1 files changed, 113 insertions, 0 deletions
diff --git a/libglouglou/libggnet_dns.c b/libglouglou/libggnet_dns.c
new file mode 100644
index 0000000..9685cde
--- /dev/null
+++ b/libglouglou/libggnet_dns.c
@@ -0,0 +1,113 @@
+#include <stdlib.h>
+#include <string.h>
+
+#include "libggnet_dns.h"
+
+/*
+ * For dns with libevent, see
+ * http://www.wangafu.net/~nickm/libevent-2.0/doxygen/html/dns_8h.html
+ * http://www.wangafu.net/~nickm/libevent-book/Ref9_dns.html
+ * spike/evdns_chrooted.c
+ * spike/evdns.c
+ */
+
+static void _cb_evdns_reverse(int, char, int, int, void *, void *);
+
+struct req_reverse {
+  LIST_ENTRY(req_reverse) entry;
+  struct ggnet_dns *ggdns;
+  struct evdns_request *ereq;
+  struct in_addr ip;
+  void (*cb_usr)(struct in_addr *, char *, void *);
+  void  *data;
+};
+
+struct ggnet_dns *
+ggnet_dns_new(struct event_base *ev_base)
+{
+  struct ggnet_dns *dns = NULL;
+
+  dns = calloc(1, sizeof(struct ggnet_dns));
+  if (!dns) {
+    printf("could not allocate ggnet_dns\n");
+    exit(1);
+  }
+  dns->ev_base = ev_base;
+  dns->evdns_base = evdns_base_new(ev_base, 1);
+  if (!dns->evdns_base)
+    goto err;
+  return dns;
+
+err:
+  if (dns)
+    free(dns);
+  return NULL;
+}
+
+void
+ggnet_dns_free(struct ggnet_dns *dns)
+{
+  evdns_base_free(dns->evdns_base, 1);
+  free(dns);
+}
+
+int
+ggnet_dns_reverse(struct ggnet_dns *dns,
+                  struct in_addr *ip,
+                    void (*cb_usr)(struct in_addr *, char *, void *),
+                    void *data)
+{
+  struct evutil_addrinfo hints;
+  struct req_reverse *req;
+  struct evdns_request *ereq;
+
+  memset(&hints, 0, sizeof(hints));
+  hints.ai_family = AF_UNSPEC;
+  hints.ai_flags = EVUTIL_AI_CANONNAME;
+  hints.ai_socktype = SOCK_STREAM;
+  hints.ai_protocol = IPPROTO_TCP;
+
+  req = malloc(sizeof(struct req_reverse));
+  if (!req) {
+    printf("could not allocate req_reverse\n");
+    exit(1);
+  }
+  req->ggdns = dns;
+  memcpy(&req->ip, ip, sizeof(struct in_addr));
+  req->cb_usr = cb_usr;
+  req->data = data;
+
+  LIST_INSERT_HEAD(&dns->req_reverse_list, req, entry);
+  dns->req_reverse_pending++;
+  ereq = evdns_base_resolve_reverse(dns->evdns_base, ip, 0,
+                                    _cb_evdns_reverse, req);
+  if (ereq == NULL) {
+    printf("libggnet_dns WARNING: dns request for %d returned immediately\n",
+           ip->s_addr);
+    /* remove req from list and free it happened in the callback. */
+    return 0;
+  }
+  req->ereq = ereq;
+
+  return 1;
+}
+
+static void
+_cb_evdns_reverse(int result, char type, int count,
+                  int ttl, void *addresses, void *arg)
+{
+  struct req_reverse *req;
+
+  req = arg;
+  if (type != DNS_PTR) {
+    printf("libggnet_dns WARNING: dns reverse for %d received non DNS_PTR\n",
+           req->ip.s_addr);
+    goto free;
+  }
+  req->cb_usr(&req->ip, addresses, req->data);
+
+free:
+  LIST_REMOVE(req, entry);
+  req->ggdns->req_reverse_pending--;
+  free(req);
+}