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Blame SOURCES/0135-login-use-IPv4-on-IPv4-mapping-to-IPv6.patch

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From 7a1a825c7b77785f256e05b1e3ac7676c7485a5c Mon Sep 17 00:00:00 2001
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From: Karel Zak <kzak@redhat.com>
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Date: Tue, 4 Jul 2017 12:50:39 +0200
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Subject: [PATCH 135/135] login: use IPv4 on IPv4-mapping-to-IPv6
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It seems that on some systems (e.g. RHEL7) the libc function
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getaddrinfo() is not able to translate ::ffff: address to IPv4. The
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result is 0.0.0.0 host address in the last(1) and utmpdump(1) output.
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 /sbin/login -h "::ffff:192.168.1.7"
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utmpdump:
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  [7] [03926] [1   ] [user1   ] [pts/1       ] [::ffff:192.168.1.7  ] [0.0.0.0        ] [Thu May 12 17:49:50 2016    ]
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Not sure if this is about order of the getaddrinfo() results, system
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configuration or libc version. It's irrelevant for login(1). We have
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to be robust enough to write usable address to log files everywhere.
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The solution is to detect IPv4-mapping-to-IPv6 and use IPv4 for utmp.
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Upstream: http://github.com/karelzak/util-linux/commit/1c8792f1ae7fa38cf1d4418ad99c207f65dfdb1a
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Addresses: https://bugzilla.redhat.com/show_bug.cgi?id=1296233
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Signed-off-by: Karel Zak <kzak@redhat.com>
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---
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 login-utils/login.c | 9 ++++++++-
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 1 file changed, 8 insertions(+), 1 deletion(-)
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diff --git a/login-utils/login.c b/login-utils/login.c
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index e0e960f88..5c36953ef 100644
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--- a/login-utils/login.c
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+++ b/login-utils/login.c
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@@ -1101,8 +1101,15 @@ static void init_remote_info(struct login_context *cxt, char *remotehost)
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 		} else if (info->ai_family == AF_INET6) {
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 			struct sockaddr_in6 *sa =
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 				     (struct sockaddr_in6 *) info->ai_addr;
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+#ifdef IN6_IS_ADDR_V4MAPPED
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+			if (IN6_IS_ADDR_V4MAPPED(&sa->sin6_addr)) {
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+				const uint8_t *bytes = sa->sin6_addr.s6_addr;
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+				struct in_addr addr = { *(const in_addr_t *) (bytes + 12) };
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-			memcpy(cxt->hostaddress, &(sa->sin6_addr), sizeof(sa->sin6_addr));
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+				memcpy(cxt->hostaddress, &addr, sizeof(struct in_addr));
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+			} else
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+#endif
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+				memcpy(cxt->hostaddress, &(sa->sin6_addr), sizeof(sa->sin6_addr));
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 		}
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 		freeaddrinfo(info);
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 	}
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-- 
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2.13.6
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