preliminary git-proxy

git-proxy/go.mod

@@ -0,0 +1,3 @@
+module git.coolaj86.com/coolaj86/git-scripts/git-proxy
+
+go 1.12

git-proxy/parseargs.go

@@ -0,0 +1,59 @@
+package main
+
+import (
+	"fmt"
+	"strings"
+	"unicode"
+)
+
+const NullStr = rune(0)
+
+// ParseArgs will parse a string that contains quoted strings the same as bash does
+// (same as most other *nix shells do). This is secure in the sense that it doesn't do any
+// executing or interpeting. However, it also doesn't do any escaping, so you shouldn't pass
+// these strings to shells without escaping them.
+func ParseArgs(str string) ([]string, error) {
+	var m []string
+	var s string
+
+	str = strings.TrimSpace(str) + " "
+
+	lastQuote := NullStr
+	isSpace := false
+	for i, c := range str {
+		switch {
+		// If we're ending a quote, break out and skip this character
+		case c == lastQuote:
+			lastQuote = NullStr
+
+		// If we're in a quote, count this character
+		case lastQuote != NullStr:
+			s += string(c)
+
+		// If we encounter a quote, enter it and skip this character
+		case unicode.In(c, unicode.Quotation_Mark):
+			isSpace = false
+			lastQuote = c
+
+		// If it's a space, store the string
+		case unicode.IsSpace(c):
+			if 0 == i || isSpace {
+				continue
+			}
+			isSpace = true
+			m = append(m, s)
+			s = ""
+
+		default:
+			isSpace = false
+			s += string(c)
+		}
+
+	}
+
+	if lastQuote != NullStr {
+		return nil, fmt.Errorf("Quotes did not terminate")
+	}
+
+	return m, nil
+}

git-proxy/parseargs_test.go

@@ -0,0 +1,45 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"strings"
+	"testing"
+)
+
+func TestStrings(t *testing.T) {
+	tests := [][]string{
+		[]string{
+			`  a   'b'   ''   '"d" e' " f " ""''""''''"""" g"h"'i'jkl'mno'pqr $("dangerous dangerous danger-ous-ous-ous")`,
+			"a", "b", "", `"d" e`, " f ", "", "ghijklmnopqr", "$(dangerous dangerous danger-ous-ous-ous)",
+		},
+		[]string{
+			` arg1 arg2 '   hello    world'"'" '' " '  another hello world   ' "  `,
+			"arg1", "arg2", "   hello    world'", "", " '  another hello world   ' ",
+		},
+		[]string{
+			`arg1 arg2 '   hello    world'"'" " "" '  another hello world   ' "`,
+			"arg1", "arg2", "   hello    world'", "  '  another hello world   ' ",
+		},
+		[]string{
+			` arg1 arg2 '   hello    world'"'" "" " '  another hello world   ' "`,
+			"arg1", "arg2", "   hello    world'", "", " '  another hello world   ' ",
+		},
+		[]string{
+			`arg1 arg2 '   hello    world'"'" "" " '  another hello world   ' `,
+		},
+	}
+
+	for i := range tests {
+		strs := tests[i]
+		in := strs[0]
+		expected := strs[1:]
+
+		actual, _ := ParseArgs(in)
+		if strings.Join(actual, "#") != strings.Join(expected, "#") {
+			fmt.Printf("Expected: %#v\n", expected)
+			fmt.Printf("Actual: %#v\n", actual)
+			log.Fatal("Test failed.")
+		}
+	}
+}

git-proxy/proxy.go

@@ -0,0 +1,43 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"log"
+	"os"
+	"os/exec"
+)
+
+var ErrGitOnlyShell = errors.New("You've successfully authenticated, but this is a git-only shell")
+var gitcmds = map[string]bool{
+	"git-receive-pack":   true,
+	"git-upload-pack":    true,
+	"git-upload-archive": true,
+}
+
+func main() {
+	cmds, err := ParseArgs(os.Getenv("SSH_ORIGINAL_COMMAND"))
+	if nil != err {
+		fmt.Fprintf(os.Stderr, "%s\n", err)
+		os.Exit(1)
+	}
+
+	if len(cmds) < 2 {
+		fmt.Fprintf(os.Stderr, "%s\n", ErrGitOnlyShell)
+		os.Exit(1)
+	}
+
+	bin := cmds[0]
+	_, ok := gitcmds[bin]
+	if !ok {
+		fmt.Fprintf(os.Stderr, "%s\n", ErrGitOnlyShell)
+		os.Exit(1)
+	}
+
+	args := cmds[1:]
+	cmd := exec.Command(bin, args...)
+	cmd.Env = append(os.Environ(), "GIT_PROXY=true")
+	if err := cmd.Run(); err != nil {
+		log.Fatal(err)
+	}
+}