mirror of
https://blitiri.com.ar/repos/chasquid
synced 2025-12-19 14:57:04 +00:00
5faffbbfe3
The way the procmail courier runs the command is unnecessary convoluted, this patch simplifies it by using the corresponding standard tools.
104 lines
2.5 KiB
Go
104 lines
2.5 KiB
Go
package courier
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import (
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"bytes"
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"context"
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"fmt"
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"os/exec"
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"strings"
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"syscall"
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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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errTimeout = 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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Binary string // Path to the binary.
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Args []string // Arguments to pass.
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Timeout time.Duration // Timeout for each invocation.
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}
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func (p *Procmail) Deliver(from string, to string, data []byte) (error, bool) {
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tr := trace.New("Procmail.Courier", to)
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defer tr.Finish()
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// Sanitize, just in case.
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from = sanitizeForProcmail(from)
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to = sanitizeForProcmail(to)
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tr.Debugf("%s -> %s", from, to)
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// Prepare the command, replacing the necessary arguments.
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replacer := strings.NewReplacer(
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"%from%", from,
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"%from_user%", envelope.UserOf(from),
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"%from_domain%", envelope.DomainOf(from),
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"%to%", to,
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"%to_user%", envelope.UserOf(to),
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"%to_domain%", envelope.DomainOf(to),
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)
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args := []string{}
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for _, a := range p.Args {
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args = append(args, replacer.Replace(a))
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}
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ctx, cancel := context.WithDeadline(context.Background(),
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time.Now().Add(p.Timeout))
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defer cancel()
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cmd := exec.CommandContext(ctx, p.Binary, args...)
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cmd.Stdin = bytes.NewReader(data)
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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.Run()
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if ctx.Err() == context.DeadlineExceeded {
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return tr.Error(errTimeout), false
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}
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if err != nil {
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// Determine if the error is permanent or not.
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// Default to permanent, but error code 75 is transient by general
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// convention (/usr/include/sysexits.h), and commonly relied upon.
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permanent := true
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if exiterr, ok := err.(*exec.ExitError); ok {
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if status, ok := exiterr.Sys().(syscall.WaitStatus); ok {
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permanent = status.ExitStatus() != 75
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}
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}
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err = tr.Errorf("Procmail failed: %v - %q", err, output.String())
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return err, permanent
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}
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tr.Debugf("delivered")
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return nil, false
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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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