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nuttx/libc/netdb/lib_gethostbynamer.c

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/****************************************************************************
* libc/netdb/lib_gethostbynamer.c
*
* Copyright (C) 2015 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 <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <string.h>
#include <netdb.h>
#include <errno.h>
#include <assert.h>
#include <arpa/inet.h>
#include <nuttx/net/dns.h>
#include <nuttx/net/loopback.h>
#include "libc.h"
#include "netdb/lib_dns.h"
#ifdef CONFIG_LIBC_NETDB
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Private Type Definitions
****************************************************************************/
/* This is the layout of the caller provided memory area */
struct hostent_info_s
{
FAR char *hi_addrlist[2];
char hi_data[1];
};
/****************************************************************************
* Private functions
****************************************************************************/
/****************************************************************************
* Name: lib_numeric_address
*
* Description:
* Check if the name is a numeric IP address. In this case, simply copy
* name into the h_name field and its struct in_addr equivalent into the
* h_addr_list[0] field of the returned hostent structure.
*
* Input Parameters:
* stream - File stream of the opened hosts file with the file pointer
* positioned at the beginning of the next host entry.
* 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 (0) is returned if the name is an numeric IP address.
*
****************************************************************************/
static int lib_numeric_address(FAR const char *name, FAR struct hostent *host,
FAR char *buf, size_t buflen)
{
FAR struct hostent_info_s *info;
FAR char *ptr;
socklen_t addrlen;
int namelen;
int ret;
/* Verify that we have a buffer big enough to get started (it still may not
* be big enough).
*/
if (buflen <= sizeof(struct hostent_info_s))
{
return -ERANGE;
}
info = (FAR struct hostent_info_s *)buf;
ptr = info->hi_data;
buflen -= (sizeof(struct hostent_info_s) - 1);
memset(host, 0, sizeof(struct hostent));
memset(info, 0, sizeof(struct hostent_info_s));
/* If the address contains a colon, then it might be a numeric IPv6
* address
*/
if (strchr(name, ':') != NULL)
{
/* Make sure that space remains to hold the IPv6 address */
addrlen = sizeof(struct in6_addr);
if (buflen < addrlen)
{
return -ERANGE;
}
ret = inet_pton(AF_INET6, name, ptr);
/* The inet_pton() function returns 1 if the conversion succeeds. It
* will return 0 if the input is not a valid IP address string, or -1
* if the address family argument is unsupported.
*/
if (ret < 1)
{
/* Conversion failed. Must not be a IPv6 address */
return 1;
}
host->h_addrtype = AF_INET6;
}
/* If the address contains a colon, then it might be a numeric IPv6
* address.
*/
else if (strchr(name, '.') != NULL)
{
/* Make sure that space remains to hold the IPv4 address */
addrlen = sizeof(struct in_addr);
if (buflen < addrlen)
{
return -ERANGE;
}
ret = inet_pton(AF_INET, name, ptr);
/* The inet_pton() function returns 1 if the conversion succeeds. It
* will return 0 if the input is not a valid IP address string, or -1
* if the address family argument is unsupported.
*/
if (ret < 1)
{
/* Conversion failed. Must not be an IPv4 address */
return 1;
}
host->h_addrtype = AF_INET;
}
/* No colon? No period? Can't be a numeric address */
else
{
return 1;
}
info->hi_addrlist[0] = ptr;
host->h_addr_list = info->hi_addrlist;
host->h_length = addrlen;
ptr += addrlen;
buflen -= addrlen;
/* And copy name */
namelen = strlen(name);
if (addrlen + namelen + 1 > buflen)
{
return -ERANGE;
}
strncpy(ptr, name, buflen);
return 0;
}
/****************************************************************************
* Name: lib_localhost
*
* Description:
* Check if the name is the reserved name for the local loopback device.
*
* Input Parameters:
* stream - File stream of the opened hosts file with the file pointer
* positioned at the beginning of the next host entry.
* 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 (0) is returned if the name is an numeric IP address.
*
****************************************************************************/
#ifdef CONFIG_NET_LOOPBACK
static int lib_localhost(FAR const char *name, FAR struct hostent *host,
FAR char *buf, size_t buflen)
{
FAR struct hostent_info_s *info;
socklen_t addrlen;
FAR const char *src;
FAR char *dest;
int namelen;
if (strcmp(name, "localhost") == 0)
{
/* Yes.. it is the localhost */
#ifdef CONFIG_NET_IPv4
/* Setup to transfer the IPv4 address */
addrlen = sizeof(struct in_addr);
src = (FAR const char *)&g_lo_ipv4addr;
host->h_addrtype = AF_INET;
#else /* CONFIG_NET_IPv6 */
/* Setup to transfer the IPv6 address */
addrlen = sizeof(struct in6_addr);
src = (FAR const char *)&g_lo_ipv6addr;
host->h_addrtype = AF_INET6;
#endif
/* Make sure that space remains to hold the hostent structure and
* the IP address.
*/
if (buflen <= (sizeof(struct hostent_info_s) + addrlen))
{
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));
memset(info, 0, sizeof(struct hostent_info_s));
memcpy(dest, src, addrlen);
info->hi_addrlist[0] = dest;
host->h_addr_list = info->hi_addrlist;
host->h_length = addrlen;
dest += addrlen;
buflen -= addrlen;
/* And copy name */
namelen = strlen(name);
if (addrlen + namelen + 1 > buflen)
{
return -ERANGE;
}
strncpy(dest, name, buflen);
return 0;
}
return 1;
}
#endif
/****************************************************************************
* Name: lib_find_answer
*
* Description:
* Check if we previously resolved this hostname and if that resolved
* address is already available in the DNS cache.
*
* Input Parameters:
* name - The name of the host to find.
* 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 (0) is returned if the DNS lookup was successful.
*
****************************************************************************/
#ifdef CONFIG_NETDB_DNSCLIENT
static int lib_find_answer(FAR const char *name, FAR struct hostent *host,
FAR char *buf, size_t buflen)
{
FAR struct hostent_info_s *info;
FAR char *ptr;
FAR void *addrdata;
socklen_t addrlen;
int addrtype;
int namelen;
int ret;
/* Verify that we have a buffer big enough to get started (it still may not
* be big enough).
*/
if (buflen <= sizeof(struct hostent_info_s))
{
return -ERANGE;
}
/* Initialize buffers */
info = (FAR struct hostent_info_s *)buf;
ptr = info->hi_data;
buflen -= (sizeof(struct hostent_info_s) - 1);
memset(host, 0, sizeof(struct hostent));
memset(info, 0, sizeof(struct hostent_info_s));
/* Try to get the host address using the DNS name server */
addrlen = buflen;
ret = dns_find_answer(name, (FAR struct sockaddr *)ptr, &addrlen);
if (ret < 0)
{
/* No, nothing found in the cache */
return ret;
}
/* Get the address type; verify the address size. */
#ifdef CONFIG_NET_IPv4
#ifdef CONFIG_NET_IPv6
if (((FAR struct sockaddr_in *)ptr)->sin_family == AF_INET)
#endif
{
DEBUGASSERT(addrlen == sizeof(struct sockaddr_in));
addrlen = sizeof(struct sockaddr_in);
addrtype = AF_INET;
addrdata = &((FAR struct sockaddr_in *)ptr)->sin_addr;
}
#endif
#ifdef CONFIG_NET_IPv6
#ifdef CONFIG_NET_IPv4
else
#endif
{
DEBUGASSERT(addrlen == sizeof(struct sockaddr_in6));
addrlen = sizeof(struct sockaddr_in6);
addrtype = AF_INET6;
addrdata = &((FAR struct sockaddr_in6 *)ptr)->sin6_addr;
}
#endif
/* Yes.. Return the address that we obtained from the DNS cache. */
info->hi_addrlist[0] = addrdata;
host->h_addr_list = info->hi_addrlist;
host->h_addrtype = addrtype;
host->h_length = addrlen;
ptr += addrlen;
buflen -= addrlen;
/* And copy the host name */
namelen = strlen(name);
if (addrlen + namelen + 1 > buflen)
{
return -ERANGE;
}
strncpy(ptr, name, buflen);
return OK;
}
#endif /* CONFIG_NETDB_DNSCLIENT */
/****************************************************************************
* Name: lib_dns_query
*
* Descriptions:
* Combines the operations of dns_bind(), dns_query(), and dns_free() to
* obtain the IP address ('ipaddr') associated with the 'hostname' in one
* operation.
*
****************************************************************************/
#ifdef CONFIG_NETDB_DNSCLIENT
static int lib_dns_query(FAR const char *hostname,
FAR struct sockaddr *addr, socklen_t *addrlen)
{
int sd;
int ret;
/* Create and bind a socket to the DNS server */
sd = dns_bind();
if (sd < 0)
{
return sd;
}
/* Perform the query to get the IP address */
ret = dns_query(sd, hostname, addr, addrlen);
/* Release the socket */
close(sd);
return ret;
}
#endif /* CONFIG_NETDB_DNSCLIENT */
/****************************************************************************
* Name: lib_dns_lookup
*
* Description:
* Try to look-up the host name from the DNS server
*
* Input Parameters:
* name - The name of the host to find.
* 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 (0) is returned if the DNS lookup was successful.
*
****************************************************************************/
#ifdef CONFIG_NETDB_DNSCLIENT
static int lib_dns_lookup(FAR const char *name, FAR struct hostent *host,
FAR char *buf, size_t buflen)
{
FAR struct hostent_info_s *info;
FAR char *ptr;
FAR void *addrdata;
socklen_t addrlen;
int addrtype;
int namelen;
int ret;
/* Verify that we have a buffer big enough to get started (it still may not
* be big enough).
*/
if (buflen <= sizeof(struct hostent_info_s))
{
return -ERANGE;
}
/* Initialize buffers */
info = (FAR struct hostent_info_s *)buf;
ptr = info->hi_data;
buflen -= (sizeof(struct hostent_info_s) - 1);
memset(host, 0, sizeof(struct hostent));
memset(info, 0, sizeof(struct hostent_info_s));
/* Try to get the host address using the DNS name server */
addrlen = buflen;
ret = lib_dns_query(name, (FAR struct sockaddr *)ptr, &addrlen);
/* Was the DNS lookup successful? */
if (ret >= 0)
{
/* Get the address type; verify the address size. */
#ifdef CONFIG_NET_IPv4
#ifdef CONFIG_NET_IPv6
if (((FAR struct sockaddr_in *)ptr)->sin_family == AF_INET)
#endif
{
DEBUGASSERT(addrlen == sizeof(struct sockaddr_in));
addrlen = sizeof(struct sockaddr_in);
addrtype = AF_INET;
addrdata = &((FAR struct sockaddr_in *)ptr)->sin_addr;
}
#endif
#ifdef CONFIG_NET_IPv6
#ifdef CONFIG_NET_IPv4
else
#endif
{
DEBUGASSERT(addrlen == sizeof(struct sockaddr_in6));
addrlen = sizeof(struct sockaddr_in6);
addrtype = AF_INET6;
addrdata = &((FAR struct sockaddr_in6 *)ptr)->sin6_addr;
}
#endif
/* Yes.. Return the address that we obtained from the DNS name server. */
info->hi_addrlist[0] = addrdata;
host->h_addr_list = info->hi_addrlist;
host->h_addrtype = addrtype;
host->h_length = addrlen;
ptr += addrlen;
buflen -= addrlen;
/* And copy name */
namelen = strlen(name);
if (addrlen + namelen + 1 > buflen)
{
return -ERANGE;
}
strncpy(ptr, name, buflen);
return OK;
}
return ret;
}
#endif /* CONFIG_NETDB_DNSCLIENT */
/****************************************************************************
* Name: lib_hostfile_lookup
*
* Description:
* Try to look-up the host name from the network host file
*
* Input Parameters:
* name - The name of the host to find.
* 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 (0) is returned if the DNS lookup was successful.
*
****************************************************************************/
#ifdef CONFIG_NETDB_HOSTFILE
static int lib_hostfile_lookup(FAR const char *name, FAR struct hostent *host,
FAR char *buf, size_t buflen, int *h_errnop)
{
FAR FILE *stream;
int herrnocode;
int nread;
/* Search the hosts file for a match */
stream = fopen(CONFIG_NETDB_HOSTCONF_PATH, "r");
if (stream == NULL)
{
int errcode = errno;
ndbg("ERROR: Failed to open the hosts file %s: %d\n",
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 = lib_parse_hostfile(stream, host, buf, buflen);
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 (nread > 0)
{
/* We successfully read the entry */
nvdbg("Comparing %s to %s\n", name, host->h_name);
/* Check for a host name match */
if (strcmp(name, host->h_name) == 0)
{
/* We have a match */
fclose(stream);
return OK;
}
/* For a match with any host alias */
if (host->h_aliases != NULL)
{
FAR char **alias;
for (alias = host->h_aliases; *alias != NULL; alias++)
{
/* Check for a host alias match */
if (strcmp(name, *alias) == 0)
{
/* We have a match */
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;
}
return ERROR;
}
#endif /* CONFIG_NETDB_HOSTFILE */
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: gethostname_r
*
* Description:
* The gethostbyname_r() function returns a structure of type hostent for
* the given host name. Here name is either a hostname, or an IPv4 address
* in standard dot notation (as for inet_addr(3)), or an IPv6 address in
* colon (and possibly dot) notation.
*
* If name is an IPv4 or IPv6 address, no lookup is performed and
* gethostbyname_r() simply copies name into the h_name field
* and its struct in_addr equivalent into the h_addr_list[0] field of the
* returned hostent structure.
*
* gethostname_r() is *not* POSIX but is similar to a Glibc extension and is
* used internally by NuttX to implement the POSIX gethostname().
*
* Input Parameters:
* name - The name of the host to find.
* 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.
*
****************************************************************************/
int gethostbyname_r(FAR const char *name, FAR struct hostent *host,
FAR char *buf, size_t buflen, int *h_errnop)
{
#ifdef CONFIG_NETDB_DNSCLIENT
int ret;
#endif
DEBUGASSERT(name != NULL && host != NULL && buf != NULL);
/* Make sure that the h_errno has a non-error code */
if (h_errnop)
{
*h_errnop = 0;
}
/* Check for a numeric hostname */
if (lib_numeric_address(name, host, buf, buflen) == 0)
{
/* Yes.. we are done */
return OK;
}
#ifdef CONFIG_NET_LOOPBACK
/* Check for the local loopback host name */
if (lib_localhost(name, host, buf, buflen) == 0)
{
/* Yes.. we are done */
return OK;
}
#endif
/* Try to find the name in the HOSTALIASES environment variable */
/* REVISIT: Not implemented */
#ifdef CONFIG_NETDB_DNSCLIENT
#if CONFIG_NETDB_DNSCLIENT_ENTRIES > 0
/* Check if we already have this hostname mapping cached */
ret = lib_find_answer(name, host, buf, buflen);
if (ret >= 0)
{
/* Found the address mapping in the cache */
return OK;
}
#endif
/* Try to get the host address using the DNS name server */
ret = lib_dns_lookup(name, host, buf, buflen);
if (ret >= 0)
{
/* Successful DNS lookup! */
return OK;
}
#endif /* CONFIG_NETDB_DNSCLIENT */
#ifdef CONFIG_NETDB_HOSTFILE
/* Search the hosts file for a match */
return lib_hostfile_lookup(name, host, buf, buflen, h_errnop);
#else
/* The host file file is not supported. The host name mapping was not
* found from any lookup heuristic
*/
if (h_errnop)
{
*h_errnop = HOST_NOT_FOUND;
}
return ERROR;
#endif
}
#endif /* CONFIG_LIBC_NETDB */
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