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| -rw-r--r-- | lib/canon-host.c | 79 |
1 files changed, 79 insertions, 0 deletions
diff --git a/lib/canon-host.c b/lib/canon-host.c new file mode 100644 index 000000000..180c86a07 --- /dev/null +++ b/lib/canon-host.c @@ -0,0 +1,79 @@ +/* Host name canonicalization + + Copyright (C) 1995 Free Software Foundation, Inc. + + Written by Miles Bader <miles@gnu.ai.mit.edu> + + This program is free software; you can redistribute it and/or + modify it under the terms of the GNU General Public License as + published by the Free Software Foundation; either version 2, or (at + your option) any later version. + + This program is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ + +#ifdef HAVE_CONFIG_H +#include <config.h> +#endif + +#ifdef HAVE_UNISTD_H +#include <unistd.h> +#endif +#ifdef HAVE_STRING_H +#include <string.h> +#endif +#ifdef HAVE_NETDB_H +#include <netdb.h> +#endif + +#ifdef HAVE_NETINET_IN_H +#include <netinet/in.h> +#endif +#ifdef HAVE_ARPA_INET_H +#include <arpa/inet.h> +#endif + +/* Returns the canonical hostname associated with HOST (allocated in a static + buffer), or 0 if it can't be determined. */ +char * +canon_host (host) + char *host; +{ +#ifdef HAVE_GETHOSTBYNAME + struct hostent *he = gethostbyname (host); + + if (he) + { +#ifdef HAVE_GETHOSTBYADDR + char *addr = 0; + + /* Try and get an ascii version of the numeric host address. */ + switch (he->h_addrtype) + { +#ifdef HAVE_INET_NTOA + case AF_INET: + addr = inet_ntoa (*(struct in_addr *)he->h_addr); + break; +#endif /* HAVE_INET_NTOA */ + } + + 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); +#endif HAVE_GETHOSTBYADDR + + if (he) + return he->h_name; + } + +#else /* ! HAVE_GETHOSTBYNAME */ + return 0; +#endif /* HAVE_GETHOSTBYNAME */ +} |