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Code Issues Releases Wiki Activity

Resolved blocked domain names

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This commit is contained in:
M66B 2017-03-04 09:26:46 +01:00
parent 2be06c43f3
commit 506a455f54
3 changed files with 76 additions and 40 deletions
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84
app/src/main/jni/netguard/dns.c
View file

@ -60,15 +60,16 @@ int32_t get_qname(const uint8_t *data, const size_t datalen, uint16_t off, char
return (c ? off : ptr);
}
void parse_dns_response(const struct arguments *args, const uint8_t *data, const size_t datalen) {
if (datalen < sizeof(struct dns_header) + 1) {
log_android(ANDROID_LOG_WARN, "DNS response length %d", datalen);
void parse_dns_response(const struct arguments *args, const struct udp_session *u,
const uint8_t *data, size_t *datalen) {
if (*datalen < sizeof(struct dns_header) + 1) {
log_android(ANDROID_LOG_WARN, "DNS response length %d", *datalen);
return;
}
// Check if standard DNS query
// TODO multiple qnames
const struct dns_header *dns = (struct dns_header *) data;
struct dns_header *dns = (struct dns_header *) data;
int qcount = ntohs(dns->q_count);
int acount = ntohs(dns->ans_count);
if (dns->qr == 1 && dns->opcode == 0 && qcount > 0 && acount > 0) {
@ -77,42 +78,40 @@ void parse_dns_response(const struct arguments *args, const uint8_t *data, const
log_android(ANDROID_LOG_WARN, "DNS response qcount %d acount %d", qcount, acount);
// http://tools.ietf.org/html/rfc1035
int32_t off = sizeof(struct dns_header);
uint16_t qtype;
uint16_t qclass;
char qname[DNS_QNAME_MAX + 1];
char name[DNS_QNAME_MAX + 1];
int32_t off = sizeof(struct dns_header);
for (int q = 0; q < qcount; q++) {
off = get_qname(data, datalen, (uint16_t) off, name);
if (off > 0 && off + 4 <= datalen) {
uint16_t qtype = ntohs(*((uint16_t *) (data + off)));
uint16_t qclass = ntohs(*((uint16_t *) (data + off + 2)));
// TODO multiple qnames?
for (int q = 0; q < 1; q++) {
off = get_qname(data, *datalen, (uint16_t) off, qname);
if (off > 0 && off + 4 <= *datalen) {
qtype = ntohs(*((uint16_t *) (data + off)));
qclass = ntohs(*((uint16_t *) (data + off + 2)));
log_android(ANDROID_LOG_DEBUG,
"DNS question %d qtype %d qclass %d qname %s",
q, qtype, qclass, name);
"DNS question %d qtype %d qclass %d qname %s", q, qtype, qclass, qname);
off += 4;
// TODO multiple qnames?
if (q == 0)
strcpy(qname, name);
}
else {
log_android(ANDROID_LOG_WARN,
"DNS response Q invalid off %d datalen %d",
off, datalen);
"DNS response Q invalid off %d datalen %d", off, *datalen);
return;
}
}
char name[DNS_QNAME_MAX + 1];
for (int a = 0; a < acount; a++) {
off = get_qname(data, datalen, (uint16_t) off, name);
if (off > 0 && off + 10 <= datalen) {
off = get_qname(data, *datalen, (uint16_t) off, name);
if (off > 0 && off + 10 <= *datalen) {
uint16_t qtype = ntohs(*((uint16_t *) (data + off)));
uint16_t qclass = ntohs(*((uint16_t *) (data + off + 2)));
uint32_t ttl = ntohl(*((uint32_t *) (data + off + 4)));
uint16_t rdlength = ntohs(*((uint16_t *) (data + off + 8)));
off += 10;
if (off + rdlength <= datalen) {
if (off + rdlength <= *datalen) {
if (qclass == DNS_QCLASS_IN &&
(qtype == DNS_QTYPE_A || qtype == DNS_QTYPE_AAAA)) {
@ -138,17 +137,52 @@ void parse_dns_response(const struct arguments *args, const uint8_t *data, const
else {
log_android(ANDROID_LOG_WARN,
"DNS response A invalid off %d rdlength %d datalen %d",
off, rdlength, datalen);
off, rdlength, *datalen);
return;
}
}
else {
log_android(ANDROID_LOG_WARN,
"DNS response A invalid off %d datalen %d",
off, datalen);
"DNS response A invalid off %d datalen %d", off, *datalen);
return;
}
}
if (qcount > 0 && is_domain_blocked(args, qname)) {
dns->qr = 1;
dns->aa = 0;
dns->tc = 0;
dns->rd = 0;
dns->ra = 0;
dns->z = 0;
dns->ad = 0;
dns->cd = 0;
dns->rcode = (uint16_t) args->rcode;
dns->ans_count = 0;
dns->auth_count = 0;
dns->add_count = 0;
*datalen = sizeof(struct dns_header);
char source[INET6_ADDRSTRLEN + 1];
char dest[INET6_ADDRSTRLEN + 1];
if (u->version == 4) {
inet_ntop(AF_INET, &u->saddr.ip4, source, sizeof(source));
inet_ntop(AF_INET, &u->daddr.ip4, dest, sizeof(dest));
}
else {
inet_ntop(AF_INET6, &u->saddr.ip6, source, sizeof(source));
inet_ntop(AF_INET6, &u->daddr.ip6, dest, sizeof(dest));
}
// Log qname
char name[DNS_QNAME_MAX + 40 + 1];
sprintf(name, "qtype %d qname %s rcode %d", qtype, qname, dns->rcode);
jobject objPacket = create_packet(
args, u->version, IPPROTO_UDP, "",
source, ntohs(u->source), dest, ntohs(u->dest),
name, 0, 0);
log_packet(args, objPacket);
}
}
else if (acount > 0)
log_android(ANDROID_LOG_WARN,

3
app/src/main/jni/netguard/netguard.h
View file

@ -350,7 +350,8 @@ void check_udp_socket(const struct arguments *args, const struct epoll_event *ev
int32_t get_qname(const uint8_t *data, const size_t datalen, uint16_t off, char *qname);
void parse_dns_response(const struct arguments *args, const uint8_t *data, const size_t datalen);
void parse_dns_response(const struct arguments *args, const struct udp_session *u,
const uint8_t *data, size_t *datalen);
uint32_t get_send_window(const struct tcp_session *cur);

29
app/src/main/jni/netguard/udp.c
View file

@ -136,7 +136,7 @@ void check_udp_socket(const struct arguments *args, const struct epoll_event *ev
// Process DNS response
if (ntohs(s->udp.dest) == 53)
parse_dns_response(args, buffer, (size_t) bytes);
parse_dns_response(args, &s->udp, buffer, (size_t *) &bytes);
// Forward to tun
if (write_udp(args, &s->udp, buffer, (size_t) bytes) < 0)
@ -338,20 +338,21 @@ jboolean handle_udp(const struct arguments *args,
"DNS query qtype %d qclass %d name %s",
qtype, qclass, qname);
if (check_domain(args, &cur->udp, data, datalen, qclass, qtype, qname)) {
// Log qname
char name[DNS_QNAME_MAX + 40 + 1];
sprintf(name, "qtype %d qname %s", qtype, qname);
jobject objPacket = create_packet(
args, version, IPPROTO_UDP, "",
source, ntohs(cur->udp.source), dest, ntohs(cur->udp.dest),
name, 0, 0);
log_packet(args, objPacket);
if (0)
if (check_domain(args, &cur->udp, data, datalen, qclass, qtype, qname)) {
// Log qname
char name[DNS_QNAME_MAX + 40 + 1];
sprintf(name, "qtype %d qname %s", qtype, qname);
jobject objPacket = create_packet(
args, version, IPPROTO_UDP, "",
source, ntohs(cur->udp.source), dest, ntohs(cur->udp.dest),
name, 0, 0);
log_packet(args, objPacket);
// Session done
cur->udp.state = UDP_FINISHING;
return 0;
}
// Session done
cur->udp.state = UDP_FINISHING;
return 0;
}
}
}