Add vty cmd 'cdr trap' to send CDR through CTRL iface

Default behavior is to have them disabled, and can be explicitly
disabled too by using 'no cdr trap' cmd.

Tested with osmo_ctrl.py that messages are send successfully:
TRAP 0 cdr-v1 20171129125950222,901700000015254,357737055592090,555,0,5,,pdp-periodic,2731,127.0.0.2,127.0.0.1,internet,176.16.222.3,20793,10045,1

Related: OS#2360

Change-Id: I1d144d87effd934d991257a65e19cf046a938907
diff --git a/src/gprs/sgsn_vty.c b/src/gprs/sgsn_vty.c
index a01de2d..c8dfc43 100644
--- a/src/gprs/sgsn_vty.c
+++ b/src/gprs/sgsn_vty.c
@@ -233,6 +233,10 @@
 		vty_out(vty, " cdr filename %s%s", g_cfg->cdr.filename, VTY_NEWLINE);
 	else
 		vty_out(vty, " no cdr filename%s", VTY_NEWLINE);
+	if (g_cfg->cdr.trap)
+		vty_out(vty, " cdr trap%s", VTY_NEWLINE);
+	else
+		vty_out(vty, " no cdr trap%s", VTY_NEWLINE);
 	vty_out(vty, " cdr interval %d%s", g_cfg->cdr.interval, VTY_NEWLINE);
 
 	vty_out(vty, " timer t3312 %d%s", g_cfg->timers.T3312, VTY_NEWLINE);
@@ -1100,7 +1104,7 @@
 
 DEFUN(cfg_cdr_filename, cfg_cdr_filename_cmd,
 	"cdr filename NAME",
-	"CDR\nSet filename\nname\n")
+	"CDR\nEnable saving CDR to filename\nname\n")
 {
 	talloc_free(g_cfg->cdr.filename);
 	g_cfg->cdr.filename = talloc_strdup(tall_vty_ctx, argv[0]);
@@ -1109,13 +1113,29 @@
 
 DEFUN(cfg_no_cdr_filename, cfg_no_cdr_filename_cmd,
 	"no cdr filename",
-	NO_STR "CDR\nDisable CDR generation\n")
+	NO_STR "CDR\nDisable saving CDR to file\n")
 {
 	talloc_free(g_cfg->cdr.filename);
 	g_cfg->cdr.filename = NULL;
 	return CMD_SUCCESS;
 }
 
+DEFUN(cfg_cdr_trap, cfg_cdr_trap_cmd,
+	"cdr trap",
+	"CDR\nEnable sending CDR via TRAP CTRL messages\n")
+{
+	g_cfg->cdr.trap = true;
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_no_cdr_trap, cfg_no_cdr_trap_cmd,
+	"no cdr trap",
+	NO_STR "CDR\nDisable sending CDR via TRAP CTRL messages\n")
+{
+	g_cfg->cdr.trap = false;
+	return CMD_SUCCESS;
+}
+
 DEFUN(cfg_cdr_interval, cfg_cdr_interval_cmd,
 	"cdr interval <1-2147483647>",
 	"CDR\nPDP periodic log interval\nSeconds\n")
@@ -1250,6 +1270,8 @@
 	install_element(SGSN_NODE, &cfg_no_apn_name_cmd);
 	install_element(SGSN_NODE, &cfg_cdr_filename_cmd);
 	install_element(SGSN_NODE, &cfg_no_cdr_filename_cmd);
+	install_element(SGSN_NODE, &cfg_cdr_trap_cmd);
+	install_element(SGSN_NODE, &cfg_no_cdr_trap_cmd);
 	install_element(SGSN_NODE, &cfg_cdr_interval_cmd);
 	install_element(SGSN_NODE, &cfg_ggsn_dynamic_lookup_cmd);
 	install_element(SGSN_NODE, &cfg_grx_ggsn_cmd);