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