diff options
Diffstat (limited to 'grub-core/net/dns.c')
-rw-r--r-- | grub-core/net/dns.c | 785 |
1 files changed, 785 insertions, 0 deletions
diff --git a/grub-core/net/dns.c b/grub-core/net/dns.c new file mode 100644 index 0000000..906ec7d --- /dev/null +++ b/grub-core/net/dns.c @@ -0,0 +1,785 @@ +/* + * GRUB -- GRand Unified Bootloader + * Copyright (C) 2010,2011 Free Software Foundation, Inc. + * + * GRUB is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * GRUB is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with GRUB. If not, see <http://www.gnu.org/licenses/>. + */ + +#include <grub/net.h> +#include <grub/net/udp.h> +#include <grub/command.h> +#include <grub/i18n.h> +#include <grub/err.h> +#include <grub/time.h> +#include <grub/safemath.h> + +struct dns_cache_element +{ + char *name; + grub_size_t naddresses; + struct grub_net_network_level_address *addresses; + grub_uint64_t limit_time; +}; + +#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 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; + +grub_err_t +grub_net_add_dns_server (const struct grub_net_network_level_address *s) +{ + if (dns_servers_alloc <= dns_nservers) + { + int na = dns_servers_alloc * 2; + struct grub_net_network_level_address *ns; + grub_size_t sz; + + if (na < 8) + na = 8; + + if (grub_mul (na, sizeof (ns[0]), &sz)) + return GRUB_ERR_OUT_OF_RANGE; + + ns = grub_realloc (dns_servers, sz); + if (!ns) + return grub_errno; + dns_servers_alloc = na; + dns_servers = ns; + } + dns_servers[dns_nservers++] = *s; + return GRUB_ERR_NONE; +} + +void +grub_net_remove_dns_server (const struct grub_net_network_level_address *s) +{ + grub_size_t i; + for (i = 0; i < dns_nservers; i++) + if (grub_net_addr_cmp (s, &dns_servers[i]) == 0) + break; + if (i < dns_nservers) + { + dns_servers[i] = dns_servers[dns_nservers - 1]; + dns_nservers--; + } +} + +struct dns_header +{ + grub_uint16_t id; + grub_uint8_t flags; + grub_uint8_t ra_z_r_code; + grub_uint16_t qdcount; + grub_uint16_t ancount; + grub_uint16_t nscount; + grub_uint16_t arcount; +} GRUB_PACKED; + +enum + { + FLAGS_RESPONSE = 0x80, + FLAGS_OPCODE = 0x78, + FLAGS_RD = 0x01 + }; + +enum + { + ERRCODE_MASK = 0x0f + }; + +enum + { + DNS_PORT = 53 + }; + +struct recv_data +{ + grub_size_t *naddresses; + struct grub_net_network_level_address **addresses; + int cache; + grub_uint16_t id; + int dns_err; + char *name; + const char *oname; + int stop; +}; + +static inline int +hash (const char *str) +{ + unsigned v = 0, xn = 1; + const char *ptr; + for (ptr = str; *ptr; ) + { + v = (v + xn * *ptr); + xn = (DNS_HASH_BASE * xn) % DNS_CACHE_SIZE; + ptr++; + if (((ptr - str) & 0x3ff) == 0) + v %= DNS_CACHE_SIZE; + } + return v % DNS_CACHE_SIZE; +} + +static int +check_name_real (const grub_uint8_t *name_at, const grub_uint8_t *head, + const grub_uint8_t *tail, const char *check_with, + int *length, char *set) +{ + const char *readable_ptr = check_with; + const grub_uint8_t *ptr; + char *optr = set; + int bytes_processed = 0; + if (length) + *length = 0; + for (ptr = name_at; ptr < tail && bytes_processed < tail - head + 2; ) + { + /* End marker. */ + if (!*ptr) + { + if (length && *length) + (*length)--; + if (optr && optr != set) + optr--; + if (optr) + *optr = 0; + return !readable_ptr || (*readable_ptr == 0); + } + if (*ptr & 0xc0) + { + bytes_processed += 2; + if (ptr + 1 >= tail) + return 0; + ptr = head + (((ptr[0] & 0x3f) << 8) | ptr[1]); + continue; + } + if (readable_ptr && grub_memcmp (ptr + 1, readable_ptr, *ptr) != 0) + return 0; + if (grub_memchr (ptr + 1, 0, *ptr) + || grub_memchr (ptr + 1, '.', *ptr)) + return 0; + if (readable_ptr) + readable_ptr += *ptr; + if (readable_ptr && *readable_ptr != '.' && *readable_ptr != 0) + return 0; + bytes_processed += *ptr + 1; + if (length) + *length += *ptr + 1; + if (optr) + { + grub_memcpy (optr, ptr + 1, *ptr); + optr += *ptr; + } + if (optr) + *optr++ = '.'; + if (readable_ptr && *readable_ptr) + readable_ptr++; + ptr += *ptr + 1; + } + return 0; +} + +static int +check_name (const grub_uint8_t *name_at, const grub_uint8_t *head, + const grub_uint8_t *tail, const char *check_with) +{ + return check_name_real (name_at, head, tail, check_with, NULL, NULL); +} + +static char * +get_name (const grub_uint8_t *name_at, const grub_uint8_t *head, + const grub_uint8_t *tail) +{ + int length; + char *ret; + + if (!check_name_real (name_at, head, tail, NULL, &length, NULL)) + return NULL; + ret = grub_malloc (length + 1); + if (!ret) + return NULL; + if (!check_name_real (name_at, head, tail, NULL, NULL, ret)) + { + grub_free (ret); + return NULL; + } + return ret; +} + +enum + { + DNS_CLASS_A = 1, + DNS_CLASS_CNAME = 5, + DNS_CLASS_AAAA = 28 + }; + +static grub_err_t +recv_hook (grub_net_udp_socket_t sock __attribute__ ((unused)), + struct grub_net_buff *nb, + void *data_) +{ + struct dns_header *head; + struct recv_data *data = data_; + int i, j; + grub_uint8_t *ptr, *reparse_ptr; + int redirect_cnt = 0; + char *redirect_save = NULL; + grub_uint32_t ttl_all = ~0U; + + /* Code apparently assumed that only one packet is received as response. + We may get multiple responses due to network condition, so check here + and quit early. */ + if (*data->addresses) + { + grub_netbuff_free (nb); + return GRUB_ERR_NONE; + } + + head = (struct dns_header *) nb->data; + ptr = (grub_uint8_t *) (head + 1); + if (ptr >= nb->tail) + { + grub_netbuff_free (nb); + return GRUB_ERR_NONE; + } + + if (head->id != data->id) + { + grub_netbuff_free (nb); + return GRUB_ERR_NONE; + } + if (!(head->flags & FLAGS_RESPONSE) || (head->flags & FLAGS_OPCODE)) + { + grub_netbuff_free (nb); + return GRUB_ERR_NONE; + } + if (head->ra_z_r_code & ERRCODE_MASK) + { + data->dns_err = 1; + grub_netbuff_free (nb); + return GRUB_ERR_NONE; + } + for (i = 0; i < grub_be_to_cpu16 (head->qdcount); i++) + { + if (ptr >= nb->tail) + { + grub_netbuff_free (nb); + return GRUB_ERR_NONE; + } + while (ptr < nb->tail && !((*ptr & 0xc0) || *ptr == 0)) + ptr += *ptr + 1; + if (ptr < nb->tail && (*ptr & 0xc0)) + ptr++; + ptr++; + ptr += 4; + } + *data->addresses = grub_calloc (grub_be_to_cpu16 (head->ancount), + sizeof ((*data->addresses)[0])); + if (!*data->addresses) + { + grub_errno = GRUB_ERR_NONE; + grub_netbuff_free (nb); + return GRUB_ERR_NONE; + } + reparse_ptr = ptr; + reparse: + for (i = 0, ptr = reparse_ptr; i < grub_be_to_cpu16 (head->ancount); i++) + { + int ignored = 0; + grub_uint8_t class; + grub_uint32_t ttl = 0; + grub_uint16_t length; + if (ptr >= nb->tail) + { + if (!*data->naddresses) + grub_free (*data->addresses); + return GRUB_ERR_NONE; + } + ignored = !check_name (ptr, nb->data, nb->tail, data->name); + while (ptr < nb->tail && !((*ptr & 0xc0) || *ptr == 0)) + ptr += *ptr + 1; + if (ptr < nb->tail && (*ptr & 0xc0)) + ptr++; + ptr++; + if (ptr + 10 >= nb->tail) + { + if (!*data->naddresses) + grub_free (*data->addresses); + grub_netbuff_free (nb); + return GRUB_ERR_NONE; + } + if (*ptr++ != 0) + ignored = 1; + class = *ptr++; + if (*ptr++ != 0) + ignored = 1; + if (*ptr++ != 1) + ignored = 1; + for (j = 0; j < 4; j++) + { + ttl <<= 8; + ttl |= *ptr++; + } + length = *ptr++ << 8; + length |= *ptr++; + if (ptr + length > nb->tail) + { + if (!*data->naddresses) + grub_free (*data->addresses); + grub_netbuff_free (nb); + return GRUB_ERR_NONE; + } + if (!ignored) + { + if (ttl_all > ttl) + ttl_all = ttl; + switch (class) + { + case DNS_CLASS_A: + if (length != 4) + break; + (*data->addresses)[*data->naddresses].type + = GRUB_NET_NETWORK_LEVEL_PROTOCOL_IPV4; + grub_memcpy (&(*data->addresses)[*data->naddresses].ipv4, + ptr, 4); + (*data->naddresses)++; + data->stop = 1; + break; + case DNS_CLASS_AAAA: + if (length != 16) + break; + (*data->addresses)[*data->naddresses].type + = GRUB_NET_NETWORK_LEVEL_PROTOCOL_IPV6; + grub_memcpy (&(*data->addresses)[*data->naddresses].ipv6, + ptr, 16); + (*data->naddresses)++; + data->stop = 1; + break; + case DNS_CLASS_CNAME: + if (!(redirect_cnt & (redirect_cnt - 1))) + { + grub_free (redirect_save); + redirect_save = data->name; + } + else + grub_free (data->name); + redirect_cnt++; + data->name = get_name (ptr, nb->data, nb->tail); + if (!data->name) + { + data->dns_err = 1; + grub_errno = 0; + return GRUB_ERR_NONE; + } + grub_dprintf ("dns", "CNAME %s\n", data->name); + if (grub_strcmp (redirect_save, data->name) == 0) + { + data->dns_err = 1; + grub_free (redirect_save); + return GRUB_ERR_NONE; + } + goto reparse; + } + } + ptr += length; + } + if (ttl_all && *data->naddresses && data->cache) + { + int h; + grub_dprintf ("dns", "caching for %d seconds\n", ttl_all); + h = hash (data->oname); + grub_free (dns_cache[h].name); + dns_cache[h].name = 0; + grub_free (dns_cache[h].addresses); + dns_cache[h].addresses = 0; + dns_cache[h].name = grub_strdup (data->oname); + dns_cache[h].naddresses = *data->naddresses; + dns_cache[h].addresses = grub_calloc (*data->naddresses, + sizeof (dns_cache[h].addresses[0])); + dns_cache[h].limit_time = grub_get_time_ms () + 1000 * ttl_all; + if (!dns_cache[h].addresses || !dns_cache[h].name) + { + grub_free (dns_cache[h].name); + dns_cache[h].name = 0; + grub_free (dns_cache[h].addresses); + dns_cache[h].addresses = 0; + } + grub_memcpy (dns_cache[h].addresses, *data->addresses, + *data->naddresses + * sizeof (dns_cache[h].addresses[0])); + } + grub_netbuff_free (nb); + grub_free (redirect_save); + return GRUB_ERR_NONE; +} + +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) +{ + grub_size_t send_servers = 0; + grub_size_t i, j; + struct grub_net_buff *nb; + grub_net_udp_socket_t *sockets; + grub_uint8_t *optr; + const char *iptr; + struct dns_header *head; + static grub_uint16_t id = 1; + grub_uint8_t *qtypeptr; + grub_err_t err = GRUB_ERR_NONE; + struct recv_data data = {naddresses, addresses, cache, + grub_cpu_to_be16 (id++), 0, 0, name, 0}; + grub_uint8_t *nbd; + grub_size_t try_server = 0; + + if (!servers) + { + servers = dns_servers; + n_servers = dns_nservers; + } + + if (!n_servers) + return grub_error (GRUB_ERR_BAD_ARGUMENT, + N_("no DNS servers configured")); + + *naddresses = 0; + if (cache) + { + int h; + h = hash (name); + if (dns_cache[h].name && grub_strcmp (dns_cache[h].name, name) == 0 + && grub_get_time_ms () < dns_cache[h].limit_time) + { + grub_dprintf ("dns", "retrieved from cache\n"); + *addresses = grub_malloc (dns_cache[h].naddresses + * sizeof ((*addresses)[0])); + if (!*addresses) + return grub_errno; + *naddresses = dns_cache[h].naddresses; + grub_memcpy (*addresses, dns_cache[h].addresses, + dns_cache[h].naddresses + * sizeof ((*addresses)[0])); + return GRUB_ERR_NONE; + } + } + + sockets = grub_calloc (n_servers, sizeof (sockets[0])); + if (!sockets) + return grub_errno; + + data.name = grub_strdup (name); + if (!data.name) + { + grub_free (sockets); + return grub_errno; + } + + nb = grub_netbuff_alloc (GRUB_NET_OUR_MAX_IP_HEADER_SIZE + + GRUB_NET_MAX_LINK_HEADER_SIZE + + GRUB_NET_UDP_HEADER_SIZE + + sizeof (struct dns_header) + + grub_strlen (name) + 2 + 4); + if (!nb) + { + grub_free (sockets); + grub_free (data.name); + return grub_errno; + } + grub_netbuff_reserve (nb, GRUB_NET_OUR_MAX_IP_HEADER_SIZE + + GRUB_NET_MAX_LINK_HEADER_SIZE + + GRUB_NET_UDP_HEADER_SIZE); + grub_netbuff_put (nb, sizeof (struct dns_header) + + grub_strlen (name) + 2 + 4); + head = (struct dns_header *) nb->data; + optr = (grub_uint8_t *) (head + 1); + for (iptr = name; *iptr; ) + { + const char *dot; + dot = grub_strchr (iptr, '.'); + if (!dot) + dot = iptr + grub_strlen (iptr); + if ((dot - iptr) >= 64) + { + grub_free (sockets); + grub_free (data.name); + return grub_error (GRUB_ERR_BAD_ARGUMENT, + N_("domain name component is too long")); + } + *optr = (dot - iptr); + optr++; + grub_memcpy (optr, iptr, dot - iptr); + optr += dot - iptr; + iptr = dot; + if (*iptr) + iptr++; + } + *optr++ = 0; + + /* Type. */ + *optr++ = 0; + qtypeptr = optr++; + + /* Class. */ + *optr++ = 0; + *optr++ = 1; + + head->id = data.id; + head->flags = FLAGS_RD; + head->ra_z_r_code = 0; + 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); + + nbd = nb->data; + + for (i = 0; i < n_servers * 4; i++) + { + /* Connect to a next server. */ + while (!(i & 1) && try_server < n_servers) + { + sockets[send_servers] = grub_net_udp_open (servers[try_server++], + DNS_PORT, + recv_hook, + &data); + if (!sockets[send_servers]) + { + err = grub_errno; + grub_errno = GRUB_ERR_NONE; + } + else + { + send_servers++; + break; + } + } + if (!send_servers) + goto out; + if (*data.naddresses) + goto out; + for (j = 0; j < send_servers; j++) + { + grub_err_t err2; + + grub_size_t t = 0; + do + { + nb->data = nbd; + if (servers[j].option == DNS_OPTION_IPV4 || + ((servers[j].option == DNS_OPTION_PREFER_IPV4) && (t++ == 0)) || + ((servers[j].option == DNS_OPTION_PREFER_IPV6) && (t++ == 1))) + *qtypeptr = GRUB_DNS_QTYPE_A; + else + *qtypeptr = GRUB_DNS_QTYPE_AAAA; + + grub_dprintf ("dns", "QTYPE: %u QNAME: %s\n", *qtypeptr, name); + + err2 = grub_net_send_udp_packet (sockets[j], nb); + if (err2) + { + grub_errno = GRUB_ERR_NONE; + err = err2; + } + if (*data.naddresses) + goto out; + } + while (t == 1); + } + grub_net_poll_cards (200, &data.stop); + } + out: + grub_free (data.name); + grub_netbuff_free (nb); + for (j = 0; j < send_servers; j++) + grub_net_udp_close (sockets[j]); + + grub_free (sockets); + + if (*data.naddresses) + return GRUB_ERR_NONE; + if (data.dns_err) + return grub_error (GRUB_ERR_NET_NO_DOMAIN, + N_("no DNS record found")); + + if (err) + { + grub_errno = err; + return err; + } + return grub_error (GRUB_ERR_TIMEOUT, + N_("no DNS reply received")); +} + +static grub_err_t +grub_cmd_nslookup (struct grub_command *cmd __attribute__ ((unused)), + int argc, char **args) +{ + grub_err_t err; + 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) + { + err = grub_net_resolve_address (args[1], &cmd_server); + if (err) + return err; + servers = &cmd_server; + nservers = 1; + } + else + { + servers = dns_servers; + nservers = dns_nservers; + } + + grub_net_dns_lookup (args[0], servers, nservers, &naddresses, + &addresses, 0); + + for (i = 0; i < naddresses; i++) + { + char buf[GRUB_NET_MAX_STR_ADDR_LEN]; + grub_net_addr_to_str (&addresses[i], buf); + grub_printf ("%s\n", buf); + } + grub_free (addresses); + if (naddresses) + return GRUB_ERR_NONE; + return grub_error (GRUB_ERR_NET_NO_DOMAIN, N_("no DNS record found")); +} + +static grub_err_t +grub_cmd_list_dns (struct grub_command *cmd __attribute__ ((unused)), + int argc __attribute__ ((unused)), + char **args __attribute__ ((unused))) +{ + grub_size_t i; + const char *strtype = ""; + + for (i = 0; i < dns_nservers; i++) + { + switch (dns_servers[i].option) + { + case DNS_OPTION_IPV4: + strtype = _("only ipv4"); + break; + + case DNS_OPTION_IPV6: + strtype = _("only ipv6"); + break; + + case DNS_OPTION_PREFER_IPV4: + strtype = _("prefer ipv4"); + break; + + case DNS_OPTION_PREFER_IPV6: + strtype = _("prefer ipv6"); + break; + } + + char buf[GRUB_NET_MAX_STR_ADDR_LEN]; + grub_net_addr_to_str (&dns_servers[i], buf); + grub_printf ("%s (%s)\n", buf, strtype); + } + return GRUB_ERR_NONE; +} + +static grub_err_t +grub_cmd_add_dns (struct grub_command *cmd __attribute__ ((unused)), + int argc, char **args) +{ + grub_err_t err; + struct grub_net_network_level_address server; + + if ((argc < 1) || (argc > 2)) + return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("one argument expected")); + else if (argc == 1) + server.option = DNS_OPTION_PREFER_IPV4; + else + { + if (grub_strcmp (args[1], "--only-ipv4") == 0) + server.option = DNS_OPTION_IPV4; + else if (grub_strcmp (args[1], "--only-ipv6") == 0) + server.option = DNS_OPTION_IPV6; + else if (grub_strcmp (args[1], "--prefer-ipv4") == 0) + server.option = DNS_OPTION_PREFER_IPV4; + else if (grub_strcmp (args[1], "--prefer-ipv6") == 0) + server.option = DNS_OPTION_PREFER_IPV6; + else + return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("invalid argument")); + } + + err = grub_net_resolve_address (args[0], &server); + if (err) + return err; + + return grub_net_add_dns_server (&server); +} + +static grub_err_t +grub_cmd_del_dns (struct grub_command *cmd __attribute__ ((unused)), + int argc, char **args) +{ + grub_err_t err; + struct grub_net_network_level_address server; + + if (argc != 1) + return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("one argument expected")); + err = grub_net_resolve_address (args[1], &server); + if (err) + return err; + + return grub_net_add_dns_server (&server); +} + +static grub_command_t cmd, cmd_add, cmd_del, cmd_list; + +void +grub_dns_init (void) +{ + cmd = grub_register_command ("net_nslookup", grub_cmd_nslookup, + N_("ADDRESS DNSSERVER"), + N_("Perform a DNS lookup")); + cmd_add = grub_register_command ("net_add_dns", grub_cmd_add_dns, + N_("DNSSERVER"), + N_("Add a DNS server")); + cmd_del = grub_register_command ("net_del_dns", grub_cmd_del_dns, + N_("DNSSERVER"), + N_("Remove a DNS server")); + cmd_list = grub_register_command ("net_ls_dns", grub_cmd_list_dns, + NULL, N_("List DNS servers")); +} + +void +grub_dns_fini (void) +{ + grub_unregister_command (cmd); + grub_unregister_command (cmd_add); + grub_unregister_command (cmd_del); + grub_unregister_command (cmd_list); +} |