From 0be99f8799e90eaed4e8eeb7d5be7de81dd71360 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Petr=20P=C3=ADsa=C5=99?= <ppisar@redhat.com>
Date: Thu, 11 Apr 2019 18:17:16 +0200
Subject: [PATCH] inet_aton: Use getaddrinfo() if possible
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Socket::inet_aton() used gethostbyname() to process arguments that are
not an IP addres. However, gethostbyname() is not thread-safe and when
called from multiple threads a bogus value can be returned.

This patch does add any new test because a basic inet_aton() usage is
already covered and because reproducing the thread failure would
require flodding DNS servers with thousounds of request.

<https://rt.perl.org/Public/Bug/Display.html?id=97860>
<https://bugzilla.redhat.com/show_bug.cgi?id=1693293>

Signed-off-by: Petr Písař <ppisar@redhat.com>
---
 Socket.xs | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/Socket.xs b/Socket.xs
index e46c93e..65244dd 100644
--- a/Socket.xs
+++ b/Socket.xs
@@ -764,19 +764,33 @@ inet_aton(host)
 	char *	host
 	CODE:
 	{
+#ifdef HAS_GETADDRINFO
+	struct addrinfo *res;
+	struct addrinfo hints = {0,};
+	hints.ai_family = AF_INET;
+	if (!getaddrinfo(host, NULL, &hints, &res)) {
+	    ST(0) = sv_2mortal(newSVpvn(
+		(char *)&(((struct sockaddr_in *)res->ai_addr)->sin_addr.s_addr),
+		4
+	));
+	freeaddrinfo(res);
+	XSRETURN(1);
+    }
+#else
 	struct in_addr ip_address;
 	struct hostent * phe;
-
 	if ((*host != '\0') && inet_aton(host, &ip_address)) {
 		ST(0) = sv_2mortal(newSVpvn((char *)&ip_address, sizeof(ip_address)));
 		XSRETURN(1);
 	}
 #ifdef HAS_GETHOSTBYNAME
+	/* gethostbyname is not thread-safe */
 	phe = gethostbyname(host);
 	if (phe && phe->h_addrtype == AF_INET && phe->h_length == 4) {
 		ST(0) = sv_2mortal(newSVpvn((char *)phe->h_addr, phe->h_length));
 		XSRETURN(1);
 	}
+#endif
 #endif
 	XSRETURN_UNDEF;
 	}
-- 
2.20.1