server: c-ares support

Add the bits we need to be able to use c-ares for DNS operations in the
server.  This handles initialization and making sure the resolver's
sockets and timeouts are considered in the main loop.

4 files changed, 40 insertions, 6 deletions

diff --git a/server/Makefile.in b/server/Makefile.in
index a23b509..666e7ec 100644
--- a/server/Makefile.in
+++ b/server/Makefile.in
@@ -33,7 +33,7 @@ CFLAGS=@CFLAGS@
 ALL_CFLAGS=${CFLAGS} -DSYSCONFDIR=\"${sysconfdir}\" -I${top_srcdir}/h \
 	-I${BUILDTOP}/h -I. ${CPPFLAGS}
 LDFLAGS=@LDFLAGS@
-LIBS=${LIBZEPHYR} @LIBS@ -lcom_err
+LIBS=${LIBZEPHYR} @LIBS@ -lcom_err @ARES_LIBS@
 HESIOD_LIBS=@HESIOD_LIBS@
 
 NMOBJS=	zsrv_err.o access.o acl_files.o bdump.o class.o client.o common.o \
diff --git a/server/global.c b/server/global.c
index 69aea1f..5199f7b 100644
--- a/server/global.c
+++ b/server/global.c
@@ -18,6 +18,9 @@ int srv_socket;				/* dgram socket for clients
 					   and other servers */
 int bdump_socket = -1;			/* brain dump socket fd
 					   (closed most of the time) */
+#ifdef HAVE_ARES
+ares_channel achannel;			/* C-ARES resolver channel */
+#endif
 fd_set interesting;			/* the file descrips we are listening
 					   to right now */
 struct sockaddr_in srv_addr;		/* address of the socket */
diff --git a/server/main.c b/server/main.c
index 4b2f9b7..8e326d9 100644
--- a/server/main.c
+++ b/server/main.c
@@ -93,9 +93,10 @@ int
 main(int argc,
      char **argv)
 {
+    int nselect;		/* #fildes to select on */
     int nfound;			/* #fildes ready on select */
-    fd_set readable;
-    struct timeval tv;
+    fd_set readable, writable;
+    struct timeval tv, *tvp;
     int init_from_dump = 0;
     char *dumpfile;
 #ifdef _POSIX_VERSION
@@ -271,13 +272,24 @@ main(int argc,
 	timer_process();
 
 	readable = interesting;
+	FD_ZERO(&writable);
+	tvp = timer_timeout(&tv);
+#ifdef HAVE_ARES
+	nselect = ares_fds(achannel, &readable, &writable);
+	if (nselect < nfds)
+	    nselect = nfds;
+	tvp = ares_timeout(achannel, tvp, &tv);
+#else
+	nselect = nfds;
+#endif
 	if (msgs_queued()) {
 	    /* when there is input in the queue, we
 	       artificially set up to pick up the input */
 	    nfound = 1;
 	    FD_ZERO(&readable);
+	    FD_ZERO(&writable);
 	} else  {
-	    nfound = select(nfds, &readable, NULL, NULL, timer_timeout(&tv));
+	    nfound = select(nselect, &readable, &writable, NULL, tvp);
 	}
 
 	/* Initialize t_local for other uses */
@@ -291,6 +303,10 @@ main(int argc,
 	    continue;
 	}
 
+#ifdef HAVE_ARES
+	ares_process(achannel, &readable, &writable);
+#endif
+
 	if (nfound == 0) {
 	    /* either we timed out or we were just
 	       polling for input.  Either way we want to continue
@@ -301,8 +317,6 @@ main(int argc,
 		bdump_send();
 	    else if (msgs_queued() || FD_ISSET(srv_socket, &readable))
 		handle_packet();
-	    else
-		syslog(LOG_ERR, "select weird?!?!");
 	}
     }
 }
@@ -384,6 +398,17 @@ do_net_setup(void)
     struct hostent *hp;
     char hostname[NS_MAXDNAME];
     int flags;
+#ifdef HAVE_ARES
+    int status;
+#endif
+
+#ifdef HAVE_ARES
+    status = ares_init(&achannel);
+    if (status != ARES_SUCCESS) {
+	syslog(LOG_ERR, "resolver init failed: %s", ares_strerror(status));
+	return 1;
+    }
+#endif
 
     if (gethostname(hostname, sizeof(hostname))) {
 	syslog(LOG_ERR, "no hostname: %m");
diff --git a/server/zserver.h b/server/zserver.h
index 6ded4a4..822a90c 100644
--- a/server/zserver.h
+++ b/server/zserver.h
@@ -15,6 +15,9 @@
 #include <zephyr/mit-copyright.h>
 
 #include <internal.h>
+#ifdef HAVE_ARES
+#include <ares.h>
+#endif
 
 #include <arpa/inet.h>
 
@@ -423,6 +426,9 @@ extern int srv_socket;			/* dgram sockets for clients
 					   and other servers */
 extern int bdump_socket;		/* brain dump socket
 					   (closed most of the time) */
+#ifdef HAVE_ARES
+extern ares_channel achannel;
+#endif
 
 extern fd_set interesting;		/* the file descrips we are listening
 					 to right now */