P2P: Add retry mechanism for GO Negotiation Confirmation

wpa_supplicant now retries for P2P_GO_NEG_CNF_MAX_RETRY_COUNT times if
it doesn't receive acknowledgement for GO Negotiation Confirmation
frame. Currently, P2P_GO_NEG_CNF_MAX_RETRY_COUNT is set to 1.

While this is not strictly speaking following the P2P specification,
this can improve robustness of GO Negotiation in environments with
interference and also with peer devices that do not behave properly
(e.g., by not remaining awake on the negotiation channel through the
full GO Negotiation).

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>

diff --git a/src/p2p/p2p.c b/src/p2p/p2p.c
index ea16761..bcc7e64 100644 (file)
--- a/src/p2p/p2p.c
+++ b/src/p2p/p2p.c
@@ -218,6 +218,8 @@ void p2p_go_neg_failed(struct p2p_data *p2p, struct p2p_device *peer,
        os_memset(&res, 0, sizeof(res));
        res.status = status;
        if (peer) {
+               wpabuf_free(peer->go_neg_conf);
+               peer->go_neg_conf = NULL;
                os_memcpy(res.peer_device_addr, peer->info.p2p_device_addr,
                          ETH_ALEN);
                os_memcpy(res.peer_interface_addr, peer->intended_addr,
@@ -802,6 +804,7 @@ static void p2p_device_free(struct p2p_data *p2p, struct p2p_device *dev)
        }
 
        wpabuf_free(dev->info.wfd_subelems);
+       wpabuf_free(dev->go_neg_conf);
 
        os_free(dev);
 }
@@ -1611,6 +1614,8 @@ void p2p_go_complete(struct p2p_data *p2p, struct p2p_device *peer)
        peer->go_neg_req_sent = 0;
        peer->wps_method = WPS_NOT_READY;
        peer->oob_pw_id = 0;
+       wpabuf_free(peer->go_neg_conf);
+       peer->go_neg_conf = NULL;
 
        p2p_set_state(p2p, P2P_PROVISIONING);
        p2p->cfg->go_neg_completed(p2p->cfg->cb_ctx, &res);
@@ -2952,13 +2957,44 @@ static void p2p_go_neg_conf_cb(struct p2p_data *p2p,
        struct p2p_device *dev;
 
        p2p_dbg(p2p, "GO Negotiation Confirm TX callback: result=%d", result);
-       p2p->cfg->send_action_done(p2p->cfg->cb_ctx);
        if (result == P2P_SEND_ACTION_FAILED) {
+               p2p->cfg->send_action_done(p2p->cfg->cb_ctx);
                p2p_go_neg_failed(p2p, p2p->go_neg_peer, -1);
                return;
        }
+
+       dev = p2p->go_neg_peer;
+
        if (result == P2P_SEND_ACTION_NO_ACK) {
                /*
+                * Retry GO Negotiation Confirmation
+                * P2P_GO_NEG_CNF_MAX_RETRY_COUNT times if we did not receive
+                * ACK for confirmation.
+                */
+               if (dev && dev->go_neg_conf &&
+                   dev->go_neg_conf_sent <= P2P_GO_NEG_CNF_MAX_RETRY_COUNT) {
+                       p2p_dbg(p2p, "GO Negotiation Confirm retry %d",
+                               dev->go_neg_conf_sent);
+                       p2p->pending_action_state = P2P_PENDING_GO_NEG_CONFIRM;
+                       if (p2p_send_action(p2p, dev->go_neg_conf_freq,
+                                           dev->info.p2p_device_addr,
+                                           p2p->cfg->dev_addr,
+                                           dev->info.p2p_device_addr,
+                                           wpabuf_head(dev->go_neg_conf),
+                                           wpabuf_len(dev->go_neg_conf), 0) >=
+                           0) {
+                               dev->go_neg_conf_sent++;
+                               return;
+                       }
+                       p2p_dbg(p2p, "Failed to re-send Action frame");
+
+                       /*
+                        * Continue with the assumption that the first attempt
+                        * went through and just the ACK frame was lost.
+                        */
+               }
+
+               /*
                 * It looks like the TX status for GO Negotiation Confirm is
                 * often showing failure even when the peer has actually
                 * received the frame. Since the peer may change channels
@@ -2971,7 +3007,8 @@ static void p2p_go_neg_conf_cb(struct p2p_data *p2p,
                p2p_dbg(p2p, "Assume GO Negotiation Confirm TX was actually received by the peer even though Ack was not reported");
        }
 
-       dev = p2p->go_neg_peer;
+       p2p->cfg->send_action_done(p2p->cfg->cb_ctx);
+
        if (dev == NULL)
                return;
 

diff --git a/src/p2p/p2p_go_neg.c b/src/p2p/p2p_go_neg.c
index a32cfac..ac93902 100644 (file)
--- a/src/p2p/p2p_go_neg.c
+++ b/src/p2p/p2p_go_neg.c
@@ -896,7 +896,6 @@ void p2p_process_go_neg_resp(struct p2p_data *p2p, const u8 *sa,
                             const u8 *data, size_t len, int rx_freq)
 {
        struct p2p_device *dev;
-       struct wpabuf *conf;
        int go = -1;
        struct p2p_message msg;
        u8 status = P2P_SC_SUCCESS;
@@ -1101,10 +1100,13 @@ void p2p_process_go_neg_resp(struct p2p_data *p2p, const u8 *sa,
        os_memcpy(dev->intended_addr, msg.intended_addr, ETH_ALEN);
 
 fail:
-       conf = p2p_build_go_neg_conf(p2p, dev, msg.dialog_token, status,
-                                    msg.operating_channel, go);
+       /* Store GO Negotiation Confirmation to allow retransmission */
+       wpabuf_free(dev->go_neg_conf);
+       dev->go_neg_conf = p2p_build_go_neg_conf(p2p, dev, msg.dialog_token,
+                                                status, msg.operating_channel,
+                                                go);
        p2p_parse_free(&msg);
-       if (conf == NULL)
+       if (dev->go_neg_conf == NULL)
                return;
        p2p_dbg(p2p, "Sending GO Negotiation Confirm");
        if (status == P2P_SC_SUCCESS) {
@@ -1116,13 +1118,18 @@ fail:
                freq = rx_freq;
        else
                freq = dev->listen_freq;
+
+       dev->go_neg_conf_freq = freq;
+       dev->go_neg_conf_sent = 0;
+
        if (p2p_send_action(p2p, freq, sa, p2p->cfg->dev_addr, sa,
-                           wpabuf_head(conf), wpabuf_len(conf), 200) < 0) {
+                           wpabuf_head(dev->go_neg_conf),
+                           wpabuf_len(dev->go_neg_conf), 200) < 0) {
                p2p_dbg(p2p, "Failed to send Action frame");
                p2p_go_neg_failed(p2p, dev, -1);
                p2p->cfg->send_action_done(p2p->cfg->cb_ctx);
-       }
-       wpabuf_free(conf);
+       } else
+               dev->go_neg_conf_sent++;
        if (status != P2P_SC_SUCCESS) {
                p2p_dbg(p2p, "GO Negotiation failed");
                p2p_go_neg_failed(p2p, dev, status);

diff --git a/src/p2p/p2p_i.h b/src/p2p/p2p_i.h
index 8c225ec..44b66c4 100644 (file)
--- a/src/p2p/p2p_i.h
+++ b/src/p2p/p2p_i.h
@@ -12,6 +12,8 @@
 #include "utils/list.h"
 #include "p2p.h"
 
+#define P2P_GO_NEG_CNF_MAX_RETRY_COUNT 1
+
 enum p2p_role_indication;
 
 enum p2p_go_state {
@@ -108,6 +110,22 @@ struct p2p_device {
 
        u8 go_timeout;
        u8 client_timeout;
+
+       /**
+        * go_neg_conf_sent - Number of GO Negotiation Confirmation retries
+        */
+       u8 go_neg_conf_sent;
+
+       /**
+        * freq - Frquency on which the GO Negotiation Confirmation is sent
+        */
+       int go_neg_conf_freq;
+
+       /**
+        * go_neg_conf - GO Negotiation Confirmation frame
+        */
+       struct wpabuf *go_neg_conf;
+
        int sd_pending_bcast_queries;
 };