Issue-separate-DNS-queries-for-ipv4-and-ipv6.patch

   1 From 3e00d82827f80461f9fe6da37acd84235c08e5a5 Mon Sep 17 00:00:00 2001
   2 From: Gustavo Luiz Duarte <gustavold@linux.vnet.ibm.com>
   3 Date: Fri, 28 Sep 2012 19:42:07 -0400
   4 Subject: [PATCH] Issue separate DNS queries for ipv4 and ipv6
   5
   6 Adding multiple questions on a single DNS query is not supportted by
   7 most DNS servers. This patch issues two separate DNS queries
   8 sequentially for ipv4 and then for ipv6.
   9
  10 There are 4 possible config options:
  11  DNS_OPTION_IPV4: issue only one ipv4 query
  12  DNS_OPTION_IPV6: issue only one ipv6 query
  13  DNS_OPTION_PREFER_IPV4: issue the ipv4 query first and fallback to ipv6
  14  DNS_OPTION_PREFER_IPV6: issue the ipv6 query first and fallback to ipv4
  15 However, there is no code yet to set such config option. The default is
  16 DNS_OPTION_PREFER_IPV4.
  17
  18 Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=860829
  19 ---
  20  grub-core/net/dns.c | 99 ++++++++++++++++++++++++++++++++++++-----------------
  21  include/grub/net.h  |  9 +++++
  22  2 files changed, 76 insertions(+), 32 deletions(-)
  23
  24 diff --git a/grub-core/net/dns.c b/grub-core/net/dns.c
  25 index 3381ea7..725725c 100644
  26 --- a/grub-core/net/dns.c
  27 +++ b/grub-core/net/dns.c
  28 @@ -34,6 +34,14 @@ struct dns_cache_element
  29  #define DNS_CACHE_SIZE 1021
  30  #define DNS_HASH_BASE 423
  31
  32 +typedef enum grub_dns_qtype_id
  33 +  {
  34 +    GRUB_DNS_QTYPE_A = 1,
  35 +    GRUB_DNS_QTYPE_AAAA = 28
  36 +  } grub_dns_qtype_id_t;
  37 +
  38 +static grub_dns_option_t dns_type_option = DNS_OPTION_PREFER_IPV4;
  39 +
  40  static struct dns_cache_element dns_cache[DNS_CACHE_SIZE];
  41  static struct grub_net_network_level_address *dns_servers;
  42  static grub_size_t dns_nservers, dns_servers_alloc;
  43 @@ -410,13 +418,13 @@ recv_hook (grub_net_udp_socket_t sock __attribute__ ((unused)),
  44    return GRUB_ERR_NONE;
  45  }
  46
  47 -grub_err_t
  48 -grub_net_dns_lookup (const char *name,
  49 +static grub_err_t
  50 +grub_net_dns_lookup_qtype (const char *name,
  51                      const struct grub_net_network_level_address *servers,
  52                      grub_size_t n_servers,
  53                      grub_size_t *naddresses,
  54                      struct grub_net_network_level_address **addresses,
  55 -                    int cache)
  56 +                    int cache, grub_dns_qtype_id_t qtype)
  57  {
  58    grub_size_t send_servers = 0;
  59    grub_size_t i, j;
  60 @@ -471,8 +479,7 @@ grub_net_dns_lookup (const char *name,
  61                            + GRUB_NET_MAX_LINK_HEADER_SIZE
  62                            + GRUB_NET_UDP_HEADER_SIZE
  63                            + sizeof (struct dns_header)
  64 -                          + grub_strlen (name) + 2 + 4
  65 -                          + 2 + 4);
  66 +                          + grub_strlen (name) + 2 + 4);
  67    if (!nb)
  68      {
  69        grub_free (data.name);
  70 @@ -482,7 +489,7 @@ grub_net_dns_lookup (const char *name,
  71                         + GRUB_NET_MAX_LINK_HEADER_SIZE
  72                         + GRUB_NET_UDP_HEADER_SIZE);
  73    grub_netbuff_put (nb, sizeof (struct dns_header)
  74 -                   + grub_strlen (name) + 2 + 4 + 2 + 4);
  75 +                   + grub_strlen (name) + 2 + 4);
  76    head = (struct dns_header *) nb->data;
  77    optr = (grub_uint8_t *) (head + 1);
  78    for (iptr = name; *iptr; )
  79 @@ -509,18 +516,7 @@ grub_net_dns_lookup (const char *name,
  80
  81    /* Type: A.  */
  82    *optr++ = 0;
  83 -  *optr++ = 1;
  84 -
  85 -  /* Class.  */
  86 -  *optr++ = 0;
  87 -  *optr++ = 1;
  88 -
  89 -  /* Compressed name.  */
  90 -  *optr++ = 0xc0;
  91 -  *optr++ = 0x0c;
  92 -  /* Type: AAAA.  */
  93 -  *optr++ = 0;
  94 -  *optr++ = 28;
  95 +  *optr++ = qtype;
  96
  97    /* Class.  */
  98    *optr++ = 0;
  99 @@ -529,7 +525,7 @@ grub_net_dns_lookup (const char *name,
 100    head->id = data.id;
 101    head->flags = FLAGS_RD;
 102    head->ra_z_r_code = 0;
 103 -  head->qdcount = grub_cpu_to_be16_compile_time (2);
 104 +  head->qdcount = grub_cpu_to_be16_compile_time (1);
 105    head->ancount = grub_cpu_to_be16_compile_time (0);
 106    head->nscount = grub_cpu_to_be16_compile_time (0);
 107    head->arcount = grub_cpu_to_be16_compile_time (0);
 108 @@ -587,16 +583,47 @@ grub_net_dns_lookup (const char *name,
 109    if (*data.naddresses)
 110      return GRUB_ERR_NONE;
 111    if (data.dns_err)
 112 -    return grub_error (GRUB_ERR_NET_NO_DOMAIN,
 113 -                      N_("no DNS record found"));
 114 -
 115 +    {
 116 +      grub_dprintf ("dns", "%s. QTYPE: %u QNAME: %s\n",
 117 +                    N_("no DNS record found"), qtype, name);
 118 +      return GRUB_ERR_NET_NO_DOMAIN;
 119 +    }
 120    if (err)
 121      {
 122        grub_errno = err;
 123        return err;
 124      }
 125 -  return grub_error (GRUB_ERR_TIMEOUT,
 126 -                    N_("no DNS reply received"));
 127 +  grub_dprintf ("dns", "%s. QTYPE: %u QNAME: %s\n",
 128 +                N_("no DNS reply received"), qtype, name);
 129 +  return GRUB_ERR_TIMEOUT;
 130 +}
 131 +
 132 +grub_err_t
 133 +grub_net_dns_lookup (const char *name,
 134 +                    const struct grub_net_network_level_address *servers,
 135 +                    grub_size_t n_servers,
 136 +                    grub_size_t *naddresses,
 137 +                    struct grub_net_network_level_address **addresses,
 138 +                    int cache)
 139 +{
 140 +  if (dns_type_option == DNS_OPTION_IPV6 || dns_type_option == DNS_OPTION_PREFER_IPV6)
 141 +      grub_net_dns_lookup_qtype (name, servers, n_servers, naddresses,
 142 +                                 addresses, cache, GRUB_DNS_QTYPE_AAAA);
 143 +  else
 144 +      grub_net_dns_lookup_qtype (name, servers, n_servers, naddresses,
 145 +                                 addresses, cache, GRUB_DNS_QTYPE_A);
 146 +  if (!*naddresses)
 147 +    {
 148 +      if (dns_type_option == DNS_OPTION_PREFER_IPV4)
 149 +          grub_net_dns_lookup_qtype (name, servers, n_servers, naddresses,
 150 +                                     addresses, cache, GRUB_DNS_QTYPE_AAAA);
 151 +      else if (dns_type_option == DNS_OPTION_PREFER_IPV6)
 152 +          grub_net_dns_lookup_qtype (name, servers, n_servers, naddresses,
 153 +                                     addresses, cache, GRUB_DNS_QTYPE_A);
 154 +    }
 155 +  if (!*naddresses)
 156 +      return GRUB_ERR_NET_NO_DOMAIN;
 157 +  return GRUB_ERR_NONE;
 158  }
 159
 160  static grub_err_t
 161 @@ -604,22 +631,28 @@ grub_cmd_nslookup (struct grub_command *cmd __attribute__ ((unused)),
 162                    int argc, char **args)
 163  {
 164    grub_err_t err;
 165 -  grub_size_t naddresses, i;
 166 +  struct grub_net_network_level_address cmd_server;
 167 +  struct grub_net_network_level_address *servers;
 168 +  grub_size_t nservers, i, naddresses = 0;
 169    struct grub_net_network_level_address *addresses = 0;
 170    if (argc != 2 && argc != 1)
 171      return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("two arguments expected"));
 172    if (argc == 2)
 173      {
 174 -      struct grub_net_network_level_address server;
 175 -      err = grub_net_resolve_address (args[1], &server);
 176 +      err = grub_net_resolve_address (args[1], &cmd_server);
 177        if (err)
 178         return err;
 179 -      err = grub_net_dns_lookup (args[0], &server, 1, &naddresses,
 180 -                                &addresses, 0);
 181 +      servers = &cmd_server;
 182 +      nservers = 1;
 183      }
 184    else
 185 -    err = grub_net_dns_lookup (args[0], dns_servers, dns_nservers, &naddresses,
 186 -                              &addresses, 0);
 187 +    {
 188 +      servers = dns_servers;
 189 +      nservers = dns_nservers;
 190 +    }
 191 +
 192 +  grub_net_dns_lookup (args[0], servers, nservers, &naddresses,
 193 +                       &addresses, 0);
 194
 195    for (i = 0; i < naddresses; i++)
 196      {
 197 @@ -628,7 +661,9 @@ grub_cmd_nslookup (struct grub_command *cmd __attribute__ ((unused)),
 198        grub_printf ("%s\n", buf);
 199      }
 200    grub_free (addresses);
 201 -  return GRUB_ERR_NONE;
 202 +  if (naddresses)
 203 +    return GRUB_ERR_NONE;
 204 +  return grub_error (GRUB_ERR_NET_NO_DOMAIN, N_("no DNS record found"));
 205  }
 206
 207  static grub_err_t
 208 diff --git a/include/grub/net.h b/include/grub/net.h
 209 index 3877451..a7e5b2c 100644
 210 --- a/include/grub/net.h
 211 +++ b/include/grub/net.h
 212 @@ -505,6 +505,15 @@ grub_err_t
 213  grub_net_link_layer_resolve (struct grub_net_network_level_interface *inf,
 214                              const grub_net_network_level_address_t *proto_addr,
 215                              grub_net_link_level_address_t *hw_addr);
 216 +
 217 +typedef enum
 218 +  {
 219 +    DNS_OPTION_IPV4,
 220 +    DNS_OPTION_IPV6,
 221 +    DNS_OPTION_PREFER_IPV4,
 222 +    DNS_OPTION_PREFER_IPV6
 223 +  } grub_dns_option_t;
 224 +
 225  grub_err_t
 226  grub_net_dns_lookup (const char *name,
 227                      const struct grub_net_network_level_address *servers,
 228 --
 229 1.7.11.4
 230