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ap: Write extra frame IEs from the user 

Add an API for the ap.h users to add extra IEs to outgoing management
frames: beacons, etc.
This commit is contained in:
Andrew Zaborowski 2021-03-11 14:07:23 +01:00 committed by Denis Kenzior
parent f7b5bd4a79
commit 18a63f91fd
2 changed files with 112 additions and 20 deletions
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109
src/ap.c
View File

@ -467,11 +467,48 @@ static void ap_set_rsn_info(struct ap_state *ap, struct ie_rsn_info *rsn)
rsn->group_cipher = ap->group_cipher;
}
static size_t ap_get_extra_ies_len(struct ap_state *ap,
enum mpdu_management_subtype type,
const struct mmpdu_header *client_frame,
size_t client_frame_len)
{
size_t len = 0;
if (ap->ops->get_extra_ies_len)
len += ap->ops->get_extra_ies_len(type, client_frame,
client_frame_len,
ap->user_data);
return len;
}
static size_t ap_write_extra_ies(struct ap_state *ap,
enum mpdu_management_subtype type,
const struct mmpdu_header *client_frame,
size_t client_frame_len,
uint8_t *out_buf)
{
size_t len = 0;
if (ap->ops->write_extra_ies)
len += ap->ops->write_extra_ies(type,
client_frame, client_frame_len,
out_buf + len, ap->user_data);
return len;
}
/*
* Build a Beacon frame or a Probe Response frame's header and body until
* the TIM IE. Except for the optional TIM IE which is inserted by the
* kernel when needed, our contents for both frames are the same.
* See Beacon format in 8.3.3.2 and Probe Response format in 8.3.3.10.
*
* 802.11-2016, Section 9.4.2.1:
* "The frame body components specified for many management subtypes result
* in elements ordered by ascending values of the Element ID field and then
* the Element ID Extension field (when present), with the exception of the
* MIC Management element (9.4.2.55)."
*/
static size_t ap_build_beacon_pr_head(struct ap_state *ap,
enum mpdu_management_subtype stype,
@ -537,8 +574,10 @@ static size_t ap_build_beacon_pr_head(struct ap_state *ap,
}
/* Beacon / Probe Response frame portion after the TIM IE */
static size_t ap_build_beacon_pr_tail(struct ap_state *ap, bool pr,
uint8_t *out_buf)
static size_t ap_build_beacon_pr_tail(struct ap_state *ap,
enum mpdu_management_subtype stype,
const struct mmpdu_header *req,
size_t req_len, uint8_t *out_buf)
{
size_t len;
struct ie_rsn_info rsn;
@ -556,7 +595,7 @@ static size_t ap_build_beacon_pr_tail(struct ap_state *ap, bool pr,
len = 2 + out_buf[1];
/* WSC IE */
if (pr) {
if (stype == MPDU_MANAGEMENT_SUBTYPE_PROBE_RESPONSE) {
struct wsc_probe_response wsc_pr = {};
wsc_pr.version2 = true;
@ -634,6 +673,7 @@ static size_t ap_build_beacon_pr_tail(struct ap_state *ap, bool pr,
len += wsc_ie_size;
l_free(wsc_ie);
len += ap_write_extra_ies(ap, stype, req, req_len, out_buf + len);
return len;
}
@ -648,7 +688,11 @@ static void ap_set_beacon_cb(struct l_genl_msg *msg, void *user_data)
void ap_update_beacon(struct ap_state *ap)
{
struct l_genl_msg *cmd;
uint8_t head[256], tail[256];
uint8_t head[256];
L_AUTO_FREE_VAR(uint8_t *, tail) =
l_malloc(256 + ap_get_extra_ies_len(ap,
MPDU_MANAGEMENT_SUBTYPE_BEACON,
NULL, 0));
size_t head_len, tail_len;
uint64_t wdev_id = netdev_get_wdev_id(ap->netdev);
static const uint8_t bcast_addr[6] = {
@ -660,7 +704,8 @@ void ap_update_beacon(struct ap_state *ap)
head_len = ap_build_beacon_pr_head(ap, MPDU_MANAGEMENT_SUBTYPE_BEACON,
bcast_addr, head, sizeof(head));
tail_len = ap_build_beacon_pr_tail(ap, false, tail);
tail_len = ap_build_beacon_pr_tail(ap, MPDU_MANAGEMENT_SUBTYPE_BEACON,
NULL, 0, tail);
if (L_WARN_ON(!head_len || !tail_len))
return;
@ -1198,10 +1243,15 @@ static void ap_fail_assoc_resp_cb(int err, void *user_data)
static uint32_t ap_assoc_resp(struct ap_state *ap, struct sta_state *sta,
const uint8_t *dest,
enum mmpdu_reason_code status_code,
bool reassoc, frame_xchg_cb_t callback)
bool reassoc, const struct mmpdu_header *req,
size_t req_len, frame_xchg_cb_t callback)
{
const uint8_t *addr = netdev_get_address(ap->netdev);
uint8_t mpdu_buf[128];
enum mpdu_management_subtype stype = reassoc ?
MPDU_MANAGEMENT_SUBTYPE_REASSOCIATION_RESPONSE :
MPDU_MANAGEMENT_SUBTYPE_ASSOCIATION_RESPONSE;
L_AUTO_FREE_VAR(uint8_t *, mpdu_buf) =
l_malloc(128 + ap_get_extra_ies_len(ap, stype, req, req_len));
struct mmpdu_header *mpdu = (void *) mpdu_buf;
struct mmpdu_association_response *resp;
size_t ies_len = 0;
@ -1213,9 +1263,7 @@ static uint32_t ap_assoc_resp(struct ap_state *ap, struct sta_state *sta,
/* Header */
mpdu->fc.protocol_version = 0;
mpdu->fc.type = MPDU_TYPE_MANAGEMENT;
mpdu->fc.subtype = reassoc ?
MPDU_MANAGEMENT_SUBTYPE_REASSOCIATION_RESPONSE :
MPDU_MANAGEMENT_SUBTYPE_ASSOCIATION_RESPONSE;
mpdu->fc.subtype = stype;
memcpy(mpdu->address_1, dest, 6); /* DA */
memcpy(mpdu->address_2, addr, 6); /* SA */
memcpy(mpdu->address_3, addr, 6); /* BSSID */
@ -1277,6 +1325,9 @@ static uint32_t ap_assoc_resp(struct ap_state *ap, struct sta_state *sta,
l_free(wsc_ie);
}
ies_len += ap_write_extra_ies(ap, stype, req, req_len,
resp->ies + ies_len);
send_frame:
return ap_send_mgmt_frame(ap, mpdu, resp->ies + ies_len - mpdu_buf,
callback, sta);
@ -1352,8 +1403,9 @@ static int ap_parse_supported_rates(struct ie_tlv_iter *iter,
*/
static void ap_assoc_reassoc(struct sta_state *sta, bool reassoc,
const struct mmpdu_field_capability *capability,
uint16_t listen_interval, const uint8_t *ies,
size_t ies_len)
uint16_t listen_interval,
const uint8_t *ies, size_t ies_len,
const struct mmpdu_header *req)
{
struct ap_state *ap = sta->ap;
const char *ssid = NULL;
@ -1542,6 +1594,8 @@ static void ap_assoc_reassoc(struct sta_state *sta, bool reassoc,
}
sta->assoc_resp_cmd_id = ap_assoc_resp(ap, sta, sta->addr, 0, reassoc,
req, (void *) ies + ies_len -
(void *) req,
ap_success_assoc_resp_cb);
if (!sta->assoc_resp_cmd_id)
l_error("Sending success (Re)Association Response failed");
@ -1573,6 +1627,7 @@ bad_frame:
l_free(wsc_data);
if (!ap_assoc_resp(ap, sta, sta->addr, err, reassoc,
req, (void *) ies + ies_len - (void *) req,
ap_fail_assoc_resp_cb))
l_error("Sending error (Re)Association Response failed");
}
@ -1597,7 +1652,8 @@ static void ap_assoc_req_cb(const struct mmpdu_header *hdr, const void *body,
if (!sta) {
if (!ap_assoc_resp(ap, NULL, from,
MMPDU_REASON_CODE_STA_REQ_ASSOC_WITHOUT_AUTH,
false, ap_fail_assoc_resp_cb))
false, hdr, body + body_len - (void *) hdr,
ap_fail_assoc_resp_cb))
l_error("Sending error Association Response failed");
return;
@ -1605,7 +1661,7 @@ static void ap_assoc_req_cb(const struct mmpdu_header *hdr, const void *body,
ap_assoc_reassoc(sta, false, &req->capability,
L_LE16_TO_CPU(req->listen_interval),
req->ies, body_len - sizeof(*req));
req->ies, body_len - sizeof(*req), hdr);
}
/* 802.11-2016 9.3.3.8 */
@ -1639,11 +1695,13 @@ static void ap_reassoc_req_cb(const struct mmpdu_header *hdr, const void *body,
ap_assoc_reassoc(sta, true, &req->capability,
L_LE16_TO_CPU(req->listen_interval),
req->ies, body_len - sizeof(*req));
req->ies, body_len - sizeof(*req), hdr);
return;
bad_frame:
if (!ap_assoc_resp(ap, NULL, from, err, true, ap_fail_assoc_resp_cb))
if (!ap_assoc_resp(ap, NULL, from, err, true,
hdr, body + body_len - (void *) hdr,
ap_fail_assoc_resp_cb))
l_error("Sending error Reassociation Response failed");
}
@ -1786,7 +1844,10 @@ static void ap_probe_req_cb(const struct mmpdu_header *hdr, const void *body,
struct ie_tlv_iter iter;
const uint8_t *bssid = netdev_get_address(ap->netdev);
bool match = false;
uint8_t resp[512];
L_AUTO_FREE_VAR(uint8_t *, resp) =
l_malloc(512 + ap_get_extra_ies_len(ap,
MPDU_MANAGEMENT_SUBTYPE_PROBE_RESPONSE, hdr,
body + body_len - (void *) hdr));
uint8_t *wsc_data;
ssize_t wsc_data_len;
@ -1876,7 +1937,10 @@ static void ap_probe_req_cb(const struct mmpdu_header *hdr, const void *body,
len = ap_build_beacon_pr_head(ap,
MPDU_MANAGEMENT_SUBTYPE_PROBE_RESPONSE,
hdr->address_2, resp, sizeof(resp));
len += ap_build_beacon_pr_tail(ap, true, resp + len);
len += ap_build_beacon_pr_tail(ap,
MPDU_MANAGEMENT_SUBTYPE_PROBE_RESPONSE,
hdr, body + body_len - (void *) hdr,
resp + len);
ap_send_mgmt_frame(ap, (struct mmpdu_header *) resp, len,
ap_probe_resp_cb, NULL);
@ -2109,7 +2173,11 @@ static struct l_genl_msg *ap_build_cmd_start_ap(struct ap_state *ap)
{
struct l_genl_msg *cmd;
uint8_t head[256], tail[256];
uint8_t head[256];
L_AUTO_FREE_VAR(uint8_t *, tail) =
l_malloc(256 + ap_get_extra_ies_len(ap,
MPDU_MANAGEMENT_SUBTYPE_BEACON,
NULL, 0));
size_t head_len, tail_len;
uint32_t dtim_period = 3;
@ -2139,7 +2207,8 @@ static struct l_genl_msg *ap_build_cmd_start_ap(struct ap_state *ap)
head_len = ap_build_beacon_pr_head(ap, MPDU_MANAGEMENT_SUBTYPE_BEACON,
bcast_addr, head, sizeof(head));
tail_len = ap_build_beacon_pr_tail(ap, false, tail);
tail_len = ap_build_beacon_pr_tail(ap, MPDU_MANAGEMENT_SUBTYPE_BEACON,
NULL, 0, tail);
if (!head_len || !tail_len)
return NULL;

23
src/ap.h
View File

@ -22,6 +22,7 @@
struct ap_state;
struct iovec;
enum mpdu_management_subtype;
enum ap_event_type {
AP_EVENT_START_FAILED,
@ -75,6 +76,28 @@ struct ap_config {
struct ap_ops {
void (*handle_event)(enum ap_event_type type, const void *event_data,
void *user_data);
/*
* If .write_extra_ies is provided, this callback must return an upper
* bound on the buffer space needed for the extra IEs to be sent in
* the frame of given type and, if it's not a beacon frame, in
* response to a given client frame.
*/
size_t (*get_extra_ies_len)(enum mpdu_management_subtype type,
const struct mmpdu_header *client_frame,
size_t client_frame_len,
void *user_data);
/*
* If not null, writes extra IEs to be added to the outgoing frame of
* given type and, if it's not a beacon frame, in reponse to a given
* client frame. May also react to the extra IEs in that frame.
* Returns the number of bytes written which must be less than or
* equal to the number returned by .get_extra_ies_len when called
* with the same parameters.
*/
size_t (*write_extra_ies)(enum mpdu_management_subtype type,
const struct mmpdu_header *client_frame,
size_t client_frame_len,
uint8_t *out_buf, void *user_data);
};
void ap_config_free(struct ap_config *config);