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William Ahern:

Make UDP sockets non-blocking. I've confirmed that at least on Linux 2.4 a
  read event can come back from poll() on a valid SOCK_DGRAM socket but
  recv(2) will still block. This patch doesn't ignore EAGAIN in
  read_udp_packets(), though maybe it should. (This patch was edited by Daniel
  Stenberg and a new configure test was added (imported from curl's configure)
  to properly detect what non-blocking socket approach to use.)
This commit is contained in:
Daniel Stenberg 2005-06-02 11:58:04 +00:00
parent 050bd7dd0b
commit 5470b9aa73
4 changed files with 203 additions and 24 deletions

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@ -4,6 +4,13 @@
- William Ahern:
Make UDP sockets non-blocking. I've confirmed that at least on Linux 2.4 a
read event can come back from poll() on a valid SOCK_DGRAM socket but
recv(2) will still block. This patch doesn't ignore EAGAIN in
read_udp_packets(), though maybe it should. (This patch was edited by Daniel
Stenberg and a new configure test was added (imported from curl's configure)
to properly detect what non-blocking socket approach to use.)
I'm not quite sure how this was happening, but I've been seeing PTR queries
which seem to return empty responses. At least, they were empty when calling
ares_expand_name() on the record. Here's a patch which guarantees to

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@ -1,3 +1,126 @@
dnl Check for how to set a socket to non-blocking state. There seems to exist
dnl four known different ways, with the one used almost everywhere being POSIX
dnl and XPG3, while the other different ways for different systems (old BSD,
dnl Windows and Amiga).
dnl
dnl There are two known platforms (AIX 3.x and SunOS 4.1.x) where the
dnl O_NONBLOCK define is found but does not work. This condition is attempted
dnl to get caught in this script by using an excessive number of #ifdefs...
dnl
AC_DEFUN([CURL_CHECK_NONBLOCKING_SOCKET],
[
AC_MSG_CHECKING([non-blocking sockets style])
AC_TRY_COMPILE([
/* headers for O_NONBLOCK test */
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
],[
/* try to compile O_NONBLOCK */
#if defined(sun) || defined(__sun__) || defined(__SUNPRO_C) || defined(__SUNPRO_CC)
# if defined(__SVR4) || defined(__srv4__)
# define PLATFORM_SOLARIS
# else
# define PLATFORM_SUNOS4
# endif
#endif
#if (defined(_AIX) || defined(__xlC__)) && !defined(_AIX4)
# define PLATFORM_AIX_V3
#endif
#if defined(PLATFORM_SUNOS4) || defined(PLATFORM_AIX_V3) || defined(__BEOS__)
#error "O_NONBLOCK does not work on this platform"
#endif
int socket;
int flags = fcntl(socket, F_SETFL, flags | O_NONBLOCK);
],[
dnl the O_NONBLOCK test was fine
nonblock="O_NONBLOCK"
AC_DEFINE(HAVE_O_NONBLOCK, 1, [use O_NONBLOCK for non-blocking sockets])
],[
dnl the code was bad, try a different program now, test 2
AC_TRY_COMPILE([
/* headers for FIONBIO test */
#include <unistd.h>
#include <stropts.h>
],[
/* FIONBIO source test (old-style unix) */
int socket;
int flags = ioctl(socket, FIONBIO, &flags);
],[
dnl FIONBIO test was good
nonblock="FIONBIO"
AC_DEFINE(HAVE_FIONBIO, 1, [use FIONBIO for non-blocking sockets])
],[
dnl FIONBIO test was also bad
dnl the code was bad, try a different program now, test 3
AC_TRY_COMPILE([
/* headers for ioctlsocket test (cygwin?) */
#include <windows.h>
],[
/* ioctlsocket source code */
int socket;
unsigned long flags = ioctlsocket(socket, FIONBIO, &flags);
],[
dnl ioctlsocket test was good
nonblock="ioctlsocket"
AC_DEFINE(HAVE_IOCTLSOCKET, 1, [use ioctlsocket() for non-blocking sockets])
],[
dnl ioctlsocket didnt compile!, go to test 4
AC_TRY_LINK([
/* headers for IoctlSocket test (Amiga?) */
#include <sys/ioctl.h>
],[
/* IoctlSocket source code */
int socket;
int flags = IoctlSocket(socket, FIONBIO, (long)1);
],[
dnl ioctlsocket test was good
nonblock="IoctlSocket"
AC_DEFINE(HAVE_IOCTLSOCKET_CASE, 1, [use Ioctlsocket() for non-blocking sockets])
],[
dnl Ioctlsocket didnt compile, do test 5!
AC_TRY_COMPILE([
/* headers for SO_NONBLOCK test (BeOS) */
#include <socket.h>
],[
/* SO_NONBLOCK source code */
long b = 1;
int socket;
int flags = setsockopt(socket, SOL_SOCKET, SO_NONBLOCK, &b, sizeof(b));
],[
dnl the SO_NONBLOCK test was good
nonblock="SO_NONBLOCK"
AC_DEFINE(HAVE_SO_NONBLOCK, 1, [use SO_NONBLOCK for non-blocking sockets])
],[
dnl test 5 didnt compile!
nonblock="nada"
AC_DEFINE(HAVE_DISABLED_NONBLOCKING, 1, [disabled non-blocking sockets])
])
dnl end of fifth test
])
dnl end of forth test
])
dnl end of third test
])
dnl end of second test
])
dnl end of non-blocking try-compile test
AC_MSG_RESULT($nonblock)
if test "$nonblock" = "nada"; then
AC_MSG_WARN([non-block sockets disabled])
fi
])
dnl We create a function for detecting which compiler we use and then set as
dnl pendantic compiler options as possible for that particular compiler. The

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@ -466,13 +466,76 @@ void ares__send_query(ares_channel channel, struct query *query, time_t now)
}
}
/*
* nonblock() set the given socket to either blocking or non-blocking mode
* based on the 'nonblock' boolean argument. This function is highly portable.
*/
static int nonblock(ares_socket_t sockfd, /* operate on this */
int nonblock /* TRUE or FALSE */)
{
#undef SETBLOCK
#define SETBLOCK 0
#ifdef HAVE_O_NONBLOCK
/* most recent unix versions */
int flags;
flags = fcntl(sockfd, F_GETFL, 0);
if (TRUE == nonblock)
return fcntl(sockfd, F_SETFL, flags | O_NONBLOCK);
else
return fcntl(sockfd, F_SETFL, flags & (~O_NONBLOCK));
#undef SETBLOCK
#define SETBLOCK 1
#endif
#if defined(HAVE_FIONBIO) && (SETBLOCK == 0)
/* older unix versions */
int flags;
flags = nonblock;
return ioctl(sockfd, FIONBIO, &flags);
#undef SETBLOCK
#define SETBLOCK 2
#endif
#if defined(HAVE_IOCTLSOCKET) && (SETBLOCK == 0)
/* Windows? */
unsigned long flags;
flags = nonblock;
return ioctlsocket(sockfd, FIONBIO, &flags);
#undef SETBLOCK
#define SETBLOCK 3
#endif
#if defined(HAVE_IOCTLSOCKET_CASE) && (SETBLOCK == 0)
/* presumably for Amiga */
return IoctlSocket(sockfd, FIONBIO, (long)nonblock);
#undef SETBLOCK
#define SETBLOCK 4
#endif
#if defined(HAVE_SO_NONBLOCK) && (SETBLOCK == 0)
/* BeOS */
long b = nonblock ? 1 : 0;
return setsockopt(sockfd, SOL_SOCKET, SO_NONBLOCK, &b, sizeof(b));
#undef SETBLOCK
#define SETBLOCK 5
#endif
#ifdef HAVE_DISABLED_NONBLOCKING
return 0; /* returns success */
#undef SETBLOCK
#define SETBLOCK 6
#endif
#if (SETBLOCK == 0)
#error "no non-blocking method was found/used/set"
#endif
}
static int open_tcp_socket(ares_channel channel, struct server_state *server)
{
#if defined(WIN32)
u_long flags;
#else
int flags;
#endif
ares_socket_t s;
struct sockaddr_in sockin;
@ -482,25 +545,7 @@ static int open_tcp_socket(ares_channel channel, struct server_state *server)
return -1;
/* Set the socket non-blocking. */
#if defined(WIN32) || defined(WATT32)
flags = 1;
ioctlsocket(s, FIONBIO, &flags);
#else
flags = fcntl(s, F_GETFL, 0);
if (flags == -1)
{
closesocket(s);
return -1;
}
flags |= O_NONBLOCK;
if (fcntl(s, F_SETFL, flags) == -1)
{
closesocket(s);
return -1;
}
#endif
nonblock(s, TRUE);
/* Connect to the server. */
memset(&sockin, 0, sizeof(sockin));
@ -531,6 +576,9 @@ static int open_udp_socket(ares_channel channel, struct server_state *server)
if (s == ARES_SOCKET_BAD)
return -1;
/* Set the socket non-blocking. */
nonblock(s, TRUE);
/* Connect to the server. */
memset(&sockin, 0, sizeof(sockin));
sockin.sin_family = AF_INET;

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@ -328,5 +328,6 @@ AC_CHECK_SIZEOF(struct in_addr, ,
AC_CHECK_FUNCS([bitncmp if_indextoname])
CURL_CHECK_NONBLOCKING_SOCKET
AC_OUTPUT(Makefile)