nuttx/libs/libc/netdb/lib_gethostentbynamer.c

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/****************************************************************************
* libs/libc/netdb/lib_gethostentbynamer.c
*
* 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
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* 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.
*
****************************************************************************/
/****************************************************************************
* 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 "netdb/lib_dns.h"
#include "netdb/lib_netdb.h"
#ifdef CONFIG_LIBC_NETDB
/****************************************************************************
* Private Type Definitions
****************************************************************************/
/* This is the layout of the caller provided memory area */
struct hostent_info_s
{
int hi_addrtypes[CONFIG_NETDB_MAX_IPADDR + 1];
int hi_lengths[CONFIG_NETDB_MAX_IPADDR + 1];
FAR char *hi_addrlist[CONFIG_NETDB_MAX_IPADDR + 1];
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:
* 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 name is an numeric IP address.
*
****************************************************************************/
static int lib_numeric_address(FAR const char *name,
FAR struct hostent_s *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_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;
/* 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_addrtypes[0] = 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_addrtypes[0] = AF_INET;
}
/* No colon? No period? Can't be a numeric address */
else
{
return 1;
}
host->h_addr_list[0] = ptr;
host->h_lengths[0] = addrlen;
ptr += addrlen;
buflen -= addrlen;
/* And copy name */
namelen = strlen(name);
if ((namelen + 1) > buflen)
{
return -ERANGE;
}
strncpy(ptr, name, buflen);
/* Set the address to h_name */
host->h_name = ptr;
return 0;
}
/****************************************************************************
* Name: lib_localhost
*
* Description:
* Check if the name is the reserved name for the local loopback device.
*
* 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 name is the loopback device.
*
****************************************************************************/
#ifdef CONFIG_NET_LOOPBACK
static int lib_localhost(FAR const char *name, FAR struct hostent_s *host,
FAR char *buf, size_t buflen)
{
FAR struct hostent_info_s *info;
FAR char *dest;
int namelen;
int i = 0;
if (strcmp(name, g_lo_hostname) == 0)
{
/* Yes.. it is the localhost */
/* 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
/* Save the IPv4 address */
info->hi_addrtypes[i] = AF_INET;
info->hi_lengths[i] = sizeof(struct in_addr);
info->hi_addrlist[i] = (FAR char *)&g_lo_ipv4addr;
i++;
#endif
#ifdef CONFIG_NET_IPv6
/* Save the IPv6 address */
info->hi_addrtypes[i] = AF_INET6;
info->hi_lengths[i] = sizeof(struct in6_addr);
info->hi_addrlist[i] = (FAR char *)&g_lo_ipv6addr;
i++;
#endif
/* And copy name */
namelen = strlen(name);
if ((namelen + 1) > buflen)
{
return -ERANGE;
}
strncpy(dest, name, buflen);
/* Set the address to h_name */
host->h_name = dest;
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
#if CONFIG_NETDB_DNSCLIENT_ENTRIES > 0
static int lib_find_answer(FAR const char *name, FAR struct hostent_s *host,
FAR char *buf, size_t buflen)
{
FAR struct hostent_info_s *info;
FAR char *ptr;
FAR void *addrdata;
socklen_t addrlen;
int naddr;
int addrtype;
int namelen;
int ret;
int i;
/* 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);
/* Verify again that there is space for at least one address. */
if (buflen < sizeof(union dns_addr_u))
{
return -ERANGE;
}
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;
/* Try to get the host address using the DNS name server */
naddr = buflen / sizeof(union dns_addr_u);
ret = dns_find_answer(name, (FAR union dns_addr_u *)ptr, &naddr);
if (ret < 0)
{
/* No, nothing found in the cache */
return ret;
}
DEBUGASSERT(naddr <= CONFIG_NETDB_MAX_IPADDR);
/* Get the address type. */
for (i = 0; i < naddr; i++)
{
#ifdef CONFIG_NET_IPv4
#ifdef CONFIG_NET_IPv6
if (((FAR struct sockaddr_in *)ptr)->sin_family == AF_INET)
#endif
{
addrlen = sizeof(struct in_addr);
addrtype = AF_INET;
addrdata = &((FAR struct sockaddr_in *)ptr)->sin_addr;
}
#endif
#ifdef CONFIG_NET_IPv6
#ifdef CONFIG_NET_IPv4
else
#endif
{
addrlen = sizeof(struct in6_addr);
addrtype = AF_INET6;
addrdata = &((FAR struct sockaddr_in6 *)ptr)->sin6_addr;
}
#endif
info->hi_addrtypes[i] = addrtype;
info->hi_lengths[i] = addrlen;
info->hi_addrlist[i] = addrdata;
ptr += sizeof(union dns_addr_u);
buflen -= sizeof(union dns_addr_u);
}
/* And copy name */
namelen = strlen(name);
if ((namelen + 1) > buflen)
{
return -ERANGE;
}
strncpy(ptr, name, buflen);
/* Set the address to h_name */
host->h_name = ptr;
return OK;
}
#endif
#endif /* CONFIG_NETDB_DNSCLIENT */
/****************************************************************************
* Name: lib_dns_query
*
* Description:
* 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 union dns_addr_u *addr, int *naddr)
{
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, naddr);
/* 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_s *host,
FAR char *buf, size_t buflen)
{
FAR struct hostent_info_s *info;
FAR char *ptr;
FAR void *addrdata;
socklen_t addrlen;
int naddr;
int addrtype;
int namelen;
int ret;
int i;
/* Verify that we have a buffer big enough to get started (it still may not
* be big enough).
* Verify that there is space for at least one address.
*/
namelen = strlen(name);
if (buflen < sizeof(struct hostent_info_s) - 1 + sizeof(union dns_addr_u) +
namelen + 1)
{
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_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;
/* Try to get the host address using the DNS name server */
naddr = (buflen - (namelen + 1)) / sizeof(union dns_addr_u);
DEBUGASSERT(naddr >= 1);
ret = lib_dns_query(name, (FAR union dns_addr_u *)ptr, &naddr);
if (ret < 0)
{
return ret;
}
/* We can read more than maximum, limit here. */
naddr = MIN(naddr, CONFIG_NETDB_MAX_IPADDR);
for (i = 0; i < naddr; i++)
{
#ifdef CONFIG_NET_IPv4
#ifdef CONFIG_NET_IPv6
if (((FAR struct sockaddr_in *)ptr)->sin_family == AF_INET)
#endif
{
addrlen = sizeof(struct in_addr);
addrtype = AF_INET;
addrdata = &((FAR struct sockaddr_in *)ptr)->sin_addr;
}
#endif
#ifdef CONFIG_NET_IPv6
#ifdef CONFIG_NET_IPv4
else
#endif
{
addrlen = sizeof(struct in6_addr);
addrtype = AF_INET6;
addrdata = &((FAR struct sockaddr_in6 *)ptr)->sin6_addr;
}
#endif
info->hi_addrtypes[i] = addrtype;
info->hi_lengths[i] = addrlen;
info->hi_addrlist[i] = addrdata;
DEBUGASSERT(buflen >= namelen + 1 + sizeof(union dns_addr_u));
ptr += sizeof(union dns_addr_u);
buflen -= sizeof(union dns_addr_u);
}
/* And copy name */
DEBUGASSERT(buflen >= namelen + 1);
strncpy(ptr, name, buflen);
/* Set the address to h_name */
host->h_name = ptr;
return OK;
}
#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 host file lookup was successful.
*
****************************************************************************/
#ifdef CONFIG_NETDB_HOSTFILE
static int lib_hostfile_lookup(FAR const char *name,
FAR struct hostent_s *host, FAR char *buf,
size_t buflen, FAR 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;
nerr("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 = 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 */
ninfo("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: gethostentbyname_r
*
* Description:
* The gethostentbyname_r() function returns a structure of type hostent_s
* 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
* gethostentbyname_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.
*
* 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 gethostentbyname_r(FAR const char *name,
FAR struct hostent_s *host, FAR char *buf,
size_t buflen, FAR int *h_errnop)
{
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 */
#ifdef CONFIG_NETDB_DNSCLIENT
#if CONFIG_NETDB_DNSCLIENT_ENTRIES > 0
/* Check if we already have this hostname mapping cached */
if (lib_find_answer(name, host, buf, buflen) >= 0)
{
/* Found the address mapping in the cache */
return OK;
}
#endif
/* Try to get the host address using the DNS name server */
if (lib_dns_lookup(name, host, buf, buflen) >= 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 */