - MD5_MAC_LEN;
1024 elen[1] = MD5_MAC_LEN;
1026 if (md5_vector(first ? 3 : 2, addr, elen, hash) < 0) {
1032 for (i = 0; i < MD5_MAC_LEN; i++)
1033 *ppos++ = *pos++ ^ hash[i];
1034 left -= MD5_MAC_LEN;
1037 if (plain[0] == 0 || plain[0] > plen - 1) {
1038 wpa_printf(MSG_INFO, "RADIUS: Failed to decrypt MPPE key");
1043 res = os_malloc(plain[0]);
1048 os_memcpy(res, plain + 1, plain[0]);
1056 static void encrypt_ms_key(const u8 *key, size_t key_len, u16 salt,
1057 const u8 *req_authenticator,
1058 const u8 *secret, size_t secret_len,
1059 u8 *ebuf, size_t *elen)
1061 int i, len, first = 1;
1062 u8 hash[MD5_MAC_LEN], saltbuf[2], *pos;
1066 WPA_PUT_BE16(saltbuf, salt);
1070 len = (len & 0xf0) + 16;
1072 os_memset(ebuf, 0, len);
1074 os_memcpy(ebuf + 1, key, key_len);
1080 /* b(1) = MD5(Secret + Request-Authenticator + Salt)
1081 * b(i) = MD5(Secret + c(i - 1)) for i > 1 */
1083 _len[0] = secret_len;
1085 addr[1] = req_authenticator;
1086 _len[1] = MD5_MAC_LEN;
1088 _len[2] = sizeof(saltbuf);
1090 addr[1] = pos - MD5_MAC_LEN;
1091 _len[1] = MD5_MAC_LEN;
1093 md5_vector(first ? 3 : 2, addr, _len, hash);
1096 for (i = 0; i < MD5_MAC_LEN; i++)
1104 struct radius_ms_mppe_keys *
1105 radius_msg_get_ms_keys(struct radius_msg *msg, struct radius_msg *sent_msg,
1106 const u8 *secret, size_t secret_len)
1110 struct radius_ms_mppe_keys *keys;
1112 if (msg == NULL || sent_msg == NULL)
1115 keys = os_zalloc(sizeof(*keys));
1119 key = radius_msg_get_vendor_attr(msg, RADIUS_VENDOR_ID_MICROSOFT,
1120 RADIUS_VENDOR_ATTR_MS_MPPE_SEND_KEY,
1123 keys->send = decrypt_ms_key(key, keylen,
1124 sent_msg->hdr->authenticator,
1128 wpa_printf(MSG_DEBUG,
1129 "RADIUS: Failed to decrypt send key");
1134 key = radius_msg_get_vendor_attr(msg, RADIUS_VENDOR_ID_MICROSOFT,
1135 RADIUS_VENDOR_ATTR_MS_MPPE_RECV_KEY,
1138 keys->recv = decrypt_ms_key(key, keylen,
1139 sent_msg->hdr->authenticator,
1143 wpa_printf(MSG_DEBUG,
1144 "RADIUS: Failed to decrypt recv key");
1153 struct radius_ms_mppe_keys *
1154 radius_msg_get_cisco_keys(struct radius_msg *msg, struct radius_msg *sent_msg,
1155 const u8 *secret, size_t secret_len)
1159 struct radius_ms_mppe_keys *keys;
1161 if (msg == NULL || sent_msg == NULL)
1164 keys = os_zalloc(sizeof(*keys));
1168 key = radius_msg_get_vendor_attr(msg, RADIUS_VENDOR_ID_CISCO,
1169 RADIUS_CISCO_AV_PAIR, &keylen);
1170 if (key && keylen == 51 &&
1171 os_memcmp(key, "leap:session-key=", 17) == 0) {
1172 keys->recv = decrypt_ms_key(key + 17, keylen - 17,
1173 sent_msg->hdr->authenticator,
1183 int radius_msg_add_mppe_keys(struct radius_msg *msg,
1184 const u8 *req_authenticator,
1185 const u8 *secret, size_t secret_len,
1186 const u8 *send_key, size_t send_key_len,
1187 const u8 *recv_key, size_t recv_key_len)
1189 struct radius_attr_hdr *attr;
1190 u32 vendor_id = htonl(RADIUS_VENDOR_ID_MICROSOFT);
1192 struct radius_attr_vendor *vhdr;
1198 hlen = sizeof(vendor_id) + sizeof(*vhdr) + 2;
1200 /* MS-MPPE-Send-Key */
1201 buf = os_malloc(hlen + send_key_len + 16);
1206 os_memcpy(pos, &vendor_id, sizeof(vendor_id));
1207 pos += sizeof(vendor_id);
1208 vhdr = (struct radius_attr_vendor *) pos;
1209 vhdr->vendor_type = RADIUS_VENDOR_ATTR_MS_MPPE_SEND_KEY;
1210 pos = (u8 *) (vhdr + 1);
1211 if (os_get_random((u8 *) &salt, sizeof(salt)) < 0) {
1216 WPA_PUT_BE16(pos, salt);
1218 encrypt_ms_key(send_key, send_key_len, salt, req_authenticator, secret,
1219 secret_len, pos, &elen);
1220 vhdr->vendor_length = hlen + elen - sizeof(vendor_id);
1222 attr = radius_msg_add_attr(msg, RADIUS_ATTR_VENDOR_SPECIFIC,
1229 /* MS-MPPE-Recv-Key */
1230 buf = os_malloc(hlen + recv_key_len + 16);
1235 os_memcpy(pos, &vendor_id, sizeof(vendor_id));
1236 pos += sizeof(vendor_id);
1237 vhdr = (struct radius_attr_vendor *) pos;
1238 vhdr->vendor_type = RADIUS_VENDOR_ATTR_MS_MPPE_RECV_KEY;
1239 pos = (u8 *) (vhdr + 1);
1241 WPA_PUT_BE16(pos, salt);
1243 encrypt_ms_key(recv_key, recv_key_len, salt, req_authenticator, secret,
1244 secret_len, pos, &elen);
1245 vhdr->vendor_length = hlen + elen - sizeof(vendor_id);
1247 attr = radius_msg_add_attr(msg, RADIUS_ATTR_VENDOR_SPECIFIC,
1258 int radius_msg_add_wfa(struct radius_msg *msg, u8 subtype, const u8 *data,
1261 struct radius_attr_hdr *attr;
1266 buf = os_malloc(alen);
1270 WPA_PUT_BE32(pos, RADIUS_VENDOR_ID_WFA);
1274 os_memcpy(pos, data, len);
1275 attr = radius_msg_add_attr(msg, RADIUS_ATTR_VENDOR_SPECIFIC,
1285 int radius_user_password_hide(struct radius_msg *msg,
1286 const u8 *data, size_t data_len,
1287 const u8 *secret, size_t secret_len,
1288 u8 *buf, size_t buf_len)
1290 size_t padlen, i, pos;
1295 if (data_len + 16 > buf_len)
1298 os_memcpy(buf, data, data_len);
1300 padlen = data_len % 16;
1301 if (padlen && data_len < buf_len) {
1302 padlen = 16 - padlen;
1303 os_memset(buf + data_len, 0, padlen);
1304 buf_len = data_len + padlen;
1310 len[0] = secret_len;
1311 addr[1] = msg->hdr->authenticator;
1313 md5_vector(2, addr, len, hash);
1315 for (i = 0; i < 16; i++)
1319 while (pos < buf_len) {
1321 len[0] = secret_len;
1322 addr[1] = &buf[pos - 16];
1324 md5_vector(2, addr, len, hash);
1326 for (i = 0; i < 16; i++)
1327 buf[pos + i] ^= hash[i];
1336 /* Add User-Password attribute to a RADIUS message and encrypt it as specified
1337 * in RFC 2865, Chap. 5.2 */
1338 struct radius_attr_hdr *
1339 radius_msg_add_attr_user_password(struct radius_msg *msg,
1340 const u8 *data, size_t data_len,
1341 const u8 *secret, size_t secret_len)
1346 res = radius_user_password_hide(msg, data, data_len,
1347 secret, secret_len, buf, sizeof(buf));
1351 return radius_msg_add_attr(msg, RADIUS_ATTR_USER_PASSWORD,
1356 int radius_msg_get_attr(struct radius_msg *msg, u8 type, u8 *buf, size_t len)
1358 struct radius_attr_hdr *attr = NULL, *tmp;
1361 for (i = 0; i < msg->attr_used; i++) {
1362 tmp = radius_get_attr_hdr(msg, i);
1363 if (tmp->type == type) {
1369 if (!attr || attr->length < sizeof(*attr))
1372 dlen = attr->length - sizeof(*attr);
1374 os_memcpy(buf, (attr + 1), dlen > len ? len : dlen);
1379 int radius_msg_get_attr_ptr(struct radius_msg *msg, u8 type, u8 **buf,
1380 size_t *len, const u8 *start)
1383 struct radius_attr_hdr *attr = NULL, *tmp;
1385 for (i = 0; i < msg->attr_used; i++) {
1386 tmp = radius_get_attr_hdr(msg, i);
1387 if (tmp->type == type &&
1388 (start == NULL || (u8 *) tmp > start)) {
1394 if (!attr || attr->length < sizeof(*attr))
1397 *buf = (u8 *) (attr + 1);
1398 *len = attr->length - sizeof(*attr);
1403 int radius_msg_count_attr(struct radius_msg *msg, u8 type, int min_len)
1408 for (count = 0, i = 0; i < msg->attr_used; i++) {
1409 struct radius_attr_hdr *attr = radius_get_attr_hdr(msg, i);
1410 if (attr->type == type &&
1411 attr->length >= sizeof(struct radius_attr_hdr) + min_len)
1419 struct radius_tunnel_attrs {
1421 int type; /* Tunnel-Type */
1422 int medium_type; /* Tunnel-Medium-Type */
1427 static int cmp_int(const void *a, const void *b)
1438 * radius_msg_get_vlanid - Parse RADIUS attributes for VLAN tunnel information
1439 * The k tagged vlans found are sorted by vlan_id and stored in the first k
1442 * @msg: RADIUS message
1443 * @untagged: Pointer to store untagged vid
1444 * @numtagged: Size of tagged
1445 * @tagged: Pointer to store tagged list
1447 * Returns: 0 if neither tagged nor untagged configuration is found, 1 otherwise
1449 int radius_msg_get_vlanid(struct radius_msg *msg, int *untagged, int numtagged,
1452 struct radius_tunnel_attrs tunnel[RADIUS_TUNNEL_TAGS], *tun;
1454 struct radius_attr_hdr *attr = NULL;
1458 int j, taggedidx = 0, vlan_id;
1460 os_memset(&tunnel, 0, sizeof(tunnel));
1461 for (j = 0; j < numtagged; j++)
1465 for (i = 0; i < msg->attr_used; i++) {
1466 attr = radius_get_attr_hdr(msg, i);
1467 if (attr->length < sizeof(*attr))
1469 data = (const u8 *) (attr + 1);
1470 dlen = attr->length - sizeof(*attr);
1471 if (attr->length < 3)
1473 if (data[0] >= RADIUS_TUNNEL_TAGS)
1476 tun = &tunnel[data[0]];
1478 switch (attr->type) {
1479 case RADIUS_ATTR_TUNNEL_TYPE:
1480 if (attr->length != 6)
1483 tun->type = WPA_GET_BE24(data + 1);
1485 case RADIUS_ATTR_TUNNEL_MEDIUM_TYPE:
1486 if (attr->length != 6)
1489 tun->medium_type = WPA_GET_BE24(data + 1);
1491 case RADIUS_ATTR_TUNNEL_PRIVATE_GROUP_ID:
1492 if (data[0] < RADIUS_TUNNEL_TAGS) {
1496 if (dlen >= sizeof(buf))
1498 os_memcpy(buf, data, dlen);
1500 vlan_id = atoi(buf);
1504 tun->vlanid = vlan_id;
1506 case RADIUS_ATTR_EGRESS_VLANID: /* RFC 4675 */
1507 if (attr->length != 6)
1509 vlan_id = WPA_GET_BE24(data + 1);
1512 if (data[0] == 0x32)
1513 *untagged = vlan_id;
1514 else if (data[0] == 0x31 && tagged &&
1515 taggedidx < numtagged)
1516 tagged[taggedidx++] = vlan_id;
1521 /* Use tunnel with the lowest tag for untagged VLAN id */
1522 for (i = 0; i < RADIUS_TUNNEL_TAGS; i++) {
1524 if (tun->tag_used &&
1525 tun->type == RADIUS_TUNNEL_TYPE_VLAN &&
1526 tun->medium_type == RADIUS_TUNNEL_MEDIUM_TYPE_802 &&
1528 *untagged = tun->vlanid;
1534 qsort(tagged, taggedidx, sizeof(int), cmp_int);
1536 if (*untagged > 0 || taggedidx)
1543 * radius_msg_get_tunnel_password - Parse RADIUS attribute Tunnel-Password
1544 * @msg: Received RADIUS message
1545 * @keylen: Length of returned password
1546 * @secret: RADIUS shared secret
1547 * @secret_len: Length of secret
1548 * @sent_msg: Sent RADIUS message
1549 * @n: Number of password attribute to return (starting with 0)
1550 * Returns: Pointer to n-th password (free with os_free) or %NULL
1552 char * radius_msg_get_tunnel_password(struct radius_msg *msg, int *keylen,
1553 const u8 *secret, size_t secret_len,
1554 struct radius_msg *sent_msg, size_t n)
1565 struct radius_attr_hdr *attr;
1568 const u8 *fdata = NULL; /* points to found item */
1572 /* find n-th valid Tunnel-Password attribute */
1573 for (i = 0; i < msg->attr_used; i++) {
1574 attr = radius_get_attr_hdr(msg, i);
1576 attr->type != RADIUS_ATTR_TUNNEL_PASSWORD) {
1579 if (attr->length <= 5)
1581 data = (const u8 *) (attr + 1);
1582 dlen = attr->length - sizeof(*attr);
1583 if (dlen <= 3 || dlen % 16 != 3)
1596 /* alloc writable memory for decryption */
1597 buf = os_malloc(fdlen);
1600 os_memcpy(buf, fdata, fdlen);
1607 /* decrypt blocks */
1608 pos = buf + buflen - 16; /* last block */
1609 while (pos >= str + 16) { /* all but the first block */
1611 len[0] = secret_len;
1614 md5_vector(2, addr, len, hash);
1616 for (i = 0; i < 16; i++)
1622 /* decrypt first block */
1626 len[0] = secret_len;
1627 addr[1] = sent_msg->hdr->authenticator;
1631 md5_vector(3, addr, len, hash);
1633 for (i = 0; i < 16; i++)
1636 /* derive plaintext length from first subfield */
1637 *keylen = (unsigned char) str[0];
1638 if ((u8 *) (str + *keylen) >= (u8 *) (buf + buflen)) {
1639 /* decryption error - invalid key length */
1643 /* empty password */
1647 /* copy passphrase into new buffer */
1648 ret = os_malloc(*keylen);
1650 os_memcpy(ret, str + 1, *keylen);
1653 /* return new buffer */
1659 void radius_free_class(struct radius_class_data *c)
1664 for (i = 0; i < c->count; i++)
1665 os_free(c->attr[i].data);
1672 int radius_copy_class(struct radius_class_data *dst,
1673 const struct radius_class_data *src)
1677 if (src->attr == NULL)
1680 dst->attr = os_calloc(src->count, sizeof(struct radius_attr_data));
1681 if (dst->attr == NULL)
1686 for (i = 0; i < src->count; i++) {
1687 dst->attr[i].data = os_malloc(src->attr[i].len);
1688 if (dst->attr[i].data == NULL)
1691 os_memcpy(dst->attr[i].data, src->attr[i].data,
1693 dst->attr[i].len = src->attr[i].len;
1700 u8 radius_msg_find_unlisted_attr(struct radius_msg *msg, u8 *attrs)
1703 struct radius_attr_hdr *attr;
1705 for (i = 0; i < msg->attr_used; i++) {
1706 attr = radius_get_attr_hdr(msg, i);
1708 for (j = 0; attrs[j]; j++) {
1709 if (attr->type == attrs[j])
1714 return attr->type; /* unlisted attr */
1721 int radius_gen_session_id(u8 *id, size_t len)
1724 * Acct-Session-Id and Acct-Multi-Session-Id should be globally and
1725 * temporarily unique. A high quality random number is required
1726 * therefore. This could be be improved by switching to a GUID.
1728 return os_get_random(id, len);