backends: use nsswitch getaddrinfo when available

This API originates from a proposal from Alexandre Oliva
<aoliva@redhat.com>. The nss netresolve backend will be updated
with the proposal.

diff --git a/backends/nss.c b/backends/nss.c
index dc8e83edbd29f7a77b84ee62303031d2f1f94f66..768fa443157eb447f04d49f5fd10ac3d1fee863f 100644 (file)
--- a/backends/nss.c
+++ b/backends/nss.c
@@ -76,6 +76,15 @@ struct priv_nss {
                const char *trimdomain[4];
                unsigned int flags;
        } *res_hconf;
+       /* getaddrinfo:
+        *
+        * A getaddrinfo based API encorporating capabilities of all
+        * gethostbyname*_r APIs and more.
+        */
+       int (*getaddrinfo)(const char *nodename, const char *servname,
+               const struct addrinfo *hints,
+               struct addrinfo **res,
+               int32_t *ttlp);
 };
 
 static int
@@ -156,6 +165,7 @@ initialize(struct priv_nss *priv, netresolve_query_t query, char **settings)
        try_symbol_pattern(query, priv, (void *) &priv->gethostbyname3_r, "_nss_%s_gethostbyname3_r", "gethostbyname3");
        try_symbol_pattern(query, priv, (void *) &priv->gethostbyname4_r, "_nss_%s_gethostbyname4_r", "gethostbyname4");
        try_symbol_pattern(query, priv, (void *) &priv->res_hconf, "_res_hconf", "gethostbyname4");
+       try_symbol_pattern(query, priv, (void *) &priv->getaddrinfo, "_nss_%s_getaddrinfo", "getaddrinfo");
 
        free(priv->name);
        priv->name = NULL;
@@ -183,7 +193,18 @@ start(netresolve_query_t query, char **settings)
                return;
        }
 
-       if (priv.gethostbyname4_r && family == AF_UNSPEC) {
+       if (priv.getaddrinfo) {
+               const char *service = netresolve_backend_get_servname(query);
+               struct addrinfo hints = netresolve_backend_get_addrinfo_hints(query);
+               int status;
+               struct addrinfo *result;
+               int32_t ttl;
+
+               status = DL_CALL_FCT(priv.getaddrinfo, (node, service, &hints, &result, &ttl));
+               netresolve_backend_apply_addrinfo(query, status, result, ttl);
+               if (status == 0)
+                       freeaddrinfo(result);
+       } else if (priv.gethostbyname4_r && family == AF_UNSPEC) {
                char buffer[SIZE] = { 0 };
                enum nss_status status;
                struct gaih_addrtuple *result;