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resolver: bound and terminate DNS address lists #90

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Merged
patrick-irc merged 1 commit into from
Oct 11, 2026
Merged

resolver: bound and terminate DNS address lists #90

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30 changes: 23 additions & 7 deletions ircd/res.c
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Original file line number Diff line number Diff line change
Expand Up @@ -574,15 +574,17 @@ static int proc_answer(ResRQ *rptr, HEADER *hptr, char *buf, char *eob)
Reg char *cp, **alias;
Reg struct hent *hp;
int class, type, dlen, len, ans = 0, n;
struct IN_ADDR dr, *adr;
struct IN_ADDR dr, *adr, *adr_end;

cp = buf + sizeof(HEADER);
hp = (struct hent *)&(rptr->he);
adr = &hp->h_addr;
while (WHOSTENTP(adr->S_ADDR))
/* h_addr_list is zero-terminated: reserve its final slot. */
adr = hp->h_addr_list;
adr_end = &hp->h_addr_list[MAXADDRS - 1];
while (adr < adr_end && WHOSTENTP(adr->S_ADDR))
adr++;
alias = hp->h_aliases;
while (*alias)
while (alias < &hp->h_aliases[MAXALIASES - 1] && *alias)
alias++;
#if defined(SOLARIS_2) && !defined(__GNUC__) /* brain damaged compiler it seems */
for (; hptr->qdcount > 0; hptr->qdcount--)
Expand Down Expand Up @@ -659,6 +661,15 @@ static int proc_answer(ResRQ *rptr, HEADER *hptr, char *buf, char *eob)
dlen, hostbuf));
return -2;
}
/* Never overwrite the reserved zero-terminator. */
if (adr >= adr_end)
{
sendto_flag(SCH_ERROR,
"Too many IP addresses returned for %s",
hostbuf);
cp += dlen;
break;
}
hp->h_length = dlen;
if (ans == 1)
hp->h_addrtype = (class == C_IN) ?
Expand Down Expand Up @@ -699,6 +710,8 @@ static int proc_answer(ResRQ *rptr, HEADER *hptr, char *buf, char *eob)
}
ans++;
adr++;
/* adr is at most adr_end after the checked insertion. */
bzero((char *)adr, sizeof(*adr));
cp += dlen;
break;
case T_PTR :
Expand Down Expand Up @@ -934,7 +947,8 @@ struct hostent *get_res(char *lp)
{
last->he.h_name = rptr->he.h_name;
rptr->he.h_name = NULL;
for (a = 0; rptr->he.h_aliases[a]; a++)
for (a = 0; a < MAXALIASES - 1 &&
rptr->he.h_aliases[a]; a++)
{
Debug((DEBUG_DNS, "Copied CNAME %s for %s",
rptr->he.h_aliases[a],
Expand Down Expand Up @@ -1175,7 +1189,8 @@ static void update_list(ResRQ *rptr, aCache *cachep)
/*
* Do the same again for IP#'s.
*/
for (j = 0; WHOSTENTP(rptr->he.h_addr_list[j].S_ADDR); j++)
for (j = 0; j < MAXADDRS - 1 &&
WHOSTENTP(rptr->he.h_addr_list[j].S_ADDR); j++)
{
s = (char *)rptr->he.h_addr_list[j].S_ADDR;
for (i = 0; (t = cp->he.h_addr_list[i]); i++)
Expand Down Expand Up @@ -1396,7 +1411,8 @@ static aCache *make_cache(ResRQ *rptr)
* used for search) when the reply is for a PTR request.
* The "new" thing we get with PTR is the hostname. --fiction
*/
for (i = 0; WHOSTENTP(rptr->he.h_addr_list[i].S_ADDR); i++)
for (i = 0; i < MAXADDRS - 1 &&
WHOSTENTP(rptr->he.h_addr_list[i].S_ADDR); i++)
{
if ((cp = find_cache_number(rptr,
(char *)(rptr->he.h_addr_list[i].S_ADDR)
Expand Down
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