Correctly handle the case of the root showing up as a name in a DNS
request or reply. (Redid "get_dns_name()" along the lines of the code in the BSD resolver.) Add code to dissect SOA RRs. svn path=/trunk/; revision=297
This commit is contained in:
Guy Harris
parent
5f99945363
commit
cf84edfcf4
244
packet-dns.c
244
packet-dns.c
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@ -1,7 +1,7 @@
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/* packet-dns.c
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* Routines for DNS packet disassembly
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*
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* $Id: packet-dns.c,v 1.17 1999/03/23 03:14:36 gram Exp $
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* $Id: packet-dns.c,v 1.18 1999/05/27 05:35:07 guy Exp $
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*
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* Ethereal - Network traffic analyzer
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* By Gerald Combs <gerald@zing.org>
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@ -287,100 +287,77 @@ dns_class_name(int class)
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return class_name;
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}
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static int
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is_compressed_name(const u_char *foo)
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{
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return (0xc0 == (*foo & 0xc0));
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}
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static int
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get_compressed_name_offset(const u_char *ptr)
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{
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return ((*ptr & ~0xc0) << 8) | *(ptr+1);
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}
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static int
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copy_one_name_component(const u_char *dataptr, char *nameptr)
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{
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int len;
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int n;
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len = n = *dataptr++;
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if (0 == len)
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return 0;
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while (n-- > 0)
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*nameptr++ = *dataptr++;
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return len;
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}
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static int
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copy_name_component_rec(const u_char *dns_data_ptr, const u_char *dataptr,
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char *nameptr, int *real_string_len)
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{
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int len = 0;
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int str_len;
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int offset;
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int compress = 0;
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if (is_compressed_name(dataptr)) {
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compress = 1;
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offset = get_compressed_name_offset(dataptr);
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dataptr = dns_data_ptr + offset;
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copy_name_component_rec(dns_data_ptr, dataptr, nameptr, &str_len);
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*real_string_len += str_len;
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nameptr += str_len;
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len = 2;
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}
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else {
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str_len = copy_one_name_component(dataptr, nameptr);
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*real_string_len = str_len;
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dataptr += str_len + 1;
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len += str_len + 1;
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nameptr += str_len;
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}
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if (compress)
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return len;
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(*real_string_len)++;
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if (*dataptr > 0) {
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*nameptr++ = '.';
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len += copy_name_component_rec(dns_data_ptr, dataptr, nameptr, &str_len);
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*real_string_len += str_len;
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return len;
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}
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return len + 1;
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}
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int
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get_dns_name(const u_char *dns_data_ptr, const u_char *pd, int offset,
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char *nameptr, int maxname)
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get_dns_name(const u_char *dns_data_ptr, const u_char *dptr, char *name,
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int maxname)
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{
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int len;
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const u_char *dataptr = pd + offset;
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int str_len = 0;
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const u_char *dp = dptr;
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char *np = name;
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int len = -1;
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u_int component_len;
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int offset;
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memset (nameptr, 0, maxname);
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len = copy_name_component_rec(dns_data_ptr, dataptr, nameptr, &str_len);
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maxname--; /* reserve space for the trailing '\0' */
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while ((component_len = *dp++) != 0) {
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switch (component_len & 0xc0) {
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case 0x00:
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/* Label */
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if (np != name) {
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/* Not the first component - put in a '.'. */
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if (maxname > 0) {
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*np++ = '.';
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maxname--;
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}
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}
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while (component_len > 0) {
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if (maxname > 0) {
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*np++ = *dp;
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maxname--;
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}
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component_len--;
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dp++;
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}
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break;
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case 0x40:
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case 0x80:
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goto error; /* error */
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case 0xc0:
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/* Pointer. */
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/* XXX - check to make sure we aren't looping, by keeping track
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of how many characters are in the DNS packet, and of how many
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characters we've looked at, and quitting if the latter
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becomes bigger than the former. */
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offset = ((component_len & ~0xc0) << 8) | *dp++;
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/* If "len" is negative, we are still working on the original name,
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not something pointed to by a pointer, and so we should set "len"
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to the length of the original name. */
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if (len < 0)
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len = dp - dptr;
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dp = dns_data_ptr + offset;
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break; /* now continue processing from there */
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}
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}
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error:
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*np = '\0';
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/* If "len" is negative, we haven't seen a pointer, and thus haven't
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set the length, so set it. */
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if (len < 0)
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len = dp - dptr;
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/* Zero-length name means "root server" */
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if (*name == '\0')
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strcpy(name, "<Root>");
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return len;
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}
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static int
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get_dns_name_type_class (const u_char *dns_data_ptr,
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const u_char *pd,
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int offset,
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const u_char *dptr,
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char *name_ret,
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int *name_len_ret,
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int *type_ret,
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@ -391,24 +368,23 @@ get_dns_name_type_class (const u_char *dns_data_ptr,
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int type;
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int class;
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char name[MAXDNAME];
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const u_char *pd_save;
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const u_char *dptr_save;
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name_len = get_dns_name(dns_data_ptr, pd, offset, name, sizeof(name));
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pd += offset;
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pd_save = pd;
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pd += name_len;
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name_len = get_dns_name(dns_data_ptr, dptr, name, sizeof(name));
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dptr_save = dptr;
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dptr += name_len;
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type = pntohs(pd);
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pd += 2;
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class = pntohs(pd);
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pd += 2;
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type = pntohs(dptr);
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dptr += 2;
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class = pntohs(dptr);
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dptr += 2;
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strcpy (name_ret, name);
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*type_ret = type;
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*class_ret = class;
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*name_len_ret = name_len;
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len = pd - pd_save;
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len = dptr - dptr_save;
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return len;
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}
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@ -432,7 +408,7 @@ dissect_dns_query(const u_char *dns_data_ptr, const u_char *pd, int offset,
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data_start = dptr = pd + offset;
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len = get_dns_name_type_class(dns_data_ptr, pd, offset, name, &name_len,
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len = get_dns_name_type_class(dns_data_ptr, dptr, name, &name_len,
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&type, &class);
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dptr += len;
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@ -498,10 +474,11 @@ dissect_dns_answer(const u_char *dns_data_ptr, const u_char *pd, int offset,
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u_short data_len;
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proto_tree *rr_tree;
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proto_item *trr;
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const u_char *rrptr;
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data_start = dptr = pd + offset;
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len = get_dns_name_type_class(dns_data_ptr, pd, offset, name, &name_len,
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len = get_dns_name_type_class(dns_data_ptr, dptr, name, &name_len,
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&type, &class);
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dptr += len;
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@ -516,7 +493,7 @@ dissect_dns_answer(const u_char *dns_data_ptr, const u_char *pd, int offset,
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dptr += 2;
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switch (type) {
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case T_A: /* "A" record */
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case T_A:
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trr = proto_tree_add_item(dns_tree, offset, (dptr - data_start) + data_len,
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"%s: type %s, class %s, addr %s",
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name, type_name, class_name,
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@ -528,12 +505,12 @@ dissect_dns_answer(const u_char *dns_data_ptr, const u_char *pd, int offset,
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ip_to_str((guint8 *)dptr));
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break;
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case T_NS: /* "NS" record */
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case T_NS:
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{
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char ns_name[MAXDNAME];
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int ns_name_len;
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ns_name_len = get_dns_name(dns_data_ptr, dptr, 0, ns_name, sizeof(ns_name));
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ns_name_len = get_dns_name(dns_data_ptr, dptr, ns_name, sizeof(ns_name));
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trr = proto_tree_add_item(dns_tree, offset, (dptr - data_start) + data_len,
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"%s: type %s, class %s, ns %s",
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name, type_name, class_name, ns_name);
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@ -544,35 +521,90 @@ dissect_dns_answer(const u_char *dns_data_ptr, const u_char *pd, int offset,
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}
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break;
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case T_CNAME: /* "CNAME" record */
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case T_CNAME:
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{
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char cname[MAXDNAME];
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int cname_len;
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cname_len = get_dns_name(dns_data_ptr, dptr, 0, cname, sizeof(cname));
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cname_len = get_dns_name(dns_data_ptr, dptr, cname, sizeof(cname));
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trr = proto_tree_add_item(dns_tree, offset, (dptr - data_start) + data_len,
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"%s: type %s, class %s, cname %s",
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name, type_name, class_name, cname);
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rr_tree = add_rr_to_tree(trr, ETT_DNS_RR, offset, name, name_len,
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long_type_name, class_name, ttl, data_len);
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offset += (dptr - data_start);
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proto_tree_add_item(rr_tree, offset, data_len, "Primary name: %s", cname);
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proto_tree_add_item(rr_tree, offset, cname_len, "Primary name: %s", cname);
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}
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break;
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case T_PTR: /* "PTR" record */
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case T_SOA:
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{
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char mname[MAXDNAME];
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int mname_len;
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char rname[MAXDNAME];
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int rname_len;
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guint32 serial;
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guint32 refresh;
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guint32 retry;
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guint32 expire;
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guint32 minimum;
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rrptr = dptr;
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mname_len = get_dns_name(dns_data_ptr, rrptr, mname, sizeof(mname));
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rrptr += mname_len;
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trr = proto_tree_add_item(dns_tree, offset, (dptr - data_start) + data_len,
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"%s: type %s, class %s, mname %s",
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name, type_name, class_name, mname);
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rr_tree = add_rr_to_tree(trr, ETT_DNS_RR, offset, name, name_len,
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long_type_name, class_name, ttl, data_len);
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offset += (dptr - data_start);
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proto_tree_add_item(rr_tree, offset, mname_len, "Primary name server: %s",
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mname);
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offset += mname_len;
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rname_len = get_dns_name(dns_data_ptr, rrptr, rname, sizeof(rname));
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proto_tree_add_item(rr_tree, offset, rname_len, "Responsible authority's mailbox: %s",
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rname);
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rrptr += rname_len;
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offset += rname_len;
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serial = pntohl(rrptr);
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proto_tree_add_item(rr_tree, offset, 4, "Serial number: %u",
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serial);
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rrptr += 4;
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offset += 4;
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refresh = pntohl(rrptr);
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proto_tree_add_item(rr_tree, offset, 4, "Refresh interval: %s",
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time_secs_to_str(refresh));
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rrptr += 4;
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offset += 4;
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retry = pntohl(rrptr);
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proto_tree_add_item(rr_tree, offset, 4, "Retry interval: %s",
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time_secs_to_str(retry));
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rrptr += 4;
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offset += 4;
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expire = pntohl(rrptr);
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proto_tree_add_item(rr_tree, offset, 4, "Expiration limit: %s",
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time_secs_to_str(expire));
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rrptr += 4;
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offset += 4;
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minimum = pntohl(rrptr);
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proto_tree_add_item(rr_tree, offset, 4, "Minimum TTL: %s",
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time_secs_to_str(minimum));
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}
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break;
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case T_PTR:
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{
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char pname[MAXDNAME];
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int pname_len;
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pname_len = get_dns_name(dns_data_ptr, dptr, 0, pname, sizeof(pname));
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pname_len = get_dns_name(dns_data_ptr, dptr, pname, sizeof(pname));
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trr = proto_tree_add_item(dns_tree, offset, (dptr - data_start) + data_len,
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"%s: type %s, class %s, ptr %s",
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name, type_name, class_name, pname);
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rr_tree = add_rr_to_tree(trr, ETT_DNS_RR, offset, name, name_len,
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long_type_name, class_name, ttl, data_len);
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offset += (dptr - data_start);
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proto_tree_add_item(rr_tree, offset, data_len, "Domain name: %s", pname);
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proto_tree_add_item(rr_tree, offset, pname_len, "Domain name: %s", pname);
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break;
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}
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break;
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@ -2,7 +2,7 @@
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* Definitions for packet disassembly structures and routines used both by
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* DNS and NBNS.
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*
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* $Id: packet-dns.h,v 1.2 1999/03/23 03:14:36 gram Exp $
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* $Id: packet-dns.h,v 1.3 1999/05/27 05:35:08 guy Exp $
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*
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* Ethereal - Network traffic analyzer
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* By Gerald Combs <gerald@zing.org>
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@ -30,8 +30,8 @@
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char *dns_class_name(int class);
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int get_dns_name(const u_char *dns_data_ptr, const u_char *pd, int offset,
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char *nameptr, int maxname);
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int get_dns_name(const u_char *dns_data_ptr, const u_char *pd,
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char *name, int maxname);
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#define MAXDNAME 1025 /* maximum domain name length */
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@ -4,7 +4,7 @@
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* Gilbert Ramirez <gram@verdict.uthscsa.edu>
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* Much stuff added by Guy Harris <guy@netapp.com>
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*
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* $Id: packet-nbns.c,v 1.19 1999/05/10 22:07:09 guy Exp $
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* $Id: packet-nbns.c,v 1.20 1999/05/27 05:35:08 guy Exp $
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*
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* Ethereal - Network traffic analyzer
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* By Gerald Combs <gerald@zing.org>
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@ -185,7 +185,7 @@ get_nbns_name(const u_char *nbns_data_ptr, const u_char *pd,
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char nbname[MAXDNAME+4]; /* 4 for [<last char>] */
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char *pname, *pnbname, cname, cnbname;
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name_len = get_dns_name(nbns_data_ptr, pd, offset, name, sizeof(name));
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name_len = get_dns_name(nbns_data_ptr, pd + offset, name, sizeof(name));
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/* OK, now undo the first-level encoding. */
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pname = &name[0];
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