DNS-SD avahi

Changelog.txt

@@ -1,3 +1,8 @@
+Release 0.5.0 (pending)
+==========================
+
+- Support for DNS-SD publishing and discovery with avahi
+
 Release 0.4.3 (pending)
 ==========================
 

client/Registration.cpp

@@ -4,15 +4,71 @@
 #include "SoapyClient.hpp"
 #include "LogAcceptor.hpp"
 #include "SoapySSDPEndpoint.hpp"
+#include "SoapyMDNSEndpoint.hpp"
 #include "SoapyURLUtils.hpp"
 #include "SoapyRemoteDefs.hpp"
 #include "SoapyRPCPacker.hpp"
 #include "SoapyRPCUnpacker.hpp"
 #include <SoapySDR/Registry.hpp>
 #include <SoapySDR/Logger.hpp>
+#include <memory>
 #include <thread>
 #include <future>
 
+/***********************************************************************
+ * URL discovery
+ **********************************************************************/
+static std::vector<std::string> getServerURLs(const int ipVer, const long timeoutUs)
+{
+    //connect to DNS-SD daemon and maintain a global connection
+    //logic will reconnect if the status has failed for some reason
+    static std::unique_ptr<SoapyMDNSEndpoint> mdnsEndpoint(new SoapyMDNSEndpoint());
+    if (not mdnsEndpoint->status()) mdnsEndpoint.reset(new SoapyMDNSEndpoint());
+
+    //On non-windows platforms the endpoint instance can last the
+    //duration of the process because it can be cleaned up safely.
+    //Windows has issues cleaning up threads and sockets on exit.
+    #ifndef _MSC_VER
+    static
+    #endif //_MSC_VER
+    std::unique_ptr<SoapySSDPEndpoint> ssdpEndpoint(new SoapySSDPEndpoint());
+
+    //get all IPv4 and IPv6 URLs because we will fallback
+    //to the other protocol if the server was found,
+    //but not under the preferred IP protocol version.
+    auto mdnsUrls = std::async(std::launch::async, &SoapyMDNSEndpoint::getServerURLs, mdnsEndpoint.get(), SOAPY_REMOTE_IPVER_UNSPEC, timeoutUs);
+    auto ssdpUrls = std::async(std::launch::async, &SoapySSDPEndpoint::getServerURLs, ssdpEndpoint.get(), SOAPY_REMOTE_IPVER_UNSPEC, timeoutUs);
+
+    //merge the results from the two discovery protocols
+    auto uuidToUrl = ssdpUrls.get();
+    for (const auto &uuidToMap : mdnsUrls.get())
+    {
+        for (const auto &verToUrl : uuidToMap.second)
+        {
+            uuidToUrl[uuidToMap.first][verToUrl.first] = verToUrl.second;
+        }
+    }
+
+    //select the URL according to the ipVersion preference
+    std::vector<std::string> serverUrls;
+    for (const auto &uuidToMap : uuidToUrl)
+    {
+        //prefer version match when found
+        auto itVer = uuidToMap.second.find(ipVer);
+        if (itVer != uuidToMap.second.end())
+        {
+            serverUrls.push_back(itVer->second);
+        }
+
+        //otherwise fall-back to any discovery
+        else if (not uuidToMap.second.empty())
+        {
+            serverUrls.push_back(uuidToMap.second.begin()->second);
+        }
+    }
+    return serverUrls;
+}
+
 /***********************************************************************
  * Args translator for nested keywords
  **********************************************************************/
@@ -64,28 +120,14 @@ static std::vector<SoapySDR::Kwargs> findRemote(const SoapySDR::Kwargs &args)
     //no remote specified, use the discovery protocol
     if (args.count("remote") == 0)
     {
-        //On non-windows platforms the endpoint instance can last the
-        //duration of the process because it can be cleaned up safely.
-        //Windows has issues cleaning up threads and sockets on exit.
-        #ifndef _MSC_VER
-        static
-        #endif //_MSC_VER
-        auto ssdpEndpoint = SoapySSDPEndpoint::getInstance();
-
-        //enable forces new search queries
-        ssdpEndpoint->enablePeriodicSearch(true);
-
-        //wait maximum timeout for replies
-        std::this_thread::sleep_for(std::chrono::microseconds(timeoutUs));
-
         //determine IP version preferences
         int ipVer(4);
         const auto ipVerIt = args.find("remote:ipver");
         if (ipVerIt != args.end()) ipVer = std::stoi(ipVerIt->second);
 
         //spawn futures to connect to each remote
         std::vector<std::future<SoapySDR::KwargsList>> futures;
-        for (const auto &url : SoapySSDPEndpoint::getInstance()->getServerURLs(ipVer))
+        for (const auto &url : getServerURLs(ipVer, timeoutUs))
         {
             auto argsWithURL = args;
             argsWithURL["remote"] = url;
@@ -104,6 +146,7 @@ static std::vector<SoapySDR::Kwargs> findRemote(const SoapySDR::Kwargs &args)
 
     //otherwise connect to a specific url and enumerate
     auto url = SoapyURL(args.at("remote"));
+    SoapySDR::logf(SOAPY_SDR_DEBUG, "SoapyClient querying devices for %s", url.toString().c_str());
 
     //default url parameters when not specified
     if (url.getScheme().empty()) url.setScheme("tcp");

common/CMakeLists.txt

@@ -38,6 +38,24 @@ if (WIN32)
     list(APPEND SoapySDR_LIBRARIES ws2_32)
 endif (WIN32)
 
+#avahi for discovery over dnssd
+if ("${CMAKE_SYSTEM_NAME}" STREQUAL "Linux")
+    list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR})
+    find_package(Avahi)
+endif ()
+
+if (APPLE)
+    list(APPEND COMMON_SOURCES SoapyMDNSEndpointApple.cpp)
+elseif (AVAHI_FOUND)
+    message(STATUS "AVAHI_INCLUDE_DIRS=${AVAHI_INCLUDE_DIRS}")
+    message(STATUS "AVAHI_LIBRARIES=${AVAHI_LIBRARIES}")
+    include_directories(${AVAHI_INCLUDE_DIRS})
+    list(APPEND SoapySDR_LIBRARIES ${AVAHI_LIBRARIES})
+    list(APPEND COMMON_SOURCES SoapyMDNSEndpointAvahi.cpp)
+else ()
+    list(APPEND COMMON_SOURCES SoapyMDNSEndpointNone.cpp)
+endif ()
+
 #create private include header for network compatibility
 include_directories(${CMAKE_CURRENT_BINARY_DIR})
 configure_file(

common/FindAvahi.cmake

@@ -0,0 +1,9 @@
+find_library(AVAHI_LIBRARY-COMMON NAMES avahi-common)
+find_library(AVAHI_LIBRARY-CLIENT NAMES avahi-client)
+find_path(AVAHI_INCLUDE_DIR avahi-client/publish.h)
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(Avahi DEFAULT_MSG AVAHI_LIBRARY-COMMON AVAHI_LIBRARY-CLIENT AVAHI_INCLUDE_DIR)
+if(AVAHI_FOUND)
+    set(AVAHI_LIBRARIES ${AVAHI_LIBRARY-COMMON} ${AVAHI_LIBRARY-CLIENT})
+    set(AVAHI_INCLUDE_DIRS ${AVAHI_INCLUDE_DIR})
+endif()

common/SoapyMDNSEndpoint.hpp

@@ -0,0 +1,49 @@
+// Copyright (c) 2018-2018 Josh Blum
+// SPDX-License-Identifier: BSL-1.0
+
+#pragma once
+#include <string>
+#include <map>
+
+#define SOAPY_REMOTE_DNSSD_NAME "SoapyRemote"
+
+#define SOAPY_REMOTE_DNSSD_TYPE "_soapy._tcp"
+
+struct SoapyMDNSEndpointData;
+
+/*!
+ * The DNS-SD client ties into the system's mDNS daemon.
+ * Used for both server side for publishing,
+ * and the client side for browsing/lookup.
+ */
+class SoapyMDNSEndpoint
+{
+public:
+
+    //! Connect to the daemon
+    SoapyMDNSEndpoint(void);
+
+    //! Disconnect from the daemon
+    ~SoapyMDNSEndpoint(void);
+
+    //! Print information about the client
+    void printInfo(void);
+
+    //! Is the client connected and operational?
+    bool status(void);
+
+    /*!
+     * Allow the endpoint to advertise that its running the RPC service
+     */
+    void registerService(const std::string &uuid, const std::string &service, const int ipVer);
+
+    /*!
+     * Get a list of all active server URLs.
+     * \param ipVer the preferred IP version to discover
+     * \return a mapping of server UUIDs to host URLs
+     */
+    std::map<std::string, std::map<int, std::string>> getServerURLs(const int ipVer, const long timeoutUs);
+
+private:
+    SoapyMDNSEndpointData *_impl;
+};