ndr dns: Add simple parser

3 files changed, 214 insertions, 0 deletions

diff --git a/librpc/ndr/libndr.h b/librpc/ndr/libndr.h
index c110b76ae5..6bc96cada6 100644
--- a/librpc/ndr/libndr.h
+++ b/librpc/ndr/libndr.h
@@ -92,6 +92,7 @@ struct ndr_push {
 	struct ndr_token_list *relative_list;
 	struct ndr_token_list *relative_begin_list;
 	struct ndr_token_list *nbt_string_list;
+	struct ndr_token_list *dns_string_list;
 	struct ndr_token_list *full_ptr_list;
 
 	/* this is used to ensure we generate unique reference IDs */
diff --git a/librpc/ndr/ndr_dns.c b/librpc/ndr/ndr_dns.c
new file mode 100644
index 0000000000..18dde2bd1a
--- /dev/null
+++ b/librpc/ndr/ndr_dns.c
@@ -0,0 +1,210 @@
+/*
+   Unix SMB/CIFS implementation.
+
+   manipulate dns name structures
+
+   Copyright (C) 2010 Kai Blin  <kai@samba.org>
+
+   Heavily based on nbtname.c which is:
+
+   Copyright (C) Andrew Tridgell 2005
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/*
+  see rfc1002 for the detailed format of compressed names
+*/
+
+#include "includes.h"
+#include "librpc/gen_ndr/ndr_dns.h"
+#include "librpc/gen_ndr/ndr_misc.h"
+#include "system/locale.h"
+#include "lib/util/util_net.h"
+
+/* don't allow an unlimited number of name components */
+#define MAX_COMPONENTS 10
+
+/**
+  print a dns string
+*/
+_PUBLIC_ void ndr_print_dns_string(struct ndr_print *ndr, const char *name, const char *s)
+{
+	ndr_print_string(ndr, name, s);
+}
+
+/*
+  pull one component of a dns_string
+*/
+static enum ndr_err_code ndr_pull_component(struct ndr_pull *ndr,
+					    uint8_t **component,
+					    uint32_t *offset,
+					    uint32_t *max_offset)
+{
+	uint8_t len;
+	unsigned int loops = 0;
+	while (loops < 5) {
+		if (*offset >= ndr->data_size) {
+			return ndr_pull_error(ndr, NDR_ERR_STRING,
+					      "BAD DNS NAME component");
+		}
+		len = ndr->data[*offset];
+		if (len == 0) {
+			*offset += 1;
+			*max_offset = MAX(*max_offset, *offset);
+			*component = NULL;
+			return NDR_ERR_SUCCESS;
+		}
+		if ((len & 0xC0) == 0xC0) {
+			/* its a label pointer */
+			if (1 + *offset >= ndr->data_size) {
+				return ndr_pull_error(ndr, NDR_ERR_STRING,
+						      "BAD DNS NAME component");
+			}
+			*max_offset = MAX(*max_offset, *offset + 2);
+			*offset = ((len&0x3F)<<8) | ndr->data[1 + *offset];
+			*max_offset = MAX(*max_offset, *offset);
+			loops++;
+			continue;
+		}
+		if ((len & 0xC0) != 0) {
+			/* its a reserved length field */
+			return ndr_pull_error(ndr, NDR_ERR_STRING,
+					      "BAD DNS NAME component");
+		}
+		if (*offset + len + 2 > ndr->data_size) {
+			return ndr_pull_error(ndr, NDR_ERR_STRING,
+					      "BAD DNS NAME component");
+		}
+		*component = (uint8_t*)talloc_strndup(ndr, (const char *)&ndr->data[1 + *offset], len);
+		NDR_ERR_HAVE_NO_MEMORY(*component);
+		*offset += len + 1;
+		*max_offset = MAX(*max_offset, *offset);
+		return NDR_ERR_SUCCESS;
+	}
+
+	/* too many pointers */
+	return ndr_pull_error(ndr, NDR_ERR_STRING, "BAD DNS NAME component");
+}
+
+/**
+  pull a dns_string from the wire
+*/
+_PUBLIC_ enum ndr_err_code ndr_pull_dns_string(struct ndr_pull *ndr, int ndr_flags, const char **s)
+{
+	uint32_t offset = ndr->offset;
+	uint32_t max_offset = offset;
+	unsigned num_components;
+	char *name;
+
+	if (!(ndr_flags & NDR_SCALARS)) {
+		return NDR_ERR_SUCCESS;
+	}
+
+	name = NULL;
+
+	/* break up name into a list of components */
+	for (num_components=0;num_components<MAX_COMPONENTS;num_components++) {
+		uint8_t *component = NULL;
+		NDR_CHECK(ndr_pull_component(ndr, &component, &offset, &max_offset));
+		if (component == NULL) break;
+		if (name) {
+			name = talloc_asprintf_append_buffer(name, ".%s", component);
+			NDR_ERR_HAVE_NO_MEMORY(name);
+		} else {
+			name = (char *)component;
+		}
+	}
+	if (num_components == MAX_COMPONENTS) {
+		return ndr_pull_error(ndr, NDR_ERR_STRING,
+				      "BAD DNS NAME too many components");
+	}
+	if (num_components == 0) {
+		name = talloc_strdup(ndr, "");
+		NDR_ERR_HAVE_NO_MEMORY(name);
+	}
+
+	(*s) = name;
+	ndr->offset = max_offset;
+
+	return NDR_ERR_SUCCESS;
+}
+
+/**
+  push a dns string to the wire
+*/
+_PUBLIC_ enum ndr_err_code ndr_push_dns_string(struct ndr_push *ndr, int ndr_flags, const char *s)
+{
+	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;
+
+		/* see if we have pushed the remaing string allready,
+		 * if so we use a label pointer to this string
+		 */
+		ndr_err = ndr_token_retrieve_cmp_fn(&ndr->dns_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, ".");
+
+		/* we need to make sure the length fits into 6 bytes */
+		if (complen > 0x3F) {
+			return ndr_push_error(ndr, NDR_ERR_STRING,
+					      "component length %u[%08X] > 0x0000003F",
+					      (unsigned)complen, (unsigned)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 componemt + the rest of the string
+		 * so it can be reused later
+		 */
+		NDR_CHECK(ndr_token_store(ndr, &ndr->dns_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 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);
+}
diff --git a/librpc/ndr/ndr_dns.h b/librpc/ndr/ndr_dns.h
new file mode 100644
index 0000000000..d0b6ab36f3
--- /dev/null
+++ b/librpc/ndr/ndr_dns.h
@@ -0,0 +1,3 @@
+_PUBLIC_ void ndr_print_dns_string(struct ndr_print *ndr, const char *name, const char *s);
+_PUBLIC_ enum ndr_err_code ndr_pull_dns_string(struct ndr_pull *ndr, int ndr_flags, const char **s);
+_PUBLIC_ enum ndr_err_code ndr_push_dns_string(struct ndr_push *ndr, int ndr_flags, const char *s);