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-rw-r--r--plugin/hosts/README.md3
-rw-r--r--plugin/hosts/hosts_test.go5
-rw-r--r--plugin/hosts/hostsfile.go151
-rw-r--r--plugin/hosts/hostsfile_test.go5
-rw-r--r--plugin/hosts/setup.go37
-rw-r--r--plugin/hosts/setup_test.go2
6 files changed, 122 insertions, 81 deletions
diff --git a/plugin/hosts/README.md b/plugin/hosts/README.md
index e792ff207..0476e63bb 100644
--- a/plugin/hosts/README.md
+++ b/plugin/hosts/README.md
@@ -17,7 +17,8 @@ hosts [FILE [ZONES...]] {
~~~
* **FILE** the hosts file to read and parse. If the path is relative the path from the *root*
- directive will be prepended to it. Defaults to /etc/hosts if omitted
+ directive will be prepended to it. Defaults to /etc/hosts if omitted. We scan the file for changes
+ every 5 seconds.
* **ZONES** zones it should be authoritative for. If empty, the zones from the configuration block
are used.
* **INLINE** the hosts file contents inlined in Corefile. If there are any lines before fallthrough
diff --git a/plugin/hosts/hosts_test.go b/plugin/hosts/hosts_test.go
index 3c9405562..6d5f7955f 100644
--- a/plugin/hosts/hosts_test.go
+++ b/plugin/hosts/hosts_test.go
@@ -3,7 +3,6 @@ package hosts
import (
"strings"
"testing"
- "time"
"github.com/coredns/coredns/plugin/pkg/dnstest"
"github.com/coredns/coredns/plugin/test"
@@ -13,8 +12,8 @@ import (
)
func TestLookupA(t *testing.T) {
- h := Hosts{Next: test.ErrorHandler(), Hostsfile: &Hostsfile{expire: time.Now().Add(1 * time.Hour), Origins: []string{"."}}}
- h.Parse(strings.NewReader(hostsExample))
+ h := Hosts{Next: test.ErrorHandler(), Hostsfile: &Hostsfile{Origins: []string{"."}}}
+ h.parseReader(strings.NewReader(hostsExample))
ctx := context.TODO()
diff --git a/plugin/hosts/hostsfile.go b/plugin/hosts/hostsfile.go
index dbbc283b2..4b912b17c 100644
--- a/plugin/hosts/hostsfile.go
+++ b/plugin/hosts/hostsfile.go
@@ -19,8 +19,6 @@ import (
"github.com/coredns/coredns/plugin"
)
-const cacheMaxAge = 5 * time.Second
-
func parseLiteralIP(addr string) net.IP {
if i := strings.Index(addr, "%"); i >= 0 {
// discard ipv6 zone
@@ -34,13 +32,7 @@ func absDomainName(b string) string {
return plugin.Name(b).Normalize()
}
-// Hostsfile contains known host entries.
-type Hostsfile struct {
- sync.RWMutex
-
- // list of zones we are authoritive for
- Origins []string
-
+type hostsMap struct {
// Key for the list of literal IP addresses must be a host
// name. It would be part of DNS labels, a FQDN or an absolute
// FQDN.
@@ -52,71 +44,80 @@ type Hostsfile struct {
// including IPv6 address with zone identifier.
// We don't support old-classful IP address notation.
byAddr map[string][]string
+}
- // inline saves the hosts file is inlined in Corefile
- // We need a copy here as we want to use inline to override
- // the default /etc/hosts
- inline []string
-
- expire time.Time
- path string
- mtime time.Time
- size int64
+func newHostsMap() *hostsMap {
+ return &hostsMap{
+ byNameV4: make(map[string][]net.IP),
+ byNameV6: make(map[string][]net.IP),
+ byAddr: make(map[string][]string),
+ }
}
-// ReadHosts determines if the cached data needs to be updated based on the size and modification time of the hostsfile.
-func (h *Hostsfile) ReadHosts() {
- now := time.Now()
+// Hostsfile contains known host entries.
+type Hostsfile struct {
+ sync.RWMutex
- // Not deferring h.RUnlock() because we may need to remove the read lock and aquire a write lock
- h.RLock()
- if now.Before(h.expire) && len(h.byAddr) > 0 {
- h.RUnlock()
- return
- }
- stat, err := os.Stat(h.path)
- if err == nil && h.mtime.Equal(stat.ModTime()) && h.size == stat.Size() {
- h.RUnlock()
- h.Lock()
- h.expire = now.Add(cacheMaxAge)
- h.Unlock()
+ // list of zones we are authoritive for
+ Origins []string
+
+ // hosts maps for lookups
+ hmap *hostsMap
+
+ // inline saves the hosts file that is inlined in a Corefile.
+ // We need a copy here as we want to use it to initialize the maps for parse.
+ inline *hostsMap
+
+ // path to the hosts file
+ path string
+
+ // mtime and size are only read and modified by a single goroutine
+ mtime time.Time
+ size int64
+}
+
+// readHosts determines if the cached data needs to be updated based on the size and modification time of the hostsfile.
+func (h *Hostsfile) readHosts() {
+ file, err := os.Open(h.path)
+ if err != nil {
+ // We already log a warning if the file doesn't exist or can't be opened on setup. No need to return the error here.
return
}
+ defer file.Close()
- var file *os.File
- if file, _ = os.Open(h.path); file == nil {
- // If this is the first time then we will try to parse inline
- if len(h.byAddr) == 0 && len(h.inline) > 0 {
- h.Parse(nil)
- }
- h.RUnlock()
+ stat, err := file.Stat()
+ if err == nil && h.mtime.Equal(stat.ModTime()) && h.size == stat.Size() {
return
}
- defer file.Close()
- h.RUnlock()
h.Lock()
defer h.Unlock()
- h.Parse(file)
+ h.parseReader(file)
// Update the data cache.
- h.expire = now.Add(cacheMaxAge)
h.mtime = stat.ModTime()
h.size = stat.Size()
}
-// Parse reads the hostsfile and populates the byName and byAddr maps.
-func (h *Hostsfile) Parse(file io.Reader) {
- hsv4 := make(map[string][]net.IP)
- hsv6 := make(map[string][]net.IP)
- is := make(map[string][]string)
-
- var readers []io.Reader
- if file != nil {
- readers = append(readers, file)
+func (h *Hostsfile) initInline(inline []string) {
+ if len(inline) == 0 {
+ return
}
- readers = append(readers, strings.NewReader(strings.Join(h.inline, "\n")))
- scanner := bufio.NewScanner(io.MultiReader(readers...))
+
+ hmap := newHostsMap()
+ h.inline = h.parse(strings.NewReader(strings.Join(inline, "\n")), hmap)
+ *h.hmap = *h.inline
+}
+
+func (h *Hostsfile) parseReader(r io.Reader) {
+ h.hmap = h.parse(r, h.inline)
+}
+
+// Parse reads the hostsfile and populates the byName and byAddr maps.
+func (h *Hostsfile) parse(r io.Reader, override *hostsMap) *hostsMap {
+ hmap := newHostsMap()
+
+ scanner := bufio.NewScanner(r)
for scanner.Scan() {
line := scanner.Bytes()
if i := bytes.Index(line, []byte{'#'}); i >= 0 {
@@ -140,18 +141,31 @@ func (h *Hostsfile) Parse(file io.Reader) {
}
switch ver {
case 4:
- hsv4[name] = append(hsv4[name], addr)
+ hmap.byNameV4[name] = append(hmap.byNameV4[name], addr)
case 6:
- hsv6[name] = append(hsv6[name], addr)
+ hmap.byNameV6[name] = append(hmap.byNameV6[name], addr)
default:
continue
}
- is[addr.String()] = append(is[addr.String()], name)
+ hmap.byAddr[addr.String()] = append(hmap.byAddr[addr.String()], name)
}
}
- h.byNameV4 = hsv4
- h.byNameV6 = hsv6
- h.byAddr = is
+
+ if override == nil {
+ return hmap
+ }
+
+ for name := range override.byNameV4 {
+ hmap.byNameV4[name] = append(hmap.byNameV4[name], override.byNameV4[name]...)
+ }
+ for name := range override.byNameV4 {
+ hmap.byNameV6[name] = append(hmap.byNameV6[name], override.byNameV6[name]...)
+ }
+ for addr := range override.byAddr {
+ hmap.byAddr[addr] = append(hmap.byAddr[addr], override.byAddr[addr]...)
+ }
+
+ return hmap
}
// ipVersion returns what IP version was used textually
@@ -169,11 +183,10 @@ func ipVersion(s string) int {
// LookupStaticHostV4 looks up the IPv4 addresses for the given host from the hosts file.
func (h *Hostsfile) LookupStaticHostV4(host string) []net.IP {
- h.ReadHosts()
h.RLock()
defer h.RUnlock()
- if len(h.byNameV4) != 0 {
- if ips, ok := h.byNameV4[absDomainName(host)]; ok {
+ if len(h.hmap.byNameV4) != 0 {
+ if ips, ok := h.hmap.byNameV4[absDomainName(host)]; ok {
ipsCp := make([]net.IP, len(ips))
copy(ipsCp, ips)
return ipsCp
@@ -184,11 +197,10 @@ func (h *Hostsfile) LookupStaticHostV4(host string) []net.IP {
// LookupStaticHostV6 looks up the IPv6 addresses for the given host from the hosts file.
func (h *Hostsfile) LookupStaticHostV6(host string) []net.IP {
- h.ReadHosts()
h.RLock()
defer h.RUnlock()
- if len(h.byNameV6) != 0 {
- if ips, ok := h.byNameV6[absDomainName(host)]; ok {
+ if len(h.hmap.byNameV6) != 0 {
+ if ips, ok := h.hmap.byNameV6[absDomainName(host)]; ok {
ipsCp := make([]net.IP, len(ips))
copy(ipsCp, ips)
return ipsCp
@@ -199,15 +211,14 @@ func (h *Hostsfile) LookupStaticHostV6(host string) []net.IP {
// LookupStaticAddr looks up the hosts for the given address from the hosts file.
func (h *Hostsfile) LookupStaticAddr(addr string) []string {
- h.ReadHosts()
h.RLock()
defer h.RUnlock()
addr = parseLiteralIP(addr).String()
if addr == "" {
return nil
}
- if len(h.byAddr) != 0 {
- if hosts, ok := h.byAddr[addr]; ok {
+ if len(h.hmap.byAddr) != 0 {
+ if hosts, ok := h.hmap.byAddr[addr]; ok {
hostsCp := make([]string, len(hosts))
copy(hostsCp, hosts)
return hostsCp
diff --git a/plugin/hosts/hostsfile_test.go b/plugin/hosts/hostsfile_test.go
index 65841fa42..cb923ab60 100644
--- a/plugin/hosts/hostsfile_test.go
+++ b/plugin/hosts/hostsfile_test.go
@@ -9,12 +9,11 @@ import (
"reflect"
"strings"
"testing"
- "time"
)
func testHostsfile(file string) *Hostsfile {
- h := &Hostsfile{expire: time.Now().Add(1 * time.Hour), Origins: []string{"."}}
- h.Parse(strings.NewReader(file))
+ h := &Hostsfile{Origins: []string{"."}}
+ h.parseReader(strings.NewReader(file))
return h
}
diff --git a/plugin/hosts/setup.go b/plugin/hosts/setup.go
index 48beb0dcb..1b281b9a3 100644
--- a/plugin/hosts/setup.go
+++ b/plugin/hosts/setup.go
@@ -5,6 +5,7 @@ import (
"os"
"path"
"strings"
+ "time"
"github.com/coredns/coredns/core/dnsserver"
"github.com/coredns/coredns/plugin"
@@ -25,6 +26,30 @@ func setup(c *caddy.Controller) error {
return plugin.Error("hosts", err)
}
+ parseChan := make(chan bool)
+
+ c.OnStartup(func() error {
+ h.readHosts()
+
+ go func() {
+ ticker := time.NewTicker(5 * time.Second)
+ for {
+ select {
+ case <-parseChan:
+ return
+ case <-ticker.C:
+ h.readHosts()
+ }
+ }
+ }()
+ return nil
+ })
+
+ c.OnShutdown(func() error {
+ close(parseChan)
+ return nil
+ })
+
dnsserver.GetConfig(c).AddPlugin(func(next plugin.Handler) plugin.Handler {
h.Next = next
return h
@@ -35,12 +60,15 @@ func setup(c *caddy.Controller) error {
func hostsParse(c *caddy.Controller) (Hosts, error) {
var h = Hosts{
- Hostsfile: &Hostsfile{path: "/etc/hosts"},
+ Hostsfile: &Hostsfile{
+ path: "/etc/hosts",
+ hmap: newHostsMap(),
+ },
}
- defer h.ReadHosts()
config := dnsserver.GetConfig(c)
+ inline := []string{}
for c.Next() {
args := c.RemainingArgs()
if len(args) >= 1 {
@@ -86,12 +114,15 @@ func hostsParse(c *caddy.Controller) (Hosts, error) {
default:
if !h.Fallthrough {
line := strings.Join(append([]string{c.Val()}, c.RemainingArgs()...), " ")
- h.inline = append(h.inline, line)
+ inline = append(inline, line)
continue
}
return h, c.Errf("unknown property '%s'", c.Val())
}
}
}
+
+ h.initInline(inline)
+
return h, nil
}
diff --git a/plugin/hosts/setup_test.go b/plugin/hosts/setup_test.go
index fefed6c72..b401d58dc 100644
--- a/plugin/hosts/setup_test.go
+++ b/plugin/hosts/setup_test.go
@@ -141,7 +141,7 @@ func TestHostsInlineParse(t *testing.T) {
t.Fatalf("Test %d expected fallthrough of %v, got %v", i, test.expectedFallthrough, h.Fallthrough)
}
for k, expectedVal := range test.expectedbyAddr {
- if val, ok := h.byAddr[k]; !ok {
+ if val, ok := h.hmap.byAddr[k]; !ok {
t.Fatalf("Test %d expected %v, got no entry", i, k)
} else {
if len(expectedVal) != len(val) {
generated by cgit v1.2.3 (git 2.39.1) at 2025-08-03 10:54:29 +0000