ref: c2e3b4dbbdc20cd7f49c2280dae0fa260f6c6e0a
parent: bc973654503031fa97b05e90e90db58269f53929
author: Michael Misch <michaelmisch1985@gmail.com>
date: Sat Jun 3 16:51:08 PDT 2023
More moving things
--- a/dnudpserver.c
+++ /dev/null
@@ -1,336 +1,0 @@
-#include <u.h>
-#include <libc.h>
-#include <ip.h>
-#include "dns.h"
-
-enum {- Logqueries = 0,
-};
-
-static int udpannounce(char*);
-static void reply(int, uchar*, DNSmsg*, Request*);
-
-typedef struct Inprogress Inprogress;
-struct Inprogress
-{- int inuse;
- Udphdr uh;
- DN *owner;
- ushort type;
- int id;
-};
-Inprogress inprog[Maxactive+2];
-
-typedef struct Forwtarg Forwtarg;
-struct Forwtarg {- char *host;
- uchar addr[IPaddrlen];
- int fd;
- ulong lastdial;
-};
-Forwtarg forwtarg[10];
-int forwtcount;
-
-static char *hmsg = "headers";
-
-/*
- * record client id and ignore retransmissions.
- * we're still single thread at this point.
- */
-static Inprogress*
-clientrxmit(DNSmsg *req, uchar *buf)
-{- Inprogress *p, *empty;
- Udphdr *uh;
-
- uh = (Udphdr *)buf;
- empty = nil;
- for(p = inprog; p < &inprog[Maxactive]; p++){- if(p->inuse == 0){- if(empty == nil)
- empty = p;
- continue;
- }
- if(req->id == p->id)
- if(req->qd->owner == p->owner)
- if(req->qd->type == p->type)
- if(memcmp(uh, &p->uh, Udphdrsize) == 0)
- return nil;
- }
- if(empty == nil)
- return nil; /* shouldn't happen: see slave() & Maxactive def'n */
-
- empty->id = req->id;
- empty->owner = req->qd->owner;
- empty->type = req->qd->type;
- if (empty->type != req->qd->type)
- dnslog("clientrxmit: bogus req->qd->type %d", req->qd->type);- memmove(&empty->uh, uh, Udphdrsize);
- empty->inuse = 1;
- return empty;
-}
-
-int
-addforwtarg(char *host)
-{- Forwtarg *tp;
-
- if (forwtcount >= nelem(forwtarg)) {- dnslog("too many forwarding targets");- return -1;
- }
- tp = forwtarg + forwtcount;
- if(parseip(tp->addr, host) == -1) {- dnslog("can't parse ip %s", host);- return -1;
- }
- tp->lastdial = time(nil);
- tp->fd = udpport(mntpt);
- if (tp->fd < 0)
- return -1;
-
- free(tp->host);
- tp->host = estrdup(host);
- forwtcount++;
- return 0;
-}
-
-/*
- * fast forwarding of incoming queries to other dns servers.
- * intended primarily for debugging.
- */
-static void
-redistrib(uchar *buf, int len)
-{- uchar save[Udphdrsize];
- Forwtarg *tp;
- Udphdr *uh;
-
- memmove(save, buf, Udphdrsize);
-
- uh = (Udphdr *)buf;
- for (tp = forwtarg; tp < forwtarg + forwtcount; tp++)
- if (tp->fd >= 0) {- memmove(uh->raddr, tp->addr, sizeof tp->addr);
- hnputs(uh->rport, 53); /* dns port */
- if (write(tp->fd, buf, len) != len) {- close(tp->fd);
- tp->fd = -1;
- }
- } else if (tp->host && time(nil) - tp->lastdial > 60) {- tp->lastdial = time(nil);
- tp->fd = udpport(mntpt);
- }
-
- memmove(buf, save, Udphdrsize);
-}
-
-/*
- * a process to act as a dns server for outside requests
- */
-void
-dnudpserver(char *mntpt)
-{- volatile int fd, len, op, rcode;
- char *volatile err;
- volatile char tname[32];
- volatile uchar buf[Udphdrsize + Maxudp + 1024];
- volatile DNSmsg reqmsg, repmsg;
- Inprogress *volatile p;
- volatile Request req;
- Udphdr *volatile uh;
-
- /*
- * fork sharing text, data, and bss with parent.
- * stay in the same note group.
- */
- switch(rfork(RFPROC|RFMEM|RFNOWAIT)){- case -1:
- break;
- case 0:
- break;
- default:
- return;
- }
-
- fd = -1;
-restart:
- procsetname("udp server announcing");- if(fd >= 0)
- close(fd);
- while((fd = udpannounce(mntpt)) < 0)
- sleep(5000);
-
-// procsetname("udp server");- memset(&req, 0, sizeof req);
- if(setjmp(req.mret))
- putactivity(0);
- req.isslave = 0;
- req.id = 0;
- req.aborttime = 0;
-
- /* loop on requests */
- for(;; putactivity(0)){- procsetname("served %lud udp; %lud alarms",- stats.qrecvdudp, stats.alarms);
- memset(&repmsg, 0, sizeof repmsg);
- memset(&reqmsg, 0, sizeof reqmsg);
-
- alarm(60*1000);
- len = read(fd, buf, sizeof buf);
- alarm(0);
- if(len <= Udphdrsize)
- goto restart;
-
- if(forwtcount > 0)
- redistrib(buf, len);
-
- uh = (Udphdr*)buf;
- len -= Udphdrsize;
-
- // dnslog("read received UDP from %I to %I",- // ((Udphdr*)buf)->raddr, ((Udphdr*)buf)->laddr);
- getactivity(&req, 0);
- req.aborttime = timems() + Maxreqtm;
- req.from = smprint("%I", buf);- rcode = 0;
- stats.qrecvdudp++;
-
- err = convM2DNS(&buf[Udphdrsize], len, &reqmsg, &rcode);
- if(err){- /* first bytes in buf are source IP addr */
- dnslog("server: input error: %s from %I", err, buf);- free(err);
- goto freereq;
- }
- if (rcode == 0)
- if(reqmsg.qdcount < 1){- dnslog("server: no questions from %I", buf);- goto freereq;
- } else if(reqmsg.flags & Fresp){- dnslog("server: reply not request from %I", buf);- goto freereq;
- }
- op = reqmsg.flags & Omask;
- if(op != Oquery && op != Onotify){- dnslog("server: op %d from %I", reqmsg.flags & Omask,- buf);
- goto freereq;
- }
-
- if(reqmsg.qd == nil){- dnslog("server: no question RR from %I", buf);- goto freereq;
- }
-
- if(debug || (trace && subsume(trace, reqmsg.qd->owner->name)))
- dnslog("%d: serve (%I/%d) %d %s %s",- req.id, buf, uh->rport[0]<<8 | uh->rport[1],
- reqmsg.id, reqmsg.qd->owner->name,
- rrname(reqmsg.qd->type, tname, sizeof tname));
-
- p = clientrxmit(&reqmsg, buf);
- if(p == nil){- if(debug)
- dnslog("%d: duplicate", req.id);- goto freereq;
- }
-
- if (Logqueries) {- RR *rr;
-
- for (rr = reqmsg.qd; rr; rr = rr->next)
- syslog(0, "dnsq", "id %d: (%I/%d) %d %s %s",
- req.id, buf, uh->rport[0]<<8 |
- uh->rport[1], reqmsg.id,
- reqmsg.qd->owner->name,
- rrname(reqmsg.qd->type, tname,
- sizeof tname));
- }
- /* loop through each question */
- while(reqmsg.qd){- memset(&repmsg, 0, sizeof repmsg);
- switch(op){- case Oquery:
- dnserver(&reqmsg, &repmsg, &req, buf, rcode);
- break;
- case Onotify:
- dnnotify(&reqmsg, &repmsg, &req);
- break;
- }
- /* send reply on fd to address in buf's udp hdr */
- reply(fd, buf, &repmsg, &req);
- freeanswers(&repmsg);
- }
-
- p->inuse = 0;
-freereq:
- free(req.from);
- req.from = nil;
- freeanswers(&reqmsg);
- if(req.isslave){- putactivity(0);
- _exits(0);
- }
- }
-}
-
-/*
- * announce on well-known dns udp port and set message style interface
- */
-static int
-udpannounce(char *mntpt)
-{- int data, ctl;
- char dir[64], datafile[64+6];
- static int whined;
-
- /* get a udp port */
- sprint(datafile, "%s/udp!*!dns", mntpt);
- ctl = announce(datafile, dir);
- if(ctl < 0){- if(!whined++)
- warning("can't announce on %s", datafile);- return -1;
- }
-
- /* turn on header style interface */
- if(write(ctl, hmsg, strlen(hmsg)) != strlen(hmsg)){- close(ctl);
- if(!whined++)
- warning("can't enable headers on %s", datafile);- return -1;
- }
-
- snprint(datafile, sizeof(datafile), "%s/data", dir);
- data = open(datafile, ORDWR);
- if(data < 0){- close(ctl);
- if(!whined++)
- warning("can't open %s to announce on dns udp port",- datafile);
- return -1;
- }
-
- close(ctl);
- return data;
-}
-
-static void
-reply(int fd, uchar *buf, DNSmsg *rep, Request *reqp)
-{- int len;
- char tname[32];
-
- if(debug || (trace && subsume(trace, rep->qd->owner->name)))
- dnslog("%d: reply (%I/%d) %d %s %s qd %R an %R ns %R ar %R",- reqp->id, buf, buf[4]<<8 | buf[5],
- rep->id, rep->qd->owner->name,
- rrname(rep->qd->type, tname, sizeof tname),
- rep->qd, rep->an, rep->ns, rep->ar);
-
- len = convDNS2M(rep, &buf[Udphdrsize], Maxudp);
- len += Udphdrsize;
- if(write(fd, buf, len) != len)
- dnslog("error sending reply: %r");-}