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m13253m13253
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Merge pull request #185 from shahradelahi/feature/bind-to-interface
2 parents 602b3d6 + 06e3d67 commit 82c5f0d

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3 files changed

+163
-6
lines changed

3 files changed

+163
-6
lines changed

‎doh-client/client.go‎

Lines changed: 157 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -90,6 +90,29 @@ func NewClient(conf *config.Config) (c *Client, err error) {
9090
Net: "tcp",
9191
Timeout: time.Duration(conf.Other.Timeout) * time.Second,
9292
}
93+
94+
if c.conf.Other.Interface != "" {
95+
localV4, localV6, err := c.getInterfaceIPs()
96+
if err != nil {
97+
return nil, fmt.Errorf("failed to get interface IPs for %s: %v", c.conf.Other.Interface, err)
98+
}
99+
var localAddr net.IP
100+
if localV4 != nil {
101+
localAddr = localV4
102+
} else {
103+
localAddr = localV6
104+
}
105+
106+
c.udpClient.Dialer = &net.Dialer{
107+
Timeout: time.Duration(conf.Other.Timeout) * time.Second,
108+
LocalAddr: &net.UDPAddr{IP: localAddr},
109+
}
110+
c.tcpClient.Dialer = &net.Dialer{
111+
Timeout: time.Duration(conf.Other.Timeout) * time.Second,
112+
LocalAddr: &net.TCPAddr{IP: localAddr},
113+
}
114+
}
115+
93116
for _, addr := range conf.Listen {
94117
c.udpServers = append(c.udpServers, &dns.Server{
95118
Addr: addr,
@@ -120,6 +143,38 @@ func NewClient(conf *config.Config) (c *Client, err error) {
120143
PreferGo: true,
121144
Dial: func(ctx context.Context, network, address string) (net.Conn, error) {
122145
var d net.Dialer
146+
if c.conf.Other.Interface != "" {
147+
localV4, localV6, err := c.getInterfaceIPs()
148+
if err != nil {
149+
log.Printf("Bootstrap dial warning: %v", err)
150+
} else {
151+
numServers := len(c.bootstrap)
152+
bootstrap := c.bootstrap[rand.Intn(numServers)]
153+
host, _, _ := net.SplitHostPort(bootstrap)
154+
ip := net.ParseIP(host)
155+
if ip != nil {
156+
if ip.To4() != nil {
157+
if localV4 != nil {
158+
if strings.HasPrefix(network, "udp") {
159+
d.LocalAddr = &net.UDPAddr{IP: localV4}
160+
} else {
161+
d.LocalAddr = &net.TCPAddr{IP: localV4}
162+
}
163+
}
164+
} else {
165+
if localV6 != nil {
166+
if strings.HasPrefix(network, "udp") {
167+
d.LocalAddr = &net.UDPAddr{IP: localV6}
168+
} else {
169+
d.LocalAddr = &net.TCPAddr{IP: localV6}
170+
}
171+
}
172+
}
173+
}
174+
conn, err := d.DialContext(ctx, network, bootstrap)
175+
return conn, err
176+
}
177+
}
123178
numServers := len(c.bootstrap)
124179
bootstrap := c.bootstrap[rand.Intn(numServers)]
125180
conn, err := d.DialContext(ctx, network, bootstrap)
@@ -235,14 +290,72 @@ func (c *Client) newHTTPClient() error {
235290
if c.httpTransport != nil {
236291
c.httpTransport.CloseIdleConnections()
237292
}
238-
dialer := &net.Dialer{
293+
294+
localV4, localV6, err := c.getInterfaceIPs()
295+
if err != nil {
296+
log.Printf("Interface binding error: %v", err)
297+
return err
298+
}
299+
300+
baseDialer := &net.Dialer{
239301
Timeout: time.Duration(c.conf.Other.Timeout) * time.Second,
240302
KeepAlive: 30 * time.Second,
241-
// DualStack: true,
242-
Resolver: c.bootstrapResolver,
303+
Resolver: c.bootstrapResolver,
243304
}
305+
244306
c.httpTransport = &http.Transport{
245-
DialContext: dialer.DialContext,
307+
DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
308+
if c.conf.Other.Interface == "" {
309+
return baseDialer.DialContext(ctx, network, addr)
310+
}
311+
312+
if network == "tcp4" && localV4 != nil {
313+
d := *baseDialer
314+
d.LocalAddr = &net.TCPAddr{IP: localV4}
315+
return d.DialContext(ctx, network, addr)
316+
}
317+
if network == "tcp6" && localV6 != nil {
318+
d := *baseDialer
319+
d.LocalAddr = &net.TCPAddr{IP: localV6}
320+
return d.DialContext(ctx, network, addr)
321+
}
322+
323+
// Manual Dual-Stack: Resolve host and try compatible families sequentially
324+
host, port, _ := net.SplitHostPort(addr)
325+
ips, err := c.bootstrapResolver.LookupIPAddr(ctx, host)
326+
if err != nil {
327+
return nil, err
328+
}
329+
330+
var lastErr error
331+
for _, ip := range ips {
332+
d := *baseDialer
333+
targetAddr := net.JoinHostPort(ip.String(), port)
334+
335+
if ip.IP.To4() != nil {
336+
if localV4 == nil {
337+
continue
338+
}
339+
d.LocalAddr = &net.TCPAddr{IP: localV4}
340+
} else {
341+
if localV6 == nil {
342+
continue
343+
}
344+
d.LocalAddr = &net.TCPAddr{IP: localV6}
345+
}
346+
347+
conn, err := d.DialContext(ctx, "tcp", targetAddr)
348+
if err == nil {
349+
return conn, nil
350+
}
351+
lastErr = err
352+
}
353+
354+
if lastErr != nil {
355+
return nil, lastErr
356+
}
357+
return nil, fmt.Errorf("connection to %s failed: no matching local/remote IP families on interface %s", addr, c.conf.Other.Interface)
358+
},
246359
ExpectContinueTimeout: 1 * time.Second,
247360
IdleConnTimeout: 90 * time.Second,
248361
MaxIdleConns: 100,
@@ -251,15 +364,18 @@ func (c *Client) newHTTPClient() error {
251364
TLSHandshakeTimeout: time.Duration(c.conf.Other.Timeout) * time.Second,
252365
TLSClientConfig: &tls.Config{InsecureSkipVerify: c.conf.Other.TLSInsecureSkipVerify},
253366
}
367+
254368
if c.conf.Other.NoIPv6 {
369+
originalDial := c.httpTransport.DialContext
255370
c.httpTransport.DialContext = func(ctx context.Context, network, address string) (net.Conn, error) {
256371
if strings.HasPrefix(network, "tcp") {
257372
network = "tcp4"
258373
}
259-
return dialer.DialContext(ctx, network, address)
374+
return originalDial(ctx, network, address)
260375
}
261376
}
262-
err := http2.ConfigureTransport(c.httpTransport)
377+
378+
err = http2.ConfigureTransport(c.httpTransport)
263379
if err != nil {
264380
return err
265381
}
@@ -485,3 +601,38 @@ func (c *Client) findClientIP(w dns.ResponseWriter, r *dns.Msg) (ednsClientAddre
485601
}
486602
return
487603
}
604+
605+
// getInterfaceIPs returns the first valid IPv4 and IPv6 addresses found on the interface
606+
func (c *Client) getInterfaceIPs() (v4, v6 net.IP, err error) {
607+
if c.conf.Other.Interface == "" {
608+
return nil, nil, nil
609+
}
610+
ifi, err := net.InterfaceByName(c.conf.Other.Interface)
611+
if err != nil {
612+
return nil, nil, err
613+
}
614+
addrs, err := ifi.Addrs()
615+
if err != nil {
616+
return nil, nil, err
617+
}
618+
619+
for _, addr := range addrs {
620+
ip, _, err := net.ParseCIDR(addr.String())
621+
if err != nil {
622+
continue
623+
}
624+
if ip4 := ip.To4(); ip4 != nil {
625+
if v4 == nil {
626+
v4 = ip4
627+
}
628+
} else {
629+
if v6 == nil && !c.conf.Other.NoIPv6 {
630+
v6 = ip
631+
}
632+
}
633+
}
634+
if v4 == nil && v6 == nil {
635+
return nil, nil, fmt.Errorf("no valid IP addresses found on interface %s", c.conf.Other.Interface)
636+
}
637+
return v4, v6, nil
638+
}

‎doh-client/config/config.go‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -50,6 +50,7 @@ type others struct {
5050
Bootstrap []string `toml:"bootstrap"`
5151
Passthrough []string `toml:"passthrough"`
5252
Timeout uint `toml:"timeout"`
53+
Interface string `toml:"interface"`
5354
NoCookies bool `toml:"no_cookies"`
5455
NoECS bool `toml:"no_ecs"`
5556
NoIPv6 bool `toml:"no_ipv6"`

‎doh-client/doh-client.conf‎

Lines changed: 5 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -97,6 +97,11 @@ passthrough = [
9797
# Timeout for upstream request in seconds
9898
timeout = 30
9999

100+
# Interface to bind to for outgoing connections.
101+
# If empty, the system default route is used (usually eth0 or wlan0).
102+
# Example: "eth1", "wlan0"
103+
interface = ""
104+
100105
# Disable HTTP Cookies
101106
#
102107
# Cookies may be useful if your upstream resolver is protected by some

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