client: Use pcap_stats and export them as statistics

Attempt to write code that detects the wrap and is doing the
right thing when it happens.

Change-Id: I501ebc49d3e86b0605ec1fbe2f62aee3f362aa36

3 files changed, 66 insertions, 0 deletions

diff --git a/include/osmo-pcap/osmo_pcap_client.h b/include/osmo-pcap/osmo_pcap_client.h
index 90cd5ad..ee81e50 100644
--- a/include/osmo-pcap/osmo_pcap_client.h
+++ b/include/osmo-pcap/osmo_pcap_client.h
@@ -38,6 +38,9 @@ enum {
 	CLIENT_CTR_QERR,
 	CLIENT_CTR_PERR,
 	CLIENT_CTR_WERR,
+	CLIENT_CTR_P_RECV,
+	CLIENT_CTR_P_DROP,
+	CLIENT_CTR_P_IFDROP,
 };
 
 struct osmo_pcap_client {
@@ -45,6 +48,11 @@ struct osmo_pcap_client {
 	pcap_t *handle;
 	char errbuf[PCAP_ERRBUF_SIZE];
 
+	u_int last_ps_recv;
+	u_int last_ps_drop;
+	u_int last_ps_ifdrop;
+	struct osmo_timer_list pcap_stat_timer;
+
 	struct bpf_program bpf;
 	char   *filter_string;
 	int filter_itself;
diff --git a/src/osmo_client_core.c b/src/osmo_client_core.c
index 4455c95..abef787 100644
--- a/src/osmo_client_core.c
+++ b/src/osmo_client_core.c
@@ -171,6 +171,56 @@ static int pcap_read_cb(struct osmo_fd *fd, unsigned int what)
 	return 0;
 }
 
+static inline u_int P_CAP_UINT_MAX()
+{
+	u_int val = 0;
+	return ~val;
+}
+
+static void add_psbl_wrapped_ctr(struct osmo_pcap_client *client,
+				u_int *old_val, u_int new_val, int ctr)
+{
+	/*
+	 * Wrapped..
+	 * So let's at from N to XYZ_MAX
+	 * and then from 0 to new_val
+	 * Only issue is we don't know sizeof(u_int)
+	 */
+	if (*old_val > new_val) {
+		rate_ctr_add(&client->ctrg->ctr[ctr], P_CAP_UINT_MAX() - *old_val);
+		rate_ctr_add(&client->ctrg->ctr[ctr], new_val);
+		*old_val = new_val;
+		return;
+	}
+
+	/* Just increment it */
+	rate_ctr_add(&client->ctrg->ctr[ctr], new_val - *old_val);
+	*old_val = new_val;
+}
+
+static void pcap_check_stats_cb(void *_client)
+{
+	struct pcap_stat stat;
+	struct osmo_pcap_client *client = _client;
+	int rc;
+
+	/* reschedule */
+	osmo_timer_schedule(&client->pcap_stat_timer, 10, 0);
+
+	memset(&stat, 0, sizeof(stat));
+	rc = pcap_stats(client->handle, &stat);
+	if (rc != 0) {
+		LOGP(DCLIENT, LOGL_ERROR, "Failed to query pcap stats: %s\n",
+			pcap_geterr(client->handle));
+		rate_ctr_inc(&client->ctrg->ctr[CLIENT_CTR_PERR]);
+		return;
+	}
+
+	add_psbl_wrapped_ctr(client, &client->last_ps_recv, stat.ps_recv, CLIENT_CTR_P_RECV);
+	add_psbl_wrapped_ctr(client, &client->last_ps_drop, stat.ps_drop, CLIENT_CTR_P_DROP);
+	add_psbl_wrapped_ctr(client, &client->last_ps_ifdrop, stat.ps_ifdrop, CLIENT_CTR_P_IFDROP);
+}
+
 static int osmo_install_filter(struct osmo_pcap_client *client)
 {
 	int rc;
@@ -216,6 +266,7 @@ static void free_all(struct osmo_pcap_client *client)
 	}
 
 	pcap_close(client->handle);
+	osmo_timer_del(&client->pcap_stat_timer);
 	client->handle = NULL;
 }
 
@@ -260,6 +311,10 @@ int osmo_client_capture(struct osmo_pcap_client *client, const char *device)
 		return 4;
 	}
 
+	client->pcap_stat_timer.data = client;
+	client->pcap_stat_timer.cb = pcap_check_stats_cb;
+	pcap_check_stats_cb(client);
+
 	osmo_client_send_link(client);
 
 	if (client->filter_string) {
diff --git a/src/osmo_client_main.c b/src/osmo_client_main.c
index 0b53939..f5ba41a 100644
--- a/src/osmo_client_main.c
+++ b/src/osmo_client_main.c
@@ -62,6 +62,9 @@ static const struct rate_ctr_desc pcap_client_ctr_desc[] = {
 	[CLIENT_CTR_QERR]		= { "client.queue_err",		"Can not queue data    " },
 	[CLIENT_CTR_PERR]		= { "client.pcap_err",		"libpcap error         " },
 	[CLIENT_CTR_WERR]		= { "client.write_err",		"Write error           " },
+	[CLIENT_CTR_P_RECV]		= { "pcap.recv",		"PCAP received packets " },
+	[CLIENT_CTR_P_DROP]		= { "pcap.drop",		"PCAP dropped packets  " },
+	[CLIENT_CTR_P_IFDROP]		= { "pcap.ifdrop",		"iface dropped packets " },
 };
 
 static const struct rate_ctr_group_desc pcap_client_ctr_group_desc = {