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all: avoid repeated default interface lookups

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On some platforms (notably macOS and iOS) we look up the default
interface to bind outgoing connections to. This is both duplicated
work and results in logspam when the default interface is not available
(i.e. when a phone has no connectivity, we log an error and thus cause
more things that we will try to upload and fail).

Fixed by passing around a netmon.Monitor to more places, so that we can
use its cached interface state.

Fixes #7850
Updates #7621

Signed-off-by: Mihai Parparita <mihai@tailscale.com>
This commit is contained in:
Mihai Parparita
2023-04-17 16:01:41 -07:00
committed by Mihai Parparita
parent 7f17e04a5a
commit 7330aa593e
50 changed files with 242 additions and 126 deletions
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16
net/dnsfallback/dnsfallback.go
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@ -23,6 +23,7 @@ import (
"time"
"tailscale.com/atomicfile"
"tailscale.com/net/netmon"
"tailscale.com/net/netns"
"tailscale.com/net/tlsdial"
"tailscale.com/net/tshttpproxy"
@ -31,13 +32,16 @@ import (
"tailscale.com/util/slicesx"
)
func Lookup(logf logger.Logf) func(ctx context.Context, host string) ([]netip.Addr, error) {
// MakeLookupFunc creates a function that can be used to resolve hostnames
// (e.g. as a LookupIPFallback from dnscache.Resolver).
// The netMon parameter is optional; if non-nil it's used to do faster interface lookups.
func MakeLookupFunc(logf logger.Logf, netMon *netmon.Monitor) func(ctx context.Context, host string) ([]netip.Addr, error) {
return func(ctx context.Context, host string) ([]netip.Addr, error) {
return lookup(ctx, host, logf)
return lookup(ctx, host, logf, netMon)
}
}
func lookup(ctx context.Context, host string, logf logger.Logf) ([]netip.Addr, error) {
func lookup(ctx context.Context, host string, logf logger.Logf, netMon *netmon.Monitor) ([]netip.Addr, error) {
if ip, err := netip.ParseAddr(host); err == nil && ip.IsValid() {
return []netip.Addr{ip}, nil
}
@ -85,7 +89,7 @@ func lookup(ctx context.Context, host string, logf logger.Logf) ([]netip.Addr, e
logf("trying bootstrapDNS(%q, %q) for %q ...", cand.dnsName, cand.ip, host)
ctx, cancel := context.WithTimeout(ctx, 3*time.Second)
defer cancel()
dm, err := bootstrapDNSMap(ctx, cand.dnsName, cand.ip, host, logf)
dm, err := bootstrapDNSMap(ctx, cand.dnsName, cand.ip, host, logf, netMon)
if err != nil {
logf("bootstrapDNS(%q, %q) for %q error: %v", cand.dnsName, cand.ip, host, err)
continue
@ -104,8 +108,8 @@ func lookup(ctx context.Context, host string, logf logger.Logf) ([]netip.Addr, e
// serverName and serverIP of are, say, "derpN.tailscale.com".
// queryName is the name being sought (e.g. "controlplane.tailscale.com"), passed as hint.
func bootstrapDNSMap(ctx context.Context, serverName string, serverIP netip.Addr, queryName string, logf logger.Logf) (dnsMap, error) {
dialer := netns.NewDialer(logf)
func bootstrapDNSMap(ctx context.Context, serverName string, serverIP netip.Addr, queryName string, logf logger.Logf, netMon *netmon.Monitor) (dnsMap, error) {
dialer := netns.NewDialer(logf, netMon)
tr := http.DefaultTransport.(*http.Transport).Clone()
tr.Proxy = tshttpproxy.ProxyFromEnvironment
tr.DialContext = func(ctx context.Context, netw, addr string) (net.Conn, error) {