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https://blitiri.com.ar/repos/chasquid
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362ef6f6d0
This patch introduces an "envelope" package which, for now, provides simple utilities for getting the user and domain of an address. It also changes the couriers to use it (but other implementations remain, will be moved over in subsequent patches).
107 lines
2.5 KiB
Go
107 lines
2.5 KiB
Go
package courier
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import (
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"bytes"
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"fmt"
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"os/exec"
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"strings"
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"time"
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"unicode"
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"blitiri.com.ar/go/chasquid/internal/envelope"
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"blitiri.com.ar/go/chasquid/internal/trace"
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)
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var (
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// Location of the procmail binary, and arguments to use.
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// The string "%user%" will be replaced with the local user.
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// TODO: Make these a part of the courier instance itself? Why do they
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// have to be global?
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MailDeliveryAgentBin = "procmail"
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MailDeliveryAgentArgs = []string{"-d", "%user%"}
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// Give procmail 1m to deliver mail.
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procmailTimeout = 1 * time.Minute
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)
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var (
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timeoutError = fmt.Errorf("Operation timed out")
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)
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// Procmail delivers local mail via procmail.
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type Procmail struct {
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}
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func (p *Procmail) Deliver(from string, to string, data []byte) error {
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tr := trace.New("Procmail", "Deliver")
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defer tr.Finish()
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// Get the user, and sanitize to be extra paranoid.
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user := sanitizeForProcmail(envelope.UserOf(to))
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domain := sanitizeForProcmail(envelope.DomainOf(to))
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tr.LazyPrintf("%s -> %s (%s @ %s)", from, user, to, domain)
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// Prepare the command, replacing the necessary arguments.
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replacer := strings.NewReplacer(
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"%user%", user,
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"%domain%", domain)
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args := []string{}
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for _, a := range MailDeliveryAgentArgs {
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args = append(args, replacer.Replace(a))
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}
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cmd := exec.Command(MailDeliveryAgentBin, args...)
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cmdStdin, err := cmd.StdinPipe()
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if err != nil {
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return tr.Errorf("StdinPipe: %v", err)
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}
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output := &bytes.Buffer{}
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cmd.Stdout = output
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cmd.Stderr = output
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err = cmd.Start()
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if err != nil {
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return tr.Errorf("Error starting procmail: %v", err)
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}
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_, err = bytes.NewBuffer(data).WriteTo(cmdStdin)
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if err != nil {
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return tr.Errorf("Error sending data to procmail: %v", err)
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}
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cmdStdin.Close()
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timer := time.AfterFunc(procmailTimeout, func() {
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cmd.Process.Kill()
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})
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err = cmd.Wait()
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timedOut := !timer.Stop()
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if timedOut {
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return tr.Error(timeoutError)
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}
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if err != nil {
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return tr.Errorf("Procmail failed: %v - %q", err, output.String())
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}
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return nil
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}
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// sanitizeForProcmail cleans the string, removing characters that could be
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// problematic considering we will run an external command.
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//
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// The server does not rely on this to do substitution or proper filtering,
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// that's done at a different layer; this is just for defense in depth.
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func sanitizeForProcmail(s string) string {
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valid := func(r rune) rune {
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switch {
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case unicode.IsSpace(r), unicode.IsControl(r),
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strings.ContainsRune("/;\"'\\|*&$%()[]{}`!", r):
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return rune(-1)
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default:
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return r
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}
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}
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return strings.Map(valid, s)
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}
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