Add methods to get the hostname and network interfaces.

src/cscore_cpp.cpp

@@ -7,6 +7,13 @@
 
 #include "cscore_cpp.h"
 
+#if defined(__linux__)
+#include <arpa/inet.h>
+#include <ifaddrs.h>
+#include <sys/types.h>
+#include <unistd.h>
+#endif
+
 #include "llvm/SmallString.h"
 
 #include "Notifier.h"
@@ -511,4 +518,39 @@ llvm::ArrayRef<CS_Sink> EnumerateSinkHandles(
   return Sinks::GetInstance().GetAll(vec);
 }
 
+std::string GetHostname() {
+#ifdef __linux__
+  char name[256];
+  if (::gethostname(name, sizeof(name)) != 0) return "";
+  name[255] = '\0';  // Per POSIX, may not be null terminated if too long
+  return name;
+#else
+  return "";  // TODO
+#endif
+}
+
+std::vector<std::string> GetNetworkInterfaces() {
+#ifdef __linux__
+  struct ifaddrs* ifa;
+  if (::getifaddrs(&ifa) != 0) return std::vector<std::string>{};
+
+  std::vector<std::string> rv;
+  char buf[256];
+  for (struct ifaddrs* i = ifa; i; i = i->ifa_next) {
+    if (!i->ifa_addr) continue;  // no address
+    if (i->ifa_addr->sa_family != AF_INET) continue;  // only return IPv4
+    struct sockaddr_in* addr_in = reinterpret_cast<sockaddr_in*>(i->ifa_addr);
+    const char* addr =
+        ::inet_ntop(addr_in->sin_family, &addr_in->sin_addr, buf, sizeof(buf));
+    if (!addr) continue;  // error converting address
+    rv.emplace_back(addr);
+  }
+
+  ::freeifaddrs(ifa);
+  return rv;
+#else
+  return std::vector<std::string>{};  // TODO
+#endif
+}
+
 }  // namespace cs