source: branches/3.2/mindi-busybox/libbb/safe_gethostname.c @ 3232

Last change on this file since 3232 was 3232, checked in by bruno, 5 years ago
  • Update mindi-busybox to 1.21.1
  • Property svn:eol-style set to native
File size: 1.8 KB
Line 
1/* vi: set sw=4 ts=4: */
2/*
3 * Safe gethostname implementation for busybox
4 *
5 * Copyright (C) 2008 Tito Ragusa <farmatito@tiscali.it>
6 *
7 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
8 */
9
10/*
11 * SUSv2 guarantees that "Host names are limited to 255 bytes"
12 * POSIX.1-2001 guarantees that "Host names (not including the terminating
13 * null byte) are limited to HOST_NAME_MAX bytes" (64 bytes on my box).
14 *
15 * RFC1123 says:
16 *
17 * The syntax of a legal Internet host name was specified in RFC-952
18 * [DNS:4].  One aspect of host name syntax is hereby changed: the
19 * restriction on the first character is relaxed to allow either a
20 * letter or a digit.  Host software MUST support this more liberal
21 * syntax.
22 *
23 * Host software MUST handle host names of up to 63 characters and
24 * SHOULD handle host names of up to 255 characters.
25 */
26
27#include "libbb.h"
28#include <sys/utsname.h>
29
30/*
31 * On success return the current malloced and NUL terminated hostname.
32 * On error return malloced and NUL terminated string "?".
33 * This is an illegal first character for a hostname.
34 * The returned malloced string must be freed by the caller.
35 */
36char* FAST_FUNC safe_gethostname(void)
37{
38    struct utsname uts;
39
40    /* The length of the arrays in a struct utsname is unspecified;
41     * the fields are terminated by a null byte.
42     * Note that there is no standard that says that the hostname
43     * set by sethostname(2) is the same string as the nodename field of the
44     * struct returned by uname (indeed, some systems allow a 256-byte host-
45     * name and an 8-byte nodename), but this is true on Linux. The same holds
46     * for setdomainname(2) and the domainname field.
47     */
48
49    /* Uname can fail only if you pass a bad pointer to it. */
50    uname(&uts);
51    return xstrndup(!uts.nodename[0] ? "?" : uts.nodename, sizeof(uts.nodename));
52}
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