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| author | Jim Meyering <jim@meyering.net> | 1999-03-10 15:39:02 +0000 |
|---|---|---|
| committer | Jim Meyering <jim@meyering.net> | 1999-03-10 15:39:02 +0000 |
| commit | b910e6ea14523b8a186793e6c6fa9ac3ba7e8d96 (patch) | |
| tree | 14cbde7c880420bed1358cf8fbd136923fdb5105 | |
| parent | 4ba4999328d9695b23225f2e9acdaedc16cd2188 (diff) | |
| download | coreutils-b910e6ea14523b8a186793e6c6fa9ac3ba7e8d96.tar.xz | |
(canon_host): Don't use he->h_addr directly.
Based on a patch from Savochkin Andrey Vladimirovich.
| -rw-r--r-- | lib/canon-host.c | 22 |
1 files changed, 19 insertions, 3 deletions
diff --git a/lib/canon-host.c b/lib/canon-host.c index 1f6b575ee..0c7eac4f0 100644 --- a/lib/canon-host.c +++ b/lib/canon-host.c @@ -43,6 +43,8 @@ # include <arpa/inet.h> #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) |