mirror of
https://blitiri.com.ar/repos/chasquid
synced 2025-12-19 14:57:04 +00:00
f3b01cb493
This patch adds a missing docstrings for exported identifiers, and adjust some of the existing ones to match the standard style. In some cases, the identifiers were un-exported after noticing they had no external users. Besides improving documentation, it also reduces the linter noise significantly.
107 lines
2.8 KiB
Go
107 lines
2.8 KiB
Go
package courier
|
|
|
|
import (
|
|
"bytes"
|
|
"context"
|
|
"fmt"
|
|
"os/exec"
|
|
"strings"
|
|
"syscall"
|
|
"time"
|
|
"unicode"
|
|
|
|
"blitiri.com.ar/go/chasquid/internal/envelope"
|
|
"blitiri.com.ar/go/chasquid/internal/trace"
|
|
)
|
|
|
|
var (
|
|
errTimeout = fmt.Errorf("Operation timed out")
|
|
)
|
|
|
|
// Procmail delivers local mail by executing a local binary, like procmail or
|
|
// maildrop. It is named after procmail just for reference, it works with any
|
|
// binary that:
|
|
// - Receives the email to deliver via stdin.
|
|
// - Exits with code EX_TEMPFAIL (75) for transient issues.
|
|
type Procmail struct {
|
|
Binary string // Path to the binary.
|
|
Args []string // Arguments to pass.
|
|
Timeout time.Duration // Timeout for each invocation.
|
|
}
|
|
|
|
// Deliver an email. On failures, returns an error, and whether or not it is
|
|
// permanent.
|
|
func (p *Procmail) Deliver(from string, to string, data []byte) (error, bool) {
|
|
tr := trace.New("Courier.Procmail", to)
|
|
defer tr.Finish()
|
|
|
|
// Sanitize, just in case.
|
|
from = sanitizeForProcmail(from)
|
|
to = sanitizeForProcmail(to)
|
|
|
|
tr.Debugf("%s -> %s", from, to)
|
|
|
|
// Prepare the command, replacing the necessary arguments.
|
|
replacer := strings.NewReplacer(
|
|
"%from%", from,
|
|
"%from_user%", envelope.UserOf(from),
|
|
"%from_domain%", envelope.DomainOf(from),
|
|
|
|
"%to%", to,
|
|
"%to_user%", envelope.UserOf(to),
|
|
"%to_domain%", envelope.DomainOf(to),
|
|
)
|
|
|
|
args := []string{}
|
|
for _, a := range p.Args {
|
|
args = append(args, replacer.Replace(a))
|
|
}
|
|
tr.Debugf("%s %q", p.Binary, args)
|
|
|
|
ctx, cancel := context.WithDeadline(context.Background(),
|
|
time.Now().Add(p.Timeout))
|
|
defer cancel()
|
|
cmd := exec.CommandContext(ctx, p.Binary, args...)
|
|
cmd.Stdin = bytes.NewReader(data)
|
|
|
|
output, err := cmd.CombinedOutput()
|
|
if ctx.Err() == context.DeadlineExceeded {
|
|
return tr.Error(errTimeout), false
|
|
}
|
|
|
|
if err != nil {
|
|
// Determine if the error is permanent or not.
|
|
// Default to permanent, but error code 75 is transient by general
|
|
// convention (/usr/include/sysexits.h), and commonly relied upon.
|
|
permanent := true
|
|
if exiterr, ok := err.(*exec.ExitError); ok {
|
|
if status, ok := exiterr.Sys().(syscall.WaitStatus); ok {
|
|
permanent = status.ExitStatus() != 75
|
|
}
|
|
}
|
|
err = tr.Errorf("Procmail failed: %v - %q", err, string(output))
|
|
return err, permanent
|
|
}
|
|
|
|
tr.Debugf("delivered")
|
|
return nil, false
|
|
}
|
|
|
|
// sanitizeForProcmail cleans the string, removing characters that could be
|
|
// problematic considering we will run an external command.
|
|
//
|
|
// The server does not rely on this to do substitution or proper filtering,
|
|
// that's done at a different layer; this is just for defense in depth.
|
|
func sanitizeForProcmail(s string) string {
|
|
valid := func(r rune) rune {
|
|
switch {
|
|
case unicode.IsSpace(r), unicode.IsControl(r),
|
|
strings.ContainsRune("/;\"'\\|*&$%()[]{}`!", r):
|
|
return rune(-1)
|
|
default:
|
|
return r
|
|
}
|
|
}
|
|
return strings.Map(valid, s)
|
|
}
|