nss: rewrite nss responder so it uses cache_req

Given the size of the current nss responder it was quite impossible
to simply switch into using the cache_req interface, especially
because most of the code was duplication of cache lookups.

This patch completely rewrites the responder from scratch. The amount
of code was reduced to less than a half lines of code with no code duplication,
better documentation and better maintainability and readability.

All functionality should be intact.

*Code organization*
All protocol (parsing input message and send a reply) is placed
in nss_protocol.c. Functions that deals with creating a reply
packet are placed into their specific nss_protocol_$object.c files.

All supported commands are placed into nss_cmd.c. Functions that
deals with cache req are in nss_get_object.c and nss_enum.c.

*Code flow for non-enumeration*
An nss_getby_$input-type is called for each non-enumeration command.
This function parses the input message, creates a cache_req_data
structure and issues nss_get_object that calls cache_req. When
this request is done nss_getby_done make sure a reply is sent to
the client.

*Comments on enumeration*
I made some effort to make sure enumeration shares the same code
for users, groups, services and netgroups. Netgroups now uses
nss negative cache instead of implementing its own.

Resolves:
https://fedorahosted.org/sssd/ticket/3151

Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>

2 files changed, 8 insertions, 2 deletions

diff --git a/src/util/sss_ptr_hash.c b/src/util/sss_ptr_hash.c
index e34b9b2c1..4827e1e98 100644
--- a/src/util/sss_ptr_hash.c
+++ b/src/util/sss_ptr_hash.c
@@ -170,7 +170,7 @@ hash_table_t *sss_ptr_hash_create(TALLOC_CTX *mem_ctx,
     hash_table_t *table;
     errno_t ret;
 
-    data = talloc_zero(mem_ctx, struct sss_ptr_hash_delete_data);
+    data = talloc_zero(NULL, struct sss_ptr_hash_delete_data);
     if (data == NULL) {
         return NULL;
     }
@@ -178,7 +178,7 @@ hash_table_t *sss_ptr_hash_create(TALLOC_CTX *mem_ctx,
     data->callback = del_cb;
     data->pvt = del_cb_pvt;
 
-    ret = sss_hash_create_ex(NULL, 10, &table, 0, 0, 0, 0,
+    ret = sss_hash_create_ex(mem_ctx, 10, &table, 0, 0, 0, 0,
                              sss_ptr_hash_delete_cb, data);
     if (ret != EOK) {
         DEBUG(SSSDBG_CRIT_FAILURE, "Unable to create hash table [%d]: %s\n",
diff --git a/src/util/util_safealign.h b/src/util/util_safealign.h
index b1c9f8a0c..a2cd4dd0d 100644
--- a/src/util/util_safealign.h
+++ b/src/util/util_safealign.h
@@ -119,11 +119,17 @@ safealign_memcpy(void *dest, const void *src, size_t n, size_t *counter)
     safealign_memcpy(dest, src, sizeof(uint16_t), pctr); \
 } while(0)
 
+#define SAFEALIGN_SETMEM_STRING(dest, value, length, pctr) do { \
+    const char *CV_MACRO_val = (const char *)(value); \
+    safealign_memcpy(dest, CV_MACRO_val, sizeof(char) * length, pctr); \
+} while(0)
+
 /* Aliases for backward compatibility. */
 #define SAFEALIGN_SET_VALUE SAFEALIGN_SETMEM_VALUE
 #define SAFEALIGN_SET_INT64 SAFEALIGN_SETMEM_INT64
 #define SAFEALIGN_SET_UINT32 SAFEALIGN_SETMEM_UINT32
 #define SAFEALIGN_SET_INT32 SAFEALIGN_SETMEM_INT32
 #define SAFEALIGN_SET_UINT16 SAFEALIGN_SETMEM_UINT16
+#define SAFEALIGN_SET_STRING SAFEALIGN_SETMEM_STRING
 
 #endif /* _UTIL_SAFEALIGN_H */