Merge remote-tracking branch 'origin/master' into stable

golangci-lint 1.42.1

.github/workflows/ci.yaml

@@ -2,6 +2,18 @@
 
 name: CI
 
+permissions:
+  actions: read
+  checks: read
+  contents: read
+  deployments: read
+  issues: read
+  discussions: read
+  pull-requests: read
+  repository-projects: read
+  security-events: read
+  statuses: read
+
 on:
   push:
     tags:
@@ -30,7 +42,8 @@ jobs:
     strategy:
       matrix:
         go_version:
-          - ^1.16
+          - ~1.16
+          - ^1.17
     steps:
       - name: Checkout
         uses: actions/checkout@v2
@@ -70,12 +83,12 @@ jobs:
       - name: Run linter
         uses: golangci/golangci-lint-action@v2
         with:
-          version: v1.41.1
+          version: v1.42.1
 
   docker:
     name: Docker
     runs-on: ubuntu-latest
-    timeout-minutes: 15
+    timeout-minutes: 20
     steps:
       - name: Checkout
         uses: actions/checkout@v2

.github/workflows/codeql-analysis.yml

@@ -11,6 +11,14 @@
 #
 name: "CodeQL"
 
+# https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#permissions
+# https://github.com/github/codeql-action/issues/572
+permissions:
+  actions: read
+  contents: read
+  pull-requests: read
+  security-events: write
+
 on:
   push:
     branches: 

Dockerfile

@@ -1,7 +1,7 @@
 ###############################################################################
 # BUILD STAGE
 
-FROM golang:1.16-alpine AS build
+FROM golang:1.17-alpine AS build
 
 RUN set -x \
   && apk --no-cache --update add \

Makefile

@@ -2,7 +2,7 @@ ROOT_DIR     := $(shell dirname $(realpath $(lastword $(MAKEFILE_LIST))))
 IMAGE_NAME   := mtg
 APP_NAME     := $(IMAGE_NAME)
 
-GOLANGCI_LINT_VERSION := v1.41.1
+GOLANGCI_LINT_VERSION := v1.42.1
 
 VERSION_GO         := $(shell go version)
 VERSION_DATE       := $(shell date -Ru)
@@ -83,15 +83,15 @@ install-tools-lint: .bin
 
 .PHONY: install-tools-godoc
 install-tools-godoc: .bin
-	@$(GOTOOL) go get -u golang.org/x/tools/cmd/godoc
+	@$(GOTOOL) go install golang.org/x/tools/cmd/godoc@latest
 
 .PHONY: install-tools-gofumpt
 install-tools-gofumpt: .bin
-	@$(GOTOOL) go get -u mvdan.cc/gofumpt
+	@$(GOTOOL) go install mvdan.cc/gofumpt@latest
 
 .PHONY: goreleaser
 install-tools-goreleaser: .bin
-	@$(GOTOOL) go get -u github.com/goreleaser/goreleaser
+	@$(GOTOOL) go install github.com/goreleaser/goreleaser@latest
 
 .PHONY: update-deps
 update-deps:

example.config.toml

@@ -56,6 +56,19 @@ domain-fronting-port = 443
 # time range of this parameter.
 tolerate-time-skewness = "5s"
 
+# Telegram has a concept of DC. You can think about DC as a number of a cluster
+# with a certain purpose. Some clusters serve media, some - messages, some rule
+# channels and so on. But sometimes unknown DC number is requested by client.
+# It could be a bug or some global reconfiguration of the Telegram.
+#
+# By default, proxy rejects such requests. But it is also possible to fallback
+# this request to any DC. Telegram works in a way that any DC is able to serve
+# any request but sacrificing a latency.
+#
+# If this setting is disabled (default), mtg will reject a connection.
+# Otherwise, chose a new DC.
+allow-fallback-on-unknown-dc = false
+
 # network defines different network-related settings
 [network]
 # please be aware that mtg needs to do some external requests. For

go.mod

@@ -1,32 +1,50 @@
 module github.com/9seconds/mtg/v2
 
-go 1.16
+go 1.17
 
 require (
 	github.com/OneOfOne/xxhash v1.2.8
 	github.com/alecthomas/kong v0.2.17
-	github.com/alecthomas/units v0.0.0-20210208195552-ff826a37aa15
+	github.com/alecthomas/units v0.0.0-20210927113745-59d0afb8317a
 	github.com/armon/go-socks5 v0.0.0-20160902184237-e75332964ef5
 	github.com/babolivier/go-doh-client v0.0.0-20201028162107-a76cff4cb8b6
 	github.com/d4l3k/messagediff v1.2.1 // indirect
 	github.com/golang/protobuf v1.5.2 // indirect
 	github.com/gotd/td v0.34.0
 	github.com/jarcoal/httpmock v1.0.8
-	github.com/kentik/patricia v0.0.0-20201202224819-f9447a6e25f1
+	github.com/kentik/patricia v0.0.0-20210909164817-21603333b70e
-	github.com/libp2p/go-reuseport v0.0.2
 	github.com/mccutchen/go-httpbin v1.1.1
 	github.com/panjf2000/ants/v2 v2.4.6
-	github.com/pelletier/go-toml v1.9.3
+	github.com/pelletier/go-toml v1.9.4
 	github.com/prometheus/client_golang v1.11.0
-	github.com/prometheus/common v0.30.0 // indirect
+	github.com/prometheus/common v0.31.1 // indirect
-	github.com/prometheus/procfs v0.7.1 // indirect
+	github.com/prometheus/procfs v0.7.3 // indirect
-	github.com/rs/zerolog v1.23.0
+	github.com/rs/zerolog v1.25.0
 	github.com/smira/go-statsd v1.3.2
 	github.com/stretchr/objx v0.3.0 // indirect
 	github.com/stretchr/testify v1.7.0
 	github.com/tylertreat/BoomFilters v0.0.0-20210315201527-1a82519a3e43
-	golang.org/x/crypto v0.0.0-20210711020723-a769d52b0f97
+	golang.org/x/crypto v0.0.0-20210921155107-089bfa567519
-	golang.org/x/net v0.0.0-20210726213435-c6fcb2dbf985
+	golang.org/x/net v0.0.0-20211005001312-d4b1ae081e3b
-	golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c
+	golang.org/x/sys v0.0.0-20211004093028-2c5d950f24ef
 	google.golang.org/protobuf v1.27.1 // indirect
 )
+
+require (
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cenkalti/backoff/v4 v4.1.0 // indirect
+	github.com/cespare/xxhash/v2 v2.1.2 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/gotd/ige v0.1.5 // indirect
+	github.com/gotd/xor v0.1.1 // indirect
+	github.com/matttproud/golang_protobuf_extensions v1.0.1 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/prometheus/client_model v0.2.0 // indirect
+	go.uber.org/atomic v1.7.0 // indirect
+	go.uber.org/multierr v1.6.0 // indirect
+	go.uber.org/zap v1.16.0 // indirect
+	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c // indirect
+	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect
+	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
+)

go.sum

@@ -44,8 +44,8 @@ github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751/go.mod h1:LOuy
 github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
 github.com/alecthomas/units v0.0.0-20190717042225-c3de453c63f4/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
 github.com/alecthomas/units v0.0.0-20190924025748-f65c72e2690d/go.mod h1:rBZYJk541a8SKzHPHnH3zbiI+7dagKZ0cgpgrD7Fyho=
-github.com/alecthomas/units v0.0.0-20210208195552-ff826a37aa15 h1:AUNCr9CiJuwrRYS3XieqF+Z9B9gNxo/eANAJCF2eiN4=
+github.com/alecthomas/units v0.0.0-20210927113745-59d0afb8317a h1:E/8AP5dFtMhl5KPJz66Kt9G0n+7Sn41Fy1wv9/jHOrc=
-github.com/alecthomas/units v0.0.0-20210208195552-ff826a37aa15/go.mod h1:OMCwj8VM1Kc9e19TLln2VL61YJF0x1XFtfdL4JdbSyE=
+github.com/alecthomas/units v0.0.0-20210927113745-59d0afb8317a/go.mod h1:OMCwj8VM1Kc9e19TLln2VL61YJF0x1XFtfdL4JdbSyE=
 github.com/andres-erbsen/clock v0.0.0-20160526145045-9e14626cd129/go.mod h1:rFgpPQZYZ8vdbc+48xibu8ALc3yeyd64IhHS+PU6Yyg=
 github.com/andybalholm/cascadia v1.1.0/go.mod h1:GsXiBklL0woXo1j/WYWtSYYC4ouU9PqHO0sqidkEA4Y=
 github.com/armon/go-socks5 v0.0.0-20160902184237-e75332964ef5 h1:0CwZNZbxp69SHPdPJAN/hZIm0C4OItdklCFmMRWYpio=
@@ -59,8 +59,9 @@ github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6r
 github.com/cenkalti/backoff/v4 v4.1.0 h1:c8LkOFQTzuO0WBM/ae5HdGQuZPfPxp7lqBRwQRm4fSc=
 github.com/cenkalti/backoff/v4 v4.1.0/go.mod h1:scbssz8iZGpm3xbr14ovlUdkxfGXNInqkPWOWmG2CLw=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
-github.com/cespare/xxhash/v2 v2.1.1 h1:6MnRN8NT7+YBpUIWxHtefFZOKTAPgGjpQSxqLNn0+qY=
 github.com/cespare/xxhash/v2 v2.1.1/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
+github.com/cespare/xxhash/v2 v2.1.2 h1:YRXhKfTDauu4ajMg1TPgFO5jnlC2HCbmLXMcTG5cbYE=
+github.com/cespare/xxhash/v2 v2.1.2/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/chzyer/logex v1.1.10/go.mod h1:+Ywpsq7O8HXn0nuIou7OrIPyXbp3wmkHB+jjWRnGsAI=
 github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e/go.mod h1:nSuG5e5PlCu98SY8svDHJxuZscDgtXS6KTTbou5AhLI=
 github.com/chzyer/test v0.0.0-20180213035817-a1ea475d72b1/go.mod h1:Q3SI9o4m/ZMnBNeIyt5eFwwo7qiLfzFZmjNmxjkiQlU=
@@ -168,8 +169,8 @@ github.com/julienschmidt/httprouter v1.2.0/go.mod h1:SYymIcj16QtmaHHD7aYtjjsJG7V
 github.com/julienschmidt/httprouter v1.3.0/go.mod h1:JR6WtHb+2LUe8TCKY3cZOxFyyO8IZAc4RVcycCCAKdM=
 github.com/k0kubun/colorstring v0.0.0-20150214042306-9440f1994b88/go.mod h1:3w7q1U84EfirKl04SVQ/s7nPm1ZPhiXd34z40TNz36k=
 github.com/k0kubun/pp v2.4.0+incompatible/go.mod h1:GWse8YhT0p8pT4ir3ZgBbfZild3tgzSScAn6HmfYukg=
-github.com/kentik/patricia v0.0.0-20201202224819-f9447a6e25f1 h1:D7qhJP3R49ZjUzpzKQ6B2H3lgejPs6DTO5gRomhhOpE=
+github.com/kentik/patricia v0.0.0-20210909164817-21603333b70e h1:1wAVuGu1c+lsdaOPQN+9xoP9+gaIMJV6H0ehGc+K5iA=
-github.com/kentik/patricia v0.0.0-20201202224819-f9447a6e25f1/go.mod h1:2OfLA+0esiUJpwMjrH39pEk79cb8MvGTBS9YlZpejJ4=
+github.com/kentik/patricia v0.0.0-20210909164817-21603333b70e/go.mod h1:2OfLA+0esiUJpwMjrH39pEk79cb8MvGTBS9YlZpejJ4=
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
 github.com/konsorten/go-windows-terminal-sequences v1.0.1/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
 github.com/konsorten/go-windows-terminal-sequences v1.0.3/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
@@ -179,8 +180,6 @@ github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORN
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
-github.com/libp2p/go-reuseport v0.0.2 h1:XSG94b1FJfGA01BUrT82imejHQyTxO4jEWqheyCXYvU=
-github.com/libp2p/go-reuseport v0.0.2/go.mod h1:SPD+5RwGC7rcnzngoYC86GjPzjSywuQyMVAheVBD9nQ=
 github.com/mattn/go-colorable v0.1.2/go.mod h1:U0ppj6V5qS13XJ6of8GYAs25YV2eR4EVcfRqFIhoBtE=
 github.com/mattn/go-isatty v0.0.8/go.mod h1:Iq45c/XA43vh69/j3iqttzPXn0bhXyGjM0Hdxcsrc5s=
 github.com/mattn/go-isatty v0.0.9/go.mod h1:YNRxwqDuOph6SZLI9vUUz6OYw3QyUt7WiY2yME+cCiQ=
@@ -196,8 +195,8 @@ github.com/mwitkow/go-conntrack v0.0.0-20161129095857-cc309e4a2223/go.mod h1:qRW
 github.com/mwitkow/go-conntrack v0.0.0-20190716064945-2f068394615f/go.mod h1:qRWi+5nqEBWmkhHvq77mSJWrCKwh8bxhgT7d/eI7P4U=
 github.com/panjf2000/ants/v2 v2.4.6 h1:drmj9mcygn2gawZ155dRbo+NfXEfAssjZNU1qoIb4gQ=
 github.com/panjf2000/ants/v2 v2.4.6/go.mod h1:f6F0NZVFsGCp5A7QW/Zj/m92atWwOkY0OIhFxRNFr4A=
-github.com/pelletier/go-toml v1.9.3 h1:zeC5b1GviRUyKYd6OJPvBU/mcVDVoL1OhT17FCt5dSQ=
+github.com/pelletier/go-toml v1.9.4 h1:tjENF6MfZAg8e4ZmZTeWaWiT2vXtsoO6+iuOjFhECwM=
-github.com/pelletier/go-toml v1.9.3/go.mod h1:u1nR/EPcESfeI/szUZKdtJ0xRNbUoANCkoOuaOx1Y+c=
+github.com/pelletier/go-toml v1.9.4/go.mod h1:u1nR/EPcESfeI/szUZKdtJ0xRNbUoANCkoOuaOx1Y+c=
 github.com/pkg/diff v0.0.0-20210226163009-20ebb0f2a09e/go.mod h1:pJLUxLENpZxwdsKMEsNbx1VGcRFpLqf3715MtcvvzbA=
 github.com/pkg/errors v0.8.0/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
@@ -218,20 +217,20 @@ github.com/prometheus/client_model v0.2.0/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6T
 github.com/prometheus/common v0.4.1/go.mod h1:TNfzLD0ON7rHzMJeJkieUDPYmFC7Snx/y86RQel1bk4=
 github.com/prometheus/common v0.10.0/go.mod h1:Tlit/dnDKsSWFlCLTWaA1cyBgKHSMdTB80sz/V91rCo=
 github.com/prometheus/common v0.26.0/go.mod h1:M7rCNAaPfAosfx8veZJCuw84e35h3Cfd9VFqTh1DIvc=
-github.com/prometheus/common v0.30.0 h1:JEkYlQnpzrzQFxi6gnukFPdQ+ac82oRhzMcIduJu/Ug=
+github.com/prometheus/common v0.31.1 h1:d18hG4PkHnNAKNMOmFuXFaiY8Us0nird/2m60uS1AMs=
-github.com/prometheus/common v0.30.0/go.mod h1:vu+V0TpY+O6vW9J44gczi3Ap/oXXR10b+M/gUGO4Hls=
+github.com/prometheus/common v0.31.1/go.mod h1:vu+V0TpY+O6vW9J44gczi3Ap/oXXR10b+M/gUGO4Hls=
 github.com/prometheus/procfs v0.0.0-20181005140218-185b4288413d/go.mod h1:c3At6R/oaqEKCNdg8wHV1ftS6bRYblBhIjjI8uT2IGk=
 github.com/prometheus/procfs v0.0.2/go.mod h1:TjEm7ze935MbeOT/UhFTIMYKhuLP4wbCsTZCD3I8kEA=
 github.com/prometheus/procfs v0.1.3/go.mod h1:lV6e/gmhEcM9IjHGsFOCxxuZ+z1YqCvr4OA4YeYWdaU=
 github.com/prometheus/procfs v0.6.0/go.mod h1:cz+aTbrPOrUb4q7XlbU9ygM+/jj0fzG6c1xBZuNvfVA=
-github.com/prometheus/procfs v0.7.1 h1:TlEtJq5GvGqMykEwWzbZWjjztF86swFhsPix1i0bkgA=
+github.com/prometheus/procfs v0.7.3 h1:4jVXhlkAyzOScmCkXBTOLRLTz8EeU+eyjrwB/EPq0VU=
-github.com/prometheus/procfs v0.7.1/go.mod h1:cz+aTbrPOrUb4q7XlbU9ygM+/jj0fzG6c1xBZuNvfVA=
+github.com/prometheus/procfs v0.7.3/go.mod h1:cz+aTbrPOrUb4q7XlbU9ygM+/jj0fzG6c1xBZuNvfVA=
 github.com/quasilyte/go-ruleguard/dsl v0.3.2/go.mod h1:KeCP03KrjuSO0H1kTuZQCWlQPulDV6YMIXmpQss17rU=
 github.com/rogpeppe/go-internal v1.3.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=
 github.com/rogpeppe/go-internal v1.8.0/go.mod h1:WmiCO8CzOY8rg0OYDC4/i/2WRWAB6poM+XZ2dLUbcbE=
-github.com/rs/xid v1.2.1/go.mod h1:+uKXf+4Djp6Md1KODXJxgGQPKngRmWyn10oCKFzNHOQ=
+github.com/rs/xid v1.3.0/go.mod h1:trrq9SKmegXys3aeAKXMUTdJsYXVwGY3RLcfgqegfbg=
-github.com/rs/zerolog v1.23.0 h1:UskrK+saS9P9Y789yNNulYKdARjPZuS35B8gJF2x60g=
+github.com/rs/zerolog v1.25.0 h1:Rj7XygbUHKUlDPcVdoLyR91fJBsduXj5fRxyqIQj/II=
-github.com/rs/zerolog v1.23.0/go.mod h1:6c7hFfxPOy7TacJc4Fcdi24/J0NKYGzjG8FWRI916Qo=
+github.com/rs/zerolog v1.25.0/go.mod h1:7KHcEGe0QZPOm2IE4Kpb5rTh6n1h2hIgS5OOnu1rUaI=
 github.com/sebdah/goldie/v2 v2.5.3/go.mod h1:oZ9fp0+se1eapSRjfYbsV/0Hqhbuu3bJVvKI/NNtssI=
 github.com/sergi/go-diff v1.0.0/go.mod h1:0CfEIISq7TuYL3j771MWULgwwjU+GofnZX9QAmXWZgo=
 github.com/sergi/go-diff v1.1.0/go.mod h1:STckp+ISIX8hZLjrqAeVduY0gWCT9IjLuqbuNXdaHfM=
@@ -248,7 +247,6 @@ github.com/stretchr/testify v1.1.5-0.20170809224252-890a5c3458b4/go.mod h1:a8OnR
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
-github.com/stretchr/testify v1.5.1/go.mod h1:5W2xD1RspED5o8YsWQXVCued0rvSQ+mT+I5cxcmMvtA=
 github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
@@ -257,7 +255,7 @@ github.com/tylertreat/BoomFilters v0.0.0-20210315201527-1a82519a3e43/go.mod h1:O
 github.com/yuin/goldmark v1.1.25/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.1.27/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.1.32/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
-github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
+github.com/yuin/goldmark v1.3.5/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
 go.opencensus.io v0.21.0/go.mod h1:mSImk1erAIZhrmZN+AvHh14ztQfjbGwt4TtuofqLduU=
 go.opencensus.io v0.22.0/go.mod h1:+kGneAE2xo2IficOXnaByMWTGM9T73dGwxeWcUqIpI8=
 go.opencensus.io v0.22.2/go.mod h1:yxeiOL68Rb0Xd1ddK5vPZ/oVn4vY4Ynel7k9FzqtOIw=
@@ -279,8 +277,8 @@ golang.org/x/crypto v0.0.0-20190510104115-cbcb75029529/go.mod h1:yigFU9vqHzYiE8U
 golang.org/x/crypto v0.0.0-20190605123033-f99c8df09eb5/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
-golang.org/x/crypto v0.0.0-20210711020723-a769d52b0f97 h1:/UOmuWzQfxxo9UtlXMwuQU8CMgg1eZXqTRwkSQJWKOI=
+golang.org/x/crypto v0.0.0-20210921155107-089bfa567519 h1:7I4JAnoQBe7ZtJcBaYHi5UtiO8tQHbUSXxL+pnGRANg=
-golang.org/x/crypto v0.0.0-20210711020723-a769d52b0f97/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
+golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
 golang.org/x/exp v0.0.0-20190121172915-509febef88a4/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20190306152737-a1d7652674e8/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20190510132918-efd6b22b2522/go.mod h1:ZjyILWgesfNpC6sMxTJOJm9Kp84zZh5NQWvqDGG3Qr8=
@@ -311,8 +309,9 @@ golang.org/x/mod v0.1.0/go.mod h1:0QHyrYULN0/3qlju5TqG8bIK38QM8yzMo5ekMj3DlcY=
 golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee/go.mod h1:QqPTAvyqsEbceGzBzNggFXnrqF1CaUcvgkdR5Ot7KZg=
 golang.org/x/mod v0.1.1-0.20191107180719-034126e5016b/go.mod h1:QqPTAvyqsEbceGzBzNggFXnrqF1CaUcvgkdR5Ot7KZg=
 golang.org/x/mod v0.2.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
-golang.org/x/mod v0.3.0 h1:RM4zey1++hCTbCVQfnWeKs9/IEsaBLA8vTkd0WVtmH4=
 golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
+golang.org/x/mod v0.4.2 h1:Gz96sIWK3OalVv/I/qNygP42zyoKp3xptRVCWRFEBvo=
+golang.org/x/mod v0.4.2/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/net v0.0.0-20180218175443-cbe0f9307d01/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20180724234803-3673e40ba225/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20180826012351-8a410e7b638d/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
@@ -344,9 +343,10 @@ golang.org/x/net v0.0.0-20200707034311-ab3426394381/go.mod h1:/O7V0waA8r7cgGh81R
 golang.org/x/net v0.0.0-20200822124328-c89045814202/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
 golang.org/x/net v0.0.0-20201021035429-f5854403a974/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=
 golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
+golang.org/x/net v0.0.0-20210405180319-a5a99cb37ef4/go.mod h1:p54w0d4576C0XHj96bSt6lcn1PtDYWL6XObtHCRCNQM=
 golang.org/x/net v0.0.0-20210525063256-abc453219eb5/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
-golang.org/x/net v0.0.0-20210726213435-c6fcb2dbf985 h1:4CSI6oo7cOjJKajidEljs9h+uP0rRZBPPPhcCbj5mw8=
+golang.org/x/net v0.0.0-20211005001312-d4b1ae081e3b h1:SXy8Ld8oKlcogOvUAh0J5Pm5RKzgYBMMxLxt6n5XW50=
-golang.org/x/net v0.0.0-20210726213435-c6fcb2dbf985/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/net v0.0.0-20211005001312-d4b1ae081e3b/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
 golang.org/x/oauth2 v0.0.0-20190226205417-e64efc72b421/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
 golang.org/x/oauth2 v0.0.0-20190604053449-0f29369cfe45/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
@@ -361,15 +361,14 @@ golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJ
 golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20200317015054-43a5402ce75a/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20200625203802-6e8e738ad208/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sync v0.0.0-20201020160332-67f06af15bc9/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sync v0.0.0-20201207232520-09787c993a3a h1:DcqTD9SDLc+1P/r1EmRBwnVsrOwW+kk2vWf9n+1sGhs=
 golang.org/x/sync v0.0.0-20201207232520-09787c993a3a/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20210220032951-036812b2e83c h1:5KslGYwFpkhGh+Q16bwMP3cOontH8FOep7tGV86Y7SQ=
+golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20180830151530-49385e6e1522/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20180905080454-ebe1bf3edb33/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20181116152217-5ac8a444bdc5/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190222072716-a9d3bda3a223/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
-golang.org/x/sys v0.0.0-20190228124157-a34e9553db1e/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190312061237-fead79001313/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190422165155-953cdadca894/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
@@ -400,13 +399,14 @@ golang.org/x/sys v0.0.0-20200625212154-ddb9806d33ae/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20200803210538-64077c9b5642/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20210119212857-b64e53b001e4/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210124154548-22da62e12c0c/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210330210617-4fbd30eecc44/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210510120138-977fb7262007/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210603081109-ebe580a85c40/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c h1:F1jZWGFhYfh0Ci55sIpILtKKK8p3i2/krTr0H1rg74I=
+golang.org/x/sys v0.0.0-20211004093028-2c5d950f24ef h1:fPxZ3Umkct3LZ8gK9nbk+DWDJ9fstZa2grBn+lWVKPs=
-golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20211004093028-2c5d950f24ef/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
@@ -460,8 +460,8 @@ golang.org/x/tools v0.0.0-20200729194436-6467de6f59a7/go.mod h1:njjCfa9FT2d7l9Bc
 golang.org/x/tools v0.0.0-20200804011535-6c149bb5ef0d/go.mod h1:njjCfa9FT2d7l9Bc6FUM5FLjQPp3cFF28FI3qnDFljA=
 golang.org/x/tools v0.0.0-20200820010801-b793a1359eac/go.mod h1:njjCfa9FT2d7l9Bc6FUM5FLjQPp3cFF28FI3qnDFljA=
 golang.org/x/tools v0.0.0-20200825202427-b303f430e36d/go.mod h1:njjCfa9FT2d7l9Bc6FUM5FLjQPp3cFF28FI3qnDFljA=
-golang.org/x/tools v0.1.0 h1:po9/4sTYwZU9lPhi1tOrb4hCv3qrhiQ77LZfGa2OjwY=
+golang.org/x/tools v0.1.5 h1:ouewzE6p+/VEB31YYnTbEJdi8pFqKp4P4n85vwo3DHA=
-golang.org/x/tools v0.1.0/go.mod h1:xkSsbof2nBLbhDlRMhhhyNLN/zl3eTqcnHD5viDpcZ0=
+golang.org/x/tools v0.1.5/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

internal/cli/run_proxy.go

@@ -156,7 +156,7 @@ func makeEventStream(conf *config.Config, logger mtglib.Logger) (mtglib.EventStr
 func runProxy(conf *config.Config, version string) error {
 	logger := makeLogger(conf)
 
-	logger.BindStr("configuration", conf.String()).Debug("configuration")
+	logger.BindJSON("configuration", conf.String()).Debug("configuration")
 
 	ntw, err := makeNetwork(conf, version)
 	if err != nil {
@@ -183,8 +183,9 @@ func runProxy(conf *config.Config, version string) error {
 		Secret:             conf.Secret,
 		BufferSize:         conf.TCPBuffer.Get(mtglib.DefaultBufferSize),
 		DomainFrontingPort: conf.DomainFrontingPort.Get(mtglib.DefaultDomainFrontingPort),
-		IdleTimeout:        conf.Network.Timeout.Idle.Get(mtglib.DefaultIdleTimeout),
 		PreferIP:           conf.PreferIP.Get(mtglib.DefaultPreferIP),
+
+		AllowFallbackOnUnknownDC: conf.AllowFallbackOnUnknownDC.Get(false),
 	}
 
 	proxy, err := mtglib.NewProxy(opts)
@@ -192,7 +193,7 @@ func runProxy(conf *config.Config, version string) error {
 		return fmt.Errorf("cannot create a proxy: %w", err)
 	}
 
-	listener, err := net.Listen("tcp", conf.BindTo.Get(""))
+	listener, err := utils.NewListener(conf.BindTo.Get(""), int(opts.BufferSize))
 	if err != nil {
 		return fmt.Errorf("cannot start proxy: %w", err)
 	}

internal/cli/simple_run.go

@@ -71,6 +71,7 @@ func (s *SimpleRun) Run(cli *CLI, version string) error { // nolint: cyclop
 	}
 
 	conf.Debug.Value = s.Debug
+	conf.AllowFallbackOnUnknownDC.Value = true
 	conf.Defense.AntiReplay.Enabled.Value = true
 
 	if err := conf.Validate(); err != nil {

internal/config/config.go

@@ -10,6 +10,7 @@ import (
 
 type Config struct {
 	Debug                    TypeBool        `json:"debug"`
+	AllowFallbackOnUnknownDC TypeBool        `json:"allowFallbackOnUnknownDc"`
 	Secret                   mtglib.Secret   `json:"secret"`
 	BindTo                   TypeHostPort    `json:"bindTo"`
 	TCPBuffer                TypeBytes       `json:"tcpBuffer"`

internal/config/parse.go

@@ -10,6 +10,7 @@ import (
 
 type tomlConfig struct {
 	Debug                    bool   `toml:"debug" json:"debug,omitempty"`
+	AllowFallbackOnUnknownDC bool   `toml:"allow-fallback-on-unknown-dc" json:"allowFallbackOnUnknownDc,omitempty"`
 	Secret                   string `toml:"secret" json:"secret"`
 	BindTo                   string `toml:"bind-to" json:"bindTo"`
 	TCPBuffer                string `toml:"tcp-buffer" json:"tcpBuffer,omitempty"`

internal/utils/net_listener.go

@@ -0,0 +1,41 @@
+package utils
+
+import (
+	"fmt"
+	"net"
+
+	"github.com/9seconds/mtg/v2/network"
+)
+
+type Listener struct {
+	net.Listener
+
+	bufferSize int
+}
+
+func (l Listener) Accept() (net.Conn, error) {
+	conn, err := l.Listener.Accept()
+	if err != nil {
+		return nil, err // nolint: wrapcheck
+	}
+
+	if err := network.SetClientSocketOptions(conn, l.bufferSize); err != nil {
+		conn.Close()
+
+		return nil, fmt.Errorf("cannot set TCP options: %w", err)
+	}
+
+	return conn, nil
+}
+
+func NewListener(bindTo string, bufferSize int) (net.Listener, error) {
+	base, err := net.Listen("tcp", bindTo)
+	if err != nil {
+		return nil, fmt.Errorf("cannot build a base listener: %w", err)
+	}
+
+	return Listener{
+		Listener:   base,
+		bufferSize: bufferSize,
+	}, nil
+}

internal/utils/rlimit.go

@@ -1,3 +1,4 @@
+//go:build !windows
 // +build !windows
 
 package utils

internal/utils/rlimit_windows.go

@@ -1,3 +1,4 @@
+//go:build windows
 // +build windows
 
 package utils

internal/utils/root_context.go

@@ -1,3 +1,4 @@
+//go:build !windows
 // +build !windows
 
 package utils

internal/utils/root_context_windows.go

@@ -1,3 +1,4 @@
+//go:build windows
 // +build windows
 
 package utils

ipblocklist/firehol.go

@@ -121,7 +121,7 @@ func (f *Firehol) Run(updateEach time.Duration) {
 func (f *Firehol) containsIPv4(addr net.IP) bool {
 	ip := patricia.NewIPv4AddressFromBytes(addr, 32) // nolint: gomnd
 
-	if ok, _, err := f.treeV4.FindDeepestTag(ip); ok && err == nil {
+	if ok, _ := f.treeV4.FindDeepestTag(ip); ok {
 		return true
 	}
 
@@ -131,7 +131,7 @@ func (f *Firehol) containsIPv4(addr net.IP) bool {
 func (f *Firehol) containsIPv6(addr net.IP) bool {
 	ip := patricia.NewIPv6Address(addr, 128) // nolint: gomnd
 
-	if ok, _, err := f.treeV6.FindDeepestTag(ip); ok && err == nil {
+	if ok, _ := f.treeV6.FindDeepestTag(ip); ok {
 		return true
 	}
 
@@ -267,9 +267,7 @@ func (f *Firehol) updateTrees(mutex sync.Locker,
 			return fmt.Errorf("cannot parse a line: %w", err)
 		}
 
-		if err := f.updateAddToTrees(ip, cidr, mutex, v4tree, v6tree); err != nil {
+		f.updateAddToTrees(ip, cidr, mutex, v4tree, v6tree)
-			return fmt.Errorf("cannot add a node to the tree: %w", err)
-		}
 	}
 
 	if scanner.Err() != nil {
@@ -302,27 +300,17 @@ func (f *Firehol) updateParseLine(text string) (net.IP, uint, error) {
 
 func (f *Firehol) updateAddToTrees(ip net.IP, cidr uint,
 	mutex sync.Locker,
-	v4tree *bool_tree.TreeV4, v6tree *bool_tree.TreeV6) error {
+	v4tree *bool_tree.TreeV4, v6tree *bool_tree.TreeV6) {
 	mutex.Lock()
 	defer mutex.Unlock()
 
 	if ip.To4() != nil {
-		addr := patricia.NewIPv4AddressFromBytes(ip, cidr)
+		v4tree.Set(patricia.NewIPv4AddressFromBytes(ip, cidr), true)
-
-		if _, _, err := v4tree.Set(addr, true); err != nil {
-			return err // nolint: wrapcheck
-		}
 	} else {
-		addr := patricia.NewIPv6Address(ip, cidr)
+		v6tree.Set(patricia.NewIPv6Address(ip, cidr), true)
-
-		if _, _, err := v6tree.Set(addr, true); err != nil {
-			return err // nolint: wrapcheck
 	}
 }
 
-	return nil
-}
-
 // NewFirehol creates a new instance of FireHOL IP blocklist.
 //
 // This method does not start an update process so please execute Run

logger/noop.go

@@ -7,6 +7,7 @@ type noopLogger struct{}
 func (n noopLogger) Named(_ string) mtglib.Logger          { return n }
 func (n noopLogger) BindInt(_ string, _ int) mtglib.Logger { return n }
 func (n noopLogger) BindStr(_, _ string) mtglib.Logger     { return n }
+func (n noopLogger) BindJSON(_, _ string) mtglib.Logger    { return n }
 func (n noopLogger) Printf(_ string, _ ...interface{})     {}
 func (n noopLogger) Info(_ string)                         {}
 func (n noopLogger) Warning(_ string)                      {}

logger/zerolog.go

@@ -15,6 +15,7 @@ const (
 	zeroLogContextVarTypeUnknown zeroLogContextVarType = iota
 	zeroLogContextVarTypeStr
 	zeroLogContextVarTypeInt
+	zeroLogContextVarTypeJSON
 )
 
 type zeroLogContext struct {
@@ -66,6 +67,17 @@ func (z *zeroLogContext) BindStr(name, value string) mtglib.Logger {
 	}
 }
 
+func (z *zeroLogContext) BindJSON(name, value string) mtglib.Logger {
+	return &zeroLogContext{
+		name:       z.name,
+		log:        z.log,
+		ctxVarType: zeroLogContextVarTypeJSON,
+		ctxVarName: name,
+		ctxVarStr:  value,
+		parent:     z,
+	}
+}
+
 func (z *zeroLogContext) Printf(format string, args ...interface{}) {
 	z.Debug(fmt.Sprintf(format, args...))
 }
@@ -110,6 +122,8 @@ func (z *zeroLogContext) attachCtx(evt *zerolog.Event) {
 		evt.Str(z.ctxVarName, z.ctxVarStr)
 	case zeroLogContextVarTypeInt:
 		evt.Int(z.ctxVarName, z.ctxVarInt)
+	case zeroLogContextVarTypeJSON:
+		evt.RawJSON(z.ctxVarName, []byte(z.ctxVarStr))
 	case zeroLogContextVarTypeUnknown:
 	}
 }

mtglib/init.go

@@ -69,6 +69,9 @@ const (
 
 	// DefaultIdleTimeout is a default timeout for closing a connection
 	// in case of idling.
+	//
+	// Deprecated: no longer in use because of changed TCP relay
+	// algorithm.
 	DefaultIdleTimeout = time.Minute
 
 	// DefaultTolerateTimeSkewness is a default timeout for time
@@ -83,9 +86,14 @@ const (
 	// by Telegram and a proxy.
 	SecretKeyLength = 16
 
-	// ConnectionIDBytesLength defines a count of random bytes
+	// ConnectionIDBytesLength defines a count of random bytes used to generate
-	// used to generate a stream/connection ids.
+	// a stream/connection ids.
 	ConnectionIDBytesLength = 16
+
+	// TCPRelayReadTimeout defines a max time period between two consecuitive
+	// reads from Telegram after which connection will be terminated. This is
+	// required to abort stale connections.
+	TCPRelayReadTimeout = 20 * time.Second
 )
 
 // Network defines a knowledge how to work with a network. It may sound
@@ -237,6 +245,9 @@ type Logger interface {
 	// BindStr binds new string parameter to a new logger instance.
 	BindStr(name, value string) Logger
 
+	// BindJSON binds a new JSON-encoded string to a new logger instance.
+	BindJSON(name, value string) Logger
+
 	// Printf is to support log.Logger behavior.
 	Printf(format string, args ...interface{})
 

mtglib/init_internal_test.go

@@ -11,6 +11,7 @@ type NoopLogger struct{}
 func (n NoopLogger) Named(_ string) Logger             { return n }
 func (n NoopLogger) BindInt(_ string, _ int) Logger    { return n }
 func (n NoopLogger) BindStr(_, _ string) Logger        { return n }
+func (n NoopLogger) BindJSON(_, _ string) Logger       { return n }
 func (n NoopLogger) Printf(_ string, _ ...interface{}) {}
 func (n NoopLogger) Info(_ string)                     {}
 func (n NoopLogger) Warning(_ string)                  {}

mtglib/internal/faketls/conn.go

@@ -46,7 +46,11 @@ func (c *Conn) Write(p []byte) (int, error) {
 
 	rec.Type = record.TypeApplicationData
 	rec.Version = record.Version12
-	written := 0
+
+	sendBuffer := acquireBytesBuffer()
+	defer releaseBytesBuffer(sendBuffer)
+
+	lenP := len(p)
 
 	for len(p) > 0 {
 		chunkSize := rand.Intn(record.TLSMaxRecordSize)
@@ -56,14 +60,14 @@ func (c *Conn) Write(p []byte) (int, error) {
 
 		rec.Payload.Reset()
 		rec.Payload.Write(p[:chunkSize])
+		rec.Dump(sendBuffer) // nolint: errcheck
 
-		if err := rec.Dump(c.Conn); err != nil {
-			return written, err // nolint: wrapcheck
-		}
-
-		written += chunkSize
 		p = p[chunkSize:]
 	}
 
-	return written, nil
+	if _, err := c.Conn.Write(sendBuffer.Bytes()); err != nil {
+		return 0, err // nolint: wrapcheck
+	}
+
+	return lenP, nil
 }

mtglib/internal/relay/conn.go

@@ -1,35 +1,19 @@
 package relay
 
 import (
-	"context"
+	"fmt"
-	"io"
+	"net"
+	"time"
 )
 
 type conn struct {
-	io.ReadWriteCloser
+	net.Conn
-
-	ctx         context.Context
-	tickChannel chan struct{}
 }
 
 func (c conn) Read(p []byte) (int, error) {
-	n, err := c.ReadWriteCloser.Read(p)
+	if err := c.SetReadDeadline(time.Now().Add(getTimeout())); err != nil {
-
+		return 0, fmt.Errorf("cannot set read deadline: %w", err)
-	select {
-	case <-c.ctx.Done():
-	case c.tickChannel <- struct{}{}:
 	}
 
-	return n, err // nolint: wrapcheck
+	return c.Conn.Read(p) // nolint: wrapcheck
-}
-
-func (c conn) Write(p []byte) (int, error) {
-	n, err := c.ReadWriteCloser.Write(p)
-
-	select {
-	case <-c.ctx.Done():
-	case c.tickChannel <- struct{}{}:
-	}
-
-	return n, err // nolint: wrapcheck
 }

mtglib/internal/relay/conn_internal_test.go

@@ -1,125 +0,0 @@
-package relay
-
-import (
-	"context"
-	"errors"
-	"io"
-	"testing"
-
-	"github.com/9seconds/mtg/v2/internal/testlib"
-	"github.com/stretchr/testify/mock"
-	"github.com/stretchr/testify/suite"
-)
-
-type ConnTestSuite struct {
-	suite.Suite
-
-	ctxCancel   context.CancelFunc
-	connMock    *testlib.NetConnMock
-	tickChannel chan struct{}
-	buf         []byte
-	c           conn
-}
-
-func (suite *ConnTestSuite) SetupTest() {
-	ctx, cancel := context.WithCancel(context.Background())
-
-	suite.tickChannel = make(chan struct{}, 1)
-	suite.connMock = &testlib.NetConnMock{}
-	suite.ctxCancel = cancel
-	suite.buf = make([]byte, 5)
-
-	suite.c = conn{
-		ReadWriteCloser: suite.connMock,
-		ctx:             ctx,
-		tickChannel:     suite.tickChannel,
-	}
-}
-
-func (suite *ConnTestSuite) TestReadOk() {
-	suite.connMock.On("Read", mock.Anything).Once().Return(len(suite.buf), nil)
-
-	n, err := suite.c.Read(suite.buf)
-	suite.NoError(err)
-	suite.Equal(len(suite.buf), n)
-
-	select {
-	case <-suite.tickChannel:
-	default:
-		suite.FailNow("cannot find a tick event")
-	}
-}
-
-func (suite *ConnTestSuite) TestReadErr() {
-	suite.connMock.On("Read", mock.Anything).Once().Return(0, io.EOF)
-
-	_, err := suite.c.Read(suite.buf)
-	suite.True(errors.Is(err, io.EOF))
-
-	select {
-	case <-suite.tickChannel:
-	default:
-		suite.FailNow("cannot find a tick event")
-	}
-}
-
-func (suite *ConnTestSuite) TestReadContextDone() {
-	suite.connMock.On("Read", mock.Anything).Once().Return(len(suite.buf), nil)
-	suite.ctxCancel()
-
-	suite.tickChannel <- struct{}{}
-
-	suite.c.Read(suite.buf) // nolint: errcheck
-}
-
-func (suite *ConnTestSuite) TestWriteOk() {
-	suite.connMock.On("Write", mock.Anything).Once().Return(len(suite.buf), nil)
-
-	n, err := suite.c.Write(suite.buf)
-	suite.NoError(err)
-	suite.Equal(len(suite.buf), n)
-
-	select {
-	case <-suite.tickChannel:
-	default:
-		suite.FailNow("cannot find a tick event")
-	}
-}
-
-func (suite *ConnTestSuite) TestWriteErr() {
-	suite.connMock.On("Write", mock.Anything).Once().Return(0, io.EOF)
-
-	_, err := suite.c.Write(suite.buf)
-	suite.True(errors.Is(err, io.EOF))
-
-	select {
-	case <-suite.tickChannel:
-	default:
-		suite.FailNow("cannot find a tick event")
-	}
-}
-
-func (suite *ConnTestSuite) TestWriteContextDone() {
-	suite.connMock.On("Write", mock.Anything).Once().Return(len(suite.buf), nil)
-	suite.ctxCancel()
-
-	suite.tickChannel <- struct{}{}
-
-	suite.c.Write(suite.buf) // nolint: errcheck
-}
-
-func (suite *ConnTestSuite) TearDownTest() {
-	select {
-	case <-suite.tickChannel:
-	default:
-	}
-
-	close(suite.tickChannel)
-
-	suite.connMock.AssertExpectations(suite.T())
-}
-
-func TestConn(t *testing.T) {
-	t.Parallel()
-	suite.Run(t, &ConnTestSuite{})
-}

mtglib/internal/relay/init.go

@@ -1,5 +1,14 @@
 package relay
 
+import "time"
+
+const (
+	ConnectionTimeToLiveMin = 2 * time.Minute
+	ConnectionTimeToLiveMax = 10 * time.Minute
+	TimeoutMin              = 20 * time.Second
+	TimeoutMax              = time.Minute
+)
+
 type Logger interface {
 	Printf(msg string, args ...interface{})
 }

mtglib/internal/relay/init_test.go

@@ -1,49 +1,5 @@
 package relay_test
 
-import (
-	"bytes"
-	"io"
-	"sync"
-)
-
 type loggerMock struct{}
 
 func (l loggerMock) Printf(format string, args ...interface{}) {}
-
-type rwcMock struct {
-	bytes.Buffer
-
-	closed bool
-	mutex  sync.Mutex
-}
-
-func (r *rwcMock) Read(p []byte) (int, error) {
-	r.mutex.Lock()
-	defer r.mutex.Unlock()
-
-	if r.closed {
-		return 0, io.EOF
-	}
-
-	return r.Buffer.Read(p) // nolint: wrapcheck
-}
-
-func (r *rwcMock) Write(p []byte) (int, error) {
-	r.mutex.Lock()
-	defer r.mutex.Unlock()
-
-	if r.closed {
-		return 0, io.EOF
-	}
-
-	return r.Buffer.Write(p) // nolint: wrapcheck
-}
-
-func (r *rwcMock) Close() error {
-	r.mutex.Lock()
-	defer r.mutex.Unlock()
-
-	r.closed = true
-
-	return nil
-}

mtglib/internal/relay/pools.go

@@ -1,45 +1,32 @@
 package relay
 
-import (
+import "sync"
-	"context"
-	"sync"
-	"time"
-)
 
-var relayPool = sync.Pool{
+type eastWest struct {
-	New: func() interface{} {
+	east []byte
-		return &Relay{
+	west []byte
-			tickChannel:  make(chan struct{}),
-			errorChannel: make(chan error, 1),
 }
+
+var eastWestPool = sync.Pool{
+	New: func() interface{} {
+		return &eastWest{}
 	},
 }
 
-func AcquireRelay(ctx context.Context, logger Logger, bufferSize int, idleTimeout time.Duration) *Relay {
+func acquireEastWest(bufferSize int) *eastWest {
-	ctx, cancel := context.WithCancel(ctx)
+	wanted := eastWestPool.Get().(*eastWest) // nolint: forcetypeassert
 
-	r, ok := relayPool.Get().(*Relay)
+	if len(wanted.east) != bufferSize {
-	if !ok {
+		wanted.east = make([]byte, bufferSize)
-		panic("Relay pool has no relay!")
 	}
 
-	r.ctx = ctx
+	if len(wanted.west) != bufferSize {
-	r.ctxCancel = cancel
+		wanted.west = make([]byte, bufferSize)
-	r.logger = logger
-	r.tickTimeout = idleTimeout
-
-	if len(r.eastBuffer) != bufferSize {
-		r.eastBuffer = make([]byte, bufferSize)
 	}
 
-	if len(r.westBuffer) != bufferSize {
+	return wanted
-		r.westBuffer = make([]byte, bufferSize)
 }
 
-	return r
+func releaseEastWest(ew *eastWest) {
-}
+	eastWestPool.Put(ew)
-
-func ReleaseRelay(r *Relay) {
-	r.Reset()
-	relayPool.Put(r)
 }

mtglib/internal/relay/relay.go

@@ -3,127 +3,48 @@ package relay
 import (
 	"context"
 	"io"
+	"net"
 	"sync"
-	"time"
 )
 
-type Relay struct {
+func Relay(ctx context.Context, log Logger, bufferSize int,
-	ctx          context.Context
+	telegramConn net.Conn, clientConn io.ReadWriteCloser) {
-	ctxCancel    context.CancelFunc
+	defer telegramConn.Close()
-	logger       Logger
+	defer clientConn.Close()
-	processMutex sync.Mutex
-	eastBuffer   []byte
-	westBuffer   []byte
-	tickChannel  chan struct{}
-	errorChannel chan error
-	tickTimeout  time.Duration
-}
 
-func (r *Relay) Reset() {
+	ctx, cancel := context.WithTimeout(ctx, getConnectionTimeToLive())
-	r.processMutex.Lock()
+	defer cancel()
-	defer r.processMutex.Unlock()
 
-	if r.ctxCancel != nil {
+	go func() {
-		r.ctxCancel()
+		<-ctx.Done()
-	}
+		telegramConn.Close()
+		clientConn.Close()
+	}()
 
-	r.ctx = nil
+	buffers := acquireEastWest(bufferSize)
-	r.ctxCancel = nil
+	defer releaseEastWest(buffers)
-	r.logger = nil
-}
 
-func (r *Relay) Process(eastConn, westConn io.ReadWriteCloser) error {
+	telegramConn = conn{
-	r.processMutex.Lock()
+		Conn: telegramConn,
-	defer r.processMutex.Unlock()
-
-	eastConn = conn{
-		ReadWriteCloser: eastConn,
-		ctx:             r.ctx,
-		tickChannel:     r.tickChannel,
-	}
-	westConn = conn{
-		ReadWriteCloser: westConn,
-		ctx:             r.ctx,
-		tickChannel:     r.tickChannel,
 	}
 
 	wg := &sync.WaitGroup{}
-	wg.Add(3) // nolint: gomnd
+	wg.Add(2) // nolint: gomnd
 
-	go r.runObserver(eastConn, westConn, wg)
+	go pump(log, telegramConn, clientConn, wg, buffers.east, "east -> west")
 
-	go r.transmit(eastConn, westConn, r.westBuffer, "west", wg)
+	pump(log, clientConn, telegramConn, wg, buffers.west, "west -> east")
-
-	r.transmit(westConn, eastConn, r.eastBuffer, "east", wg)
 
 	wg.Wait()
-
-	select {
-	case err := <-r.errorChannel:
-		return err
-	default:
-		return nil
-	}
 }
 
-func (r *Relay) transmit(src io.ReadCloser, dst io.WriteCloser,
+func pump(log Logger, src io.ReadCloser, dst io.WriteCloser, wg *sync.WaitGroup,
-	buffer []byte, direction string, wg *sync.WaitGroup) {
+	buf []byte, direction string) {
 	defer wg.Done()
+	defer src.Close()
+	defer dst.Close()
 
-	defer func() {
+	if n, err := io.CopyBuffer(dst, src, buf); err != nil {
-		r.ctxCancel()
+		log.Printf("cannot pump %s (written %d bytes): %w", direction, n, err)
-		src.Close()
-		dst.Close()
-	}()
-
-	if _, err := io.CopyBuffer(dst, src, buffer); err != nil {
-		r.logger.Printf("error '%v' happened on direction %s", err, direction)
-
-		select {
-		case <-r.ctx.Done():
-			err = r.ctx.Err()
-		default:
-		}
-
-		select {
-		case r.errorChannel <- err:
-		default:
-		}
-	}
-}
-
-func (r *Relay) runObserver(one, another io.Closer, wg *sync.WaitGroup) {
-	defer wg.Done()
-
-	ticker := time.NewTicker(time.Second)
-
-	defer func() {
-		one.Close()
-		another.Close()
-
-		ticker.Stop()
-
-		select {
-		case <-ticker.C:
-		default:
-		}
-	}()
-
-	lastTickAt := time.Now()
-
-	for {
-		select {
-		case <-r.ctx.Done():
-			return
-		case <-r.tickChannel:
-			lastTickAt = time.Now()
-		case <-ticker.C:
-			if time.Since(lastTickAt) > r.tickTimeout {
-				r.logger.Printf("exit due to a timeout")
-				r.ctxCancel()
-
-				return
-			}
-		}
 	}
 }

mtglib/internal/relay/relay_test.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"io"
 	"testing"
-	"time"
 
 	"github.com/9seconds/mtg/v2/internal/testlib"
 	"github.com/9seconds/mtg/v2/mtglib/internal/relay"
@@ -15,60 +14,40 @@ import (
 type RelayTestSuite struct {
 	suite.Suite
 
+	loggerMock       relay.Logger
 	ctx              context.Context
 	ctxCancel        context.CancelFunc
-	r         *relay.Relay
+	telegramConnMock *testlib.NetConnMock
+	clientConnMock   *testlib.NetConnMock
 }
 
 func (suite *RelayTestSuite) SetupTest() {
-	suite.ctx, suite.ctxCancel = context.WithCancel(context.Background())
+	ctx, cancel := context.WithCancel(context.Background())
-	suite.r = relay.AcquireRelay(suite.ctx, loggerMock{}, 4096, time.Second)
+	suite.ctx = ctx
+	suite.ctxCancel = cancel
+	suite.loggerMock = &loggerMock{}
+	suite.telegramConnMock = &testlib.NetConnMock{}
+	suite.clientConnMock = &testlib.NetConnMock{}
 }
 
 func (suite *RelayTestSuite) TearDownTest() {
 	suite.ctxCancel()
-	relay.ReleaseRelay(suite.r)
+	suite.telegramConnMock.AssertExpectations(suite.T())
-	suite.r = nil
+	suite.clientConnMock.AssertExpectations(suite.T())
 }
 
-func (suite *RelayTestSuite) TestCancelled() {
+func (suite *RelayTestSuite) TestExit() {
-	suite.ctxCancel()
+	suite.telegramConnMock.On("SetReadDeadline", mock.Anything).Return(nil)
+	suite.telegramConnMock.On("Close").Return(nil)
+	suite.telegramConnMock.On("Read", mock.Anything).Return(10, io.EOF).Once()
+	suite.telegramConnMock.On("Write", mock.Anything).Return(10, io.EOF).Maybe()
 
-	eastConn := &rwcMock{}
+	suite.clientConnMock.On("Read", mock.Anything).Return(0, io.EOF).Once()
-	eastConn.Write([]byte{1, 2, 3, 4, 5}) // nolint: errcheck
+	suite.clientConnMock.On("Write", mock.Anything).Return(10, io.EOF).Maybe()
+	suite.clientConnMock.On("Close").Return(nil)
 
-	westConn := &rwcMock{}
+	relay.Relay(suite.ctx, suite.loggerMock, 1024,
-	westConn.Write([]byte{100, 101, 102}) // nolint: errcheck
+		suite.telegramConnMock, suite.clientConnMock)
-
-	suite.Nil(suite.r.Process(eastConn, westConn))
-}
-
-func (suite *RelayTestSuite) TestCopyFine() {
-	eastConn := &rwcMock{}
-	eastConn.Write([]byte{1, 2, 3, 4, 5}) // nolint: errcheck
-
-	westConn := &rwcMock{}
-	westConn.Write([]byte{100, 101, 102}) // nolint: errcheck
-
-	// yes, this test is not good enough. but apparently, if it hangs,
-	// we can debug most of possible issues.
-	_ = suite.r.Process(eastConn, westConn)
-}
-
-func (suite *RelayTestSuite) TestTimeout() {
-	eastConn := &rwcMock{}
-	eastConn.Write([]byte{1, 2, 3, 4, 5}) // nolint: errcheck
-
-	westConn := &testlib.NetConnMock{}
-	westConn.On("Close").Return(nil)
-	westConn.On("Read", mock.Anything).Return(0, io.EOF).Run(func(_ mock.Arguments) {
-		time.Sleep(2 * time.Second)
-	})
-	westConn.On("Write", mock.Anything).Return(0, io.EOF).Run(func(_ mock.Arguments) {
-		time.Sleep(2 * time.Second)
-	})
-
-	suite.Error(suite.r.Process(eastConn, westConn))
 }
 
 func TestRelay(t *testing.T) {

mtglib/internal/relay/timeouts.go

@@ -0,0 +1,22 @@
+package relay
+
+import (
+	"math/rand"
+	"time"
+)
+
+func getConnectionTimeToLive() time.Duration {
+	return getTime(ConnectionTimeToLiveMin, ConnectionTimeToLiveMax)
+}
+
+func getTimeout() time.Duration {
+	return getTime(TimeoutMin, TimeoutMax)
+}
+
+func getTime(minDuration, maxDuration time.Duration) time.Duration {
+	minDurationInSeconds := int(minDuration.Seconds())
+	maxDurationInSeconds := int(maxDuration.Seconds())
+	number := minDurationInSeconds + rand.Intn(maxDurationInSeconds-minDurationInSeconds)
+
+	return time.Duration(number) * time.Second
+}

mtglib/internal/relay/timeouts_internal_test.go

@@ -0,0 +1,37 @@
+package relay
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/suite"
+)
+
+type TimeoutsTestSuite struct {
+	suite.Suite
+}
+
+func (suite *TimeoutsTestSuite) TestGetConnectionTimeToLive() {
+	for i := 0; i < 100; i++ {
+		value := getConnectionTimeToLive()
+		message := fmt.Sprintf("generated value is %v", value)
+
+		suite.GreaterOrEqual(value, ConnectionTimeToLiveMin, message)
+		suite.LessOrEqual(value, ConnectionTimeToLiveMax, message)
+	}
+}
+
+func (suite *TimeoutsTestSuite) TestGetTimeout() {
+	for i := 0; i < 100; i++ {
+		value := getTimeout()
+		message := fmt.Sprintf("generated value is %v", value)
+
+		suite.GreaterOrEqual(value, TimeoutMin, message)
+		suite.LessOrEqual(value, TimeoutMax, message)
+	}
+}
+
+func TestTimeouts(t *testing.T) {
+	t.Parallel()
+	suite.Run(t, &TimeoutsTestSuite{})
+}

mtglib/internal/telegram/address_pool.go

@@ -7,6 +7,14 @@ type addressPool struct {
 	v6 [][]tgAddr
 }
 
+func (a addressPool) isValidDC(dc int) bool {
+	return dc > 0 && dc <= len(a.v4) && dc <= len(a.v6)
+}
+
+func (a addressPool) getRandomDC() int {
+	return 1 + rand.Intn(len(a.v4))
+}
+
 func (a addressPool) getV4(dc int) []tgAddr {
 	return a.get(a.v4, dc-1)
 }

mtglib/internal/telegram/telegram.go

@@ -42,6 +42,14 @@ func (t Telegram) Dial(ctx context.Context, dc int) (net.Conn, error) {
 	return nil, fmt.Errorf("cannot dial to %d dc: %w", dc, err)
 }
 
+func (t Telegram) IsKnownDC(dc int) bool {
+	return t.pool.isValidDC(dc)
+}
+
+func (t Telegram) GetFallbackDC() int {
+	return t.pool.getRandomDC()
+}
+
 func New(dialer Dialer, ipPreference string, useTestDCs bool) (*Telegram, error) {
 	var pref preferIP
 

mtglib/internal/telegram/telegram_internal_test.go

@@ -44,6 +44,7 @@ func (suite *TelegramTestSuite) TestUnknownDC() {
 		suite.T().Run(strconv.Itoa(value), func(t *testing.T) {
 			_, err := suite.t.Dial(context.Background(), value)
 			assert.Error(t, err)
+			assert.False(t, suite.t.IsKnownDC(value))
 		})
 	}
 }
@@ -71,6 +72,7 @@ func (suite *TelegramTestSuite) TestDialToCorrectIPs() {
 
 			_, err := suite.t.Dial(context.Background(), idx)
 			assert.True(t, errors.Is(err, io.EOF))
+			assert.True(t, suite.t.IsKnownDC(idx))
 		})
 	}
 }
@@ -135,6 +137,22 @@ func (suite *TelegramTestSuite) TestUnknownPreferIP() {
 	suite.Error(err)
 }
 
+func (suite *TelegramTestSuite) TestFallbackDC() {
+	dcs := make([]int, 10)
+
+	for i := 0; i < len(dcs); i++ {
+		dcs[i] = suite.t.GetFallbackDC()
+	}
+
+	for _, v := range dcs {
+		value := v
+
+		suite.T().Run(strconv.Itoa(value), func(t *testing.T) {
+			assert.True(t, suite.t.IsKnownDC(value))
+		})
+	}
+}
+
 func TestTelegram(t *testing.T) {
 	t.Parallel()
 	suite.Run(t, &TelegramTestSuite{})

mtglib/proxy.go

@@ -23,7 +23,7 @@ type Proxy struct {
 	ctxCancel       context.CancelFunc
 	streamWaitGroup sync.WaitGroup
 
-	idleTimeout          time.Duration
+	allowFallbackOnUnknownDC bool
 	tolerateTimeSkewness     time.Duration
 	bufferSize               int
 	domainFrontingPort       int
@@ -81,13 +81,13 @@ func (p *Proxy) ServeConn(conn net.Conn) {
 		return
 	}
 
-	rel := relay.AcquireRelay(ctx,
+	relay.Relay(
-		p.logger.Named("relay"), p.bufferSize, p.idleTimeout)
+		ctx,
-	defer relay.ReleaseRelay(rel)
+		ctx.logger.Named("relay"),
-
+		p.bufferSize,
-	if err := rel.Process(ctx.clientConn, ctx.telegramConn); err != nil {
+		ctx.telegramConn,
-		p.logger.DebugError("relay has been finished", err)
+		ctx.clientConn,
-	}
+	)
 }
 
 // Serve starts a proxy on a given listener.
@@ -208,7 +208,16 @@ func (p *Proxy) doObfuscated2Handshake(ctx *streamContext) error {
 }
 
 func (p *Proxy) doTelegramCall(ctx *streamContext) error {
-	conn, err := p.telegram.Dial(ctx, ctx.dc)
+	dc := ctx.dc
+
+	if p.allowFallbackOnUnknownDC && !p.telegram.IsKnownDC(dc) {
+		dc = p.telegram.GetFallbackDC()
+		ctx.logger = ctx.logger.BindInt("fallback_dc", dc)
+
+		ctx.logger.Warning("unknown DC, fallbacks")
+	}
+
+	conn, err := p.telegram.Dial(ctx, dc)
 	if err != nil {
 		return fmt.Errorf("cannot dial to Telegram: %w", err)
 	}
@@ -255,13 +264,13 @@ func (p *Proxy) doDomainFronting(ctx *streamContext, conn *connRewind) {
 		stream:   p.eventStream,
 	}
 
-	rel := relay.AcquireRelay(ctx,
+	relay.Relay(
-		p.logger.Named("domain-fronting"), p.bufferSize, p.idleTimeout)
+		ctx,
-	defer relay.ReleaseRelay(rel)
+		ctx.logger.Named("domain-fronting"),
-
+		p.bufferSize,
-	if err := rel.Process(conn, frontConn); err != nil {
+		frontConn,
-		p.logger.DebugError("domain fronting relay has been finished", err)
+		conn,
-	}
+	)
 }
 
 // NewProxy makes a new proxy instance.
@@ -287,8 +296,8 @@ func NewProxy(opts ProxyOpts) (*Proxy, error) {
 		logger:                   opts.getLogger("proxy"),
 		domainFrontingPort:       opts.getDomainFrontingPort(),
 		tolerateTimeSkewness:     opts.getTolerateTimeSkewness(),
-		idleTimeout:          opts.getIdleTimeout(),
 		bufferSize:               opts.getBufferSize(),
+		allowFallbackOnUnknownDC: opts.AllowFallbackOnUnknownDC,
 		telegram:                 tg,
 	}
 

mtglib/proxy_opts.go

@@ -90,6 +90,16 @@ type ProxyOpts struct {
 	// This is an optional setting.
 	DomainFrontingPort uint
 
+	// AllowFallbackOnUnknownDC defines how proxy behaves if unknown DC was
+	// requested. If this setting is set to false, then such connection
+	// will be rejected. Otherwise, proxy will chose any DC.
+	//
+	// Telegram is designed in a way that any DC can serve any request,
+	// the problem is a latency.
+	//
+	// This is an optional setting.
+	AllowFallbackOnUnknownDC bool
+
 	// UseTestDCs defines if we have to connect to production or to staging
 	// DCs of Telegram.
 	//
@@ -143,14 +153,6 @@ func (p ProxyOpts) getDomainFrontingPort() int {
 	return int(p.DomainFrontingPort)
 }
 
-func (p ProxyOpts) getIdleTimeout() time.Duration {
-	if p.IdleTimeout == 0 {
-		return DefaultIdleTimeout
-	}
-
-	return p.IdleTimeout
-}
-
 func (p ProxyOpts) getTolerateTimeSkewness() time.Duration {
 	if p.TolerateTimeSkewness == 0 {
 		return DefaultTolerateTimeSkewness

network/default.go

@@ -5,8 +5,6 @@ import (
 	"fmt"
 	"net"
 	"time"
-
-	"github.com/libp2p/go-reuseport"
 )
 
 type defaultDialer struct {
@@ -31,36 +29,14 @@ func (d *defaultDialer) DialContext(ctx context.Context, network, address string
 		return nil, fmt.Errorf("cannot dial to %s: %w", address, err)
 	}
 
-	tcpConn, ok := conn.(*net.TCPConn)
+	// we do not need to call to end user. End users call us.
-	if !ok {
+	if err := SetServerSocketOptions(conn, d.bufferSize); err != nil {
-		panic("conn type is not tcp")
-	}
-
-	if err := tcpConn.SetNoDelay(true); err != nil {
 		conn.Close()
 
-		return nil, fmt.Errorf("cannot set TCP_NO_DELAY: %w", err)
+		return nil, fmt.Errorf("cannot set socket options: %w", err)
 	}
 
-	if err := tcpConn.SetReadBuffer(d.bufferSize); err != nil {
+	return conn, nil
-		tcpConn.Close()
-
-		return nil, fmt.Errorf("cannot set read buffer size: %w", err)
-	}
-
-	if err := tcpConn.SetWriteBuffer(d.bufferSize); err != nil {
-		tcpConn.Close()
-
-		return nil, fmt.Errorf("cannot set write buffer size: %w", err)
-	}
-
-	if err := tcpConn.SetKeepAlive(true); err != nil {
-		tcpConn.Close()
-
-		return nil, fmt.Errorf("cannot enable keep-alive: %w", err)
-	}
-
-	return tcpConn, nil
 }
 
 // NewDefaultDialer build a new dialer which dials bypassing proxies
@@ -87,7 +63,6 @@ func NewDefaultDialer(timeout time.Duration, bufferSize int) (Dialer, error) {
 	return &defaultDialer{
 		Dialer: net.Dialer{
 			Timeout: timeout,
-			Control: reuseport.Control,
 		},
 		bufferSize: bufferSize,
 	}, nil

network/init.go

@@ -70,6 +70,10 @@ const (
 
 	// DNSTimeout defines a timeout for DNS queries.
 	DNSTimeout = 5 * time.Second
+
+	// tcpLingerTimeout defines a number of seconds to wait for sending
+	// unacknowledged data.
+	tcpLingerTimeout = 1
 )
 
 var (

network/sockopts.go

@@ -0,0 +1,59 @@
+package network
+
+import (
+	"fmt"
+	"net"
+)
+
+// SetClientSocketOptions tunes a TCP socket that represents a connection to
+// end user (not Telegram service or fronting domain).
+func SetClientSocketOptions(conn net.Conn, bufferSize int) error {
+	tcpConn := conn.(*net.TCPConn) // nolint: forcetypeassert
+
+	if err := tcpConn.SetNoDelay(false); err != nil {
+		return fmt.Errorf("cannot disable TCP_NO_DELAY: %w", err)
+	}
+
+	return setCommonSocketOptions(tcpConn, bufferSize)
+}
+
+// SetServerSocketOptions tunes a TCP socket that represents a connection to
+// remote server like Telegram or fronting domain (but not end user).
+func SetServerSocketOptions(conn net.Conn, bufferSize int) error {
+	tcpConn := conn.(*net.TCPConn) // nolint: forcetypeassert
+
+	if err := tcpConn.SetNoDelay(true); err != nil {
+		return fmt.Errorf("cannot enable TCP_NO_DELAY: %w", err)
+	}
+
+	return setCommonSocketOptions(tcpConn, bufferSize)
+}
+
+func setCommonSocketOptions(conn *net.TCPConn, bufferSize int) error {
+	if err := conn.SetReadBuffer(bufferSize); err != nil {
+		return fmt.Errorf("cannot set read buffer size: %w", err)
+	}
+
+	if err := conn.SetWriteBuffer(bufferSize); err != nil {
+		return fmt.Errorf("cannot set write buffer size: %w", err)
+	}
+
+	if err := conn.SetKeepAlive(false); err != nil {
+		return fmt.Errorf("cannot disable TCP keepalive probes: %w", err)
+	}
+
+	if err := conn.SetLinger(tcpLingerTimeout); err != nil {
+		return fmt.Errorf("cannot set TCP linger timeout: %w", err)
+	}
+
+	rawConn, err := conn.SyscallConn()
+	if err != nil {
+		return fmt.Errorf("cannot get underlying raw connection: %w", err)
+	}
+
+	if err := setSocketReuseAddrPort(rawConn, bufferSize); err != nil {
+		return fmt.Errorf("cannot setup SO_REUSEADDR/PORT: %w", err)
+	}
+
+	return nil
+}

network/sockopts_unix.go

@@ -0,0 +1,31 @@
+//go:build !windows
+// +build !windows
+
+package network
+
+import (
+	"fmt"
+	"syscall"
+
+	"golang.org/x/sys/unix"
+)
+
+func setSocketReuseAddrPort(conn syscall.RawConn, bufferSize int) error {
+	var err error
+
+	conn.Control(func(fd uintptr) { // nolint: errcheck
+		err = unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_REUSEADDR, 1)
+		if err != nil {
+			err = fmt.Errorf("cannot set SO_REUSEADDR: %w", err)
+
+			return
+		}
+
+		err = unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_REUSEPORT, 1)
+		if err != nil {
+			err = fmt.Errorf("cannot set SO_REUSEPORT: %w", err)
+		}
+	})
+
+	return err
+}

network/sockopts_windows.go

@@ -0,0 +1,10 @@
+//go:build windows
+// +build windows
+
+package network
+
+import "syscall"
+
+func setSocketReuseAddrPort(conn syscall.RawConn, bufferSize int) error {
+	return nil
+}