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Re-introduce support for IPA-encapsulated MGCP 

Old osmo-bsc-sccplite already supported this, but in the migration
over to libosmo-sigtran and to real 3GPP AoIP, this functionality
got lost.

We now crate a UDP proxy socket. Any MGCP commands received via IPA
from MSC (or rather: bsc_nat) are retransmitted to the MGW via UDP on
this socket.  Any responses back from the MGW received on the UDP
socket are retransmitted back to MSC/bsc_nat as MGCP inside the IPA
multiplex.

Closes: OS#2536
Change-Id: I38ad8fa645c08900e0e1f1b4b96136bc6d96b3ab
This commit is contained in:
Harald Welte 2018-05-26 22:56:59 +02:00
parent 7ae0f9c271
commit ba6c93d3c4
7 changed files with 186 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
include/osmocom/bsc/bsc_msc_data.h
View File

@ -31,6 +31,7 @@
#include "debug.h"
#include <osmocom/core/timer.h>
#include <osmocom/core/select.h>
#include <osmocom/gsm/protocol/gsm_04_08.h>
@ -140,6 +141,16 @@ struct bsc_msc_data {
uint32_t x_osmo_ign;
bool x_osmo_ign_configured;
/* Proxy between IPA/SCCPlite encapsulated MGCP and UDP */
struct {
/* local (BSC) IP address to be used */
char *local_addr;
/* local (BSC) UDP port to be usd to talk with MGW */
uint16_t local_port;
/* UDP socket for proxying MGCP via SCCPlite/IPA */
struct osmo_fd ofd;
} mgcp_ipa;
};
/*

9
include/osmocom/bsc/osmo_bsc_sigtran.h
View File

@ -44,3 +44,12 @@ void osmo_bsc_sigtran_tx_reset_ack(const struct bsc_msc_data *msc);
/* receive + process a CTRL command from the piggy-back on the IPA/SCCPlite link */
int bsc_sccplite_rx_ctrl(struct osmo_ss7_asp *asp, struct msgb *msg);
/* receive + process a MGCP message from the piggy-back on the IPA/SCCPlite link */
int bsc_sccplite_rx_mgcp(struct osmo_ss7_asp *asp, struct msgb *msg);
/* send a message via SCCPLite to given MSC */
int bsc_sccplite_msc_send(struct bsc_msc_data *msc, struct msgb *msg);
/* we received some data on the UDP proxy socket from the MGW. Pass it to MSC via IPA */
int bsc_sccplite_mgcp_proxy_cb(struct osmo_fd *ofd, unsigned int what);

1
src/osmo-bsc/Makefile.am
View File

@ -81,6 +81,7 @@ osmo_bsc_SOURCES = \
osmo_bsc_grace.c \
osmo_bsc_lcls.c \
osmo_bsc_main.c \
osmo_bsc_mgcp.c \
osmo_bsc_msc.c \
osmo_bsc_sigtran.c \
osmo_bsc_vty.c \

59
src/osmo-bsc/osmo_bsc_ctrl.c
View File

@ -52,6 +52,39 @@ static struct osmo_ss7_as *msc_get_ss7_as(struct bsc_msc_data *msc)
return rt->dest.as;
}
static int _ss7_as_send(struct osmo_ss7_as *as, struct msgb *msg)
{
struct osmo_ss7_asp *asp;
unsigned int i;
/* FIXME: unify with xua_as_transmit_msg() and perform proper ASP lookup */
for (i = 0; i < ARRAY_SIZE(as->cfg.asps); i++) {
asp = as->cfg.asps[i];
if (!asp)
continue;
/* FIXME: deal with multiple ASPs per AS */
return osmo_ss7_asp_send(asp, msg);
}
msgb_free(msg);
return -1;
}
int bsc_sccplite_msc_send(struct bsc_msc_data *msc, struct msgb *msg)
{
struct osmo_ss7_as *as;
as = msc_get_ss7_as(msc);
if (!as) {
msgb_free(msg);
return -1;
}
/* don't attempt to send CTRL on a non-SCCPlite AS */
if (as->cfg.proto != OSMO_SS7_ASP_PROT_IPA)
return 0;
return _ss7_as_send(as, msg);
}
/* Encode a CTRL command and send it to the given ASP
* \param[in] asp ASP through which we shall send the encoded message
@ -83,30 +116,20 @@ static int sccplite_asp_ctrl_cmd_send(struct osmo_ss7_asp *asp, struct ctrl_cmd
* Caller must hence free 'cmd' itself. */
static int sccplite_msc_ctrl_cmd_send(struct bsc_msc_data *msc, struct ctrl_cmd *cmd)
{
struct osmo_ss7_as *as;
struct osmo_ss7_asp *asp;
unsigned int i;
struct msgb *msg;
as = msc_get_ss7_as(msc);
if (!as)
msg = ctrl_cmd_make(cmd);
if (!msg)
return -1;
/* don't attempt to send CTRL on a non-SCCPlite AS */
if (as->cfg.proto != OSMO_SS7_ASP_PROT_IPA)
return 0;
ipa_prepend_header_ext(msg, IPAC_PROTO_EXT_CTRL);
ipa_prepend_header(msg, IPAC_PROTO_OSMO);
/* FIXME: unify with xua_as_transmit_msg() and perform proper ASP lookup */
for (i = 0; i < ARRAY_SIZE(as->cfg.asps); i++) {
asp = as->cfg.asps[i];
if (!asp)
continue;
/* FIXME: deal with multiple ASPs per AS */
return sccplite_asp_ctrl_cmd_send(asp, cmd);
}
return -1;
return bsc_sccplite_msc_send(msc, msg);
}
/* receive + process a CTRL command from the piggy-back on the IPA/SCCPlite link */
/* receive + process a CTRL command from the piggy-back on the IPA/SCCPlite link.
* Transfers msg ownership. */
int bsc_sccplite_rx_ctrl(struct osmo_ss7_asp *asp, struct msgb *msg)
{
struct ctrl_cmd *cmd;

91
src/osmo-bsc/osmo_bsc_mgcp.c Normal file
View File

@ -0,0 +1,91 @@
/*
* SCCPlite MGCP handling
*
* (C) 2018 by Harald Welte <laforge@gnumonks.org>
* All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include <osmocom/bsc/bsc_msc_data.h>
#include <osmocom/bsc/osmo_bsc.h>
#include <osmocom/bsc/gsm_data.h>
#include <osmocom/bsc/debug.h>
#include <osmocom/gsm/ipa.h>
#include <osmocom/gsm/protocol/ipaccess.h>
#include <osmocom/bsc/osmo_bsc_sigtran.h>
#include <arpa/inet.h>
/* Determine MSC based on the ASP over which the message was received */
static struct bsc_msc_data *msc_from_asp(struct osmo_ss7_asp *asp)
{
int msc_nr;
/* this is rather ugly, as we of course have MTP-level routing between
* the local SCCP user (BSC) and the AS/ASPs. However, for the most simple
* SCCPlite case, there is a 1:1 mapping between ASP and AS, and using
* the libosmo-sigtran "simple client", the names are "as[p]-clnt-msc-%u",
* as set in osmo_bsc_sigtran_init() */
if (sscanf(asp->cfg.name, "asp-clnt-msc-%u", &msc_nr) != 1) {
LOGP(DMSC, LOGL_ERROR, "Cannot find to which MSC the ASP %s belongs\n", asp->cfg.name);
return NULL;
}
return osmo_msc_data_find(bsc_gsmnet, msc_nr);
}
/* We received an IPA-encapsulated MGCP message from a MSC. Transfers msg ownership. */
int bsc_sccplite_rx_mgcp(struct osmo_ss7_asp *asp, struct msgb *msg)
{
struct bsc_msc_data *msc;
int rc;
LOGP(DMSC, LOGL_NOTICE, "%s: Received IPA-encapsulated MGCP: %s\n", asp->cfg.name, msg->l2h);
msc = msc_from_asp(asp);
if (msc) {
/* we don't have a write queue here as we simply expect the socket buffers
* to be large enouhg to deal with whatever small/infrequent MGCP messages */
rc = send(msc->mgcp_ipa.ofd.fd, msgb_l2(msg), msgb_l2len(msg), 0);
} else
rc = 0;
msgb_free(msg);
return rc;
}
/* we received some data on the UDP proxy socket from the MGW. Pass it to MSC via IPA */
int bsc_sccplite_mgcp_proxy_cb(struct osmo_fd *ofd, unsigned int what)
{
struct bsc_msc_data *msc = ofd->data;
struct msgb *msg;
int rc;
if (!(what & BSC_FD_READ))
return 0;
msg = msgb_alloc_headroom(1024, 16, "MGCP->IPA");
OSMO_ASSERT(msg);
rc = recv(ofd->fd, msg->data, msgb_tailroom(msg), 0);
if (rc <= 0) {
LOGP(DMSC, LOGL_ERROR, "error receiving data from MGCP<-> IPA proxy UDP socket: "
"%s\n", strerror(errno));
msgb_free(msg);
return rc;
}
msg->l2h = msgb_put(msg, rc);
LOGP(DMSC, LOGL_NOTICE, "Received MGCP on UDP proxy socket: %s\n", msg->l2h);
ipa_prepend_header(msg, IPAC_PROTO_MGCP_OLD);
return bsc_sccplite_msc_send(msc, msg);
}

31
src/osmo-bsc/osmo_bsc_msc.c
View File

@ -27,26 +27,49 @@
#include <osmocom/bsc/gsm_data.h>
#include <osmocom/bsc/ipaccess.h>
#include <osmocom/bsc/bsc_msc_data.h>
#include <osmocom/bsc/osmo_bsc_sigtran.h>
#include <osmocom/bsc/signal.h>
#include <osmocom/core/talloc.h>
#include <osmocom/core/socket.h>
#include <osmocom/gsm/gsm0808.h>
#include <osmocom/abis/ipa.h>
#include <osmocom/mgcp_client/mgcp_client.h>
#include <sys/socket.h>
#include <netinet/tcp.h>
#include <unistd.h>
int osmo_bsc_msc_init(struct bsc_msc_data *data)
int osmo_bsc_msc_init(struct bsc_msc_data *msc)
{
struct gsm_network *net = msc->network;
uint16_t mgw_port;
int rc;
/* FIXME: This is a leftover from the old architecture that used
* sccp-lite with osmocom specific authentication. Since we now
* changed to AoIP the connected status and the authentication
* status is managed differently. However osmo_bsc_filter.c still
* needs the flags to be set to one. See also: OS#3112 */
data->is_authenticated = 1;
msc->is_authenticated = 1;
if (net->mgw.conf->remote_port == -1)
mgw_port = 2427;
else
mgw_port = net->mgw.conf->remote_port;
rc = osmo_sock_init2_ofd(&msc->mgcp_ipa.ofd, AF_INET, SOCK_DGRAM, IPPROTO_UDP,
msc->mgcp_ipa.local_addr, msc->mgcp_ipa.local_port,
net->mgw.conf->remote_addr, mgw_port,
OSMO_SOCK_F_BIND | OSMO_SOCK_F_CONNECT);
if (rc < 0) {
LOGP(DMSC, LOGL_ERROR, "msc %u: Could not create/connect/bind MGCP proxy socket: %d\n",
msc->nr, rc);
return rc;
}
return 0;
}
@ -116,6 +139,10 @@ struct bsc_msc_data *osmo_msc_data_alloc(struct gsm_network *net, int nr)
msc_data->audio_support[4]->ver = 3;
msc_data->audio_support[4]->hr = 1;
osmo_fd_setup(&msc_data->mgcp_ipa.ofd, -1, BSC_FD_READ, &bsc_sccplite_mgcp_proxy_cb, msc_data, 0);
msc_data->mgcp_ipa.local_addr = talloc_strdup(msc_data, "0.0.0.0");
msc_data->mgcp_ipa.local_port = 0; /* dynamic */
return msc_data;
}

4
src/osmo-bsc/osmo_bsc_sigtran.c
View File

@ -593,8 +593,12 @@ static int asp_rx_unknown(struct osmo_ss7_asp *asp, int ppid_mux, struct msgb *m
switch (iph_ext->proto) {
case IPAC_PROTO_EXT_CTRL:
return bsc_sccplite_rx_ctrl(asp, msg);
case IPAC_PROTO_EXT_MGCP:
return bsc_sccplite_rx_mgcp(asp, msg);
}
break;
case IPAC_PROTO_MGCP_OLD:
return bsc_sccplite_rx_mgcp(asp, msg);
default:
break;
}