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|
/*
*
* Resolver library with GLib integration
*
* Copyright (C) 2009-2010 Intel Corporation. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program 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 this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <errno.h>
#include <unistd.h>
#include <stdarg.h>
#include <string.h>
#include <stdlib.h>
#include <resolv.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include "gresolv.h"
struct sort_result {
int precedence;
int scope;
int src_label;
int dst_label;
gboolean reachable;
union {
struct sockaddr sa;
struct sockaddr_in sin;
struct sockaddr_in6 sin6;
} src;
union {
struct sockaddr sa;
struct sockaddr_in sin;
struct sockaddr_in6 sin6;
} dst;
};
struct resolv_query;
struct resolv_lookup {
GResolv *resolv;
guint id;
int nr_results;
struct sort_result *results;
struct resolv_query *ipv4_query;
struct resolv_query *ipv6_query;
guint ipv4_status;
guint ipv6_status;
GResolvResultFunc result_func;
gpointer result_data;
};
struct resolv_query {
GResolv *resolv;
guint timeout;
uint16_t msgid;
struct resolv_lookup *lookup;
};
struct resolv_nameserver {
GResolv *resolv;
char *address;
uint16_t port;
unsigned long flags;
GIOChannel *udp_channel;
guint udp_watch;
};
struct _GResolv {
gint ref_count;
guint next_lookup_id;
GQueue *lookup_queue;
GQueue *query_queue;
int index;
GList *nameserver_list;
struct __res_state res;
GResolvDebugFunc debug_func;
gpointer debug_data;
};
static void sort_and_return_results(struct resolv_lookup *lookup);
static void rfc3484_sort_results(struct resolv_lookup *lookup);
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 destroy_query(struct resolv_query *query)
{
if (query->timeout > 0)
g_source_remove(query->timeout);
g_free(query);
}
static void destroy_lookup(struct resolv_lookup *lookup)
{
if (lookup->ipv4_query) {
destroy_query(lookup->ipv4_query);
g_queue_remove(lookup->resolv->query_queue, lookup->ipv4_query);
}
if (lookup->ipv6_query) {
destroy_query(lookup->ipv6_query);
g_queue_remove(lookup->resolv->query_queue, lookup->ipv4_query);
}
g_free(lookup->results);
g_free(lookup);
}
static gboolean query_timeout(gpointer user_data)
{
struct resolv_query *query = user_data;
struct resolv_lookup *lookup = query->lookup;
GResolv *resolv = query->resolv;
query->timeout = 0;
if (query == lookup->ipv4_query) {
lookup->ipv4_status = G_RESOLV_RESULT_STATUS_NO_RESPONSE;
lookup->ipv4_query = NULL;
} else if (query == lookup->ipv6_query) {
lookup->ipv6_status = G_RESOLV_RESULT_STATUS_NO_RESPONSE;
lookup->ipv6_query = NULL;
}
if (!lookup->ipv4_query && !lookup->ipv4_query)
sort_and_return_results(lookup);
destroy_query(query);
g_queue_remove(resolv->query_queue, query);
return FALSE;
}
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);
g_free(nameserver->address);
g_free(nameserver);
}
static void flush_nameservers(GResolv *resolv)
{
GList *list;
for (list = g_list_first(resolv->nameserver_list);
list; list = g_list_next(list))
free_nameserver(list->data);
g_list_free(resolv->nameserver_list);
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 gint compare_lookup_id(gconstpointer a, gconstpointer b)
{
const struct resolv_lookup *lookup = a;
guint id = GPOINTER_TO_UINT(b);
if (lookup->id < id)
return -1;
if (lookup->id > id)
return 1;
return 0;
}
static gint compare_query_msgid(gconstpointer a, gconstpointer b)
{
const struct resolv_query *query = a;
uint16_t msgid = GPOINTER_TO_UINT(b);
if (query->msgid < msgid)
return -1;
if (query->msgid > msgid)
return 1;
return 0;
}
static void add_result(struct resolv_lookup *lookup, int family, const void *data)
{
int n = lookup->nr_results++;
lookup->results = g_realloc(lookup->results,
sizeof(struct sort_result) * (n+1));
memset(&lookup->results[n], 0, sizeof(struct sort_result));
lookup->results[n].dst.sa.sa_family = family;
if (family == AF_INET)
memcpy(&lookup->results[n].dst.sin.sin_addr, data, NS_INADDRSZ);
else
memcpy(&lookup->results[n].dst.sin6.sin6_addr, data, NS_IN6ADDRSZ);
}
static void parse_response(struct resolv_nameserver *nameserver,
const unsigned char *buf, int len)
{
GResolv *resolv = nameserver->resolv;
GResolvResultStatus status;
struct resolv_query *query;
struct resolv_lookup *lookup;
GList *list;
ns_msg msg;
ns_rr rr;
int i, n, rcode, count;
debug(resolv, "response from %s", nameserver->address);
ns_initparse(buf, len, &msg);
rcode = ns_msg_getflag(msg, ns_f_rcode);
count = ns_msg_count(msg, ns_s_an);
debug(resolv, "msg id: 0x%04x rcode: %d count: %d",
ns_msg_id(msg), rcode, count);
switch (rcode) {
case 0:
status = G_RESOLV_RESULT_STATUS_SUCCESS;
break;
case 1:
status = G_RESOLV_RESULT_STATUS_FORMAT_ERROR;
break;
case 2:
status = G_RESOLV_RESULT_STATUS_SERVER_FAILURE;
break;
case 3:
status = G_RESOLV_RESULT_STATUS_NAME_ERROR;
break;
case 4:
status = G_RESOLV_RESULT_STATUS_NOT_IMPLEMENTED;
break;
case 5:
status = G_RESOLV_RESULT_STATUS_REFUSED;
break;
default:
status = G_RESOLV_RESULT_STATUS_ERROR;
break;
}
list = g_queue_find_custom(resolv->query_queue,
GUINT_TO_POINTER(ns_msg_id(msg)), compare_query_msgid);
if (!list)
return;
query = list->data;
lookup = query->lookup;
if (query == lookup->ipv6_query) {
lookup->ipv6_status = status;
lookup->ipv6_query = NULL;
} else if (query == lookup->ipv4_query) {
lookup->ipv4_status = status;
lookup->ipv4_query = NULL;
}
for (i = 0, n = 0; i < count; i++) {
ns_parserr(&msg, ns_s_an, i, &rr);
if (ns_rr_class(rr) != ns_c_in)
continue;
g_assert(offsetof(struct sockaddr_in, sin_addr) ==
offsetof(struct sockaddr_in6, sin6_flowinfo));
if (ns_rr_type(rr) == ns_t_a &&
ns_rr_rdlen(rr) == NS_INADDRSZ) {
add_result(lookup, AF_INET, ns_rr_rdata(rr));
} else if (ns_rr_type(rr) == ns_t_aaaa &&
ns_rr_rdlen(rr) == NS_IN6ADDRSZ) {
add_result(lookup, AF_INET6, ns_rr_rdata(rr));
}
}
if (!lookup->ipv4_query && !lookup->ipv6_query)
sort_and_return_results(lookup);
destroy_query(query);
g_queue_remove(resolv->query_queue, query);
}
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 addrinfo hints, *rp;
char portnr[6];
int err, sk;
memset(&hints, 0, sizeof(hints));
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_DGRAM;
hints.ai_flags = AI_PASSIVE | AI_NUMERICSERV | AI_NUMERICHOST;
sprintf(portnr, "%d", nameserver->port);
err = getaddrinfo(nameserver->address, portnr, &hints, &rp);
if (err)
return -EINVAL;
/* Do not blindly copy this code elsewhere; it doesn't loop over the
results using ->ai_next as it should. That's OK in *this* case
because it was a numeric lookup; we *know* there's only one. */
if (!rp)
return -EINVAL;
sk = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
if (sk < 0) {
freeaddrinfo(rp);
return -EIO;
}
if (connect(sk, rp->ai_addr, rp->ai_addrlen) < 0) {
close(sk);
freeaddrinfo(rp);
return -EIO;
}
freeaddrinfo(rp);
nameserver->udp_channel = g_io_channel_unix_new(sk);
if (nameserver->udp_channel == NULL) {
close(sk);
return -ENOMEM;
}
g_io_channel_set_close_on_unref(nameserver->udp_channel, TRUE);
nameserver->udp_watch = g_io_add_watch(nameserver->udp_channel,
G_IO_IN | G_IO_NVAL | G_IO_ERR | G_IO_HUP,
received_udp_data, nameserver);
return 0;
}
GResolv *g_resolv_new(int index)
{
GResolv *resolv;
if (index < 0)
return NULL;
resolv = g_try_new0(GResolv, 1);
if (resolv == NULL)
return NULL;
resolv->ref_count = 1;
resolv->next_lookup_id = 1;
resolv->query_queue = g_queue_new();
if (resolv->query_queue == NULL) {
g_free(resolv);
return NULL;
}
resolv->lookup_queue = g_queue_new();
if (resolv->lookup_queue == NULL) {
g_queue_free(resolv->query_queue);
g_free(resolv);
return NULL;
}
resolv->index = index;
resolv->nameserver_list = NULL;
res_ninit(&resolv->res);
return resolv;
}
GResolv *g_resolv_ref(GResolv *resolv)
{
if (resolv == NULL)
return NULL;
g_atomic_int_inc(&resolv->ref_count);
return resolv;
}
void g_resolv_unref(GResolv *resolv)
{
struct resolv_query *query;
if (resolv == NULL)
return;
if (g_atomic_int_dec_and_test(&resolv->ref_count) == FALSE)
return;
while ((query = g_queue_pop_head(resolv->query_queue)))
destroy_query(query);
g_queue_free(resolv->query_queue);
g_queue_free(resolv->lookup_queue);
flush_nameservers(resolv);
res_nclose(&resolv->res);
g_free(resolv);
}
void g_resolv_set_debug(GResolv *resolv,
GResolvDebugFunc func, gpointer user_data)
{
if (resolv == NULL)
return;
resolv->debug_func = func;
resolv->debug_data = user_data;
}
gboolean g_resolv_add_nameserver(GResolv *resolv, const char *address,
uint16_t port, unsigned long flags)
{
struct resolv_nameserver *nameserver;
if (resolv == NULL)
return FALSE;
nameserver = g_try_new0(struct resolv_nameserver, 1);
if (nameserver == NULL)
return FALSE;
nameserver->address = g_strdup(address);
nameserver->port = port;
nameserver->flags = flags;
if (connect_udp_channel(nameserver) < 0) {
free_nameserver(nameserver);
return FALSE;
}
nameserver->resolv = resolv;
resolv->nameserver_list = g_list_append(resolv->nameserver_list,
nameserver);
debug(resolv, "setting nameserver %s", address);
return TRUE;
}
void g_resolv_flush_nameservers(GResolv *resolv)
{
if (resolv == NULL)
return;
flush_nameservers(resolv);
}
static void sort_and_return_results(struct resolv_lookup *lookup)
{
char buf[100];
GResolvResultStatus status;
char **results = g_try_new0(char *, lookup->nr_results + 1);
int i, n = 0;
if (!results)
return;
rfc3484_sort_results(lookup);
for (i = 0; i < lookup->nr_results; i++) {
if (lookup->results[i].dst.sa.sa_family == AF_INET) {
if (!inet_ntop(AF_INET, &lookup->results[i].dst.sin.sin_addr,
buf, sizeof(buf)))
continue;
} else if (lookup->results[i].dst.sa.sa_family == AF_INET6) {
if (!inet_ntop(AF_INET6, &lookup->results[i].dst.sin6.sin6_addr,
buf, sizeof(buf)))
continue;
} else
continue;
results[n++] = strdup(buf);
}
results[n++] = NULL;
status = lookup->ipv4_status;
if (status == G_RESOLV_RESULT_STATUS_SUCCESS)
status = lookup->ipv6_status;
lookup->result_func(status, results, lookup->result_data);
g_strfreev(results);
g_queue_remove(lookup->resolv->lookup_queue, lookup);
destroy_lookup(lookup);
}
static gint add_query(struct resolv_lookup *lookup, const char *hostname, int type)
{
struct resolv_query *query = g_try_new0(struct resolv_query, 1);
unsigned char buf[4096];
int len;
if (query == NULL)
return -ENOMEM;
len = res_mkquery(ns_o_query, hostname, ns_c_in, type,
NULL, 0, NULL, buf, sizeof(buf));
query->msgid = buf[0] << 8 | buf[1];
if (send_query(lookup->resolv, buf, len) < 0)
return -EIO;
query->resolv = lookup->resolv;
query->lookup = lookup;
g_queue_push_tail(lookup->resolv->query_queue, query);
query->timeout = g_timeout_add_seconds(5, query_timeout, query);
if (type == ns_t_aaaa)
lookup->ipv6_query = query;
else
lookup->ipv4_query = query;
return 0;
}
guint g_resolv_lookup_hostname(GResolv *resolv, const char *hostname,
GResolvResultFunc func, gpointer user_data)
{
struct resolv_lookup *lookup;
debug(resolv, "lookup hostname %s", hostname);
if (resolv == NULL)
return 0;
if (resolv->nameserver_list == NULL) {
int i;
for (i = 0; i < resolv->res.nscount; i++) {
char buf[100];
int family = resolv->res.nsaddr_list[i].sin_family;
void *sa_addr = &resolv->res.nsaddr_list[i].sin_addr;
if (family != AF_INET && resolv->res._u._ext.nsaddrs[i]) {
family = AF_INET6;
sa_addr = &resolv->res._u._ext.nsaddrs[i]->sin6_addr;
}
if (family != AF_INET && family != AF_INET6)
continue;
if (inet_ntop(family, sa_addr, buf, sizeof(buf)))
g_resolv_add_nameserver(resolv, buf, 53, 0);
}
if (resolv->nameserver_list == NULL)
g_resolv_add_nameserver(resolv, "127.0.0.1", 53, 0);
}
lookup = g_try_new0(struct resolv_lookup, 1);
if (!lookup)
return 0;
lookup->resolv = resolv;
lookup->result_func = func;
lookup->result_data = user_data;
lookup->id = resolv->next_lookup_id++;
if (add_query(lookup, hostname, ns_t_a)) {
g_free(lookup);
return -EIO;
}
if (add_query(lookup, hostname, ns_t_aaaa)) {
destroy_query(lookup->ipv4_query);
g_queue_remove(resolv->query_queue, lookup->ipv4_query);
g_free(lookup);
return -EIO;
}
g_queue_push_tail(resolv->lookup_queue, lookup);
return lookup->id;
}
gboolean g_resolv_cancel_lookup(GResolv *resolv, guint id)
{
GList *list;
list = g_queue_find_custom(resolv->lookup_queue,
GUINT_TO_POINTER(id), compare_lookup_id);
if (list == NULL)
return FALSE;
destroy_lookup(list->data);
g_queue_remove(resolv->query_queue, list->data);
return TRUE;
}
static void find_srcaddr(struct sort_result *res)
{
int fd;
socklen_t sl = sizeof(res->src);
fd = socket(res->dst.sa.sa_family, SOCK_DGRAM, IPPROTO_IP);
if (fd < 0)
return;
if (connect(fd, &res->dst.sa, sizeof(res->dst))) {
close(fd);
return;
}
if (getsockname(fd, &res->src.sa, &sl)) {
close(fd);
return;
}
res->reachable = TRUE;
close(fd);
}
struct gai_table
{
unsigned char addr[NS_IN6ADDRSZ];
int mask;
int value;
};
static const struct gai_table gai_labels[] = {
{
.addr = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 },
.mask = 128,
.value = 0,
}, {
.addr = { 0x20, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
.mask = 16,
.value = 2,
}, {
.addr = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
.mask = 96,
.value = 3,
}, {
.addr = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00 },
.mask = 96,
.value = 4,
}, {
/* Variations from RFC 3484, matching glibc behaviour */
.addr = { 0xfe, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
.mask = 10,
.value = 5,
}, {
.addr = { 0xfc, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
.mask = 7,
.value = 6,
}, {
.addr = { 0x20, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
.mask = 32,
.value = 7,
}, {
/* catch-all */
.addr = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
.mask = 0,
.value = 1,
}
};
static const struct gai_table gai_precedences[] = {
{
.addr = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 },
.mask = 128,
.value = 50,
}, {
.addr = { 0x20, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
.mask = 16,
.value = 30,
}, {
.addr = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
.mask = 96,
.value = 20,
}, {
.addr = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00 },
.mask = 96,
.value = 10,
}, {
.addr = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
.mask = 0,
.value = 40,
}
};
static unsigned char v4mapped[] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00 };
static gboolean mask_compare(const unsigned char *one, const unsigned char *two, int mask)
{
if (mask > 8) {
if (memcmp(one, two, mask / 8))
return FALSE;
one += mask / 8;
two += mask / 8;
mask %= 8;
}
if (mask && ((*one ^ *two) >> (8-mask)))
return FALSE;
return TRUE;
}
static int match_gai_table(struct sockaddr *sa, const struct gai_table *tbl)
{
struct sockaddr_in *sin = (void *)sa;
struct sockaddr_in6 *sin6 = (void *)sa;
void *addr;
if (sa->sa_family == AF_INET) {
addr = v4mapped;
memcpy(v4mapped+12, &sin->sin_addr, NS_INADDRSZ);
} else
addr = &sin6->sin6_addr;
while (1) {
if (mask_compare(addr, tbl->addr, tbl->mask))
return tbl->value;
tbl++;
}
}
static int rfc3484_compare(const void *__one, const void *__two)
{
const struct sort_result *one = __one;
const struct sort_result *two = __two;
/* Rule 1: Avoid unusable destinations */
if (one->reachable && !two->reachable)
return -1;
else if (two->reachable && !one->reachable)
return 1;
/* Rule 2: Prefer matching scope */
/* Rule 3: Avoid deprecated addresses */
/* Rule 4: Prefer home addresses */
/* Rule 5: Prefer matching label */
if (one->dst_label == one->src_label &&
two->dst_label != two->src_label)
return -1;
else if (two->dst_label == two->src_label &&
one->dst_label != one->src_label)
return 1;
/* Rule 6: Prefer higher precedence */
if (one->precedence > two->precedence)
return -1;
else if (two->precedence > one->precedence)
return 1;
/* Rule 7: Prefer native transport */
/* Rule 8: Prefer smaller scope */
/* Rule 9: Use longest matching prefix */
/* Rule 10: Otherwise, leave the order unchanged */
if (one < two)
return -1;
else
return 1;
}
static void rfc3484_sort_results(struct resolv_lookup *lookup)
{
int i;
for (i = 0; i < lookup->nr_results; i++) {
struct sort_result *res = &lookup->results[i];
find_srcaddr(res);
res->precedence = match_gai_table(&res->dst.sa, gai_precedences);
res->dst_label = match_gai_table(&res->dst.sa, gai_labels);
res->src_label = match_gai_table(&res->src.sa, gai_labels);
}
qsort(lookup->results, lookup->nr_results, sizeof(struct sort_result),
rfc3484_compare);
}
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