sdap: properly handle binary objectGuid attribute

Although in the initial processing SSSD treats the binary value right at
some point it mainly assumes that it is a string. Depending on the value
this might end up with the correct binary value stored in the cache but
in most cases there will be only a broken entry in the cache.

This patch converts the binary value into a string representation which
is described in [MS-DTYP] and stores the result in the cache.

Resolves https://fedorahosted.org/sssd/ticket/2588

Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>

2 files changed, 32 insertions, 0 deletions

diff --git a/src/util/string_utils.c b/src/util/string_utils.c
index a39b950e8..71b2a0920 100644
--- a/src/util/string_utils.c
+++ b/src/util/string_utils.c
@@ -83,3 +83,28 @@ char * sss_reverse_replace_space(TALLOC_CTX *mem_ctx,
 
     return replace_char(mem_ctx, orig_name, subst, ' ');
 }
+
+errno_t guid_blob_to_string_buf(const uint8_t *blob, char *str_buf,
+                                size_t buf_size)
+{
+    int ret;
+
+    if (blob == NULL || str_buf == NULL || buf_size < GUID_STR_BUF_SIZE) {
+        DEBUG(SSSDBG_CRIT_FAILURE, "Buffer too small.\n");
+        return EINVAL;
+    }
+
+    ret = snprintf(str_buf, buf_size,
+         "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
+         blob[3], blob[2], blob[1], blob[0],
+         blob[5], blob[4],
+         blob[7], blob[6],
+         blob[8], blob[9],
+         blob[10], blob[11],blob[12], blob[13],blob[14], blob[15]);;
+    if (ret != (GUID_STR_BUF_SIZE -1)) {
+        DEBUG(SSSDBG_CRIT_FAILURE, "snprintf failed.\n");
+        return EIO;
+    }
+
+    return EOK;
+}
diff --git a/src/util/util.h b/src/util/util.h
index 829cf567a..704e10dc6 100644
--- a/src/util/util.h
+++ b/src/util/util.h
@@ -630,6 +630,13 @@ char * sss_reverse_replace_space(TALLOC_CTX *mem_ctx,
                                  const char *orig_name,
                                  const char replace_char);
 
+#define GUID_BIN_LENGTH 16
+/* 16 2-digit hex values + 4 dashes + terminating 0 */
+#define GUID_STR_BUF_SIZE (2 * GUID_BIN_LENGTH + 4 + 1)
+
+errno_t guid_blob_to_string_buf(const uint8_t *blob, char *str_buf,
+                                size_t buf_size);
+
 /* from become_user.c */
 errno_t become_user(uid_t uid, gid_t gid);
 struct sss_creds;