udhnssnoop: move the code directly into the repo

Signed-off-by: John Crispin <john@phrozen.org>

feeds/ucentral/udnssnoop/Makefile

@@ -6,12 +6,6 @@ PKG_RELEASE:=1
 PKG_LICENSE:=GPL-2.0
 PKG_MAINTAINER:=John Crispin <john@phrozen.org>
 
-PKG_SOURCE_URL=https://github.com/blogic/udnssnoop.git
-PKG_MIRROR_HASH:=afd17cc6aed4a151bc0f437b84491d751932a39f93f429418200e9e8be53dfad
-PKG_SOURCE_PROTO:=git
-PKG_SOURCE_DATE:=2021-04-12
-PKG_SOURCE_VERSION:=67e1e5f0bfc12222aa59c54e7066b1c00a680e56
-
 include $(INCLUDE_DIR)/package.mk
 include $(INCLUDE_DIR)/cmake.mk
 

feeds/ucentral/udnssnoop/src/.gitignore

@@ -0,0 +1,4 @@
+CMakeCache.txt
+CMakeFiles/
+cmake_install.cmake
+udnssnoop

feeds/ucentral/udnssnoop/src/CMakeLists.txt

@@ -0,0 +1,16 @@
+cmake_minimum_required(VERSION 2.6)
+
+PROJECT(udnssnoop C)
+INCLUDE(GNUInstallDirs)
+ADD_DEFINITIONS(-Os -ggdb -Wall -Werror --std=gnu99 -Wmissing-declarations)
+
+SET(CMAKE_SHARED_LIBRARY_LINK_C_FLAGS "")
+
+SET(SOURCES main.c dns.c)
+SET(LIBS ubox ubus resolv)
+
+ADD_EXECUTABLE(udnssnoop ${SOURCES})
+TARGET_LINK_LIBRARIES(udnssnoop ${LIBS})
+INSTALL(TARGETS udnssnoop
+	RUNTIME DESTINATION ${CMAKE_INSTALL_SBINDIR}
+)

feeds/ucentral/udnssnoop/src/dns.c

@@ -0,0 +1,215 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+
+#include "dns.h"
+
+static char name_buffer[MAX_NAME_LEN + 1];
+
+static int
+scan_name(const uint8_t *buffer, int len)
+{
+	int offset = 0;
+
+	while (len && (*buffer != '\0')) {
+		int l = *buffer;
+
+		if (IS_COMPRESSED(l))
+			return offset + 2;
+
+		if (l + 1 > len) return -1;
+		len -= l + 1;
+		offset += l + 1;
+		buffer += l + 1;
+	}
+
+	if (!len || !offset || (*buffer != '\0'))
+		return -1;
+
+	return offset + 1;
+}
+
+static struct dns_header*
+dns_consume_header(uint8_t **data, int *len)
+{
+	struct dns_header *h = (struct dns_header *) *data;
+
+	if (*len < sizeof(struct dns_header))
+		return NULL;
+
+	h->id = be16_to_cpu(h->id);
+	h->flags = be16_to_cpu(h->flags);
+	h->questions = be16_to_cpu(h->questions);
+	h->answers = be16_to_cpu(h->answers);
+	h->authority = be16_to_cpu(h->authority);
+	h->additional = be16_to_cpu(h->additional);
+
+	*len -= sizeof(struct dns_header);
+	*data += sizeof(struct dns_header);
+
+	return h;
+}
+
+static struct dns_question*
+dns_consume_question(uint8_t **data, int *len)
+{
+	struct dns_question *q = (struct dns_question *) *data;
+
+	if (*len < sizeof(struct dns_question))
+		return NULL;
+
+	q->type = be16_to_cpu(q->type);
+	q->class = be16_to_cpu(q->class);
+
+	*len -= sizeof(struct dns_question);
+	*data += sizeof(struct dns_question);
+
+	return q;
+}
+
+static struct dns_answer*
+dns_consume_answer(uint8_t **data, int *len)
+{
+	struct dns_answer *a = (struct dns_answer *) *data;
+
+	if (*len < sizeof(struct dns_answer))
+		return NULL;
+
+	a->type = be16_to_cpu(a->type);
+	a->class = be16_to_cpu(a->class);
+	a->ttl = be32_to_cpu(a->ttl);
+	a->rdlength = be16_to_cpu(a->rdlength);
+
+	*len -= sizeof(struct dns_answer);
+	*data += sizeof(struct dns_answer);
+
+	return a;
+}
+
+static char *
+dns_consume_name(const uint8_t *base, int blen, uint8_t **data, int *len)
+{
+	int nlen = scan_name(*data, *len);
+
+	if (nlen < 1)
+		return NULL;
+
+	if (dn_expand(base, base + blen, *data, name_buffer, MAX_NAME_LEN) < 0) {
+		perror("dns_consume_name/dn_expand");
+		return NULL;
+	}
+
+	*len -= nlen;
+	*data += nlen;
+
+	return name_buffer;
+}
+
+static int
+parse_answer(uint8_t *buffer, int len, uint8_t **b, int *rlen)
+{
+	char *name = dns_consume_name(buffer, len, b, rlen);
+	struct dns_answer *a;
+	uint8_t *rdata;
+	char ipbuf[33];
+
+	if (*rlen < 0) {
+		fprintf(stderr, "dropping: bad answer - bad length\n");
+		return -1;
+	}
+
+	a = dns_consume_answer(b, rlen);
+	if (!a) {
+		fprintf(stderr, "dropping: bad answer - bad buffer\n");
+		return -1;
+	}
+
+	if (!name) {
+		return 0;
+	}
+
+	if ((a->class & ~CLASS_FLUSH) != CLASS_IN) {
+		fprintf(stderr, "dropping: class\n");
+		return -1;
+	}
+
+	rdata = *b;
+	if (a->rdlength > *rlen) {
+		fprintf(stderr, "dropping: bad answer - bad rlen\n");
+		return -1;
+	}
+
+	*rlen -= a->rdlength;
+	*b += a->rdlength;
+
+	switch (a->type) {
+	case TYPE_A:
+		if (a->rdlength != 4)
+			return 0;
+
+		if (!inet_ntop(AF_INET, rdata, ipbuf, sizeof(ipbuf)))
+			return 0;
+		break;
+
+	case TYPE_AAAA:
+		if (a->rdlength != 16)
+			return 0;
+
+		if (!inet_ntop(AF_INET6, rdata, ipbuf, sizeof(ipbuf)))
+			return 0;
+		break;
+
+	default:
+		return 0;
+	}
+
+	ubus_notify_qosify(name, ipbuf, a->type, a->ttl);
+	printf("%s %s %" PRIu32 "\n", name, ipbuf, a->ttl);
+
+	return 0;
+}
+
+void
+dns_handle_packet(uint8_t *buffer, int len)
+{
+	struct dns_header *h;
+	uint8_t *b = buffer;
+	int rlen = len;
+
+	h = dns_consume_header(&b, &rlen);
+	if (!h) {
+		fprintf(stderr, "dropping: bad header\n");
+		return;
+	}
+
+	if (!(h->flags & FLAG_RESPONSE))
+		return;
+
+	if (!h->answers)
+		return;
+
+	while (h->questions-- > 0) {
+		char *name = dns_consume_name(buffer, len, &b, &rlen);
+		struct dns_question *q;
+
+		if (!name || rlen < 0)
+			return;
+
+		q = dns_consume_question(&b, &rlen);
+		if (!q) {
+			fprintf(stderr, "dropping: bad question\n");
+			return;
+		}
+	}
+
+	while (h->answers-- > 0)
+		if (parse_answer(buffer, len, &b, &rlen))
+			return;
+
+/*	while (h->authority-- > 0)
+		if (parse_answer(buffer, len, &b, &rlen))
+			return;
+
+	while (h->additional-- > 0)
+		if (parse_answer(buffer, len, &b, &rlen))
+			return;
+*/
+}

feeds/ucentral/udnssnoop/src/dns.h

@@ -0,0 +1,86 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+
+#ifndef _DNS_H__
+#define _DNS_H__
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <inttypes.h>
+#include <netinet/ip.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+#include <linux/if_ether.h>
+#include <linux/filter.h>
+#include <linux/udp.h>
+#include <netinet/ip6.h>
+#include <arpa/inet.h>
+#include <arpa/nameser.h>
+#include <resolv.h>
+
+#include <libubox/avl-cmp.h>
+#include <libubox/utils.h>
+#include <libubox/uloop.h>
+#include <libubox/ulog.h>
+#include <libubus.h>
+#include <uci.h>
+#include <uci_blob.h>
+
+#define FLAG_RESPONSE		0x8000
+#define FLAG_AUTHORATIVE	0x0400
+
+#define TYPE_A			0x0001
+#define TYPE_PTR		0x000C
+#define TYPE_TXT		0x0010
+#define TYPE_AAAA		0x001c
+#define TYPE_SRV		0x0021
+#define TYPE_ANY		0x00ff
+
+#define IS_COMPRESSED(x)	((x & 0xc0) == 0xc0)
+
+#define CLASS_FLUSH		0x8000
+#define CLASS_UNICAST		0x8000
+#define CLASS_IN		0x0001
+
+#define MAX_NAME_LEN            8096
+#define MAX_DATA_LEN            8096
+
+struct vlan_hdr {
+	uint16_t h_vlan_TCI;
+	uint16_t h_vlan_encapsulated_proto;
+};
+
+struct dns_header {
+	uint16_t id;
+	uint16_t flags;
+	uint16_t questions;
+	uint16_t answers;
+	uint16_t authority;
+	uint16_t additional;
+} __attribute__((packed));
+
+struct dns_srv_data {
+	uint16_t priority;
+	uint16_t weight;
+	uint16_t port;
+} __attribute__((packed));
+
+struct dns_answer {
+	uint16_t type;
+	uint16_t class;
+	uint32_t ttl;
+	uint16_t rdlength;
+} __attribute__((packed));
+
+struct dns_question {
+	uint16_t type;
+	uint16_t class;
+} __attribute__((packed));
+
+void dns_handle_packet(uint8_t *buffer, int len);
+void ubus_notify_qosify(char *name, char *address, int type, int ttl);
+
+#endif

feeds/ucentral/udnssnoop/src/main.c

@@ -0,0 +1,282 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+
+/* code is derived from hapd proxy_arp snooping */
+
+#include "dns.h"
+
+ /* sudo tcpdump -s 3000 -dd greater 96 and '(ip or ip6)' and '(udp or tcp)' and '(port 53)' */
+static struct sock_filter dns_sock_filter_insns[] = {
+	{ 0x80, 0, 0, 0x00000000 },
+	{ 0x35, 0, 19, 0x00000060 },
+	{ 0x28, 0, 0, 0x0000000c },
+	{ 0x15, 0, 9, 0x00000800 },
+	{ 0x30, 0, 0, 0x00000017 },
+	{ 0x15, 0, 15, 0x00000011 },
+	{ 0x28, 0, 0, 0x00000014 },
+	{ 0x45, 13, 0, 0x00001fff },
+	{ 0xb1, 0, 0, 0x0000000e },
+	{ 0x48, 0, 0, 0x0000000e },
+	{ 0x15, 9, 0, 0x00000035 },
+	{ 0x48, 0, 0, 0x00000010 },
+	{ 0x15, 7, 8, 0x00000035 },
+	{ 0x15, 0, 7, 0x000086dd },
+	{ 0x30, 0, 0, 0x00000014 },
+	{ 0x15, 0, 5, 0x00000011 },
+	{ 0x28, 0, 0, 0x00000036 },
+	{ 0x15, 2, 0, 0x00000035 },
+	{ 0x28, 0, 0, 0x00000038 },
+	{ 0x15, 0, 1, 0x00000035 },
+	{ 0x6, 0, 0, 0x00000bb8 },
+	{ 0x6, 0, 0, 0x00000000 },
+};
+
+static const struct sock_fprog sock_filter = {
+	.len = ARRAY_SIZE(dns_sock_filter_insns),
+	.filter = dns_sock_filter_insns,
+};
+
+static struct ubus_auto_conn conn;
+static struct uloop_fd fd;
+static struct blob_buf b;
+static char *ifname;
+static int qosify;
+
+static struct ubus_object_type ubus_object_type = {
+	.name = "dnssnoop"
+};
+
+static void ubus_state_handler(struct ubus_context *ctx, struct ubus_object *obj)
+{
+}
+
+struct ubus_object ubus_object = {
+	.name = "dnssnoop",
+	.type = &ubus_object_type,
+	.subscribe_cb = ubus_state_handler,
+};
+
+
+static int
+proto_is_vlan(uint16_t h_proto)
+{
+	return !!(h_proto == ETH_P_8021Q ||
+		  h_proto == ETH_P_8021AD);
+}
+
+static int
+consume_buffer(uint8_t **buf, int *len, int size)
+{
+	if (size > *len)
+		return -1;
+
+	*buf += size;
+	*len -= size;
+
+	return 0;
+}
+
+static void
+packet_handle(uint8_t *buf, int len)
+{
+	struct ethhdr *eth = (struct ethhdr *)buf;
+	uint16_t h_proto;
+
+	if (consume_buffer(&buf, &len, sizeof(*eth)))
+		return;
+
+	h_proto = eth->h_proto;
+
+	if (proto_is_vlan(ntohs(h_proto))) {
+		struct vlan_hdr *vlanh = (struct vlan_hdr *)buf;
+
+		if (consume_buffer(&buf, &len, sizeof(struct vlan_hdr)))
+			return;
+
+		h_proto = vlanh->h_vlan_encapsulated_proto;
+	}
+
+	switch (ntohs(eth->h_proto)) {
+	case ETH_P_IP:
+		if (consume_buffer(&buf, &len, sizeof(struct ip)))
+			return;
+		break;
+	case ETH_P_IPV6:
+		if (consume_buffer(&buf, &len, sizeof(struct ip6_hdr)))
+			return;
+		break;
+	default:
+		return;
+	}
+
+	if (consume_buffer(&buf, &len, sizeof(struct udphdr)))
+		return;
+
+	dns_handle_packet(buf, len);
+}
+
+static void
+socket_fd_cb(struct uloop_fd *fd, unsigned int events)
+{
+	uint8_t buf[8192];
+
+	do {
+		int len = recvfrom(fd->fd, buf, sizeof(buf), MSG_DONTWAIT, NULL, NULL);
+
+		if (len <= 0) {
+			switch (errno) {
+			case EINTR:
+			case EAGAIN:
+				return;
+			default:
+				exit(1);
+			}
+			break;
+		}
+		packet_handle(buf, len);
+	} while (true);
+}
+
+static int
+socket_open(void)
+{
+	int sock;
+
+	sock = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
+	if (sock == -1) {
+		ULOG_ERR("failed to open socket on %s\n", ifname);
+		return -1;
+	}
+
+	if (setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname))) {
+		ULOG_ERR("failed to bind socket to %s\n", ifname);
+		close(sock);
+		return -1;
+	}
+
+	if (setsockopt(sock, SOL_SOCKET, SO_ATTACH_FILTER,
+		       &sock_filter, sizeof(struct sock_fprog))) {
+		ULOG_ERR("failed to attach filter to %s\n", ifname);
+		close(sock);
+		return -1;
+	}
+
+	return sock;
+}
+
+static void
+snoop_start(void)
+{
+	int sock = socket_open();
+	if (sock == -1) {
+		ULOG_ERR("failed to open socket on %s\n", ifname);
+		return;
+	}
+	fd.cb = socket_fd_cb;
+	fd.fd = sock;
+	uloop_fd_add(&fd, ULOOP_READ);
+}
+
+void
+ubus_notify_qosify(char *name, char *address, int type, int ttl)
+{
+	if (!qosify)
+		return;
+
+	blob_buf_init(&b, 0);
+	switch (type) {
+	case TYPE_AAAA:
+		blobmsg_add_string(&b, "type", "AAAA");
+		break;
+	case TYPE_A:
+		blobmsg_add_string(&b, "type", "A");
+		break;
+	default:
+		return;
+	}
+	blobmsg_add_string(&b, "name", name);
+	blobmsg_add_string(&b, "address", address);
+        blobmsg_add_u32(&b, "ttl", ttl);
+
+	ubus_invoke(&conn.ctx, qosify, "add_dns_host", b.head, NULL, NULL, 200);
+}
+
+static void
+ubus_handle_status(struct ubus_context *ctx,  struct ubus_event_handler *ev,
+	      const char *type, struct blob_attr *msg)
+{
+	enum {
+		EVENT_ID,
+		EVENT_PATH,
+		__EVENT_MAX
+	};
+
+	static const struct blobmsg_policy status_policy[__EVENT_MAX] = {
+		[EVENT_ID] = { .name = "id", .type = BLOBMSG_TYPE_INT32 },
+		[EVENT_PATH] = { .name = "path", .type = BLOBMSG_TYPE_STRING },
+	};
+
+	struct blob_attr *tb[__EVENT_MAX];
+	uint32_t id;
+	char *path;
+
+	blobmsg_parse(status_policy, __EVENT_MAX, tb, blob_data(msg), blob_len(msg));
+	if (!tb[EVENT_ID] || !tb[EVENT_PATH])
+		return;
+
+	path = blobmsg_get_string(tb[EVENT_PATH]);
+	id = blobmsg_get_u32(tb[EVENT_ID]);
+
+	if (strcmp(path, "qosify"))
+		return;
+
+	if (!strcmp("ubus.object.remove", type))
+		qosify = 0;
+
+	if (!strcmp("ubus.object.add", type))
+		qosify = id;
+}
+
+static void
+ubus_lookup_cb(struct ubus_context *ctx, struct ubus_object_data *obj,
+                    void *priv)
+{
+	if (strcmp(obj->path, "qosify"))
+		return;
+
+	qosify = obj->id;
+}
+
+static struct ubus_event_handler ubus_status_handler = { .cb = ubus_handle_status };
+
+static void
+ubus_connect_handler(struct ubus_context *ctx)
+{
+        ULOG_NOTE("connected to ubus\n");
+	ubus_add_object(ctx, &ubus_object);
+
+	ubus_register_event_handler(ctx, &ubus_status_handler, "ubus.object.add");
+	ubus_register_event_handler(ctx, &ubus_status_handler, "ubus.object.remove");
+
+	ubus_lookup(ctx, NULL, ubus_lookup_cb, NULL);
+}
+
+int
+main(int argc, char **argv)
+{
+	if (argc != 2)
+		return -1;
+
+	ifname = argv[1];
+
+	ulog_open(ULOG_STDIO | ULOG_SYSLOG, LOG_DAEMON, "udnssnoop");
+
+	uloop_init();
+
+	conn.cb = ubus_connect_handler;
+        ubus_auto_connect(&conn);
+	snoop_start();
+	uloop_run();
+	uloop_done();
+
+	return 0;
+}