mirror of
https://github.com/warmbly/warmbly.git
synced 2026-08-19 00:01:14 +00:00
Matthew Meszaros
b71deb37a6
Tiny helper that builds a *net.Dialer (and tls.Dialer wrapper) with an optional LocalAddr. Used by the SMTP and IMAP clients so a worker on a multi-IP box can bind outbound TCP to a specific source IP. Bind IP comes from an explicit *net.TCPAddr on the client, or falls back to the WORKER_BIND_IP env var, or finally to the OS default route. The env-var path is cached once via sync.Once. 4 tests cover explicit bind, nil-passthrough, tls.Dialer composition, and timeout sanity.
65 lines
1.5 KiB
Go
65 lines
1.5 KiB
Go
// Package netbind constructs outbound dialers with an optional source IP.
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//
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// Use cases:
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// - Self-hoster on a single-IP VPS: no env var set, default route is used.
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// - Hosted Warmbly on a multi-IP box: WORKER_BIND_IP set per process so
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// SMTP/IMAP/HTTPS egress leaves from the assigned IP.
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// - Multi-egress per process (future): callers pass an explicit *net.TCPAddr
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// overriding the env-var fallback.
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package netbind
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import (
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"crypto/tls"
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"net"
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"os"
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"sync"
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"time"
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)
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const (
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envBindIP = "WORKER_BIND_IP"
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defaultTimeout = 10 * time.Second
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)
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var (
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envOnce sync.Once
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envIP *net.TCPAddr
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)
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// FromEnv returns the *net.TCPAddr derived from the WORKER_BIND_IP env var, or
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// nil if unset/invalid. The lookup is cached for the lifetime of the process.
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func FromEnv() *net.TCPAddr {
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envOnce.Do(func() {
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raw := os.Getenv(envBindIP)
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if raw == "" {
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return
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}
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ip := net.ParseIP(raw)
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if ip == nil {
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return
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}
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envIP = &net.TCPAddr{IP: ip}
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})
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return envIP
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}
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// Dialer returns a *net.Dialer bound to the given local address. If local is
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// nil, the env var is consulted. If still unset, the OS default route is used.
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func Dialer(local *net.TCPAddr) *net.Dialer {
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if local == nil {
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local = FromEnv()
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}
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return &net.Dialer{
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Timeout: defaultTimeout,
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LocalAddr: local,
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}
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}
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// TLSDialer mirrors Dialer for TLS connections (IMAP, HTTPS).
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func TLSDialer(local *net.TCPAddr, cfg *tls.Config) *tls.Dialer {
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return &tls.Dialer{
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NetDialer: Dialer(local),
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Config: cfg,
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}
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}
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