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ndb/dns: fix encoding of srv record target

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the target has to be encoded as a domain name (the individual
name components as separate labels followed by . (empty) label),
not as a literal string.

to disable compression, pass nil dictionary to pname().
This commit is contained in:
cinap_lenrek 2018-06-26 19:30:52 +02:00
parent deae5c854b
commit 902eceee63
1 changed files with 37 additions and 34 deletions
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71
sys/src/cmd/ndb/convDNS2M.c
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@ -24,6 +24,7 @@ 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 BYTES(x, n) p = pbytes(p, ep, x, n)
@ -125,42 +126,44 @@ pname(uchar *p, uchar *ep, char *np, Dict *dp)
if(strlen(np) >= Domlen) /* make sure we don't exceed DNS limits */
return ep+1;
last = 0;
last = nil;
while(*np){
/* look through every component in the dictionary for a match */
for(i = 0; i < dp->n; i++)
if(strcmp(np, dp->x[i].name) == 0){
if(ep - p < 2)
return ep+1;
if ((dp->x[i].offset>>8) & 0xc0)
dnslog("convDNS2M: offset too big for "
"DNS packet format");
*p++ = dp->x[i].offset>>8 | 0xc0;
*p++ = dp->x[i].offset;
return p;
}
/* if there's room, enter this name in dictionary */
if(dp->n < Ndict)
if(last){
/* the whole name is already in dp->buf */
last = strchr(last, '.') + 1;
dp->x[dp->n].name = last;
dp->x[dp->n].offset = p - dp->start;
dp->n++;
} else {
/* add to dp->buf */
i = strlen(np);
if(dp->ep + i + 1 < &dp->buf[sizeof dp->buf]){
memmove(dp->ep, np, i);
dp->ep[i] = 0;
dp->x[dp->n].name = dp->ep;
last = dp->ep;
dp->x[dp->n].offset = p - dp->start;
dp->ep += i + 1;
dp->n++;
if(dp != nil){
/* look through every component in the dictionary for a match */
for(i = 0; i < dp->n; i++){
if(strcmp(np, dp->x[i].name) == 0){
if(ep - p < 2)
return ep+1;
if ((dp->x[i].offset>>8) & 0xc0)
break;
*p++ = dp->x[i].offset>>8 | 0xc0;
*p++ = dp->x[i].offset;
return p;
}
}
/* if there's room, enter this name in dictionary */
if(dp->n < Ndict){
if(last != nil){
/* the whole name is already in dp->buf */
last = strchr(last, '.') + 1;
dp->x[dp->n].name = last;
dp->x[dp->n].offset = p - dp->start;
dp->n++;
} else {
/* add to dp->buf */
i = strlen(np);
if(dp->ep + i + 1 < &dp->buf[sizeof dp->buf]){
memmove(dp->ep, np, i);
dp->ep[i] = 0;
dp->x[dp->n].name = dp->ep;
last = dp->ep;
dp->x[dp->n].offset = p - dp->start;
dp->ep += i + 1;
dp->n++;
}
}
}
}
/* put next component into message */
cp = strchr(np, '.');
@ -259,7 +262,7 @@ convRR2M(RR *rp, uchar *p, uchar *ep, Dict *dp)
USHORT(rp->srv->pri);
USHORT(rp->srv->weight);
USHORT(rp->port);
STRING(rp->host->name); /* rfc2782 sez no name compression */
LABEL(rp->host->name); /* rfc2782 sez no name compression */
break;
case Ttxt:
for(t = rp->txt; t != nil; t = t->next)