VIRT-PHY: Added functionality to cooperate with osmocom-bb virt-phy.

This patch improves the virtual physical layer designed to replace the
air interface. The purpose is to get rid of the hardware requirements
and be able to start testing and implementing layer 2 communication
functionality on one machine. Multicast sockets are used to enable
bidirectional communication between the BTS and the MS process.
The GSMTAP protocol designed for wireshark capturing is used to
encapsulate the payload on the virtual physical layer.

* Working mcast socket communication and extraction of its 
  functionality.
* Fixed OML and RSL startup sequences.
* Icludes tests for mcast socket and virtual UM.
* Ecapsulation and parsing methods to and from GSMTAP messages.
* Basic handlers for file descriptor callbacks from incoming mcast
  messages.
* Multiplexing to different channels based on GSMTAP header channel
  type.

1 files changed, 72 insertions, 0 deletions

diff --git a/tests/virtsock/virt_um_ms.c b/tests/virtsock/virt_um_ms.c
new file mode 100644
index 00000000..ce061888
--- /dev/null
+++ b/tests/virtsock/virt_um_ms.c
@@ -0,0 +1,72 @@
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/select.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "../../src/osmo-bts-virtual/virtual_um.h"
+
+static char *tx_mcast_group = "224.0.0.1";
+static int tx_mcast_port = 6666;
+static char *rx_mcast_group = "225.0.0.1";
+static int rx_mcast_port = 6667;
+
+void virt_um_rx_cb(struct virt_um_inst *vui, struct msgb *msg)
+{
+	struct msgb *outmsg = msgb_alloc(VIRT_UM_MSGB_SIZE, "Virtual UM Rx");
+	char *data_loc, strbuf[VIRT_UM_MSGB_SIZE], addrbuf[32];
+	int rc, port;
+
+	inet_ntop(AF_INET, &vui->mcast_sock->rx_sock->mcast_group->imr_multiaddr, addrbuf, 32);
+
+	printf("Received MSG from BTS(%s): \"%s\"\n", addrbuf, msgb_data(msg));
+
+	sprintf(strbuf, "ACK: (%s)", msgb_data(msg));
+	data_loc = (char *)msgb_put(outmsg, strlen(strbuf)+1);
+	memcpy(data_loc, strbuf, strlen(strbuf)+1);
+
+	inet_ntop(AF_INET, &vui->mcast_sock->tx_sock->sock_conf->sin_addr, addrbuf, 32);
+	port = vui->mcast_sock->tx_sock->sock_conf->sin_port;
+	rc = virt_um_write_msg(vui, outmsg);
+	if (rc < 0) {
+		perror("Error sending ACK");
+	} else if (rc == 0) {
+		printf("Nothing sent: \"%s\"\n", msgb_data(outmsg));
+	} else {
+		printf("Sent ACK to BTS(%s:%d): \"%s\"\n", addrbuf, port, msgb_data(outmsg));
+	}
+}
+
+// main prog for a client program continuously receiving data from a multicast socket and responding to them answers on another
+int main(void)
+{
+	int i = 0;
+	struct virt_um_inst *vui = virt_um_init(NULL, tx_mcast_group,
+	                tx_mcast_port, rx_mcast_group, rx_mcast_port,
+	                virt_um_rx_cb);
+	if (!vui) {
+		perror("Error initializing vui.");
+	}
+	while (++i < 1000) {
+		printf("Waiting for MSG NR. %d\n", i);
+		osmo_select_main(0);
+		// fallback -> will the communication work without the fd callback?
+//		{
+//		char rx_buf[256], tx_buf[256];
+//		while(mcast_bidir_sock_rx(vui->mcast_sock, rx_buf, sizeof(rx_buf)) < 0) {
+//			perror("Error receiving message from server.");
+//		}
+//		printf("Received MSG from server: \"%s\"\n", rx_buf);
+//
+//		strcpy(tx_buf,"ACK: \"");
+//		strcat(tx_buf, rx_buf);
+//		strcat(tx_buf, "\"");
+//		if (mcast_bidir_sock_tx(vui->mcast_sock, tx_buf, sizeof(tx_buf)) < 0) {
+//			perror("Error transmitting message to server.");
+//		}
+//		printf("Sent ACK to server: \"%s\"\n", tx_buf);
+//		}
+	}
+	virt_um_destroy(vui);
+	return 0;
+}