ip_utils: add getHostname()

Add method to retreive the hostname,
to fill the default device name.

Change-Id: I5aafe8d0413caa13c4fdf720f6f3ce8b0577d238

src/ip_utils.cpp

@@ -28,14 +28,33 @@
 
 #include <sys/types.h>
 #include <unistd.h>
+#include <limits.h>
 
 #ifdef _WIN32
 #define InetPtonA inet_pton
 WINSOCK_API_LINKAGE INT WSAAPI InetPtonA(INT Family, LPCSTR pStringBuf, PVOID pAddr);
 #endif
 
+#ifndef HOST_NAME_MAX
+#ifdef MAX_COMPUTERNAME_LENGTH
+#define HOST_NAME_MAX MAX_COMPUTERNAME_LENGTH
+#else
+// Max 255 chars as per RFC 1035
+#define HOST_NAME_MAX 255
+#endif
+#endif
+
 namespace ring {
 
+std::string
+ip_utils::getHostname()
+{
+    char hostname[HOST_NAME_MAX];
+    if (gethostname(hostname, HOST_NAME_MAX))
+        return {};
+    return hostname;
+}
+
 std::vector<IpAddr>
 ip_utils::getAddrList(const std::string &name, pj_uint16_t family)
 {

src/ip_utils.h

@@ -235,6 +235,8 @@ namespace ip_utils {
 
 static const char *const DEFAULT_INTERFACE = "default";
 
+std::string getHostname();
+
 /**
  * Return the generic "any host" IP address of the specified family.
  * If family is unspecified, default to pj_AF_INET6() (IPv6).