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-rw-r--r--src/resolve/resolved-util.c84
1 files changed, 84 insertions, 0 deletions
diff --git a/src/resolve/resolved-util.c b/src/resolve/resolved-util.c
new file mode 100644
index 0000000..00abada
--- /dev/null
+++ b/src/resolve/resolved-util.c
@@ -0,0 +1,84 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "dns-def.h"
+#include "dns-domain.h"
+#include "hostname-util.h"
+#include "idn-util.h"
+#include "resolved-util.h"
+#include "utf8.h"
+
+int resolve_system_hostname(char **full_hostname, char **first_label) {
+ _cleanup_free_ char *h = NULL, *n = NULL;
+#if HAVE_LIBIDN2
+ _cleanup_free_ char *utf8 = NULL;
+#elif HAVE_LIBIDN
+ int k;
+#endif
+ char label[DNS_LABEL_MAX];
+ const char *p, *decoded;
+ int r;
+
+ /* Return the full hostname in *full_hostname, if nonnull.
+ *
+ * Extract and normalize the first label of the locally configured hostname, check it's not
+ * "localhost", and return it in *first_label, if nonnull. */
+
+ r = gethostname_strict(&h);
+ if (r < 0)
+ return log_debug_errno(r, "Can't determine system hostname: %m");
+
+ p = h;
+ r = dns_label_unescape(&p, label, sizeof label, 0);
+ if (r < 0)
+ return log_debug_errno(r, "Failed to unescape hostname: %m");
+ if (r == 0)
+ return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+ "Couldn't find a single label in hostname.");
+
+#if HAVE_LIBIDN || HAVE_LIBIDN2
+ r = dlopen_idn();
+ if (r < 0) {
+ log_debug_errno(r, "Failed to initialize IDN support, ignoring: %m");
+ decoded = label; /* no decoding */
+ } else
+#endif
+ {
+#if HAVE_LIBIDN2
+ r = sym_idn2_to_unicode_8z8z(label, &utf8, 0);
+ if (r != IDN2_OK)
+ return log_debug_errno(SYNTHETIC_ERRNO(EUCLEAN),
+ "Failed to undo IDNA: %s", sym_idn2_strerror(r));
+ assert(utf8_is_valid(utf8));
+
+ r = strlen(utf8);
+ decoded = utf8;
+#elif HAVE_LIBIDN
+ k = dns_label_undo_idna(label, r, label, sizeof label);
+ if (k < 0)
+ return log_debug_errno(k, "Failed to undo IDNA: %m");
+ if (k > 0)
+ r = k;
+
+ if (!utf8_is_valid(label))
+ return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+ "System hostname is not UTF-8 clean.");
+ decoded = label;
+#else
+ decoded = label; /* no decoding */
+#endif
+ }
+
+ r = dns_label_escape_new(decoded, r, &n);
+ if (r < 0)
+ return log_debug_errno(r, "Failed to escape hostname: %m");
+
+ if (is_localhost(n))
+ return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+ "System hostname is 'localhost', ignoring.");
+
+ if (full_hostname)
+ *full_hostname = TAKE_PTR(h);
+ if (first_label)
+ *first_label = TAKE_PTR(n);
+ return 0;
+}