Initial commit

.builds/amd64_freebsd.yml

@@ -0,0 +1,14 @@
+arch: amd64
+environment:
+  PROJECT_NAME: 'sshtargate'
+  CGO_ENABLED: '1'
+  GO111MODULE: 'on'
+image: freebsd/latest
+packages:
+  - go
+sources:
+  - https://git.sr.ht/~tslocum/sshtargate
+tasks:
+  - test: |
+      cd $PROJECT_NAME
+      go test ./...

.builds/amd64_linux_alpine.yml

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+arch: x86_64
+environment:
+  PROJECT_NAME: 'sshtargate'
+  CGO_ENABLED: '1'
+  GO111MODULE: 'on'
+image: alpine/edge
+packages:
+  - go
+sources:
+  - https://git.sr.ht/~tslocum/sshtargate
+tasks:
+  - test: |
+      cd $PROJECT_NAME
+      go test ./...

.gitignore

@@ -0,0 +1,5 @@
+.idea/
+dist/
+vendor/
+sshtargate
+*.sh

CHANGELOG

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+0.1.0:
+- Initial release

CONFIGURATION.md

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+This document explains how to configure sshtargate.
+
+# Configuration
+
+Specify the path to a configuration file with ```--config``` or create a file
+at the default path of ```~/.config/sshtargate/config.yaml```.
+
+Define one or more **portals** by name/label with the following options:
+
+- **command** - Command to execute
+- **host** - One or more addresses to listen for connections
+
+# Example config.yaml
+
+```
+portals:
+  date and time:
+    command: date
+    host:
+      - localhost:19001
+  uname:
+    command: uname -a
+    host:
+      - localhost:19002
+  process list:
+    command: ps -aux
+    host:
+      - localhost:19003
+  system monitor:
+    command: htop
+    host:
+      - localhost:19004
+```

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2020 Trevor Slocum <trevor@rocketnine.space>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -0,0 +1,28 @@
+# sshtargate
+[![GoDoc](https://godoc.org/git.sr.ht/~tslocum/sshtargate?status.svg)](https://godoc.org/git.sr.ht/~tslocum/sshtargate)
+[![builds.sr.ht status](https://builds.sr.ht/~tslocum/sshtargate.svg)](https://builds.sr.ht/~tslocum/sshtargate)
+[![Donate](https://img.shields.io/liberapay/receives/rocketnine.space.svg?logo=liberapay)](https://liberapay.com/rocketnine.space)
+
+Host SSH portals to applications
+
+## Install
+
+Choose one of the following methods:
+
+### Download
+
+[**Download sshtargate**](https://sshtargate.rocketnine.space/download/?sort=name&order=desc)
+
+### Compile
+
+```
+GO111MODULE=on go get git.sr.ht/~tslocum/sshtargate
+```
+
+## Configure
+
+See [CONFIGURATION.md](https://man.sr.ht/~tslocum/sshtargate/CONFIGURATION.md)
+
+## Support
+
+Please share issues/suggestions [here](https://todo.sr.ht/~tslocum/sshtargate).

config.go

@@ -0,0 +1,38 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+
+	"gopkg.in/yaml.v2"
+)
+
+type PortalConfig struct {
+	Command string
+	Host    []string `yaml:",flow"`
+}
+
+type Config struct {
+	Portals map[string]*PortalConfig
+}
+
+var config = &Config{}
+
+func readConfig(configPath string) error {
+	configData, err := ioutil.ReadFile(configPath)
+	if err != nil {
+		return fmt.Errorf("failed to read file: %s", err)
+	}
+
+	err = yaml.Unmarshal(configData, config)
+	if err != nil {
+		return fmt.Errorf("failed to parse file: %s", err)
+	}
+
+	if len(config.Portals) == 0 {
+		log.Println("Warning: No portals are defined")
+	}
+
+	return nil
+}

go.mod

@@ -0,0 +1,12 @@
+module git.sr.ht/~tslocum/sshtargate
+
+go 1.13
+
+require (
+	github.com/anmitsu/go-shlex v0.0.0-20161002113705-648efa622239
+	github.com/creack/pty v1.1.9
+	github.com/gliderlabs/ssh v0.2.2
+	golang.org/x/crypto v0.0.0-20191227163750-53104e6ec876
+	golang.org/x/sys v0.0.0-20200103143344-a1369afcdac7 // indirect
+	gopkg.in/yaml.v2 v2.2.7
+)

go.sum

@@ -0,0 +1,20 @@
+github.com/anmitsu/go-shlex v0.0.0-20161002113705-648efa622239 h1:kFOfPq6dUM1hTo4JG6LR5AXSUEsOjtdm0kw0FtQtMJA=
+github.com/anmitsu/go-shlex v0.0.0-20161002113705-648efa622239/go.mod h1:2FmKhYUyUczH0OGQWaF5ceTx0UBShxjsH6f8oGKYe2c=
+github.com/creack/pty v1.1.9 h1:uDmaGzcdjhF4i/plgjmEsriH11Y0o7RKapEf/LDaM3w=
+github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
+github.com/flynn/go-shlex v0.0.0-20150515145356-3f9db97f8568 h1:BHsljHzVlRcyQhjrss6TZTdY2VfCqZPbv5k3iBFa2ZQ=
+github.com/flynn/go-shlex v0.0.0-20150515145356-3f9db97f8568/go.mod h1:xEzjJPgXI435gkrCt3MPfRiAkVrwSbHsst4LCFVfpJc=
+github.com/gliderlabs/ssh v0.2.2 h1:6zsha5zo/TWhRhwqCD3+EarCAgZ2yN28ipRnGPnwkI0=
+github.com/gliderlabs/ssh v0.2.2/go.mod h1:U7qILu1NlMHj9FlMhZLlkCdDnU1DBEAqr0aevW3Awn0=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20191227163750-53104e6ec876 h1:sKJQZMuxjOAR/Uo2LBfU90onWEf1dF4C+0hPJCc9Mpc=
+golang.org/x/crypto v0.0.0-20191227163750-53104e6ec876/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200103143344-a1369afcdac7 h1:/W9OPMnnpmFXHYkcp2rQsbFUbRlRzfECQjmAFiOyHE8=
+golang.org/x/sys v0.0.0-20200103143344-a1369afcdac7/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.7 h1:VUgggvou5XRW9mHwD/yXxIYSMtY0zoKQf/v226p2nyo=
+gopkg.in/yaml.v2 v2.2.7/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

goreleaser.yml

@@ -0,0 +1,33 @@
+project_name: sshtargate
+
+builds:
+  -
+    id: sshtargate
+    binary: sshtargate
+    env:
+      - CGO_ENABLED=0
+    ldflags:
+      - -s -w -X git.sr.ht/~tslocum/sshtargate/version={{.Version}}
+    goos:
+      - darwin
+      - freebsd
+      - linux
+    goarch:
+      - 386
+      - amd64
+archives:
+  -
+    id: sshtargate
+    builds:
+      - sshtargate
+    replacements:
+      386: i386
+    format_overrides:
+      - goos: windows
+        format: zip
+    files:
+      - ./*.md
+      - CHANGELOG
+      - LICENSE
+checksum:
+  name_template: 'checksums.txt'

main.go

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+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"os"
+	"os/signal"
+	"path"
+	"strings"
+	"sync"
+	"syscall"
+
+	"git.sr.ht/~tslocum/sshtargate/pkg/gate"
+	"github.com/anmitsu/go-shlex"
+)
+
+const (
+	version = "0.0.0"
+
+	versionInfo = `sshtargate - Host SSH portals to applications - v` + version + `
+https://git.sr.ht/~tslocum/sshtargate
+The MIT License (MIT)
+Copyright (c) 2020 Trevor Slocum <trevor@rocketnine.space>
+`
+)
+
+var (
+	printVersionInfo bool
+	configPath       string
+
+	portals     []*gate.Portal
+	portalsLock = new(sync.Mutex)
+
+	done = make(chan bool)
+)
+
+func main() {
+	flag.BoolVar(&printVersionInfo, "version", false, "print version information and exit")
+	flag.StringVar(&configPath, "config", "", "path to configuration file")
+	flag.Parse()
+
+	if printVersionInfo {
+		fmt.Print(versionInfo)
+		return
+	}
+
+	// TODO: Allow portals to be specified via arguments
+
+	// TODO: Catch SIGHUP
+	sigc := make(chan os.Signal, 1)
+	signal.Notify(sigc,
+		syscall.SIGINT,
+		syscall.SIGTERM)
+	go func() {
+		<-sigc
+
+		done <- true
+	}()
+
+	log.Println("Initializing sshtargate...")
+
+	if configPath == "" {
+		homedir, err := os.UserHomeDir()
+		if err == nil && homedir != "" {
+			configPath = path.Join(homedir, ".config", "sshtargate", "config.yaml")
+		}
+	}
+
+	err := readConfig(configPath)
+	if err != nil {
+		log.Fatalf("failed to read configuration file %s: %s", configPath, err)
+	}
+
+	for pname, pcfg := range config.Portals {
+		cs, err := shlex.Split(pcfg.Command, true)
+		if err != nil {
+			log.Fatalf("failed to split command %s", pcfg.Command)
+		}
+
+		pname, pcfg := pname, pcfg // Capture
+		go func() {
+			wg := new(sync.WaitGroup)
+
+			for _, address := range pcfg.Host {
+				wg.Add(1)
+				address := address // Capture
+
+				go func() {
+					p, err := gate.NewPortal(pname, address, cs)
+					if err != nil {
+						log.Fatalf("failed to start portal %s on %s: %s", pname, address, err)
+					}
+
+					portalsLock.Lock()
+					portals = append(portals, p)
+					portalsLock.Unlock()
+
+					wg.Done()
+				}()
+			}
+
+			wg.Wait()
+			log.Printf("Opened portal %s on %s to %s", pname, strings.Join(pcfg.Host, ","), pcfg.Command)
+		}()
+	}
+
+	<-done
+
+	portalsLock.Lock()
+	for _, p := range portals {
+		p.Shutdown()
+	}
+	portalsLock.Unlock()
+}

pkg/gate/portal.go

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+package gate
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+	"path"
+	"syscall"
+	"time"
+	"unsafe"
+
+	"github.com/creack/pty"
+	"github.com/gliderlabs/ssh"
+	gossh "golang.org/x/crypto/ssh"
+)
+
+const (
+	ListenTimeout = 1 * time.Second
+	IdleTimeout   = 1 * time.Minute
+)
+
+type Portal struct {
+	Name    string
+	Address string
+	Command []string
+	Server  *ssh.Server
+}
+
+func setWinsize(f *os.File, w, h int) {
+	syscall.Syscall(syscall.SYS_IOCTL, f.Fd(), uintptr(syscall.TIOCSWINSZ),
+		uintptr(unsafe.Pointer(&struct{ h, w, x, y uint16 }{uint16(h), uint16(w), 0, 0})))
+}
+
+func NewPortal(name string, address string, command []string) (*Portal, error) {
+	if address == "" {
+		return nil, errors.New("no address supplied")
+	} else if command == nil || command[0] == "" {
+		return nil, errors.New("no command supplied")
+	}
+
+	server := &ssh.Server{
+		Addr:        address,
+		IdleTimeout: IdleTimeout,
+		Handler: func(sshSession ssh.Session) {
+			ptyReq, winCh, isPty := sshSession.Pty()
+			if !isPty {
+				io.WriteString(sshSession, "failed to start command: non-interactive terminals are not supported\n")
+				sshSession.Exit(1)
+				return
+			}
+
+			cmdCtx, cancelCmd := context.WithCancel(sshSession.Context())
+			defer cancelCmd()
+
+			var args []string
+			if len(command) > 1 {
+				args = command[1:]
+			}
+
+			cmd := exec.CommandContext(cmdCtx, command[0], args...)
+			cmd.Env = append(cmd.Env, fmt.Sprintf("TERM=%s", ptyReq.Term))
+
+			f, err := pty.Start(cmd)
+			if err != nil {
+				io.WriteString(sshSession, fmt.Sprintf("failed to start command: failed to initialize pseudo-terminal: %s\n", err))
+				sshSession.Exit(1)
+				return
+			}
+			defer f.Close()
+
+			go func() {
+				for win := range winCh {
+					setWinsize(f, win.Width, win.Height)
+				}
+			}()
+
+			go func() {
+				io.Copy(f, sshSession)
+			}()
+			io.Copy(sshSession, f)
+
+			cmd.Wait()
+		},
+		PtyCallback: func(ctx ssh.Context, pty ssh.Pty) bool {
+			return true
+		},
+		PublicKeyHandler: func(ctx ssh.Context, key ssh.PublicKey) bool {
+			return true
+		},
+		PasswordHandler: func(ctx ssh.Context, password string) bool {
+			return true
+		},
+		KeyboardInteractiveHandler: func(ctx ssh.Context, challenger gossh.KeyboardInteractiveChallenge) bool {
+			return true
+		},
+	}
+
+	homeDir, err := os.UserHomeDir()
+	if err != nil {
+		return nil, fmt.Errorf("failed to retrieve user home dir: %s", err)
+	}
+
+	err = server.SetOption(ssh.HostKeyFile(path.Join(homeDir, ".ssh", "id_rsa")))
+	if err != nil {
+		return nil, fmt.Errorf("failed to set host key file: %s", err)
+	}
+
+	t := time.NewTimer(ListenTimeout)
+	errs := make(chan error)
+	go func() {
+		err := server.ListenAndServe()
+		if err != nil {
+			errs <- fmt.Errorf("failed to start SSH server: %s", err)
+		}
+	}()
+	select {
+	case err = <-errs:
+		return nil, err
+	case <-t.C:
+		// Server started
+	}
+
+	p := Portal{Name: name, Address: address, Command: command, Server: server}
+
+	return &p, nil
+}
+
+func (p *Portal) Shutdown() {
+	p.Server.Close()
+}