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rpcd-mod-rrdns: add new rpcd plugin for rapid reverse DNS lookups

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The plugin provides a new ubus procedure "network.rrdns.lookup" which
allows looking up the names of a large chunk of IP addresses at once,
within a fixed global timeout.

This is useful to have a guaranteed maximum query time even if the
local DNS setup is broken or timing out.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>
This commit is contained in:
Jo-Philipp Wich 2017-07-10 18:38:03 +02:00
parent 366707a681
commit 74affdf6f5
4 changed files with 510 additions and 0 deletions
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47
libs/rpcd-mod-rrdns/Makefile Normal file
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#
# Copyright (C) 2016-2017 Jo-Philipp Wich <jo@mein.io>
#
# Licensed under the Apache License, Version 2.0.
#
include $(TOPDIR)/rules.mk
PKG_NAME:=rpcd-mod-rrdns
PKG_VERSION:=20170710
PKG_MAINTAINER:=Jo-Philipp Wich <jo@mein.io>
PKG_LICENSE:=Apache-2.0
PKG_BUILD_PARALLEL:=1
include $(INCLUDE_DIR)/package.mk
include $(INCLUDE_DIR)/cmake.mk
define Build/Prepare
$(INSTALL_DIR) $(PKG_BUILD_DIR)
$(CP) ./src/* $(PKG_BUILD_DIR)/
endef
define Package/rpcd-mod-rrdns
SECTION:=libs
CATEGORY:=Libraries
TITLE:=Rapid reverse DNS rpcd module
DEPENDS:=+rpcd +libubox +libubus
endef
define Package/rpcd-mod-rrdns/description
Provides rapid mass reverse DNS lookup functionality.
endef
define Package/rpcd-mod-rrdns/install
$(INSTALL_DIR) $(1)/usr/lib/rpcd
$(INSTALL_BIN) $(PKG_BUILD_DIR)/rrdns.so $(1)/usr/lib/rpcd/
endef
define Package/rpcd-mod-rrdns/postinst
#!/bin/sh
killall -HUP rpcd 2>/dev/null
exit 0
endef
$(eval $(call BuildPackage,rpcd-mod-rrdns))

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libs/rpcd-mod-rrdns/src/CMakeLists.txt Normal file
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cmake_minimum_required(VERSION 2.6)
PROJECT(rpcd-mod-rrdns C)
ADD_DEFINITIONS(-Os -Wall -Werror --std=gnu99 -g3 -Wmissing-declarations)
SET(CMAKE_SHARED_LIBRARY_LINK_C_FLAGS "")
IF(APPLE)
INCLUDE_DIRECTORIES(/opt/local/include)
LINK_DIRECTORIES(/opt/local/lib)
ENDIF()
FIND_LIBRARY(resolv NAMES resolv)
IF(resolv STREQUAL "LIBS-NOTFOUND")
SET(resolv "")
ENDIF()
ADD_LIBRARY(rpcd-mod-rrdns MODULE rrdns.c)
TARGET_LINK_LIBRARIES(rpcd-mod-rrdns ubox ubus ${resolv})
SET_TARGET_PROPERTIES(rpcd-mod-rrdns PROPERTIES OUTPUT_NAME rrdns PREFIX "")
INSTALL(TARGETS rpcd-mod-rrdns LIBRARY DESTINATION lib)

389
libs/rpcd-mod-rrdns/src/rrdns.c Normal file
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/*
* rrdns - Rapid Reverse DNS lookup plugin for the UBUS RPC server
*
* Copyright (C) 2016 Jo-Philipp Wich <jow@openwrt.org>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <stdint.h>
#include <stdlib.h>
#include <unistd.h>
#include <arpa/nameser.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <resolv.h>
#include <libubox/avl.h>
#include <libubox/usock.h>
#include <libubox/uloop.h>
#include <rpcd/plugin.h>
#include "rrdns.h"
enum {
RPC_L_ADDRS,
RPC_L_TIMEOUT,
RPC_L_SERVER,
RPC_L_PORT,
RPC_L_LIMIT,
__RPC_L_MAX,
};
static const struct blobmsg_policy rpc_lookup_policy[__RPC_L_MAX] = {
[RPC_L_ADDRS] = { .name = "addrs", .type = BLOBMSG_TYPE_ARRAY },
[RPC_L_TIMEOUT] = { .name = "timeout", .type = BLOBMSG_TYPE_INT32 },
[RPC_L_SERVER] = { .name = "server", .type = BLOBMSG_TYPE_STRING },
[RPC_L_PORT] = { .name = "port", .type = BLOBMSG_TYPE_INT16 },
[RPC_L_LIMIT] = { .name = "limit", .type = BLOBMSG_TYPE_INT32 },
};
static int
rrdns_cmp_id(const void *k1, const void *k2, void *ptr)
{
const uint16_t *id1 = k1, *id2 = k2;
return (*id1 - *id2);
}
static int
rrdns_cmp_addr(const void *k1, const void *k2, void *ptr)
{
const struct in6_addr *a1 = k1, *a2 = k2;
return memcmp(a1, a2, sizeof(*a1));
}
static int
rrdns_parse_response(struct rrdns_context *rctx)
{
int n, len;
uint16_t id;
struct rrdns_request *req;
unsigned char res[512];
char buf[INET6_ADDRSTRLEN], dname[MAXDNAME];
HEADER *hdr;
ns_msg handle;
ns_rr rr;
len = recv(rctx->socket.fd, res, sizeof(res), 0);
if (len < sizeof(*hdr))
return -ENODATA;
hdr = (HEADER *)res;
id = hdr->id;
req = avl_find_element(&rctx->request_ids, &id, req, by_id);
if (!req)
return -ENOENT;
avl_delete(&rctx->request_ids, &req->by_id);
if (ns_initparse(res, len, &handle))
return -EINVAL;
for (n = 0; n < ns_msg_count(handle, ns_s_an); n++) {
if (ns_parserr(&handle, ns_s_an, n, &rr))
return -EINVAL;
if (ns_rr_type(rr) != ns_t_ptr)
continue;
if (ns_name_uncompress(ns_msg_base(handle), ns_msg_end(handle),
ns_rr_rdata(rr), dname, sizeof(dname)) < 0)
return -EINVAL;
inet_ntop(req->family, &req->addr, buf, sizeof(buf));
blobmsg_add_string(&rctx->blob, buf, dname);
}
return 0;
}
static int
rrdns_next_query(struct rrdns_context *rctx)
{
const char *addr = NULL, *hex = "0123456789abcdef";
struct rrdns_request *req;
int i, alen, family;
char *p, dname[73];
union {
unsigned char uchar[4];
struct in6_addr in6;
struct in_addr in;
} a = { };
union {
unsigned char buf[512];
HEADER hdr;
} msg;
if (rctx->addr_rem > 0 &&
blob_pad_len(rctx->addr_cur) <= rctx->addr_rem &&
blob_pad_len(rctx->addr_cur) >= sizeof(struct blob_attr)) {
addr = blobmsg_get_string(rctx->addr_cur);
rctx->addr_rem -= blob_pad_len(rctx->addr_cur);
rctx->addr_cur = blob_next(rctx->addr_cur);
}
if (!addr)
return 0;
if (inet_pton(AF_INET6, addr, &a.in6)) {
memset(dname, 0, sizeof(dname));
for (i = 0, p = dname; i < 16; i++) {
*p++ = hex[a.in6.s6_addr[15-i] % 16];
*p++ = '.';
*p++ = hex[a.in6.s6_addr[15-i] / 16];
*p++ = '.';
}
p += snprintf(p, p - dname - 1, "ip6.arpa");
family = AF_INET6;
alen = p - dname;
}
else if (inet_pton(AF_INET, addr, &a.in)) {
family = AF_INET;
alen = snprintf(dname, sizeof(dname), "%u.%u.%u.%u.in-addr.arpa",
a.uchar[3], a.uchar[2], a.uchar[1], a.uchar[0]);
}
else {
return -EINVAL;
}
alen = res_mkquery(QUERY, dname, C_IN, T_PTR, NULL, 0, NULL,
msg.buf, sizeof(msg.buf));
if (alen < 0)
return alen;
if (avl_find(&rctx->request_addrs, &a.in6))
return -ENOTUNIQ;
if (send(rctx->socket.fd, msg.buf, alen, 0) != alen)
return -errno;
req = calloc(1, sizeof(*req));
if (!req)
return -ENOMEM;
req->id = msg.hdr.id;
req->by_id.key = &req->id;
avl_insert(&rctx->request_ids, &req->by_id);
req->family = family;
req->addr.in6 = a.in6;
req->by_addr.key = &req->addr.in6;
avl_insert(&rctx->request_addrs, &req->by_addr);
return 0;
}
static void
rdns_shutdown(struct rrdns_context *rctx)
{
struct rrdns_request *req, *tmp;
uloop_timeout_cancel(&rctx->timeout);
uloop_fd_delete(&rctx->socket);
close(rctx->socket.fd);
ubus_send_reply(rctx->context, &rctx->request, rctx->blob.head);
ubus_complete_deferred_request(rctx->context, &rctx->request,
UBUS_STATUS_OK);
avl_remove_all_elements(&rctx->request_addrs, req, by_addr, tmp)
free(req);
blob_buf_free(&rctx->blob);
free(rctx);
}
static void
rrdns_handle_timeout(struct uloop_timeout *utm)
{
struct rrdns_context *rctx =
container_of(utm, struct rrdns_context, timeout);
rdns_shutdown(rctx);
}
static void
rrdns_handle_response(struct uloop_fd *ufd, unsigned int ev)
{
struct rrdns_context *rctx =
container_of(ufd, struct rrdns_context, socket);
int err = rrdns_parse_response(rctx);
if (err != -ENODATA && err != -ENOENT)
rrdns_next_query(rctx);
if (avl_is_empty(&rctx->request_ids))
rdns_shutdown(rctx);
}
static char *
rrdns_find_nameserver(void)
{
static char line[2*INET6_ADDRSTRLEN];
struct in6_addr in6;
FILE *resolvconf;
char *p;
resolvconf = fopen("/etc/resolv.conf", "r");
if (!resolvconf)
return NULL;
while (fgets(line, sizeof(line), resolvconf)) {
p = strtok(line, " \t");
if (!p || strcmp(p, "nameserver"))
continue;
p = strtok(NULL, " \t\r\n");
if (!p)
continue;
if (!inet_pton(AF_INET6, p, &in6) && !inet_pton(AF_INET, p, &in6))
continue;
fclose(resolvconf);
return p;
}
fclose(resolvconf);
return NULL;
}
static int
rpc_rrdns_lookup(struct ubus_context *ctx, struct ubus_object *obj,
struct ubus_request_data *req, const char *method,
struct blob_attr *msg)
{
int port = 53, limit = RRDNS_DEF_LIMIT, timeout = RRDNS_DEF_TIMEOUT;
struct blob_attr *tb[__RPC_L_MAX];
struct rrdns_context *rctx;
const char *server = NULL;
blobmsg_parse(rpc_lookup_policy, __RPC_L_MAX, tb,
blob_data(msg), blob_len(msg));
if (tb[RPC_L_PORT])
port = blobmsg_get_u16(tb[RPC_L_PORT]);
if (tb[RPC_L_LIMIT])
limit = blobmsg_get_u32(tb[RPC_L_LIMIT]);
if (tb[RPC_L_TIMEOUT])
timeout = blobmsg_get_u32(tb[RPC_L_TIMEOUT]);
if (tb[RPC_L_SERVER])
server = blobmsg_get_string(tb[RPC_L_SERVER]);
if (!tb[RPC_L_ADDRS])
return UBUS_STATUS_INVALID_ARGUMENT;
if (port <= 0)
return UBUS_STATUS_INVALID_ARGUMENT;
if (limit <= 0 || limit > RRDNS_MAX_LIMIT)
return UBUS_STATUS_INVALID_ARGUMENT;
if (timeout <= 0 || timeout > RRDNS_MAX_TIMEOUT)
return UBUS_STATUS_INVALID_ARGUMENT;
if (!server || !*server)
server = rrdns_find_nameserver();
if (!server)
return UBUS_STATUS_NOT_FOUND;
rctx = calloc(1, sizeof(*rctx));
if (!rctx)
return UBUS_STATUS_UNKNOWN_ERROR;
rctx->socket.fd = usock(USOCK_UDP, server, usock_port(port));
if (rctx->socket.fd < 0) {
free(rctx);
return UBUS_STATUS_UNKNOWN_ERROR;
}
rctx->context = ctx;
rctx->addr_cur = blobmsg_data(tb[RPC_L_ADDRS]);
rctx->addr_rem = blobmsg_data_len(tb[RPC_L_ADDRS]);
avl_init(&rctx->request_ids, rrdns_cmp_id, false, NULL);
avl_init(&rctx->request_addrs, rrdns_cmp_addr, false, NULL);
rctx->timeout.cb = rrdns_handle_timeout;
uloop_timeout_set(&rctx->timeout, timeout);
rctx->socket.cb = rrdns_handle_response;
uloop_fd_add(&rctx->socket, ULOOP_READ);
blob_buf_init(&rctx->blob, 0);
while (limit--)
rrdns_next_query(rctx);
ubus_defer_request(ctx, req, &rctx->request);
return UBUS_STATUS_OK;
}
static int
rpc_rrdns_api_init(const struct rpc_daemon_ops *o, struct ubus_context *ctx)
{
static const struct ubus_method rrdns_methods[] = {
UBUS_METHOD("lookup", rpc_rrdns_lookup, rpc_lookup_policy),
};
static struct ubus_object_type rrdns_type =
UBUS_OBJECT_TYPE("rpcd-rrdns", rrdns_methods);
static struct ubus_object obj = {
.name = "network.rrdns",
.type = &rrdns_type,
.methods = rrdns_methods,
.n_methods = ARRAY_SIZE(rrdns_methods),
};
return ubus_add_object(ctx, &obj);
}
struct rpc_plugin rpc_plugin = {
.init = rpc_rrdns_api_init
};

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libs/rpcd-mod-rrdns/src/rrdns.h Normal file
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/*
* rrdns - Rapid Reverse DNS lookup plugin for the UBUS RPC server
*
* Copyright (C) 2016-2017 Jo-Philipp Wich <jo@mein.io>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <libubus.h>
#include <libubox/avl.h>
#include <libubox/uloop.h>
#define RRDNS_MAX_TIMEOUT 5000
#define RRDNS_DEF_TIMEOUT 250
#define RRDNS_MAX_LIMIT 1000
#define RRDNS_DEF_LIMIT 10
struct rrdns_request {
struct avl_node by_id;
struct avl_node by_addr;
uint16_t id;
uint16_t family;
union {
struct in_addr in;
struct in6_addr in6;
} addr;
};
struct rrdns_context {
struct ubus_context *context;
struct ubus_request_data request;
struct uloop_timeout timeout;
struct blob_attr *addr_cur;
int addr_rem;
struct uloop_fd socket;
struct blob_buf blob;
struct avl_tree request_ids;
struct avl_tree request_addrs;
};