int ares_create_query(const char *name, int dnsclass, int type,
unsigned short id, int rd, unsigned char **buf,
int *buflen, int max_udp_size)
{
int len;
unsigned char *q;
const char *p;
/* Set our results early, in case we bail out early with an error. */
*buflen = 0;
*buf = NULL;
/* Compute the length of the encoded name so we can check buflen.
* Start counting at 1 for the zero-length label at the end. */
len = 1;
for (p = name; *p; p++)
{
if (*p == '\\' && *(p + 1) != 0)
p++;
len++;
}
/* If there are n periods in the name, there are n + 1 labels, and
* thus n + 1 length fields, unless the name is empty or ends with a
* period. So add 1 unless name is empty or ends with a period.
*/
if (*name && *(p - 1) != '.')
len++;
/* Immediately reject names that are longer than the maximum of 255
* bytes that's specified in RFC 1035 ("To simplify implementations,
* the total length of a domain name (i.e., label octets and label
* length octets) is restricted to 255 octets or less."). We aren't
* doing this just to be a stickler about RFCs. For names that are
* too long, 'dnscache' closes its TCP connection to us immediately
* (when using TCP) and ignores the request when using UDP, and
* BIND's named returns ServFail (TCP or UDP). Sending a request
* that we know will cause 'dnscache' to close the TCP connection is
* painful, since that makes any other outstanding requests on that
* connection fail. And sending a UDP request that we know
* 'dnscache' will ignore is bad because resources will be tied up
* until we time-out the request.
*/
if (len > MAXCDNAME)
return ARES_EBADNAME;
*buflen = len + HFIXEDSZ + QFIXEDSZ + (max_udp_size ? EDNSFIXEDSZ : 0);
*buf = malloc(*buflen);
if (!*buf)
return ARES_ENOMEM;
/* Set up the header. */
q = *buf;
memset(q, 0, HFIXEDSZ);
DNS_HEADER_SET_QID(q, id);
DNS_HEADER_SET_OPCODE(q, QUERY);
if (rd) {
DNS_HEADER_SET_RD(q, 1);
}
else {
DNS_HEADER_SET_RD(q, 0);
}
DNS_HEADER_SET_QDCOUNT(q, 1);
if (max_udp_size) {
DNS_HEADER_SET_ARCOUNT(q, 1);
}
/* A name of "." is a screw case for the loop below, so adjust it. */
if (strcmp(name, ".") == 0)
name++;
/* Start writing out the name after the header. */
q += HFIXEDSZ;
while (*name)
{
if (*name == '.')
return ARES_EBADNAME;
/* Count the number of bytes in this label. */
len = 0;
for (p = name; *p && *p != '.'; p++)
{
if (*p == '\\' && *(p + 1) != 0)
p++;
len++;
}
if (len > MAXLABEL)
return ARES_EBADNAME;
/* Encode the length and copy the data. */
*q++ = (unsigned char)len;
for (p = name; *p && *p != '.'; p++)
{
if (*p == '\\' && *(p + 1) != 0)
p++;
*q++ = *p;
}
/* Go to the next label and repeat, unless we hit the end. */
if (!*p)
break;
name = p + 1;
}
/* Add the zero-length label at the end. */
*q++ = 0;
/* Finish off the question with the type and class. */
DNS_QUESTION_SET_TYPE(q, type);
DNS_QUESTION_SET_CLASS(q, dnsclass);
if (max_udp_size)
{
q += QFIXEDSZ;
memset(q, 0, EDNSFIXEDSZ);
q++;
DNS_RR_SET_TYPE(q, T_OPT);
DNS_RR_SET_CLASS(q, max_udp_size);
}
return ARES_SUCCESS;
}
int ares_mkquery(const char *name, int dnsclass, int type, unsigned short id,
int rd, unsigned char **buf, int *buflen)
{
int len;
unsigned char *q;
const char *p;
/* Compute the length of the encoded name so we can check buflen.
* Start counting at 1 for the zero-length label at the end. */
len = 1;
for (p = name; *p; p++)
{
if (*p == '\\' && *(p + 1) != 0)
p++;
len++;
}
/* If there are n periods in the name, there are n + 1 labels, and
* thus n + 1 length fields, unless the name is empty or ends with a
* period. So add 1 unless name is empty or ends with a period.
*/
if (*name && *(p - 1) != '.')
len++;
*buflen = len + HFIXEDSZ + QFIXEDSZ;
*buf = malloc(*buflen);
if (!*buf)
return ARES_ENOMEM;
/* Set up the header. */
q = *buf;
memset(q, 0, HFIXEDSZ);
DNS_HEADER_SET_QID(q, id);
DNS_HEADER_SET_OPCODE(q, QUERY);
DNS_HEADER_SET_RD(q, (rd) ? 1 : 0);
DNS_HEADER_SET_QDCOUNT(q, 1);
/* A name of "." is a screw case for the loop below, so adjust it. */
if (strcmp(name, ".") == 0)
name++;
/* Start writing out the name after the header. */
q += HFIXEDSZ;
while (*name)
{
if (*name == '.')
return ARES_EBADNAME;
/* Count the number of bytes in this label. */
len = 0;
for (p = name; *p && *p != '.'; p++)
{
if (*p == '\\' && *(p + 1) != 0)
p++;
len++;
}
if (len > MAXLABEL)
return ARES_EBADNAME;
/* Encode the length and copy the data. */
*q++ = len;
for (p = name; *p && *p != '.'; p++)
{
if (*p == '\\' && *(p + 1) != 0)
p++;
*q++ = *p;
}
/* Go to the next label and repeat, unless we hit the end. */
if (!*p)
break;
name = p + 1;
}
/* Add the zero-length label at the end. */
*q++ = 0;
/* Finish off the question with the type and class. */
DNS_QUESTION_SET_TYPE(q, type);
DNS_QUESTION_SET_CLASS(q, dnsclass);
return ARES_SUCCESS;
}
int evdns_make_query(char *domain, int dnsclass, int type,
unsigned int id, int rd, unsigned char *buf)
{
unsigned char *p = NULL, *q = NULL, *s = NULL, *name = NULL;
int buflen = 0, len = 0;
if(domain)
{
p = name = (unsigned char *)domain;
while(*p != '\0')
{
if(*p++ != '\\')++len;
}
if(*(p-1) != '.') ++len;
//add end \0 size
len++;
if(len > MAXCDNAME) return -1;
buflen = len + HFIXEDSZ + QFIXEDSZ;
q = buf;
memset(q, 0, buflen);
DNS_HEADER_SET_QID(q, id);
DNS_HEADER_SET_OPCODE(q, 0);
if(rd)
{
DNS_HEADER_SET_RD(q, 1);
}
else
{
DNS_HEADER_SET_RD(q, 0);
}
DNS_HEADER_SET_QDCOUNT(q, 1);
if (*name == '.' && *(name + 1) == '\0') name++;
/* Start writing out the name after the header. */
q += HFIXEDSZ;
p = name;
//fprintf(stdout, "%d:dnsquery:%d:%d\n", __LINE__, (q - buf), buflen);
do
{
s = q++;
len = 0;
while(*p != '.' && *p != '\0')
{
if (*p == '\\') ++p;
else{*q++ = *p++; len++;}
}
*s = (unsigned char)len;
if(*p != '\0')++p;
}while(*p != '\0');
*q++ = 0;
/* Finish off the question with the type and class. */
DNS_QUESTION_SET_TYPE(q, type);
DNS_QUESTION_SET_CLASS(q, dnsclass);
/*
if((tmpfd = open("/tmp/buf.txt", O_CREAT|O_RDWR, 0644)) > 0)
{
write(tmpfd, buf, buflen);
close(tmpfd);
}
fprintf(stdout, "%d:dnsquery:%d:%d\n", __LINE__, (q - buf), buflen);
*/
return buflen;
}
return 0;
}