Added Bonjour DNS SD implementation (macOS).

Signed-off-by: Matej Kenda <[email protected]>

CMakeLists.txt

@@ -253,14 +253,29 @@ if(WITH_NETWORK_BACKEND)
 
 	find_library(AVAHI_CLIENT_LIBRARIES avahi-client)
 	find_library(AVAHI_COMMON_LIBRARIES avahi-common)
-	if(AVAHI_CLIENT_LIBRARIES AND AVAHI_COMMON_LIBRARIES)
-		message(STATUS "Building with Avahi, a zero-configuration networking (zeroconf) implementation")
-		set(HAVE_AVAHI ON)
+	if(${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
+		find_library(CORE_SERVICES CoreServices)
+
+		message(STATUS "Building with CFNetServices, an Apple DNS SD implementation")
+		set(HAVE_DNS_SD ON)
+
+		list(APPEND LIBIIO_CFILES dns_sd_bonjour.c)
+		list(APPEND LIBS_TO_LINK ${CORE_SERVICES} )
+
+	elseif(AVAHI_CLIENT_LIBRARIES AND AVAHI_COMMON_LIBRARIES)
+		message(STATUS "Building with Avahi, a DNS SD implementation")
+		set(HAVE_DNS_SD ON)
+
+		list(APPEND LIBIIO_CFILES dns_sd_avahi.c)
 		set(AVAHI_LIBRARIES ${AVAHI_CLIENT_LIBRARIES} ${AVAHI_COMMON_LIBRARIES})
-		set(LIBS_TO_LINK ${LIBS_TO_LINK} ${AVAHI_LIBRARIES})
+		list(APPEND LIBS_TO_LINK ${AVAHI_LIBRARIES})
 		set(AVAHI_SERVICE_INSTALL_DIR /etc/avahi/services/ CACHE PATH "default install path for Avahi service files")
 	else()
-		message(STATUS "Building without Avahi (zeroconf) support")
+		message(STATUS "Building without DNS-SD (Zeroconf) support")
+	endif()
+
+	if (HAVE_DNS_SD)
+		add_definitions(-DHAVE_DNS_SD=1)
 	endif()
 
 	set(NEED_THREADS 1)

dns_sd_bonjour.c

@@ -0,0 +1,167 @@
+/*
+ * libiio - Library for interfacing industrial I/O (IIO) devices
+ *
+ * Copyright (C) 2020 Matej Kenda.
+ * Author: Matej Kenda <matejken<at>gmail.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * */
+
+#include <errno.h>
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+#include <CFNetwork/CFNetwork.h>
+
+#include "debug.h"
+
+/*
+ Implementation for DNS SD discovery for macOS using CFNetServices.
+*/
+
+struct cfnet_discovery_data {
+	bool	have_v4;
+	bool	have_v6;
+	char 	address_v4[80];
+	char 	address_v6[80];
+	int16_t port;
+};
+
+static void __cfnet_browser_cb (
+	CFNetServiceBrowserRef	browser,
+	CFOptionFlags 			flags,
+	CFTypeRef 				domainOrService,
+	CFStreamError* 			error,
+	void* 					info)
+{
+	CFStreamError anError;
+
+	if ((flags & kCFNetServiceFlagIsDomain) != 0) {
+		ERROR("DNS SD: FATAL. Callback called for domain, not service.\n");
+		goto stop_browsing;
+	}
+
+	struct cfnet_discovery_data *dd = (struct cfnet_discovery_data *)info;
+	if (dd == NULL) {
+		ERROR("DNS SD: Missing info structure. Stop browsing.\n");
+		goto stop_browsing;
+	}
+
+	if (dd->have_v4 || dd->have_v6) {
+		// Already resolved one IIO service. Stop.
+		DEBUG("DNS SD: first service already resolved. Skip.\n");
+		goto stop_browsing;
+	}
+
+	const CFNetServiceRef netService = (CFNetServiceRef)domainOrService;
+	if (netService == NULL) {
+		ERROR("DNS SD: Net service is null.\n");
+		goto stop_browsing;
+	}
+
+	if (!CFNetServiceResolveWithTimeout(netService, 10.0, &anError)) {
+		ERROR("DNS SD: Resolve error: %ld.%d\n", anError.domain, anError.error);
+		goto stop_browsing;
+	}
+
+	dd->port = CFNetServiceGetPortNumber(netService);
+
+	CFArrayRef addrArr = CFNetServiceGetAddressing(netService);
+	if (addrArr == NULL) {
+		ERROR("DNS SD: No valid addresses for service.\n");
+		goto stop_browsing;
+	}
+
+	for (CFIndex i = 0; i < CFArrayGetCount(addrArr); i++) {
+		struct sockaddr_in *sa = (struct sockaddr_in *)
+		CFDataGetBytePtr(CFArrayGetValueAtIndex(addrArr, i));
+		switch(sa->sin_family) {
+			case AF_INET:
+				if (inet_ntop(sa->sin_family, &sa->sin_addr,
+							  dd->address_v4, sizeof(dd->address_v4))) {
+					dd->have_v4 = TRUE;
+				}
+			case AF_INET6:
+				if (inet_ntop(sa->sin_family, &sa->sin_addr,
+							  dd->address_v6, sizeof(dd->address_v6))) {
+					dd->have_v6 = TRUE;
+				}
+		}
+	}
+
+	if ((flags & kCFNetServiceFlagMoreComing) == 0) {
+		DEBUG("DNS SD: No more entries coming.\n");
+		goto stop_browsing;
+	}
+
+	return;
+
+stop_browsing:
+
+	CFNetServiceBrowserStopSearch(browser, &anError);
+}
+
+int discover_host(char *addr_str, size_t addr_len, uint16_t *port)
+{
+	int ret = 0;
+
+	struct cfnet_discovery_data ddata = { FALSE, FALSE };
+	CFNetServiceClientContext clientContext = { 0, &ddata, NULL, NULL, NULL };
+	CFStreamError error;
+	Boolean result;
+
+	CFStringRef type = CFSTR("_iio._tcp.");
+	CFStringRef domain = CFSTR("");
+
+	DEBUG("DNS SD: Resolving hostname.");
+
+	CFNetServiceBrowserRef gServiceBrowserRef = CFNetServiceBrowserCreate(
+		kCFAllocatorDefault, __cfnet_browser_cb, &clientContext);
+
+	if (gServiceBrowserRef == NULL) {
+		ERROR("DNS SD: Failed to create service browser.\n");
+		ret = ENOMEM;
+		goto exit;
+	}
+	result = CFNetServiceBrowserSearchForServices(
+		gServiceBrowserRef, domain, type, &error);
+
+	if (result == false) {
+		ERROR("DNS SD: CFNetServiceBrowserSearchForServices failed (domain = %ld, error = %d)\n",
+			(long)error.domain, error.error);
+		ret = ENXIO;
+		goto free_browser;
+	}
+
+	// Resolved address and port. ipv4 has precedence over ipv6.
+	*port = ddata.port;
+	if (ddata.have_v4) {
+		strncpy(addr_str, ddata.address_v4, addr_len);
+	}
+	else if (ddata.have_v6) {
+		strncpy(addr_str, ddata.address_v6, addr_len);
+	}
+	else {
+		ERROR("DNS SD: IIO service not found.\n");
+		ret = ENXIO;
+	}
+
+free_browser:
+
+	CFRelease(gServiceBrowserRef);
+	gServiceBrowserRef = NULL;
+
+exit:
+	return ret;
+}
+