Problem: no test for ZMQ_BINDTODEVICE

Solution: add test case run with cap_net_admin
Fixes #3397

Makefile.am

@@ -1075,8 +1075,9 @@ EXTRA_DIST = \
 	src/libzmq.vers \
 	src/version.rc.in \
 	tests/CMakeLists.txt \
+        tests/test_pair_tcp_cap_net_admin.cpp \
 	unittests/CMakeLists.txt \
-	tools/curve_keygen.cpp
+        tools/curve_keygen.cpp
 
 MAINTAINERCLEANFILES = \
 	$(srcdir)/aclocal.m4 \

tests/CMakeLists.txt

@@ -79,6 +79,16 @@ if(ZMQ_HAVE_CURVE)
     test_security_curve)
 endif()
 
+find_program(CAPSH_PROGRAM NAMES capsh)
+
+if (CAPSH_PROGRAM)
+    list(APPEND tests
+        test_pair_tcp_cap_net_admin
+        )
+else()
+    message(STATUS "capsh not found, skipping tests that require CAP_NET_ADMIN")
+endif()
+
 if(NOT WIN32)
   list(APPEND tests
     test_ipc_wildcard
@@ -208,7 +218,11 @@ foreach(test ${tests})
   if(WIN32)
     add_test(NAME ${test} WORKING_DIRECTORY ${LIBRARY_OUTPUT_PATH} COMMAND ${test})
   else()
-    add_test(NAME ${test} COMMAND ${test})
+    if (${test} MATCHES "_cap_net_admin")
+      add_test(NAME ${test} COMMAND sh -c "sudo ${CAPSH_PROGRAM} --caps=cap_net_admin+eip -- -c $<TARGET_FILE:${test}>")
+    else()
+      add_test(NAME ${test} COMMAND ${test})
+    endif()
   endif()
   set_tests_properties(${test} PROPERTIES TIMEOUT 10)
   set_tests_properties(${test} PROPERTIES SKIP_RETURN_CODE 77)

tests/test_pair_tcp_cap_net_admin.cpp

@@ -0,0 +1,89 @@
+/*
+    Copyright (c) 2007-2017 Contributors as noted in the AUTHORS file
+
+    This file is part of libzmq, the ZeroMQ core engine in C++.
+
+    libzmq is free software; you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License (LGPL) as published
+    by the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    As a special exception, the Contributors give you permission to link
+    this library with independent modules to produce an executable,
+    regardless of the license terms of these independent modules, and to
+    copy and distribute the resulting executable under terms of your choice,
+    provided that you also meet, for each linked independent module, the
+    terms and conditions of the license of that module. An independent
+    module is a module which is not derived from or based on this library.
+    If you modify this library, you must extend this exception to your
+    version of the library.
+
+    libzmq 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.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "testutil.hpp"
+#include "testutil_unity.hpp"
+
+void setUp ()
+{
+    setup_test_context ();
+}
+
+void tearDown ()
+{
+    teardown_test_context ();
+}
+
+typedef void (*extra_func_t) (void *socket_);
+
+void set_sockopt_bind_to_device (void *socket)
+{
+    const char device[] = "lo";
+    int rc =
+      zmq_setsockopt (socket, ZMQ_BINDTODEVICE, &device, sizeof (device) - 1);
+    assert (rc == 0);
+}
+
+//  TODO this is duplicated from test_pair_tcp
+void test_pair_tcp (extra_func_t extra_func_ = NULL)
+{
+    void *sb = test_context_socket (ZMQ_PAIR);
+
+    if (extra_func_)
+        extra_func_ (sb);
+
+    char my_endpoint[MAX_SOCKET_STRING];
+    bind_loopback_ipv4 (sb, my_endpoint, sizeof my_endpoint);
+
+    void *sc = test_context_socket (ZMQ_PAIR);
+    if (extra_func_)
+        extra_func_ (sc);
+
+    TEST_ASSERT_SUCCESS_ERRNO (zmq_connect (sc, my_endpoint));
+
+    bounce (sb, sc);
+
+    test_context_socket_close (sc);
+    test_context_socket_close (sb);
+}
+
+void test_pair_tcp_bind_to_device ()
+{
+    test_pair_tcp (set_sockopt_bind_to_device);
+}
+
+int main ()
+{
+    setup_test_environment ();
+
+    UNITY_BEGIN ();
+    RUN_TEST (test_pair_tcp_bind_to_device);
+
+    return UNITY_END ();
+}