| Subject: | Socket::inet_aton() is not thread safe |
Socket::inet_aton() subroutine not only translates text representation of and IP address, it also can translate a domain name. This second feature uses gethostbyname() function from a standard C library. However, gethostbyname() is not tread safe. This results into various bugs when Socket::inet_aton() is called in parallel from more threads.
A similar issue was already reported many years ago to Perl porters <https://rt.perl.org/Public/Bug/Display.html?id=97860> without any resolution.
An attached patch fixes this issue by using getaddrinfo() instead of gethostbyname() inside the Socket::inet_aton() implementation if available. getaddrinfo() is tread safe.
| Subject: | 0001-inet_aton-Use-getaddrinfo-if-possible.patch |
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
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
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 PÃsaÅ <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