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c4ab98c6e3
This checks if the next middleware to be called is nil, and if so returns ServerFailure and an error. This makes the next calling more robust and saves some lines of code. Also prefix the error with the name of the middleware to aid in debugging.
83 lines
2.1 KiB
Go
83 lines
2.1 KiB
Go
package dnsutil
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import (
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"fmt"
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"net"
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"os"
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"github.com/miekg/dns"
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)
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// ParseHostPortOrFile parses the strings in s, each string can either be a address,
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// address:port or a filename. The address part is checked and the filename case a
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// resolv.conf like file is parsed and the nameserver found are returned.
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func ParseHostPortOrFile(s ...string) ([]string, error) {
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var servers []string
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for _, host := range s {
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addr, _, err := net.SplitHostPort(host)
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if err != nil {
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// Parse didn't work, it is not a addr:port combo
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if net.ParseIP(host) == nil {
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// Not an IP address.
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ss, err := tryFile(host)
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if err == nil {
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servers = append(servers, ss...)
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continue
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}
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return servers, fmt.Errorf("not an IP address or file: %q", host)
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}
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ss := net.JoinHostPort(host, "53")
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servers = append(servers, ss)
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continue
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}
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if net.ParseIP(addr) == nil {
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// No an IP address.
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ss, err := tryFile(host)
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if err == nil {
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servers = append(servers, ss...)
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continue
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}
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return servers, fmt.Errorf("not an IP address or file: %q", host)
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}
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servers = append(servers, host)
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}
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return servers, nil
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}
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// Try to open this is a file first.
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func tryFile(s string) ([]string, error) {
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c, err := dns.ClientConfigFromFile(s)
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if err == os.ErrNotExist {
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return nil, fmt.Errorf("failed to open file %q: %q", s, err)
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} else if err != nil {
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return nil, err
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}
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servers := []string{}
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for _, s := range c.Servers {
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servers = append(servers, net.JoinHostPort(s, c.Port))
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}
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return servers, nil
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}
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// ParseHostPort will check if the host part is a valid IP address, if the
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// IP address is valid, but no port is found, defaultPort is added.
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func ParseHostPort(s, defaultPort string) (string, error) {
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addr, port, err := net.SplitHostPort(s)
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if port == "" {
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port = defaultPort
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}
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if err != nil {
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if net.ParseIP(s) == nil {
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return "", fmt.Errorf("must specify an IP address: `%s'", s)
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}
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return net.JoinHostPort(s, port), nil
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}
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if net.ParseIP(addr) == nil {
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return "", fmt.Errorf("must specify an IP address: `%s'", addr)
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}
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return net.JoinHostPort(addr, port), nil
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}
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