Add function to write DNS entries

Added function to write DNS entries to specified file
Also, added test case

Change-Id: I64250c7ee3cf7db3e7f8b5cf1669c7b4a7738637
Signed-off-by: Vishwanatha Subbanna <vishwa@linux.vnet.ibm.com>

2 files changed, 103 insertions, 13 deletions

diff --git a/test/Makefile.am b/test/Makefile.am
index 024fa25..5c70fbe 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -2,7 +2,7 @@ AM_CPPFLAGS = -I${top_srcdir} -I${top_builddir}
 
 TESTS = $(check_PROGRAMS)
 
-check_PROGRAMS = test
+check_PROGRAMS = test test_dns_updater
 
 test_SOURCES = \
 	test_util.cpp \
@@ -12,20 +12,30 @@ test_SOURCES = \
 	test_config_parser.cpp \
 	test_vlan_interface.cpp
 
-test_CPPFLAGS = -Igtest $(GTEST_CPPFLAGS) $(AM_CPPFLAGS)
+test_dns_updater_SOURCES = test_dns_updater.cpp
 
-test_CXXFLAGS = $(PTHREAD_CFLAGS) \
-				$(SYSTEMD_CFLAGS) \
-				$(SDBUSPLUS_CFLAGS) \
-				$(PHOSPHOR_LOGGING_CFLAGS) \
-				$(PHOSPHOR_DBUS_INTERFACES_CFLAGS)
+generic_cpp_flags = -Igtest $(GTEST_CPPFLAGS) $(AM_CPPFLAGS)
 
-test_LDFLAGS =	-lgtest_main -lgtest -lstdc++fs \
-				$(OESDK_TESTCASE_FLAGS) \
-				$(SYSTEMD_LIBS) \
-				$(SDBUSPLUS_LIBS) \
-				$(PHOSPHOR_LOGGING_LIBS) \
-				$(PHOSPHOR_DBUS_INTERFACES_LIBS)
+generic_cxx_flags = $(PTHREAD_CFLAGS) \
+					$(SYSTEMD_CFLAGS) \
+					$(SDBUSPLUS_CFLAGS) \
+					$(PHOSPHOR_LOGGING_CFLAGS) \
+					$(PHOSPHOR_DBUS_INTERFACES_CFLAGS)
+
+generic_ld_flags =  -lgtest_main -lgtest -lstdc++fs \
+					$(OESDK_TESTCASE_FLAGS) \
+					$(SYSTEMD_LIBS) \
+					$(SDBUSPLUS_LIBS) \
+					$(PHOSPHOR_LOGGING_LIBS) \
+					$(PHOSPHOR_DBUS_INTERFACES_LIBS)
+
+test_CPPFLAGS = ${generic_cpp_flags}
+test_CXXFLAGS = ${generic_cxx_flags}
+test_LDFLAGS  = ${generic_ld_flags}
+
+test_dns_updater_CPPFLAGS = ${generic_cpp_flags}
+test_dns_updater_CXXFLAGS = ${generic_cxx_flags}
+test_dns_updater_LDFLAGS  = ${generic_ld_flags}
 
 test_LDADD = $(top_builddir)/ethernet_interface.o \
 			$(top_builddir)/network_manager.o \
@@ -40,3 +50,5 @@ test_LDADD = $(top_builddir)/ethernet_interface.o \
 			$(top_builddir)/vlan_interface.o \
 			$(top_builddir)/xyz/openbmc_project/Network/VLAN/Create/phosphor_network_manager-server.o \
 			$(top_builddir)/xyz/openbmc_project/Network/IP/Create/phosphor_network_manager-server.o
+
+test_dns_updater_LDADD = $(top_builddir)/dns_updater.o
diff --git a/test/test_dns_updater.cpp b/test/test_dns_updater.cpp
new file mode 100644
index 0000000..8fb4bcb
--- /dev/null
+++ b/test/test_dns_updater.cpp
@@ -0,0 +1,78 @@
+#include "dns_updater.hpp"
+
+#include <gtest/gtest.h>
+
+#include <fstream>
+#include <experimental/filesystem>
+
+static constexpr auto IN_FILE = "/tmp/netif_state";
+static constexpr auto OUT_FILE = "/tmp/resolv.conf";
+static constexpr auto COMPARE_FILE = "/tmp/resolv_compare.conf";
+static constexpr auto DNS_ENTRY_1 = "DNS=1.2.3.4\n";
+static constexpr auto DNS_ENTRY_2 = "DNS=5.6.7.8\n";
+
+namespace fs = std::experimental::filesystem;
+
+class DnsUpdateTest : public ::testing::Test
+{
+    public:
+        // Gets called as part of each TEST_F construction
+        DnsUpdateTest()
+        {
+            // Create a file containing DNS entries like in netif/state
+            std::ofstream file(IN_FILE);
+            file << DNS_ENTRY_1;
+            file << DNS_ENTRY_2;
+
+            // Create a file to compare the results against
+            std::ofstream compare(COMPARE_FILE);
+            compare << "### Generated by phosphor-networkd ###\n";
+            compare << "nameserver 1.2.3.4\n";
+            compare << "nameserver 5.6.7.8\n";
+        }
+
+        // Gets called as part of each TEST_F destruction
+        ~DnsUpdateTest()
+        {
+            if (fs::exists(IN_FILE))
+            {
+                fs::remove(IN_FILE);
+            }
+            if (fs::exists(OUT_FILE))
+            {
+                fs::remove(OUT_FILE);
+            }
+            if (fs::exists(COMPARE_FILE))
+            {
+                fs::remove(COMPARE_FILE);
+            }
+        }
+};
+
+/** @brief Makes outfile is updated with right contents
+ */
+TEST_F(DnsUpdateTest, validateOutFile)
+{
+    phosphor::network::dns::updater::processDNSEntries(IN_FILE, OUT_FILE);
+
+    // Read files and compare
+    std::ifstream resolv(OUT_FILE);
+    std::ifstream compare(COMPARE_FILE);
+
+    // From actual file
+    std::string resolvEntry{};
+    std::string resolvContent{};
+    while (std::getline(resolv, resolvEntry))
+    {
+        resolvContent += resolvEntry;
+    }
+
+    // From compare file
+    std::string compareEntry{};
+    std::string compareContent{};
+    while (std::getline(compare, compareEntry))
+    {
+        compareContent += compareEntry;
+    }
+    EXPECT_EQ(resolvContent, compareContent);
+}