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package parse
import (
"errors"
"fmt"
"net"
"os"
"strings"
"github.com/coredns/coredns/plugin/pkg/transport"
"github.com/miekg/dns"
)
// ErrNoNameservers is returned by HostPortOrFile if no servers can be parsed.
var ErrNoNameservers = errors.New("no nameservers found")
// Strips the zone, but preserves any port that comes after the zone
func stripZone(host string) string {
if strings.Contains(host, "%") {
lastPercent := strings.LastIndex(host, "%")
newHost := host[:lastPercent]
return newHost
}
return host
}
// HostPortOrFile parses the strings in s, each string can either be a
// address, [scheme://]address:port or a filename. The address part is checked
// and in case of filename a resolv.conf like file is (assumed) and parsed and
// the nameservers found are returned.
func HostPortOrFile(s ...string) ([]string, error) {
var servers []string
for _, h := range s {
trans, host := Transport(h)
if len(host) == 0 {
return servers, fmt.Errorf("invalid address: %q", h)
}
if trans == transport.UNIX {
servers = append(servers, trans+"://"+host)
continue
}
addr, _, err := net.SplitHostPort(host)
if err != nil {
// Parse didn't work, it is not a addr:port combo
hostNoZone := stripZone(host)
if net.ParseIP(hostNoZone) == nil {
ss, err := tryFile(host)
if err == nil {
servers = append(servers, ss...)
continue
}
return servers, fmt.Errorf("not an IP address or file: %q", host)
}
var ss string
switch trans {
case transport.DNS:
ss = net.JoinHostPort(host, transport.Port)
case transport.TLS:
ss = transport.TLS + "://" + net.JoinHostPort(host, transport.TLSPort)
case transport.QUIC:
ss = transport.QUIC + "://" + net.JoinHostPort(host, transport.QUICPort)
case transport.GRPC:
ss = transport.GRPC + "://" + net.JoinHostPort(host, transport.GRPCPort)
case transport.HTTPS:
ss = transport.HTTPS + "://" + net.JoinHostPort(host, transport.HTTPSPort)
}
servers = append(servers, ss)
continue
}
if net.ParseIP(stripZone(addr)) == nil {
ss, err := tryFile(host)
if err == nil {
servers = append(servers, ss...)
continue
}
return servers, fmt.Errorf("not an IP address or file: %q", host)
}
servers = append(servers, h)
}
if len(servers) == 0 {
return servers, ErrNoNameservers
}
return servers, nil
}
// Try to open this is a file first.
func tryFile(s string) ([]string, error) {
c, err := dns.ClientConfigFromFile(s)
if err == os.ErrNotExist {
return nil, fmt.Errorf("failed to open file %q: %q", s, err)
} else if err != nil {
return nil, err
}
servers := []string{}
for _, s := range c.Servers {
servers = append(servers, net.JoinHostPort(stripZone(s), c.Port))
}
return servers, nil
}
// HostPort will check if the host part is a valid IP address, if the
// IP address is valid, but no port is found, defaultPort is added.
func HostPort(s, defaultPort string) (string, error) {
addr, port, err := net.SplitHostPort(s)
if port == "" {
port = defaultPort
}
if err != nil {
if net.ParseIP(s) == nil {
return "", fmt.Errorf("must specify an IP address: `%s'", s)
}
return net.JoinHostPort(s, port), nil
}
if net.ParseIP(addr) == nil {
return "", fmt.Errorf("must specify an IP address: `%s'", addr)
}
return net.JoinHostPort(addr, port), nil
}
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