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grub2/grub-2.00-Issue-separate-DNS-queries-for-ipv4-and-ipv6.patch
Peter Jones f2e5630d7d Various ppc updates.
2012-10-18 13:47:39 -04:00

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From 3e00d82827f80461f9fe6da37acd84235c08e5a5 Mon Sep 17 00:00:00 2001
From: Gustavo Luiz Duarte <gustavold@linux.vnet.ibm.com>
Date: Fri, 28 Sep 2012 19:42:07 -0400
Subject: [PATCH] Issue separate DNS queries for ipv4 and ipv6
Adding multiple questions on a single DNS query is not supportted by
most DNS servers. This patch issues two separate DNS queries
sequentially for ipv4 and then for ipv6.
There are 4 possible config options:
DNS_OPTION_IPV4: issue only one ipv4 query
DNS_OPTION_IPV6: issue only one ipv6 query
DNS_OPTION_PREFER_IPV4: issue the ipv4 query first and fallback to ipv6
DNS_OPTION_PREFER_IPV6: issue the ipv6 query first and fallback to ipv4
However, there is no code yet to set such config option. The default is
DNS_OPTION_PREFER_IPV4.
Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=860829
---
grub-core/net/dns.c | 99 ++++++++++++++++++++++++++++++++++++-----------------
include/grub/net.h | 9 +++++
2 files changed, 76 insertions(+), 32 deletions(-)
diff --git a/grub-core/net/dns.c b/grub-core/net/dns.c
index 3381ea7..725725c 100644
--- a/grub-core/net/dns.c
+++ b/grub-core/net/dns.c
@@ -34,6 +34,14 @@ struct dns_cache_element
#define DNS_CACHE_SIZE 1021
#define DNS_HASH_BASE 423
+typedef enum grub_dns_qtype_id
+ {
+ GRUB_DNS_QTYPE_A = 1,
+ GRUB_DNS_QTYPE_AAAA = 28
+ } grub_dns_qtype_id_t;
+
+static grub_dns_option_t dns_type_option = DNS_OPTION_PREFER_IPV4;
+
static struct dns_cache_element dns_cache[DNS_CACHE_SIZE];
static struct grub_net_network_level_address *dns_servers;
static grub_size_t dns_nservers, dns_servers_alloc;
@@ -410,13 +418,13 @@ recv_hook (grub_net_udp_socket_t sock __attribute__ ((unused)),
return GRUB_ERR_NONE;
}
-grub_err_t
-grub_net_dns_lookup (const char *name,
+static grub_err_t
+grub_net_dns_lookup_qtype (const char *name,
const struct grub_net_network_level_address *servers,
grub_size_t n_servers,
grub_size_t *naddresses,
struct grub_net_network_level_address **addresses,
- int cache)
+ int cache, grub_dns_qtype_id_t qtype)
{
grub_size_t send_servers = 0;
grub_size_t i, j;
@@ -471,8 +479,7 @@ grub_net_dns_lookup (const char *name,
+ GRUB_NET_MAX_LINK_HEADER_SIZE
+ GRUB_NET_UDP_HEADER_SIZE
+ sizeof (struct dns_header)
- + grub_strlen (name) + 2 + 4
- + 2 + 4);
+ + grub_strlen (name) + 2 + 4);
if (!nb)
{
grub_free (data.name);
@@ -482,7 +489,7 @@ grub_net_dns_lookup (const char *name,
+ GRUB_NET_MAX_LINK_HEADER_SIZE
+ GRUB_NET_UDP_HEADER_SIZE);
grub_netbuff_put (nb, sizeof (struct dns_header)
- + grub_strlen (name) + 2 + 4 + 2 + 4);
+ + grub_strlen (name) + 2 + 4);
head = (struct dns_header *) nb->data;
optr = (grub_uint8_t *) (head + 1);
for (iptr = name; *iptr; )
@@ -509,18 +516,7 @@ grub_net_dns_lookup (const char *name,
/* Type: A. */
*optr++ = 0;
- *optr++ = 1;
-
- /* Class. */
- *optr++ = 0;
- *optr++ = 1;
-
- /* Compressed name. */
- *optr++ = 0xc0;
- *optr++ = 0x0c;
- /* Type: AAAA. */
- *optr++ = 0;
- *optr++ = 28;
+ *optr++ = qtype;
/* Class. */
*optr++ = 0;
@@ -529,7 +525,7 @@ grub_net_dns_lookup (const char *name,
head->id = data.id;
head->flags = FLAGS_RD;
head->ra_z_r_code = 0;
- head->qdcount = grub_cpu_to_be16_compile_time (2);
+ head->qdcount = grub_cpu_to_be16_compile_time (1);
head->ancount = grub_cpu_to_be16_compile_time (0);
head->nscount = grub_cpu_to_be16_compile_time (0);
head->arcount = grub_cpu_to_be16_compile_time (0);
@@ -587,16 +583,47 @@ grub_net_dns_lookup (const char *name,
if (*data.naddresses)
return GRUB_ERR_NONE;
if (data.dns_err)
- return grub_error (GRUB_ERR_NET_NO_DOMAIN,
- N_("no DNS record found"));
-
+ {
+ grub_dprintf ("dns", "%s. QTYPE: %u QNAME: %s\n",
+ N_("no DNS record found"), qtype, name);
+ return GRUB_ERR_NET_NO_DOMAIN;
+ }
if (err)
{
grub_errno = err;
return err;
}
- return grub_error (GRUB_ERR_TIMEOUT,
- N_("no DNS reply received"));
+ grub_dprintf ("dns", "%s. QTYPE: %u QNAME: %s\n",
+ N_("no DNS reply received"), qtype, name);
+ return GRUB_ERR_TIMEOUT;
+}
+
+grub_err_t
+grub_net_dns_lookup (const char *name,
+ const struct grub_net_network_level_address *servers,
+ grub_size_t n_servers,
+ grub_size_t *naddresses,
+ struct grub_net_network_level_address **addresses,
+ int cache)
+{
+ if (dns_type_option == DNS_OPTION_IPV6 || dns_type_option == DNS_OPTION_PREFER_IPV6)
+ grub_net_dns_lookup_qtype (name, servers, n_servers, naddresses,
+ addresses, cache, GRUB_DNS_QTYPE_AAAA);
+ else
+ grub_net_dns_lookup_qtype (name, servers, n_servers, naddresses,
+ addresses, cache, GRUB_DNS_QTYPE_A);
+ if (!*naddresses)
+ {
+ if (dns_type_option == DNS_OPTION_PREFER_IPV4)
+ grub_net_dns_lookup_qtype (name, servers, n_servers, naddresses,
+ addresses, cache, GRUB_DNS_QTYPE_AAAA);
+ else if (dns_type_option == DNS_OPTION_PREFER_IPV6)
+ grub_net_dns_lookup_qtype (name, servers, n_servers, naddresses,
+ addresses, cache, GRUB_DNS_QTYPE_A);
+ }
+ if (!*naddresses)
+ return GRUB_ERR_NET_NO_DOMAIN;
+ return GRUB_ERR_NONE;
}
static grub_err_t
@@ -604,22 +631,28 @@ grub_cmd_nslookup (struct grub_command *cmd __attribute__ ((unused)),
int argc, char **args)
{
grub_err_t err;
- grub_size_t naddresses, i;
+ struct grub_net_network_level_address cmd_server;
+ struct grub_net_network_level_address *servers;
+ grub_size_t nservers, i, naddresses = 0;
struct grub_net_network_level_address *addresses = 0;
if (argc != 2 && argc != 1)
return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("two arguments expected"));
if (argc == 2)
{
- struct grub_net_network_level_address server;
- err = grub_net_resolve_address (args[1], &server);
+ err = grub_net_resolve_address (args[1], &cmd_server);
if (err)
return err;
- err = grub_net_dns_lookup (args[0], &server, 1, &naddresses,
- &addresses, 0);
+ servers = &cmd_server;
+ nservers = 1;
}
else
- err = grub_net_dns_lookup (args[0], dns_servers, dns_nservers, &naddresses,
- &addresses, 0);
+ {
+ servers = dns_servers;
+ nservers = dns_nservers;
+ }
+
+ grub_net_dns_lookup (args[0], servers, nservers, &naddresses,
+ &addresses, 0);
for (i = 0; i < naddresses; i++)
{
@@ -628,7 +661,9 @@ grub_cmd_nslookup (struct grub_command *cmd __attribute__ ((unused)),
grub_printf ("%s\n", buf);
}
grub_free (addresses);
- return GRUB_ERR_NONE;
+ if (naddresses)
+ return GRUB_ERR_NONE;
+ return grub_error (GRUB_ERR_NET_NO_DOMAIN, N_("no DNS record found"));
}
static grub_err_t
diff --git a/include/grub/net.h b/include/grub/net.h
index 3877451..a7e5b2c 100644
--- a/include/grub/net.h
+++ b/include/grub/net.h
@@ -505,6 +505,15 @@ grub_err_t
grub_net_link_layer_resolve (struct grub_net_network_level_interface *inf,
const grub_net_network_level_address_t *proto_addr,
grub_net_link_level_address_t *hw_addr);
+
+typedef enum
+ {
+ DNS_OPTION_IPV4,
+ DNS_OPTION_IPV6,
+ DNS_OPTION_PREFER_IPV4,
+ DNS_OPTION_PREFER_IPV6
+ } grub_dns_option_t;
+
grub_err_t
grub_net_dns_lookup (const char *name,
const struct grub_net_network_level_address *servers,
--
1.7.11.4
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