From b910e6ea14523b8a186793e6c6fa9ac3ba7e8d96 Mon Sep 17 00:00:00 2001 From: Jim Meyering Date: Wed, 10 Mar 1999 15:39:02 +0000 Subject: [PATCH] (canon_host): Don't use he->h_addr directly. Based on a patch from Savochkin Andrey Vladimirovich. --- lib/canon-host.c | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) diff --git a/lib/canon-host.c b/lib/canon-host.c index 1f6b575..0c7eac4 100644 --- a/lib/canon-host.c +++ b/lib/canon-host.c @@ -43,6 +43,8 @@ # include #endif +void free (); + /* Returns the canonical hostname associated with HOST (allocated in a static buffer), or 0 if it can't be determined. */ char * @@ -67,9 +69,23 @@ canon_host (const char *host) } if (addr && strcmp (he->h_name, addr) == 0) - /* gethostbyname() cheated! Lookup the host name via the address - this time to get the actual host name. */ - he = gethostbyaddr (he->h_addr, he->h_length, he->h_addrtype); + { + /* gethostbyname has returned a string representation of the IP + address, for example, "127.0.0.1". So now, look up the host + name via the address. Although it may seem reasonable to look + up the host name via the address, we must not pass `he->h_addr' + directly to gethostbyaddr because on some systems he->h_addr + is located in a static library buffer that is reused in the + gethostbyaddr call. Make a copy and use that instead. */ + char *h_addr_copy = strdup (he->h_addr); + if (h_addr_copy == NULL) + he = NULL; + else + { + he = gethostbyaddr (h_addr_copy, he->h_length, he->h_addrtype); + free (h_addr_copy); + } + } # endif /* HAVE_GETHOSTBYADDR */ if (he) -- 2.7.4