libs/nixio: implement optional timeout for getnameinfo() on Linux

diff --git a/libs/nixio/src/address.c b/libs/nixio/src/address.c
index eff05e3..a9759ea 100644 (file)
--- a/libs/nixio/src/address.c
+++ b/libs/nixio/src/address.c
@@ -23,6 +23,15 @@
 #include <string.h>
 
 #ifdef __linux__
+
+#include <signal.h>
+#include <setjmp.h>
+#include <unistd.h>
+
+/* setjmp() / longjmp() stuff */
+static jmp_buf nixio__jump_alarm;
+static void nixio__handle_alarm(int sig) { longjmp(nixio__jump_alarm, 1); }
+
 #include <linux/netdevice.h>
 
 /* struct net_device_stats is buggy on amd64, redefine it */
@@ -271,11 +280,38 @@ static int nixio_getaddrinfo(lua_State *L) {
 }
 
 /**
- * getnameinfo(address, family)
+ * getnameinfo(address, family[, timeout])
  */
 static int nixio_getnameinfo(lua_State *L) {
        const char *ip = luaL_checkstring(L, 1);
        const char *family = luaL_optstring(L, 2, NULL);
+
+#ifdef __linux__
+       struct sigaction sa_new, sa_old;
+       int timeout = luaL_optnumber(L, 3, 0);
+       if (timeout > 0 && timeout < 1000)
+       {
+               sa_new.sa_handler = nixio__handle_alarm;
+               sa_new.sa_flags   = 0;
+               sigemptyset(&sa_new.sa_mask);
+               sigaction(SIGALRM, &sa_new, &sa_old);
+
+               /* user timeout exceeded */
+               if (setjmp(nixio__jump_alarm))
+               {
+                       sigaction(SIGALRM, &sa_old, NULL);
+
+                       lua_pushnil(L);
+                       lua_pushinteger(L, EAI_AGAIN);
+                       lua_pushstring(L, gai_strerror(EAI_AGAIN));
+
+                       return 3;
+               }
+
+               ualarm(timeout * 1000, 0);
+       }
+#endif
+
        char host[NI_MAXHOST];
 
        struct sockaddr_storage saddr;
@@ -297,6 +333,12 @@ static int nixio_getnameinfo(lua_State *L) {
 
        int res = getnameinfo((struct sockaddr *)&saddr, sizeof(saddr),
         host, sizeof(host), NULL, 0, NI_NAMEREQD);
+
+#ifdef __linux__
+       if (timeout > 0 && timeout < 1000)
+               sigaction(SIGALRM, &sa_old, NULL);
+#endif
+
        if (res) {
                lua_pushnil(L);
                lua_pushinteger(L, res);