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-rw-r--r--src/libbasic/hostname-util.c252
1 files changed, 252 insertions, 0 deletions
diff --git a/src/libbasic/hostname-util.c b/src/libbasic/hostname-util.c
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+++ b/src/libbasic/hostname-util.c
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+/***
+ This file is part of systemd.
+
+ Copyright 2015 Lennart Poettering
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <errno.h>
+#include <limits.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/utsname.h>
+#include <unistd.h>
+
+#include "fd-util.h"
+#include "fileio.h"
+#include "hostname-util.h"
+#include "macro.h"
+#include "string-util.h"
+
+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 host name */
+ if (streq(u.nodename, "(none)"))
+ return false;
+
+ return true;
+}
+
+char* gethostname_malloc(void) {
+ struct utsname u;
+
+ /* 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);
+
+ if (isempty(u.nodename) || streq(u.nodename, "(none)"))
+ return strdup(u.sysname);
+
+ return strdup(u.nodename);
+}
+
+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;
+}
+
+static bool hostname_valid_char(char c) {
+ return
+ (c >= 'a' && c <= 'z') ||
+ (c >= 'A' && c <= 'Z') ||
+ (c >= '0' && c <= '9') ||
+ c == '-' ||
+ c == '_' ||
+ c == '.';
+}
+
+/**
+ * Check if s looks like a valid host name 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;
+
+ 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 = true; *p; p++) {
+ if (*p == '.') {
+ if (dot)
+ return false;
+
+ dot = true;
+ n_dots++;
+ } else {
+ if (!hostname_valid_char(*p))
+ return false;
+
+ dot = false;
+ }
+ }
+
+ if (dot && (n_dots < 2 || !allow_trailing_dot))
+ 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;
+
+ assert(s);
+
+ strshorten(s, HOST_NAME_MAX);
+
+ for (p = s, d = s, dot = true; *p; p++) {
+ if (*p == '.') {
+ if (dot)
+ continue;
+
+ *(d++) = '.';
+ dot = true;
+ } else if (hostname_valid_char(*p)) {
+ *(d++) = *p;
+ dot = false;
+ }
+
+ }
+
+ if (dot && d > s)
+ d[-1] = 0;
+ else
+ *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 strcaseeq(hostname, "localhost") ||
+ strcaseeq(hostname, "localhost.") ||
+ strcaseeq(hostname, "localhost.localdomain") ||
+ strcaseeq(hostname, "localhost.localdomain.") ||
+ endswith_no_case(hostname, ".localhost") ||
+ endswith_no_case(hostname, ".localhost.") ||
+ endswith_no_case(hostname, ".localhost.localdomain") ||
+ endswith_no_case(hostname, ".localhost.localdomain.");
+}
+
+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.");
+}
+
+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 read_hostname_config(const char *path, char **hostname) {
+ _cleanup_fclose_ FILE *f = NULL;
+ char l[LINE_MAX];
+ char *name = NULL;
+
+ assert(path);
+ assert(hostname);
+
+ f = fopen(path, "re");
+ if (!f)
+ return -errno;
+
+ /* may have comments, ignore them */
+ FOREACH_LINE(l, f, return -errno) {
+ truncate_nl(l);
+ if (l[0] != '\0' && l[0] != '#') {
+ /* found line with value */
+ name = hostname_cleanup(l);
+ name = strdup(name);
+ if (!name)
+ return -ENOMEM;
+ break;
+ }
+ }
+
+ if (!name)
+ /* no non-empty line found */
+ return -ENOENT;
+
+ *hostname = name;
+ return 0;
+}