/* SPDX-License-Identifier: LGPL-2.1+ */
#include "nm-sd-adapt-shared.h"
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <sys/utsname.h>
#include <unistd.h>
#include "alloc-util.h"
#include "fd-util.h"
#include "fileio.h"
#include "hostname-util.h"
#include "macro.h"
#include "string-util.h"
#include "strv.h"
#if 0 /* NM_IGNORED */
bool hostname_is_set(void) {
struct utsname u;
assert_se(uname(&u) >= 0);
if (isempty(u.nodename))
return false;
/* This is the built-in kernel default hostname */
if (streq(u.nodename, "(none)"))
return false;
return true;
}
char* gethostname_malloc(void) {
struct utsname u;
const char *s;
/* This call tries to return something useful, either the actual hostname
* or it makes something up. The only reason it might fail is OOM.
* It might even return "localhost" if that's set. */
assert_se(uname(&u) >= 0);
s = u.nodename;
if (isempty(s) || streq(s, "(none)"))
s = FALLBACK_HOSTNAME;
return strdup(s);
}
char* gethostname_short_malloc(void) {
struct utsname u;
const char *s;
/* Like above, but kills the FQDN part if present. */
assert_se(uname(&u) >= 0);
s = u.nodename;
if (isempty(s) || streq(s, "(none)") || s[0] == '.') {
s = FALLBACK_HOSTNAME;
assert(s[0] != '.');
}
return strndup(s, strcspn(s, "."));
}
#endif /* NM_IGNORED */
int gethostname_strict(char **ret) {
struct utsname u;
char *k;
/* This call will rather fail than make up a name. It will not return "localhost" either. */
assert_se(uname(&u) >= 0);
if (isempty(u.nodename))
return -ENXIO;
if (streq(u.nodename, "(none)"))
return -ENXIO;
if (is_localhost(u.nodename))
return -ENXIO;
k = strdup(u.nodename);
if (!k)
return -ENOMEM;
*ret = k;
return 0;
}
bool valid_ldh_char(char c) {
return
(c >= 'a' && c <= 'z') ||
(c >= 'A' && c <= 'Z') ||
(c >= '0' && c <= '9') ||
c == '-';
}
/**
* Check if s looks like a valid hostname or FQDN. This does not do
* full DNS validation, but only checks if the name is composed of
* allowed characters and the length is not above the maximum allowed
* by Linux (c.f. dns_name_is_valid()). Trailing dot is allowed if
* allow_trailing_dot is true and at least two components are present
* in the name. Note that due to the restricted charset and length
* this call is substantially more conservative than
* dns_name_is_valid().
*/
bool hostname_is_valid(const char *s, bool allow_trailing_dot) {
unsigned n_dots = 0;
const char *p;
bool dot, hyphen;
if (isempty(s))
return false;
/* Doesn't accept empty hostnames, hostnames with
* leading dots, and hostnames with multiple dots in a
* sequence. Also ensures that the length stays below
* HOST_NAME_MAX. */
for (p = s, dot = hyphen = true; *p; p++)
if (*p == '.') {
if (dot || hyphen)
return false;
dot = true;
hyphen = false;
n_dots++;
} else if (*p == '-') {
if (dot)
return false;
dot = false;
hyphen = true;
} else {
if (!valid_ldh_char(*p))
return false;
dot = false;
hyphen = false;
}
if (dot && (n_dots < 2 || !allow_trailing_dot))
return false;
if (hyphen)
return false;
if (p-s > HOST_NAME_MAX) /* Note that HOST_NAME_MAX is 64 on
* Linux, but DNS allows domain names
* up to 255 characters */
return false;
return true;
}
char* hostname_cleanup(char *s) {
char *p, *d;
bool dot, hyphen;
assert(s);
for (p = s, d = s, dot = hyphen = true; *p && d - s < HOST_NAME_MAX; p++)
if (*p == '.') {
if (dot || hyphen)
continue;
*(d++) = '.';
dot = true;
hyphen = false;
} else if (*p == '-') {
if (dot)
continue;
*(d++) = '-';
dot = false;
hyphen = true;
} else if (valid_ldh_char(*p)) {
*(d++) = *p;
dot = false;
hyphen = false;
}
if (d > s && IN_SET(d[-1], '-', '.'))
/* The dot can occur at most once, but we might have multiple
* hyphens, hence the loop */
d--;
*d = 0;
return s;
}
bool is_localhost(const char *hostname) {
assert(hostname);
/* This tries to identify local host and domain names
* described in RFC6761 plus the redhatism of localdomain */
return STRCASE_IN_SET(
hostname,
"localhost",
"localhost.",
"localhost.localdomain",
"localhost.localdomain.") ||
endswith_no_case(hostname, ".localhost") ||
endswith_no_case(hostname, ".localhost.") ||
endswith_no_case(hostname, ".localhost.localdomain") ||
endswith_no_case(hostname, ".localhost.localdomain.");
}
#if 0 /* NM_IGNORED */
bool is_gateway_hostname(const char *hostname) {
assert(hostname);
/* This tries to identify the valid syntaxes for the our
* synthetic "gateway" host. */
return
strcaseeq(hostname, "_gateway") || strcaseeq(hostname, "_gateway.")
#if ENABLE_COMPAT_GATEWAY_HOSTNAME
|| strcaseeq(hostname, "gateway") || strcaseeq(hostname, "gateway.")
#endif
;
}
int sethostname_idempotent(const char *s) {
char buf[HOST_NAME_MAX + 1] = {};
assert(s);
if (gethostname(buf, sizeof(buf)) < 0)
return -errno;
if (streq(buf, s))
return 0;
if (sethostname(s, strlen(s)) < 0)
return -errno;
return 1;
}
int shorten_overlong(const char *s, char **ret) {
char *h, *p;
/* Shorten an overlong name to HOST_NAME_MAX or to the first dot,
* whatever comes earlier. */
assert(s);
h = strdup(s);
if (!h)
return -ENOMEM;
if (hostname_is_valid(h, false)) {
*ret = h;
return 0;
}
p = strchr(h, '.');
if (p)
*p = 0;
strshorten(h, HOST_NAME_MAX);
if (!hostname_is_valid(h, false)) {
free(h);
return -EDOM;
}
*ret = h;
return 1;
}
int read_etc_hostname_stream(FILE *f, char **ret) {
int r;
assert(f);
assert(ret);
for (;;) {
_cleanup_free_ char *line = NULL;
char *p;
r = read_line(f, LONG_LINE_MAX, &line);
if (r < 0)
return r;
if (r == 0) /* EOF without any hostname? the file is empty, let's treat that exactly like no file at all: ENOENT */
return -ENOENT;
p = strstrip(line);
/* File may have empty lines or comments, ignore them */
if (!IN_SET(*p, '\0', '#')) {
char *copy;
hostname_cleanup(p); /* normalize the hostname */
if (!hostname_is_valid(p, true)) /* check that the hostname we return is valid */
return -EBADMSG;
copy = strdup(p);
if (!copy)
return -ENOMEM;
*ret = copy;
return 0;
}
}
}
int read_etc_hostname(const char *path, char **ret) {
_cleanup_fclose_ FILE *f = NULL;
assert(ret);
if (!path)
path = "/etc/hostname";
f = fopen(path, "re");
if (!f)
return -errno;
return read_etc_hostname_stream(f, ret);
}
#endif /* NM_IGNORED */