From 678964b242342684455e5889d4e7e6e514bf77b0 Mon Sep 17 00:00:00 2001
From: Thiago Macieira <thiago.macieira@intel.com>
Date: Mon, 8 May 2023 19:49:04 -0700
Subject: [PATCH] QDnsLookup/Unix: add support for res_setservers()
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This API is found on FreeBSD, Darwin, Solaris, AIX, and Android Bionic.
That means we complement IPv6 support for most platforms.

Test on macOS:

$ $objdir/tests/manual/qdnslookup/qdnslookup @fe80::1e1b:dff:fee2:49e6%en0
; <<>> QDnsLookup 6.6.0
;; status: NoError
;; QUESTION:
;qt-project.org                 IN A

;; ANSWER:
qt-project.org            3336  IN A    52.18.144.254

;; Query time: 2 ms
;; SERVER: fe80::1e1b:dff:fee2:49e6%en0#53

Dnsmasq log on the server confirms it was queried.

Change-Id: I3e3bfef633af4130a03afffd175d59c67faa463f
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
---
 src/network/configure.cmake            | 23 +++++++++++++++++++++++
 src/network/kernel/qdnslookup_unix.cpp | 14 ++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/src/network/configure.cmake b/src/network/configure.cmake
index a26f979d3c..d0417d6e3a 100644
--- a/src/network/configure.cmake
+++ b/src/network/configure.cmake
@@ -119,6 +119,25 @@ int main()
 "
 )
 
+# res_setserver
+qt_config_compile_test(res_setservers
+    LABEL "res_setservers()"
+    LIBRARIES
+        WrapResolv::WrapResolv
+    CODE
+"#include <sys/types.h>
+#include <netinet/in.h>
+#include <resolv.h>
+int main()
+{
+    union res_sockaddr_union sa;
+    res_state s = nullptr;
+    res_setservers(s, &sa, 1);
+    return 0;
+}
+"
+)
+
 # sctp
 qt_config_compile_test(sctp
     LABEL "SCTP support"
@@ -235,6 +254,10 @@ qt_feature("res_ninit" PRIVATE
     CONDITION TEST_res_ninit
     AUTODETECT UNIX
 )
+qt_feature("res_setservers" PRIVATE
+    LABEL "res_setservers()"
+    CONDITION QT_FEATURE_res_ninit AND TEST_res_setservers
+)
 qt_feature("securetransport" PUBLIC
     LABEL "SecureTransport"
     CONDITION APPLE
diff --git a/src/network/kernel/qdnslookup_unix.cpp b/src/network/kernel/qdnslookup_unix.cpp
index 240ace3c3c..0e10e8f928 100644
--- a/src/network/kernel/qdnslookup_unix.cpp
+++ b/src/network/kernel/qdnslookup_unix.cpp
@@ -24,6 +24,19 @@ QT_BEGIN_NAMESPACE
 
 using namespace Qt::StringLiterals;
 
+#if QT_CONFIG(res_setservers)
+// https://www.ibm.com/docs/en/i/7.3?topic=ssw_ibm_i_73/apis/ressetservers.html
+// https://docs.oracle.com/cd/E86824_01/html/E54774/res-setservers-3resolv.html
+static const char *applyNameServer(res_state state, const QHostAddress &nameserver, quint16 port)
+{
+    if (nameserver.isNull())
+        return nullptr;
+    union res_sockaddr_union u;
+    setSockaddr(reinterpret_cast<sockaddr *>(&u.sin), nameserver, port);
+    res_setservers(state, &u, 1);
+    return nullptr;
+}
+#else
 template <typename T> void setNsMap(T &ext, std::enable_if_t<sizeof(T::nsmap) != 0, uint16_t> v)
 {
     // Set nsmap[] to indicate that nsaddrs[0] is an IPv6 address
@@ -84,6 +97,7 @@ static const char *applyNameServer(res_state state, const QHostAddress &nameserv
     }
     return nullptr;
 }
+#endif // !QT_CONFIG(res_setservers)
 
 void QDnsLookupRunnable::query(const int requestType, const QByteArray &requestName, const QHostAddress &nameserver, QDnsLookupReply *reply)
 {