network: Implement DHCP Option 119 (Domain Search List) (#5932)

This adds a modified version of dhcp6_option_parse_domainname() that is
able to parse compressed domain names, borrowing the idea from
dns_packet_read_name(). It also adds pieces in networkd-link and
networkd-manager to properly save/load the added option field.

Resolves #2710.

1 files changed, 90 insertions, 0 deletions

diff --git a/src/libsystemd-network/test-sd-dhcp-lease.c b/src/libsystemd-network/test-sd-dhcp-lease.c
new file mode 100644
index 0000000000..0f881809ab
--- /dev/null
+++ b/src/libsystemd-network/test-sd-dhcp-lease.c
@@ -0,0 +1,90 @@
+#include <errno.h>
+
+#include "dhcp-lease-internal.h"
+#include "macro.h"
+#include "string-util.h"
+#include "strv.h"
+
+/* According to RFC1035 section 4.1.4, a domain name in a message can be either:
+ *      - a sequence of labels ending in a zero octet
+ *      - a pointer
+ *      - a sequence of labels ending with a pointer
+ */
+static void test_dhcp_lease_parse_search_domains_basic(void) {
+        int r;
+        _cleanup_strv_free_ char **domains = NULL;
+        static const uint8_t optionbuf[] = {
+                0x03, 'F', 'O', 'O', 0x03, 'B', 'A', 'R', 0x00,
+                0x04, 'A', 'B', 'C', 'D', 0x03, 'E', 'F', 'G', 0x00,
+        };
+
+        r = dhcp_lease_parse_search_domains(optionbuf, sizeof(optionbuf), &domains);
+        assert_se(r == 2);
+        assert_se(streq(domains[0], "FOO.BAR"));
+        assert_se(streq(domains[1], "ABCD.EFG"));
+}
+
+static void test_dhcp_lease_parse_search_domains_ptr(void) {
+        int r;
+        _cleanup_strv_free_ char **domains = NULL;
+        static const uint8_t optionbuf[] = {
+                0x03, 'F', 'O', 'O', 0x00, 0xC0, 0x00,
+        };
+
+        r = dhcp_lease_parse_search_domains(optionbuf, sizeof(optionbuf), &domains);
+        assert_se(r == 2);
+        assert_se(streq(domains[0], "FOO"));
+        assert_se(streq(domains[1], "FOO"));
+}
+
+static void test_dhcp_lease_parse_search_domains_labels_and_ptr(void) {
+        int r;
+        _cleanup_strv_free_ char **domains = NULL;
+        static const uint8_t optionbuf[] = {
+                0x03, 'F', 'O', 'O', 0x03, 'B', 'A', 'R', 0x00,
+                0x03, 'A', 'B', 'C', 0xC0, 0x04,
+        };
+
+        r = dhcp_lease_parse_search_domains(optionbuf, sizeof(optionbuf), &domains);
+        assert_se(r == 2);
+        assert_se(streq(domains[0], "FOO.BAR"));
+        assert_se(streq(domains[1], "ABC.BAR"));
+}
+
+/* Tests for exceptions. */
+
+static void test_dhcp_lease_parse_search_domains_no_data(void) {
+        _cleanup_strv_free_ char **domains = NULL;
+        static const uint8_t optionbuf[3] = {0, 0, 0};
+
+        assert_se(dhcp_lease_parse_search_domains(NULL, 0, &domains) == -ENODATA);
+        assert_se(dhcp_lease_parse_search_domains(optionbuf, 0, &domains) == -ENODATA);
+}
+
+static void test_dhcp_lease_parse_search_domains_loops(void) {
+        _cleanup_strv_free_ char **domains = NULL;
+        static const uint8_t optionbuf[] = {
+                0x03, 'F', 'O', 'O', 0x00, 0x03, 'B', 'A', 'R', 0xC0, 0x06,
+        };
+
+        assert_se(dhcp_lease_parse_search_domains(optionbuf, sizeof(optionbuf), &domains) == -EBADMSG);
+}
+
+static void test_dhcp_lease_parse_search_domains_wrong_len(void) {
+        _cleanup_strv_free_ char **domains = NULL;
+        static const uint8_t optionbuf[] = {
+                0x03, 'F', 'O', 'O', 0x03, 'B', 'A', 'R', 0x00,
+                0x04, 'A', 'B', 'C', 'D', 0x03, 'E', 'F', 'G', 0x00,
+        };
+
+        assert_se(dhcp_lease_parse_search_domains(optionbuf, sizeof(optionbuf) - 5, &domains) == -EBADMSG);
+}
+
+int main(int argc, char *argv[]) {
+        test_dhcp_lease_parse_search_domains_basic();
+        test_dhcp_lease_parse_search_domains_ptr();
+        test_dhcp_lease_parse_search_domains_labels_and_ptr();
+        test_dhcp_lease_parse_search_domains_no_data();
+        test_dhcp_lease_parse_search_domains_loops();
+        test_dhcp_lease_parse_search_domains_wrong_len();
+}