1 files changed, 134 insertions, 0 deletions
diff --git a/librpc/ndr/ndr_dns_utils.c b/librpc/ndr/ndr_dns_utils.c
new file mode 100644
index 00000000000..325d9c68bea
--- /dev/null
+++ b/librpc/ndr/ndr_dns_utils.c
@@ -0,0 +1,134 @@
+#include "includes.h"
+#include "../librpc/ndr/libndr.h"
+#include "ndr_dns_utils.h"
+
+
+/**
+  push a dns/nbt string list to the wire
+*/
+enum ndr_err_code ndr_push_dns_string_list(struct ndr_push *ndr,
+					   struct ndr_token_list *string_list,
+					   int ndr_flags,
+					   const char *s,
+					   bool is_nbt)
+{
+	const char *start = s;
+	bool use_compression;
+	size_t max_length;
+	if (is_nbt) {
+		use_compression = true;
+		/*
+		 * Max length is longer in NBT/Wins, because Windows counts
+		 * the semi-decompressed size of the netbios name (16 bytes)
+		 * rather than the wire size of 32, which is what you'd expect
+		 * if it followed RFC1002 (it uses the short form in
+		 * [MS-WINSRA]). In other words the maximum size of the
+		 * "scope" is 237, not 221.
+		 *
+		 * We make the size limit slightly larger than 255 + 16,
+		 * because the 237 scope limit is already enforced in the
+		 * winsserver code with a specific return value; bailing out
+		 * here would muck with that.
+		 */
+		max_length = 274;
+	} else {
+		use_compression = !(ndr->flags & LIBNDR_FLAG_NO_COMPRESSION);
+		max_length = 255;
+	}
+
+	if (!(ndr_flags & NDR_SCALARS)) {
+		return NDR_ERR_SUCCESS;
+	}
+
+	while (s && *s) {
+		enum ndr_err_code ndr_err;
+		char *compname;
+		size_t complen;
+		uint32_t offset;
+
+		if (use_compression) {
+			/* see if we have pushed the remaining string already,
+			 * if so we use a label pointer to this string
+			 */
+			ndr_err = ndr_token_retrieve_cmp_fn(string_list, s,
+							    &offset,
+							    (comparison_fn_t)strcmp,
+							    false);
+			if (NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+				uint8_t b[2];
+
+				if (offset > 0x3FFF) {
+					return ndr_push_error(ndr, NDR_ERR_STRING,
+							      "offset for dns string " \
+							      "label pointer " \
+							      "%u[%08X] > 0x00003FFF",
+							      offset, offset);
+				}
+
+				b[0] = 0xC0 | (offset>>8);
+				b[1] = (offset & 0xFF);
+
+				return ndr_push_bytes(ndr, b, 2);
+			}
+		}
+
+		complen = strcspn(s, ".");
+
+		/* the length must fit into 6 bits (i.e. <= 63) */
+		if (complen > 0x3F) {
+			return ndr_push_error(ndr, NDR_ERR_STRING,
+					      "component length %u[%08X] > " \
+					      "0x0000003F",
+					      (unsigned)complen,
+					      (unsigned)complen);
+		}
+
+		if (complen == 0 && s[complen] == '.') {
+			return ndr_push_error(ndr, NDR_ERR_STRING,
+					      "component length is 0 "
+					      "(consecutive dots)");
+		}
+
+		if (is_nbt && s[complen] == '.' && s[complen + 1] == '\0') {
+			/* nbt names are sometimes usernames, and we need to
+			 * keep a trailing dot to ensure it is byte-identical,
+			 * (not just semantically identical given DNS
+			 * semantics). */
+			complen++;
+		}
+
+		compname = talloc_asprintf(ndr, "%c%*.*s",
+						(unsigned char)complen,
+						(unsigned char)complen,
+						(unsigned char)complen, s);
+		NDR_ERR_HAVE_NO_MEMORY(compname);
+
+		/* remember the current component + the rest of the string
+		 * so it can be reused later
+		 */
+		if (use_compression) {
+			NDR_CHECK(ndr_token_store(ndr, string_list, s,
+						  ndr->offset));
+		}
+
+		/* push just this component into the blob */
+		NDR_CHECK(ndr_push_bytes(ndr, (const uint8_t *)compname,
+					 complen+1));
+		talloc_free(compname);
+
+		s += complen;
+		if (*s == '.') {
+			s++;
+		}
+		if (s - start > max_length) {
+			return ndr_push_error(ndr, NDR_ERR_STRING,
+					      "name > %zu character long",
+					      max_length);
+		}
+	}
+
+	/* if we reach the end of the string and have pushed the last component
+	 * without using a label pointer, we need to terminate the string
+	 */
+	return ndr_push_bytes(ndr, (const uint8_t *)"", 1);
+}