75 lines
2.5 KiB
C
75 lines
2.5 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Safe gethostname implementation for busybox
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*
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* Copyright (C) 2008 Tito Ragusa <farmatito@tiscali.it>
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*
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* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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*/
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/*
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* SUSv2 guarantees that "Host names are limited to 255 bytes"
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* POSIX.1-2001 guarantees that "Host names (not including the terminating
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* null byte) are limited to HOST_NAME_MAX bytes" (64 bytes on my box).
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*
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* RFC1123 says:
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*
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* The syntax of a legal Internet host name was specified in RFC-952
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* [DNS:4]. One aspect of host name syntax is hereby changed: the
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* restriction on the first character is relaxed to allow either a
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* letter or a digit. Host software MUST support this more liberal
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* syntax.
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*
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* Host software MUST handle host names of up to 63 characters and
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* SHOULD handle host names of up to 255 characters.
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*/
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#include "libbb.h"
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#include <sys/utsname.h>
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/*
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* On success return the current malloced and NUL terminated hostname.
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* On error return malloced and NUL terminated string "?".
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* This is an illegal first character for a hostname.
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* The returned malloced string must be freed by the caller.
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*/
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char* FAST_FUNC safe_gethostname(void)
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{
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struct utsname uts;
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/* The length of the arrays in a struct utsname is unspecified;
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* the fields are terminated by a null byte.
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* Note that there is no standard that says that the hostname
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* set by sethostname(2) is the same string as the nodename field of the
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* struct returned by uname (indeed, some systems allow a 256-byte host-
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* name and an 8-byte nodename), but this is true on Linux. The same holds
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* for setdomainname(2) and the domainname field.
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*/
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/* Uname can fail only if you pass a bad pointer to it. */
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uname(&uts);
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return xstrndup(!uts.nodename[0] ? "?" : uts.nodename, sizeof(uts.nodename));
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}
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/*
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* On success return the current malloced and NUL terminated domainname.
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* On error return malloced and NUL terminated string "?".
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* This is an illegal first character for a domainname.
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* The returned malloced string must be freed by the caller.
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*/
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char* FAST_FUNC safe_getdomainname(void)
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{
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#if defined(__linux__)
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/* The field domainname of struct utsname is Linux specific. */
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struct utsname uts;
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uname(&uts);
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return xstrndup(!uts.domainname[0] ? "?" : uts.domainname, sizeof(uts.domainname));
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#else
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/* We really don't care about people with domain names wider than most screens */
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char buf[256];
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int r = getdomainname(buf, sizeof(buf));
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buf[sizeof(buf)-1] = '\0';
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return xstrdup(r < 0 ? "?" : buf);
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#endif
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}
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