add osmo-mslookup-client program (#2)

Standalone program using libosmo-mslookup to easily integrate with programs
that want to connect services (SIP, SMS,...) to the current location of a
subscriber. Also useful for manual testing.

For a detailed overview of the D-GSM and mslookup related files, please see the
elaborate comment at the top of mslookup.c (already added in an earlier patch).

Resubmit of 637bbfcd9275f8c47212b29b50110f56ba6397bf after revert in
41fe3625915c456513544b99ba8c057c0f650b3c.

Change-Id: Ie39d30e20461ab10ae3584863d8bfc6b76a12f37

8 files changed, 957 insertions, 1 deletions

diff --git a/.gitignore b/.gitignore
index eec364a..0965935 100644
--- a/.gitignore
+++ b/.gitignore
@@ -36,6 +36,7 @@ src/osmo-hlr
 src/osmo-hlr-db-tool
 src/osmo-euse-demo
 src/gsupclient/gsup-test-client
+src/mslookup/osmo-mslookup-client
 
 tests/atconfig
 tests/testsuite
diff --git a/configure.ac b/configure.ac
index 57aecba..59261e8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -185,6 +185,7 @@ AC_OUTPUT(
 	doc/manuals/Makefile
 	contrib/Makefile
 	contrib/systemd/Makefile
+	contrib/dgsm/Makefile
 	tests/Makefile
 	tests/auc/Makefile
 	tests/auc/gen_ts_55_205_test_sets/Makefile
diff --git a/contrib/Makefile.am b/contrib/Makefile.am
index 3439c97..cfd0b15 100644
--- a/contrib/Makefile.am
+++ b/contrib/Makefile.am
@@ -1 +1,4 @@
-SUBDIRS = systemd
+SUBDIRS = \
+	systemd \
+	dgsm \
+	$(NULL)
diff --git a/contrib/dgsm/Makefile.am b/contrib/dgsm/Makefile.am
new file mode 100644
index 0000000..c759302
--- /dev/null
+++ b/contrib/dgsm/Makefile.am
@@ -0,0 +1,4 @@
+EXTRA_DIST = \
+	osmo-mslookup-pipe.py \
+	osmo-mslookup-socket.py \
+	$(NULL)
diff --git a/contrib/dgsm/osmo-mslookup-pipe.py b/contrib/dgsm/osmo-mslookup-pipe.py
new file mode 100755
index 0000000..b18bf5f
--- /dev/null
+++ b/contrib/dgsm/osmo-mslookup-pipe.py
@@ -0,0 +1,24 @@
+#!/usr/bin/env python3
+# vim: shiftwidth=4 tabstop=4 expandtab
+import subprocess
+import json
+
+def query_mslookup(query_str):
+    result = {'result': 'not-found'}
+    proc = subprocess.Popen(('osmo-mslookup-client', '-f', 'json', query_str),
+		            stdout=subprocess.PIPE)
+    for line in iter(proc.stdout.readline,''):
+        if not line:
+            break
+        response = json.loads(line)
+        if response.get('result') == 'result':
+                result = response
+        print('Response: %r' % response)
+    return result
+
+if __name__ == '__main__':
+    import sys
+    query_str = '1000-5000@sip.voice.12345.msisdn'
+    if len(sys.argv) > 1:
+        query_str = sys.argv[1]
+    print('Final result: %r' % query_mslookup(query_str))
diff --git a/contrib/dgsm/osmo-mslookup-socket.py b/contrib/dgsm/osmo-mslookup-socket.py
new file mode 100755
index 0000000..a26ad9f
--- /dev/null
+++ b/contrib/dgsm/osmo-mslookup-socket.py
@@ -0,0 +1,35 @@
+#!/usr/bin/env python3
+# vim: shiftwidth=4 tabstop=4 expandtab
+import socket
+import time
+
+MSLOOKUP_SOCKET_PATH = '/tmp/mslookup'
+
+def query_mslookup_socket(query_str, socket_path=MSLOOKUP_SOCKET_PATH):
+    mslookup_socket = socket.socket(socket.AF_UNIX, socket.SOCK_SEQPACKET)
+    mslookup_socket.setblocking(True)
+    mslookup_socket.connect(socket_path)
+    result = {'result': 'not-found'}
+    column_names = mslookup_socket.recv(1024).decode('ascii')
+    if not column_names:
+        return result
+    column_names = column_names.split('\t')
+    mslookup_socket.sendall(query_str.encode('ascii'))
+    while True:
+        csv = mslookup_socket.recv(1024).decode('ascii')
+        if not csv:
+            break
+        response = dict(zip(column_names, csv.split('\t')))
+        if response.get('result') == 'result':
+            result = response
+        print('Response: %r' % response)
+    return result
+
+if __name__ == '__main__':
+    import sys
+    print(
+        '\nPlease run separately: osmo-mslookup-client --socket /tmp/mslookup -d\n')
+    query_str = '1000-5000@sip.voice.12345.msisdn'
+    if len(sys.argv) > 1:
+        query_str = sys.argv[1]
+    print('Final result: %r' % query_mslookup_socket(query_str))
diff --git a/src/mslookup/Makefile.am b/src/mslookup/Makefile.am
index 07fb6f4..a720c40 100644
--- a/src/mslookup/Makefile.am
+++ b/src/mslookup/Makefile.am
@@ -26,3 +26,12 @@ libosmo_mslookup_la_LIBADD = \
 	$(LIBOSMOGSM_LIBS) \
 	$(TALLOC_LIBS) \
 	$(NULL)
+
+bin_PROGRAMS = osmo-mslookup-client
+osmo_mslookup_client_SOURCES = osmo-mslookup-client.c
+osmo_mslookup_client_LDADD = \
+	libosmo-mslookup.la \
+	$(LIBOSMOCORE_LIBS) \
+	$(TALLOC_LIBS) \
+	$(NULL)
+osmo_mslookup_client_CFLAGS = $(TALLOC_CFLAGS) $(LIBOSMOCORE_CFLAGS)
diff --git a/src/mslookup/osmo-mslookup-client.c b/src/mslookup/osmo-mslookup-client.c
new file mode 100644
index 0000000..1c0efe9
--- /dev/null
+++ b/src/mslookup/osmo-mslookup-client.c
@@ -0,0 +1,879 @@
+/*! \file osmo-mslookup-client.c
+ * Distributed GSM: find the location of subscribers, for example by multicast DNS,
+ * to obtain HLR, SIP or SMPP server addresses (or arbitrary service names).
+ */
+/*
+ * (C) 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ * (C) 2019 by Neels Hofmeyr <neels@hofmeyr.de>
+ *
+ * All Rights Reserved
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <getopt.h>
+#include <errno.h>
+#include <talloc.h>
+#include <sys/un.h>
+
+#include <osmocom/core/application.h>
+#include <osmocom/core/logging.h>
+#include <osmocom/core/select.h>
+#include <osmocom/core/socket.h>
+#include <osmocom/mslookup/mslookup_client.h>
+#include <osmocom/mslookup/mslookup_client_mdns.h>
+#include <osmocom/mslookup/mdns_sock.h>
+#include <osmocom/mslookup/mdns.h>
+
+#define CSV_HEADERS "query\tresult\tlast\tage\tv4_ip\tv4_port\tv6_ip\tv6_port"
+
+static void print_version(void)
+{
+	printf("osmo-mslookup-client version %s\n", PACKAGE_VERSION);
+	printf("\n"
+	"Copyright (C) 2019 by sysmocom - s.f.m.c. GmbH\n"
+	"Copyright (C) 2019 by Neels Hofmeyr <neels@hofmeyr.de>\n"
+	"This program is free software; you can redistribute it and/or modify\n"
+	"it under the terms of the GNU General Public License as published by\n"
+	"the Free Software Foundation; either version 2 of the License, or\n"
+	"(at your option) any later version.\n"
+	"\n");
+}
+
+static void print_help()
+{
+	print_version();
+	printf(
+"Standalone mslookup client for Distributed GSM\n"
+"\n"
+"Receiving mslookup results means listening for responses on a socket. Often,\n"
+"integration (e.g. FreeSwitch dialplan.py) makes it hard to select() on a socket\n"
+"to read responses, because that interferes with the main program (e.g.\n"
+"FreeSwitch's dialplan.py seems to be integrated with an own select() main loop\n"
+"that interferes with osmo_select_main(), or an smpp.py uses\n"
+"smpplib.client.listen() as main loop, etc.).\n"
+"\n"
+"This program provides a trivial solution, by outsourcing the mslookup main loop\n"
+"to a separate process. Communication is done via cmdline arg and stdout pipe or\n"
+"a (blocking) unix domain socket, results are returned in CSV or JSON format.\n"
+"\n"
+"This can be done one-shot, i.e. exit as soon as the response has been\n"
+"determined, or in daemon form, i.e. continuously listen for requests and return\n"
+"responses.\n"
+"\n"
+"About running a local daemon: it is unintuitive to connect to a socket to solve\n"
+"a problem of reading from a socket -- it seems like just more of the same\n"
+"problem. The reasons why the daemon is in fact useful are:\n"
+"- The osmo-mslookup-client daemon will return only those results matching\n"
+"  requests issued on that socket connection.\n"
+"- A program can simply blockingly recv() from the osmo-mslookup-client socket\n"
+"  instead of needing to run osmo_select_main() so that libosmo-mslookup is able\n"
+"  to asynchronously receive responses from remote servers.\n"
+"- Only one long-lived multicast socket needs to be opened instead of a new\n"
+"  socket for each request.\n"
+"\n"
+"Output is in CSV or json, see --format. The default is tab-separated CSV\n"
+"with these columns:\n"
+CSV_HEADERS "\n"
+"\n"
+"One-shot operation example:\n"
+"$ osmo-mslookup-client 1000-@sip.voice.12345.msisdn -f json\n"
+"{\"query\": \"sip.voice.12345.msisdn\", \"result\": \"result\", \"last\": true, \"age\": 5, \"v4\": [\"1.2.3.7\", \"23\"]}\n"
+"$\n"
+"\n"
+"Daemon operation example:\n"
+"$ osmo-mslookup-client -s /tmp/mslookup -d\n"
+"(and a client program then connects to /tmp/mslookup, find an implementation\n"
+"example below)\n"
+"\n"
+"Integrating with calling programs can be done by:\n"
+"- call osmo-mslookup-client with the query string as argument.\n"
+"  It will open a multicast DNS socket, send out a query and wait for the\n"
+"  matching response. It will print the result on stdout and exit.\n"
+"  This method launches a new process for every mslookup query,\n"
+"  and creates a short-lived multicast listener for each invocation.\n"
+"  This is fine for low activity, but does not scale well.\n"
+"\n"
+"- invoke osmo-mslookup-client --socket /tmp/mslookup -d.\n"
+"  Individual queries can be sent by connecting to that unix domain socket,\n"
+"  blockingly reading the response when it arrives and disconnecting.\n"
+"  This way only one process keeps one multicast listener open.\n"
+"  Callers can connect to this socket without spawning processes.\n"
+"  This is recommended for scale.\n"
+"\n"
+"Python example clients for {CSV,JSON}x{cmdline,socket} can be found here:\n"
+"http://git.osmocom.org/osmo-hlr/tree/contrib/dgsm/osmo-mslookup-pipe.py\n"
+"http://git.osmocom.org/osmo-hlr/tree/contrib/dgsm/osmo-mslookup-socket.py\n"
+"\n"
+"\n"
+"Options:\n"
+"\n"
+"[[delay-][timeout]@]service.number.id\n"
+"	A service query string with optional individual timeout.\n"
+"	The same format is also used on a daemon socket, if any.\n"
+"	The timeout consists of the min-delay and the timeout numbers,\n"
+"	corresponding to the --min-delay and --timeout options, in milliseconds.\n"
+"	These options apply if a query string lacks own numbers.\n"
+"	Examples:\n"
+"		gsup.hlr.1234567.imsi		Use cmdline timeout settings\n"
+"		5000@gsup.hlr.1234567.imsi	Return N results for 5 seconds\n"
+"		1000-5000@sip.voice.123.msisdn	Same, but silent for first second\n"
+"		10000-@smpp.sms.567.msisdn	Return 1 result after 10 seconds\n"
+"\n"
+"--format -f csv (default)\n"
+"	Format result lines in CSV format.\n"
+"--no-csv-headers -H\n"
+"	If the format is 'csv', by default, the first output line prints the\n"
+"	CSV headers used for CSV output format. This option disables these CSV\n"
+"	headers.\n"
+"\n"
+"--format -f json\n"
+"	Format result lines in json instead of semicolon separated, like:\n"
+"	{\"query\": \"sip.voice.12345.msisdn\", \"result\": \"ok\", \"v4\": [\"10.9.8.7\", \"5060\"]}\n"
+"\n"
+"--daemon -d\n"
+"	Keep running after a request has been serviced\n"
+"\n"
+"--mdns-ip -m " OSMO_MSLOOKUP_MDNS_IP4 " -m " OSMO_MSLOOKUP_MDNS_IP6 "\n"
+"--mdns-port -M " OSMO_STRINGIFY_VAL(OSMO_MSLOOKUP_MDNS_PORT) "\n"
+"	Set multicast IP address / port to send mDNS requests and listen for\n"
+"	mDNS reponses\n"
+"--mdns-domain-suffix -D " OSMO_MDNS_DOMAIN_SUFFIX_DEFAULT "\n"
+"	Append this suffix to each mDNS query's domain to avoid colliding with the\n"
+"	top-level domains administrated by IANA.\n"
+"\n"
+"--min-delay -t 1000 (in milliseconds)\n"
+"	Set minimum delay to wait before returning any results.\n"
+"	When this timeout has elapsed, the best current result is returned,\n"
+"	if any is available.\n"
+"	Responses arriving after the min-delay has elapsed which have a younger\n"
+"	age than previous results are returned immediately.\n"
+"	Note: When a response with age of zero comes in, the result is returned\n"
+"	immediately and the request is discarded: non-daemon mode exits, daemon\n"
+"	mode ignores later results.\n"
+"\n"
+"--timeout -T 1000 (in milliseconds)\n"
+"	Set timeout after which to stop listening for responses.\n"
+"	If this is smaller than -t, the value from -t will be used for -T as well.\n"
+"	Note: When a response with age of zero comes in, the result is returned\n"
+"	immediately and the request is discarded: non-daemon mode exits, daemon\n"
+"	mode ignores later results.\n"
+"\n"
+"--socket -s /path/to/unix-domain-socket\n"
+"	Listen to requests from and write responses to a UNIX domain socket.\n"
+"\n"
+"--send -S <query> <age> <ip1> <port1> <ip2> <port2>\n"
+"	Do not query, but send an mslookup result. This is useful only for\n"
+"	testing. Examples:\n"
+"	--send foo.123.msisdn 300 23.42.17.11 1234\n"
+"	--send foo.123.msisdn 300 2323:4242:1717:1111::42 1234\n"
+"	--send foo.123.msisdn 300 23.42.17.11 1234 2323:4242:1717:1111::42 1234\n"
+"\n"
+"--quiet -q\n"
+"	Do not print errors to stderr, do not log to stderr.\n"
+"\n"
+"--help -h\n"
+"	This help\n"
+);
+}
+
+enum result_format {
+	FORMAT_CSV = 0,
+	FORMAT_JSON,
+};
+
+static struct {
+	bool daemon;
+	struct osmo_sockaddr_str mdns_addr;
+	uint32_t min_delay;
+	uint32_t timeout;
+	const char *socket_path;
+	const char *format_str;
+	const char *mdns_domain_suffix;
+	bool csv_headers;
+	bool send;
+	bool quiet;
+} cmdline_opts = {
+	.mdns_addr = { .af=AF_INET, .ip=OSMO_MSLOOKUP_MDNS_IP4, .port=OSMO_MSLOOKUP_MDNS_PORT },
+	.min_delay = 1000,
+	.timeout = 1000,
+	.csv_headers = true,
+	.mdns_domain_suffix = OSMO_MDNS_DOMAIN_SUFFIX_DEFAULT,
+};
+
+#define print_error(fmt, args...) do { \
+		if (!cmdline_opts.quiet) \
+			fprintf(stderr, fmt, ##args); \
+	} while (0)
+
+char g_buf[1024];
+
+long long int parse_int(long long int minval, long long int maxval, const char *arg, int *rc)
+{
+	long long int val;
+	char *endptr;
+	if (rc)
+		*rc = -1;
+	if (!arg)
+		return -1;
+	errno = 0;
+	val = strtoll(arg, &endptr, 10);
+	if (errno || val < minval || val > maxval || *endptr)
+		return -1;
+	if (rc)
+		*rc = 0;
+	return val;
+}
+
+int cb_doing_nothing(struct osmo_fd *fd, unsigned int what)
+{
+	return 0;
+}
+
+/* --send: Just send a response, for manual testing. */
+int do_send(int argc, char ** argv)
+{
+	/* parse args <query> <age> <v4-ip> <v4-port> <v6-ip> <v6-port> */
+#define ARG(NR) ((argc > NR)? argv[NR] : NULL)
+	const char *query_str = ARG(0);
+	const char *age_str = ARG(1);
+	const char *ip_strs[2][2] = {
+		{ ARG(2), ARG(3) },
+		{ ARG(4), ARG(5) },
+	};
+	struct osmo_mslookup_query q = {};
+	struct osmo_mslookup_result r = { .rc = OSMO_MSLOOKUP_RC_RESULT };
+	int i;
+	int rc;
+	void *ctx = talloc_named_const(NULL, 0, __func__);
+	struct osmo_mdns_sock *sock;
+
+	if (!query_str) {
+		print_error("--send needs a query string like foo.123456.imsi\n");
+		return 1;
+	}
+	if (osmo_mslookup_query_init_from_domain_str(&q, query_str)) {
+		print_error("Invalid query string '%s', need a query string like foo.123456.imsi\n",
+			    query_str);
+		return 1;
+	}
+
+	if (!age_str) {
+		print_error("--send needs an age\n");
+		return 1;
+	}
+	r.age = parse_int(0, UINT32_MAX, age_str, &rc);
+	if (rc) {
+		print_error("invalid age\n");
+		return 1;
+	}
+
+	for (i = 0; i < 2; i++) {
+		struct osmo_sockaddr_str addr;
+		uint16_t port;
+		if (!ip_strs[i][0])
+			continue;
+		port = parse_int(1, 65535, ip_strs[i][1] ? : "2342", &rc);
+		if (rc) {
+			print_error("invalid port: %s\n", ip_strs[i][1] ? : "NULL");
+			return 1;
+		}
+		if (osmo_sockaddr_str_from_str(&addr, ip_strs[i][0], port)) {
+			print_error("invalid IP addr: %s\n", ip_strs[i][0]);
+			return 1;
+		}
+		if (addr.af == AF_INET)
+			r.host_v4 = addr;
+		else
+			r.host_v6 = addr;
+	}
+
+	printf("Sending mDNS to " OSMO_SOCKADDR_STR_FMT ": %s\n", OSMO_SOCKADDR_STR_FMT_ARGS(&cmdline_opts.mdns_addr),
+	       osmo_mslookup_result_name_c(ctx, &q, &r));
+
+	rc = 1;
+	sock = osmo_mdns_sock_init(ctx, cmdline_opts.mdns_addr.ip, cmdline_opts.mdns_addr.port,
+				   cb_doing_nothing, NULL, 0);
+	if (!sock) {
+		print_error("unable to open mDNS socket\n");
+		goto exit_cleanup;
+	}
+
+	struct msgb *msg = osmo_mdns_result_encode(ctx, 0, &q, &r, cmdline_opts.mdns_domain_suffix);
+	if (!msg) {
+		print_error("unable to encode mDNS response\n");
+		goto exit_cleanup;
+	}
+
+	if (osmo_mdns_sock_send(sock, msg)) {
+		print_error("unable to send mDNS message\n");
+		goto exit_cleanup;
+	}
+
+	rc = 0;
+exit_cleanup:
+	osmo_mdns_sock_cleanup(sock);
+	talloc_free(ctx);
+	return rc;
+}
+
+static struct {
+	void *ctx;
+	unsigned int requests_handled;
+	struct osmo_fd socket_ofd;
+	struct osmo_mslookup_client *mslookup_client;
+	struct llist_head queries;
+	struct llist_head socket_clients;
+	enum result_format format;
+} globals = {
+	.queries = LLIST_HEAD_INIT(globals.queries),
+	.socket_clients = LLIST_HEAD_INIT(globals.socket_clients),
+};
+
+typedef void (*formatter_t)(char *buf, size_t buflen, const char *query_str, const struct osmo_mslookup_result *r);
+
+void formatter_csv(char *buf, size_t buflen, const char *query_str, const struct osmo_mslookup_result *r)
+{
+	struct osmo_strbuf sb = { .buf=buf, .len=buflen };
+	OSMO_STRBUF_PRINTF(sb, "%s", query_str);
+
+	if (!r)
+		OSMO_STRBUF_PRINTF(sb, "\tERROR\t\t\t\t\t\t");
+	else {
+		OSMO_STRBUF_PRINTF(sb, "\t%s", osmo_mslookup_result_code_name(r->rc));
+		OSMO_STRBUF_PRINTF(sb, "\t%s", r->last ? "last" : "not-last");
+		OSMO_STRBUF_PRINTF(sb, "\t%u", r->age);
+		switch (r->rc) {
+		case OSMO_MSLOOKUP_RC_RESULT:
+			if (osmo_sockaddr_str_is_nonzero(&r->host_v4))
+				OSMO_STRBUF_PRINTF(sb, "\t%s\t%u", r->host_v4.ip, r->host_v4.port);
+			else
+				OSMO_STRBUF_PRINTF(sb, "\t\t");
+			if (osmo_sockaddr_str_is_nonzero(&r->host_v6))
+				OSMO_STRBUF_PRINTF(sb, "\t%s\t%u", r->host_v6.ip, r->host_v6.port);
+			else
+				OSMO_STRBUF_PRINTF(sb, "\t\t");
+			break;
+		default:
+			OSMO_STRBUF_PRINTF(sb, "\t\t\t\t\t");
+			break;
+		}
+	}
+}
+
+void formatter_json(char *buf, size_t buflen, const char *query_str, const struct osmo_mslookup_result *r)
+{
+	struct osmo_strbuf sb = { .buf=buf, .len=buflen };
+	OSMO_STRBUF_PRINTF(sb, "{\"query\": \"%s\"", query_str);
+
+	if (!r)
+		OSMO_STRBUF_PRINTF(sb, ", \"result\": \"ERROR\"");
+	else {
+		OSMO_STRBUF_PRINTF(sb, ", \"result\": \"%s\"", osmo_mslookup_result_code_name(r->rc));
+		OSMO_STRBUF_PRINTF(sb, ", \"last\": %s", r->last ? "true" : "false");
+		OSMO_STRBUF_PRINTF(sb, ", \"age\": %u", r->age);
+		if (r->rc == OSMO_MSLOOKUP_RC_RESULT) {
+			if (osmo_sockaddr_str_is_nonzero(&r->host_v4))
+				OSMO_STRBUF_PRINTF(sb, ", \"v4\": [\"%s\", \"%u\"]", r->host_v4.ip, r->host_v4.port);
+			if (osmo_sockaddr_str_is_nonzero(&r->host_v6))
+				OSMO_STRBUF_PRINTF(sb, ", \"v6\": [\"%s\", \"%u\"]", r->host_v6.ip, r->host_v6.port);
+		}
+	}
+	OSMO_STRBUF_PRINTF(sb, "}");
+}
+
+formatter_t formatters[] = {
+	[FORMAT_CSV] = formatter_csv,
+	[FORMAT_JSON] = formatter_json,
+};
+
+void respond_str_stdout(const char *str) {
+	fprintf(stdout, "%s\n", str);
+	fflush(stdout);
+}
+
+void start_query_str(const char *query_str);
+void start_query_strs(char **query_strs, size_t query_strs_len);
+
+struct socket_client {
+	struct llist_head entry;
+	struct osmo_fd ofd;
+	char query_str[1024];
+};
+
+static void socket_client_close(struct socket_client *c)
+{
+	struct osmo_fd *ofd = &c->ofd;
+
+	close(ofd->fd);
+	ofd->fd = -1;
+	osmo_fd_unregister(ofd);
+
+	llist_del(&c->entry);
+	talloc_free(c);
+}
+
+void socket_client_respond_result(struct socket_client *c, const char *response)
+{
+	write(c->ofd.fd, response, strlen(response));
+}
+
+static int socket_read_cb(struct osmo_fd *ofd)
+{
+	struct socket_client *c = ofd->data;
+	int rc;
+	char rxbuf[1024];
+	char *query_with_timeout;
+	char *query_str;
+	char *at;
+
+	rc = recv(ofd->fd, rxbuf, sizeof(rxbuf), 0);
+	if (rc == 0)
+		goto close;
+
+	if (rc < 0) {
+		if (errno == EAGAIN)
+			return 0;
+		goto close;
+	}
+
+	if (rc >= sizeof(c->query_str))
+		goto close;
+
+	rxbuf[rc] = '\0';
+	query_with_timeout = strtok(rxbuf, "\r\n");
+	at = strchr(query_with_timeout, '@');
+	query_str = at ? at + 1 : query_with_timeout;
+
+	if (c->query_str[0]) {
+		print_error("ERROR: Only one query per client connect is allowed;"
+			    " received '%s' and '%s' on the same connection\n",
+			    c->query_str, query_str);
+		formatters[globals.format](g_buf, sizeof(g_buf), query_str, NULL);
+		socket_client_respond_result(c, g_buf);
+		return 0;
+	}
+
+	OSMO_STRLCPY_ARRAY(c->query_str, query_str);
+	start_query_str(query_with_timeout);
+	printf("query: %s\n", query_with_timeout);
+	return rc;
+
+close:
+	socket_client_close(c);
+	return -1;
+}
+
+static int socket_cb(struct osmo_fd *ofd, unsigned int flags)
+{
+	int rc = 0;
+
+	if (flags & BSC_FD_READ)
+		rc = socket_read_cb(ofd);
+	if (rc < 0)
+		return rc;
+
+	return rc;
+}
+
+int socket_accept(struct osmo_fd *ofd, unsigned int flags)
+{
+	struct socket_client *c;
+	struct sockaddr_un un_addr;
+	socklen_t len;
+	int rc;
+
+	len = sizeof(un_addr);
+	rc = accept(ofd->fd, (struct sockaddr*)&un_addr, &len);
+	if (rc < 0) {
+		print_error("Failed to accept a new connection\n");
+		return -1;
+	}
+
+	c = talloc_zero(globals.ctx, struct socket_client);
+	OSMO_ASSERT(c);
+	c->ofd.fd = rc;
+	c->ofd.when = BSC_FD_READ;
+	c->ofd.cb = socket_cb;
+	c->ofd.data = c;
+
+	if (osmo_fd_register(&c->ofd) != 0) {
+		print_error("Failed to register new connection fd\n");
+		close(c->ofd.fd);
+		c->ofd.fd = -1;
+		talloc_free(c);
+		return -1;
+	}
+
+	llist_add(&c->entry, &globals.socket_clients);
+
+	if (globals.format == FORMAT_CSV && cmdline_opts.csv_headers)
+		write(c->ofd.fd, CSV_HEADERS, strlen(CSV_HEADERS));
+
+	return 0;
+}
+
+int socket_init(const char *sock_path)
+{
+	struct osmo_fd *ofd = &globals.socket_ofd;
+	int rc;
+
+	ofd->fd = osmo_sock_unix_init(SOCK_SEQPACKET, 0, sock_path, OSMO_SOCK_F_BIND);
+	if (ofd->fd < 0) {
+		print_error("Could not create unix socket: %s: %s\n", sock_path, strerror(errno));
+		return -1;
+	}
+
+	ofd->when = BSC_FD_READ;
+	ofd->cb = socket_accept;
+
+	rc = osmo_fd_register(ofd);
+	if (rc < 0) {
+		print_error("Could not register listen fd: %d\n", rc);
+		close(ofd->fd);
+		return rc;
+	}
+	return 0;
+}
+
+void socket_close()
+{
+	struct socket_client *c, *n;
+	llist_for_each_entry_safe(c, n, &globals.socket_clients, entry)
+		socket_client_close(c);
+	if (osmo_fd_is_registered(&globals.socket_ofd)) {
+		close(globals.socket_ofd.fd);
+		globals.socket_ofd.fd = -1;
+		osmo_fd_unregister(&globals.socket_ofd);
+	}
+}
+
+struct query {
+	struct llist_head entry;
+
+	char query_str[128];
+	struct osmo_mslookup_query query;
+	uint32_t handle;
+};
+
+void respond_result(const char *query_str, const struct osmo_mslookup_result *r)
+{
+	struct socket_client *c, *n;
+	formatters[globals.format](g_buf, sizeof(g_buf), query_str, r);
+	respond_str_stdout(g_buf);
+
+	llist_for_each_entry_safe(c, n, &globals.socket_clients, entry) {
+		if (!strcmp(query_str, c->query_str)) {
+			socket_client_respond_result(c, g_buf);
+			if (r->last)
+				socket_client_close(c);
+		}
+	}
+	if (r->last)
+		globals.requests_handled++;
+}
+
+void respond_err(const char *query_str)
+{
+	respond_result(query_str, NULL);
+}
+
+struct query *query_by_handle(uint32_t request_handle)
+{
+	struct query *q;
+	llist_for_each_entry(q, &globals.queries, entry) {
+		if (request_handle == q->handle)
+			return q;
+	}
+	return NULL;
+}
+
+void mslookup_result_cb(struct osmo_mslookup_client *client,
+			uint32_t request_handle,
+			const struct osmo_mslookup_query *query,
+			const struct osmo_mslookup_result *result)
+{
+	struct query *q = query_by_handle(request_handle);
+	if (!q)
+		return;
+	respond_result(q->query_str, result);
+	if (result->last) {
+		llist_del(&q->entry);
+		talloc_free(q);
+	}
+}
+
+void start_query_str(const char *query_str)
+{
+	struct query *q;
+	const char *domain_str = query_str;
+	char *at;
+	struct osmo_mslookup_query_handling h = {
+		.min_wait_milliseconds = cmdline_opts.min_delay,
+		.result_timeout_milliseconds = cmdline_opts.timeout,
+		.result_cb = mslookup_result_cb,
+	};
+
+	at = strchr(query_str, '@');
+	if (at) {
+		int rc;
+		char timeouts[16];
+		char *dash;
+		char *timeout;
+
+		domain_str = at + 1;
+
+		h.min_wait_milliseconds = h.result_timeout_milliseconds = 0;
+
+		if (osmo_print_n(timeouts, sizeof(timeouts), query_str, at - query_str) >= sizeof(timeouts)) {
+			print_error("ERROR: timeouts part too long in query string\n");
+			respond_err(domain_str);
+			return;
+		}
+
+		dash = strchr(timeouts, '-');
+		if (dash) {
+			char min_delay[16];
+			osmo_print_n(min_delay, sizeof(min_delay), timeouts, dash - timeouts);
+			h.min_wait_milliseconds = parse_int(0, UINT32_MAX, min_delay, &rc);
+			if (rc) {
+				print_error("ERROR: invalid min-delay number: %s\n", min_delay);
+				respond_err(domain_str);
+				return;
+			}
+			timeout = dash + 1;
+		} else {
+			timeout = timeouts;
+		}
+		if (*timeout) {
+			h.result_timeout_milliseconds = parse_int(0, UINT32_MAX, timeout, &rc);
+			if (rc) {
+				print_error("ERROR: invalid timeout number: %s\n", timeout);
+				respond_err(domain_str);
+				return;
+			}
+		}
+	}
+
+	if (strlen(domain_str) >= sizeof(q->query_str)) {
+		print_error("ERROR: query string is too long: '%s'\n", domain_str);
+		respond_err(domain_str);
+		return;
+	}
+
+	q = talloc_zero(globals.ctx, struct query);
+	OSMO_ASSERT(q);
+	OSMO_STRLCPY_ARRAY(q->query_str, domain_str);
+
+	if (osmo_mslookup_query_init_from_domain_str(&q->query, q->query_str)) {
+		print_error("ERROR: cannot parse query string: '%s'\n", domain_str);
+		respond_err(domain_str);
+		talloc_free(q);
+		return;
+	}
+
+	q->handle = osmo_mslookup_client_request(globals.mslookup_client, &q->query, &h);
+	if (!q->handle) {
+		print_error("ERROR: cannot send query: '%s'\n", domain_str);
+		respond_err(domain_str);
+		talloc_free(q);
+		return;
+	}
+
+	llist_add(&q->entry, &globals.queries);
+}
+
+void start_query_strs(char **query_strs, size_t query_strs_len)
+{
+	int i;
+	for (i = 0; i < query_strs_len; i++)
+		start_query_str(query_strs[i]);
+}
+
+int main(int argc, char **argv)
+{
+	int rc = EXIT_FAILURE;
+	globals.ctx = talloc_named_const(NULL, 0, "osmo-mslookup-client");
+
+	osmo_init_logging2(globals.ctx, NULL);
+	log_set_print_filename2(osmo_stderr_target, LOG_FILENAME_BASENAME);
+	log_set_print_filename_pos(osmo_stderr_target, LOG_FILENAME_POS_LINE_END);
+	log_set_print_level(osmo_stderr_target, 1);
+	log_set_print_category(osmo_stderr_target, 1);
+	log_set_print_category_hex(osmo_stderr_target, 0);
+	log_set_print_extended_timestamp(osmo_stderr_target, 1);
+	log_set_use_color(osmo_stderr_target, 0);
+
+	while (1) {
+		int c;
+		long long int val;
+		char *endptr;
+		int option_index = 0;
+
+		static struct option long_options[] = {
+			{ "format", 1, 0, 'f' },
+			{ "no-csv-headers", 0, 0, 'H' },
+			{ "daemon", 0, 0, 'd' },
+			{ "mdns-ip", 1, 0, 'm' },
+			{ "mdns-port", 1, 0, 'M' },
+			{ "mdns-domain-suffix", 1, 0, 'D' },
+			{ "timeout", 1, 0, 'T' },
+			{ "min-delay", 1, 0, 't' },
+			{ "socket", 1, 0, 's' },
+			{ "send", 0, 0, 'S' },
+			{ "quiet", 0, 0, 'q' },
+			{ "help", 0, 0, 'h' },
+			{ "version", 0, 0, 'V' },
+			{}
+		};
+
+#define PARSE_INT(TARGET, MINVAL, MAXVAL) do { \
+		int _rc; \
+		TARGET = parse_int(MINVAL, MAXVAL, optarg, &_rc); \
+		if (_rc) { \
+			print_error("Invalid " #TARGET ": %s\n", optarg); \
+			goto program_exit; \
+		} \
+	} while (0)
+
+		c = getopt_long(argc, argv, "f:Hdm:M:D:t:T:s:SqhV", long_options, &option_index);
+
+		if (c == -1)
+			break;
+
+		switch (c) {
+		case 'f':
+			cmdline_opts.format_str = optarg;
+			break;
+		case 'H':
+			cmdline_opts.csv_headers = false;
+			break;
+		case 'd':
+			cmdline_opts.daemon = true;
+			break;
+		case 'm':
+			if (osmo_sockaddr_str_from_str(&cmdline_opts.mdns_addr, optarg, cmdline_opts.mdns_addr.port)
+			    || !osmo_sockaddr_str_is_nonzero(&cmdline_opts.mdns_addr)) {
+				print_error("Invalid mDNS IP address: %s\n", optarg);
+				goto program_exit;
+			}
+			break;
+		case 'M':
+			PARSE_INT(cmdline_opts.mdns_addr.port, 1, 65535);
+			break;
+		case 'D':
+			cmdline_opts.mdns_domain_suffix = optarg;
+			break;
+		case 't':
+			PARSE_INT(cmdline_opts.min_delay, 0, UINT32_MAX);
+			break;
+		case 'T':
+			PARSE_INT(cmdline_opts.timeout, 0, UINT32_MAX);
+			break;
+		case 's':
+			cmdline_opts.socket_path = optarg;
+			break;
+		case 'S':
+			cmdline_opts.send = true;
+			break;
+		case 'q':
+			cmdline_opts.quiet = true;
+			break;
+
+		case 'h':
+			print_help();
+			rc = 0;
+			goto program_exit;
+		case 'V':
+			print_version();
+			rc = 0;
+			goto program_exit;
+
+		default:
+			/* catch unknown options *as well as* missing arguments. */
+			print_error("Error in command line options. Exiting.\n");
+			goto program_exit;
+		}
+	}
+
+	if (cmdline_opts.send) {
+		if (cmdline_opts.daemon || cmdline_opts.format_str || cmdline_opts.socket_path) {
+			print_error("--send option cannot have any listening related args.");
+		}
+		rc = do_send(argc - optind, argv + optind);
+		goto program_exit;
+	}
+
+	if (!cmdline_opts.daemon && !(argc - optind)) {
+		print_help();
+		goto program_exit;
+	}
+
+	if (cmdline_opts.daemon && !cmdline_opts.timeout) {
+		print_error("In daemon mode, --timeout must not be zero.\n");
+		goto program_exit;
+	}
+
+	if (cmdline_opts.quiet)
+		log_target_destroy(osmo_stderr_target);
+
+	if (cmdline_opts.format_str) {
+		if (osmo_str_startswith("json", cmdline_opts.format_str))
+			globals.format = FORMAT_JSON;
+		else if (osmo_str_startswith("csv", cmdline_opts.format_str))
+			globals.format = FORMAT_CSV;
+		else {
+			print_error("Invalid format: %s\n", cmdline_opts.format_str);
+			goto program_exit;
+		}
+	}
+
+	if (globals.format == FORMAT_CSV && cmdline_opts.csv_headers)
+		respond_str_stdout(CSV_HEADERS);
+
+	globals.mslookup_client = osmo_mslookup_client_new(globals.ctx);
+	if (!globals.mslookup_client
+	    || !osmo_mslookup_client_add_mdns(globals.mslookup_client,
+					      cmdline_opts.mdns_addr.ip, cmdline_opts.mdns_addr.port,
+					      -1, cmdline_opts.mdns_domain_suffix)) {
+		print_error("Failed to start mDNS client\n");
+		goto program_exit;
+	}
+
+	if (cmdline_opts.socket_path) {
+		if (socket_init(cmdline_opts.socket_path))
+			goto program_exit;
+	}
+
+	start_query_strs(&argv[optind], argc - optind);
+
+	while (1) {
+		osmo_select_main_ctx(0);
+
+		if (!cmdline_opts.daemon
+		    && globals.requests_handled
+		    && llist_empty(&globals.queries))
+			break;
+	}
+
+	rc = 0;
+program_exit:
+	osmo_mslookup_client_free(globals.mslookup_client);
+	socket_close();
+	log_fini();
+	talloc_free(globals.ctx);
+	return rc;
+}