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dnsmasq: add support for monitoring and modifying dns lookup results via ubus

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The monitoring functionality will be used for dns rule support in qosify

Signed-off-by: Felix Fietkau <nbd@nbd.name>
This commit is contained in:
Felix Fietkau 2021-11-08 14:48:36 +01:00
parent 83f1d72dea
commit d8b33dad0b
1 changed files with 270 additions and 0 deletions
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270
package/network/services/dnsmasq/patches/200-ubus_dns.patch Normal file
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@ -0,0 +1,270 @@
--- a/src/dnsmasq.h
+++ b/src/dnsmasq.h
@@ -1564,14 +1564,26 @@ void emit_dbus_signal(int action, struct
/* ubus.c */
#ifdef HAVE_UBUS
+struct blob_attr;
+typedef void (*ubus_dns_notify_cb)(struct blob_attr *msg, void *priv);
+
char *ubus_init(void);
void set_ubus_listeners(void);
void check_ubus_listeners(void);
+void drop_ubus_listeners(void);
+struct blob_buf *ubus_dns_notify_prepare(void);
+int ubus_dns_notify(const char *type, ubus_dns_notify_cb cb, void *priv);
void ubus_event_bcast(const char *type, const char *mac, const char *ip, const char *name, const char *interface);
# ifdef HAVE_CONNTRACK
void ubus_event_bcast_connmark_allowlist_refused(u32 mark, const char *name);
void ubus_event_bcast_connmark_allowlist_resolved(u32 mark, const char *pattern, const char *ip, u32 ttl);
# endif
+#else
+struct blob_buf;
+static inline struct blob_buf *ubus_dns_notify_prepare(void)
+{
+ return NULL;
+}
#endif
/* ipset.c */
--- a/src/rfc1035.c
+++ b/src/rfc1035.c
@@ -13,8 +13,10 @@
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-
#include "dnsmasq.h"
+#ifdef HAVE_UBUS
+#include <libubox/blobmsg.h>
+#endif
int extract_name(struct dns_header *header, size_t plen, unsigned char **pp,
char *name, int isExtract, int extrabytes)
@@ -394,9 +396,64 @@ static int private_net6(struct in6_addr
((u32 *)a)[0] == htonl(0x20010db8); /* RFC 6303 4.6 */
}
+#ifdef HAVE_UBUS
+static void ubus_dns_doctor_cb(struct blob_attr *msg, void *priv)
+{
+ static const struct blobmsg_policy policy = {
+ .name = "address",
+ .type = BLOBMSG_TYPE_STRING,
+ };
+ struct blob_attr *val;
+ char **dest = priv;
+
+ blobmsg_parse(&policy, 1, &val, blobmsg_data(msg), blobmsg_data_len(msg));
+ if (val)
+ *dest = blobmsg_get_string(val);
+}
+
+static bool ubus_dns_doctor(const char *name, int ttl, void *p, int af)
+{
+ struct blob_buf *b;
+ char *addr;
+
+ if (!name)
+ return false;
+
+ b = ubus_dns_notify_prepare();
+ if (!b)
+ return false;
+
+ blobmsg_add_string(b, "name", name);
+
+ blobmsg_add_u32(b, "ttl", ttl);
+
+ blobmsg_add_string(b, "type", af == AF_INET6 ? "AAAA" : "A");
+
+ addr = blobmsg_alloc_string_buffer(b, "address", INET6_ADDRSTRLEN);
+ if (!addr)
+ return false;
+
+ inet_ntop(af, p, addr, INET6_ADDRSTRLEN);
+ blobmsg_add_string_buffer(b);
+
+ addr = NULL;
+ ubus_dns_notify("dns_result", ubus_dns_doctor_cb, &addr);
+
+ if (!addr)
+ return false;
+
+ return inet_pton(af, addr, p) == 1;
+}
+#else
+static bool ubus_dns_doctor(const char *name, int ttl, void *p, int af)
+{
+ return false;
+}
+#endif
+
static unsigned char *do_doctor(unsigned char *p, int count, struct dns_header *header, size_t qlen, int *doctored)
{
- int i, qtype, qclass, rdlen;
+ int i, qtype, qclass, rdlen, ttl;
for (i = count; i != 0; i--)
{
@@ -405,7 +462,7 @@ static unsigned char *do_doctor(unsigned
GETSHORT(qtype, p);
GETSHORT(qclass, p);
- p += 4; /* ttl */
+ GETLONG(ttl, p); /* ttl */
GETSHORT(rdlen, p);
if (qclass == C_IN && qtype == T_A)
@@ -416,6 +473,9 @@ static unsigned char *do_doctor(unsigned
if (!CHECK_LEN(header, p, qlen, INADDRSZ))
return 0;
+ if (ubus_dns_doctor(daemon->namebuff, ttl, p, AF_INET))
+ *doctored = 1;
+
/* alignment */
memcpy(&addr, p, INADDRSZ);
@@ -433,13 +493,22 @@ static unsigned char *do_doctor(unsigned
addr.s_addr &= ~doctor->mask.s_addr;
addr.s_addr |= (doctor->out.s_addr & doctor->mask.s_addr);
/* Since we munged the data, the server it came from is no longer authoritative */
- header->hb3 &= ~HB3_AA;
*doctored = 1;
memcpy(p, &addr, INADDRSZ);
break;
}
}
-
+ else if (qclass == C_IN && qtype == T_AAAA)
+ {
+ if (!CHECK_LEN(header, p, qlen, IN6ADDRSZ))
+ return 0;
+
+ if (ubus_dns_doctor(daemon->namebuff, ttl, p, AF_INET6))
+ *doctored = 1;
+ }
+
+ if (*doctored)
+ header->hb3 &= ~HB3_AA;
if (!ADD_RDLEN(header, p, qlen, rdlen))
return 0; /* bad packet */
}
@@ -563,7 +632,7 @@ int extract_addresses(struct dns_header
cache_start_insert();
/* find_soa is needed for dns_doctor side effects, so don't call it lazily if there are any. */
- if (daemon->doctors || option_bool(OPT_DNSSEC_VALID))
+ if (daemon->doctors || option_bool(OPT_DNSSEC_VALID) || ubus_dns_notify_prepare())
{
searched_soa = 1;
ttl = find_soa(header, qlen, doctored);
--- a/src/ubus.c
+++ b/src/ubus.c
@@ -72,6 +72,14 @@ static struct ubus_object ubus_object =
.subscribe_cb = ubus_subscribe_cb,
};
+static struct ubus_object_type ubus_dns_object_type =
+ { .name = "dnsmasq.dns" };
+
+static struct ubus_object ubus_dns_object = {
+ .name = "dnsmasq.dns",
+ .type = &ubus_dns_object_type,
+};
+
static void ubus_subscribe_cb(struct ubus_context *ctx, struct ubus_object *obj)
{
(void)ctx;
@@ -112,6 +120,8 @@ char *ubus_init()
ubus_object.name = daemon->ubus_name;
ret = ubus_add_object(ubus, &ubus_object);
+ if (!ret)
+ ret = ubus_add_object(ubus, &ubus_dns_object);
if (ret)
{
ubus_destroy(ubus);
@@ -181,6 +191,17 @@ void check_ubus_listeners()
} \
} while (0)
+void drop_ubus_listeners()
+{
+ struct ubus_context *ubus = (struct ubus_context *)daemon->ubus;
+
+ if (!ubus)
+ return;
+
+ ubus_free(ubus);
+ ubus = NULL;
+}
+
static int ubus_handle_metrics(struct ubus_context *ctx, struct ubus_object *obj,
struct ubus_request_data *req, const char *method,
struct blob_attr *msg)
@@ -328,6 +349,50 @@ fail:
} \
} while (0)
+struct blob_buf *ubus_dns_notify_prepare(void)
+{
+ struct ubus_context *ubus = (struct ubus_context *)daemon->ubus;
+
+ if (!ubus || !ubus_dns_object.has_subscribers)
+ return NULL;
+
+ blob_buf_init(&b, 0);
+ return &b;
+}
+
+struct ubus_dns_notify_req {
+ struct ubus_notify_request req;
+ ubus_dns_notify_cb cb;
+ void *priv;
+};
+
+static void dns_notify_cb(struct ubus_notify_request *req, int type, struct blob_attr *msg)
+{
+ struct ubus_dns_notify_req *dreq = container_of(req, struct ubus_dns_notify_req, req);
+
+ dreq->cb(msg, dreq->priv);
+}
+
+int ubus_dns_notify(const char *type, ubus_dns_notify_cb cb, void *priv)
+{
+ struct ubus_context *ubus = (struct ubus_context *)daemon->ubus;
+ struct ubus_dns_notify_req dreq;
+ int ret;
+
+ if (!ubus || !ubus_dns_object.has_subscribers)
+ return 0;
+
+ ret = ubus_notify_async(ubus, &ubus_dns_object, type, b.head, &dreq.req);
+ if (ret)
+ return ret;
+
+ dreq.req.data_cb = dns_notify_cb;
+ dreq.cb = cb;
+ dreq.priv = priv;
+
+ return ubus_complete_request(ubus, &dreq.req.req, 100);
+}
+
void ubus_event_bcast(const char *type, const char *mac, const char *ip, const char *name, const char *interface)
{
struct ubus_context *ubus = (struct ubus_context *)daemon->ubus;
--- a/src/dnsmasq.c
+++ b/src/dnsmasq.c
@@ -1972,6 +1972,10 @@ static void check_dns_listeners(time_t n
daemon->pipe_to_parent = pipefd[1];
}
+#ifdef HAVE_UBUS
+ drop_ubus_listeners();
+#endif
+
/* start with no upstream connections. */
for (s = daemon->servers; s; s = s->next)
s->tcpfd = -1;