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-rw-r--r--libc/inet/resolv.c234
1 files changed, 152 insertions, 82 deletions
diff --git a/libc/inet/resolv.c b/libc/inet/resolv.c
index 718d71a0d..7abc9b506 100644
--- a/libc/inet/resolv.c
+++ b/libc/inet/resolv.c
@@ -7,6 +7,31 @@
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
+ *
+ * 5-Oct-2000 W. Greathouse wgreathouse@smva.com
+ * Fix memory leak and memory corruption.
+ * -- Every name resolution resulted in
+ * a new parse of resolv.conf and new
+ * copy of nameservers allocated by
+ * strdup.
+ * -- Every name resolution resulted in
+ * a new read of resolv.conf without
+ * resetting index from prior read...
+ * resulting in exceeding array bounds.
+ *
+ * Limit nameservers read from resolv.conf
+ *
+ * Add "search" domains from resolv.conf
+ *
+ * Some systems will return a security
+ * signature along with query answer for
+ * dynamic DNS entries.
+ * -- skip/ignore this answer
+ *
+ * Include arpa/nameser.h for defines.
+ *
+ * General cleanup
+ *
*/
#include <string.h>
@@ -21,11 +46,13 @@
#include <unistd.h>
#include <cfgfile.h>
#include <resolv.h>
+#include <arpa/nameser.h>
-#define DNS_SERVICE 53
#define MAX_RECURSE 5
#define REPLY_TIMEOUT 10
#define MAX_RETRIES 15
+#define MAX_SERVERS 3
+#define MAX_SEARCH 4
#undef DEBUG
#ifdef DEBUG
@@ -37,7 +64,7 @@
#ifdef L_encodeh
int encode_header(struct resolv_header *h, unsigned char *dest, int maxlen)
{
- if (maxlen < 12)
+ if (maxlen < HFIXEDSZ)
return -1;
dest[0] = (h->id & 0xff00) >> 8;
@@ -55,7 +82,7 @@ int encode_header(struct resolv_header *h, unsigned char *dest, int maxlen)
dest[10] = (h->arcount & 0xff00) >> 8;
dest[11] = (h->arcount & 0x00ff) >> 0;
- return 12;
+ return HFIXEDSZ;
}
#endif
@@ -75,7 +102,7 @@ int decode_header(unsigned char *data, struct resolv_header *h)
h->nscount = (data[8] << 8) | data[9];
h->arcount = (data[10] << 8) | data[11];
- return 12;
+ return HFIXEDSZ;
}
#endif
@@ -129,7 +156,10 @@ int decode_dotted(const unsigned char *data, int offset,
if (!data)
return -1;
- while ((measure && total++), (l = data[offset++])) {
+ while ((l = data[offset++])) {
+
+ if (measure && total++)
+ break;
if ((l & 0xc0) == (0xc0)) {
if (measure)
@@ -217,7 +247,7 @@ int decode_question(unsigned char *message, int offset,
char temp[256];
int i;
- i = decode_dotted(message, offset, temp, 256);
+ i = decode_dotted(message, offset, temp, sizeof(temp));
if (i < 0)
return i;
@@ -256,7 +286,7 @@ int encode_answer(struct resolv_answer *a, unsigned char *dest, int maxlen)
dest += i;
maxlen -= i;
- if (maxlen < (10 + a->rdlength))
+ if (maxlen < (RRFIXEDSZ+a->rdlength))
return -1;
*dest++ = (a->atype & 0xff00) >> 8;
@@ -271,7 +301,7 @@ int encode_answer(struct resolv_answer *a, unsigned char *dest, int maxlen)
*dest++ = (a->rdlength & 0x00ff) >> 0;
memcpy(dest, a->rdata, a->rdlength);
- return i + 10 + a->rdlength;
+ return i + RRFIXEDSZ + a->rdlength;
}
#endif
@@ -282,7 +312,7 @@ int decode_answer(unsigned char *message, int offset,
char temp[256];
int i;
- i = decode_dotted(message, offset, temp, 256);
+ i = decode_dotted(message, offset, temp, sizeof(temp));
if (i < 0)
return i;
@@ -299,11 +329,11 @@ int decode_answer(unsigned char *message, int offset,
a->rdlength = (message[0] << 8) | message[1];
message += 2;
a->rdata = message;
- a->rdoffset = offset + i + 10;
+ a->rdoffset = offset + i + RRFIXEDSZ;
DPRINTF("i=%d,rdlength=%d\n", i, a->rdlength);
- return i + 10 + a->rdlength;
+ return i + RRFIXEDSZ + a->rdlength;
}
#endif
@@ -385,7 +415,7 @@ int form_query(int id, const char *name, int type, unsigned char *packet,
q.dotted = (char *) name;
q.qtype = type;
- q.qclass = 1 /*CLASS_IN */ ;
+ q.qclass = C_IN; /* CLASS_IN */
i = encode_header(&h, packet, maxlen);
if (i < 0)
@@ -411,9 +441,7 @@ int dns_lookup(const char *name, int type, int nscount, const char **nsip,
unsigned char **outpacket, struct resolv_answer *a)
{
static int id = 1;
- int i, j, len;
- int fd;
- int pos;
+ int i, j, len, fd, pos;
static int ns = 0;
struct sockaddr_in sa;
int oldalarm;
@@ -421,17 +449,17 @@ int dns_lookup(const char *name, int type, int nscount, const char **nsip,
struct resolv_header h;
struct resolv_question q;
int retries = 0;
- unsigned char *packet = malloc(512);
+ unsigned char * packet = malloc(PACKETSZ);
+ unsigned char * lookup = malloc(MAXDNAME);
+ int variant = 0;
+ extern int searchdomains;
+ extern const char * searchdomain[MAX_SEARCH];
- if (!packet)
- goto fail1;
+ if (!packet || !lookup || !nscount)
+ goto fail;
DPRINTF("Looking up type %d answer for '%s'\n", type, name);
-
- if (!nscount)
- goto fail1;
-
ns %= nscount;
fd = -1;
@@ -444,10 +472,9 @@ int dns_lookup(const char *name, int type, int nscount, const char **nsip,
fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (fd == -1)
- goto fail2;
-
+ goto fail;
- memset(packet, 0, 512);
+ memset(packet, 0, PACKETSZ);
memset(&h, 0, sizeof(h));
h.id = ++id;
@@ -456,25 +483,32 @@ int dns_lookup(const char *name, int type, int nscount, const char **nsip,
DPRINTF("encoding header\n");
- i = encode_header(&h, packet, 512);
+ i = encode_header(&h, packet, PACKETSZ);
if (i < 0)
- goto fail3;
+ goto fail;
- q.dotted = (char *) name;
+ strncpy(lookup,name,MAXDNAME);
+ if (variant < searchdomains)
+ {
+ strncat(lookup,".", MAXDNAME);
+ strncat(lookup,searchdomain[variant], MAXDNAME);
+ }
+ DPRINTF("lookup name: %s\n", lookup);
+ q.dotted = (char *)lookup;
q.qtype = type;
- q.qclass = 1 /*CLASS_IN */ ;
+ q.qclass = C_IN; /* CLASS_IN */
- j = encode_question(&q, packet + i, 512 - i);
+ j = encode_question(&q, packet+i, PACKETSZ-i);
if (j < 0)
- goto fail3;
+ goto fail;
len = i + j;
DPRINTF("On try %d, sending query to port %d of machine %s\n",
- retries, DNS_SERVICE, nsip[ns]);
+ retries, NAMESERVER_PORT, nsip[ns]);
sa.sin_family = AF_INET;
- sa.sin_port = htons(DNS_SERVICE);
+ sa.sin_port = htons(NAMESERVER_PORT);
sa.sin_addr.s_addr = inet_addr(nsip[ns]);
if (connect(fd, (struct sockaddr *) &sa, sizeof(sa)) == -1) {
@@ -483,7 +517,7 @@ int dns_lookup(const char *name, int type, int nscount, const char **nsip,
goto tryall;
} else
/* retry */
- break;
+ continue;
}
DPRINTF("Transmitting packet of length %d, id=%d, qr=%d\n",
@@ -495,7 +529,7 @@ int dns_lookup(const char *name, int type, int nscount, const char **nsip,
oldalarm = alarm(REPLY_TIMEOUT);
oldhandler = signal(SIGALRM, dns_catch_signal);
- i = recv(fd, packet, 512, 0);
+ i = recv(fd, packet, PACKETSZ, 0);
alarm(0);
signal(SIGALRM, oldhandler);
@@ -508,7 +542,7 @@ int dns_lookup(const char *name, int type, int nscount, const char **nsip,
to next nameserver on queue */
goto again;
- if (i < 12)
+ if (i < HFIXEDSZ)
/* too short ! */
goto again;
@@ -528,10 +562,10 @@ int dns_lookup(const char *name, int type, int nscount, const char **nsip,
if ((h.rcode) || (h.ancount < 1)) {
/* negative result, not present */
- goto tryall;
+ goto again;
}
- pos = 12;
+ pos = HFIXEDSZ;
for (j = 0; j < h.qdcount; j++) {
DPRINTF("Skipping question %d at %d\n", j, pos);
@@ -543,11 +577,21 @@ int dns_lookup(const char *name, int type, int nscount, const char **nsip,
}
DPRINTF("Decoding answer at pos %d\n", pos);
- i = decode_answer(packet, pos, a);
+ for (j=0;j<h.ancount;j++)
+ {
+ i = decode_answer(packet, pos, a);
- if (i < 0) {
+ if (i<0) {
DPRINTF("failed decode %d\n", i);
goto again;
+ }
+ /* For all but T_SIG, accept first answer */
+ if (a->atype != T_SIG)
+ break;
+
+ DPRINTF("skipping T_SIG %d\n", i);
+ free(a->dotted);
+ pos += i;
}
DPRINTF("Answer name = |%s|\n", a->dotted);
@@ -564,28 +608,37 @@ int dns_lookup(const char *name, int type, int nscount, const char **nsip,
tryall:
/* if there are other nameservers, give them a go,
otherwise return with error */
- if (retries >= nscount)
- break;
+ variant = 0;
+ if (retries >= nscount*(searchdomains+1))
+ goto fail;
+
again:
- ns = (ns + 1) % nscount;
- continue;
+ /* if there are searchdomains, try them or fallback as passed */
+ if (variant < searchdomains) {
+ /* next search */
+ variant++;
+ } else {
+ /* next server, first search */
+ ns = (ns + 1) % nscount;
+ variant = 0;
+ }
}
-
-
- fail3:
- close(fd);
- fail2:
- free(packet);
- fail1:
+fail:
+ if (fd != -1)
+ close(fd);
+ if (lookup)
+ free(lookup);
+ if (packet)
+ free(packet);
return -1;
}
#endif
#ifdef L_resolveaddress
-int resolve_address(const char *address,
- int nscount, const char **nsip, struct in_addr *in)
+int resolve_address(const char *address, int nscount,
+ const char **nsip, struct in_addr *in)
{
unsigned char *packet;
struct resolv_answer a;
@@ -596,19 +649,19 @@ int resolve_address(const char *address,
if (!address || !in)
return -1;
- strcpy(temp, address);
+ strncpy(temp, address, sizeof(temp));
for (;;) {
- i = dns_lookup(temp, 1, nscount, nsip, &packet, &a);
+ i = dns_lookup(temp, T_A, nscount, nsip, &packet, &a);
if (i < 0)
return -1;
free(a.dotted);
- if (a.atype == 5) { /* CNAME */
- i = decode_dotted(packet, a.rdoffset, temp, 256);
+ if (a.atype == T_CNAME) { /* CNAME */
+ i = decode_dotted(packet, a.rdoffset, temp, sizeof(temp));
free(packet);
if (i < 0)
@@ -616,7 +669,7 @@ int resolve_address(const char *address,
if (++nest > MAX_RECURSE)
return -1;
continue;
- } else if (a.atype == 1) { /* ADDRESS */
+ } else if (a.atype == T_A) { /* ADDRESS */
free(packet);
break;
} else {
@@ -626,7 +679,7 @@ int resolve_address(const char *address,
}
if (in)
- memcpy(in, a.rdata, 4);
+ memcpy(in, a.rdata, INADDRSZ); /* IPv4 T_A */
return 0;
}
@@ -647,33 +700,33 @@ int resolve_mailbox(const char *address,
return -1;
/* look up mail exchange */
- i = dns_lookup(address, 15, nscount, nsip, &packet, &a);
+ i = dns_lookup(address, T_MX, nscount, nsip, &packet, &a);
- strcpy(temp, address);
+ strncpy(temp, address, sizeof(temp));
if (i >= 0) {
- i = decode_dotted(packet, a.rdoffset + 2, temp, 256);
+ i = decode_dotted(packet, a.rdoffset+2, temp, sizeof(temp));
free(packet);
}
for (;;) {
- i = dns_lookup(temp, 1, nscount, nsip, &packet, &a);
+ i = dns_lookup(temp, T_A, nscount, nsip, &packet, &a);
if (i < 0)
return -1;
free(a.dotted);
- if (a.atype == 5) { /* CNAME */
- i = decode_dotted(packet, a.rdoffset, temp, 256);
+ if (a.atype == T_CNAME) { /* CNAME */
+ i = decode_dotted(packet, a.rdoffset, temp, sizeof(temp));
free(packet);
if (i < 0)
return i;
if (++nest > MAX_RECURSE)
return -1;
continue;
- } else if (a.atype == 1) { /* ADDRESS */
+ } else if (a.atype == T_A) { /* ADDRESS */
free(packet);
break;
} else {
@@ -683,19 +736,23 @@ int resolve_mailbox(const char *address,
}
if (in)
- memcpy(in, a.rdata, 4);
+ memcpy(in, a.rdata, INADDRSZ); /* IPv4 */
return 0;
}
#endif
extern int nameservers;
-extern const char *nameserver[3];
+extern const char * nameserver[MAX_SERVERS];
+extern int searchdomains;
+extern const char * searchdomain[MAX_SEARCH];
#ifdef L_opennameservers
int nameservers;
-const char * nameserver[3];
+const char * nameserver[MAX_SERVERS];
+int searchdomains;
+const char * searchdomain[MAX_SEARCH];
int open_nameservers()
{
@@ -703,14 +760,27 @@ int open_nameservers()
char **arg;
int i;
+ if (nameservers > 0)
+ return 0;
+
if ((fp = fopen("/etc/resolv.conf", "r"))) {
- if ((arg = cfgfind(fp, "nameserver"))) {
- for (i = 1; arg[i]; i++) {
+ if (0 != (arg = cfgfind(fp, "nameserver"))) {
+ for (i=1; arg[i] && nameservers <= MAX_SERVERS; i++) {
nameserver[nameservers++] = strdup(arg[i]);
+ DPRINTF("adding nameserver %s\n",arg[i]);
+ }
+ }
+ if (0 != (arg = cfgfind(fp, "search"))) {
+ for (i=1; arg[i] && searchdomains <= MAX_SEARCH; i++) {
+ searchdomain[searchdomains++] = strdup(arg[i]);
+ DPRINTF("adding search %s\n",arg[i]);
}
}
fclose(fp);
+ } else {
+ DPRINTF("failed to open resolv.conf\n");
}
+ DPRINTF("nameservers = %d\n", nameservers);
return 0;
}
#endif
@@ -720,7 +790,7 @@ void close_nameservers(void)
{
while (nameservers > 0)
- free(nameserver[--nameservers]);
+ free((void*)nameserver[--nameservers]);
}
#endif
@@ -787,12 +857,12 @@ struct hostent *gethostbyname(const char *name)
if (i < 0)
return 0;
- strcpy(namebuf, a.dotted);
+ strncpy(namebuf, a.dotted, sizeof(namebuf));
free(a.dotted);
- if (a.atype == 5) { /* CNAME */
- i = decode_dotted(packet, a.rdoffset, namebuf, 256);
+ if (a.atype == T_CNAME) { /* CNAME */
+ i = decode_dotted(packet, a.rdoffset, namebuf, sizeof(namebuf));
free(packet);
if (i < 0)
@@ -800,7 +870,7 @@ struct hostent *gethostbyname(const char *name)
if (++nest > MAX_RECURSE)
return 0;
continue;
- } else if (a.atype == 1) { /* ADDRESS */
+ } else if (a.atype == T_A) { /* ADDRESS */
memcpy(&in, a.rdata, sizeof(in));
h.h_name = namebuf;
h.h_addrtype = AF_INET;
@@ -850,16 +920,16 @@ struct hostent *gethostbyaddr(const char *addr, int len, int type)
for (;;) {
- i = dns_lookup(namebuf, 12, nameservers, nameserver, &packet, &a);
+ i = dns_lookup(namebuf, T_PTR, nameservers, nameserver, &packet, &a);
if (i < 0)
return 0;
- strcpy(namebuf, a.dotted);
+ strncpy(namebuf, a.dotted, sizeof(namebuf));
free(a.dotted);
- if (a.atype == 5) { /* CNAME */
- i = decode_dotted(packet, a.rdoffset, namebuf, 256);
+ if (a.atype == T_CNAME) { /* CNAME */
+ i = decode_dotted(packet, a.rdoffset, namebuf, sizeof(namebuf));
free(packet);
if (i < 0)
@@ -867,8 +937,8 @@ struct hostent *gethostbyaddr(const char *addr, int len, int type)
if (++nest > MAX_RECURSE)
return 0;
continue;
- } else if (a.atype == 12) { /* ADDRESS */
- i = decode_dotted(packet, a.rdoffset, namebuf, 256);
+ } else if (a.atype == T_PTR) { /* ADDRESS */
+ i = decode_dotted(packet, a.rdoffset, namebuf, sizeof(namebuf));
free(packet);
h.h_name = namebuf;
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-03 17:09:22 +0000