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nuttx/libc/netdb/lib_dnsforeach.c

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/****************************************************************************
* libc/netdb/lib_dnsforeach.c
*
* Copyright (C) 2016 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>
#include <assert.h>
#include <debug.h>
#include <arpa/inet.h>
#include <nuttx/net/dns.h>
#include "netdb/lib_dns.h"
#ifdef CONFIG_NETDB_DNSCLIENT
/****************************************************************************
* Private Functions
****************************************************************************/
#ifdef CONFIG_NETDB_RESOLVCONF
static FAR char *skip_spaces(FAR char *ptr)
{
while (isspace(*ptr)) ptr++;
return ptr;
}
static FAR char *find_spaces(FAR char *ptr)
{
while (*ptr && !isspace(*ptr)) ptr++;
return ptr;
}
#endif
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: dns_foreach_nameserver
*
* Description:
* Traverse each nameserver entry in the resolv.conf file and perform the
* the provided callback.
*
****************************************************************************/
#ifdef CONFIG_NETDB_RESOLVCONF
int dns_foreach_nameserver(dns_callback_t callback, FAR void *arg)
{
union dns_server_u u;
FAR FILE *stream;
char line[DNS_MAX_LINE];
FAR char *addrstr;
FAR char *ptr;
uint16_t port;
int keylen;
int ret;
/* Open the resolver configuration file */
stream = fopen(CONFIG_NETDB_RESOLVCONF_PATH, "rb");
if (stream == NULL)
{
int errcode = errno;
nerr("ERROR: Failed to open %s: %d\n",
CONFIG_NETDB_RESOLVCONF_PATH, errcode);
DEBUGASSERT(errcode > 0);
return -errcode;
}
keylen = strlen(NETDB_DNS_KEYWORD);
while (fgets(line, DNS_MAX_LINE, stream) != NULL)
{
ptr = skip_spaces(line);
if (strncmp(ptr, NETDB_DNS_KEYWORD, keylen) == 0)
{
/* Skip over the 'nameserver' keyword */
ptr = find_spaces(ptr);
addrstr = skip_spaces(ptr);
if (*addrstr == '\0')
{
nerr("ERROR: Missing address in %s record\n",
CONFIG_NETDB_RESOLVCONF_PATH);
continue;
}
/* Make sure that the address string is NUL terminated and
* not followed by garbage.
*/
ptr = find_spaces(addrstr);
*ptr = '\0';
/* Convert the address string to a binary representation. */
port = HTONS(DNS_DEFAULT_PORT);
#ifdef CONFIG_NETDB_RESOLVCONF_NONSTDPORT
/* The OpenBSD version supports a [host]:port syntax. When a
* non-standard port is specified the host address must be
* enclosed in square brackets. For example:
*
* nameserver [10.0.0.1]:5353
* nameserver [::1]:5353
*/
if (*addrstr == '[')
{
/* Make sure that ther is a right bracket */
ptr = strchr(addrstr, ']');
if (ptr == NULL)
{
nerr("ERROR: Missing right bracket after %s\n", line);
continue;
}
/* Replace the right bracket with a NULL terminator */
addrstr++;
*ptr++ = '\0';
/* Get the port number following the right bracket */
if (*ptr == ':')
{
FAR char *portstr;
int tmp;
/* Isolate the port string */
portstr = ptr;
ptr = find_spaces(addrstr);
*ptr = '\0';
/* Get the port number */
tmp = atoi(portstr);
if (tmp != 0)
{
port = htons(tmp);
}
}
}
#endif /* CONFIG_NETDB_RESOLVCONF_NONSTDPORT */
#ifdef CONFIG_NET_IPv4
/* Try to convert the IPv4 address */
ret = inet_pton(AF_INET, addrstr, &u.ipv4.sin_addr);
/* The inet_pton() function returns 1 if the conversion succeeds */
if (ret == 1)
{
u.ipv4.sin_family = AF_INET;
u.ipv4.sin_port = port;
ret = callback(arg, (FAR struct sockaddr *)&u.ipv4,
sizeof(struct sockaddr_in));
}
else
#endif
#ifdef CONFIG_NET_IPv6
{
/* Try to convert the IPv6 address */
ret = inet_pton(AF_INET6, addrstr, &u.ipv6.sin6_addr);
/* The inet_pton() function returns 1 if the conversion
* succeeds.
*/
if (ret == 1)
{
u.ipv6.sin6_family = AF_INET6;
u.ipv6.sin6_port = port;
ret = callback(arg, (FAR struct sockaddr *)&u.ipv6,
sizeof(struct sockaddr_in6));
}
else
#endif
{
nerr("ERROR: Unrecognized address: %s\n", addrstr)
ret = OK;
}
#ifdef CONFIG_NET_IPv6
}
#endif
if (ret != OK)
{
fclose(stream);
return ret;
}
}
}
fclose(stream);
return OK;
}
#else /* CONFIG_NETDB_RESOLVCONF */
int dns_foreach_nameserver(dns_callback_t callback, FAR void *arg)
{
int ret = OK;
if (g_dns_address)
{
#ifdef CONFIG_NET_IPv4
/* Check for an IPv4 address */
if (g_dns_server.addr.sa_family == AF_INET)
{
/* Perform the callback */
ret = callback(arg, (FAR struct sockaddr *)&g_dns_server.ipv4,
sizeof(struct sockaddr_in));
}
else
#endif
#ifdef CONFIG_NET_IPv6
/* Check for an IPv6 address */
if (g_dns_server.addr.sa_family == AF_INET6)
{
/* Perform the callback */
ret = callback(arg, (FAR struct sockaddr *)&g_dns_server.ipv6,
sizeof(struct sockaddr_in6));
}
else
#endif
{
ninfo("ERROR: Unsupported family: %d\n",
g_dns_server.addr.sa_family);
ret = -ENOSYS;
}
}
return ret;
}
#endif /* CONFIG_NETDB_RESOLVCONF */
#endif /* CONFIG_NETDB_DNSCLIENT */
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