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netdb: Truncate the list of ips instead of bailing out with ERANGE

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In many cases, users only care the first address anyway.
This commit is contained in:
YAMAMOTO Takashi 2020-05-15 13:43:34 +09:00 committed by Xiang Xiao
parent b36420ef32
commit e783a59f9d
1 changed files with 8 additions and 15 deletions
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23
libs/libc/netdb/lib_gethostentbynamer.c
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@ -487,9 +487,12 @@ static int lib_dns_lookup(FAR const char *name, FAR struct hostent_s *host,
/* 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.
*/
if (buflen <= sizeof(struct hostent_info_s))
namelen = strlen(name);
if (buflen < sizeof(struct hostent_info_s) - 1 + sizeof(union dns_addr_u) +
namelen + 1)
{
return -ERANGE;
}
@ -500,13 +503,6 @@ static int lib_dns_lookup(FAR const char *name, FAR struct hostent_s *host,
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));
@ -516,7 +512,8 @@ static int lib_dns_lookup(FAR const char *name, FAR struct hostent_s *host,
/* Try to get the host address using the DNS name server */
naddr = buflen / sizeof(union dns_addr_u);
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)
{
@ -555,18 +552,14 @@ static int lib_dns_lookup(FAR const char *name, FAR struct hostent_s *host,
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 */
namelen = strlen(name);
if ((namelen + 1) > buflen)
{
return -ERANGE;
}
DEBUGASSERT(buflen >= namelen + 1);
strncpy(ptr, name, buflen);
/* Set the address to h_name */