hostap/src/common/gas_server.c

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/*
* Generic advertisement service (GAS) server
* Copyright (c) 2017, Qualcomm Atheros, Inc.
* Copyright (c) 2020, The Linux Foundation
*
* This software may be distributed under the terms of the BSD license.
* See README for more details.
*/
#include "includes.h"
#include "utils/common.h"
#include "utils/list.h"
#include "utils/eloop.h"
#include "ieee802_11_defs.h"
#include "gas.h"
#include "gas_server.h"
#define MAX_ADV_PROTO_ID_LEN 10
#define GAS_QUERY_TIMEOUT 10
struct gas_server_handler {
struct dl_list list;
u8 adv_proto_id[MAX_ADV_PROTO_ID_LEN];
u8 adv_proto_id_len;
struct wpabuf * (*req_cb)(void *ctx, void *resp_ctx, const u8 *sa,
const u8 *query, size_t query_len,
u16 *comeback_delay);
void (*status_cb)(void *ctx, struct wpabuf *resp, int ok);
void *ctx;
struct gas_server *gas;
};
struct gas_server_response {
struct dl_list list;
size_t offset;
u8 frag_id;
struct wpabuf *resp;
int freq;
u8 dst[ETH_ALEN];
u8 dialog_token;
struct gas_server_handler *handler;
u16 comeback_delay;
};
struct gas_server {
struct dl_list handlers; /* struct gas_server_handler::list */
struct dl_list responses; /* struct gas_server_response::list */
void (*tx)(void *ctx, int freq, const u8 *da, struct wpabuf *resp,
unsigned int wait_time);
void *ctx;
};
static void gas_server_free_response(struct gas_server_response *response);
static void gas_server_response_timeout(void *eloop_ctx, void *user_ctx)
{
struct gas_server_response *response = eloop_ctx;
wpa_printf(MSG_DEBUG, "GAS: Response @%p timeout for " MACSTR
" (dialog_token=%u freq=%d frag_id=%u sent=%lu/%lu) - drop pending data",
response, MAC2STR(response->dst), response->dialog_token,
response->freq, response->frag_id,
(unsigned long) response->offset,
(unsigned long) (response->resp ?
wpabuf_len(response->resp) : 0));
response->handler->status_cb(response->handler->ctx,
response->resp, 0);
response->resp = NULL;
dl_list_del(&response->list);
gas_server_free_response(response);
}
static void gas_server_free_response(struct gas_server_response *response)
{
if (!response)
return;
wpa_printf(MSG_DEBUG, "DPP: Free GAS response @%p", response);
eloop_cancel_timeout(gas_server_response_timeout, response, NULL);
wpabuf_free(response->resp);
os_free(response);
}
static void
gas_server_send_resp(struct gas_server *gas, struct gas_server_handler *handler,
struct gas_server_response *response,
const u8 *da, int freq, u8 dialog_token,
struct wpabuf *query_resp, u16 comeback_delay)
{
size_t max_len = (freq > 56160) ? 928 : 1400;
size_t hdr_len = 24 + 2 + 5 + 3 + handler->adv_proto_id_len + 2;
size_t resp_frag_len;
struct wpabuf *resp;
if (comeback_delay == 0 && !query_resp)
return;
response->freq = freq;
response->handler = handler;
os_memcpy(response->dst, da, ETH_ALEN);
response->dialog_token = dialog_token;
if (comeback_delay) {
/* Need more time to prepare the response */
resp_frag_len = 0;
response->comeback_delay = comeback_delay;
} else if (hdr_len + wpabuf_len(query_resp) > max_len) {
/* Need to use comeback to initiate fragmentation */
comeback_delay = 1;
resp_frag_len = 0;
} else {
/* Full response fits into the initial response */
comeback_delay = 0;
resp_frag_len = wpabuf_len(query_resp);
}
resp = gas_build_initial_resp(dialog_token, WLAN_STATUS_SUCCESS,
comeback_delay,
handler->adv_proto_id_len +
resp_frag_len);
if (!resp) {
wpabuf_free(query_resp);
gas_server_free_response(response);
return;
}
/* Advertisement Protocol element */
wpabuf_put_u8(resp, WLAN_EID_ADV_PROTO);
wpabuf_put_u8(resp, 1 + handler->adv_proto_id_len); /* Length */
wpabuf_put_u8(resp, 0x7f);
/* Advertisement Protocol ID */
wpabuf_put_data(resp, handler->adv_proto_id, handler->adv_proto_id_len);
/* Query Response Length */
wpabuf_put_le16(resp, resp_frag_len);
if (!comeback_delay && query_resp)
wpabuf_put_buf(resp, query_resp);
if (comeback_delay && !query_resp) {
wpa_printf(MSG_DEBUG, "GAS: No response available yet");
} else if (comeback_delay) {
wpa_printf(MSG_DEBUG,
"GAS: Need to fragment query response");
} else {
wpa_printf(MSG_DEBUG,
"GAS: Full query response fits in the GAS Initial Response frame");
}
response->offset = resp_frag_len;
response->resp = query_resp;
dl_list_add(&gas->responses, &response->list);
gas->tx(gas->ctx, freq, da, resp, comeback_delay ? 2000 : 0);
wpabuf_free(resp);
eloop_register_timeout(GAS_QUERY_TIMEOUT, 0,
gas_server_response_timeout, response, NULL);
}
static int
gas_server_rx_initial_req(struct gas_server *gas, const u8 *da, const u8 *sa,
const u8 *bssid, int freq, u8 dialog_token,
const u8 *data, size_t len)
{
const u8 *pos, *end, *adv_proto, *query_req;
u8 adv_proto_len;
u16 query_req_len;
struct gas_server_handler *handler;
struct wpabuf *resp;
struct gas_server_response *response;
wpa_hexdump(MSG_MSGDUMP, "GAS: Received GAS Initial Request frame",
data, len);
pos = data;
end = data + len;
if (end - pos < 2 || pos[0] != WLAN_EID_ADV_PROTO) {
wpa_printf(MSG_DEBUG,
"GAS: No Advertisement Protocol element found");
return -1;
}
pos++;
adv_proto_len = *pos++;
if (end - pos < adv_proto_len || adv_proto_len < 2) {
wpa_printf(MSG_DEBUG,
"GAS: Truncated Advertisement Protocol element");
return -1;
}
adv_proto = pos;
pos += adv_proto_len;
wpa_hexdump(MSG_MSGDUMP, "GAS: Advertisement Protocol element",
adv_proto, adv_proto_len);
if (end - pos < 2) {
wpa_printf(MSG_DEBUG, "GAS: No Query Request Length field");
return -1;
}
query_req_len = WPA_GET_LE16(pos);
pos += 2;
if (end - pos < query_req_len) {
wpa_printf(MSG_DEBUG, "GAS: Truncated Query Request field");
return -1;
}
query_req = pos;
pos += query_req_len;
wpa_hexdump(MSG_MSGDUMP, "GAS: Query Request",
query_req, query_req_len);
if (pos < end) {
wpa_hexdump(MSG_MSGDUMP,
"GAS: Ignored extra data after Query Request field",
pos, end - pos);
}
response = os_zalloc(sizeof(*response));
if (!response)
return -1;
wpa_printf(MSG_DEBUG, "DPP: Allocated GAS response @%p", response);
dl_list_for_each(handler, &gas->handlers, struct gas_server_handler,
list) {
u16 comeback_delay = 0;
if (adv_proto_len < 1 + handler->adv_proto_id_len ||
os_memcmp(adv_proto + 1, handler->adv_proto_id,
handler->adv_proto_id_len) != 0)
continue;
wpa_printf(MSG_DEBUG,
"GAS: Calling handler for the requested Advertisement Protocol ID");
resp = handler->req_cb(handler->ctx, response, sa, query_req,
query_req_len, &comeback_delay);
wpa_hexdump_buf(MSG_MSGDUMP, "GAS: Response from the handler",
resp);
if (comeback_delay)
wpa_printf(MSG_DEBUG,
"GAS: Handler requested comeback delay: %u TU",
comeback_delay);
gas_server_send_resp(gas, handler, response, sa, freq,
dialog_token, resp, comeback_delay);
return 0;
}
wpa_printf(MSG_DEBUG,
"GAS: No registered handler for the requested Advertisement Protocol ID");
gas_server_free_response(response);
return -1;
}
static void
gas_server_handle_rx_comeback_req(struct gas_server_response *response)
{
struct gas_server_handler *handler = response->handler;
struct gas_server *gas = handler->gas;
size_t max_len = (response->freq > 56160) ? 928 : 1400;
size_t hdr_len = 24 + 2 + 6 + 3 + handler->adv_proto_id_len + 2;
size_t remaining, resp_frag_len;
struct wpabuf *resp;
unsigned int wait_time = 0;
if (!response->resp) {
resp = gas_build_comeback_resp(response->dialog_token,
WLAN_STATUS_SUCCESS, 0, 0,
response->comeback_delay,
handler->adv_proto_id_len);
if (!resp) {
dl_list_del(&response->list);
gas_server_free_response(response);
return;
}
/* Advertisement Protocol element */
wpabuf_put_u8(resp, WLAN_EID_ADV_PROTO);
wpabuf_put_u8(resp, 1 + handler->adv_proto_id_len); /* Length */
wpabuf_put_u8(resp, 0x7f);
/* Advertisement Protocol ID */
wpabuf_put_data(resp, handler->adv_proto_id,
handler->adv_proto_id_len);
/* Query Response Length */
wpabuf_put_le16(resp, 0);
goto send_resp;
}
remaining = wpabuf_len(response->resp) - response->offset;
if (hdr_len + remaining > max_len)
resp_frag_len = max_len - hdr_len;
else
resp_frag_len = remaining;
wpa_printf(MSG_DEBUG,
"GAS: Sending out %u/%u remaining Query Response octets",
(unsigned int) resp_frag_len, (unsigned int) remaining);
resp = gas_build_comeback_resp(response->dialog_token,
WLAN_STATUS_SUCCESS,
response->frag_id++,
resp_frag_len < remaining, 0,
handler->adv_proto_id_len +
resp_frag_len);
if (!resp) {
dl_list_del(&response->list);
gas_server_free_response(response);
return;
}
/* Advertisement Protocol element */
wpabuf_put_u8(resp, WLAN_EID_ADV_PROTO);
wpabuf_put_u8(resp, 1 + handler->adv_proto_id_len); /* Length */
wpabuf_put_u8(resp, 0x7f);
/* Advertisement Protocol ID */
wpabuf_put_data(resp, handler->adv_proto_id, handler->adv_proto_id_len);
/* Query Response Length */
wpabuf_put_le16(resp, resp_frag_len);
wpabuf_put_data(resp, wpabuf_head_u8(response->resp) + response->offset,
resp_frag_len);
response->offset += resp_frag_len;
if (remaining > resp_frag_len)
wait_time = 2000;
send_resp:
gas->tx(gas->ctx, response->freq, response->dst, resp, wait_time);
wpabuf_free(resp);
}
static int
gas_server_rx_comeback_req(struct gas_server *gas, const u8 *da, const u8 *sa,
const u8 *bssid, int freq, u8 dialog_token)
{
struct gas_server_response *response;
dl_list_for_each(response, &gas->responses, struct gas_server_response,
list) {
if (response->dialog_token != dialog_token ||
os_memcmp(sa, response->dst, ETH_ALEN) != 0)
continue;
gas_server_handle_rx_comeback_req(response);
return 0;
}
wpa_printf(MSG_DEBUG, "GAS: No pending GAS response for " MACSTR
" (dialog token %u)", MAC2STR(sa), dialog_token);
return -1;
}
/**
* gas_query_rx - Indicate reception of a Public Action or Protected Dual frame
* @gas: GAS query data from gas_server_init()
* @da: Destination MAC address of the Action frame
* @sa: Source MAC address of the Action frame
* @bssid: BSSID of the Action frame
* @categ: Category of the Action frame
* @data: Payload of the Action frame
* @len: Length of @data
* @freq: Frequency (in MHz) on which the frame was received
* Returns: 0 if the Public Action frame was a GAS request frame or -1 if not
*/
int gas_server_rx(struct gas_server *gas, const u8 *da, const u8 *sa,
const u8 *bssid, u8 categ, const u8 *data, size_t len,
int freq)
{
u8 action, dialog_token;
const u8 *pos, *end;
if (!gas || len < 2)
return -1;
if (categ == WLAN_ACTION_PROTECTED_DUAL)
return -1; /* Not supported for now */
pos = data;
end = data + len;
action = *pos++;
dialog_token = *pos++;
if (action != WLAN_PA_GAS_INITIAL_REQ &&
action != WLAN_PA_GAS_COMEBACK_REQ)
return -1; /* Not a GAS request */
wpa_printf(MSG_DEBUG, "GAS: Received GAS %s Request frame DA=" MACSTR
" SA=" MACSTR " BSSID=" MACSTR
" freq=%d dialog_token=%u len=%u",
action == WLAN_PA_GAS_INITIAL_REQ ? "Initial" : "Comeback",
MAC2STR(da), MAC2STR(sa), MAC2STR(bssid), freq, dialog_token,
(unsigned int) len);
if (action == WLAN_PA_GAS_INITIAL_REQ)
return gas_server_rx_initial_req(gas, da, sa, bssid,
freq, dialog_token,
pos, end - pos);
return gas_server_rx_comeback_req(gas, da, sa, bssid,
freq, dialog_token);
}
static void gas_server_handle_tx_status(struct gas_server_response *response,
int ack)
{
if (ack && response->resp &&
response->offset < wpabuf_len(response->resp)) {
wpa_printf(MSG_DEBUG,
"GAS: More fragments remaining - keep pending entry");
return;
}
if (ack && !response->resp && response->comeback_delay) {
wpa_printf(MSG_DEBUG,
"GAS: Waiting for response - keep pending entry");
return;
}
if (!ack)
wpa_printf(MSG_DEBUG,
"GAS: No ACK received - drop pending entry");
else
wpa_printf(MSG_DEBUG,
"GAS: Last fragment of the response sent out - drop pending entry");
response->handler->status_cb(response->handler->ctx,
response->resp, ack);
response->resp = NULL;
dl_list_del(&response->list);
gas_server_free_response(response);
}
void gas_server_tx_status(struct gas_server *gas, const u8 *dst, const u8 *data,
size_t data_len, int ack)
{
const u8 *pos;
u8 action, code, dialog_token;
struct gas_server_response *response;
if (data_len < 24 + 3)
return;
pos = data + 24;
action = *pos++;
code = *pos++;
dialog_token = *pos++;
if (action != WLAN_ACTION_PUBLIC ||
(code != WLAN_PA_GAS_INITIAL_RESP &&
code != WLAN_PA_GAS_COMEBACK_RESP))
return;
wpa_printf(MSG_DEBUG, "GAS: TX status dst=" MACSTR
" ack=%d %s dialog_token=%u",
MAC2STR(dst), ack,
code == WLAN_PA_GAS_INITIAL_RESP ? "initial" : "comeback",
dialog_token);
dl_list_for_each(response, &gas->responses, struct gas_server_response,
list) {
if (response->dialog_token != dialog_token ||
os_memcmp(dst, response->dst, ETH_ALEN) != 0)
continue;
gas_server_handle_tx_status(response, ack);
return;
}
wpa_printf(MSG_DEBUG, "GAS: No pending response matches TX status");
}
int gas_server_set_resp(struct gas_server *gas, void *resp_ctx,
struct wpabuf *resp)
{
struct gas_server_response *tmp, *response = NULL;
dl_list_for_each(tmp, &gas->responses, struct gas_server_response,
list) {
if (tmp == resp_ctx) {
response = tmp;
break;
}
}
if (!response || response->resp)
return -1;
response->resp = resp;
return 0;
}
struct gas_server * gas_server_init(void *ctx,
void (*tx)(void *ctx, int freq,
const u8 *da,
struct wpabuf *buf,
unsigned int wait_time))
{
struct gas_server *gas;
gas = os_zalloc(sizeof(*gas));
if (!gas)
return NULL;
gas->ctx = ctx;
gas->tx = tx;
dl_list_init(&gas->handlers);
dl_list_init(&gas->responses);
return gas;
}
void gas_server_deinit(struct gas_server *gas)
{
struct gas_server_handler *handler, *tmp;
struct gas_server_response *response, *tmp_r;
if (!gas)
return;
dl_list_for_each_safe(handler, tmp, &gas->handlers,
struct gas_server_handler, list) {
dl_list_del(&handler->list);
os_free(handler);
}
dl_list_for_each_safe(response, tmp_r, &gas->responses,
struct gas_server_response, list) {
dl_list_del(&response->list);
gas_server_free_response(response);
}
os_free(gas);
}
int gas_server_register(struct gas_server *gas,
const u8 *adv_proto_id, u8 adv_proto_id_len,
struct wpabuf *
(*req_cb)(void *ctx, void *resp_ctx, const u8 *sa,
const u8 *query, size_t query_len,
u16 *comeback_delay),
void (*status_cb)(void *ctx, struct wpabuf *resp,
int ok),
void *ctx)
{
struct gas_server_handler *handler;
if (!gas || adv_proto_id_len > MAX_ADV_PROTO_ID_LEN)
return -1;
handler = os_zalloc(sizeof(*handler));
if (!handler)
return -1;
os_memcpy(handler->adv_proto_id, adv_proto_id, adv_proto_id_len);
handler->adv_proto_id_len = adv_proto_id_len;
handler->req_cb = req_cb;
handler->status_cb = status_cb;
handler->ctx = ctx;
handler->gas = gas;
dl_list_add(&gas->handlers, &handler->list);
return 0;
}