void ares_gethostbyname(ares_channel channel, const char *name, int family,
ares_host_callback callback, void *arg)
{
struct host_query *hquery;
/* Right now we only know how to look up Internet addresses - and unspec
means try both basically. */
switch (family) {
case AF_INET:
case AF_INET6:
case AF_UNSPEC:
break;
default:
callback(arg, ARES_ENOTIMP, 0, NULL);
return;
}
if (fake_hostent(name, family, callback, arg))
return;
/* Allocate and fill in the host query structure. */
hquery = ares_malloc(sizeof(struct host_query));
if (!hquery)
{
callback(arg, ARES_ENOMEM, 0, NULL);
return;
}
hquery->channel = channel;
hquery->name = ares_strdup(name);
hquery->want_family = family;
hquery->sent_family = -1; /* nothing is sent yet */
if (!hquery->name) {
ares_free(hquery);
callback(arg, ARES_ENOMEM, 0, NULL);
return;
}
hquery->callback = callback;
hquery->arg = arg;
hquery->remaining_lookups = channel->lookups;
hquery->timeouts = 0;
/* Start performing lookups according to channel->lookups. */
next_lookup(hquery, ARES_ECONNREFUSED /* initial error code */);
}
/* If the name looks like an IP address, fake up a host entry, end the
* query immediately, and return true. Otherwise return false.
*/
static int fake_hostent(const char *name, int family,
ares_host_callback callback, void *arg)
{
struct hostent hostent;
char *aliases[1] = { NULL };
char *addrs[2];
int result = 0;
struct in_addr in;
struct ares_in6_addr in6;
if (family == AF_INET || family == AF_INET6)
{
/* It only looks like an IP address if it's all numbers and dots. */
int numdots = 0, valid = 1;
const char *p;
for (p = name; *p; p++)
{
if (!ISDIGIT(*p) && *p != '.') {
valid = 0;
break;
} else if (*p == '.') {
numdots++;
}
}
/* if we don't have 3 dots, it is illegal
* (although inet_addr doesn't think so).
*/
if (numdots != 3 || !valid)
result = 0;
else
result = ((in.s_addr = inet_addr(name)) == INADDR_NONE ? 0 : 1);
if (result)
family = AF_INET;
}
if (family == AF_INET6)
result = (ares_inet_pton(AF_INET6, name, &in6) < 1 ? 0 : 1);
if (!result)
return 0;
if (family == AF_INET)
{
hostent.h_length = (int)sizeof(struct in_addr);
addrs[0] = (char *)∈
}
else if (family == AF_INET6)
{
hostent.h_length = (int)sizeof(struct ares_in6_addr);
addrs[0] = (char *)&in6;
}
/* Duplicate the name, to avoid a constness violation. */
hostent.h_name = ares_strdup(name);
if (!hostent.h_name)
{
callback(arg, ARES_ENOMEM, 0, NULL);
return 1;
}
/* Fill in the rest of the host structure and terminate the query. */
addrs[1] = NULL;
hostent.h_aliases = aliases;
hostent.h_addrtype = aresx_sitoss(family);
hostent.h_addr_list = addrs;
callback(arg, ARES_SUCCESS, 0, &hostent);
ares_free((char *)(hostent.h_name));
return 1;
}
void ares_search(ares_channel channel, const char *name, int dnsclass,
int type, ares_callback callback, void *arg)
{
struct search_query *squery;
char *s;
const char *p;
int status, ndots;
/* If name only yields one domain to search, then we don't have
* to keep extra state, so just do an ares_query().
*/
status = single_domain(channel, name, &s);
if (status != ARES_SUCCESS)
{
callback(arg, status, 0, NULL, 0);
return;
}
if (s)
{
ares_query(channel, s, dnsclass, type, callback, arg);
ares_free(s);
return;
}
/* Allocate a search_query structure to hold the state necessary for
* doing multiple lookups.
*/
squery = ares_malloc(sizeof(struct search_query));
if (!squery)
{
callback(arg, ARES_ENOMEM, 0, NULL, 0);
return;
}
squery->channel = channel;
squery->name = ares_strdup(name);
if (!squery->name)
{
ares_free(squery);
callback(arg, ARES_ENOMEM, 0, NULL, 0);
return;
}
squery->dnsclass = dnsclass;
squery->type = type;
squery->status_as_is = -1;
squery->callback = callback;
squery->arg = arg;
squery->timeouts = 0;
squery->ever_got_nodata = 0;
/* Count the number of dots in name. */
ndots = 0;
for (p = name; *p; p++)
{
if (*p == '.')
ndots++;
}
/* If ndots is at least the channel ndots threshold (usually 1),
* then we try the name as-is first. Otherwise, we try the name
* as-is last.
*/
if (ndots >= channel->ndots)
{
/* Try the name as-is first. */
squery->next_domain = 0;
squery->trying_as_is = 1;
ares_query(channel, name, dnsclass, type, search_callback, squery);
}
else
{
/* Try the name as-is last; start with the first search domain. */
squery->next_domain = 1;
squery->trying_as_is = 0;
status = cat_domain(name, channel->domains[0], &s);
if (status == ARES_SUCCESS)
{
ares_query(channel, s, dnsclass, type, search_callback, squery);
ares_free(s);
}
else
{
/* failed, free the malloc()ed memory */
ares_free(squery->name);
ares_free(squery);
callback(arg, status, 0, NULL, 0);
}
}
}
int ares__get_hostent(FILE *fp, int family, struct hostent **host)
{
char *line = NULL, *p, *q, **alias;
char *txtaddr, *txthost, *txtalias;
int status;
size_t addrlen, linesize, naliases;
struct ares_addr addr;
struct hostent *hostent = NULL;
*host = NULL; /* Assume failure */
/* Validate family */
switch (family) {
case AF_INET:
case AF_INET6:
case AF_UNSPEC:
break;
default:
return ARES_EBADFAMILY;
}
while ((status = ares__read_line(fp, &line, &linesize)) == ARES_SUCCESS)
{
/* Trim line comment. */
p = line;
while (*p && (*p != '#'))
p++;
*p = '\0';
/* Trim trailing whitespace. */
q = p - 1;
while ((q >= line) && ISSPACE(*q))
q--;
*++q = '\0';
/* Skip leading whitespace. */
p = line;
while (*p && ISSPACE(*p))
p++;
if (!*p)
/* Ignore line if empty. */
continue;
/* Pointer to start of IPv4 or IPv6 address part. */
txtaddr = p;
/* Advance past address part. */
while (*p && !ISSPACE(*p))
p++;
if (!*p)
/* Ignore line if reached end of line. */
continue;
/* Null terminate address part. */
*p = '\0';
/* Advance to host name */
p++;
while (*p && ISSPACE(*p))
p++;
if (!*p)
/* Ignore line if reached end of line. */
continue; /* LCOV_EXCL_LINE: trailing whitespace already stripped */
/* Pointer to start of host name. */
txthost = p;
/* Advance past host name. */
while (*p && !ISSPACE(*p))
p++;
/* Pointer to start of first alias. */
txtalias = NULL;
if (*p)
{
q = p + 1;
while (*q && ISSPACE(*q))
q++;
if (*q)
txtalias = q;
}
/* Null terminate host name. */
*p = '\0';
/* find out number of aliases. */
naliases = 0;
if (txtalias)
{
p = txtalias;
while (*p)
{
while (*p && !ISSPACE(*p))
p++;
while (*p && ISSPACE(*p))
p++;
naliases++;
}
}
/* Convert address string to network address for the requested family. */
addrlen = 0;
addr.family = AF_UNSPEC;
addr.addrV4.s_addr = INADDR_NONE;
if ((family == AF_INET) || (family == AF_UNSPEC))
{
addr.addrV4.s_addr = inet_addr(txtaddr);
if (addr.addrV4.s_addr != INADDR_NONE)
{
/* Actual network address family and length. */
addr.family = AF_INET;
addrlen = sizeof(addr.addrV4);
}
}
if ((family == AF_INET6) || ((family == AF_UNSPEC) && (!addrlen)))
{
if (ares_inet_pton(AF_INET6, txtaddr, &addr.addrV6) > 0)
{
/* Actual network address family and length. */
addr.family = AF_INET6;
addrlen = sizeof(addr.addrV6);
}
}
if (!addrlen)
/* Ignore line if invalid address string for the requested family. */
continue;
/*
** Actual address family possible values are AF_INET and AF_INET6 only.
*/
/* Allocate memory for the hostent structure. */
hostent = ares_malloc(sizeof(struct hostent));
if (!hostent)
break;
/* Initialize fields for out of memory condition. */
hostent->h_aliases = NULL;
hostent->h_addr_list = NULL;
/* Copy official host name. */
hostent->h_name = ares_strdup(txthost);
if (!hostent->h_name)
break;
/* Copy network address. */
hostent->h_addr_list = ares_malloc(2 * sizeof(char *));
if (!hostent->h_addr_list)
break;
hostent->h_addr_list[1] = NULL;
hostent->h_addr_list[0] = ares_malloc(addrlen);
if (!hostent->h_addr_list[0])
break;
if (addr.family == AF_INET)
memcpy(hostent->h_addr_list[0], &addr.addrV4, sizeof(addr.addrV4));
else
memcpy(hostent->h_addr_list[0], &addr.addrV6, sizeof(addr.addrV6));
/* Copy aliases. */
hostent->h_aliases = ares_malloc((naliases + 1) * sizeof(char *));
if (!hostent->h_aliases)
break;
alias = hostent->h_aliases;
while (naliases)
*(alias + naliases--) = NULL;
*alias = NULL;
while (txtalias)
{
p = txtalias;
while (*p && !ISSPACE(*p))
p++;
q = p;
while (*q && ISSPACE(*q))
q++;
*p = '\0';
if ((*alias = ares_strdup(txtalias)) == NULL)
break;
alias++;
txtalias = *q ? q : NULL;
}
if (txtalias)
/* Alias memory allocation failure. */
break;
/* Copy actual network address family and length. */
hostent->h_addrtype = aresx_sitoss(addr.family);
hostent->h_length = aresx_uztoss(addrlen);
/* Free line buffer. */
ares_free(line);
/* Return hostent successfully */
*host = hostent;
return ARES_SUCCESS;
}
/* If allocated, free line buffer. */
if (line)
ares_free(line);
if (status == ARES_SUCCESS)
{
/* Memory allocation failure; clean up. */
if (hostent)
{
if (hostent->h_name)
ares_free((char *) hostent->h_name);
if (hostent->h_aliases)
{
for (alias = hostent->h_aliases; *alias; alias++)
ares_free(*alias);
ares_free(hostent->h_aliases);
}
if (hostent->h_addr_list)
{
if (hostent->h_addr_list[0])
ares_free(hostent->h_addr_list[0]);
ares_free(hostent->h_addr_list);
}
ares_free(hostent);
}
return ARES_ENOMEM;
}
return status;
}
/* Determine if this name only yields one query. If it does, set *s to
* the string we should query, in an allocated buffer. If not, set *s
* to NULL.
*/
STATIC_TESTABLE int single_domain(ares_channel channel, const char *name, char **s)
{
size_t len = strlen(name);
const char *hostaliases;
FILE *fp;
char *line = NULL;
int status;
size_t linesize;
const char *p, *q;
int error;
/* If the name contains a trailing dot, then the single query is the name
* sans the trailing dot.
*/
if ((len > 0) && (name[len - 1] == '.'))
{
*s = ares_strdup(name);
return (*s) ? ARES_SUCCESS : ARES_ENOMEM;
}
if (!(channel->flags & ARES_FLAG_NOALIASES) && !strchr(name, '.'))
{
/* The name might be a host alias. */
hostaliases = getenv("HOSTALIASES");
if (hostaliases)
{
fp = fopen(hostaliases, "r");
if (fp)
{
while ((status = ares__read_line(fp, &line, &linesize))
== ARES_SUCCESS)
{
if (strncasecmp(line, name, len) != 0 ||
!ISSPACE(line[len]))
continue;
p = line + len;
while (ISSPACE(*p))
p++;
if (*p)
{
q = p + 1;
while (*q && !ISSPACE(*q))
q++;
*s = ares_malloc(q - p + 1);
if (*s)
{
memcpy(*s, p, q - p);
(*s)[q - p] = 0;
}
ares_free(line);
fclose(fp);
return (*s) ? ARES_SUCCESS : ARES_ENOMEM;
}
}
ares_free(line);
fclose(fp);
if (status != ARES_SUCCESS && status != ARES_EOF)
return status;
}
else
{
error = ERRNO;
switch(error)
{
case ENOENT:
case ESRCH:
break;
default:
DEBUGF(fprintf(stderr, "fopen() failed with error: %d %s\n",
error, strerror(error)));
DEBUGF(fprintf(stderr, "Error opening file: %s\n",
hostaliases));
*s = NULL;
return ARES_EFILE;
}
}
}
}
if (channel->flags & ARES_FLAG_NOSEARCH || channel->ndomains == 0)
{
/* No domain search to do; just try the name as-is. */
*s = ares_strdup(name);
return (*s) ? ARES_SUCCESS : ARES_ENOMEM;
}
*s = NULL;
return ARES_SUCCESS;
}
