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-rw-r--r--src/shared/hostname-setup.c213
1 files changed, 213 insertions, 0 deletions
diff --git a/src/shared/hostname-setup.c b/src/shared/hostname-setup.c
new file mode 100644
index 0000000..137c29a
--- /dev/null
+++ b/src/shared/hostname-setup.c
@@ -0,0 +1,213 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/utsname.h>
+#include <unistd.h>
+
+#include "alloc-util.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "fs-util.h"
+#include "hostname-setup.h"
+#include "hostname-util.h"
+#include "log.h"
+#include "macro.h"
+#include "proc-cmdline.h"
+#include "string-table.h"
+#include "string-util.h"
+
+static int sethostname_idempotent_full(const char *s, bool really) {
+ struct utsname u;
+
+ assert(s);
+
+ assert_se(uname(&u) >= 0);
+
+ if (streq_ptr(s, u.nodename))
+ return 0;
+
+ if (really &&
+ sethostname(s, strlen(s)) < 0)
+ return -errno;
+
+ return 1;
+}
+
+int sethostname_idempotent(const char *s) {
+ return sethostname_idempotent_full(s, true);
+}
+
+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, 0)) {
+ *ret = h;
+ return 0;
+ }
+
+ p = strchr(h, '.');
+ if (p)
+ *p = 0;
+
+ strshorten(h, HOST_NAME_MAX);
+
+ if (!hostname_is_valid(h, 0)) {
+ 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;
+
+ r = read_stripped_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;
+
+ /* File may have empty lines or comments, ignore them */
+ if (IN_SET(line[0], '\0', '#'))
+ continue;
+
+ hostname_cleanup(line); /* normalize the hostname */
+
+ if (!hostname_is_valid(line, VALID_HOSTNAME_TRAILING_DOT)) /* check that the hostname we return is valid */
+ return -EBADMSG;
+
+ *ret = TAKE_PTR(line);
+ 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);
+}
+
+void hostname_update_source_hint(const char *hostname, HostnameSource source) {
+ int r;
+
+ /* Why save the value and not just create a flag file? This way we will
+ * notice if somebody sets the hostname directly (not going through hostnamed).
+ */
+
+ if (source == HOSTNAME_DEFAULT) {
+ r = write_string_file("/run/systemd/default-hostname", hostname,
+ WRITE_STRING_FILE_CREATE | WRITE_STRING_FILE_ATOMIC);
+ if (r < 0)
+ log_warning_errno(r, "Failed to create \"/run/systemd/default-hostname\": %m");
+ } else
+ unlink_or_warn("/run/systemd/default-hostname");
+}
+
+int hostname_setup(bool really) {
+ _cleanup_free_ char *b = NULL;
+ const char *hn = NULL;
+ HostnameSource source;
+ bool enoent = false;
+ int r;
+
+ r = proc_cmdline_get_key("systemd.hostname", 0, &b);
+ if (r < 0)
+ log_warning_errno(r, "Failed to retrieve system hostname from kernel command line, ignoring: %m");
+ else if (r > 0) {
+ if (hostname_is_valid(b, VALID_HOSTNAME_TRAILING_DOT)) {
+ hn = b;
+ source = HOSTNAME_TRANSIENT;
+ } else {
+ log_warning("Hostname specified on kernel command line is invalid, ignoring: %s", b);
+ b = mfree(b);
+ }
+ }
+
+ if (!hn) {
+ r = read_etc_hostname(NULL, &b);
+ if (r < 0) {
+ if (r == -ENOENT)
+ enoent = true;
+ else
+ log_warning_errno(r, "Failed to read configured hostname: %m");
+ } else {
+ hn = b;
+ source = HOSTNAME_STATIC;
+ }
+ }
+
+ if (!hn) {
+ _cleanup_free_ char *buf = NULL;
+
+ /* Don't override the hostname if it is already set and not explicitly configured */
+
+ r = gethostname_full(GET_HOSTNAME_ALLOW_LOCALHOST, &buf);
+ if (r == -ENOMEM)
+ return log_oom();
+ if (r >= 0) {
+ log_debug("No hostname configured, leaving existing hostname <%s> in place.", buf);
+ return 0;
+ }
+
+ if (enoent)
+ log_info("No hostname configured, using default hostname.");
+
+ hn = b = get_default_hostname();
+ if (!hn)
+ return log_oom();
+
+ source = HOSTNAME_DEFAULT;
+
+ }
+
+ r = sethostname_idempotent_full(hn, really);
+ if (r < 0)
+ return log_warning_errno(r, "Failed to set hostname to <%s>: %m", hn);
+ if (r == 0)
+ log_debug("Hostname was already set to <%s>.", hn);
+ else
+ log_info("Hostname %s to <%s>.",
+ really ? "set" : "would have been set",
+ hn);
+
+ if (really)
+ hostname_update_source_hint(hn, source);
+
+ return r;
+}
+
+static const char* const hostname_source_table[] = {
+ [HOSTNAME_STATIC] = "static",
+ [HOSTNAME_TRANSIENT] = "transient",
+ [HOSTNAME_DEFAULT] = "default",
+};
+
+DEFINE_STRING_TABLE_LOOKUP(hostname_source, HostnameSource);