convert select() => poll(), saves a runtime malloc+free per retry

feedback deraadt@ drahn@; ok deraadt@

1 files changed, 16 insertions, 23 deletions

diff --git a/src/lib/libc/net/res_send.c b/src/lib/libc/net/res_send.c
index f7631350bc..187210cbd8 100644
--- a/src/lib/libc/net/res_send.c
+++ b/src/lib/libc/net/res_send.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: res_send.c,v 1.19 2005/08/06 20:30:04 espie Exp $     */
+/*      $OpenBSD: res_send.c,v 1.20 2008/04/18 21:36:32 djm Exp $       */
 
 /*
  * ++Copyright++ 1985, 1989, 1993
@@ -75,10 +75,11 @@
 #include <arpa/nameser.h>
 #include <arpa/inet.h>
 
-#include <stdio.h>
-#include <netdb.h>
 #include <errno.h>
+#include <netdb.h>
+#include <poll.h>
 #include <resolv.h>
+#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
@@ -466,7 +467,7 @@ res_send(const u_char *buf, int buflen, u_char *ans, int anssiz)
                         /*
                          * Receive length & response
                          */
-read_len:
+ read_len:
                         cp = ans;
                         len = INT16SZ;
                         while ((n = read(s, (char *)cp, (int)len)) > 0) {
@@ -553,8 +554,8 @@ read_len:
                         /*
                          * Use datagrams.
                          */
-                        struct timeval timeout;
-                        fd_set *dsmaskp;
+                        struct pollfd pfd;
+                        int timeout;
                         struct sockaddr_storage from;
                         socklen_t fromlen;
 
@@ -594,7 +595,7 @@ read_len:
                          * ICMP port unreachable message to be returned.
                          * If our datagram socket is "connected" to the
                          * server, we get an ECONNREFUSED error on the next
-                         * socket operation, and select returns if the
+                         * socket operation, and poll returns if the
                          * error message is received.  We can thus detect
                          * the absence of a nameserver without timing out.
                          * If we have sent queries to at least two servers,
@@ -676,27 +677,19 @@ read_len:
                         /*
                          * Wait for reply
                          */
-                        timeout.tv_sec = (_resp->retrans << try);
+                        timeout = 1000 * (_resp->retrans << try);
                         if (try > 0)
-                                timeout.tv_sec /= _resp->nscount;
-                        if ((long) timeout.tv_sec <= 0)
-                                timeout.tv_sec = 1;
-                        timeout.tv_usec = 0;
+                                timeout /= _resp->nscount;
+                        if (timeout < 1000)
+                                timeout = 1000;
     wait:
-                        dsmaskp = (fd_set *)calloc(howmany(s+1, NFDBITS),
-                                                   sizeof(fd_mask));
-                        if (dsmaskp == NULL) {
-                                res_close();
-                                goto next_ns;
-                        }
-                        FD_SET(s, dsmaskp);
-                        n = select(s+1, dsmaskp, (fd_set *)NULL,
-                                   (fd_set *)NULL, &timeout);
-                        free(dsmaskp);
+                        pfd.fd = s;
+                        pfd.events = POLLIN;
+                        n = poll(&pfd, 1, timeout);
                         if (n < 0) {
                                 if (errno == EINTR)
                                         goto wait;
-                                Perror(stderr, "select", errno);
+                                Perror(stderr, "poll", errno);
                                 res_close();
                                 goto next_ns;
                         }