P2P: Avoid unsafe pre-configured channel as channel preference

Do not select pre-configured channel as operating channel preference if
it is unavailable maybe due to interference or possible known
co-existence constraints, and try to select random available channel.

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

diff --git a/src/p2p/p2p.c b/src/p2p/p2p.c
index c5bf41fe820fa0df5c1b27d85472e2dbd0d0ee9c..b2186e787430e09dc744e3fdffe6047ea7546452 100644 (file)
--- a/src/p2p/p2p.c
+++ b/src/p2p/p2p.c
@@ -1208,10 +1208,51 @@ static void p2p_prepare_channel_best(struct p2p_data *p2p)
                   0) {
                p2p_dbg(p2p, "Select possible 5 GHz channel (op_class %u channel %u) as operating channel preference",
                        p2p->op_reg_class, p2p->op_channel);
-       } else {
+       } else if (p2p_channels_includes(&p2p->cfg->channels,
+                                        p2p->cfg->op_reg_class,
+                                        p2p->cfg->op_channel)) {
                p2p_dbg(p2p, "Select pre-configured channel as operating channel preference");
                p2p->op_reg_class = p2p->cfg->op_reg_class;
                p2p->op_channel = p2p->cfg->op_channel;
+       } else {
+               u8 op_chans[3];
+               u8 *op_chan;
+               size_t num_channels = 0;
+               unsigned int r;
+
+               /* Try to find available social channels from 2.4 GHz */
+               if (p2p_channels_includes(&p2p->cfg->channels, 81, 1))
+                       op_chans[num_channels++] = 1;
+               if (p2p_channels_includes(&p2p->cfg->channels, 81, 6))
+                       op_chans[num_channels++] = 6;
+               if (p2p_channels_includes(&p2p->cfg->channels, 81, 11))
+                       op_chans[num_channels++] = 11;
+
+               if (num_channels) {
+                       p2p_dbg(p2p, "Select random available social channel from 2.4 GHz band as operating channel preference");
+                       op_chan = op_chans;
+               } else {
+                       struct p2p_reg_class *class;
+
+                       /* Select any random available channel from the first
+                        * operating class */
+                       p2p_dbg(p2p, "Select random available channel from operating class %d as operating channel preference",
+                               p2p->op_reg_class);
+                       class = &p2p->cfg->channels.reg_class[0];
+                       p2p->op_reg_class = class->reg_class;
+                       op_chan = &class->channel[0];
+                       num_channels = class->channels;
+                       if (num_channels == 0) {
+                               /* Should not happen, but make sure we do not
+                                * try to divide by zero */
+                               op_chan = op_chans;
+                               op_chans[0] = 1;
+                               num_channels = 1;
+                       }
+               }
+               os_get_random((u8 *) &r, sizeof(r));
+               r %= num_channels;
+               p2p->op_channel = op_chan[r];
        }
 
        os_memcpy(&p2p->channels, &p2p->cfg->channels,