fix(inputs/pcap): look up iface by name unless it is an address

src/inputs/pcap/CMakeLists.txt

@@ -22,6 +22,7 @@ set(VISOR_STATIC_PLUGINS ${VISOR_STATIC_PLUGINS} Visor::Input::Pcap PARENT_SCOPE
 
 ## TEST SUITE
 add_executable(unit-tests-input-pcap
+        tests/test_iface.cpp
         tests/test_mock_traffic.cpp
         tests/test_parse_pcap.cpp)
 

src/inputs/pcap/PcapInputStream.cpp

@@ -155,8 +155,12 @@ void PcapInputStream::start()
             }
             config_set("iface", TARGET);
         }
-        interfaceIP4 = TARGET;
-        interfaceIP6 = TARGET;
+        // iface is an interface name or an address; parsing a name as an address throws
+        if (pcpp::IPv4Address::isValidIPv4Address(TARGET)) {
+            interfaceIP4 = pcpp::IPv4Address(TARGET);
+        } else if (pcpp::IPv6Address::isValidIPv6Address(TARGET)) {
+            interfaceIP6 = pcpp::IPv6Address(TARGET);
+        }
     }
     std::string ifNameList = _get_interface_list();
 

src/inputs/pcap/tests/test_iface.cpp

@@ -0,0 +1,39 @@
+#include "PcapInputStream.h"
+#include <catch2/catch_test_macros.hpp>
+#include <catch2/matchers/catch_matchers_string.hpp>
+
+using namespace visor::input::pcap;
+using Catch::Matchers::StartsWith;
+
+// iface may be an interface name or an address, and only an address may be parsed as one. The addresses
+// are reserved for documentation (RFC 5737, RFC 3849), so the lookup fails before any capture opens.
+TEST_CASE("iface accepts a name, an IPv4 address or an IPv6 address", "[pcap][iface]")
+{
+    SECTION("name")
+    {
+        PcapInputStream stream{"pcap-test"};
+        stream.config_set("iface", "pktvisor-test0");
+        CHECK_THROWS_WITH(stream.start(), StartsWith("Couldn't find interface by provided name: \"pktvisor-test0\""));
+    }
+
+    SECTION("IPv4 address")
+    {
+        PcapInputStream stream{"pcap-test"};
+        stream.config_set("iface", "192.0.2.1");
+        CHECK_THROWS_WITH(stream.start(), "Couldn't find interface by provided IP: 192.0.2.1");
+    }
+
+    SECTION("IPv6 address")
+    {
+        PcapInputStream stream{"pcap-test"};
+        stream.config_set("iface", "2001:db8::1");
+        CHECK_THROWS_WITH(stream.start(), "Couldn't find interface by provided IP: 2001:db8::1");
+    }
+
+    SECTION("the zero address is looked up as a name")
+    {
+        PcapInputStream stream{"pcap-test"};
+        stream.config_set("iface", "0.0.0.0");
+        CHECK_THROWS_WITH(stream.start(), StartsWith("Couldn't find interface by provided name: \"0.0.0.0\""));
+    }
+}