Invoke gethostbyname once, handle errors better

Instead of invoking gethostbyname once per client, we only need to do it
once at initialization time. Plus: gethostbyname has a non-standard
errno reporting mechanism, handle this better.

diff --git a/blktrace.c b/blktrace.c
index 8e2d47bede291280178280f4c25240f591472413..621e238daea11a322b40bca2d7bd323b363f4b92 100644 (file)
--- a/blktrace.c
+++ b/blktrace.c
@@ -294,6 +294,7 @@ static volatile int dp_entries;
 /*
  * network cmd line params
  */
+static struct sockaddr_in hostname_addr;
 static char hostname[MAXHOSTNAMELEN];
 static int net_port = TRACE_NET_PORT;
 static int net_use_sendfile = 1;
@@ -807,33 +808,55 @@ static int net_get_header(struct cl_conn *nc, struct blktrace_net_hdr *bnh)
        return -1;
 }
 
-static int net_setup_client(void)
+static int net_setup_addr(void)
 {
-       int fd;
-       struct sockaddr_in addr;
+       struct sockaddr_in *addr = &hostname_addr;
 
-       memset(&addr, 0, sizeof(addr));
-       addr.sin_family = AF_INET;
-       addr.sin_port = htons(net_port);
+       memset(addr, 0, sizeof(*addr));
+       addr->sin_family = AF_INET;
+       addr->sin_port = htons(net_port);
 
-       if (inet_aton(hostname, &addr.sin_addr) != 1) {
-               struct hostent *hent = gethostbyname(hostname);
+       if (inet_aton(hostname, &addr->sin_addr) != 1) {
+               struct hostent *hent;
+retry:
+               hent = gethostbyname(hostname);
                if (!hent) {
-                       perror("gethostbyname");
+                       if (h_errno == TRY_AGAIN) {
+                               usleep(100);
+                               goto retry;
+                       } else if (h_errno == NO_RECOVERY) {
+                               fprintf(stderr, "gethostbyname(%s)"
+                                       "non-recoverable error encountered\n",
+                                       hostname);
+                       } else {
+                               /*
+                                * HOST_NOT_FOUND, NO_ADDRESS or NO_DATA
+                                */
+                               fprintf(stderr, "Host %s not found\n",
+                                       hostname);
+                       }
                        return 1;
                }
 
-               memcpy(&addr.sin_addr, hent->h_addr, 4);
+               memcpy(&addr->sin_addr, hent->h_addr, 4);
                strcpy(hostname, hent->h_name);
        }
 
+       return 0;
+}
+
+static int net_setup_client(void)
+{
+       int fd;
+       struct sockaddr_in *addr = &hostname_addr;
+
        fd = my_socket(AF_INET, SOCK_STREAM, 0);
        if (fd < 0) {
                perror("client: socket");
                return -1;
        }
 
-       if (connect(fd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
+       if (connect(fd, (struct sockaddr *)addr, sizeof(*addr)) < 0) {
                if (errno == ECONNREFUSED)
                        fprintf(stderr,
                                "\nclient: Connection to %s refused, "
@@ -2012,6 +2035,9 @@ static int handle_args(int argc, char *argv[])
        if (act_mask_tmp != 0)
                act_mask = act_mask_tmp;
 
+       if (net_mode == Net_client && net_setup_addr())
+               return 1;
+
        /*
         * Set up for appropriate PFD handler based upon output name.
         */