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authorLennart Poettering <lennart@poettering.net>2015-11-30 19:39:19 +0100
committerLennart Poettering <lennart@poettering.net>2015-11-30 19:42:35 +0100
commit50dee79bfbe0782a342ef864b28d7d6613c0b1fb (patch)
treed7019c6315f71bd631f7efacf44ec92494922778 /src
parentc6cefd13eb55c8124a01e90021282f8610a05012 (diff)
dns-domain: check resulting domain name length in dns_name_to_wire_format()
Let's better be safe than sorry.
Diffstat (limited to 'src')
-rw-r--r--src/shared/dns-domain.c19
-rw-r--r--src/test/test-dns-domain.c37
2 files changed, 48 insertions, 8 deletions
diff --git a/src/shared/dns-domain.c b/src/shared/dns-domain.c
index ba6eff8f60..03c0107308 100644
--- a/src/shared/dns-domain.c
+++ b/src/shared/dns-domain.c
@@ -864,7 +864,7 @@ bool dns_name_is_single_label(const char *name) {
return dns_name_is_root(name);
}
-/* Encode a domain name according to RFC 1035 Section 3.1 */
+/* Encode a domain name according to RFC 1035 Section 3.1, without compression */
int dns_name_to_wire_format(const char *domain, uint8_t *buffer, size_t len) {
uint8_t *label_length, *out;
int r;
@@ -875,24 +875,35 @@ int dns_name_to_wire_format(const char *domain, uint8_t *buffer, size_t len) {
out = buffer;
do {
- /* reserve a byte for label length */
+ /* Reserve a byte for label length */
if (len <= 0)
return -ENOBUFS;
len--;
label_length = out;
out++;
- /* convert and copy a single label */
+ /* Convert and copy a single label. Note that
+ * dns_label_unescape() returns 0 when it hits the end
+ * of the domain name, which we rely on here to encode
+ * the trailing NUL byte. */
r = dns_label_unescape(&domain, (char *) out, len);
if (r < 0)
return r;
- /* fill label length, move forward */
+ /* Fill label length, move forward */
*label_length = r;
out += r;
len -= r;
+
} while (r != 0);
+ /* Verify the maximum size of the encoded name. The trailing
+ * dot + NUL byte account are included this time, hence
+ * compare against DNS_HOSTNAME_MAX + 2 (which is 255) this
+ * time. */
+ if (out - buffer > DNS_HOSTNAME_MAX + 2)
+ return -EINVAL;
+
return out - buffer;
}
diff --git a/src/test/test-dns-domain.c b/src/test/test-dns-domain.c
index 0762faa9a7..a1795b3be2 100644
--- a/src/test/test-dns-domain.c
+++ b/src/test/test-dns-domain.c
@@ -66,10 +66,36 @@ static void test_dns_name_to_wire_format_one(const char *what, const char *expec
}
static void test_dns_name_to_wire_format(void) {
- const char out0[] = { 0 };
- const char out1[] = { 3, 'f', 'o', 'o', 0 };
- const char out2[] = { 5, 'h', 'a', 'l', 'l', 'o', 3, 'f', 'o', 'o', 3, 'b', 'a', 'r', 0 };
- const char out3[] = { 4, ' ', 'f', 'o', 'o', 3, 'b', 'a', 'r', 0 };
+ static const char out0[] = { 0 };
+ static const char out1[] = { 3, 'f', 'o', 'o', 0 };
+ static const char out2[] = { 5, 'h', 'a', 'l', 'l', 'o', 3, 'f', 'o', 'o', 3, 'b', 'a', 'r', 0 };
+ static const char out3[] = { 4, ' ', 'f', 'o', 'o', 3, 'b', 'a', 'r', 0 };
+ static const char out4[] = { 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 9, 'a', '1', '2', '3', '4', '5', '6', '7', '8',
+ 3, 'a', '1', '2', 0 };
test_dns_name_to_wire_format_one("", out0, sizeof(out0), sizeof(out0));
@@ -81,6 +107,9 @@ static void test_dns_name_to_wire_format(void) {
test_dns_name_to_wire_format_one("hallo.foo..bar", NULL, 32, -EINVAL);
test_dns_name_to_wire_format_one("\\032foo.bar", out3, sizeof(out3), sizeof(out3));
+
+ test_dns_name_to_wire_format_one("a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a123", NULL, 500, -EINVAL);
+ test_dns_name_to_wire_format_one("a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12345678.a12", out4, sizeof(out4), sizeof(out4));
}
static void test_dns_label_unescape_suffix_one(const char *what, const char *expect1, const char *expect2, size_t buffer_sz, int ret1, int ret2) {