e1_line.c: Split multiplex + demultiplex into separate mux_demux.c

The remaining intf_line.c really only manages the data structures.

This is useful for building other programs than osmo-e1d, such as
an upcoming E1 test utility called osmo-e1gen which will also use
the USB interface and icE1usb hardware, but not any of the mux/demux/ctl
code.

Change-Id: I1ceaea85a15e2fae1d2e041173be9d758c6d0b78

1 files changed, 377 insertions, 0 deletions

diff --git a/src/mux_demux.c b/src/mux_demux.c
new file mode 100644
index 0000000..ed7bf3b
--- /dev/null
+++ b/src/mux_demux.c
@@ -0,0 +1,377 @@
+/*
+ * mux_demux.c
+ *
+ * (C) 2019 by Sylvain Munaut <tnt@246tNt.com>
+ *
+ * All Rights Reserved
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <errno.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+
+#include <talloc.h>
+
+#include <osmocom/core/isdnhdlc.h>
+#include <osmocom/core/utils.h>
+#include <osmocom/core/stats.h>
+#include <osmocom/core/rate_ctr.h>
+#include <osmocom/e1d/proto.h>
+
+#include "e1d.h"
+#include "log.h"
+
+// ---------------------------------------------------------------------------
+// data transfer
+// ---------------------------------------------------------------------------
+
+static int
+_e1_rx_hdlcfs(struct e1_ts *ts, const uint8_t *buf, int len)
+{
+	int rv, cl, oi;
+
+	oi = 0;
+
+	while (oi < len) {
+		rv = osmo_isdnhdlc_decode(&ts->hdlc.rx,
+			&buf[oi], len-oi, &cl,
+			ts->hdlc.rx_buf, sizeof(ts->hdlc.rx_buf)
+		);
+
+		if (rv > 0) {
+			int bytes_to_write = rv;
+			LOGPTS(ts, DXFR, LOGL_DEBUG, "RX Message: %d [ %s]\n",
+				rv, osmo_hexdump(ts->hdlc.rx_buf, rv));
+			rv = write(ts->fd, ts->hdlc.rx_buf, bytes_to_write);
+			if (rv < 0)
+				return rv;
+		} else  if (rv < 0 && ts->id == 4) {
+			LOGPTS(ts, DXFR, LOGL_ERROR, "ERR RX: %d %d %d [ %s]\n",
+				rv,oi,cl, osmo_hexdump(buf, len));
+		}
+
+		oi += cl;
+	}
+
+	return len;
+}
+
+static int
+_e1_tx_hdlcfs(struct e1_ts *ts, uint8_t *buf, int len)
+{
+	int rv, oo, cl;
+
+	oo = 0;
+
+	while (oo < len) {
+		/* Pending message ? */
+		if (!ts->hdlc.tx_len) {
+			rv = recv(ts->fd, ts->hdlc.tx_buf, sizeof(ts->hdlc.tx_buf), MSG_TRUNC);
+			if (rv > 0) {
+				if (rv > sizeof(ts->hdlc.tx_buf)) {
+					LOGPTS(ts, DXFR, LOGL_ERROR, "Truncated message: Client tried to "
+						"send %d bytes but our buffer is limited to %lu\n",
+						rv, sizeof(ts->hdlc.tx_buf));
+					rv = sizeof(ts->hdlc.tx_buf);
+				}
+				LOGPTS(ts, DXFR, LOGL_DEBUG, "TX Message: %d [ %s]\n",
+					rv, osmo_hexdump(ts->hdlc.tx_buf, rv));
+				ts->hdlc.tx_len = rv;
+				ts->hdlc.tx_ofs = 0;
+			} else if (rv < 0 && errno != EAGAIN)
+				return rv;
+		}
+
+		/* */
+		rv = osmo_isdnhdlc_encode(&ts->hdlc.tx,
+			&ts->hdlc.tx_buf[ts->hdlc.tx_ofs], ts->hdlc.tx_len - ts->hdlc.tx_ofs, &cl,
+			&buf[oo], len - oo
+		);
+
+		if (rv < 0)
+			LOGPTS(ts, DXFR, LOGL_ERROR, "ERR TX: %d\n", rv);
+
+		if (ts->hdlc.tx_ofs < ts->hdlc.tx_len) {
+			LOGPTS(ts, DXFR, LOGL_DEBUG, "TX chunk %d/%d %d [ %s]\n",
+				ts->hdlc.tx_ofs, ts->hdlc.tx_len, cl, osmo_hexdump(&buf[ts->hdlc.tx_ofs], rv));
+		}
+
+		if (rv > 0)
+			oo += rv;
+
+		ts->hdlc.tx_ofs += cl;
+		if (ts->hdlc.tx_ofs >= ts->hdlc.tx_len) {
+			ts->hdlc.tx_len = 0;
+			ts->hdlc.tx_ofs = 0;
+		}
+	}
+
+	return len;
+}
+
+/* read from a timeslot-FD (direction application -> hardware) */
+static int
+_e1_ts_read(struct e1_ts *ts, uint8_t *buf, size_t len)
+{
+	int l;
+
+	switch (ts->mode) {
+	case E1_TS_MODE_RAW:
+		l = read(ts->fd, buf, len);
+		/* FIXME: handle underflow */
+		break;
+	case E1_TS_MODE_HDLCFCS:
+		l = _e1_tx_hdlcfs(ts, buf, len);
+		break;
+	default:
+		OSMO_ASSERT(0);
+		break;
+	}
+
+	if (l < 0 && errno != EAGAIN) {
+		LOGPTS(ts, DE1D, LOGL_ERROR, "dead socket during read: %s\n",
+			strerror(errno));
+		e1_ts_stop(ts);
+	} else if (l < len) {
+		LOGPTS(ts, DE1D, LOGL_NOTICE, "TS read underflow: We had %zu bytes to read, "
+			"but socket returned only %d\n", len, l);
+	}
+
+	return l;
+}
+
+static void
+_e1_line_mux_out_channelized(struct e1_line *line, uint8_t *buf, int fts)
+{
+	OSMO_ASSERT(line->mode == E1_LINE_MODE_CHANNELIZED);
+
+	/* Scan timeslots */
+	for (int tsn=1; tsn<32; tsn++)
+	{
+		struct e1_ts *ts = &line->ts[tsn];
+		uint8_t buf_ts[fts];
+		int l;
+
+		if (ts->mode == E1_TS_MODE_OFF)
+			continue;
+
+		l = _e1_ts_read(ts, buf_ts, sizeof(buf_ts));
+		if (l <= 0)
+			continue;
+
+		for (int i=0; i<l; i++)
+			buf[tsn+(i*32)] = buf_ts[i];
+	}
+}
+
+static void
+_e1_line_mux_out_superchan(struct e1_line *line, uint8_t *buf, int fts)
+{
+	struct e1_ts *ts = &line->superchan;
+	uint8_t sc_buf[31*fts];
+	int l;
+
+	OSMO_ASSERT(line->mode == E1_LINE_MODE_SUPERCHANNEL);
+
+	if (ts->mode == E1_TS_MODE_OFF)
+		return;
+
+	/* first pull all we need out of the source */
+	l = _e1_ts_read(ts, sc_buf, sizeof(sc_buf));
+	if (l <= 0)
+		return;
+
+	/* then form E1 frames from it, sprinkling in some gaps for TS0 */
+	for (int i = 0; i < fts; i++)
+		memcpy(buf + i*32 + 1, sc_buf + i*31, 31);
+}
+
+/*! generate (multiplex) output data for the specified e1_line
+ *  \param[in] line E1 line for which to genrate output data
+ *  \param[in] buf caller-allocated output buffer for multiplexed data
+ *  \param[in] fts number of E1 frames (32 bytes each) to generate
+ *  \return number of bytes written to buf */
+int
+e1_line_mux_out(struct e1_line *line, uint8_t *buf, int fts)
+{
+	int tsz;
+
+	/* Prepare */
+	tsz = 32 * fts;
+	memset(buf, 0xff, tsz);
+
+	switch (line->mode) {
+	case E1_LINE_MODE_CHANNELIZED:
+		_e1_line_mux_out_channelized(line, buf, fts);
+		break;
+	case E1_LINE_MODE_SUPERCHANNEL:
+		_e1_line_mux_out_superchan(line, buf, fts);
+		break;
+	default:
+		OSMO_ASSERT(0);
+	}
+
+	return tsz;
+}
+
+/* append data to the per-timeslot buffer; flush to socket every time buffer is full */
+static int
+_e1_rx_raw(struct e1_ts *ts, const uint8_t *buf, unsigned int len)
+{
+	unsigned int appended = 0;
+	int rv;
+
+	OSMO_ASSERT(ts->mode == E1_TS_MODE_RAW);
+
+	/* we don't keep a larger set of buffers but simply assume that whenever
+	 * we received one full chunk/buffer size, we are able to push the data
+	 * into the underlying unix domain socket.  Kernel socket buffering should
+	 * be far sufficient in terms of buffering capacity of voice data (which
+	 * is typically consumed reasonably low latency and hence buffer size) */
+
+	while (appended < len) {
+		unsigned int ts_buf_tailroom = ts->raw.rx_buf_size - ts->raw.rx_buf_used;
+		unsigned int chunk_len;
+
+		/* determine size of chunk we can write at this point */
+		chunk_len = len - appended;
+		if (chunk_len > ts_buf_tailroom)
+			chunk_len = ts_buf_tailroom;
+
+		/* actually copy the chunk */
+		memcpy(ts->raw.rx_buf + ts->raw.rx_buf_used, buf + appended, chunk_len);
+		ts->raw.rx_buf_used += chunk_len;
+		appended += chunk_len;
+
+		/* if ts_buf is full: flush + rewind */
+		if (ts->raw.rx_buf_used >= ts->raw.rx_buf_size) {
+			rv = write(ts->fd, ts->raw.rx_buf, ts->raw.rx_buf_size);
+			if (rv < 0)
+				return rv;
+			/* FIXME: count overflows */
+			ts->raw.rx_buf_used = 0;
+		}
+	}
+
+	return appended;
+}
+
+/* write data to a timeslot (hardware -> application direction) */
+static int
+_e1_ts_write(struct e1_ts *ts, const uint8_t *buf, size_t len)
+{
+	int rv;
+
+	switch (ts->mode) {
+	case E1_TS_MODE_RAW:
+		rv = _e1_rx_raw(ts, buf, len);
+		break;
+	case E1_TS_MODE_HDLCFCS:
+		rv = _e1_rx_hdlcfs(ts, buf, len);
+		break;
+	default:
+		OSMO_ASSERT(0);
+		break;
+	}
+
+	if (rv < 0 && errno != EAGAIN) {
+		LOGPTS(ts, DE1D, LOGL_ERROR, "dead socket during write: %s\n",
+			strerror(errno));
+		e1_ts_stop(ts);
+	} else if (rv < len) {
+		LOGPTS(ts, DE1D, LOGL_NOTICE, "TS write overflow: We had %zu bytes to send, "
+			"but write returned only %d\n", len, rv);
+	}
+
+	return rv;
+}
+
+static int
+_e1_line_demux_in_superchan(struct e1_line *line, const uint8_t *buf, int ftr)
+{
+	struct e1_ts *ts = &line->superchan;
+	uint8_t sc_buf[ftr*31];
+
+	OSMO_ASSERT(line->mode == E1_LINE_MODE_SUPERCHANNEL);
+
+	if (ts->mode == E1_TS_MODE_OFF)
+		return 0;
+
+	/* first gather input data from multiple frames*/
+	for (int i = 0; i < ftr; i++)
+		memcpy(sc_buf + (i*31), buf + (i*32) + 1, 31);
+
+	/* then dispatch to appropriate action */
+	_e1_ts_write(ts, sc_buf, ftr*31);
+
+	return 0;
+}
+
+static int
+_e1_line_demux_in_channelized(struct e1_line *line, const uint8_t *buf, int ftr)
+{
+	OSMO_ASSERT(line->mode == E1_LINE_MODE_CHANNELIZED);
+
+	for (int tsn=1; tsn<32; tsn++)
+	{
+		struct e1_ts *ts = &line->ts[tsn];
+		uint8_t buf_ts[ftr];
+
+		if (ts->mode == E1_TS_MODE_OFF)
+			continue;
+
+		for (int i=0; i<ftr; i++)
+			buf_ts[i] = buf[tsn+(i*32)];
+
+		_e1_ts_write(ts, buf_ts, ftr);
+	}
+
+	return 0;
+}
+
+/*! de-multiplex E1 line data to the individual timeslots.
+ *  \param[in] line E1 line on which we operate.
+ *  \param[in] buf buffer containing multiplexed frame-aligned E1 data.
+ *  \param[in] size size of 'buf' in octets; assumed to be multiple of E1 frame size (32).
+ *  \returns 0 on success; negative on error */
+int
+e1_line_demux_in(struct e1_line *line, const uint8_t *buf, int size)
+{
+	int ftr;
+
+	if (size <= 0) {
+		LOGPLI(line, DXFR, LOGL_ERROR, "IN ERROR: %d\n", size);
+		return -1;
+	}
+
+	ftr = size / 32;
+	OSMO_ASSERT(size % 32 == 0);
+
+	switch (line->mode) {
+	case E1_LINE_MODE_CHANNELIZED:
+		return _e1_line_demux_in_channelized(line, buf, ftr);
+	case E1_LINE_MODE_SUPERCHANNEL:
+		return _e1_line_demux_in_superchan(line, buf, ftr);
+	default:
+		OSMO_ASSERT(0);
+	}
+}