source: npl/internetserver/djbdns/CVE2008-4392_0001-dnscache-merge-similar-outgoing-queries.patch @ 105afb5

diff --git a/Makefile b/Makefile
index 1429643..bc047c0 100644
--- a/Makefile
+++ b/Makefile
@@ -318,11 +318,11 @@ stralloc.h iopause.h taia.h tai.h uint64.h taia.h
        ./compile dns_txt.c
 
 dnscache: \
-load dnscache.o droproot.o okclient.o log.o cache.o query.o \
+load dnscache.o droproot.o okclient.o log.o cache.o query.o qmerge.o \
 response.o dd.o roots.o iopause.o prot.o dns.a env.a alloc.a buffer.a \
 libtai.a unix.a byte.a socket.lib
        ./load dnscache droproot.o okclient.o log.o cache.o \
-       query.o response.o dd.o roots.o iopause.o prot.o dns.a \
+       query.o qmerge.o response.o dd.o roots.o iopause.o prot.o dns.a \
        env.a alloc.a buffer.a libtai.a unix.a byte.a  `cat \
        socket.lib`
 
@@ -343,7 +343,7 @@ compile dnscache.c env.h exit.h scan.h strerr.h error.h ip4.h \
 uint16.h uint64.h socket.h uint16.h dns.h stralloc.h gen_alloc.h \
 iopause.h taia.h tai.h uint64.h taia.h taia.h byte.h roots.h fmt.h \
 iopause.h query.h dns.h uint32.h alloc.h response.h uint32.h cache.h \
-uint32.h uint64.h ndelay.h log.h uint64.h okclient.h droproot.h
+uint32.h uint64.h ndelay.h log.h uint64.h okclient.h droproot.h maxclient.h
        ./compile dnscache.c
 
 dnsfilter: \
@@ -687,11 +687,16 @@ qlog.o: \
 compile qlog.c buffer.h qlog.h uint16.h
        ./compile qlog.c
 
+qmerge.o: \
+compile qmerge.c qmerge.h dns.h stralloc.h gen_alloc.h iopause.h \
+taia.h tai.h uint64.h log.h maxclient.h
+       ./compile qmerge.c
+
 query.o: \
 compile query.c error.h roots.h log.h uint64.h case.h cache.h \
 uint32.h uint64.h byte.h dns.h stralloc.h gen_alloc.h iopause.h \
 taia.h tai.h uint64.h taia.h uint64.h uint32.h uint16.h dd.h alloc.h \
-response.h uint32.h query.h dns.h uint32.h
+response.h uint32.h query.h dns.h uint32.h qmerge.h
        ./compile query.c
 
 random-ip: \
diff --git a/dnscache.c b/dnscache.c
index 8c899a3..5ccb16a 100644
--- a/dnscache.c
+++ b/dnscache.c
@@ -22,6 +22,7 @@
 #include "log.h"
 #include "okclient.h"
 #include "droproot.h"
+#include "maxclient.h"
 
 static int packetquery(char *buf,unsigned int len,char **q,char qtype[2],char qclass[2],char id[2])
 {
@@ -54,7 +55,6 @@ uint64 numqueries = 0;
 
 static int udp53;
 
-#define MAXUDP 200
 static struct udpclient {
   struct query q;
   struct taia start;
@@ -131,7 +131,6 @@ void u_new(void)
 
 static int tcp53;
 
-#define MAXTCP 20
 struct tcpclient {
   struct query q;
   struct taia start;
diff --git a/log.c b/log.c
index c43e8b0..b8cd7ce 100644
--- a/log.c
+++ b/log.c
@@ -150,6 +150,13 @@ void log_tx(const char *q,const char qtype[2],const char *control,const char ser
   line();
 }
 
+void log_tx_piggyback(const char *q, const char qtype[2], const char *control)
+{
+  string("txpb ");
+  logtype(qtype); space(); name(q); space(); name(control);
+  line();
+}
+
 void log_cachedanswer(const char *q,const char type[2])
 {
   string("cached "); logtype(type); space();
diff --git a/log.h b/log.h
index fe62fa3..d9a829b 100644
--- a/log.h
+++ b/log.h
@@ -18,6 +18,7 @@ extern void log_cachednxdomain(const char *);
 extern void log_cachedns(const char *,const char *);
 
 extern void log_tx(const char *,const char *,const char *,const char *,unsigned int);
+extern void log_tx_piggyback(const char *,const char *,const char *);
 
 extern void log_nxdomain(const char *,const char *,unsigned int);
 extern void log_nodata(const char *,const char *,const char *,unsigned int);
diff --git a/maxclient.h b/maxclient.h
new file mode 100644
index 0000000..e52fcd1
--- /dev/null
+++ b/maxclient.h
@@ -0,0 +1,7 @@
+#ifndef MAXCLIENT_H
+#define MAXCLIENT_H
+
+#define MAXUDP 200
+#define MAXTCP 20
+
+#endif /* MAXCLIENT_H */
diff --git a/qmerge.c b/qmerge.c
new file mode 100644
index 0000000..7c92299
--- /dev/null
+++ b/qmerge.c
@@ -0,0 +1,115 @@
+#include "qmerge.h"
+#include "byte.h"
+#include "log.h"
+#include "maxclient.h"
+
+#define QMERGE_MAX (MAXUDP+MAXTCP)
+struct qmerge inprogress[QMERGE_MAX];
+
+static
+int qmerge_key_init(struct qmerge_key *qmk, const char *q, const char qtype[2],
+    const char *control)
+{
+  if (!dns_domain_copy(&qmk->q, q)) return 0;
+  byte_copy(qmk->qtype, 2, qtype);
+  if (!dns_domain_copy(&qmk->control, control)) return 0;
+  return 1;
+}
+
+static
+int qmerge_key_equal(struct qmerge_key *a, struct qmerge_key *b)
+{
+  return
+    byte_equal(a->qtype, 2, b->qtype) &&
+    dns_domain_equal(a->q, b->q) &&
+    dns_domain_equal(a->control, b->control);
+}
+
+static
+void qmerge_key_free(struct qmerge_key *qmk)
+{
+  dns_domain_free(&qmk->q);
+  dns_domain_free(&qmk->control);
+}
+
+void qmerge_free(struct qmerge **x)
+{
+  struct qmerge *qm;
+
+  qm = *x;
+  *x = 0;
+  if (!qm || !qm->active) return;
+
+  qm->active--;
+  if (!qm->active) {
+    qmerge_key_free(&qm->key);
+    dns_transmit_free(&qm->dt);
+  }
+}
+
+int qmerge_start(struct qmerge **qm, const char servers[64], int flagrecursive,
+    const char *q, const char qtype[2], const char localip[4],
+    const char *control)
+{
+  struct qmerge_key k;
+  int i;
+  int r;
+
+  qmerge_free(qm);
+
+  byte_zero(&k, sizeof k);
+  if (!qmerge_key_init(&k, q, qtype, control)) return -1;
+  for (i = 0; i < QMERGE_MAX; i++) {
+    if (!inprogress[i].active) continue;
+    if (!qmerge_key_equal(&k, &inprogress[i].key)) continue;
+    log_tx_piggyback(q, qtype, control);
+    inprogress[i].active++;
+    *qm = &inprogress[i];
+    qmerge_key_free(&k);
+    return 0;
+  }
+
+  for (i = 0; i < QMERGE_MAX; i++)
+    if (!inprogress[i].active)
+      break;
+  if (i == QMERGE_MAX) return -1;
+
+  log_tx(q, qtype, control, servers, 0);
+  r = dns_transmit_start(&inprogress[i].dt, servers, flagrecursive, q, qtype, localip);
+  if (r == -1) { qmerge_key_free(&k); return -1; }
+  inprogress[i].active++;
+  inprogress[i].state = 0;
+  qmerge_key_free(&inprogress[i].key);
+  byte_copy(&inprogress[i].key, sizeof k, &k);
+  *qm = &inprogress[i];
+  return 0;
+}
+
+void qmerge_io(struct qmerge *qm, iopause_fd *io, struct taia *deadline)
+{
+  if (qm->state == 0) {
+    dns_transmit_io(&qm->dt, io, deadline);
+    qm->state = 1;
+  }
+  else {
+    io->fd = -1;
+    io->events = 0;
+  }
+}
+
+int qmerge_get(struct qmerge **x, const iopause_fd *io, const struct taia *when)
+{
+  int r;
+  struct qmerge *qm;
+
+  qm = *x;
+  if (qm->state == -1) return -1; /* previous error */
+  if (qm->state == 0) return 0; /* no packet */
+  if (qm->state == 2) return 1; /* already got packet */
+
+  r = dns_transmit_get(&qm->dt, io, when);
+  if (r == -1) { qm->state = -1; return -1; } /* error */
+  if (r == 0) { qm->state = 0; return 0; } /* must wait for i/o */
+  if (r == 1) { qm->state = 2; return 1; } /* got packet */
+  return -1; /* bug */
+}
diff --git a/qmerge.h b/qmerge.h
new file mode 100644
index 0000000..9a58157
--- /dev/null
+++ b/qmerge.h
@@ -0,0 +1,24 @@
+#ifndef QMERGE_H
+#define QMERGE_H
+
+#include "dns.h"
+
+struct qmerge_key {
+  char *q;
+  char qtype[2];
+  char *control;
+};
+
+struct qmerge {
+  int active;
+  struct qmerge_key key;
+  struct dns_transmit dt;
+  int state; /* -1 = error, 0 = need io, 1 = need get, 2 = got packet */
+};
+
+extern int qmerge_start(struct qmerge **,const char *,int,const char *,const char *,const char *,const char *);
+extern void qmerge_io(struct qmerge *,iopause_fd *,struct taia *);
+extern int qmerge_get(struct qmerge **,const iopause_fd *,const struct taia *);
+extern void qmerge_free(struct qmerge **);
+
+#endif /* QMERGE_H */
diff --git a/query.c b/query.c
index 46cdc00..f091fdd 100644
--- a/query.c
+++ b/query.c
@@ -81,7 +81,7 @@ static void cleanup(struct query *z)
   int j;
   int k;
 
-  dns_transmit_free(&z->dt);
+  qmerge_free(&z->qm);
   for (j = 0;j < QUERY_MAXALIAS;++j)
     dns_domain_free(&z->alias[j]);
   for (j = 0;j < QUERY_MAXLEVEL;++j) {
@@ -429,14 +429,8 @@ static int doit(struct query *z,int state)
   if (j == 64) goto SERVFAIL;
 
   dns_sortip(z->servers[z->level],64);
-  if (z->level) {
-    log_tx(z->name[z->level],DNS_T_A,z->control[z->level],z->servers[z->level],z->level);
-    if (dns_transmit_start(&z->dt,z->servers[z->level],flagforwardonly,z->name[z->level],DNS_T_A,z->localip) == -1) goto DIE;
-  }
-  else {
-    log_tx(z->name[0],z->type,z->control[0],z->servers[0],0);
-    if (dns_transmit_start(&z->dt,z->servers[0],flagforwardonly,z->name[0],z->type,z->localip) == -1) goto DIE;
-  }
+  dtype = z->level ? DNS_T_A : z->type;
+  if (qmerge_start(&z->qm,z->servers[z->level],flagforwardonly,z->name[z->level],dtype,z->localip,z->control[z->level]) == -1) goto DIE;
   return 0;
 
 
@@ -450,10 +444,10 @@ static int doit(struct query *z,int state)
 
   HAVEPACKET:
   if (++z->loop == 100) goto DIE;
-  buf = z->dt.packet;
-  len = z->dt.packetlen;
+  buf = z->qm->dt.packet;
+  len = z->qm->dt.packetlen;
 
-  whichserver = z->dt.servers + 4 * z->dt.curserver;
+  whichserver = z->qm->dt.servers + 4 * z->qm->dt.curserver;
   control = z->control[z->level];
   d = z->name[z->level];
   dtype = z->level ? DNS_T_A : z->type;
@@ -836,7 +830,7 @@ int query_start(struct query *z,char *dn,char type[2],char class[2],char localip
 
 int query_get(struct query *z,iopause_fd *x,struct taia *stamp)
 {
-  switch(dns_transmit_get(&z->dt,x,stamp)) {
+  switch(qmerge_get(&z->qm,x,stamp)) {
     case 1:
       return doit(z,1);
     case -1:
@@ -847,5 +841,5 @@ int query_get(struct query *z,iopause_fd *x,struct taia *stamp)
 
 void query_io(struct query *z,iopause_fd *x,struct taia *deadline)
 {
-  dns_transmit_io(&z->dt,x,deadline);
+  qmerge_io(z->qm,x,deadline);
 }
diff --git a/query.h b/query.h
index eff68b2..06feab4 100644
--- a/query.h
+++ b/query.h
@@ -1,7 +1,7 @@
 #ifndef QUERY_H
 #define QUERY_H
 
-#include "dns.h"
+#include "qmerge.h"
 #include "uint32.h"
 
 #define QUERY_MAXLEVEL 5
@@ -20,7 +20,7 @@ struct query {
   char localip[4];
   char type[2];
   char class[2];
-  struct dns_transmit dt;
+  struct qmerge *qm;
 } ;
 
 extern int query_start(struct query *,char *,char *,char *,char *);