First version

.github/workflows/ci.yaml

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+name: CI
+
+on:
+    push:
+    pull_request:
+
+jobs:
+    build:
+        name: Build
+        runs-on: ubuntu-18.04
+        steps:
+            -   uses: actions/checkout@v2
+            -   uses: actions/setup-go@v2
+            -   name: Install dependencies
+                run: sudo apt update && sudo apt install libsnmp-dev
+            -   name: Build
+                run: go build ./cmd/snmp-proxy
+
+    test:
+        name: Test
+        runs-on: ubuntu-18.04
+        steps:
+            -   uses: actions/checkout@v2
+            -   uses: actions/setup-go@v2
+            -   name: Install dependencies
+                run: sudo apt update && sudo apt install libsnmp-dev python3-pip snmp-mibs-downloader
+            -   name: Install snmpsim
+                run: sudo pip3 install snmpsim
+            -   name: Run tests
+                run: make test
+
+    coverage:
+        name: Code Coverage
+        runs-on: ubuntu-18.04
+        steps:
+            -   uses: actions/checkout@v2
+            -   uses: actions/setup-go@v2
+            -   name: Install dependencies
+                run: sudo apt update && sudo apt install libsnmp-dev python3-pip snmp-mibs-downloader
+            -   name: Install snmpsim
+                run: sudo pip3 install snmpsim
+            -   name: Download go-acc
+                run: GO111MODULE=off go get -u github.com/ory/go-acc
+            -   name: Generate Code Coverage
+                run: $(go env GOPATH)/bin/go-acc --covermode set --output coverage.cov ./...
+            -   name: Send coverage
+                uses: shogo82148/actions-goveralls@v1
+                with:
+                    path-to-profile: coverage.cov
+
+    lint:
+        name: Lint
+        runs-on: ubuntu-18.04
+        steps:
+            -   uses: actions/checkout@v2
+            -   name: Install dependencies
+                run: sudo apt update && sudo apt install libsnmp-dev
+            -   name: golangci-lint
+                uses: golangci/golangci-lint-action@v1
+                with:
+                    version: v1.27

.github/workflows/release.yaml

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+name: Release
+
+on:
+    push:
+        tags:
+            - v*
+
+jobs:
+    release:
+        name: Release
+        runs-on: ubuntu-18.04
+        steps:
+            -   name: Checkout
+                uses: actions/checkout@v2
+                with:
+                    fetch-depth: 0
+            -   uses: actions/setup-go@v2
+            -   name: Install dependencies
+                run: sudo apt update && sudo apt install libsnmp-dev
+            -   name: GoReleaser
+                uses: goreleaser/goreleaser-action@v2
+                with:
+                    args: release
+                env:
+                    GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.gitignore

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+/bin
+/dist
+
+/config.toml
+/snmp-proxy

.golangci.yml

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+run:
+    modules-download-mode: readonly
+
+linters:
+    enable-all: true
+    disable:
+        - depguard
+        - dogsled
+        - funlen
+        - godox
+        - gofmt
+        - golint
+        - gomnd
+        - interfacer
+
+linters-settings:
+    gocritic:
+        disabled-checks:
+            - captLocal
+
+    govet:
+        enable-all: true
+        disable:
+            - shadow
+
+    lll:
+        tab-width: 4
+
+    wsl:
+        allow-cuddle-declarations: true
+
+issues:
+    max-issues-per-linter: 0
+    max-same-issues: 0
+    exclude-rules:
+        # ignore unchecked errors and missing Close() calls in tests
+        -   path: _test\.go
+            linters: [errcheck, bodyclose]
+        # ignore recommendations for variable names, e.g id => ID, uri => URI, ...
+        -   text: "^ST1003:"
+            linters: [stylecheck]
+        # ignore line length limit in tests
+        -   path: _test\.go
+            text: line is \d+ characters
+            linters: [lll]
+        # ignore defer cuddle in tests
+        -   path: _test\.go
+            text: only one cuddle assignment allowed before defer statement
+            linters: [wsl]
+        # ignore expressions after assignment in tests
+        -   path: _test\.go
+            text: only cuddled expressions if assigning variable or using from line above
+            linters: [wsl]
+        # ignore scopelint in tests for "test" variable (probably bug, maybe remove this later)
+        -   path: _test\.go
+            text: Using the variable on range scope `test` in function literal
+            linters: [scopelint]
+        # ignore goerr113 dynamic errors definition error...not sure how to approach this correctly now
+        -   text: do not define dynamic errors, use wrapped static errors instead
+            linters: [goerr113]

.goreleaser.yaml

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+archives:
+    -   files:
+            - LICENSE
+            - README.md
+            - config.toml.dist
+    -   id: binary
+        format: binary
+        name_template: snmp-proxy
+
+builds:
+    -   main: ./cmd/snmp-proxy
+        binary: snmp-proxy
+        env:
+            - CGO_ENABLED=1
+        goos:
+            - linux
+        goarch:
+            - amd64
+
+checksum:
+    name_template: 'checksums.txt'
+
+changelog:

Makefile

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+export BIN = ${PWD}/bin
+export GOBIN = $(BIN)
+
+.PHONY: build
+build:
+	for CMD in `ls cmd`; do \
+		go build ./cmd/$$CMD; \
+	done
+
+.PHONY: check
+check: lint test
+
+.PHONY: lint
+lint: $(BIN)/golangci-lint
+	$(BIN)/golangci-lint run
+
+.PHONY: fix
+fix: $(BIN)/golangci-lint
+	$(BIN)/golangci-lint run --fix
+
+.PHONY: test
+test:
+	timeout 300 go test ./...
+	timeout 300 go test --race ./...
+	timeout 300 go test --count 100 ./...
+
+.PHONY: clean
+clean:
+	rm -rf bin
+
+$(BIN)/golangci-lint:
+	curl --retry 5 -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s v1.27.0

README.md

@@ -1,2 +1,107 @@
-# go-snmp-proxy
-Proxy server for SNMP request, written in Go
+go-snmp-proxy
+=============
+
+[![Coverage Status](https://coveralls.io/repos/github/grongor/go-snmp-proxy/badge.svg)](https://coveralls.io/github/grongor/go-snmp-proxy)
+
+HTTP proxy server for SNMP requests, written in Go.
+
+Use cases
+---------
+
+- reduce time for devices with latency issues (remote locations, bad connection, ...)
+  - fetching large SNMP tree of a server in Asia from data center in US might take a long time
+- remove dependency on SNMP from your code
+  - don't want to/can't install SNMP tooling, PHP extension,... ? This solves it gracefully.
+- use HTTP authentication for your SNMP requests
+- encrypt "SNMP traffic" between the client and the server
+- bypass firewall
+- ...post your use-case via issue :-)
+
+Only SNMP versions 1 and 2c are supported. If you want support for version 3, please, send a pull request.
+
+Clients
+=======
+
+| Language | Link                               |
+|----------|------------------------------------|
+| PHP      | https://github.com/simPod/PHP-SNMP |
+
+Feel free to create an issue to include your implementation here.
+
+How it works
+------------
+
+The application provides a single HTTP endpoint `/snmp-proxy`, which accepts POST requests:
+```json
+{
+    "request_type": "getNext",
+    "host": "192.168.1.1",
+    "community": "public",
+    "oids": [
+        ".1.2.3",
+        ".4.5.6"
+    ],
+    "version": "2c",
+    "timeout": 10,
+    "retries": 3
+}
+```
+
+It will then issue SNMP requests based on the given JSON request, convert the result into JSON and send it back
+to the client. Response might look like this:
+```json
+{
+    "result": [
+        ".1.2.3.4.5",
+        123,
+        ".4.5.6.7.8",
+        "lorem"
+    ]
+}
+```
+
+Result is an array instead of a map because maps in Go aren't ordered (and overcoming this would unnecessarily
+complicated), and the order is also not guaranteed by the JSON format.
+
+If there is an error, response will be as follows:
+```json
+{
+    "error": "description of what happened"
+}
+```
+
+Some errors are "standardized" and expected:
+ - no such instance
+ - no such object
+ - end of mib
+
+The rest of the errors just describe what unexpected happened.
+
+MIBs
+----
+
+The application will try to find all installed MIBs and parse the DisplayHint information for OctetString types
+so that it knows how to format them. MIB parsing was inspired by
+[Prometheus SNMP exporter generator](https://github.com/prometheus/snmp_exporter/tree/master/generator). Thanks!
+
+In case that OID is of the type OctetString, and it isn't found in the MIBs, then we try to detect whether the string
+is printable (utf8 valid + all characters are printable). If it isn't, it's formatted as `AB C0 D5 D6...`.
+
+Metrics
+-------
+
+If you set Metrics.Listen address in the config, the application will expose Prometheus metrics on given address[:port],
+specifically on `GET /metrics`. These metrics contain all essential information about Go runtime, and a histogram
+of `POST /snmp-proxy` requests (count, durations).
+
+Shared libraries
+----------------
+
+You will have to install a shared library for the `snmp-proxy`: `libsnmp` (contained in `libsnmp-dev`).
+
+Binaries available in the [Releases](https://github.com/grongor/go-snmp-proxy/releases) will be built on the Ubuntu LTS
+and thus compatible with the version of this library available in the Ubuntu LTS (and stable Debian).
+If you that doesn't match your target system, you can:
+ - install the expected version of `libsnmp` (you will usually have the newer version, but it should be possible
+   to install older one)
+ - build the `snmp-proxy` yourself in the same environment as you expected the `snmp-proxy` to run