Add initial support for hostname lookup via resolver

diff --git a/gresolv/gresolv.c b/gresolv/gresolv.c
index d1aa8d2..8256b0b 100644 (file)
--- a/gresolv/gresolv.c
+++ b/gresolv/gresolv.c
@@ -25,6 +25,7 @@
 
 #include <errno.h>
 #include <unistd.h>
+#include <stdarg.h>
 #include <string.h>
 #include <resolv.h>
 #include <sys/socket.h>
@@ -34,11 +35,14 @@
 #include "gresolv.h"
 
 struct resolv_nameserver {
+       GResolv *resolv;
+
        char *address;
        uint16_t port;
        unsigned long flags;
 
        GIOChannel *udp_channel;
+       guint udp_watch;
 };
 
 struct _GResolv {
@@ -51,11 +55,30 @@ struct _GResolv {
        gpointer debug_data;
 };
 
+static inline void debug(GResolv *resolv, const char *format, ...)
+{
+       char str[256];
+       va_list ap;
+
+       if (resolv->debug_func == NULL)
+               return;
+
+       va_start(ap, format);
+
+       if (vsnprintf(str, sizeof(str), format, ap) > 0)
+               resolv->debug_func(str, resolv->debug_data);
+
+       va_end(ap);
+}
+
 static void free_nameserver(struct resolv_nameserver *nameserver)
 {
        if (nameserver == NULL)
                return;
 
+       if (nameserver->udp_watch > 0)
+               g_source_remove(nameserver->udp_watch);
+
        if (nameserver->udp_channel != NULL)
                g_io_channel_unref(nameserver->udp_channel);
 
@@ -75,6 +98,89 @@ static void flush_nameservers(GResolv *resolv)
        resolv->nameserver_list = NULL;
 }
 
+static int send_query(GResolv *resolv, const unsigned char *buf, int len)
+{
+       GList *list;
+
+       if (resolv->nameserver_list == NULL)
+               return -ENOENT;
+
+       for (list = g_list_first(resolv->nameserver_list);
+                                       list; list = g_list_next(list)) {
+               struct resolv_nameserver *nameserver = list->data;
+               int sk, sent;
+
+               if (nameserver->udp_channel == NULL)
+                       continue;
+
+               sk = g_io_channel_unix_get_fd(nameserver->udp_channel);
+
+               sent = send(sk, buf, len, 0);
+       }
+
+       return 0;
+}
+
+static void parse_response(struct resolv_nameserver *nameserver,
+                                       const unsigned char *buf, int len)
+{
+       GResolv *resolv = nameserver->resolv;
+       ns_msg msg;
+       ns_rr rr;
+       int i, rcode;
+
+       debug(resolv, "response from %s", nameserver->address);
+
+       ns_initparse(buf, len, &msg);
+
+       rcode = ns_msg_getflag(msg, ns_f_rcode);
+
+       debug(resolv, "msg id: 0x%04x rcode: %d count: %d",
+                       ns_msg_id(msg), rcode, ns_msg_count(msg, ns_s_an));
+
+       for (i = 0; i < ns_msg_count(msg, ns_s_an); i++) {
+               char result[100];
+
+               ns_parserr(&msg, ns_s_an, i, &rr);
+
+               if (ns_rr_class(rr) != ns_c_in)
+                       continue;
+
+               if (ns_rr_type(rr) != ns_t_a)
+                       continue;
+
+               if (ns_rr_rdlen(rr) != NS_INADDRSZ)
+                       continue;
+
+               inet_ntop(AF_INET, ns_rr_rdata(rr), result, sizeof(result));
+
+               debug(resolv, "result: %s", result);
+       }
+}
+
+static gboolean received_udp_data(GIOChannel *channel, GIOCondition cond,
+                                                       gpointer user_data)
+{
+       struct resolv_nameserver *nameserver = user_data;
+       unsigned char buf[4096];
+       int sk, len;
+
+       if (cond & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
+               nameserver->udp_watch = 0;
+               return FALSE;
+       }
+
+       sk = g_io_channel_unix_get_fd(nameserver->udp_channel);
+
+       len = recv(sk, buf, sizeof(buf), 0);
+       if (len < 12)
+               return TRUE;
+
+       parse_response(nameserver, buf, len);
+
+       return TRUE;
+}
+
 static int connect_udp_channel(struct resolv_nameserver *nameserver)
 {
        struct sockaddr_in sin;
@@ -102,6 +208,10 @@ static int connect_udp_channel(struct resolv_nameserver *nameserver)
 
        g_io_channel_set_close_on_unref(nameserver->udp_channel, TRUE);
 
+       nameserver->udp_watch = g_io_add_watch(nameserver->udp_channel,
+                                               G_IO_IN, received_udp_data,
+                                                               nameserver);
+
        return 0;
 }
 
@@ -178,9 +288,13 @@ int g_resolv_add_nameserver(GResolv *resolv, const char *address,
                return -EIO;
        }
 
+       nameserver->resolv = resolv;
+
        resolv->nameserver_list = g_list_append(resolv->nameserver_list,
                                                                nameserver);
 
+       debug(resolv, "setting nameserver %s", address);
+
        return 0;
 }
 
@@ -191,3 +305,19 @@ void g_resolv_flush_nameservers(GResolv *resolv)
 
        flush_nameservers(resolv);
 }
+
+int g_resolv_lookup_hostname(GResolv *resolv, const char *hostname)
+{
+       unsigned char buf[4096];
+       int len;
+
+       debug(resolv, "lookup hostname %s", hostname);
+
+       len = res_mkquery(ns_o_query, hostname, ns_c_in, ns_t_a,
+                                       NULL, 0, NULL, buf, sizeof(buf));
+
+       if (send_query(resolv, buf, len) < 0)
+               return -EIO;
+
+       return 0;
+}

diff --git a/gresolv/gresolv.h b/gresolv/gresolv.h
index 40b4972..baafd35 100644 (file)
--- a/gresolv/gresolv.h
+++ b/gresolv/gresolv.h
@@ -48,6 +48,8 @@ int g_resolv_add_nameserver(GResolv *resolv, const char *address,
                                        uint16_t port, unsigned long flags);
 void g_resolv_flush_nameservers(GResolv *resolv);
 
+int g_resolv_lookup_hostname(GResolv *resolv, const char *hostname);
+
 #ifdef __cplusplus
 }
 #endif