z/OS: port (#390)

Port c-ares to z/OS.

Fix By: Dhrumil Rana (@dhrumilrana)

CMakeLists.txt

@@ -138,7 +138,7 @@ return 0;
 	MACOS_V1012)
 ENDIF ()
 
-IF ((IOS OR APPLE) AND HAVE_LIBRESOLV)
+IF ((IOS OR APPLE OR ZOS) AND HAVE_LIBRESOLV)
 	SET (CARES_USE_LIBRESOLV 1)
 ENDIF()
 

configure.ac

@@ -386,6 +386,15 @@ AS_IF([test "x$host_vendor" = "xapple"], [
   ])
 ])
 
+dnl resolv lib for z/OS
+AS_IF([test "x$host_vendor" = "xibm" -a "x$host_os" = "xopenedition" ], [
+  AC_SEARCH_LIBS([res_init], [resolv], [
+    AC_DEFINE([CARES_USE_LIBRESOLV], [1], [Use resolver library to configure cares])
+  ], [
+    AC_MSG_ERROR([Unable to find libresolv which is required for z/OS])
+  ])
+])
+
 dnl resolve lib?
 AC_CHECK_FUNC(strcasecmp, , [ AC_CHECK_LIB(resolve, strcasecmp) ])
 

include/ares.h

@@ -39,7 +39,7 @@
 #if defined(_AIX) || defined(__NOVELL_LIBC__) || defined(__NetBSD__) || \
     defined(__minix) || defined(__SYMBIAN32__) || defined(__INTEGRITY) || \
     defined(ANDROID) || defined(__ANDROID__) || defined(__OpenBSD__) || \
-    defined(__QNXNTO__)
+    defined(__QNXNTO__) || defined(__MVS__)
 #include <sys/select.h>
 #endif
 #if (defined(NETWARE) && !defined(__NOVELL_LIBC__))

src/lib/ares_init.c

@@ -1472,7 +1472,58 @@ static int init_by_resolv_conf(ares_channel channel)
     /* Catch the case when all the above checks fail (which happens when there
        is no network card or the cable is unplugged) */
     status = ARES_EFILE;
+#elif defined(__MVS__)
+
+  struct __res_state *res = 0;
+  int count4, count6;
+  __STATEEXTIPV6 *v6;
+  struct server_state *pserver
+  if (0 == res) {
+    int rc = res_init();
+    while (rc == -1 && h_errno == TRY_AGAIN) {
+      rc = res_init();
+    }
+    if (rc == -1) {
+      return ARES_ENOMEM;
+    }
+    res = __res();
+  }
 
+  v6 = res->__res_extIPv6;
+  count4 = res->nscount;
+  if (v6) {
+    count6 = v6->__stat_nscount;
+  } else {
+    count6 = 0;
+  }
+
+  nservers = count4 + count6;
+  servers = ares_malloc(nservers * sizeof(struct server_state));
+  if (!servers)
+    return ARES_ENOMEM;
+
+  memset(servers, 0, nservers * sizeof(struct server_state));
+
+  pserver = servers;
+  for (int i = 0; i < count4; ++i, ++pserver) {
+    struct sockaddr_in *addr_in = &(res->nsaddr_list[i]);
+    pserver->addr.addrV4.s_addr = addr_in->sin_addr.s_addr;
+    pserver->addr.family = AF_INET;
+    pserver->addr.udp_port = addr_in->sin_port;
+    pserver->addr.tcp_port = addr_in->sin_port;
+  }
+
+  for (int j = 0; j < count6; ++j, ++pserver) {
+    struct sockaddr_in6 *addr_in = &(v6->__stat_nsaddr_list[j]);
+    memcpy(&(pserver->addr.addr.addr6), &(addr_in->sin6_addr),
+           sizeof(addr_in->sin6_addr));
+    pserver->addr.family = AF_INET6;
+    pserver->addr.udp_port = addr_in->sin6_port;
+    pserver->addr.tcp_port = addr_in->sin6_port;
+  }
+
+  status = ARES_EOF;
+  
 #elif defined(__riscos__)
 
   /* Under RISC OS, name servers are listed in the

src/lib/ares_setup.h

@@ -178,8 +178,11 @@
 /*
  * Android does have the arpa/nameser.h header which is detected by configure
  * but it appears to be empty with recent NDK r7b / r7c, so we undefine here.
+ * z/OS does have the arpa/nameser.h header which is detected by configure
+ * but it is not fully implemented and missing identifiers, so udefine here.
  */
-#if (defined(ANDROID) || defined(__ANDROID__)) && defined(HAVE_ARPA_NAMESER_H)
+#if (defined(ANDROID) || defined(__ANDROID__) || defined(__MVS__)) && \
+    defined(HAVE_ARPA_NAMESER_H)
 #  undef HAVE_ARPA_NAMESER_H
 #endif
 

src/lib/ares_strsplit.c

@@ -13,6 +13,10 @@
  * without express or implied warranty.
  */
 
+#if defined(__MVS__)
+#include <strings.h>
+#endif
+
 #include "ares_setup.h"
 #include "ares_strsplit.h"
 #include "ares.h"