109 lines
2.9 KiB
Go
109 lines
2.9 KiB
Go
package app
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import (
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"fmt"
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"net"
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"net/url"
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"github.com/mr-karan/doggo/pkg/config"
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"github.com/mr-karan/doggo/pkg/models"
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)
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// LoadNameservers reads all the user given
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// nameservers and loads to App.
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func (app *App) LoadNameservers() error {
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for _, srv := range app.QueryFlags.Nameservers {
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ns, err := initNameserver(srv)
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if err != nil {
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return fmt.Errorf("error parsing nameserver: %s", srv)
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}
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// check if properly initialised.
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if ns.Address != "" && ns.Type != "" {
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app.Nameservers = append(app.Nameservers, ns)
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}
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}
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// Set `ndots` to the user specified value.
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app.ResolverOpts.Ndots = app.QueryFlags.Ndots
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// fallback to system nameserver
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// in case no nameserver is specified by user.
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if len(app.Nameservers) == 0 {
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ns, ndots, search, err := getDefaultServers()
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if err != nil {
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return fmt.Errorf("error fetching system default nameserver")
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}
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// `-1` indicates the flag is not set.
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// use from config if user hasn't specified any value.
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if app.ResolverOpts.Ndots == -1 {
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app.ResolverOpts.Ndots = ndots
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}
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if len(search) > 0 && app.QueryFlags.UseSearchList {
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app.ResolverOpts.SearchList = search
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}
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app.Nameservers = append(app.Nameservers, ns...)
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}
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// if the user hasn't given any override of `ndots` AND has
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// given a custom nameserver. Set `ndots` to 1 as the fallback value
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if app.ResolverOpts.Ndots == -1 {
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app.ResolverOpts.Ndots = 0
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}
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return nil
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}
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func initNameserver(n string) (models.Nameserver, error) {
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// Instantiate a UDP resolver with default port as a fallback.
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ns := models.Nameserver{
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Type: models.UDPResolver,
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Address: net.JoinHostPort(n, models.DefaultUDPPort),
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}
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u, err := url.Parse(n)
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if err != nil {
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return ns, err
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}
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if u.Scheme == "https" {
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ns.Type = models.DOHResolver
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ns.Address = u.String()
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}
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if u.Scheme == "tls" {
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ns.Type = models.DOTResolver
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if u.Port() == "" {
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ns.Address = net.JoinHostPort(u.Hostname(), models.DefaultTLSPort)
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} else {
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ns.Address = net.JoinHostPort(u.Hostname(), u.Port())
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}
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}
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if u.Scheme == "tcp" {
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ns.Type = models.TCPResolver
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if u.Port() == "" {
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ns.Address = net.JoinHostPort(u.Hostname(), models.DefaultTCPPort)
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} else {
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ns.Address = net.JoinHostPort(u.Hostname(), u.Port())
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}
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}
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if u.Scheme == "udp" {
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ns.Type = models.UDPResolver
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if u.Port() == "" {
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ns.Address = net.JoinHostPort(u.Hostname(), models.DefaultUDPPort)
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} else {
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ns.Address = net.JoinHostPort(u.Hostname(), u.Port())
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}
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}
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return ns, nil
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}
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func getDefaultServers() ([]models.Nameserver, int, []string, error) {
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dnsServers, ndots, search, err := config.GetDefaultServers()
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if err != nil {
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return nil, 0, nil, err
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}
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servers := make([]models.Nameserver, 0, len(dnsServers))
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for _, s := range dnsServers {
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ns := models.Nameserver{
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Type: models.UDPResolver,
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Address: net.JoinHostPort(s, models.DefaultUDPPort),
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}
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servers = append(servers, ns)
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}
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return servers, ndots, search, nil
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}
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