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sdp: refactoring sdp parser/generator 

move SDP generator function write_response_sdp() from mgcp_protocol.c
to mgcp_sdp.c and use msgb_printf() instead of snprintf()

move prototypes for mgcp_parse_sdp_data() and mgcp_set_audio_info()
to mgcp_sdp.h

change parameter list of mgcp_parse_sdp_data() so that it takes the
rtp conn directly, rather than struct mgcp_rtp_end.

add doxygen comments to all public functions

Change-Id: I9f88c93872ff913bc211f560b26901267f577324
This commit is contained in:
Philipp Maier 2017-10-11 13:33:42 +02:00
parent 1e0b9f872c
commit 8970c497bc
5 changed files with 158 additions and 100 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/osmocom/mgcp/Makefile.am
View File

@ -4,4 +4,5 @@ noinst_HEADERS = \
mgcp_conn.h \
mgcp_stat.h \
mgcp_ep.h \
mgcp_sdp.h \
$(NULL)

3
include/osmocom/mgcp/mgcp_internal.h
View File

@ -317,9 +317,6 @@ enum {
#define DEFAULT_RTP_AUDIO_DEFAULT_CHANNELS 1
#define PTYPE_UNDEFINED (-1)
int mgcp_parse_sdp_data(struct mgcp_endpoint *endp, struct mgcp_rtp_end *rtp, struct mgcp_parse_data *p);
int mgcp_set_audio_info(void *ctx, struct mgcp_rtp_codec *codec,
int payload_type, const char *audio_name);
/*! get the ip-address where the mgw application is bound on.
* \param[in] endp mgcp endpoint, that holds a copy of the VTY parameters

35
include/osmocom/mgcp/mgcp_sdp.h Normal file
View File

@ -0,0 +1,35 @@
/*
* SDP generation and parsing
*
* (C) 2009-2015 by Holger Hans Peter Freyther <zecke@selfish.org>
* (C) 2009-2014 by On-Waves
* 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/>.
*
*/
#pragma once
#include <osmocom/mgcp/mgcp_sdp.h>
int mgcp_parse_sdp_data(const struct mgcp_endpoint *endp,
struct mgcp_conn_rtp *conn,
struct mgcp_parse_data *p);
int mgcp_set_audio_info(void *ctx, struct mgcp_rtp_codec *codec,
int payload_type, const char *audio_name);
int mgcp_write_response_sdp(const struct mgcp_endpoint *endp,
const struct mgcp_conn_rtp *conn, struct msgb *sdp,
const char *addr);

115
src/libosmo-mgcp/mgcp_protocol.c
View File

@ -39,6 +39,7 @@
#include <osmocom/mgcp/mgcp_stat.h>
#include <osmocom/mgcp/mgcp_msg.h>
#include <osmocom/mgcp/mgcp_ep.h>
#include <osmocom/mgcp/mgcp_sdp.h>
struct mgcp_request {
char *name;
@ -191,80 +192,6 @@ static struct msgb *create_err_response(struct mgcp_endpoint *endp,
return create_resp(endp, code, " FAIL", msg, trans, NULL, NULL);
}
static int write_response_sdp(struct mgcp_endpoint *endp,
struct mgcp_conn_rtp *conn,
char *sdp_record, size_t size, const char *addr)
{
const char *fmtp_extra;
const char *audio_name;
int payload_type;
int len;
int nchars;
if (!conn)
return -1;
endp->cfg->get_net_downlink_format_cb(endp, &payload_type,
&audio_name, &fmtp_extra, conn);
len = snprintf(sdp_record, size,
"v=0\r\n"
"o=- %u 23 IN IP4 %s\r\n"
"s=-\r\n"
"c=IN IP4 %s\r\n"
"t=0 0\r\n", conn->conn->id, addr, addr);
if (len < 0 || len >= size)
goto buffer_too_small;
if (payload_type >= 0) {
nchars = snprintf(sdp_record + len, size - len,
"m=audio %d RTP/AVP %d\r\n",
conn->end.local_port, payload_type);
if (nchars < 0 || nchars >= size - len)
goto buffer_too_small;
len += nchars;
if (audio_name && endp->tcfg->audio_send_name) {
nchars = snprintf(sdp_record + len, size - len,
"a=rtpmap:%d %s\r\n",
payload_type, audio_name);
if (nchars < 0 || nchars >= size - len)
goto buffer_too_small;
len += nchars;
}
if (fmtp_extra) {
nchars = snprintf(sdp_record + len, size - len,
"%s\r\n", fmtp_extra);
if (nchars < 0 || nchars >= size - len)
goto buffer_too_small;
len += nchars;
}
}
if (conn->end.packet_duration_ms > 0 && endp->tcfg->audio_send_ptime) {
nchars = snprintf(sdp_record + len, size - len,
"a=ptime:%u\r\n",
conn->end.packet_duration_ms);
if (nchars < 0 || nchars >= size - len)
goto buffer_too_small;
len += nchars;
}
return len;
buffer_too_small:
LOGP(DLMGCP, LOGL_ERROR, "SDP buffer too small: %zu (needed %d)\n",
size, len);
return -1;
}
/* Format MGCP response string (with SDP attached) */
static struct msgb *create_response_with_sdp(struct mgcp_endpoint *endp,
struct mgcp_conn_rtp *conn,
@ -272,11 +199,15 @@ static struct msgb *create_response_with_sdp(struct mgcp_endpoint *endp,
const char *trans_id)
{
const char *addr = endp->cfg->local_ip;
char sdp_record[4096];
int len;
int nchars;
struct msgb *sdp;
int rc;
struct msgb *result;
char osmux_extension[strlen("\nX-Osmux: 255") + 1];
sdp = msgb_alloc_headroom(4096, 128, "sdp record");
if (!sdp)
return NULL;
if (!addr)
addr = mgcp_net_src_addr(endp);
@ -287,21 +218,19 @@ static struct msgb *create_response_with_sdp(struct mgcp_endpoint *endp,
osmux_extension[0] = '\0';
}
len = snprintf(sdp_record, sizeof(sdp_record),
"I: %u%s\n\n", conn->conn->id, osmux_extension);
if (len < 0)
return NULL;
rc = msgb_printf(sdp, "I: %u%s\n\n", conn->conn->id, osmux_extension);
if (rc < 0)
goto error;
nchars = write_response_sdp(endp, conn, sdp_record + len,
sizeof(sdp_record) - len - 1, addr);
if (nchars < 0)
return NULL;
len += nchars;
sdp_record[sizeof(sdp_record) - 1] = '\0';
return create_resp(endp, 200, " OK", msg, trans_id, NULL, sdp_record);
rc = mgcp_write_response_sdp(endp, conn, sdp, addr);
if (rc < 0)
goto error;
result = create_resp(endp, 200, " OK", msg, trans_id, NULL, (char*) sdp->data);
msgb_free(sdp);
return result;
error:
msgb_free(sdp);
return NULL;
}
/* Send out dummy packet to keep the connection open, if the connection is an
@ -689,7 +618,7 @@ mgcp_header_done:
/* set up RTP media parameters */
if (have_sdp)
mgcp_parse_sdp_data(endp, &conn->end, p);
mgcp_parse_sdp_data(endp, conn, p);
else if (endp->local_options.codec)
mgcp_set_audio_info(p->cfg, &conn->end.codec,
PTYPE_UNDEFINED, endp->local_options.codec);
@ -836,7 +765,7 @@ mgcp_header_done:
conn->conn->mode = conn->conn->mode_orig;
if (have_sdp)
mgcp_parse_sdp_data(endp, &conn->end, p);
mgcp_parse_sdp_data(endp, conn, p);
set_local_cx_options(endp->tcfg->endpoints, &endp->local_options,
local_options);

104
src/libosmo-mgcp/mgcp_sdp.c
View File

@ -20,6 +20,7 @@
*
*/
#include <osmocom/core/msgb.h>
#include <osmocom/mgcp/mgcp.h>
#include <osmocom/mgcp/mgcp_internal.h>
#include <osmocom/mgcp/mgcp_msg.h>
@ -38,6 +39,12 @@ struct sdp_rtp_map {
int channels;
};
/*! Set codec configuration depending on payload type and codec name.
* \param[in] ctx talloc context.
* \param[out] codec configuration (caller provided memory).
* \param[in] payload_type codec type id (e.g. 3 for GSM, -1 when undefined).
* \param[in] audio_name audio codec name (e.g. "GSM/8000/1").
* \returns 0 on success, -1 on failure. */
int mgcp_set_audio_info(void *ctx, struct mgcp_rtp_codec *codec,
int payload_type, const char *audio_name)
{
@ -107,7 +114,7 @@ int mgcp_set_audio_info(void *ctx, struct mgcp_rtp_codec *codec,
return 0;
}
void codecs_initialize(void *ctx, struct sdp_rtp_map *codecs, int used)
static void codecs_initialize(void *ctx, struct sdp_rtp_map *codecs, int used)
{
int i;
@ -137,7 +144,8 @@ void codecs_initialize(void *ctx, struct sdp_rtp_map *codecs, int used)
}
}
void codecs_update(void *ctx, struct sdp_rtp_map *codecs, int used, int payload, char *audio_name)
static void codecs_update(void *ctx, struct sdp_rtp_map *codecs, int used,
int payload, const char *audio_name)
{
int i;
@ -163,7 +171,9 @@ void codecs_update(void *ctx, struct sdp_rtp_map *codecs, int used, int payload,
LOGP(DLMGCP, LOGL_ERROR, "Unconfigured PT(%d) with %s\n", payload, audio_name);
}
int is_codec_compatible(struct mgcp_endpoint *endp, struct sdp_rtp_map *codec)
/* Check if the codec matches what is set up in the trunk config */
static int is_codec_compatible(const struct mgcp_endpoint *endp,
const struct sdp_rtp_map *codec)
{
char *bts_codec;
char audio_codec[64];
@ -182,7 +192,17 @@ int is_codec_compatible(struct mgcp_endpoint *endp, struct sdp_rtp_map *codec)
return strcasecmp(audio_codec, codec->codec_name) == 0;
}
int mgcp_parse_sdp_data(struct mgcp_endpoint *endp, struct mgcp_rtp_end *rtp, struct mgcp_parse_data *p)
/*! Analyze SDP input string.
* \param[in] endp trunk endpoint.
* \param[out] conn associated rtp connection.
* \param[out] caller provided memory to store the parsing results.
* \returns 0 on success, -1 on failure.
*
* Note: In conn (conn->end) the function returns the packet duration,
* the rtp port and the rtcp port */
int mgcp_parse_sdp_data(const struct mgcp_endpoint *endp,
struct mgcp_conn_rtp *conn,
struct mgcp_parse_data *p)
{
struct sdp_rtp_map codecs[10];
int codecs_used = 0;
@ -191,7 +211,13 @@ int mgcp_parse_sdp_data(struct mgcp_endpoint *endp, struct mgcp_rtp_end *rtp, st
int i;
int codecs_assigned = 0;
void *tmp_ctx = talloc_new(NULL);
struct mgcp_rtp_end *rtp;
OSMO_ASSERT(endp);
OSMO_ASSERT(conn);
OSMO_ASSERT(p);
rtp = &conn->end;
memset(&codecs, 0, sizeof(codecs));
for_each_line(line, p->save) {
@ -304,3 +330,73 @@ int mgcp_parse_sdp_data(struct mgcp_endpoint *endp, struct mgcp_rtp_end *rtp, st
return codecs_assigned > 0;
}
/*! Generate SDP response string.
* \param[in] endp trunk endpoint.
* \param[in] conn associated rtp connection.
* \param[out] sdp msg buffer to append resulting SDP string data.
* \param[in] addr IPV4 address string (e.g. 192.168.100.1).
* \returns 0 on success, -1 on failure. */
int mgcp_write_response_sdp(const struct mgcp_endpoint *endp,
const struct mgcp_conn_rtp *conn, struct msgb *sdp,
const char *addr)
{
const char *fmtp_extra;
const char *audio_name;
int payload_type;
int rc;
OSMO_ASSERT(endp);
OSMO_ASSERT(conn);
OSMO_ASSERT(sdp);
OSMO_ASSERT(addr);
/* FIXME: constify endp and conn args in get_net_donwlink_format_cb() */
endp->cfg->get_net_downlink_format_cb((struct mgcp_endpoint *)endp,
&payload_type, &audio_name,
&fmtp_extra,
(struct mgcp_conn_rtp *)conn);
rc = msgb_printf(sdp,
"v=0\r\n"
"o=- %u 23 IN IP4 %s\r\n"
"s=-\r\n"
"c=IN IP4 %s\r\n"
"t=0 0\r\n", conn->conn->id, addr, addr);
if (rc < 0)
goto buffer_too_small;
if (payload_type >= 0) {
rc = msgb_printf(sdp, "m=audio %d RTP/AVP %d\r\n",
conn->end.local_port, payload_type);
if (rc < 0)
goto buffer_too_small;
if (audio_name && endp->tcfg->audio_send_name) {
rc = msgb_printf(sdp, "a=rtpmap:%d %s\r\n",
payload_type, audio_name);
if (rc < 0)
goto buffer_too_small;
}
if (fmtp_extra) {
rc = msgb_printf(sdp, "%s\r\n", fmtp_extra);
if (rc < 0)
goto buffer_too_small;
}
}
if (conn->end.packet_duration_ms > 0 && endp->tcfg->audio_send_ptime) {
rc = msgb_printf(sdp, "a=ptime:%u\r\n",
conn->end.packet_duration_ms);
if (rc < 0)
goto buffer_too_small;
}
return 0;
buffer_too_small:
LOGP(DLMGCP, LOGL_ERROR, "SDP messagebuffer too small\n");
return -1;
}