From 20e72128de76c230920c029b169e617866224129 Mon Sep 17 00:00:00 2001
From: Kp <kp@valhallalegends.com>
Date: Fri, 18 Mar 2016 02:05:16 +0000
Subject: [PATCH] Add configure test and fallback code to support ancient
 Windows

Windows 2000 has no support for getaddrinfo.  Five years ago (Apr 5
2011), the addition of tracker support
(7f18afd5d7a0fd4146a4ead16e3de09bc1684bdf) brought a requirement for
getaddrinfo.  Recently, someone with a working Windows 2000 system
reported that Rebirth no longer starts on Windows 2000.  Although such
systems should not be connected to the Internet, they may still need
name resolution on a LAN.  Add a configure test to probe for getaddrinfo
support and fall back to gethostbyname if needed.

Compiling a binary that works on Windows 2000 requires one of:
* using an ancient SDK that does not declare getaddrinfo
* defining _WIN32_WINNT to exclude Windows XP support
* overriding the SConf test to force failure

Fixes: 7f18afd5d7a0fd4146a4ead16e3de09bc1684bdf ("Client-side implementation for Tracker support by Matt 1360 Vandermeulen including improvements in udp_dns_filladdr and IPv4/IPv6 compability; Very little adjustments by me, too including IPv6 support for Windows (untested); Actual tracker code will follow later as seperate branch when it's done")
---
 SConstruct               | 22 ++++++++++++++++++++++
 similar/main/net_udp.cpp | 18 ++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/SConstruct b/SConstruct
index e8b7cc4b0..2910bf8e4 100644
--- a/SConstruct
+++ b/SConstruct
@@ -1743,6 +1743,28 @@ help:always wipe certain freed memory
 	return !strcasecmp(argv[0], argv[0] + 1) && !strncasecmp(argv[0] + 1, argv[0], 1);
 '''
 		self.Compile(context, text='#include <cstring>', main=main, msg='for strcasecmp', successflags=_successflags)
+	@_custom_test
+	def check_getaddrinfo_present(self,context,_successflags={'CPPDEFINES' : ['DXX_HAVE_GETADDRINFO']}):
+		self.Compile(context, text='''
+#ifdef WIN32
+#ifndef _WIN32_WINNT
+#define _WIN32_WINNT 0x0501
+#endif
+#include <winsock2.h>
+#include <ws2tcpip.h>
+#else
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netdb.h>
+#endif
+''', main='''
+	addrinfo *res = nullptr;
+	const addrinfo *hints = nullptr;
+	int i = getaddrinfo("", "", hints, &res);
+	(void)i;
+	freeaddrinfo(res);
+	return 0;
+''', msg='for getaddrinfo', successflags=_successflags)
 	__preferred_compiler_options = (
 		'-fvisibility=hidden',
 		'-Wsuggest-attribute=noreturn',
diff --git a/similar/main/net_udp.cpp b/similar/main/net_udp.cpp
index bdd3694c4..3cce1d670 100644
--- a/similar/main/net_udp.cpp
+++ b/similar/main/net_udp.cpp
@@ -523,6 +523,7 @@ public:
 // Resolve address
 int udp_dns_filladdr_t::apply(sockaddr &addr, socklen_t addrlen, int ai_family, const char *host, uint16_t port)
 {
+#ifdef DXX_HAVE_GETADDRINFO
 	// Variables
 	addrinfo hints{};
 	char sPort[6];
@@ -568,6 +569,23 @@ int udp_dns_filladdr_t::apply(sockaddr &addr, socklen_t addrlen, int ai_family,
 	 */
 	
 	// Free memory
+#else
+	sockaddr_in &sai = reinterpret_cast<sockaddr_in &>(addr);
+	if (addrlen < sizeof(sai))
+		return -1;
+	const auto he = gethostbyname(host);
+	if (!he)
+	{
+		con_printf(CON_URGENT, "udp_dns_filladdr (gethostbyname) failed for host %s", host);
+		nm_messagebox(TXT_ERROR, 1, TXT_OK, "Could not resolve IPv4 address\n%s", host);
+		addr.sa_family = AF_UNSPEC;
+		return -1;
+	}
+	sai = {};
+	sai.sin_family = ai_family;
+	sai.sin_port = htons(port);
+	sai.sin_addr = *reinterpret_cast<const in_addr *>(he->h_addr);
+#endif
 	return 0;
 }