nwrap: rewrite linked-list datastructures to be properly separated.

The data structures were wrong:

- The nwrap_entdata structures reflects one line of the hosts
  file, with ip, fqdn and aliases.
  But they also had a linked list structure.

- Now the hash table was used to point each
  ip address, fqdn and alias name occurring in the hosts
  file to the list of lines (entdata structs) that contain
  this name/address.

The problem was that these list heads were pointing to the same
entdata structures, while the list should actually be individual
for each entity (ip, fqdn, alias). This lead to wrong assiciations
of lines to IP addresse and also endless loops in the list, when
one line was put into one list twice starting from two different
points.

This patch fixes this by lifting the linked list structure to
a layer nwrap_entlist above nwrap_entdata. The entlist
entries just contain pointers to the entdata, and hence
each line can be referenced independetly by several lists.

Signed-off-by: Michael Adam <obnox@samba.org>
Reviewed-by: Andreas Schneider <asn@samba.org>

diff --git a/lib/nss_wrapper/nss_wrapper.c b/lib/nss_wrapper/nss_wrapper.c
index bca1012b8f461459cb536056b2bda5f24a02aa73..6676b6abaf8bf017b34cb808517f5dccf09af4fc 100644 (file)
--- a/lib/nss_wrapper/nss_wrapper.c
+++ b/lib/nss_wrapper/nss_wrapper.c
@@ -758,9 +758,11 @@ struct nwrap_entdata {
        struct nwrap_vector nwrap_addrdata;
 
        ssize_t aliases_count;
+};
 
-       struct nwrap_entdata *ed_next;
-       struct nwrap_entdata *ed_tail;
+struct nwrap_entlist {
+       struct nwrap_entlist *next;
+       struct nwrap_entdata *ed;
 };
 
 struct nwrap_he {
@@ -2541,13 +2543,41 @@ static int nwrap_gr_copy_r(const struct group *src, struct group *dst,
        return 0;
 }
 
+static struct nwrap_entlist *nwrap_entlist_init(struct nwrap_entdata *ed)
+{
+       struct nwrap_entlist *el;
+
+       if (ed == NULL) {
+               NWRAP_LOG(NWRAP_LOG_ERROR,
+                         "entry is NULL, can't create list item");
+               return NULL;
+       }
+
+       el = (struct nwrap_entlist *)malloc(sizeof(struct nwrap_entlist));
+       if (el == NULL) {
+               NWRAP_LOG(NWRAP_LOG_ERROR, "malloc failed");
+               return NULL;
+       }
+
+       el->next = NULL;
+       el->ed = ed;
+
+       return el;
+}
+
 static bool nwrap_add_ai(char *const ip_addr, struct nwrap_entdata *const ed)
 {
-       ENTRY e = {
-               .key = ip_addr,
-               .data = (void *)ed,
-       };
+       ENTRY e;
        ENTRY *p;
+       struct nwrap_entlist *el;
+
+       el = nwrap_entlist_init(ed);
+       if (el == NULL) {
+               return false;
+       }
+
+       e.key = ip_addr;
+       e.data = el;
 
        p = hsearch(e, ENTER);
        if (p == NULL) {
@@ -2564,11 +2594,15 @@ static bool nwrap_add_hname_add_new(char *const h_name,
 {
        ENTRY e;
        ENTRY *p;
+       struct nwrap_entlist *el;
+
+       el = nwrap_entlist_init(ed);
+       if (el == NULL) {
+               return false;
+       }
 
        e.key = h_name;
-       e.data = (void *)ed;
-       ed->ed_tail = NULL;
-       ed->ed_next = NULL;
+       e.data = (void *)el;
 
        p = hsearch(e, ENTER);
        if (p == NULL) {
@@ -2580,17 +2614,30 @@ static bool nwrap_add_hname_add_new(char *const h_name,
 }
 
 static void nwrap_add_hname_add_to_existing(struct nwrap_entdata *const ed,
-                                           struct nwrap_entdata *const ed_dst)
+                                           struct nwrap_entlist *const el)
 {
-       if (ed_dst->ed_tail != NULL) {
-               ed_dst->ed_tail->ed_next = ed;
-               if (ed_dst->ed_tail != ed) {
-                       ed_dst->ed_tail = ed;
-                       ed->ed_next = NULL;
+       struct nwrap_entlist *cursor;
+       struct nwrap_entlist *el_new;
+
+       el_new = nwrap_entlist_init(ed);
+       if (el_new == NULL) {
+               return;
+       }
+
+       for (cursor = el; cursor->next != NULL; cursor = cursor->next)
+       {
+               if (cursor->ed == ed) {
+                       free(el_new);
+                       return;
                }
-       } else {
-               ed_dst->ed_tail = ed;
        }
+
+       if (cursor->ed == ed) {
+               free(el_new);
+               return;
+       }
+
+       cursor->next = el_new;
 }
 
 static bool nwrap_add_hname_alias(char *const h_name_a,
@@ -2610,11 +2657,11 @@ static bool nwrap_add_hname_alias(char *const h_name_a,
                NWRAP_LOG(NWRAP_LOG_DEBUG, "Name %s not found. Adding...", h_name_a);
                nwrap_add_hname_add_new(h_name_a, ed);
        } else {
-               struct nwrap_entdata *ed_dst = (struct nwrap_entdata *)p->data;
+               struct nwrap_entlist *el = (struct nwrap_entlist *)p->data;
 
                assert(p->data != NULL);
                NWRAP_LOG(NWRAP_LOG_DEBUG, "Name %s found. Add record to list.", h_name_a);
-               nwrap_add_hname_add_to_existing(ed, ed_dst);
+               nwrap_add_hname_add_to_existing(ed, el);
        }
 
        return true;
@@ -2637,16 +2684,12 @@ static bool nwrap_add_hname(struct nwrap_entdata *const ed)
        if (p == NULL) {
                NWRAP_LOG(NWRAP_LOG_DEBUG, "Name %s not found. Adding...", h_name);
                nwrap_add_hname_add_new(h_name, ed);
-
-               if (ed->ed_tail == NULL) {
-                       ed->ed_tail = ed;
-               }
        } else {
-               struct nwrap_entdata *ed_dst = (struct nwrap_entdata *)p->data;
+               struct nwrap_entlist *el = (struct nwrap_entlist *)p->data;
 
                assert(p->data != NULL);
                NWRAP_LOG(NWRAP_LOG_DEBUG, "Name %s found. Add record to list.", h_name);
-               nwrap_add_hname_add_to_existing(ed, ed_dst);
+               nwrap_add_hname_add_to_existing(ed, el);
        }
 
        if (ed->ht.h_aliases == NULL) {
@@ -3277,8 +3320,8 @@ static int nwrap_files_gethostbyname(const char *name, int af,
                                     struct hostent *result,
                                     struct nwrap_vector *addr_list)
 {
-       struct nwrap_entdata *ed_head;
-       struct nwrap_entdata *ed_cur;
+       struct nwrap_entlist *el_head;
+       struct nwrap_entlist *el_cur;
        struct hostent *he;
        char *h_name_lower;
        ENTRY e;
@@ -3327,9 +3370,9 @@ static int nwrap_files_gethostbyname(const char *name, int af,
        }
 
        /* Iterate through results */
-       ed_head = (struct nwrap_entdata *)e_p->data;
-       for (ed_cur = ed_head; ed_cur != NULL; ed_cur = ed_cur->ed_next) {
-               he = &(ed_cur->ht);
+       el_head = (struct nwrap_entlist *)e_p->data;
+       for (el_cur = el_head; el_cur != NULL; el_cur = el_cur->next) {
+               he = &(el_cur->ed->ht);
 
                /* Filter by address familiy if provided */
                if (af != AF_UNSPEC && he->h_addrtype != af) {
@@ -3351,7 +3394,7 @@ static int nwrap_files_gethostbyname(const char *name, int af,
                                  he->h_name);
                        he_found = true;
                }
-               nwrap_vector_merge(addr_list, &ed_cur->nwrap_addrdata);
+               nwrap_vector_merge(addr_list, &el_cur->ed->nwrap_addrdata);
                result->h_addr_list = nwrap_vector_head(addr_list);
        }
 
@@ -3437,8 +3480,8 @@ static struct addrinfo *nwrap_files_getaddrinfo(const char *name,
                                                const struct addrinfo *hints,
                                                struct addrinfo **ai_tail)
 {
-       struct nwrap_entdata *ed_head;
-       struct nwrap_entdata *ed_cur;
+       struct nwrap_entlist *el_head;
+       struct nwrap_entlist *el_cur;
        struct hostent *he;
        struct addrinfo *ai = NULL;
        struct addrinfo *ai_head = NULL;
@@ -3477,12 +3520,12 @@ static struct addrinfo *nwrap_files_getaddrinfo(const char *name,
        NWRAP_LOG(NWRAP_LOG_DEBUG, "Name: %s found.", h_name_lower);
        SAFE_FREE(h_name_lower);
 
-       ed_head = (struct nwrap_entdata *)e_p->data;
+       el_head = (struct nwrap_entlist *)e_p->data;
 
-       for (ed_cur = ed_head; ed_cur != NULL; ed_cur = ed_cur->ed_next) {
+       for (el_cur = el_head; el_cur != NULL; el_cur = el_cur->next) {
                int rc;
 
-               he = &(ed_cur->ht);
+               he = &(el_cur->ed->ht);
 
                if (hints->ai_family != AF_UNSPEC &&
                    he->h_addrtype != hints->ai_family) {