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netdb: Regard hosts file prior to DNS when resolving

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- Linux: What inside /etc/hosts comes first.
- NuttX: Even if we write a domain in /etc/hosts, we still use DNS
         result instead of hosts lines. This patch change this behavior.

Signed-off-by: Zhe Weng <wengzhe@xiaomi.com>
This commit is contained in:
Zhe Weng 2023-05-18 15:28:25 +08:00 committed by Alan Carvalho de Assis
parent 3930c70954
commit e7043828a7
1 changed files with 18 additions and 31 deletions
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49
libs/libc/netdb/lib_gethostentbynamer.c
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@ -576,10 +576,9 @@ static int lib_dns_lookup(FAR const char *name, FAR struct hostent_s *host,
#ifdef CONFIG_NETDB_HOSTFILE #ifdef CONFIG_NETDB_HOSTFILE
static int lib_hostfile_lookup(FAR const char *name, static int lib_hostfile_lookup(FAR const char *name,
FAR struct hostent_s *host, FAR char *buf, FAR struct hostent_s *host, FAR char *buf,
size_t buflen, FAR int *h_errnop) size_t buflen)
{ {
FAR FILE *stream; FAR FILE *stream;
int herrnocode;
int nread; int nread;
/* Search the hosts file for a match */ /* Search the hosts file for a match */
@ -591,10 +590,8 @@ static int lib_hostfile_lookup(FAR const char *name,
nerr("ERROR: Failed to open the hosts file %s: %d\n", nerr("ERROR: Failed to open the hosts file %s: %d\n",
CONFIG_NETDB_HOSTCONF_PATH, errcode); CONFIG_NETDB_HOSTCONF_PATH, errcode);
UNUSED(errcode);
herrnocode = NO_RECOVERY; return errcode;
goto errorout_with_herrnocode;
} }
/* Loop reading entries from the hosts file until a match is found or /* Loop reading entries from the hosts file until a match is found or
@ -620,8 +617,8 @@ static int lib_hostfile_lookup(FAR const char *name,
} }
else if (nread != -EAGAIN) else if (nread != -EAGAIN)
{ {
herrnocode = NO_RECOVERY; fclose(stream);
goto errorout_with_stream; return nread;
} }
} }
else if (nread > 0) else if (nread > 0)
@ -664,21 +661,11 @@ static int lib_hostfile_lookup(FAR const char *name,
while (nread != 0); while (nread != 0);
/* We get here when the end of the hosts file is encountered without /* We get here when the end of the hosts file is encountered without
* finding the hostname. * finding the hostname. Return 1 meaning that we have no errors but
* no match either.
*/ */
herrnocode = HOST_NOT_FOUND; return 1;
errorout_with_stream:
fclose(stream);
errorout_with_herrnocode:
if (h_errnop)
{
*h_errnop = herrnocode;
}
return ERROR;
} }
#endif /* CONFIG_NETDB_HOSTFILE */ #endif /* CONFIG_NETDB_HOSTFILE */
@ -756,6 +743,17 @@ int gethostentbyname_r(FAR const char *name,
} }
#endif #endif
#ifdef CONFIG_NETDB_HOSTFILE
/* Search the hosts file for a match */
if (lib_hostfile_lookup(name, host, buf, buflen) == 0)
{
/* Found the host in hosts file */
return OK;
}
#endif
/* Try to find the name in the HOSTALIASES environment variable */ /* Try to find the name in the HOSTALIASES environment variable */
#ifdef CONFIG_NETDB_DNSCLIENT #ifdef CONFIG_NETDB_DNSCLIENT
@ -780,23 +778,12 @@ int gethostentbyname_r(FAR const char *name,
} }
#endif /* CONFIG_NETDB_DNSCLIENT */ #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) if (h_errnop)
{ {
*h_errnop = HOST_NOT_FOUND; *h_errnop = HOST_NOT_FOUND;
} }
return ERROR; return ERROR;
#endif
} }
#endif /* CONFIG_LIBC_NETDB */ #endif /* CONFIG_LIBC_NETDB */