Really fix DNS

The previous patch was merged against a different version of Go, plus had bugs.
Now given I am able to build stuff, this seems to do the right job.

make-go.bash

@@ -60,14 +60,12 @@ mkdir -p "$GOROOT_FINAL"
 
 pushd ext/golang/go/src
 
+git reset --hard HEAD
+
 # Apply patches to Golang
 for PATCH in $MYDIR/patches/golang/all/*.patch; do
-    if ! patch -R -p1 --dry-run <$PATCH &>/dev/null; then
     echo "Applying $PATCH"
     patch -p1 <$PATCH
-    else
-        echo "Patch $PATCH already applied"
-    fi
 done
 
 set +e

patches/golang/all/dns.patch

@@ -1,8 +1,25 @@
+diff --git a/net/dnsclient_unix.go b/net/dnsclient_unix.go
+index 17188f0..15a1663 100644
+--- a/net/dnsclient_unix.go
++++ b/net/dnsclient_unix.go
+@@ -279,12 +279,6 @@ func (conf *resolverConfig) tryUpdate(name string) {
+ 			return
+ 		}
+ 		conf.modTime = fi.ModTime()
+-	} else {
+-		// If modTime wasn't set prior, assume nothing has changed.
+-		if conf.modTime.IsZero() {
+-			return
+-		}
+-		conf.modTime = time.Time{}
+ 	}
+ 
+ 	dnsConf := dnsReadConfig(name)
 diff --git a/net/dnsconfig_unix.go b/net/dnsconfig_unix.go
-index 6073fdb..9df3cec 100644
+index 6073fdb..bd6ca41 100644
 --- a/net/dnsconfig_unix.go
 +++ b/net/dnsconfig_unix.go
-@@ -8,18 +8,57 @@
+@@ -8,7 +8,53 @@
  
  package net
  
@@ -11,97 +28,62 @@ index 6073fdb..9df3cec 100644
 +	"fmt"
 +	"os/exec"
 +	"strings"
-+	"sync"
-+	"time"
 +)
 +
-+var (
++var currentNS []string
-+	logOnce sync.Once
-+)
 +
 +func getDefaultNS() []string {
 +	var servers []string
-+	for _, prop := range []string{"net.dns", "net.dns1", "net.dns2", "net.dns3", "net.dns4"} {
++	for _, prop := range []string{"net.dns1", "net.dns2"} {
 +		cmd := exec.Command("getprop", prop)
-+		if cmd.Run() == nil {
 +		outputBytes, err := cmd.Output()
 +		if err != nil {
 +			continue
 +		}
-+
 +		output := strings.Trim(string(outputBytes), "\n")
 +		if ParseIP(output) != nil {
 +			servers = append(servers, output)
 +		}
 +	}
-+	}
 +
-+	if servers == nil {
++	if len(servers) == 0 {
 +		servers = []string{"8.8.8.8", "8.8.4.4", "4.2.2.1"}
 +	}
 +
-+	logOnce.Do(func() {
++	if !slicesEqual(currentNS, servers) {
-+		fmt.Println("Using the following DNS servers", servers)
++		fmt.Println("Using DNS servers:", servers)
-+	})
++		currentNS = servers
++	}
 +
-+	return servers
++	return currentNS
++}
++
++func slicesEqual(a, b []string) bool {
++	if len(a) != len(b) {
++		return false
++	}
++
++	for i := range a {
++		if a[i] != b[i] {
++			return false
++		}
++	}
++
++	return true
 +}
  
  type dnsConfig struct {
--	servers    []string // servers to use
+ 	servers    []string // servers to use
--	search     []string // suffixes to append to local name
+@@ -33,7 +79,7 @@ func dnsReadConfig(filename string) *dnsConfig {
--	ndots      int      // number of dots in name to trigger absolute lookup
--	timeout    int      // seconds before giving up on packet
--	attempts   int      // lost packets before giving up on server
--	rotate     bool     // round robin among servers
--	unknownOpt bool     // anything unknown was encountered
--	lookup     []string // OpenBSD top-level database "lookup" order
--	err        error    // any error that occurs during open of resolv.conf
-+	servers    []string  // servers to use
-+	search     []string  // suffixes to append to local name
-+	ndots      int       // number of dots in name to trigger absolute lookup
-+	timeout    int       // seconds before giving up on packet
-+	attempts   int       // lost packets before giving up on server
-+	rotate     bool      // round robin among servers
-+	unknownOpt bool      // anything unknown was encountered
-+	lookup     []string  // OpenBSD top-level database "lookup" order
-+	err        error     // any error that occurs during open of resolv.conf
-+	mtime      time.Time // time of resolv.conf modification
- }
- 
- // See resolv.conf(5) on a Linux machine.
-@@ -33,11 +72,20 @@ func dnsReadConfig(filename string) *dnsConfig {
  	}
  	file, err := open(filename)
  	if err != nil {
 -		conf.servers = defaultNS
 +		conf.servers = getDefaultNS()
-+		conf.mtime = time.Now()
  		conf.err = err
  		return conf
  	}
- 	defer file.close()
+@@ -110,7 +156,7 @@ func dnsReadConfig(filename string) *dnsConfig {
-+	if fi, err := file.file.Stat(); err == nil {
-+		conf.mtime = fi.ModTime()
-+	} else {
-+		conf.mtime = time.Now()
-+		conf.servers = getDefaultNS()
-+		conf.err = err
-+		return conf
-+	}
- 	for line, ok := file.readLine(); ok; line, ok = file.readLine() {
- 		if len(line) > 0 && (line[0] == ';' || line[0] == '#') {
- 			// comment.
-@@ -51,7 +99,7 @@ func dnsReadConfig(filename string) *dnsConfig {
- 		case "nameserver": // add one name server
- 			if len(f) > 1 && len(conf.servers) < 3 { // small, but the standard limit
- 				// One more check: make sure server name is
--				// just an IP address.  Otherwise we need DNS
-+				// just an IP address. Otherwise we need DNS
- 				// to look it up.
- 				if parseIPv4(f[1]) != nil {
- 					conf.servers = append(conf.servers, f[1])
-@@ -110,7 +158,7 @@ func dnsReadConfig(filename string) *dnsConfig {
  		}
  	}
  	if len(conf.servers) == 0 {
@@ -110,8 +92,3 @@ index 6073fdb..9df3cec 100644
  	}
  	return conf
  }
-@@ -118,3 +166,4 @@ func dnsReadConfig(filename string) *dnsConfig {
- func hasPrefix(s, prefix string) bool {
- 	return len(s) >= len(prefix) && s[:len(prefix)] == prefix
- }
-+