224 lines
6.6 KiB
C
224 lines
6.6 KiB
C
/* A Media Gateway Control Protocol Media Gateway: RFC 3435 */
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/* IuUP Core Network side protocol handling, minimal implementation */
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/*
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* (C) 2018 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
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* All Rights Reserved
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*
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* Author: Neels Hofmeyr <neels@hofmeyr.de>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include <talloc.h>
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#include <errno.h>
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#include <string.h>
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#include <arpa/inet.h>
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#include <osmocom/core/utils.h>
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#include <osmocom/core/logging.h>
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#include <osmocom/core/msgb.h>
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#include <osmocom/netif/rtp.h>
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#include <osmocom/mgcp/iuup_cn_node.h>
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#include <osmocom/mgcp/iuup_protocol.h>
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#include <osmocom/mgcp/debug.h>
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#define LOG_IUUP_CN(cn, level, fmt, args...) \
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LOGP(DIUUP, level, "(%s) " fmt, (cn)->name, ## args)
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#define AMR_HEADER_LENGTH 2
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#define AMR_COMFORT_NOISE_PAYLOAD_LENGTH 5
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struct osmo_iuup_cn {
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struct osmo_iuup_cn_cfg cfg;
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char *name;
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uint8_t next_frame_nr;
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int rtp_payload_type;
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};
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struct osmo_iuup_cn *osmo_iuup_cn_init(void *ctx, struct osmo_iuup_cn_cfg *cfg,
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const char *name_fmt, ...)
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{
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va_list ap;
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struct osmo_iuup_cn *cn = talloc_zero(ctx, struct osmo_iuup_cn);
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OSMO_ASSERT(cn);
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cn->cfg = *cfg;
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if (!name_fmt)
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name_fmt = "-";
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va_start(ap, name_fmt);
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cn->name = talloc_vasprintf(cn, name_fmt, ap);
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va_end(ap);
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LOGP(DIUUP, LOGL_INFO, "(%s) Initializing IuUP node\n", cn->name);
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if (!osmo_identifier_valid(cn->name)) {
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LOGP(DIUUP, LOGL_ERROR, "Attempting to set illegal id for IuUP CN instance: %s\n",
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osmo_quote_str(cn->name, -1));
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talloc_free(cn);
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return NULL;
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}
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return cn;
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}
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void osmo_iuup_cn_free(struct osmo_iuup_cn *cn)
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{
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talloc_free(cn);
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}
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static int rx_data(struct osmo_iuup_cn *cn, struct msgb *pdu,
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struct osmo_iuup_hdr_data *hdr)
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{
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/* Strip the IuUP bits from the middle of the buffer by writing the RTP
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* header forward by the length of IuUP header minus the length of AMR
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* header. Replace the rest of IuUP header with AMR header */
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unsigned int pre_hdr_len = ((uint8_t*)hdr) - pdu->data;
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int is_comfort_noise = ((pdu->len - pre_hdr_len - sizeof(*hdr)) == AMR_COMFORT_NOISE_PAYLOAD_LENGTH);
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memmove(pdu->data + sizeof(*hdr) - AMR_HEADER_LENGTH, pdu->data, pre_hdr_len);
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((uint8_t*)hdr)[2] = 0x70;
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((uint8_t*)hdr)[3] = is_comfort_noise ? 0x44 : 0x3c;
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msgb_pull(pdu, sizeof(*hdr) - AMR_HEADER_LENGTH);
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LOGP(DIUUP, LOGL_DEBUG, "(%s) IuUP stripping IuUP header from RTP data\n", cn->name);
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cn->cfg.rx_payload(pdu, cn->cfg.node_priv);
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return 0;
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}
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static int tx_init_ack(struct osmo_iuup_cn *cn, struct msgb *src_pdu)
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{
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/* Send Initialization Ack PDU back to the sender */
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int rc;
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struct msgb *ack = msgb_alloc(4096, "IuUP Initialization Ack");
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OSMO_ASSERT(ack);
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ack->dst = src_pdu->dst;
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/* Just copy the RTP header that was sent... TODO: tweak some RTP values?? */
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memcpy(msgb_put(ack, sizeof(struct rtp_hdr)), src_pdu->data, sizeof(struct rtp_hdr));
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osmo_iuup_make_init_ack(ack);
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LOGP(DIUUP, LOGL_DEBUG, "(%s) Sending Initialization ACK %p\n", cn->name, cn->cfg.node_priv);
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rc = cn->cfg.tx_msg(ack, cn->cfg.node_priv);
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msgb_free(ack);
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return rc;
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}
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static int rx_control(struct osmo_iuup_cn *cn, struct msgb *pdu,
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struct osmo_iuup_hdr_ctrl *hdr)
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{
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switch (hdr->procedure) {
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case OSMO_IUUP_PROC_INITIALIZATION:
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switch (hdr->ack_nack) {
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case OSMO_IUUP_ACKNACK_PROCEDURE:
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LOGP(DIUUP, LOGL_INFO, "(%s) Rx IuUP Initialization, sending ACK\n", cn->name);
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cn->rtp_payload_type = ((struct rtp_hdr*)pdu->data)->payload_type;
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return tx_init_ack(cn, pdu);
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default:
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LOGP(DIUUP, LOGL_DEBUG, "(%s) Rx IuUP Initialization, unhandled ack_nack = %d\n",
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cn->name, hdr->ack_nack);
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break;
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}
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/* Continue to log "unexpected procedure" below. */
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break;
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case OSMO_IUUP_PROC_ERROR_EVENT:
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{
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union osmo_iuup_hdr_ctrl_payload *p = (void*)hdr->payload;
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LOGP(DIUUP, LOGL_ERROR,
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"(%s) Rx IuUP Error Event: distance=%u, cause=%u=\"%s\"\n",
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cn->name, p->error_event.error_distance, p->error_event.error_cause,
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osmo_iuup_error_cause_name(p->error_event.error_cause));
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return 0;
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}
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default:
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break;
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}
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LOG_IUUP_CN(cn, LOGL_ERROR,
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"Rx control PDU with unexpected procedure: 0x%x acknack=0x%x\n",
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hdr->procedure, hdr->ack_nack);
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return -EINVAL;
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}
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/* Feed a received PDU to the IuUP CN node. This function takes ownership of the msgb, it must not be
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* freed by the caller. */
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int osmo_iuup_cn_rx_pdu(struct osmo_iuup_cn *cn, struct msgb *pdu)
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{
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struct osmo_iuup_hdr_ctrl *is_ctrl;
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struct osmo_iuup_hdr_data *is_data;
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int rc;
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rc = osmo_iuup_classify(true, cn->name, pdu, &is_ctrl, &is_data);
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if (rc)
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return rc;
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if (is_ctrl)
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return rx_control(cn, pdu, is_ctrl);
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if (is_data)
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return rx_data(cn, pdu, is_data);
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return rc;
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}
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static uint8_t next_frame_nr(struct osmo_iuup_cn *cn)
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{
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uint8_t frame_nr = cn->next_frame_nr;
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cn->next_frame_nr = (frame_nr + 1) & 0x0f;
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return frame_nr;
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}
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/* Send this RTP packet to the IuUP peer: add IuUP header and call the tx_msg() to transmit the resulting
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* message to the IuUP peer.
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* Returns 0 on success, negative on error. */
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int osmo_iuup_cn_tx_payload(struct osmo_iuup_cn *cn, struct msgb *pdu)
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{
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struct rtp_hdr *rtp_was, *rtp;
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struct osmo_iuup_hdr_data *iuup_hdr;
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/* Splice an IuUP header in between RTP header and payload data */
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rtp_was = (void*)pdu->data;
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/* copy the RTP header part backwards by the size needed for the IuUP header
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* minus AMR header bytes from the front of RTP payload */
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rtp = (void*)msgb_push(pdu, sizeof(*iuup_hdr) - AMR_HEADER_LENGTH);
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memmove(rtp, rtp_was, sizeof(*rtp));
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/* Send the same payload type to the peer (erm...) */
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rtp->payload_type = cn->rtp_payload_type;
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iuup_hdr = (void*)rtp->data;
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*iuup_hdr = (struct osmo_iuup_hdr_data){
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.pdu_type = OSMO_IUUP_PDU_DATA_WITH_CRC,
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.frame_nr = next_frame_nr(cn),
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.frame_good = OSMO_IUUP_FRAME_GOOD,
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};
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osmo_iuup_set_checksums((uint8_t*)iuup_hdr, pdu->tail - (uint8_t*)iuup_hdr);
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LOGP(DIUUP, LOGL_DEBUG, "(%s) IuUP inserting IuUP header in RTP data (frame nr %u)\n",
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cn->name, iuup_hdr->frame_nr);
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return cn->cfg.tx_msg(pdu, cn->cfg.node_priv);
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}
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