├── LICENSE ├── README.md ├── dns.go ├── go.mod ├── go.sum ├── http.go ├── main.go └── proxy.go /LICENSE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. Definitions. 8 | 9 | "License" shall mean the terms and conditions for use, reproduction, 10 | and distribution as defined by Sections 1 through 9 of this document. 11 | 12 | "Licensor" shall mean the copyright owner or entity authorized by 13 | the copyright owner that is granting the License. 14 | 15 | "Legal Entity" shall mean the union of the acting entity and all 16 | other entities that control, are controlled by, or are under common 17 | control with that entity. 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We also recommend that a 185 | file or class name and description of purpose be included on the 186 | same "printed page" as the copyright notice for easier 187 | identification within third-party archives. 188 | 189 | Copyright [yyyy] [name of copyright owner] 190 | 191 | Licensed under the Apache License, Version 2.0 (the "License"); 192 | you may not use this file except in compliance with the License. 193 | You may obtain a copy of the License at 194 | 195 | http://www.apache.org/licenses/LICENSE-2.0 196 | 197 | Unless required by applicable law or agreed to in writing, software 198 | distributed under the License is distributed on an "AS IS" BASIS, 199 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 200 | See the License for the specific language governing permissions and 201 | limitations under the License. 202 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # Twitoderm CQ 2 | 3 | Some of the best minds of 50 years ago spent their time putting people on the moon. 4 | We arguably have even more "great minds" now working on getting people to look at ads. 5 | Specifically, huge firehoses of money are spent to addict people to their feeds and 6 | smart phones. People (including me!) spend countless hours scrolling through statuses 7 | and updates, all for the sake of interspersed advertisements. 8 | 9 | The "great minds" of our time are very good at hooking me, anyway, and driving 10 | the brain chemicals so that I can't put my phone down. 11 | 12 | I can't just ban Twitter and Reddit though. I need them for work. 13 | 14 | Twitoderm CQ seeks to put an end to social media feed addiction by making 15 | specifically addicting sites frustrating to load. 16 | 17 | ## How it works 18 | 19 | Twitoderm CQ is a DNS and TCP proxy. Users point their DNS client configuration 20 | at a running Twitoderm server, and Twitoderm just proxies through all DNS requests, 21 | unless the domain name is one of the configured bad sites. A configured bad site 22 | is returned an A record with TTL 5 that points back to Twitoderm. 23 | 24 | Twitoderm then uses TLS SNI and HTTP/1.1 Host headers to proxy the TCP traffic 25 | to and from the real destination, but much slower and with connection delays. 26 | 27 | Ideally, this is enough frustration to break my dopamine loop. 28 | 29 | ### Update 30 | 31 | My DNS forwarder has some pretty significant bugs. I'm currently using 32 | [dnsmasq](http://www.thekelleys.org.uk/dnsmasq/doc.html) 33 | for DNS, but am otherwise using Twitoderm unmodified. If someone wants 34 | to fix my DNS forwarding I would be delighted. 35 | 36 | ## Licence 37 | 38 | Copyright (C) 2019, JT Olio 39 | Licensed under Apache v2. See LICENSE for more info 40 | -------------------------------------------------------------------------------- /dns.go: -------------------------------------------------------------------------------- 1 | package main 2 | 3 | import ( 4 | "context" 5 | "fmt" 6 | "net" 7 | "strings" 8 | "sync" 9 | 10 | "golang.org/x/net/dns/dnsmessage" 11 | ) 12 | 13 | const ( 14 | TTL = 5 15 | ) 16 | 17 | type request struct { 18 | addr *net.UDPAddr 19 | id uint16 20 | } 21 | 22 | type DNSServer struct { 23 | upstream net.IP 24 | conn *net.UDPConn 25 | proxyResponse *dnsmessage.AResource 26 | toFilter []string 27 | 28 | mtx sync.Mutex 29 | idCounter uint16 30 | requests map[uint16]request 31 | } 32 | 33 | func NewDNS(upstreamIP, proxyIP string, dnsPort int, toFilter []string) (*DNSServer, error) { 34 | upstream := net.ParseIP(upstreamIP) 35 | if upstream == nil { 36 | return nil, fmt.Errorf("invalid upstream dns server: %q", upstreamIP) 37 | } 38 | 39 | proxy := net.ParseIP(proxyIP) 40 | if proxy == nil { 41 | return nil, fmt.Errorf("invalid proxy server: %q", proxyIP) 42 | } 43 | proxy = proxy.To4() 44 | if proxy == nil { 45 | return nil, fmt.Errorf("invalid proxy server: %q", proxyIP) 46 | } 47 | 48 | var arecord dnsmessage.AResource 49 | if copy(arecord.A[:], proxy) != 4 { 50 | return nil, fmt.Errorf("failed writing proxy body") 51 | } 52 | 53 | conn, err := net.ListenUDP("udp", &net.UDPAddr{Port: dnsPort}) 54 | if err != nil { 55 | return nil, err 56 | } 57 | return &DNSServer{ 58 | upstream: upstream, 59 | conn: conn, 60 | proxyResponse: &arecord, 61 | toFilter: toFilter, 62 | requests: map[uint16]request{}}, nil 63 | } 64 | 65 | func (s *DNSServer) Addr() net.Addr { 66 | return s.conn.LocalAddr() 67 | } 68 | 69 | func (s *DNSServer) Close() error { 70 | return s.conn.Close() 71 | } 72 | 73 | func (s *DNSServer) Run(ctx context.Context) error { 74 | var buf [4096]byte 75 | for { 76 | n, addr, err := s.conn.ReadFromUDP(buf[:]) 77 | if err != nil { 78 | // TODO: temporary errors 79 | return err 80 | } 81 | var msg dnsmessage.Message 82 | err = msg.Unpack(buf[:n]) 83 | if err != nil { 84 | fmt.Println("invalid dns packet: %v", err) 85 | continue 86 | } 87 | 88 | go func() { 89 | err := s.route(ctx, addr, &msg) 90 | if err != nil { 91 | fmt.Println("error: %v", err) 92 | } 93 | }() 94 | } 95 | 96 | return nil 97 | } 98 | 99 | func (s *DNSServer) route(ctx context.Context, source *net.UDPAddr, 100 | msg *dnsmessage.Message) error { 101 | if msg.Response { 102 | return s.proxy(ctx, source, msg) 103 | } 104 | return s.query(ctx, source, msg) 105 | } 106 | 107 | func (s *DNSServer) query(ctx context.Context, source *net.UDPAddr, 108 | msg *dnsmessage.Message) error { 109 | 110 | { 111 | s.mtx.Lock() 112 | 113 | r := request{ 114 | addr: source, 115 | id: msg.ID, 116 | } 117 | 118 | for { 119 | if _, exists := s.requests[s.idCounter]; !exists { 120 | break 121 | } 122 | s.idCounter += 1 123 | } 124 | msg.ID = s.idCounter 125 | s.idCounter += 1 126 | 127 | s.requests[msg.ID] = r 128 | 129 | s.mtx.Unlock() 130 | } 131 | 132 | packed, err := msg.Pack() 133 | if err != nil { 134 | return err 135 | } 136 | 137 | _, err = s.conn.WriteToUDP(packed, &net.UDPAddr{IP: s.upstream, Port: 53}) 138 | return err 139 | } 140 | 141 | func (s *DNSServer) proxy(ctx context.Context, source *net.UDPAddr, 142 | msg *dnsmessage.Message) error { 143 | 144 | s.mtx.Lock() 145 | r, exists := s.requests[msg.ID] 146 | if !exists { 147 | s.mtx.Unlock() 148 | return nil 149 | } 150 | 151 | delete(s.requests, msg.ID) 152 | s.mtx.Unlock() 153 | 154 | msg.ID = r.id 155 | 156 | for i, ans := range msg.Answers { 157 | if ans.Header.Class != dnsmessage.ClassINET { 158 | continue 159 | } 160 | switch ans.Header.Type { 161 | default: 162 | continue 163 | case dnsmessage.TypeA, dnsmessage.TypeAAAA, dnsmessage.TypeCNAME: 164 | } 165 | name := ans.Header.Name.String() 166 | for _, suffix := range s.toFilter { 167 | if strings.HasSuffix(name, suffix) { 168 | msg.Answers[i].Header.TTL = TTL 169 | msg.Answers[i].Body = s.proxyResponse 170 | break 171 | } 172 | } 173 | } 174 | 175 | packed, err := msg.Pack() 176 | if err != nil { 177 | return err 178 | } 179 | 180 | _, err = s.conn.WriteToUDP(packed, r.addr) 181 | return err 182 | } 183 | -------------------------------------------------------------------------------- /go.mod: -------------------------------------------------------------------------------- 1 | module github.com/jtolds/twitoderm 2 | 3 | go 1.13 4 | 5 | require ( 6 | github.com/juju/ratelimit v1.0.1 7 | github.com/spacemonkeygo/tlshowdy v0.0.0-20160207005338-8fa2cec1d7cd 8 | golang.org/x/net v0.0.0-20190912160710-24e19bdeb0f2 9 | ) 10 | -------------------------------------------------------------------------------- /go.sum: -------------------------------------------------------------------------------- 1 | github.com/juju/ratelimit v1.0.1 h1:+7AIFJVQ0EQgq/K9+0Krm7m530Du7tIz0METWzN0RgY= 2 | github.com/juju/ratelimit v1.0.1/go.mod h1:qapgC/Gy+xNh9UxzV13HGGl/6UXNN+ct+vwSgWNm/qk= 3 | github.com/spacemonkeygo/tlshowdy v0.0.0-20160207005338-8fa2cec1d7cd h1:1DS6oRTNvEIlcFDVe4OU/LKlrkRB/wx85GHJthitXw0= 4 | github.com/spacemonkeygo/tlshowdy v0.0.0-20160207005338-8fa2cec1d7cd/go.mod h1:MF7JYJoS2y353JlawNbpcLA0HAh4FzC4G+XrSIRP78c= 5 | golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w= 6 | golang.org/x/net v0.0.0-20190912160710-24e19bdeb0f2 h1:4dVFTC832rPn4pomLSz1vA+are2+dU19w1H8OngV7nc= 7 | golang.org/x/net v0.0.0-20190912160710-24e19bdeb0f2/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s= 8 | golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY= 9 | golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ= 10 | -------------------------------------------------------------------------------- /http.go: -------------------------------------------------------------------------------- 1 | package main 2 | 3 | import ( 4 | "bufio" 5 | "io" 6 | "regexp" 7 | ) 8 | 9 | var ( 10 | hostRegex = regexp.MustCompile(`^Host:\s+(.*?)$`) 11 | ) 12 | 13 | func httpHost(r io.Reader) (string, error) { 14 | scanner := bufio.NewScanner(r) 15 | for scanner.Scan() { 16 | text := scanner.Text() 17 | if text == "" { 18 | return "", nil 19 | } 20 | host := hostRegex.FindStringSubmatch(text) 21 | if len(host) > 1 { 22 | return host[1], nil 23 | } 24 | } 25 | return "", scanner.Err() 26 | } 27 | -------------------------------------------------------------------------------- /main.go: -------------------------------------------------------------------------------- 1 | package main 2 | 3 | import ( 4 | "context" 5 | "flag" 6 | "fmt" 7 | "strings" 8 | "time" 9 | ) 10 | 11 | var ( 12 | flagAddrs = flag.String("addrs", ":80,:443,:8080,:8081,:8443,:8888", 13 | "comma-separated list of addresses to listen on") 14 | flagUpstreamDNS = flag.String("upstream-dns", "8.8.8.8", 15 | "address of upstream resolver") 16 | flagProxyIP = flag.String("proxy-ip", "127.0.0.1", "address of proxier") 17 | flagSpeed = flag.Int("speed", 12*1024, 18 | "bytes per sec to allow in a single direction") 19 | flagConnDelay = flag.Duration("conn_delay", 5*time.Second, "connection delay") 20 | flagFilter = flag.String("filter", "twitter.com,twimg.com", 21 | "comma-separated list of domains to filter") 22 | flagDNSPort = flag.Int("dns-port", 53, "dns port to listen on") 23 | ) 24 | 25 | func main() { 26 | ctx := context.Background() 27 | flag.Parse() 28 | 29 | domains := strings.Split(*flagFilter, ",") 30 | for i, domain := range domains { 31 | if !strings.HasSuffix(domain, ".") { 32 | domains[i] += "." 33 | } 34 | } 35 | 36 | dns, err := NewDNS(*flagUpstreamDNS, *flagProxyIP, *flagDNSPort, domains) 37 | if err != nil { 38 | panic(err) 39 | } 40 | defer dns.Close() 41 | fmt.Printf("listening on %q\n", dns.Addr().String()) 42 | 43 | addrs := strings.Split(*flagAddrs, ",") 44 | errs := make(chan error, len(addrs)+1) 45 | for _, addr := range addrs { 46 | go func(addr string) { 47 | errs <- NewProxier(addr, *flagProxyIP, *flagSpeed, *flagConnDelay).Run(ctx) 48 | }(addr) 49 | } 50 | go func() { 51 | errs <- dns.Run(ctx) 52 | }() 53 | panic(<-errs) 54 | } 55 | -------------------------------------------------------------------------------- /proxy.go: -------------------------------------------------------------------------------- 1 | package main 2 | 3 | import ( 4 | "bytes" 5 | "context" 6 | "fmt" 7 | "io" 8 | "net" 9 | "strings" 10 | "sync" 11 | "time" 12 | 13 | "github.com/juju/ratelimit" 14 | "github.com/spacemonkeygo/tlshowdy" 15 | ) 16 | 17 | type Proxier struct { 18 | addr string 19 | bytesPerSec int 20 | connDelay time.Duration 21 | publicHost string 22 | 23 | mtx sync.Mutex 24 | buckets map[string]*ratelimit.Bucket 25 | } 26 | 27 | func NewProxier(addr, publicHost string, bytesPerSec int, connDelay time.Duration) *Proxier { 28 | return &Proxier{ 29 | addr: addr, 30 | bytesPerSec: bytesPerSec, 31 | connDelay: connDelay, 32 | publicHost: publicHost, 33 | buckets: map[string]*ratelimit.Bucket{}} 34 | } 35 | 36 | func (p *Proxier) slowDown(host string, r io.Reader) io.Reader { 37 | parts := strings.Split(host, ".") 38 | if len(parts) > 2 { 39 | parts = parts[len(parts)-2:] 40 | } 41 | host = strings.Join(parts, ".") 42 | 43 | p.mtx.Lock() 44 | defer p.mtx.Unlock() 45 | 46 | bucket, exists := p.buckets[host] 47 | if !exists { 48 | bucket = ratelimit.NewBucketWithRate(float64(p.bytesPerSec), int64(p.bytesPerSec)) 49 | p.buckets[host] = bucket 50 | } 51 | 52 | return ratelimit.Reader(r, bucket) 53 | } 54 | 55 | func (p *Proxier) proxyConn(ctx context.Context, host string, conn net.Conn) error { 56 | if strings.TrimSpace(host) == "" || host == p.publicHost { 57 | return fmt.Errorf("no host") 58 | } 59 | 60 | fmt.Println("+", host) 61 | defer fmt.Println("-", host) 62 | 63 | time.Sleep(p.connDelay) 64 | 65 | _, port, err := net.SplitHostPort(conn.LocalAddr().String()) 66 | if err != nil { 67 | return err 68 | } 69 | 70 | remote, err := (&net.Dialer{}).DialContext(ctx, "tcp", net.JoinHostPort(host, port)) 71 | if err != nil { 72 | return err 73 | } 74 | defer remote.Close() 75 | defer conn.Close() 76 | 77 | errs := make(chan error, 2) 78 | 79 | go func() { 80 | _, err := io.Copy(remote, p.slowDown(host, conn)) 81 | errs <- err 82 | }() 83 | 84 | go func() { 85 | _, err := io.Copy(conn, p.slowDown(host, remote)) 86 | errs <- err 87 | }() 88 | 89 | <-errs 90 | return nil 91 | } 92 | 93 | func (p *Proxier) handleConn(ctx context.Context, conn net.Conn) error { 94 | recorder := tlshowdy.NewRecordingReader(conn) 95 | hello, err := tlshowdy.Read(recorder) 96 | if err != nil { 97 | return err 98 | } 99 | if hello != nil { 100 | return p.proxyConn(ctx, hello.ServerName, tlshowdy.NewPrefixConn(recorder.Received, conn)) 101 | } 102 | host, err := httpHost(io.MultiReader(bytes.NewReader(append([]byte(nil), recorder.Received...)), recorder)) 103 | if err != nil { 104 | return err 105 | } 106 | return p.proxyConn(ctx, host, tlshowdy.NewPrefixConn(recorder.Received, conn)) 107 | } 108 | 109 | func (p *Proxier) Run(ctx context.Context) error { 110 | l, err := (&net.ListenConfig{}).Listen(ctx, "tcp", p.addr) 111 | if err != nil { 112 | return err 113 | } 114 | defer l.Close() 115 | 116 | fmt.Printf("listening on %q\n", l.Addr().String()) 117 | 118 | for { 119 | conn, err := l.Accept() 120 | if err != nil { 121 | // TODO: backoff on temporary 122 | return err 123 | } 124 | go func() { 125 | defer conn.Close() 126 | err := p.handleConn(ctx, conn) 127 | if err != nil { 128 | fmt.Printf("failed handling conn: %v\n", err) 129 | } 130 | }() 131 | } 132 | 133 | return nil 134 | } 135 | --------------------------------------------------------------------------------