ndb/dns: handle txt rr strings as binary, remove nullrr ndb code

txt and caa rr strings might contain binary control characters
such as newlines and double quotes which mess up the output
in ndb(6) format.
so handle them as binary blobs internally and escape special
characters as \DDD where D is a octal digit when printing.

txtrr() will unescape them when reading into internal
binary representation.

remove the undocumented nullrr ndb attribute parsing code.
This commit is contained in:
cinap_lenrek 2021-11-03 20:09:02 +00:00
parent 2899b719ae
commit 5de1f3d9cf
5 changed files with 106 additions and 127 deletions

View file

@ -26,7 +26,7 @@ struct Dict
#define NAME(x) p = pname(p, ep, x, dp)
#define LABEL(x) p = pname(p, ep, x, nil)
#define SYMBOL(x) p = psym(p, ep, x)
#define STRING(x) p = pstr(p, ep, x)
#define STRING(x, n) p = pstr(p, ep, x, n)
#define BYTES(x, n) p = pbytes(p, ep, x, n)
#define USHORT(x) p = pushort(p, ep, x)
#define UCHAR(x) p = puchar(p, ep, x)
@ -35,24 +35,21 @@ struct Dict
#define V6ADDR(x) p = pv6addr(p, ep, x)
static uchar*
psym(uchar *p, uchar *ep, char *np)
pstr(uchar *p, uchar *ep, uchar *s, int n)
{
int n;
n = strlen(np);
if(n >= Strlen) /* DNS maximum length string */
n = Strlen-1;
if(ep - p < n+1) /* see if it fits in the buffer */
return ep+1;
*p++ = n;
memmove(p, np, n);
memmove(p, s, n);
return p + n;
}
static uchar*
pstr(uchar *p, uchar *ep, char *np)
psym(uchar *p, uchar *ep, char *np)
{
return psym(p, ep, np);
return pstr(p, ep, (uchar*)np, strlen(np));
}
static uchar*
@ -266,7 +263,7 @@ convRR2M(RR *rp, uchar *p, uchar *ep, Dict *dp)
break;
case Ttxt:
for(t = rp->txt; t != nil; t = t->next)
STRING(t->p);
STRING(t->data, t->dlen);
break;
case Tnull:
BYTES(rp->null->data, rp->null->dlen);

View file

@ -103,7 +103,7 @@ gv4addr(RR *rp, Scan *sp)
char addr[32];
if(sp->err)
return 0;
return nil;
if(sp->ep - sp->p < 4)
return (DN*)errtoolong(rp, sp, sp->ep - sp->p, 4, "gv4addr");
snprint(addr, sizeof addr, "%V", sp->p);
@ -117,7 +117,7 @@ gv6addr(RR *rp, Scan *sp)
char addr[64];
if(sp->err)
return 0;
return nil;
if(sp->ep - sp->p < IPaddrlen)
return (DN*)errtoolong(rp, sp, sp->ep - sp->p, IPaddrlen,
"gv6addr");
@ -133,20 +133,20 @@ gv6addr(RR *rp, Scan *sp)
static DN*
gsym(RR *rp, Scan *sp)
{
char sym[Strlen];
int n;
char sym[Strlen+1];
if(sp->err)
return 0;
return nil;
n = 0;
if (sp->p < sp->ep)
n = *(sp->p++);
if(sp->ep - sp->p < n)
return (DN*)errtoolong(rp, sp, sp->ep - sp->p, n, "gsym");
if(n > Strlen){
if(n >= Strlen){
sp->err = "illegal string (symbol)";
return 0;
return nil;
}
strncpy(sym, (char*)sp->p, n);
sym[n] = 0;
@ -164,30 +164,28 @@ static Txt*
gstr(RR *rp, Scan *sp)
{
int n;
char sym[Strlen+1];
Txt *t;
if(sp->err)
return 0;
return nil;
n = 0;
if (sp->p < sp->ep)
n = *(sp->p++);
if(sp->ep - sp->p < n)
return (Txt*)errtoolong(rp, sp, sp->ep - sp->p, n, "gstr");
if(n > Strlen){
if(n >= Strlen){
sp->err = "illegal string";
return 0;
return nil;
}
strncpy(sym, (char*)sp->p, n);
sym[n] = 0;
if (strlen(sym) != n)
sp->err = "string shorter than declared length";
sp->p += n;
t = emalloc(sizeof(*t));
t->next = nil;
t->p = estrdup(sym);
t->dlen = n;
t->data = emalloc(n);
memmove(t->data, sp->p, n);
sp->p += n;
return t;
}

View file

@ -36,7 +36,6 @@ static RR* doaxfr(Ndb*, char*);
static Ndbtuple*look(Ndbtuple*, Ndbtuple*, char*);
static RR* mxrr(Ndbtuple*, Ndbtuple*);
static RR* nsrr(Ndbtuple*, Ndbtuple*);
static RR* nullrr(Ndbtuple*, Ndbtuple*);
static RR* ptrrr(Ndbtuple*, Ndbtuple*);
static RR* soarr(Ndbtuple*, Ndbtuple*);
static RR* srvrr(Ndbtuple*, Ndbtuple*);
@ -50,7 +49,6 @@ static int implemented[] =
[Tcname] 1,
[Tmx] 1,
[Tns] 1,
[Tnull] 1,
[Tptr] 1,
[Tsoa] 1,
[Tsrv] 1,
@ -228,10 +226,6 @@ dblookup1(char *name, int type, int auth, int ttl)
attr2 = "ipv6";
f = addr6rr;
break;
case Tnull:
attr = "nullrr";
f = nullrr;
break;
case Tns:
attr = "ns";
f = nsrr;
@ -246,7 +240,7 @@ dblookup1(char *name, int type, int auth, int ttl)
break;
case Ttxt:
attr = "txt";
attr2 = "txtrr"; /* undocumented */
attr2 = "txtrr"; /* obsolete */
f = txtrr;
break;
case Tmx:
@ -435,27 +429,17 @@ addrrr(Ndbtuple*, Ndbtuple *pair)
return rp;
}
static RR*
nullrr(Ndbtuple*, Ndbtuple *pair)
{
RR *rp;
rp = rralloc(Tnull);
rp->null->data = (uchar*)estrdup(pair->val);
rp->null->dlen = strlen((char*)rp->null->data);
return rp;
}
/*
* txt rr strings are at most 255 bytes long. one
* txt rr strings are at most Strlen-1 bytes long. one
* can represent longer strings by multiple concatenated
* <= 255 byte ones.
* < Strlen byte ones.
*/
static RR*
txtrr(Ndbtuple*, Ndbtuple *pair)
{
RR *rp;
Txt *t, **l;
int i, len, sofar;
int i, n, len, sofar;
rp = rralloc(Ttxt);
l = &rp->txt;
@ -466,14 +450,26 @@ txtrr(Ndbtuple*, Ndbtuple *pair)
t = emalloc(sizeof(*t));
t->next = nil;
i = len-sofar;
if(i > 255)
i = 255;
n = len-sofar;
if(n >= Strlen)
n = Strlen-1;
t->data = emalloc(n);
t->p = emalloc(i+1);
memmove(t->p, pair->val+sofar, i);
t->p[i] = 0;
sofar += i;
/* see bslashfmt() */
for(i = 0; i < n && sofar < len; i++){
uint c = pair->val[sofar++];
if(c == '\\' && sofar < len){
if(pair->val[sofar] >= '0' && pair->val[sofar] <= '7'){
c = pair->val[sofar++] - '0';
while(pair->val[sofar] >= '0' && pair->val[sofar] <= '7')
c = (c << 3) | (pair->val[sofar++] - '0');
} else {
c = pair->val[sofar++];
}
}
t->data[i] = c;
}
t->dlen = i;
*l = t;
l = &t->next;
@ -672,9 +668,7 @@ dbpair2cache(DN *dp, Ndbtuple *entry, Ndbtuple *pair)
rp = srvrr(entry, pair);
else if(strcmp(pair->attr, "cname") == 0)
rp = cnamerr(entry, pair);
else if(strcmp(pair->attr, "nullrr") == 0)
rp = nullrr(entry, pair);
else if(strcmp(pair->attr, "txtrr") == 0) /* undocumented */
else if(strcmp(pair->attr, "txtrr") == 0) /* obsolete */
rp = txtrr(entry, pair);
else if(strcmp(pair->attr, "txt") == 0)
rp = txtrr(entry, pair);

View file

@ -139,7 +139,6 @@ Lock dnlock;
static ulong agefreq = Defagefreq;
static int rrequiv(RR *r1, RR *r2);
static int sencodefmt(Fmt*);
static void
ding(void*, char *msg)
@ -157,9 +156,10 @@ dninit(void)
fmtinstall('E', eipfmt);
fmtinstall('I', eipfmt);
fmtinstall('V', eipfmt);
fmtinstall('\\', bslashfmt);
fmtinstall('R', rrfmt);
fmtinstall('Q', rravfmt);
fmtinstall('H', sencodefmt);
fmtinstall('H', encodefmt);
dnvars.oldest = maxage;
dnvars.names = 0;
@ -944,7 +944,9 @@ rrcopy(RR *rp, RR **last)
*l = nil;
for(t = rp->txt; t != nil; t = t->next){
nt = emalloc(sizeof(*nt));
nt->p = estrdup(t->p);
nt->dlen = t->dlen;
nt->data = emalloc(t->dlen);
memmove(nt->data, t->data, t->dlen);
nt->next = nil;
*l = nt;
l = &nt->next;
@ -1194,6 +1196,47 @@ idnname(DN *dn, char *buf, int nbuf)
return name;
}
/*
* txt rr strings can contain binary data such as
* control characters and double quotes (") which would
* collide with ndb(6) format.
* escape special characters by encoding them as: \DDD
* where D is a octal digit. backslash (\) is escaped
* by doubling. valid utf8 is encoded verbatim.
*/
int
bslashfmt(Fmt *f)
{
int len, out, n, c;
uchar *data;
out = 0;
len = f->prec;
f->prec = 0;
f->flags &= ~FmtPrec;
data = va_arg(f->args, uchar*);
for(; len > 0; data += n, len -= n){
if(*data >= Runeself && fullrune((char*)data, len)){
Rune r;
n = chartorune(&r, (char*)data);
if(r != Runeerror){
out += fmtprint(f, "%C", r);
continue;
}
}
c = *data;
if(c < ' ' || c == '"' || c > '~')
out += fmtprint(f, "\\%.3o", c);
else if(c == '\\')
out += fmtprint(f, "\\\\");
else
out += fmtprint(f, "%c", c);
n = 1;
}
return out;
}
/*
* print conversion for rr records
*/
@ -1280,7 +1323,7 @@ rrfmt(Fmt *f)
case Ttxt:
fmtprint(&fstr, "\t");
for(t = rp->txt; t != nil; t = t->next)
fmtprint(&fstr, "%s", t->p);
fmtprint(&fstr, "%.*\\", t->dlen, t->data);
break;
case Trp:
fmtprint(&fstr, "\t%s %s", dnname(rp->rmb), dnname(rp->rp));
@ -1314,9 +1357,9 @@ rrfmt(Fmt *f)
if (rp->caa == nil)
fmtprint(&fstr, "\t<null> <null> <null>");
else
fmtprint(&fstr, "\t%d %s %.*s",
fmtprint(&fstr, "\t%d %s %.*\\",
rp->caa->flags, dnname(rp->caa->tag),
rp->caa->dlen, (char*)rp->caa->data);
rp->caa->dlen, rp->caa->data);
break;
}
out:
@ -1416,7 +1459,7 @@ rravfmt(Fmt *f)
case Ttxt:
fmtprint(&fstr, " txt=\"");
for(t = rp->txt; t != nil; t = t->next)
fmtprint(&fstr, "%s", t->p);
fmtprint(&fstr, "%.*\\", t->dlen, t->data);
fmtprint(&fstr, "\"");
break;
case Trp:
@ -1453,9 +1496,9 @@ rravfmt(Fmt *f)
if (rp->caa == nil)
fmtprint(&fstr, " flags=<null> tag=<null> caa=<null>");
else
fmtprint(&fstr, " flags=%d tag=%s caa=\"%.*s\"",
fmtprint(&fstr, " flags=%d tag=%s caa=\"%.*\\\"",
rp->caa->flags, dnname(rp->caa->tag),
rp->caa->dlen, (char*)rp->caa->data);
rp->caa->dlen, rp->caa->data);
break;
}
out:
@ -1574,14 +1617,14 @@ certequiv(Cert *a, Cert *b)
static int
txtequiv(Txt *a, Txt *b)
{
char *ap, *ae, *bp, *be;
uchar *ap, *ae, *bp, *be;
int n;
for(ap = ae = bp = be = nil;;ap += n, bp += n){
while(a != nil && (ap == nil || (ap == ae && (a = a->next) != nil)))
ap = a->p, ae = ap + strlen(ap);
while(b != nil && (bp == nil || (bp == be && (b = b->next) != nil)))
bp = b->p, be = bp + strlen(bp);
while(a != nil && (ap == nil || (ap >= ae && (a = a->next) != nil)))
ap = a->data, ae = ap + a->dlen;
while(b != nil && (bp == nil || (bp >= be && (b = b->next) != nil)))
bp = b->data, be = bp + b->dlen;
if(a == b || a == nil || b == nil)
break;
n = ae - ap;
@ -1709,61 +1752,6 @@ randomize(RR *rp)
return first;
}
static int
sencodefmt(Fmt *f)
{
int i, len, ilen, rv;
char *out, *buf;
uchar *b;
char obuf[64]; /* rsc optimization */
if(!(f->flags&FmtPrec) || f->prec < 1)
goto error;
b = va_arg(f->args, uchar*);
if(b == nil)
goto error;
/* if it's a printable, go for it */
len = f->prec;
for(i = 0; i < len; i++)
if(!isprint(b[i]))
break;
if(i == len){
if(len >= sizeof obuf)
len = sizeof(obuf)-1;
memmove(obuf, b, len);
obuf[len] = 0;
fmtstrcpy(f, obuf);
return 0;
}
ilen = f->prec;
f->prec = 0;
f->flags &= ~FmtPrec;
len = 2*ilen + 1;
if(len > sizeof(obuf)){
buf = malloc(len);
if(buf == nil)
goto error;
} else
buf = obuf;
/* convert */
out = buf;
rv = enc16(out, len, b, ilen);
if(rv < 0)
goto error;
fmtstrcpy(f, buf);
if(buf != obuf)
free(buf);
return 0;
error:
return fmtstrcpy(f, "<encodefmt>");
}
void*
emalloc(int size)
{
@ -2048,7 +2036,7 @@ rrfree(RR *rp)
case Ttxt:
while(t = rp->txt){
rp->txt = t->next;
free(t->p);
free(t->data);
memset(t, 0, sizeof *t); /* cause trouble */
free(t);
}

View file

@ -251,7 +251,7 @@ struct Null
struct Txt
{
Txt *next;
char *p;
Block;
};
/*
@ -436,6 +436,7 @@ extern char *trace;
extern int traceactivity;
extern char *zonerefreshprogram;
#pragma varargck type "\\" uchar*
#pragma varargck type "R" RR*
#pragma varargck type "Q" RR*
@ -448,6 +449,7 @@ extern Lock dnlock;
void abort(); /* char*, ... */;
void addserver(Server**, char*);
int bslashfmt(Fmt*);
Server* copyserverlist(Server*);
void db2cache(int);
void dnage(DN*);