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|
package acl
import (
"net"
"strings"
"github.com/coredns/caddy"
"github.com/coredns/coredns/core/dnsserver"
"github.com/coredns/coredns/plugin"
"github.com/infobloxopen/go-trees/iptree"
"github.com/miekg/dns"
)
const pluginName = "acl"
func init() { plugin.Register(pluginName, setup) }
func newDefaultFilter() *iptree.Tree {
defaultFilter := iptree.NewTree()
_, IPv4All, _ := net.ParseCIDR("0.0.0.0/0")
_, IPv6All, _ := net.ParseCIDR("::/0")
defaultFilter.InplaceInsertNet(IPv4All, struct{}{})
defaultFilter.InplaceInsertNet(IPv6All, struct{}{})
return defaultFilter
}
func setup(c *caddy.Controller) error {
a, err := parse(c)
if err != nil {
return plugin.Error(pluginName, err)
}
dnsserver.GetConfig(c).AddPlugin(func(next plugin.Handler) plugin.Handler {
a.Next = next
return a
})
return nil
}
func parse(c *caddy.Controller) (ACL, error) {
a := ACL{}
for c.Next() {
r := rule{}
args := c.RemainingArgs()
r.zones = plugin.OriginsFromArgsOrServerBlock(args, c.ServerBlockKeys)
for c.NextBlock() {
p := policy{}
action := strings.ToLower(c.Val())
if action == "allow" {
p.action = actionAllow
} else if action == "block" {
p.action = actionBlock
} else if action == "filter" {
p.action = actionFilter
} else if action == "drop" {
p.action = actionDrop
} else {
return a, c.Errf("unexpected token %q; expect 'allow', 'block', 'filter' or 'drop'", c.Val())
}
p.qtypes = make(map[uint16]struct{})
p.filter = iptree.NewTree()
hasTypeSection := false
hasNetSection := false
remainingTokens := c.RemainingArgs()
for len(remainingTokens) > 0 {
if !isPreservedIdentifier(remainingTokens[0]) {
return a, c.Errf("unexpected token %q; expect 'type | net'", remainingTokens[0])
}
section := strings.ToLower(remainingTokens[0])
i := 1
var tokens []string
for ; i < len(remainingTokens) && !isPreservedIdentifier(remainingTokens[i]); i++ {
tokens = append(tokens, remainingTokens[i])
}
remainingTokens = remainingTokens[i:]
if len(tokens) == 0 {
return a, c.Errf("no token specified in %q section", section)
}
switch section {
case "type":
hasTypeSection = true
for _, token := range tokens {
if token == "*" {
p.qtypes[dns.TypeNone] = struct{}{}
break
}
qtype, ok := dns.StringToType[token]
if !ok {
return a, c.Errf("unexpected token %q; expect legal QTYPE", token)
}
p.qtypes[qtype] = struct{}{}
}
case "net":
hasNetSection = true
for _, token := range tokens {
if token == "*" {
p.filter = newDefaultFilter()
break
}
token = normalize(token)
_, source, err := net.ParseCIDR(token)
if err != nil {
return a, c.Errf("illegal CIDR notation %q", token)
}
p.filter.InplaceInsertNet(source, struct{}{})
}
default:
return a, c.Errf("unexpected token %q; expect 'type | net'", section)
}
}
// optional `type` section means all record types.
if !hasTypeSection {
p.qtypes[dns.TypeNone] = struct{}{}
}
// optional `net` means all ip addresses.
if !hasNetSection {
p.filter = newDefaultFilter()
}
r.policies = append(r.policies, p)
}
a.Rules = append(a.Rules, r)
}
return a, nil
}
func isPreservedIdentifier(token string) bool {
identifier := strings.ToLower(token)
return identifier == "type" || identifier == "net"
}
// normalize appends '/32' for any single IPv4 address and '/128' for IPv6.
func normalize(rawNet string) string {
if idx := strings.IndexAny(rawNet, "/"); idx >= 0 {
return rawNet
}
if idx := strings.IndexAny(rawNet, ":"); idx >= 0 {
return rawNet + "/128"
}
return rawNet + "/32"
}
|
