【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;} elsep2p->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;elsep2p->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_SEARCHp2p_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_scanres = 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 -1if (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);
}