b56b080a7c
* introduce new interface "dnsserver.Viewer", that allows a plugin implementing it to decide if a query should be routed into its server block. * add new plugin "view", that uses the new interface to enable a user to define expression based conditions that must be met for a query to be routed to its server block. Signed-off-by: Chris O'Haver <cohaver@infoblox.com>
65 lines
1.2 KiB
Go
65 lines
1.2 KiB
Go
package view
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import (
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"context"
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"strings"
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"github.com/coredns/caddy"
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"github.com/coredns/coredns/core/dnsserver"
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"github.com/coredns/coredns/plugin"
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"github.com/coredns/coredns/plugin/pkg/expression"
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"github.com/antonmedv/expr"
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)
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func init() { plugin.Register("view", setup) }
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func setup(c *caddy.Controller) error {
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cond, err := parse(c)
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if err != nil {
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return plugin.Error("view", err)
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}
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dnsserver.GetConfig(c).AddPlugin(func(next plugin.Handler) plugin.Handler {
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cond.Next = next
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return cond
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})
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return nil
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}
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func parse(c *caddy.Controller) (*View, error) {
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v := new(View)
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i := 0
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for c.Next() {
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i++
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if i > 1 {
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return nil, plugin.ErrOnce
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}
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args := c.RemainingArgs()
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if len(args) != 1 {
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return nil, c.ArgErr()
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}
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v.viewName = args[0]
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for c.NextBlock() {
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switch c.Val() {
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case "expr":
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args := c.RemainingArgs()
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prog, err := expr.Compile(strings.Join(args, " "), expr.Env(expression.DefaultEnv(context.Background(), nil)))
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if err != nil {
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return v, err
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}
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v.progs = append(v.progs, prog)
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if err != nil {
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return nil, err
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}
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continue
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default:
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return nil, c.Errf("unknown property '%s'", c.Val())
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}
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}
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}
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return v, nil
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}
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