Permalink
Browse files

Added new feature (rfc2671)

  • Loading branch information...
1 parent e447bc5 commit 90364defb038d5d6b97acf9df9ed152d2393a863 hpopescu@ixiacom.com committed with bagder Aug 10, 2012
Showing with 366 additions and 185 deletions.
  1. +4 −0 Makefile.inc
  2. +12 −0 ares.h
  3. +79 −0 ares_create_query.3
  4. +209 −0 ares_create_query.c
  5. +4 −4 ares_dns.h
  6. +7 −0 ares_init.c
  7. +7 −0 ares_mkquery.3
  8. +1 −172 ares_mkquery.c
  9. +8 −0 ares_private.h
  10. +28 −5 ares_process.c
  11. +2 −2 ares_query.c
  12. +5 −2 ares_send.c
View
@@ -20,6 +20,7 @@ CSOURCES = ares__close_sockets.c \
ares_library_init.c \
ares_llist.c \
ares_mkquery.c \
+ ares_create_query.c \
ares_nowarn.c \
ares_options.c \
ares_parse_a_reply.c \
@@ -92,6 +93,7 @@ MANPAGES = ares_cancel.3 \
ares_library_cleanup.3 \
ares_library_init.3 \
ares_mkquery.3 \
+ ares_create_query.3 \
ares_parse_a_reply.3 \
ares_parse_aaaa_reply.3 \
ares_parse_mx_reply.3 \
@@ -133,6 +135,7 @@ HTMLPAGES = ares_cancel.html \
ares_library_cleanup.html \
ares_library_init.html \
ares_mkquery.html \
+ ares_create_query.html \
ares_parse_a_reply.html \
ares_parse_aaaa_reply.html \
ares_parse_mx_reply.html \
@@ -173,6 +176,7 @@ PDFPAGES = ares_cancel.pdf \
ares_library_cleanup.pdf \
ares_library_init.pdf \
ares_mkquery.pdf \
+ ares_create_query.pdf \
ares_parse_a_reply.pdf \
ares_parse_aaaa_reply.pdf \
ares_parse_mx_reply.pdf \
View
12 ares.h
@@ -143,6 +143,7 @@ extern "C" {
#define ARES_FLAG_NOSEARCH (1 << 5)
#define ARES_FLAG_NOALIASES (1 << 6)
#define ARES_FLAG_NOCHECKRESP (1 << 7)
+#define ARES_FLAG_EDNS (1 << 8)
/* Option mask values */
#define ARES_OPT_FLAGS (1 << 0)
@@ -160,6 +161,7 @@ extern "C" {
#define ARES_OPT_SOCK_RCVBUF (1 << 12)
#define ARES_OPT_TIMEOUTMS (1 << 13)
#define ARES_OPT_ROTATE (1 << 14)
+#define ARES_OPT_EDNSPSZ (1 << 15)
/* Nameinfo flag values */
#define ARES_NI_NOFQDN (1 << 0)
@@ -265,6 +267,7 @@ struct ares_options {
void *sock_state_cb_data;
struct apattern *sortlist;
int nsort;
+ int ednspsz;
};
struct hostent;
@@ -403,6 +406,15 @@ CARES_EXTERN void ares_process_fd(ares_channel channel,
ares_socket_t read_fd,
ares_socket_t write_fd);
+CARES_EXTERN 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);
+
CARES_EXTERN int ares_mkquery(const char *name,
int dnsclass,
int type,
View
@@ -0,0 +1,79 @@
+.\"
+.\" Copyright 1998, 2000 by the Massachusetts Institute of Technology.
+.\"
+.\" Permission to use, copy, modify, and distribute this
+.\" software and its documentation for any purpose and without
+.\" fee is hereby granted, provided that the above copyright
+.\" notice appear in all copies and that both that copyright
+.\" notice and this permission notice appear in supporting
+.\" documentation, and that the name of M.I.T. not be used in
+.\" advertising or publicity pertaining to distribution of the
+.\" software without specific, written prior permission.
+.\" M.I.T. makes no representations about the suitability of
+.\" this software for any purpose. It is provided "as is"
+.\" without express or implied warranty.
+.\"
+.TH ARES_CREATE_QUERY 3 "20 Nov 2009"
+.SH NAME
+ares_create_query \- Compose a single-question DNS query buffer
+.SH SYNOPSIS
+.nf
+.B #include <ares.h>
+.PP
+.B int ares_create_query(const char *\fIname\fP, int \fIdnsclass\fP,\
+ int \fItype\fP,
+.B unsigned short \fIid\fP, int \fIrd\fP,\
+ unsigned char **\fIbuf\fP,
+.B int *\fIbuflen\fP, int \fImax_udp_size\fP)
+.fi
+.SH DESCRIPTION
+The
+.B ares_create_query
+function composes a DNS query with a single question.
+The parameter
+.I name
+gives the query name as a NUL-terminated C string of period-separated
+labels optionally ending with a period; periods and backslashes within
+a label must be escaped with a backlash. The parameters
+.I dnsclass
+and
+.I type
+give the class and type of the query using the values defined in
+.BR <arpa/nameser.h> .
+The parameter
+.I id
+gives a 16-bit identifier for the query. The parameter
+.I rd
+should be nonzero if recursion is desired, zero if not. The query
+will be placed in an allocated buffer, a pointer to which will be
+stored in the variable pointed to by
+.IR buf ,
+and the length of which will be stored in the variable pointed to by
+.IR buflen .
+It is the caller's responsibility to free this buffer using
+\fIares_free_string(3)\fP when it is no longer needed.
+The parameter
+.I max_udp_size
+should be nonzero to activate EDNS. Usage of \fIares_create_query(3)\fP\ with
+.I max_udp_size
+set to zero is equivalent to \fIares_mkquery(3)\fP.
+.SH RETURN VALUES
+.B ares_create_query
+can return any of the following values:
+.TP 15
+.B ARES_SUCCESS
+Construction of the DNS query succeeded.
+.TP 15
+.B ARES_EBADNAME
+The query name
+.I name
+could not be encoded as a domain name, either because it contained a
+zero-length label or because it contained a label of more than 63
+characters.
+.TP 15
+.B ARES_ENOMEM
+Memory was exhausted.
+.SH SEE ALSO
+.BR ares_expand_name (3),
+.BR ares_free_string (3)
+.SH AUTHOR
View
@@ -0,0 +1,209 @@
+
+/* Copyright 1998 by the Massachusetts Institute of Technology.
+ *
+ * Permission to use, copy, modify, and distribute this
+ * software and its documentation for any purpose and without
+ * fee is hereby granted, provided that the above copyright
+ * notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting
+ * documentation, and that the name of M.I.T. not be used in
+ * advertising or publicity pertaining to distribution of the
+ * software without specific, written prior permission.
+ * M.I.T. makes no representations about the suitability of
+ * this software for any purpose. It is provided "as is"
+ * without express or implied warranty.
+ */
+
+#include "ares_setup.h"
+
+#ifdef HAVE_SYS_SOCKET_H
+# include <sys/socket.h>
+#endif
+#ifdef HAVE_NETINET_IN_H
+# include <netinet/in.h>
+#endif
+#ifdef HAVE_ARPA_NAMESER_H
+# include <arpa/nameser.h>
+#else
+# include "nameser.h"
+#endif
+#ifdef HAVE_ARPA_NAMESER_COMPAT_H
+# include <arpa/nameser_compat.h>
+#endif
+
+#include <stdlib.h>
+#include <string.h>
+#include "ares.h"
+#include "ares_dns.h"
+#include "ares_private.h"
+
+/* Header format, from RFC 1035:
+ * 1 1 1 1 1 1
+ * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+ * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ * | ID |
+ * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ * |QR| Opcode |AA|TC|RD|RA| Z | RCODE |
+ * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ * | QDCOUNT |
+ * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ * | ANCOUNT |
+ * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ * | NSCOUNT |
+ * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ * | ARCOUNT |
+ * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ *
+ * AA, TC, RA, and RCODE are only set in responses. Brief description
+ * of the remaining fields:
+ * ID Identifier to match responses with queries
+ * QR Query (0) or response (1)
+ * Opcode For our purposes, always QUERY
+ * RD Recursion desired
+ * Z Reserved (zero)
+ * QDCOUNT Number of queries
+ * ANCOUNT Number of answers
+ * NSCOUNT Number of name server records
+ * ARCOUNT Number of additional records
+ *
+ * Question format, from RFC 1035:
+ * 1 1 1 1 1 1
+ * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+ * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ * | |
+ * / QNAME /
+ * / /
+ * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ * | QTYPE |
+ * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ * | QCLASS |
+ * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ *
+ * The query name is encoded as a series of labels, each represented
+ * as a one-byte length (maximum 63) followed by the text of the
+ * label. The list is terminated by a label of length zero (which can
+ * be thought of as the root domain).
+ */
+
+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, ns_t_opt);
+ DNS_RR_SET_CLASS(q, max_udp_size);
+ }
+
+ return ARES_SUCCESS;
+}
View
@@ -95,9 +95,9 @@
#define DNS_RR_LEN(r) DNS__16BIT((r) + 8)
/* Macros for constructing the fixed part of a DNS resource record */
-#define DNS_RR_SET_TYPE(r) DNS__SET16BIT(r, v)
-#define DNS_RR_SET_CLASS(r) DNS__SET16BIT((r) + 2, v)
-#define DNS_RR_SET_TTL(r) DNS__SET32BIT((r) + 4, v)
-#define DNS_RR_SET_LEN(r) DNS__SET16BIT((r) + 8, v)
+#define DNS_RR_SET_TYPE(r, v) DNS__SET16BIT(r, v)
+#define DNS_RR_SET_CLASS(r, v) DNS__SET16BIT((r) + 2, v)
+#define DNS_RR_SET_TTL(r, v) DNS__SET32BIT((r) + 4, v)
+#define DNS_RR_SET_LEN(r, v) DNS__SET16BIT((r) + 8, v)
#endif /* HEADER_CARES_DNS_H */
Oops, something went wrong.

0 comments on commit 90364de

Please sign in to comment.