Initial support for figuring out inbound interface for inetd connections

This patch adds initial support (only SOCK_STREAM verified!) for
figuring out the inbound interface for inetd service connections.

The intention is to use this later on for a very simple tcpwrappers
replacement, e.g: `deny telnet eth0 eth3`

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

inetd.h

@@ -26,6 +26,9 @@
 
 #include "libuev/uev.h"
 
+int  inetd_dgram_peek  (int sd, char *ifname);
+int  inetd_stream_peek (int sd, char *ifname);
+
 int  inetd_respawn (pid_t pid);
 void inetd_runlevel(uev_ctx_t *ctx, int runlevel);