nuttx/libs/libc/netdb/lib_gethostbyaddrr.c

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/****************************************************************************
* libs/libc/netdb/lib_gethostbyaddrr.c
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*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
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*
* http://www.apache.org/licenses/LICENSE-2.0
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*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
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*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <stdio.h>
#include <string.h>
#include <netdb.h>
#include <errno.h>
#include <arpa/inet.h>
#include <nuttx/net/loopback.h>
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#include "netdb/lib_netdb.h"
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#ifdef CONFIG_LIBC_NETDB
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/****************************************************************************
* Private Type Definitions
****************************************************************************/
/* This is the layout of the caller provided memory area */
struct hostent_info_s
{
int hi_addrtypes[CONFIG_NETDB_MAX_IPADDR];
int hi_lengths[CONFIG_NETDB_MAX_IPADDR];
FAR char *hi_addrlist[CONFIG_NETDB_MAX_IPADDR + 1];
char hi_data[1];
};
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/****************************************************************************
* Private Functions
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****************************************************************************/
/****************************************************************************
* Name: lib_lo_ipv4match
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*
* Description:
* Check if the address is the reserved IPv4 address for the local
* loopback device.
*
* Input Parameters:
* addr - The address of the host to find.
* len - The length of the address
* type - The type of the address
*
* Returned Value:
* True if the address is the IPv4 local loopback address.
*
****************************************************************************/
#if defined(CONFIG_NET_LOOPBACK) && defined(CONFIG_NET_IPv4)
static bool lib_lo_ipv4match(FAR const void *addr, socklen_t len, int type)
{
FAR struct in_addr *ipv4addr;
if (type == AF_INET && len >= sizeof(struct in_addr))
{
ipv4addr = (FAR struct in_addr *)addr;
return net_ipv4addr_maskcmp(ipv4addr->s_addr,
g_lo_ipv4addr,
g_lo_ipv4mask);
}
return false;
}
#endif
/****************************************************************************
* Name: lib_lo_ipv6match
*
* Description:
* Check if the address is the reserved IPv6 address for the local
* loopback device.
*
* Input Parameters:
* addr - The address of the host to find.
* len - The length of the address
* type - The type of the address
*
* Returned Value:
* True if the address is the IPv4 local loopback address.
*
****************************************************************************/
#if defined(CONFIG_NET_LOOPBACK) && defined(CONFIG_NET_IPv6)
static bool lib_lo_ipv6match(FAR const void *addr, socklen_t len, int type)
{
FAR struct in6_addr *ipv6addr;
if (type == AF_INET6 && len >= sizeof(struct in6_addr))
{
ipv6addr = (FAR struct in6_addr *)addr;
return net_ipv6addr_maskcmp(ipv6addr->s6_addr16,
g_lo_ipv6addr,
g_lo_ipv6mask);
}
return false;
}
#endif
/****************************************************************************
* Name: lib_localhost
*
* Description:
* Check if the address is the reserved address for the local loopback
* device.
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*
* Input Parameters:
* addr - The address of the host to find.
* len - The length of the address
* type - The type of the address
* host - Caller provided location to return the host data.
* buf - Caller provided buffer to hold string data associated with the
* host data.
* buflen - The size of the caller-provided buffer
*
* Returned Value:
* Zero (OK) is returned on success, -1 (ERROR) is returned on a failure.
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*
****************************************************************************/
#ifdef CONFIG_NET_LOOPBACK
static int lib_localhost(FAR const void *addr, socklen_t len, int type,
FAR struct hostent_s *host, FAR char *buf,
size_t buflen)
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{
FAR struct hostent_info_s *info;
FAR char *dest;
int namelen;
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/* Make sure that space remains to hold the hostent structure */
if (buflen <= sizeof(struct hostent_info_s))
{
return -ERANGE;
}
info = (FAR struct hostent_info_s *)buf;
dest = info->hi_data;
buflen -= (sizeof(struct hostent_info_s) - 1);
memset(host, 0, sizeof(struct hostent_s));
memset(info, 0, sizeof(struct hostent_info_s));
host->h_addrtypes = info->hi_addrtypes;
host->h_lengths = info->hi_lengths;
host->h_addr_list = info->hi_addrlist;
#ifdef CONFIG_NET_IPv4
if (lib_lo_ipv4match(addr, len, type))
{
/* Save the IPv4 address */
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host->h_lengths[0] = sizeof(struct in_addr);
host->h_addr_list[0] = (FAR char *)&g_lo_ipv4addr;
host->h_addrtypes[0] = AF_INET;
goto out_copyname;
}
#endif
#ifdef CONFIG_NET_IPv6
if (lib_lo_ipv6match(addr, len, type))
{
/* Save the IPv6 address */
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host->h_lengths[0] = sizeof(struct in6_addr);
host->h_addr_list[0] = (FAR char *)&g_lo_ipv6addr;
host->h_addrtypes[0] = AF_INET6;
goto out_copyname;
}
#endif
/* Return 1 meaning that we have no errors but no match either */
return 1;
out_copyname:
/* And copy localhost host name */
namelen = strlen(g_lo_hostname);
if (namelen + 1 > buflen)
{
return -ERANGE;
}
strncpy(dest, g_lo_hostname, buflen);
host->h_name = dest;
return 0;
}
#endif
/****************************************************************************
* Name: lib_hostfile_lookup
*
* Description:
* Try to look-up the host name from the network host file
*
* Input Parameters:
* addr - The address of the host to find.
* len - The length of the address
* type - The type of the address
* host - Caller provided location to return the host data.
* buf - Caller provided buffer to hold string data associated with the
* host data.
* buflen - The size of the caller-provided buffer
* h_errnop - There h_errno value returned in the event of a failure.
*
* Returned Value:
* Zero (OK) is returned on success, -1 (ERROR) is returned on a failure
* with the returned h_errno value provided the reason for the failure.
*
****************************************************************************/
#ifdef CONFIG_NETDB_HOSTFILE
int lib_hostfile_lookup(FAR const void *addr, socklen_t len, int type,
FAR struct hostent_s *host, FAR char *buf,
size_t buflen, FAR int *h_errnop)
{
FAR FILE *stream;
int herrnocode;
int nread;
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/* Search the hosts file for a match */
stream = fopen(CONFIG_NETDB_HOSTCONF_PATH, "r");
if (stream == NULL)
{
int errcode = -get_errno();
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nerr("ERROR: Failed to open the hosts file %s: %d\n",
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CONFIG_NETDB_HOSTCONF_PATH, errcode);
UNUSED(errcode);
herrnocode = NO_RECOVERY;
goto errorout_with_herrnocode;
}
/* Loop reading entries from the hosts file until a match is found or
* until we hit the end-of-file.
*/
do
{
/* Read the next entry from the hosts file */
nread = parse_hostfile(stream, host, buf, buflen);
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if (nread < 0)
{
/* Possible errors:
* ERANGE - Buffer not big enough
* ESPIPE - End of file (or possibly a read error).
* EAGAIN - Error parsing the line (E.g., missing hostname)
*/
if (nread == -ESPIPE)
{
nread = 0;
}
else if (nread != -EAGAIN)
{
herrnocode = NO_RECOVERY;
goto errorout_with_stream;
}
}
else if (len == host->h_lengths[0] && type == host->h_addrtypes[0])
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{
/* We successfully read the entry and the type and size of the
* address is good. Now compare the addresses:
*/
FAR char *hostaddr = host->h_addr_list[0];
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if (hostaddr != NULL)
{
ninfo("Comparing addresses...\n");
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if (memcmp(addr, hostaddr, len) == 0)
{
/* We have a match */
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fclose(stream);
return OK;
}
}
}
}
while (nread != 0);
/* We get here when the end of the hosts file is encountered without
* finding the hostname.
*/
herrnocode = HOST_NOT_FOUND;
errorout_with_stream:
fclose(stream);
errorout_with_herrnocode:
if (h_errnop)
{
*h_errnop = herrnocode;
}
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return ERROR;
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}
#endif
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/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: gethostbyaddr_r
*
* Description:
* The gethostbyaddr_r() function returns a structure of type hostent for
* the given host address addr of length len and address type type. Valid
* address types are AF_INET and AF_INET6. The host address argument is a
* pointer to a struct of a type depending on the address type, for example
* a struct in_addr * for address type AF_INET.
*
* gethostbyaddr_r() is *not* POSIX but is similar to a Glibc extension and
* is used internally by NuttX to implement the POSIX gethostbyaddr().
*
* Input Parameters:
* addr - The address of the host to find.
* len - The length of the address
* type - The type of the address
* host - Caller provided location to return the host data.
* buf - Caller provided buffer to hold string data associated with the
* host data.
* buflen - The size of the caller-provided buffer
* result - There host entry returned in the event of a success.
* h_errnop - There h_errno value returned in the event of a failure.
*
* Returned Value:
* Zero (OK) is returned on success, -1 (ERROR) is returned on a failure
* with the returned h_errno value provided the reason for the failure.
*
****************************************************************************/
int gethostbyaddr_r(FAR const void *addr, socklen_t len, int type,
FAR struct hostent *host, FAR char *buf,
size_t buflen, FAR struct hostent **result,
FAR int *h_errnop)
{
#if defined(CONFIG_NET_LOOPBACK) || defined(CONFIG_NETDB_HOSTFILE)
struct hostent_s tmp;
#endif
int ret;
DEBUGASSERT(addr != NULL && host != NULL && buf != NULL);
DEBUGASSERT(type == AF_INET || type == AF_INET6);
/* Linux man page says result must be NULL in case of failure. */
*result = NULL;
/* Make sure that the h_errno has a non-error code */
if (h_errnop)
{
*h_errnop = 0;
}
#ifdef CONFIG_NET_LOOPBACK
/* Check for the local loopback address */
ret = lib_localhost(addr, len, type, &tmp, buf, buflen);
if (ret == OK)
{
/* Yes.. we are done */
convert_hostent(&tmp, AF_UNSPEC, host);
*result = host;
return OK;
}
#endif
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/* TODO:
*
* 1. Look in the DNS cache to see if we have the address mapping already
* in place. If not,
* 2. Perform a reverse DNS lookup. And if that fails as well, then
* finally
* 3. Search the hosts file for a match.
*/
#ifdef CONFIG_NETDB_HOSTFILE
/* Search the hosts file for a match */
ret = lib_hostfile_lookup(addr, len, type, &tmp, buf, buflen, h_errnop);
if (ret == OK)
{
convert_hostent(&tmp, AF_UNSPEC, host);
*result = host;
return OK;
}
#else
/* The host file file is not supported. The host address mapping was not
* found from any lookup heuristic
*/
if (h_errnop)
{
*h_errnop = HOST_NOT_FOUND;
}
ret = ERROR;
#endif
return ret;
}
#endif /* CONFIG_LIBC_NETDB */