Openresty Lua resty DNS domain name resolution

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openresty lua-resty-dns Domain name resolution

                

Official website ：https://github.com/openresty/lua-resty-dns

         

             

                                           

lua-resty-dns Use

            

This library is considered production ready
* lua-resty-dns Already in production 

This Lua library provides a DNS resolver for the ngx_lua nginx module
This Lua library takes advantage of ngx_lua's cosocket API, which 
ensures 100% nonblocking behavior.
* ngx_lua use lua-resty-dns Domain name resolution 
* lua-resty-dns utilize ngx_lua Of cosocket api, Non blocking execution 

Note that at least ngx_lua 0.5.12 or OpenResty 1.2.1.11 is required.
Also, the bit library is also required. If you're using LuaJIT 2.0 
with ngx_lua, then the bit library is already available by default.
* lua-resty-dns Adaptation version ：ngx_lua 0.5.12 And above 、OpenResty 1.2.1.11 And above 

Note that, this library is bundled and enabled by default in the OpenResty bundle.
* lua-resty-dns stay openresty Default binding in 

IMPORTANT: to be able to generate unique ids, the random generator must 
be properly seeded using math.randomseed prior to using this module
*  In order to generate unique id, Random generator （ Use math.randomseed） Prior to the lua-resty-dns perform 

           

new： Create a domain name resolution object

 Grammar format ：r, err = class:new(opts)

Creates a dns.resolver object. Returns nil and a message string on error.
*  Create a domain name resolution object 
*  Create failure , return nil、 Error description information 

It accepts a opts table argument. The following options are supported:
*  receive table Table parameters 
    * nameservers： List of domain name resolution servers 
    a list of nameservers to be used. Each nameserver entry can be either 
a single hostname string or a table holding both the hostname string and 
the port number. The nameserver is picked up by a simple round-robin 
algorithm for each query method call. This option is required.

    * retrans： The total number of domain name resolution retries 
    the total number of times of retransmitting the DNS request when 
receiving a DNS response times out according to the timeout setting. 
Defaults to 5 times. When trying to retransmit the query, the next 
nameserver according to the round-robin algorithm will be picked up.

    * timeout： Timeout time , Unit millisecond 
    the time in milliseconds for waiting for the response for a single 
attempt of request transmission. note that this is ''not'' the maximal 
total waiting time before giving up, the maximal total waiting time can 
be calculated by the expression timeout x retrans. The timeout setting 
can also be changed by calling the set_timeout method. The default 
timeout setting is 2000 milliseconds, or 2 seconds.

    * no_recurse： Whether to disable recursion desired, Default false
    a boolean flag controls whether to disable the "recursion desired" 
(RD) flag in the UDP request. Defaults to false.

    * no_random： Whether to always pick the first domain name parser in the list , Default false（ Random selection ）
    a boolean flag controls whether to randomly pick the nameserver to 
query first, if true will always start with the first nameserver listed. 
Defaults to false

             

query： Domain name resolution

 Grammar format ：answers, err, tries? = r:query(name, options?, tries?)

Performs a DNS standard query to the nameservers specified by the new 
method, and returns all the answer records in an array-like Lua table. 
In case of errors, it will return nil and a string describing the 
error instead.
*  Send a query to the domain name parser , Returns an array of types table data , Represents all parsing results 
*  If you fail , return nil、 Error description information 

If the server returns a non-zero error code, the fields errcode and 
errstr will be set accordingly in the Lua table returned.
*  If the return is not 0 Error code ,errcode、errstr Will also be in table Set in 

Each entry in the answers returned table value is also a hash-like Lua 
table which usually takes some of the following fields:
*  The returned result fields are as follows 
    * name： Resolved resource name 
    The resource record name.

    * type： Resolved resource result type 
    The current resource record type, possible values are 1 (TYPE_A), 5 
(TYPE_CNAME), 28 (TYPE_AAAA), and any other values allowed by RFC 1035.

    * address：ip Address （ipv4、ipv6）
    The IPv4 or IPv6 address in their textual representations when the 
resource record type is either 1 (TYPE_A) or 28 (TYPE_AAAA), respectively
Successive 16-bit zero groups in IPv6 addresses will not be compressed by 
default, if you want that, you need to call the compress_ipv6_addr static 
method instead.

    * section：section identifier 
    The identifier of the section that the current answer record belongs 
to. Possible values are 1 (SECTION_AN), 2 (SECTION_NS), and 3 (SECTION_AR).

    * cname： Alias 
    The (decoded) record data value for CNAME resource records. Only 
present for CNAME records.

    * ttl： Resource results remaining lifetime 
    The time-to-live (TTL) value in seconds for the current resource record.

    *class： Resource result class 
    The current resource record class, possible values are 1 (CLASS_IN) or 
any other values allowed by RFC 1035.

    * preference：MX type The maximum number of results 
    The preference integer number for MX resource records. Only present for 
MX type records.

    * exchange：MX resource Exchange domain name 
    The exchange domain name for MX resource records. Only present for MX 
type records.

    * nsdname：NS type domain name 
    A domain-name which specifies a host which should be authoritative for 
the specified class and domain. Usually present for NS type records.

    * rdata： Unrecognized domain name 
    The raw resource data (RDATA) for resource records that are not recognized.

    * txt：TXT records
    The record value for TXT records. When there is only one character string 
in this record, then this field takes a single Lua string. Otherwise this 
field takes a Lua table holding all the strings.

    * ptrdname：PTR records
    The record value for PTR records


This method also takes an optional options argument table, which takes the following fields:
*  Optional parameters 
    * qtype： Query type 
    The type of the question. Possible values are 1 (TYPE_A), 5 (TYPE_CNAME), 
28 (TYPE_AAAA), or any other QTYPE value specified by RFC 1035 and RFC 3596. 
Default to 1 (TYPE_A).

    * authority_section： authentication section, Default false
    When set to a true value, the answers return value includes the Authority 
section of the DNS response. Default to false.

    * additional_section： additional section, Default false
    When set to a true value, the answers return value includes the Additional 
section of the DNS response. Default to false.


The optional parameter tries can be provided as an empty table, and will be 
returned as a third result. The table will be an array with the error message 
for each (if any) failed try.
* tries The parameter can be an empty table, And it will be returned as the third result parameter 
*  If an error occurs , An error message will be recorded 

When data truncation happens, the resolver will automatically retry using the 
TCP transport mode to query the current nameserver. All TCP connections are 
short lived
*  If data truncation occurs , Will try again 
*  be-all tcp All connections are short connections 

             

tcp_query：tcp Link query

 Grammar format ：answers, err = r:tcp_query(name, options?)

Just like the query method, but enforce the TCP transport mode instead of UDP.
All TCP connections are short lived
*  and query The function of the method is similar to , Compulsory use tcp transport 
*  be-all tcp All connections are short connections 

       

set_timeout： Set timeout

 Grammar format ：r:set_timeout(time)

Overrides the current timeout setting by the time argument in 
milliseconds for all the nameserver peers
*  Set timeout , Unit millisecond 

            

compress_ipv6_addr： Compress ipv6 Address

 Grammar format ：compressed = resty.dns.resolver.compress_ipv6_addr(address)

Compresses the successive 16-bit zero groups in the textual format 
of the IPv6 address
*  Compress ipv6 Address 

#  Example 
    local resolver = require "resty.dns.resolver"
    local compress = resolver.compress_ipv6_addr
    local new_addr = compress("FF01:0:0:0:0:0:0:101")

==> FF01::101

           

expand_ipv6_addr： Restore compressed ipv6 Address

 Grammar format ：expanded = resty.dns.resolver.expand_ipv6_addr(address)

Expands the successive 16-bit zero groups in the textual format 
of the IPv6 address
*  Restore compressed ipv6 Address 

#  Example 
    local resolver = require "resty.dns.resolver"
    local expand = resolver.expand_ipv6_addr
    local new_addr = expand("FF01::101")

==> FF01:0:0:0:0:0:0:101

           

arpa_str： reverse ip Address

 Grammar format ：rpa_record = resty.dns.resolver.arpa_str(address)

Generates the reverse domain name for PTR lookups for both IPv4 and 
IPv6 addresses. Compressed IPv6 addresses will be automatically expanded
*  reverse ipv4、ipv6 Address 

#  Example 
    local resolver = require "resty.dns.resolver"
    local ptr4 = resolver.arpa_str("1.2.3.4")
    local ptr6 = resolver.arpa_str("FF01::101")

==> 4.3.2.1.in-addr.arpa
    1.0.1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.1.0.F.F.ip6.arpa

            

reverse_query：ptr Reverse DNS

 Grammar format ：answers, err = r:reverse_query(address)

Performs a PTR lookup for both IPv4 and IPv6 addresses. This function 
is basically a wrapper for the query command which uses the arpa_str 
command to convert the IP address on the fly
* ptr Reverse DNS 

           

Example

lua_package_path "/path/to/lua-resty-dns/lib/?.lua;;";

server {
    location = /dns {
        content_by_lua_block {
            local resolver = require "resty.dns.resolver"
            local r, err = resolver:new{
                nameservers = {"8.8.8.8", {"8.8.4.4", 53} },
                retrans = 5,  -- 5 retransmissions on receive timeout
                timeout = 2000,  -- 2 sec
                no_random = true, -- always start with first nameserver
            }

            if not r then
                ngx.say("failed to instantiate the resolver: ", err)
                return
            end

            local answers, err, tries = r:query("www.google.com", nil, {})
            if not answers then
                ngx.say("failed to query the DNS server: ", err)
                ngx.say("retry historie:\n  ", table.concat(tries, "\n  "))
                return
            end

            if answers.errcode then
                ngx.say("server returned error code: ", answers.errcode,
                        ": ", answers.errstr)
            end

            for i, ans in ipairs(answers) do
                ngx.say(ans.name, " ", ans.address or ans.cname,
                        " type:", ans.type, " class:", ans.class,
                        " ttl:", ans.ttl)
            end
        }
    }
}

         

                 

                                           

lua-resty-dns Constant

            

TYPE_A      ==>  The A resource record type, equal to the decimal number 1
TYPE_NS     ==>  The NS resource record type, equal to the decimal number 2
TYPE_CNAME  ==>  The CNAME resource record type, equal to the decimal number 5
TYPE_SOA    ==>  The SOA resource record type, equal to the decimal number 6
TYPE_PTR    ==>  The PTR resource record type, equal to the decimal number 12
TYPE_MX     ==>  The MX resource record type, equal to the decimal number 15
TYPE_TXT    ==>  The TXT resource record type, equal to the decimal number 16
TYPE_AAAA   ==>  The AAAA resource record type, equal to the decimal number 28
TYPE_SRV    ==>  The SRV resource record type, equal to the decimal number 33
TYPE_SPF    ==>  The SPF resource record type, equal to the decimal number 99


CLASS_IN    ==>  The Internet resource record type, equal to the decimal number 1

SECTION_AN  ==>  Identifier of the Answer section in the DNS response. 
                 Equal to decimal number 1

SECTION_NS  ==>  Identifier of the Authority section in the DNS response. 
                 Equal to the decimal number 2

SECTION_AR  ==>  Identifier of the Additional section in the DNS response. 
                 Equal to the decimal number 3

            

                       

                                           

Examples of use

            

default.conf

server {
    listen       80;
    server_name  localhost;

    location / {
        root   /usr/local/openresty/nginx/html;
        index  index.html index.htm;
    }

    location /test {
        content_by_lua_block {
            local resolver = require "resty.dns.resolver"
            local cjson = require 'cjson';

            local r, err = resolver:new({
                nameservers = {"8.8.8.8", {"8.8.4.4", 53} },
                retrans = 5,  -- 5 retransmissions on receive timeout
                timeout = 2000,  -- 2 sec
            });

            if not r then
                ngx.say(" Failed to create resolution instance  ==> ", err)
                return
            end

            local answers, err, tries = r:query("www.google.com", nil, {})
            if not answers then
                ngx.say(" Domain name resolution www.google.com Failure  ==> ", err)
                ngx.say(" Retry parsing records  ==> ", table.concat(tries, "\n  "))
                return
            end

            if answers.errcode then
                ngx.say(" Domain name server resolution error  ==> ", answers.errcode, " ==> ", answers.errstr)
            end

            ngx.say(" Analysis results  ==> ", cjson.encode(answers));
            for i, ans in ipairs(answers) do
                ngx.say(ans.name, " ", ans.address or ans.cname,
                        " type:", ans.type, " class:", ans.class,
                        " ttl:", ans.ttl)
            end

            answers, err = r:query("www.baidu.com")
            if not answers then
                ngx.say(" Domain name resolution www.baidu.com Failure  ==> ", err)
                return
            end

            if answers.errcode then
                ngx.say(" Domain name server resolution error  ==> ", answers.errcode, " ==> ", answers.errstr)
            end

            ngx.say("\n Analysis results  ==> ", cjson.encode(answers));
            for i, ans in ipairs(answers) do
                ngx.say(ans.name, " ", ans.address or ans.cname,
                        " type:", ans.type, " class:", ans.class,
                        " ttl:", ans.ttl)
            end

            answers, err = r:reverse_query("www.taobao.com")
            if not answers then
                ngx.say(" Domain name resolution www.taobao.com Failure  ==> ", err)
                return
            end

            if answers.errcode then
                ngx.say(" Domain name server resolution error  ==> ", answers.errcode, " ==> ", answers.errstr)
            end

            ngx.say("\n Analysis results  ==> ", cjson.encode(answers));
            for i, ans in ipairs(answers) do
                ngx.say(ans.name, " ", ans.address or ans.cname,
                        " type:", ans.type, " class:", ans.class,
                        " ttl:", ans.ttl)
            end
        }
    }

    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   /usr/local/openresty/nginx/html;
    }

}

          

establish openresty Containers

docker run -it -d --net fixed --ip 172.18.0.2 -p 9000:80 \
-v /Users/huli/lua/openresty/dns/default.conf:/etc/nginx/conf.d/default.conf \
--name open-dns lihu12344/openresty

            

Use tests

[email protected] dns % curl localhost:9000/test
 Analysis results  ==> [{"ttl":204,"type":1,"section":1,"address":"104.244.46.85","name":"www.google.com","class":1}]
www.google.com 104.244.46.85 type:1 class:1 ttl:204

 Analysis results  ==> [{"ttl":752,"type":5,"section":1,"cname":"www.a.shifen.com","name":"www.baidu.com","class":1},{"ttl":11,"type":5,"section":1,"cname":"www.wshifen.com","name":"www.a.shifen.com","class":1},{"ttl":200,"type":1,"section":1,"address":"103.235.46.40","name":"www.wshifen.com","class":1}]
www.baidu.com www.a.shifen.com type:5 class:1 ttl:752
www.a.shifen.com www.wshifen.com type:5 class:1 ttl:11
www.wshifen.com 103.235.46.40 type:1 class:1 ttl:200

 Analysis results  ==> [{"ttl":600,"type":5,"section":1,"cname":"www.taobao.com.danuoyi.tbcache.com","name":"www.taobao.com","class":1}]
www.taobao.com www.taobao.com.danuoyi.tbcache.com type:5 class:1 ttl:600