From 57e95a22f02b5b2ec781d9bc977c785a6e6f1166 Mon Sep 17 00:00:00 2001
From: Pablo Neira Ayuso <pablo@soleta.eu>
Date: Fri, 17 Jul 2015 21:56:23 +0200
Subject: osmux: add option to pad the circuit with dummy messages

Iridium is a satellite network which operates a GPRS-like that allows you to
get speeds up to 128kbit/s. However, it takes from 5 to 6 secs to get the
bandwidth allocated, so the conversation is garbled during the time.

This patch uses the new dummy padding support in libosmo-netif that is
controlled through the osmux osmux_xfrm_input_open_circuit().

This includes a new VTY option for osmux.
---
 openbsc/include/openbsc/mgcp.h   |  4 ++++
 openbsc/src/libmgcp/mgcp_osmux.c |  7 +++++++
 openbsc/src/libmgcp/mgcp_vty.c   | 16 ++++++++++++++++
 3 files changed, 27 insertions(+)

diff --git a/openbsc/include/openbsc/mgcp.h b/openbsc/include/openbsc/mgcp.h
index fb16cb40f..9befa7c7e 100644
--- a/openbsc/include/openbsc/mgcp.h
+++ b/openbsc/include/openbsc/mgcp.h
@@ -227,6 +227,10 @@ struct mgcp_config {
 	int osmux_batch_size;
 	/* osmux port */
 	uint16_t osmux_port;
+	/* Pad circuit with dummy messages until we see the first voice
+	 * message.
+	 */
+	uint16_t osmux_dummy;
 };
 
 /* config management */
diff --git a/openbsc/src/libmgcp/mgcp_osmux.c b/openbsc/src/libmgcp/mgcp_osmux.c
index 7f61173a1..90b73680b 100644
--- a/openbsc/src/libmgcp/mgcp_osmux.c
+++ b/openbsc/src/libmgcp/mgcp_osmux.c
@@ -462,6 +462,12 @@ int osmux_enable_endpoint(struct mgcp_endpoint *endp, int role,
 		LOGP(DMGCP, LOGL_ERROR, "Cannot allocate input osmux handle\n");
 		return -1;
 	}
+	if (!osmux_xfrm_input_open_circuit(endp->osmux.in, endp->osmux.cid,
+					   endp->cfg->osmux_dummy)) {
+		LOGP(DMGCP, LOGL_ERROR, "Cannot open osmux circuit %u\n",
+		     endp->osmux.cid);
+		return -1;
+	}
 
 	switch (endp->cfg->role) {
 		case MGCP_BSC_NAT:
@@ -480,6 +486,7 @@ void osmux_disable_endpoint(struct mgcp_endpoint *endp)
 {
 	LOGP(DMGCP, LOGL_INFO, "Releasing endpoint %u using Osmux CID %u\n",
 	     ENDPOINT_NUMBER(endp), endp->osmux.cid);
+	osmux_xfrm_input_close_circuit(endp->osmux.in, endp->osmux.cid);
 	endp->osmux.state = OSMUX_STATE_DISABLED;
 	endp->osmux.cid = -1;
 	osmux_handle_put(endp->osmux.in);
diff --git a/openbsc/src/libmgcp/mgcp_vty.c b/openbsc/src/libmgcp/mgcp_vty.c
index dd21a1537..8f6b10ab4 100644
--- a/openbsc/src/libmgcp/mgcp_vty.c
+++ b/openbsc/src/libmgcp/mgcp_vty.c
@@ -144,6 +144,8 @@ static int config_write_mgcp(struct vty *vty)
 			g_cfg->osmux_batch_size, VTY_NEWLINE);
 		vty_out(vty, "  osmux port %u%s",
 			g_cfg->osmux_port, VTY_NEWLINE);
+		vty_out(vty, "  osmux dummy %s%s",
+			g_cfg->osmux_dummy ? "on" : "off", VTY_NEWLINE);
 	}
 	return CMD_SUCCESS;
 }
@@ -1245,6 +1247,19 @@ DEFUN(cfg_mgcp_osmux_port,
 	return CMD_SUCCESS;
 }
 
+DEFUN(cfg_mgcp_osmux_dummy,
+      cfg_mgcp_osmux_dummy_cmd,
+      "osmux dummy (on|off)",
+      OSMUX_STR "Enable dummy padding\n" "Disable dummy padding\n")
+{
+	if (strcmp(argv[0], "on") == 0)
+		g_cfg->osmux_dummy = 1;
+	else if (strcmp(argv[0], "off") == 0)
+		g_cfg->osmux_dummy = 0;
+
+	return CMD_SUCCESS;
+}
+
 int mgcp_vty_init(void)
 {
 	install_element_ve(&show_mgcp_cmd);
@@ -1304,6 +1319,7 @@ int mgcp_vty_init(void)
 	install_element(MGCP_NODE, &cfg_mgcp_osmux_batch_factor_cmd);
 	install_element(MGCP_NODE, &cfg_mgcp_osmux_batch_size_cmd);
 	install_element(MGCP_NODE, &cfg_mgcp_osmux_port_cmd);
+	install_element(MGCP_NODE, &cfg_mgcp_osmux_dummy_cmd);
 	install_element(MGCP_NODE, &cfg_mgcp_allow_transcoding_cmd);
 	install_element(MGCP_NODE, &cfg_mgcp_no_allow_transcoding_cmd);
 
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