From 8be18a15ec980776c4dac294133282341d15bf77 Mon Sep 17 00:00:00 2001
From: Marcus Comstedt <marcus@mc.pp.se>
Date: Wed, 12 Apr 2000 00:34:57 +0200
Subject: [PATCH] Server side of protocol implemented.
Rev: lib/modules/Protocols.pmod/DNS.pmod:1.40
---
lib/modules/Protocols.pmod/DNS.pmod | 203 +++++++++++++++++++++++++---
1 file changed, 186 insertions(+), 17 deletions(-)
diff --git a/lib/modules/Protocols.pmod/DNS.pmod b/lib/modules/Protocols.pmod/DNS.pmod
index b83a2b57fe..36d7e70e31 100644
--- a/lib/modules/Protocols.pmod/DNS.pmod
+++ b/lib/modules/Protocols.pmod/DNS.pmod
@@ -1,4 +1,5 @@
// Not yet finished -- Fredrik Hubinette
+// RFC 1035
//! module Protocols
//! submodule DNS
@@ -22,6 +23,9 @@ constant T_MF=4;
constant T_CNAME=5;
constant T_SOA=6;
constant T_MB=7;
+constant T_MG=8;
+constant T_MR=9;
+constant T_NULL=10;
constant T_PTR=12;
constant T_HINFO=13;
constant T_MINFO=14;
@@ -39,31 +43,126 @@ class protocol
return sprintf("%c%s",strlen(s),s);
}
+ static private string mkname(string|array(string) labels, int pos,
+ mapping(string:int) comp)
+ {
+ if(stringp(labels))
+ labels = labels/"."-({""});
+ if(!labels || !sizeof(labels))
+ return "\0";
+ string n = labels*".";
+ if(comp[n])
+ return sprintf("%2c", comp[n]|0xc000);
+ else {
+ if(pos<0x4000)
+ comp[n]=pos;
+ string l = mklabel(labels[0]);
+ return l + mkname(labels[1..], pos+strlen(l), comp);
+ }
+ }
+
+ static private string mkrdata(mapping entry, int pos, mapping(string:int) c)
+ {
+ switch(entry->type) {
+ case T_CNAME:
+ return mkname(entry->cname, pos, c);
+ case T_PTR:
+ return mkname(entry->ptr, pos, c);
+ case T_NS:
+ return mkname(entry->ns, pos, c);
+ case T_MD:
+ return mkname(entry->md, pos, c);
+ case T_MF:
+ return mkname(entry->mf, pos, c);
+ case T_MB:
+ return mkname(entry->mb, pos, c);
+ case T_MG:
+ return mkname(entry->mg, pos, c);
+ case T_MR:
+ return mkname(entry->mr, pos, c);
+ case T_MX:
+ return sprintf("%2c", entry->preference)+mkname(entry->mx, pos+2, c);
+ case T_HINFO:
+ return sprintf("%1c%s%1c%s", strlen(entry->cpu||""), entry->cpu||"",
+ strlen(entry->os||""), entry->os||"");
+ case T_MINFO:
+ string rmailbx = mkname(entry->rmailbx, pos, c);
+ return rmailbx + mkname(entry->emailbx, pos+strlen(rmailbx), c);
+ case T_A:
+ case T_AAAA:
+ return sprintf("%@1c", (array(int))((entry->a||"0.0.0.0")/".")[0..3]);
+ case T_SOA:
+ string mname = mkname(entry->mname, pos, c);
+ return mname + mkname(entry->rname, pos+strlen(mname), c) +
+ sprintf("%4c%4c%4c%4c%4c", entry->serial, entry->refresh,
+ entry->retry, entry->expire, entry->minimum);
+ case T_TXT:
+ return Array.map(stringp(entry->txt)? ({entry->txt}):(entry->txt||({})),
+ lambda(string t) {
+ return sprintf("%1c%s", strlen(t), t);
+ })*"";
+ default:
+ return "";
+ }
+ }
+
+ static private string encode_entries(array(mapping) entries, int pos,
+ mapping(string:int) comp)
+ {
+ string res="";
+ foreach(entries, mapping entry) {
+ string e = mkname(entry->name, pos, comp)+
+ sprintf("%2c%2c%4c", entry->type, entry->cl, entry->ttl);
+ pos += strlen(e)+2;
+ string rd = entry->rdata || mkrdata(entry, pos, comp);
+ res += e + sprintf("%2c", strlen(rd)) + rd;
+ pos += strlen(rd);
+ }
+ return res;
+ }
+
+ string low_low_mkquery(mapping q)
+ {
+ array qd = q->qd && (arrayp(q->qd)? q->qd : ({q->qd}));
+ array an = q->an && (arrayp(q->an)? q->an : ({q->an}));
+ array ns = q->ns && (arrayp(q->ns)? q->ns : ({q->ns}));
+ array ar = q->ar && (arrayp(q->ar)? q->ar : ({q->ar}));
+ string r = sprintf("%2c%c%c%2c%2c%2c%2c", q->id,
+ ((q->rd)&1)|(((q->tc)&1)<<1)|(((q->aa)&1)<<2)|
+ (((q->opcode)&15)<<3)|(((q->qr)&1)<<7),
+ ((q->rcode)&15)|(((q->cd)&1)<<4)|(((q->ad)&1)<<5)|
+ (((q->ra)&1)<<7),
+ qd && sizeof(qd), an && sizeof(an),
+ ns && sizeof(ns), ar && sizeof(ar));
+ mapping(string:int) c = ([]);
+ if(qd)
+ foreach(qd, mapping _qd)
+ r += mkname(_qd->name, strlen(r), c) +
+ sprintf("%2c%2c", _qd->type, _qd->cl);
+ if(an)
+ r+=encode_entries(an, strlen(r), c);
+ if(ns)
+ r+=encode_entries(ns, strlen(r), c);
+ if(ar)
+ r+=encode_entries(ar, strlen(r), c);
+ return r;
+ }
+
string low_mkquery(int id,
string dname,
int cl,
int type)
{
- if ( dname[-1] == '.') dname = dname[..sizeof(dname)-2];
- return sprintf("%2c%c%c%2c%2c%2c%2c%s\000%2c%2c",
- id,
- 1,0,
- 1,
- 0,
- 0,
- 0,
- Array.map(dname/".",mklabel)*"",
- type,cl);
-
+ return low_low_mkquery((["id":id, "rd":1,
+ "qd":(["name":dname, "cl":cl, "type":type])]));
}
- // This will have to be generalized for
- // the server part...
- string mkquery(string dname,
- int cl,
- int type)
+ string mkquery(string|mapping dnameorquery, int|void cl, int|void type)
{
- return low_mkquery(random(65536),dname,cl,type);
+ if(mappingp(dnameorquery))
+ return low_low_mkquery(dnameorquery);
+ else
+ return low_mkquery(random(65536),dnameorquery,cl,type);
}
string decode_domain(string msg, array(int) n)
@@ -213,6 +312,76 @@ class protocol
}
};
+class server
+{
+ inherit protocol;
+ inherit Stdio.UDP : udp;
+
+ static void send_reply(mapping r, mapping q, mapping m)
+ {
+ // FIXME: Needs to handle truncation somehow.
+ if(!r)
+ r = (["rcode":4]);
+ r->id = q->id;
+ r->qr = 1;
+ r->opcode = q->opcode;
+ r->rd = q->rd;
+ r->qd = r->qd || q->qd;
+ string s = mkquery(r);
+ udp::send(m->ip, m->port, s);
+ }
+
+ static mapping reply_query(mapping q, mapping m)
+ {
+ // Override this function.
+ //
+ // Return mapping may contain:
+ // aa, ra, {ad, cd,} rcode, an, ns, ar
+
+ return 0;
+ }
+
+ static void handle_query(mapping q, mapping m)
+ {
+ mapping r = reply_query(q, m);
+ send_reply(r, q, m);
+ }
+
+ static void handle_response(mapping r, mapping m)
+ {
+ // This is a stub intended to simplify servers which allow recursion
+ }
+
+ static private void rec_data(mapping m)
+ {
+ mixed err;
+ mapping q;
+ if (err = catch {
+ q=decode_res(m->data);
+ }) {
+ werror(sprintf("DNS: Failed to read UDP packet.\n"
+ "%s\n", describe_backtrace(err)));
+ if(m && m->data && sizeof(m->data)>=2)
+ send_reply((["rcode":1]),
+ mkmapping(({"id"}), array_sscanf(m->data, "%2c")), m);
+ }
+ else if(q->qr)
+ handle_response(q, m);
+ else
+ handle_query(q, m);
+ }
+
+ void create(int|void port)
+ {
+ if(!port)
+ port = 53;
+ if(!udp::bind(port))
+ throw(({"DNS: failed to bind port "+port+".\n",backtrace()}));
+ udp::set_read_callback(rec_data);
+ }
+
+}
+
#define RETRIES 12
#define RETRY_DELAY 5
--
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