Port: restore Windows XP minimal support (c-ares#958)

Windows XP support was removed in 2021, but we've had a recent request for basic Windows XP support. It looks like the needed changes are very minimal these days, the only real requirement is to build without threading support, everything else can be conditionally bypassed. This changeset mostly just disables building the event subsystem if threading is disabled then makes a couple minor build system changes to allow overriding of the `_WIN32_WINNT` macro. Fixes c-ares#956 --------- Signed-off-by: Brad House (@bradh352)
bradh352 · Jan 9, 2025 · 5d7abd1 · 5d7abd1
1 parent eeea199
commit 5d7abd1
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Showing 21 changed files with 131 additions and 64 deletions.
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -274,12 +274,14 @@ ELSEIF (CMAKE_SYSTEM_NAME STREQUAL "FreeBSD")
 ELSEIF (CMAKE_SYSTEM_NAME STREQUAL "QNX")
 	LIST (APPEND SYSFLAGS -D_QNX_SOURCE)
 ELSEIF (WIN32)
-	LIST (APPEND SYSFLAGS -DWIN32_LEAN_AND_MEAN -D_CRT_SECURE_NO_DEPRECATE -D_CRT_NONSTDC_NO_DEPRECATE -D_WIN32_WINNT=0x0602)
+	LIST (APPEND SYSFLAGS -DWIN32_LEAN_AND_MEAN -D_CRT_SECURE_NO_DEPRECATE -D_CRT_NONSTDC_NO_DEPRECATE)
+	IF (NOT CMAKE_C_FLAGS MATCHES ".*-D_WIN32_WINNT=.*")
+		LIST (APPEND SYSFLAGS -D_WIN32_WINNT=0x0602)
+	ENDIF ()
 ENDIF ()
 ADD_DEFINITIONS(${SYSFLAGS})
 
 
-
 # Tell C-Ares about libraries to depend on
 IF (HAVE_LIBRESOLV)
 	LIST (APPEND CARES_DEPENDENT_LIBS resolv)
@@ -426,6 +428,7 @@ CHECK_SYMBOL_EXISTS (getservbyname_r "${CMAKE_EXTRA_INCLUDE_FILES}" HAVE_GETSERV
 CHECK_SYMBOL_EXISTS (gettimeofday    "${CMAKE_EXTRA_INCLUDE_FILES}" HAVE_GETTIMEOFDAY)
 CHECK_SYMBOL_EXISTS (if_indextoname  "${CMAKE_EXTRA_INCLUDE_FILES}" HAVE_IF_INDEXTONAME)
 CHECK_SYMBOL_EXISTS (if_nametoindex  "${CMAKE_EXTRA_INCLUDE_FILES}" HAVE_IF_NAMETOINDEX)
+CHECK_SYMBOL_EXISTS (GetBestRoute2   "${CMAKE_EXTRA_INCLUDE_FILES}" HAVE_GETBESTROUTE2)
 CHECK_SYMBOL_EXISTS (ConvertInterfaceIndexToLuid  "${CMAKE_EXTRA_INCLUDE_FILES}" HAVE_CONVERTINTERFACEINDEXTOLUID)
 CHECK_SYMBOL_EXISTS (ConvertInterfaceLuidToNameA  "${CMAKE_EXTRA_INCLUDE_FILES}" HAVE_CONVERTINTERFACELUIDTONAMEA)
 CHECK_SYMBOL_EXISTS (NotifyIpInterfaceChange      "${CMAKE_EXTRA_INCLUDE_FILES}" HAVE_NOTIFYIPINTERFACECHANGE)

diff --git a/Makefile.m32 b/Makefile.m32
@@ -19,7 +19,9 @@ RANLIB	= $(CROSSPREFIX)ranlib
 #RM	= rm -f
 CP	= cp -afv
 
-CFLAGS	= $(CARES_CFLAG_EXTRAS) -O2 -Wall -I./include -I./src/lib -I./src/lib/include -D_WIN32_WINNT=0x0602
+WIN32_WINNT ?= 0x0602
+
+CFLAGS	= $(CARES_CFLAG_EXTRAS) -O2 -Wall -I./include -I./src/lib -I./src/lib/include -D_WIN32_WINNT=$(WIN32_WINNT)
 CFLAGS	+= -DCARES_STATICLIB
 LDFLAGS	= $(CARES_LDFLAG_EXTRAS) -s
 LIBS	= -lws2_32 -liphlpapi

diff --git a/appveyor.yml b/appveyor.yml
@@ -23,14 +23,14 @@ configuration:
 #     CMAKE_EXTRA_OPTIONS: -DOPENSSL_ROOT_DIR=C:/OpenSSL-Win32
 environment:
   matrix:
-    # MSVC 2022, 32-bit x86 (cmake)
+    # MSVC 2022, 32-bit x86 (cmake, WindowsXP)
     - COMPILER: MSVC
       CONFTOOL: CMAKE
       SYSTEM: CONSOLE
       SKIP_TESTS: no
       MSVC_SETUP_ARG: x86
       MSVC_SETUP_PATH: C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Auxiliary\Build\vcvars32.bat
-      CMAKE_EXTRA_OPTIONS: -GNinja -DCARES_BUILD_TESTS=ON -DGTEST_ROOT=C:\projects\googletest -DCMAKE_MSVC_RUNTIME_LIBRARY=MultiThreadedDebugDLL
+      CMAKE_EXTRA_OPTIONS: -GNinja -DCARES_BUILD_TESTS=ON -DGTEST_ROOT=C:\projects\googletest -DCMAKE_MSVC_RUNTIME_LIBRARY=MultiThreadedDebugDLL -DCARES_THREADS=OFF -DCMAKE_C_FLAGS="-D_WIN32_WINNT=0x0501" -DCMAKE_CXX_FLAGS="-D_WIN32_WINNT=0x0501"
       TOOLSDIR: ./build/bin
       TESTDIR: ./build/bin
       BUILD_GOOGLETEST: yes
@@ -65,23 +65,24 @@ environment:
       MSVC_SETUP_PATH: C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Auxiliary\Build\vcvars32.bat
       BUILD_GOOGLETEST: yes
 
-    # MinGW, 32-bit x86 (makefiles)
+    # MinGW, 32-bit x86 (makefiles, Windows XP)
     - COMPILER: MINGW
       CONFTOOL: MAKE
       SYSTEM: CONSOLE
       SKIP_TESTS: no
       PATH: C:\mingw-w64\i686-8.1.0-posix-dwarf-rt_v6-rev0\mingw32\bin;%PATH%
       BUILD_GOOGLETEST: yes
+      MAKE_FLAGS: WIN32_WINNT=0x0501
 
-    # MinGW, 32-bit x86 (cmake static only)
+    # MinGW, 32-bit x86 (cmake static only, Windows XP)
     - COMPILER: MINGW
       CONFTOOL: CMAKE
       SYSTEM: CONSOLE
       SKIP_TESTS: no
       TOOLSDIR: ./build/bin
       TESTDIR: ./build/bin
       PATH: C:\mingw-w64\i686-8.1.0-posix-dwarf-rt_v6-rev0\mingw32\bin;%PATH%
-      CMAKE_EXTRA_OPTIONS: -DCARES_SHARED=OFF -GNinja -DCARES_BUILD_TESTS=ON -DGTEST_ROOT=C:\projects\googletest
+      CMAKE_EXTRA_OPTIONS: -DCARES_SHARED=OFF -GNinja -DCARES_BUILD_TESTS=ON -DGTEST_ROOT=C:\projects\googletest -DCARES_THREADS=OFF -DCMAKE_C_FLAGS="-D_WIN32_WINNT=0x0501" -DCMAKE_CXX_FLAGS="-D_WIN32_WINNT=0x0501"
       BUILD_GOOGLETEST: yes
 
 # Disabled until AppVeyor updates their Visual Studio with this patch:
@@ -117,7 +118,7 @@ build_script:
   - if "%SYSTEM%" == "CONSOLE" if "%CONFTOOL%" == "CMAKE"     cmake --build build --config Debug
   - if "%SYSTEM%" == "CONSOLE" if "%CONFTOOL%" == "CMAKE"     cmake --install build --config Debug
   - if "%SYSTEM%" == "CONSOLE" if "%CONFTOOL%" == "MAKE"      copy .\include\ares_build.h.dist .\include\ares_build.h
-  - if "%SYSTEM%" == "CONSOLE" if "%CONFTOOL%" == "MAKE"      mingw32-make.exe -f Makefile.m32 demos
+  - if "%SYSTEM%" == "CONSOLE" if "%CONFTOOL%" == "MAKE"      mingw32-make.exe -f Makefile.m32 demos %MAKE_FLAGS%
 
 test_script:
   # We can't use powershell for tests due to treating stderr as an error
@@ -126,8 +127,8 @@ test_script:
   - if "%SYSTEM%" == "CONSOLE" if "%CONFTOOL%" == "NMAKE" if not "%SKIP_TESTS%" == "yes" nmake GTEST_ROOT=C:\projects\googletest /NOLOGO /f .\Makefile.msvc aresfuzz aresfuzzname dnsdump
   - if "%SYSTEM%" == "CONSOLE" if "%CONFTOOL%" == "NMAKE" if not "%SKIP_TESTS%" == "yes" .\msvc\arestest\lib-debug\dnsdump.exe fuzzinput\answer_a fuzzinput\answer_aaaa
   - if "%SYSTEM%" == "CONSOLE" if "%CONFTOOL%" == "MAKE"  if not "%SKIP_TESTS%" == "yes" cd test
-  - if "%SYSTEM%" == "CONSOLE" if "%CONFTOOL%" == "MAKE"  if not "%SKIP_TESTS%" == "yes" mingw32-make.exe GTEST_ROOT=C:\projects\googletest -f Makefile.m32 vtest
-  - if "%SYSTEM%" == "CONSOLE" if "%CONFTOOL%" == "MAKE"  if not "%SKIP_TESTS%" == "yes" mingw32-make.exe GTEST_ROOT=C:\projects\googletest -f Makefile.m32 aresfuzz.exe aresfuzzname.exe dnsdump.exe
+  - if "%SYSTEM%" == "CONSOLE" if "%CONFTOOL%" == "MAKE"  if not "%SKIP_TESTS%" == "yes" mingw32-make.exe GTEST_ROOT=C:\projects\googletest -f Makefile.m32 vtest %MAKE_FLAGS%
+  - if "%SYSTEM%" == "CONSOLE" if "%CONFTOOL%" == "MAKE"  if not "%SKIP_TESTS%" == "yes" mingw32-make.exe GTEST_ROOT=C:\projects\googletest -f Makefile.m32 aresfuzz.exe aresfuzzname.exe dnsdump.exe %MAKE_FLAGS%
   - if "%SYSTEM%" == "CONSOLE" if "%CONFTOOL%" == "MAKE"  if not "%SKIP_TESTS%" == "yes" .\dnsdump.exe fuzzinput\answer_a fuzzinput\answer_aaaa
   - if "%SYSTEM%" == "CONSOLE" if "%CONFTOOL%" == "CMAKE" if not "%SKIP_TESTS%" == "yes" cd %TESTDIR%
   - if "%SYSTEM%" == "CONSOLE" if "%CONFTOOL%" == "CMAKE" if not "%SKIP_TESTS%" == "yes" .\adig.exe www.google.com

diff --git a/configure.ac b/configure.ac
@@ -594,6 +594,7 @@ AC_CHECK_DECL(pipe,            [AC_DEFINE([HAVE_PIPE],              1, [Define t
 AC_CHECK_DECL(pipe2,           [AC_DEFINE([HAVE_PIPE2],             1, [Define to 1 if you have `pipe2`]          )], [], $cares_all_includes)
 AC_CHECK_DECL(kqueue,          [AC_DEFINE([HAVE_KQUEUE],            1, [Define to 1 if you have `kqueue`]         )], [], $cares_all_includes)
 AC_CHECK_DECL(epoll_create1,   [AC_DEFINE([HAVE_EPOLL],             1, [Define to 1 if you have `epoll_{create1,ctl,wait}`])], [], $cares_all_includes)
+AC_CHECK_DECL(GetBestRoute2,   [AC_DEFINE([HAVE_GETBESTROUTE2],     1, [Define to 1 if you have `GetBestRoute2`]  )], [], $cares_all_includes)
 AC_CHECK_DECL(ConvertInterfaceIndexToLuid, [AC_DEFINE([HAVE_CONVERTINTERFACEINDEXTOLUID], 1, [Define to 1 if you have `ConvertInterfaceIndexToLuid`])], [], $cares_all_includes)
 AC_CHECK_DECL(ConvertInterfaceLuidToNameA, [AC_DEFINE([HAVE_CONVERTINTERFACELUIDTONAMEA], 1, [Define to 1 if you have `ConvertInterfaceLuidToNameA`])], [], $cares_all_includes)
 AC_CHECK_DECL(NotifyIpInterfaceChange,     [AC_DEFINE([HAVE_NOTIFYIPINTERFACECHANGE],     1, [Define to 1 if you have `NotifyIpInterfaceChange`]    )], [], $cares_all_includes)

diff --git a/src/lib/ares_config.h.cmake b/src/lib/ares_config.h.cmake
@@ -145,6 +145,9 @@
 /* Define to 1 if you have the `if_nametoindex' function. */
 #cmakedefine HAVE_IF_NAMETOINDEX 1
 
+/* Define to 1 if you have the `GetBestRoute2' function. */
+#cmakedefine HAVE_GETBESTROUTE2 1
+
 /* Define to 1 if you have the `ConvertInterfaceIndexToLuid' function. */
 #cmakedefine HAVE_CONVERTINTERFACEINDEXTOLUID 1
 

diff --git a/src/lib/ares_ipv6.h b/src/lib/ares_ipv6.h
@@ -90,6 +90,16 @@ struct addrinfo {
 #  define NS_INT16SZ 2
 #endif
 
+/* Windows XP Compatibility with later MSVC/Mingw versions */
+#if defined(_WIN32)
+#  if !defined(IF_MAX_STRING_SIZE)
+#    define IF_MAX_STRING_SIZE 256 /* =256 in <ifdef.h> */
+#  endif
+#  if !defined(NDIS_IF_MAX_STRING_SIZE)
+#    define NDIS_IF_MAX_STRING_SIZE IF_MAX_STRING_SIZE   /* =256 in <ifdef.h> */
+#  endif
+#endif
+
 #ifndef IF_NAMESIZE
 #  ifdef IFNAMSIZ
 #    define IF_NAMESIZE IFNAMSIZ

diff --git a/src/lib/ares_sysconfig_win.c b/src/lib/ares_sysconfig_win.c
@@ -176,6 +176,7 @@ static int compareAddresses(const void *arg1, const void *arg2)
   return 0;
 }
 
+#if defined(HAVE_GETBESTROUTE2) && !defined(__WATCOMC__)
 /* There can be multiple routes to "the Internet".  And there can be different
  * DNS servers associated with each of the interfaces that offer those routes.
  * We have to assume that any DNS server can serve any request.  But, some DNS
@@ -213,18 +214,6 @@ static ULONG getBestRouteMetric(IF_LUID * const luid, /* Can't be const :( */
                                 const SOCKADDR_INET * const dest,
                                 const ULONG                 interfaceMetric)
 {
-  /* On this interface, get the best route to that destination. */
-#  if defined(__WATCOMC__)
-  /* OpenWatcom's builtin Windows SDK does not have a definition for
-   * MIB_IPFORWARD_ROW2, and also does not allow the usage of SOCKADDR_INET
-   * as a variable. Let's work around this by returning the worst possible
-   * metric, but only when using the OpenWatcom compiler.
-   * It may be worth investigating using a different version of the Windows
-   * SDK with OpenWatcom in the future, though this may be fixed in OpenWatcom
-   * 2.0.
-   */
-  return (ULONG)-1;
-#  else
   MIB_IPFORWARD_ROW2 row;
   SOCKADDR_INET      ignored;
   if (GetBestRoute2(/* The interface to use.  The index is ignored since we are
@@ -257,8 +246,8 @@ static ULONG getBestRouteMetric(IF_LUID * const luid, /* Can't be const :( */
    * which describes the combination as a "sum".
    */
   return row.Metric + interfaceMetric;
-#  endif /* __WATCOMC__ */
 }
+#endif
 
 /*
  * get_DNS_Windows()
@@ -379,9 +368,21 @@ static ares_bool_t get_DNS_Windows(char **outptr)
           addressesSize = newSize;
         }
 
+#  if defined(HAVE_GETBESTROUTE2) && !defined(__WATCOMC__)
+        /* OpenWatcom's builtin Windows SDK does not have a definition for
+         * MIB_IPFORWARD_ROW2, and also does not allow the usage of SOCKADDR_INET
+         * as a variable. Let's work around this by returning the worst possible
+         * metric, but only when using the OpenWatcom compiler.
+         * It may be worth investigating using a different version of the Windows
+         * SDK with OpenWatcom in the future, though this may be fixed in OpenWatcom
+         * 2.0.
+         */
         addresses[addressesIndex].metric = getBestRouteMetric(
           &ipaaEntry->Luid, (SOCKADDR_INET *)((void *)(namesrvr.sa)),
           ipaaEntry->Ipv4Metric);
+#  else
+        addresses[addressesIndex].metric = (ULONG)-1;
+#  endif
 
         /* Record insertion index to make qsort stable */
         addresses[addressesIndex].orig_idx = addressesIndex;
@@ -423,9 +424,13 @@ static ares_bool_t get_DNS_Windows(char **outptr)
           ll_scope = ipaaEntry->Ipv6IfIndex;
         }
 
+#  if defined(HAVE_GETBESTROUTE2) && !defined(__WATCOMC__)
         addresses[addressesIndex].metric = getBestRouteMetric(
           &ipaaEntry->Luid, (SOCKADDR_INET *)((void *)(namesrvr.sa)),
           ipaaEntry->Ipv6Metric);
+#  else
+        addresses[addressesIndex].metric = (ULONG)-1;
+#  endif
 
         /* Record insertion index to make qsort stable */
         addresses[addressesIndex].orig_idx = addressesIndex;

diff --git a/src/lib/config-win32.h b/src/lib/config-win32.h
@@ -237,8 +237,10 @@
 #  undef HAVE_NETIOAPI_H
 #endif
 
-/* Threading support enabled */
-#define CARES_THREADS 1
+/* Threading support enabled for Vista+ */
+#if !defined(_WIN32_WINNT) || _WIN32_WINNT >= 0x0600
+#  define CARES_THREADS 1
+#endif
 
 /* ---------------------------------------------------------------- */
 /*                       TYPEDEF REPLACEMENTS                       */
@@ -370,6 +372,8 @@
 #  define HAVE_CONVERTINTERFACELUIDTONAMEA 1
 /* Define to 1 if you have the `NotifyIpInterfaceChange' function. */
 #  define HAVE_NOTIFYIPINTERFACECHANGE 1
+/* Define to 1 if you have the `GetBestRoute2` function */
+#  define HAVE_GETBESTROUTE2 1
 #endif
 
 /* ---------------------------------------------------------------- */

diff --git a/src/lib/event/ares_event.h b/src/lib/event/ares_event.h
@@ -159,30 +159,33 @@ ares_status_t ares_event_update(ares_event_t **event, ares_event_thread_t *e,
                                 ares_event_signal_cb_t signal_cb);
 
 
-#ifdef HAVE_PIPE
+#ifdef CARES_THREADS
+#  ifdef HAVE_PIPE
 ares_event_t *ares_pipeevent_create(ares_event_thread_t *e);
-#endif
+#  endif
 
-#ifdef HAVE_POLL
+#  ifdef HAVE_POLL
 extern const ares_event_sys_t ares_evsys_poll;
-#endif
+#  endif
 
-#ifdef HAVE_KQUEUE
+#  ifdef HAVE_KQUEUE
 extern const ares_event_sys_t ares_evsys_kqueue;
-#endif
+#  endif
 
-#ifdef HAVE_EPOLL
+#  ifdef HAVE_EPOLL
 extern const ares_event_sys_t ares_evsys_epoll;
-#endif
+#  endif
 
-#ifdef _WIN32
+#  ifdef _WIN32
 extern const ares_event_sys_t ares_evsys_win32;
-#endif
+#  endif
 
 /* All systems have select(), but not all have a way to wake, so we require
  * pipe() to wake the select() */
-#ifdef HAVE_PIPE
+#  ifdef HAVE_PIPE
 extern const ares_event_sys_t ares_evsys_select;
+#  endif
+
 #endif
 
 #endif
diff --git a/src/lib/event/ares_event_configchg.c b/src/lib/event/ares_event_configchg.c
@@ -26,7 +26,7 @@
 #include "ares_private.h"
 #include "ares_event.h"
 
-#ifdef __ANDROID__
+#if defined(__ANDROID__) && defined(CARES_THREADS)
 
 ares_status_t ares_event_configchg_init(ares_event_configchg_t **configchg,
                                         ares_event_thread_t     *e)
@@ -43,7 +43,7 @@ void ares_event_configchg_destroy(ares_event_configchg_t *configchg)
   (void)configchg;
 }
 
-#elif defined(__linux__)
+#elif defined(__linux__) && defined(CARES_THREADS)
 
 #  include <sys/inotify.h>
 
@@ -174,7 +174,7 @@ ares_status_t ares_event_configchg_init(ares_event_configchg_t **configchg,
   return status;
 }
 
-#elif defined(USE_WINSOCK)
+#elif defined(USE_WINSOCK) && defined(CARES_THREADS)
 
 #  include <winsock2.h>
 #  include <iphlpapi.h>
@@ -379,7 +379,7 @@ ares_status_t ares_event_configchg_init(ares_event_configchg_t **configchg,
   return status;
 }
 
-#elif defined(__APPLE__)
+#elif defined(__APPLE__) && defined(CARES_THREADS)
 
 #  include <sys/types.h>
 #  include <unistd.h>
@@ -531,7 +531,7 @@ ares_status_t ares_event_configchg_init(ares_event_configchg_t **configchg,
   return status;
 }
 
-#elif defined(HAVE_STAT) && !defined(_WIN32)
+#elif defined(HAVE_STAT) && !defined(_WIN32) && defined(CARES_THREADS)
 #  ifdef HAVE_SYS_TYPES_H
 #    include <sys/types.h>
 #  endif
@@ -722,13 +722,16 @@ void ares_event_configchg_destroy(ares_event_configchg_t *configchg)
 ares_status_t ares_event_configchg_init(ares_event_configchg_t **configchg,
                                         ares_event_thread_t     *e)
 {
+  (void)configchg;
+  (void)e;
   /* No ability */
   return ARES_ENOTIMP;
 }
 
 void ares_event_configchg_destroy(ares_event_configchg_t *configchg)
 {
   /* No-op */
+  (void)configchg;
 }
 
 #endif
diff --git a/src/lib/event/ares_event_epoll.c b/src/lib/event/ares_event_epoll.c
@@ -26,15 +26,15 @@
 #include "ares_private.h"
 #include "ares_event.h"
 
+#if defined(HAVE_EPOLL) && defined(CARES_THREADS)
+
 #ifdef HAVE_SYS_EPOLL_H
 #  include <sys/epoll.h>
 #endif
 #ifdef HAVE_FCNTL_H
 #  include <fcntl.h>
 #endif
 
-#ifdef HAVE_EPOLL
-
 typedef struct {
   int epoll_fd;
 } ares_evsys_epoll_t;

diff --git a/src/lib/event/ares_event_kqueue.c b/src/lib/event/ares_event_kqueue.c
@@ -26,6 +26,8 @@
 #include "ares_private.h"
 #include "ares_event.h"
 
+#if defined(HAVE_KQUEUE) && defined(CARES_THREADS)
+
 #ifdef HAVE_SYS_TYPES_H
 #  include <sys/types.h>
 #endif
@@ -39,8 +41,6 @@
 #  include <fcntl.h>
 #endif
 
-#ifdef HAVE_KQUEUE
-
 typedef struct {
   int            kqueue_fd;
   struct kevent *changelist;

diff --git a/src/lib/event/ares_event_poll.c b/src/lib/event/ares_event_poll.c
@@ -25,12 +25,13 @@
  */
 #include "ares_private.h"
 #include "ares_event.h"
+
+#if defined(HAVE_POLL) && defined(CARES_THREADS)
+
 #ifdef HAVE_POLL_H
 #  include <poll.h>
 #endif
 
-#if defined(HAVE_POLL)
-
 static ares_bool_t ares_evsys_poll_init(ares_event_thread_t *e)
 {
   e->ev_signal = ares_pipeevent_create(e);