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authorStefan Metzmacher <metze@samba.org>2010-09-23 18:10:28 +0200
committerStefan Metzmacher <metze@samba.org>2010-09-26 06:45:39 +0200
commit182a69c5be7706fbb542694c7be51d499b61c98d (patch)
tree16e0d4c7b1bd34ba5a11915ffc8565d3d56bed82 /lib/util
parente628bf1081929684d888353101296cc17d9f3ae4 (diff)
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lib/util/asn1: add asn1_peek_tag_needed_size() and asn1_peek_full_tag()
We need a way to ask for the length of a tag without having the full buffer yet. metze
Diffstat (limited to 'lib/util')
-rw-r--r--lib/util/asn1.c83
-rw-r--r--lib/util/asn1.h2
2 files changed, 85 insertions, 0 deletions
diff --git a/lib/util/asn1.c b/lib/util/asn1.c
index 8f30cfe2c6..c4923343e2 100644
--- a/lib/util/asn1.c
+++ b/lib/util/asn1.c
@@ -489,6 +489,65 @@ bool asn1_peek_tag(struct asn1_data *data, uint8_t tag)
return (b == tag);
}
+/*
+ * just get the needed size the tag would consume
+ */
+bool asn1_peek_tag_needed_size(struct asn1_data *data, uint8_t tag, size_t *size)
+{
+ off_t start_ofs = data->ofs;
+ uint8_t b;
+ size_t taglen = 0;
+
+ if (data->has_error) {
+ return false;
+ }
+
+ if (!asn1_read_uint8(data, &b)) {
+ data->ofs = start_ofs;
+ data->has_error = false;
+ return false;
+ }
+
+ if (b != tag) {
+ data->ofs = start_ofs;
+ data->has_error = false;
+ return false;
+ }
+
+ if (!asn1_read_uint8(data, &b)) {
+ data->ofs = start_ofs;
+ data->has_error = false;
+ return false;
+ }
+
+ if (b & 0x80) {
+ int n = b & 0x7f;
+ if (!asn1_read_uint8(data, &b)) {
+ data->ofs = start_ofs;
+ data->has_error = false;
+ return false;
+ }
+ taglen = b;
+ while (n > 1) {
+ if (!asn1_read_uint8(data, &b)) {
+ data->ofs = start_ofs;
+ data->has_error = false;
+ return false;
+ }
+ taglen = (taglen << 8) | b;
+ n--;
+ }
+ } else {
+ taglen = b;
+ }
+
+ *size = (data->ofs - start_ofs) + taglen;
+
+ data->ofs = start_ofs;
+ data->has_error = false;
+ return true;
+}
+
/* start reading a nested asn1 structure */
bool asn1_start_tag(struct asn1_data *data, uint8_t tag)
{
@@ -943,6 +1002,30 @@ NTSTATUS asn1_full_tag(DATA_BLOB blob, uint8_t tag, size_t *packet_size)
if (size > blob.length) {
return STATUS_MORE_ENTRIES;
+ }
+
+ *packet_size = size;
+ return NT_STATUS_OK;
+}
+
+NTSTATUS asn1_peek_full_tag(DATA_BLOB blob, uint8_t tag, size_t *packet_size)
+{
+ struct asn1_data asn1;
+ uint32_t size;
+ bool ok;
+
+ ZERO_STRUCT(asn1);
+ asn1.data = blob.data;
+ asn1.length = blob.length;
+
+ ok = asn1_peek_tag_needed_size(&asn1, tag, &size);
+ if (!ok) {
+ return STATUS_MORE_ENTRIES;
+ }
+
+ if (size > blob.length) {
+ *packet_size = size;
+ return STATUS_MORE_ENTRIES;
}
*packet_size = size;
diff --git a/lib/util/asn1.h b/lib/util/asn1.h
index ded3244bed..266a9a386b 100644
--- a/lib/util/asn1.h
+++ b/lib/util/asn1.h
@@ -79,6 +79,7 @@ bool asn1_peek(struct asn1_data *data, void *p, int len);
bool asn1_read(struct asn1_data *data, void *p, int len);
bool asn1_read_uint8(struct asn1_data *data, uint8_t *v);
bool asn1_peek_uint8(struct asn1_data *data, uint8_t *v);
+bool asn1_peek_tag_needed_size(struct asn1_data *data, uint8_t tag, size_t *size);
bool asn1_peek_tag(struct asn1_data *data, uint8_t tag);
bool asn1_start_tag(struct asn1_data *data, uint8_t tag);
bool asn1_end_tag(struct asn1_data *data);
@@ -100,5 +101,6 @@ bool asn1_write_enumerated(struct asn1_data *data, uint8_t v);
bool asn1_blob(const struct asn1_data *asn1, DATA_BLOB *blob);
void asn1_load_nocopy(struct asn1_data *data, uint8_t *buf, size_t len);
NTSTATUS asn1_full_tag(DATA_BLOB blob, uint8_t tag, size_t *packet_size);
+NTSTATUS asn1_peek_full_tag(DATA_BLOB blob, uint8_t tag, size_t *packet_size);
#endif /* _ASN_1_H */