【MTK平台】【wpa_supplicant】关于wpa_supplicant_8/src/p2p/p2p.c文件的介绍

本文主要介绍external/wpa_supplicant_8/src/p2p/p2p.c文件

先看下p2p_find 这个方法

P2P_find 主要用于 P2P（点对点）网络中查找其他对等方的功能。另外可以看到设置P2P模块的状态为 P2P_SEARCH

int p2p_find(struct p2p_data *p2p, unsigned int timeout,
	     enum p2p_discovery_type type,
	     unsigned int num_req_dev_types, const u8 *req_dev_types,
	     const u8 *dev_id, unsigned int search_delay,
	     u8 seek_count, const char **seek, int freq, bool include_6ghz)
{
	int res;
	struct os_reltime start;

	p2p_dbg(p2p, "Starting find (type=%d)", type);
    //确认P2P扫描已经可以使用
	if (p2p->p2p_scan_running) {
		p2p_dbg(p2p, "p2p_scan is already running");
	}

	p2p_free_req_dev_types(p2p);
	if (req_dev_types && num_req_dev_types) {
		p2p->req_dev_types = os_memdup(req_dev_types,
					       num_req_dev_types *
					       WPS_DEV_TYPE_LEN);
		if (p2p->req_dev_types == NULL)
			return -1;
		p2p->num_req_dev_types = num_req_dev_types;
	}

	if (dev_id) {
		os_memcpy(p2p->find_dev_id_buf, dev_id, ETH_ALEN);
		p2p->find_dev_id = p2p->find_dev_id_buf;
	} else
		p2p->find_dev_id = NULL;
	p2p->include_6ghz = p2p_wfd_enabled(p2p) && include_6ghz;
	if (seek_count == 0 || !seek) {
		/* Not an ASP search */
		p2p->p2ps_seek = 0;
	} else if (seek_count == 1 && seek && (!seek[0] || !seek[0][0])) {
		/*
		 * An empty seek string means no hash values, but still an ASP
		 * search.
		 */
		p2p_dbg(p2p, "ASP search");
		p2p->p2ps_seek_count = 0;
		p2p->p2ps_seek = 1;
	} else if (seek && seek_count <= P2P_MAX_QUERY_HASH) {
		u8 buf[P2PS_HASH_LEN];
		int i, count = 0;

		for (i = 0; i < seek_count; i++) {
			if (!p2ps_gen_hash(p2p, seek[i], buf))
				continue;

			p2p_dbg(p2p, "Seek service %s hash " MACSTR,
				seek[i], MAC2STR(buf));
			os_memcpy(&p2p->p2ps_seek_hash[count * P2PS_HASH_LEN],
				  buf, P2PS_HASH_LEN);
			count++;
		}

		p2p->p2ps_seek_count = count;
		p2p->p2ps_seek = 1;
	} else {
		p2p->p2ps_seek_count = 0;
		p2p->p2ps_seek = 1;
	}

	/* Special case to perform wildcard search */
	if (p2p->p2ps_seek_count == 0 && p2p->p2ps_seek) {
		p2p->p2ps_seek_count = 1;
		os_memcpy(&p2p->p2ps_seek_hash, p2p->wild_card_hash,
			  P2PS_HASH_LEN);
	}
    //P2P_AFTER_SCAN_NOTHING表示P2P设备完成scan动作后，无需做其他动作
	p2p->start_after_scan = P2P_AFTER_SCAN_NOTHING;
	p2p_clear_timeout(p2p);
	if (p2p->pending_listen_freq) {
		p2p_dbg(p2p, "Clear pending_listen_freq for p2p_find");
		p2p->pending_listen_freq = 0;
	}
    //停止监听
	p2p->cfg->stop_listen(p2p->cfg->cb_ctx);
	p2p->find_pending_full = 0;
	p2p->find_type = type;
	if (freq != 2412 && freq != 2437 && freq != 2462 && freq != 60480)
		p2p->find_specified_freq = freq;
	else
		p2p->find_specified_freq = 0;
	p2p_device_clear_reported(p2p);
	os_memset(p2p->sd_query_no_ack, 0, ETH_ALEN);
    //设置P2P模块的状态为 P2P_SEARCH
	p2p_set_state(p2p, P2P_SEARCH);
	p2p->search_delay = search_delay;
	p2p->in_search_delay = 0;
	eloop_cancel_timeout(p2p_find_timeout, p2p, NULL);
	p2p->last_p2p_find_timeout = timeout;
	if (timeout)
        //注册一个扫描超时处理任务
		eloop_register_timeout(timeout, 0, p2p_find_timeout,
				       p2p, NULL);
	os_get_reltime(&start);
	switch (type) {
	case P2P_FIND_START_WITH_FULL:
		if (freq > 0) {
			/*
			 * Start with the specified channel and then move to
			 * scans for social channels and this specific channel.
			 */
			res = p2p->cfg->p2p_scan(p2p->cfg->cb_ctx,
						 P2P_SCAN_SPECIFIC, freq,
						 p2p->num_req_dev_types,
						 p2p->req_dev_types, dev_id,
						 DEV_PW_DEFAULT,
						 p2p->include_6ghz);
			break;
		}
		/* fall through */
	case P2P_FIND_PROGRESSIVE: //p2p_scan指向函数 wpas_p2p_scan
		res = p2p->cfg->p2p_scan(p2p->cfg->cb_ctx, P2P_SCAN_FULL, 0,
					 p2p->num_req_dev_types,
					 p2p->req_dev_types, dev_id,
					 DEV_PW_DEFAULT, p2p->include_6ghz);
		break;
	case P2P_FIND_ONLY_SOCIAL:
		res = p2p->cfg->p2p_scan(p2p->cfg->cb_ctx, P2P_SCAN_SOCIAL, 0,
					 p2p->num_req_dev_types,
					 p2p->req_dev_types, dev_id,
					 DEV_PW_DEFAULT, p2p->include_6ghz);
		break;
	default:
		return -1;
	}

	if (!res)
		p2p->find_start = start;

	if (res != 0 && p2p->p2p_scan_running) {
		p2p_dbg(p2p, "Failed to start p2p_scan - another p2p_scan was already running");
		/* wait for the previous p2p_scan to complete */
		if (type == P2P_FIND_PROGRESSIVE ||
		    (type == P2P_FIND_START_WITH_FULL && freq == 0))
			p2p->find_pending_full = 1;
		res = 0; /* do not report failure */
	} else if (res != 0) {
		p2p_dbg(p2p, "Failed to start p2p_scan");
		p2p_set_state(p2p, P2P_IDLE);
		eloop_cancel_timeout(p2p_find_timeout, p2p, NULL);
	}

	return res;
}

 接着看下P2P模块的状态为 P2P_SEARCH后如何进行进入listen状态

 也就是p2p_listen_in_find这个方法

static void p2p_listen_in_find(struct p2p_data *p2p, int dev_disc)
{
	unsigned int r, tu;
	int freq;
	struct wpabuf *ies;

	p2p_dbg(p2p, "Starting short listen state (state=%s)",
		p2p_state_txt(p2p->state));

	if (p2p->pending_listen_freq) {
		/* We have a pending p2p_listen request */
		p2p_dbg(p2p, "p2p_listen command pending already");
		return;
	}
    //根据 p2p_supplicant.conf中listen_channel等配置参数获取对应的频段
	freq = p2p_channel_to_freq(p2p->cfg->reg_class, p2p->cfg->channel);
	if (freq < 0) {
		p2p_dbg(p2p, "Unknown regulatory class/channel");
		return;
	}
    //计算需要在listen state 等待的时间
	if (os_get_random((u8 *) &r, sizeof(r)) < 0)
		r = 0;
	tu = (r % ((p2p->max_disc_int - p2p->min_disc_int) + 1) +
	      p2p->min_disc_int) * 100;
	if (p2p->max_disc_tu >= 0 && tu > (unsigned int) p2p->max_disc_tu)
		tu = p2p->max_disc_tu;
	if (!dev_disc && tu < 100)
		tu = 100; /* Need to wait in non-device discovery use cases */
	if (p2p->cfg->max_listen && 1024 * tu / 1000 > p2p->cfg->max_listen)
		tu = p2p->cfg->max_listen * 1000 / 1024;

	if (tu == 0) {
		p2p_dbg(p2p, "Skip listen state since duration was 0 TU");
		p2p_set_timeout(p2p, 0, 0);
		return;
	}
    //构造P2P Probe Response帧，当我们在Listen state收到其他设备发来的Probe Request帧后，wifi驱动将直接回复此处设置的 P2P Probe Response帧。
	ies = p2p_build_probe_resp_ies(p2p, NULL, 0);
	if (ies == NULL)
		return;

	p2p->pending_listen_freq = freq;
	p2p->pending_listen_sec = 0;
	p2p->pending_listen_usec = 1024 * tu;
    //start_listen指向 wpas_start_listen 函数
	if (p2p->cfg->start_listen(p2p->cfg->cb_ctx, freq, 1024 * tu / 1000,
		    ies) < 0) {
		p2p_dbg(p2p, "Failed to start listen mode");
		p2p->pending_listen_freq = 0;
	}
	wpabuf_free(ies);
}

在来看p2p_connect函数，其代码如下所示

这里面有3个重要的知识点

1、是 breaker值在每次发起P2P_CONNECT时都取反一次，这样做的目的是在双方的Intent值相同的情况下，多次协商时，双方都有机会做GO。并且在发送Request时才填入自己的breaker值，在回应Response时，是把对方的breaker值取反后作为breaker值发送。

2. 如果当前P2P还在扫描过程中，则设置start_after_scan为P2P_AFTER_SCAN_CONNECT标志，当scan结束后，在扫描结果处理流程中，该标志将通知P2P进入connect处理流程

3.   p2p_connect_send发送GON Request帧

int p2p_connect(struct p2p_data *p2p, const u8 *peer_addr,
		enum p2p_wps_method wps_method,
		int go_intent, const u8 *own_interface_addr,
		unsigned int force_freq, int persistent_group,
		const u8 *force_ssid, size_t force_ssid_len,
		int pd_before_go_neg, unsigned int pref_freq, u16 oob_pw_id)
{
	struct p2p_device *dev;

	p2p_dbg(p2p, "Request to start group negotiation - peer=" MACSTR
		"  GO Intent=%d  Intended Interface Address=" MACSTR
		" wps_method=%d persistent_group=%d pd_before_go_neg=%d "
		"oob_pw_id=%u allow_6ghz=%d",
		MAC2STR(peer_addr), go_intent, MAC2STR(own_interface_addr),
		wps_method, persistent_group, pd_before_go_neg, oob_pw_id,
		p2p->allow_6ghz);
    //获取当前设备p2p dev设备的信息
	dev = p2p_get_device(p2p, peer_addr);
	if (dev == NULL || (dev->flags & P2P_DEV_PROBE_REQ_ONLY)) {
		p2p_dbg(p2p, "Cannot connect to unknown P2P Device " MACSTR,
			MAC2STR(peer_addr));
		return -1;
	}
    // 如果指定了工作频段，则需要判断是否支持该工作频段，否则return -1
	if (p2p_prepare_channel(p2p, dev, force_freq, pref_freq,
				go_intent == 15) < 0)
		return -1;

	if (dev->flags & P2P_DEV_GROUP_CLIENT_ONLY) {
		if (!(dev->info.dev_capab &
		      P2P_DEV_CAPAB_CLIENT_DISCOVERABILITY)) {
			p2p_dbg(p2p, "Cannot connect to P2P Device " MACSTR
				" that is in a group and is not discoverable",
				MAC2STR(peer_addr));
			return -1;
		}
		if (dev->oper_freq <= 0) {
			p2p_dbg(p2p, "Cannot connect to P2P Device " MACSTR
				" with incomplete information",
				MAC2STR(peer_addr));
			return -1;
		}

		/*
		 * First, try to connect directly. If the peer does not
		 * acknowledge frames, assume it is sleeping and use device
		 * discoverability via the GO at that point.
		 */
	}

	p2p->ssid_set = 0;
	if (force_ssid) {
		wpa_hexdump_ascii(MSG_DEBUG, "P2P: Forced SSID",
				  force_ssid, force_ssid_len);
		os_memcpy(p2p->ssid, force_ssid, force_ssid_len);
		p2p->ssid_len = force_ssid_len;
		p2p->ssid_set = 1;
	}

	dev->flags &= ~P2P_DEV_NOT_YET_READY;
	dev->flags &= ~P2P_DEV_USER_REJECTED;
	dev->flags &= ~P2P_DEV_WAIT_GO_NEG_RESPONSE;
	dev->flags &= ~P2P_DEV_WAIT_GO_NEG_CONFIRM;
	if (pd_before_go_neg)
		dev->flags |= P2P_DEV_PD_BEFORE_GO_NEG;
	else {
		dev->flags &= ~P2P_DEV_PD_BEFORE_GO_NEG;
		/*
		 * Assign dialog token and tie breaker here to use the same
		 * values in each retry within the same GO Negotiation exchange.
		 */
		dev->dialog_token++;
		if (dev->dialog_token == 0)
			dev->dialog_token = 1;
		dev->tie_breaker = p2p->next_tie_breaker;
		p2p->next_tie_breaker = !p2p->next_tie_breaker;//这里是对intent的值取反
	}
	dev->connect_reqs = 0;
	dev->go_neg_req_sent = 0;
	dev->go_state = UNKNOWN_GO;
	p2p_set_dev_persistent(dev, persistent_group);
	p2p->go_intent = go_intent;
	os_memcpy(p2p->intended_addr, own_interface_addr, ETH_ALEN);

	if (p2p->state != P2P_IDLE)
		p2p_stop_find(p2p);

	dev->wps_method = wps_method;
	dev->oob_pw_id = oob_pw_id;
	dev->status = P2P_SC_SUCCESS;

	if (p2p->p2p_scan_running) {
		p2p_dbg(p2p, "p2p_scan running - delay connect send");
/*
如果当前P2P还在扫描过程中，则设置start_after_scan为P2P_AFTER_SCAN_CONNECT标志，
当scan结束后，在扫描结果处理流程中，该标志将通知P2P进入connect处理流程。
*/
		p2p->start_after_scan = P2P_AFTER_SCAN_CONNECT;
		os_memcpy(p2p->after_scan_peer, peer_addr, ETH_ALEN);
		return 0;
	}
    // 下面这个函数将发送GON Request帧
  	return p2p_connect_send(p2p, dev);
}

p2p_set_state和p2p_set_timeout记录了P2P: State和Timeout

void p2p_set_state(struct p2p_data *p2p, int new_state)
{
	p2p_dbg(p2p, "State %s -> %s",
		p2p_state_txt(p2p->state), p2p_state_txt(new_state));
	p2p->state = new_state;

	if (new_state == P2P_IDLE && p2p->pending_channel) {
		p2p_dbg(p2p, "Apply change in listen channel");
		p2p->cfg->reg_class = p2p->pending_reg_class;
		p2p->cfg->channel = p2p->pending_channel;
		p2p->pending_reg_class = 0;
		p2p->pending_channel = 0;
	}
}


void p2p_set_timeout(struct p2p_data *p2p, unsigned int sec, unsigned int usec)
{
	p2p_dbg(p2p, "Set timeout (state=%s): %u.%06u sec",
		p2p_state_txt(p2p->state), sec, usec);
	eloop_cancel_timeout(p2p_state_timeout, p2p, NULL);
	eloop_register_timeout(sec, usec, p2p_state_timeout, p2p, NULL);
}