* resolv/resolv.h (RES_SNGLKUP): Define.

	* resolv/res_init.c (res_setoptions): Recognize single-request option.
	* resolv/res_send.c (send_dg): If we sent two requests at once and
	only get one reply before timeout switch to mode where we send the
	second request only after the first answer has been received.

diff --git a/ChangeLog b/ChangeLog
index 44f1ebc..0646e39 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2009-04-06  Ulrich Drepper  <drepper@redhat.com>
+
+       * resolv/resolv.h (RES_SNGLKUP): Define.
+       * resolv/res_init.c (res_setoptions): Recognize single-request option.
+       * resolv/res_send.c (send_dg): If we sent two requests at once and
+       only get one reply before timeout switch to mode where we send the
+       second request only after the first answer has been received.
+
 2009-04-05  Ulrich Drepper  <drepper@redhat.com>
 
        * sysdeps/x86_64/strlen.S: Optimize by using SSE2 instructions.

diff --git a/resolv/res_init.c b/resolv/res_init.c
index 2bf830c..8841fe9 100644 (file)
--- a/resolv/res_init.c
+++ b/resolv/res_init.c
@@ -540,6 +540,9 @@ res_setoptions(res_state statp, const char *options, const char *source) {
                        statp->options |= RES_NOCHECKNAME;
                 } else if (!strncmp(cp, "edns0", sizeof("edns0") - 1)) {
                        statp->options |= RES_USE_EDNS0;
+                } else if (!strncmp(cp, "single-request",
+                                   sizeof("single-request") - 1)) {
+                       statp->options |= RES_SNGLKUP;
                } else {
                        /* XXX - print a warning here? */
                }

diff --git a/resolv/res_send.c b/resolv/res_send.c
index f75a26e..0490b52 100644 (file)
--- a/resolv/res_send.c
+++ b/resolv/res_send.c
@@ -923,12 +923,12 @@ send_dg(res_state statp,
        struct pollfd pfd[1];
         int ptimeout;
        struct sockaddr_in6 from;
-       int resplen, seconds, n;
+       int resplen, n;
 
        if (EXT(statp).nssocks[ns] == -1) {
                /* only try IPv6 if IPv6 NS and if not failed before */
                if ((EXT(statp).nscount6 > 0) && !statp->ipv6_unavail) {
-                       if (__have_o_nonblock >= 0) {
+                       if (__builtin_expect (__have_o_nonblock >= 0, 1)) {
                                EXT(statp).nssocks[ns] =
                                  socket(PF_INET6, SOCK_DGRAM|SOCK_NONBLOCK,
                                         0);
@@ -939,7 +939,7 @@ send_dg(res_state statp,
                                             && errno == EINVAL ? -1 : 1);
 #endif
                        }
-                       if (__have_o_nonblock < 0)
+                       if (__builtin_expect (__have_o_nonblock < 0, 0))
                                EXT(statp).nssocks[ns] =
                                  socket(PF_INET6, SOCK_DGRAM, 0);
                        if (EXT(statp).nssocks[ns] < 0)
@@ -950,7 +950,7 @@ send_dg(res_state statp,
                            convaddr4to6(nsap);
                }
                if (EXT(statp).nssocks[ns] < 0) {
-                       if (__have_o_nonblock >= 0) {
+                       if (__builtin_expect (__have_o_nonblock >= 0, 1)) {
                                EXT(statp).nssocks[ns]
                                  = socket(PF_INET, SOCK_DGRAM|SOCK_NONBLOCK,
                                           0);
@@ -961,7 +961,7 @@ send_dg(res_state statp,
                                             && errno == EINVAL ? -1 : 1);
 #endif
                        }
-                       if (__have_o_nonblock < 0)
+                       if (__builtin_expect (__have_o_nonblock < 0, 0))
                                EXT(statp).nssocks[ns]
                                  = socket(PF_INET, SOCK_DGRAM, 0);
                }
@@ -989,7 +989,7 @@ send_dg(res_state statp,
                        __res_iclose(statp, false);
                        return (0);
                }
-               if (__have_o_nonblock < 0) {
+               if (__builtin_expect (__have_o_nonblock < 0, 0)) {
                        /* Make socket non-blocking.  */
                        int fl = __fcntl (EXT(statp).nssocks[ns], F_GETFL);
                        if  (fl != -1)
@@ -1003,11 +1003,14 @@ send_dg(res_state statp,
        /*
         * Compute time for the total operation.
         */
-       seconds = (statp->retrans << ns);
+       int seconds = (statp->retrans << ns);
        if (ns > 0)
                seconds /= statp->nscount;
        if (seconds <= 0)
                seconds = 1;
+       bool single_request = ((statp->options) & RES_SNGLKUP) != 0;// XXX
+       int save_gotsomewhere = *gotsomewhere;
+ retry:
        evNowTime(&now);
        evConsTime(&timeout, seconds, 0);
        evAddTime(&finish, &now, &timeout);
@@ -1031,6 +1034,7 @@ send_dg(res_state statp,
                        return (0);
                }
                evSubTime(&timeout, &finish, &now);
+               need_recompute = 0;
        }
         /* Convert struct timespec in milliseconds.  */
        ptimeout = timeout.tv_sec * 1000 + timeout.tv_nsec / 1000000;
@@ -1046,8 +1050,16 @@ send_dg(res_state statp,
                Dprint(statp->options & RES_DEBUG, (stdout, ";; timeout\n"));
                if (resplen > 1 && (recvresp1 || (buf2 != NULL && recvresp2)))
                  {
-                   *resplen2 = 1;
-                   return resplen;
+                   /* There are quite a few broken name servers out
+                      there which don't handle two outstanding
+                      requests from the same source.  There are also
+                      broken firewall settings.  If we time out after
+                      having received one answer switch to the mode
+                      where we send the second request only once we
+                      have received the first answer.  */
+                   single_request = true;
+                   *gotsomewhere = save_gotsomewhere;
+                   goto retry;
                  }
 
                *gotsomewhere = 1;
@@ -1073,7 +1085,7 @@ send_dg(res_state statp,
                        Perror(statp, stderr, "send", errno);
                        goto err_out;
                }
-               if (nwritten != 0 || buf2 == NULL)
+               if (nwritten != 0 || buf2 == NULL || single_request)
                  pfd[0].events = POLLIN;
                else
                  pfd[0].events = POLLIN | POLLOUT;
@@ -1286,8 +1298,11 @@ send_dg(res_state statp,
                else
                        recvresp2 = 1;
                /* Repeat waiting if we have a second answer to arrive.  */
-               if ((recvresp1 & recvresp2) == 0)
+               if ((recvresp1 & recvresp2) == 0) {
+                       if (single_request)
+                               pfd[0].events = POLLOUT;
                        goto wait;
+               }
                /*
                 * All is well, or the error is fatal.  Signal that the
                 * next nameserver ought not be tried.

diff --git a/resolv/resolv.h b/resolv/resolv.h
index a0de320..c6e695d 100644 (file)
--- a/resolv/resolv.h
+++ b/resolv/resolv.h
@@ -215,6 +215,7 @@ struct res_sym {
 #define RES_NOIP6DOTINT        0x00080000      /* Do not use .ip6.int in IPv6
                                           reverse lookup */
 #define RES_USE_EDNS0  0x00100000      /* Use EDNS0.  */
+#define RES_SNGLKUP    0x00200000      /* one outstanding request at a time */
 
 #define RES_DEFAULT    (RES_RECURSE|RES_DEFNAMES|RES_DNSRCH|RES_NOIP6DOTINT)