e2054217d5
No functional change, just moving a bunch of things around. Before we needed a rather complicated setup to test hostname_setup(), because the code was in src/core/. When things are moved to src/shared/ we can just test it as any function. The test is still "unsafe" because hostname_setup() may modify the hostname.
193 lines
5.8 KiB
C
193 lines
5.8 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include <errno.h>
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#include <limits.h>
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#include <stdio.h>
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#include <sys/utsname.h>
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#include <unistd.h>
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#include "alloc-util.h"
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#include "hostname-util.h"
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#include "string-util.h"
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#include "strv.h"
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char* gethostname_malloc(void) {
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struct utsname u;
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const char *s;
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/* This call tries to return something useful, either the actual hostname
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* or it makes something up. The only reason it might fail is OOM.
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* It might even return "localhost" if that's set. */
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assert_se(uname(&u) >= 0);
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s = u.nodename;
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if (isempty(s) || streq(s, "(none)"))
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s = FALLBACK_HOSTNAME;
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return strdup(s);
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}
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char* gethostname_short_malloc(void) {
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struct utsname u;
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const char *s;
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/* Like above, but kills the FQDN part if present. */
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assert_se(uname(&u) >= 0);
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s = u.nodename;
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if (isempty(s) || streq(s, "(none)") || s[0] == '.') {
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s = FALLBACK_HOSTNAME;
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assert(s[0] != '.');
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}
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return strndup(s, strcspn(s, "."));
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}
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int gethostname_strict(char **ret) {
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struct utsname u;
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char *k;
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/* This call will rather fail than make up a name. It will not return "localhost" either. */
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assert_se(uname(&u) >= 0);
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if (isempty(u.nodename))
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return -ENXIO;
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if (streq(u.nodename, "(none)"))
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return -ENXIO;
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if (is_localhost(u.nodename))
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return -ENXIO;
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k = strdup(u.nodename);
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if (!k)
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return -ENOMEM;
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*ret = k;
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return 0;
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}
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bool valid_ldh_char(char c) {
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/* "LDH" → "Letters, digits, hyphens", as per RFC 5890, Section 2.3.1 */
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return
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(c >= 'a' && c <= 'z') ||
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(c >= 'A' && c <= 'Z') ||
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(c >= '0' && c <= '9') ||
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c == '-';
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}
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bool hostname_is_valid(const char *s, ValidHostnameFlags flags) {
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unsigned n_dots = 0;
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const char *p;
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bool dot, hyphen;
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/* Check if s looks like a valid hostname or FQDN. This does not do full DNS validation, but only
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* checks if the name is composed of allowed characters and the length is not above the maximum
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* allowed by Linux (c.f. dns_name_is_valid()). A trailing dot is allowed if
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* VALID_HOSTNAME_TRAILING_DOT flag is set and at least two components are present in the name. Note
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* that due to the restricted charset and length this call is substantially more conservative than
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* dns_name_is_valid(). Doesn't accept empty hostnames, hostnames with leading dots, and hostnames
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* with multiple dots in a sequence. Doesn't allow hyphens at the beginning or end of label. */
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if (isempty(s))
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return false;
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if (streq(s, ".host")) /* Used by the container logic to denote the "root container" */
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return FLAGS_SET(flags, VALID_HOSTNAME_DOT_HOST);
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for (p = s, dot = hyphen = true; *p; p++)
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if (*p == '.') {
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if (dot || hyphen)
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return false;
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dot = true;
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hyphen = false;
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n_dots++;
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} else if (*p == '-') {
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if (dot)
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return false;
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dot = false;
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hyphen = true;
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} else {
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if (!valid_ldh_char(*p))
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return false;
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dot = false;
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hyphen = false;
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}
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if (dot && (n_dots < 2 || !FLAGS_SET(flags, VALID_HOSTNAME_TRAILING_DOT)))
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return false;
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if (hyphen)
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return false;
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if (p-s > HOST_NAME_MAX) /* Note that HOST_NAME_MAX is 64 on Linux, but DNS allows domain names up to
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* 255 characters */
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return false;
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return true;
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}
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char* hostname_cleanup(char *s) {
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char *p, *d;
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bool dot, hyphen;
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assert(s);
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for (p = s, d = s, dot = hyphen = true; *p && d - s < HOST_NAME_MAX; p++)
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if (*p == '.') {
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if (dot || hyphen)
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continue;
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*(d++) = '.';
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dot = true;
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hyphen = false;
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} else if (*p == '-') {
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if (dot)
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continue;
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*(d++) = '-';
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dot = false;
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hyphen = true;
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} else if (valid_ldh_char(*p)) {
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*(d++) = *p;
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dot = false;
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hyphen = false;
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}
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if (d > s && IN_SET(d[-1], '-', '.'))
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/* The dot can occur at most once, but we might have multiple
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* hyphens, hence the loop */
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d--;
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*d = 0;
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return s;
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}
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bool is_localhost(const char *hostname) {
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assert(hostname);
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/* This tries to identify local host and domain names
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* described in RFC6761 plus the redhatism of localdomain */
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return STRCASE_IN_SET(
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hostname,
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"localhost",
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"localhost.",
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"localhost.localdomain",
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"localhost.localdomain.") ||
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endswith_no_case(hostname, ".localhost") ||
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endswith_no_case(hostname, ".localhost.") ||
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endswith_no_case(hostname, ".localhost.localdomain") ||
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endswith_no_case(hostname, ".localhost.localdomain.");
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}
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