MacOS legacy: Attempt to support last MacOS PPC release - 10.6

src/lib/ares_sysconfig_mac.c

@@ -53,6 +53,7 @@
 #  include <arpa/inet.h>
 #  include "thirdparty/apple/dnsinfo.h"
 #  include <SystemConfiguration/SCNetworkConfiguration.h>
+#  include <AvailabilityMacros.h>
 #  include "ares.h"
 #  include "ares_private.h"
 
@@ -148,6 +149,7 @@ static ares_status_t read_resolver(const dns_resolver_t *resolver,
     return ARES_SUCCESS;
   }
 
+#if MAC_OS_X_VERSION_MIN_REQUIRED >= 1080 /* MacOS 10.8 */
   /* Check to see if DNS server should be used, base this on if the server is
    * reachable or can be reachable automatically if we send traffic that
    * direction. */
@@ -156,6 +158,7 @@ static ares_status_t read_resolver(const dns_resolver_t *resolver,
          kSCNetworkReachabilityFlagsConnectionOnTraffic))) {
     return ARES_SUCCESS;
   }
+#endif
 
   /* NOTE: it doesn't look like resolver->flags is relevant */
 
@@ -219,7 +222,8 @@ static ares_status_t read_resolver(const dns_resolver_t *resolver,
    *   - resolver->timeout appears unused, always 0, so we ignore this
    *   - resolver->service_identifier doesn't appear relevant to us
    *   - resolver->cid also isn't relevant
-   *   - resolver->if_index we don't need, if_name is used instead.
+   *   - resolver->if_name we won't use since it isn't available in MacOS 10.8
+   *     or earlier, use resolver->if_index instead to then lookup the name.
    */
 
   /* XXX: resolver->search_order appears like it might be relevant, we might
@@ -233,6 +237,8 @@ static ares_status_t read_resolver(const dns_resolver_t *resolver,
     struct ares_addr       addr;
     unsigned short         addrport;
     const struct sockaddr *sockaddr;
+    char                   if_name_str[256] = "";
+    const char            *if_name;
 
     /* UBSAN alignment workaround to fetch memory address */
     memcpy(&sockaddr, resolver->nameserver + i, sizeof(sockaddr));
@@ -262,8 +268,11 @@ static ares_status_t read_resolver(const dns_resolver_t *resolver,
     if (addrport == 0) {
       addrport = port;
     }
+
+    if_name = ares__if_indextoname(resolver->if_index, if_name_str,
+                                   sizeof(if_name_str));
     status = ares__sconfig_append(&sysconfig->sconfig, &addr, addrport,
-                                  addrport, resolver->if_name);
+                                  addrport, if_name);
     if (status != ARES_SUCCESS) {
       return status;
     }

src/lib/thirdparty/apple/README.md

@@ -1,12 +1,18 @@
 The `dnsinfo.h` header was extracted from Apple's OpenSource repository:
-[https://opensource.apple.com/source/configd/configd-963.50.8/dnsinfo/dnsinfo.h](https://opensource.apple.com/source/configd/configd-963.50.8/dnsinfo/dnsinfo.h)
+[https://opensource.apple.com/source/configd/configd-453.19/dnsinfo/dnsinfo.h](https://opensource.apple.com/source/configd/configd-453.19/dnsinfo/dnsinfo.h)
 
-We did make one tweak to this file to put `(void)` as the parameter list for both `dns_configuration_notify_key()`
-and `dns_configuration_copy()` to sidestep compiler warnings in this old header.
+We then had to make a few edits to this file:
+1. Add `AvailabilityMacros.h` header file
+2. conditionalize `reach_flags` in `dns_resolver_t` on MacOS 10.8 or higher, in
+   order to maintain compatibility with the last MacOS PPC release, 10.6.
+3. conditionalize `_dns_configuration_ack()` on MacOS 10.8 or higher.
+4. Update parameter list to `(void)` for both `dns_configuration_notify_key()`
+   and `dns_configuration_copy()` to sidestep compiler warnings in this old
+   header.
 
-NOTE: For legacy MacOS compatibility, we needed to import 963.50.8.  We tried with the
-latest (at this time) of 1109.140.1, and it caused issues with MacPorts still supporting
-MacOS versions 10.8-10.11.  There's really not any reason to not support these if it doesn't
-take much effort if MacPorts still is.
+We had tried initially to use the latest 1109.140.1 which only worked on
+MacOS 11+, then downgraded to 963.50.8 for MacOS 10.8+ support, then finally
+to 453.19 with additional patches.
 
-This is needed to call into `dns_configuration_copy()` and `dns_configuration_free()`.
+This is needed to call into `dns_configuration_copy()` and
+`dns_configuration_free()`.

src/lib/thirdparty/apple/dnsinfo.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2004-2006, 2008, 2009, 2011-2013, 2015-2017 Apple Inc. All rights reserved.
+ * Copyright (c) 2004-2006, 2008, 2009, 2011 Apple Inc. All rights reserved.
  *
  * @APPLE_LICENSE_HEADER_START@
  *
@@ -34,8 +34,9 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
+#include <AvailabilityMacros.h>
 
-#define	DNSINFO_VERSION		20170629
+#define	DNSINFO_VERSION		20111104
 
 #define DEFAULT_SEARCH_ORDER    200000   /* search order for the "default" resolver domain name */
 
@@ -72,23 +73,17 @@ typedef struct {
 	DNS_VAR(uint32_t,		search_order);	/* search_order */
 	DNS_VAR(uint32_t,		if_index);
 	DNS_VAR(uint32_t,		flags);
+#if MAC_OS_X_VERSION_MIN_REQUIRED < 1080 /* MacOS 10.8 */
+	DNS_VAR(uint32_t,		reserved[6]);
+#else
 	DNS_VAR(uint32_t,		reach_flags);	/* SCNetworkReachabilityFlags */
-	DNS_VAR(uint32_t,		service_identifier);
-	DNS_PTR(char *,			cid);		/* configuration identifer */
-	DNS_PTR(char *,			if_name);	/* if_index interface name */
+	DNS_VAR(uint32_t,		reserved[5]);
+#endif
 } dns_resolver_t;
 #pragma pack()
 
 
-#define DNS_RESOLVER_FLAGS_REQUEST_A_RECORDS	0x0002		/* always requesting for A dns records in queries */
-#define DNS_RESOLVER_FLAGS_REQUEST_AAAA_RECORDS	0x0004		/* always requesting for AAAA dns records in queries */
-
-#define	DNS_RESOLVER_FLAGS_REQUEST_ALL_RECORDS	\
-	(DNS_RESOLVER_FLAGS_REQUEST_A_RECORDS | DNS_RESOLVER_FLAGS_REQUEST_AAAA_RECORDS)
-
-#define DNS_RESOLVER_FLAGS_SCOPED		0x1000		/* configuration is for scoped questions */
-#define DNS_RESOLVER_FLAGS_SERVICE_SPECIFIC	0x2000		/* configuration is service-specific */
-#define DNS_RESOLVER_FLAGS_SUPPLEMENTAL		0x4000		/* supplemental match configuration */
+#define DNS_RESOLVER_FLAGS_SCOPED	1		/* configuration is for scoped questions */
 
 
 #pragma pack(4)
@@ -97,10 +92,7 @@ typedef struct {
 	DNS_PTR(dns_resolver_t **,	resolver);
 	DNS_VAR(int32_t,		n_scoped_resolver);	/* "scoped" resolver configurations */
 	DNS_PTR(dns_resolver_t **,	scoped_resolver);
-	DNS_VAR(uint64_t,		generation);
-	DNS_VAR(int32_t,		n_service_specific_resolver);
-	DNS_PTR(dns_resolver_t **,	service_specific_resolver);
-	DNS_VAR(uint32_t,		version);
+	DNS_VAR(uint32_t,		reserved[5]);
 } dns_config_t;
 #pragma pack()
 
@@ -119,9 +111,11 @@ dns_configuration_copy		(void)				__OSX_AVAILABLE_STARTING(__MAC_10_4,__IPHONE_2
 void
 dns_configuration_free		(dns_config_t	*config)	__OSX_AVAILABLE_STARTING(__MAC_10_4,__IPHONE_2_0);
 
+#if MAC_OS_X_VERSION_MIN_REQUIRED >= 1080
 void
 _dns_configuration_ack		(dns_config_t	*config,
 				 const char	*bundle_id)	__OSX_AVAILABLE_STARTING(__MAC_10_8, __IPHONE_6_0);
+#endif
 
 __END_DECLS