diff options
Diffstat (limited to 'middleware/autopath/autopath.go')
| -rw-r--r-- | middleware/autopath/autopath.go | 152 |
1 files changed, 0 insertions, 152 deletions
diff --git a/middleware/autopath/autopath.go b/middleware/autopath/autopath.go deleted file mode 100644 index 94db8bc56..000000000 --- a/middleware/autopath/autopath.go +++ /dev/null @@ -1,152 +0,0 @@ -/* -Package autopath implements autopathing. This is a hack; it shortcuts the -client's search path resolution by performing these lookups on the server... - -The server has a copy (via AutoPathFunc) of the client's search path and on -receiving a query it first establish if the suffix matches the FIRST configured -element. If no match can be found the query will be forwarded up the middleware -chain without interference (iff 'fallthrough' has been set). - -If the query is deemed to fall in the search path the server will perform the -queries with each element of the search path appended in sequence until a -non-NXDOMAIN answer has been found. That reply will then be returned to the -client - with some CNAME hackery to let the client accept the reply. - -If all queries return NXDOMAIN we return the original as-is and let the client -continue searching. The client will go to the next element in the search path, -but we won’t do any more autopathing. It means that in the failure case, you do -more work, since the server looks it up, then the client still needs to go -through the search path. - -It is assume the search path ordering is identical between server and client. - -Midldeware implementing autopath, must have a function called `AutoPath` of type -autopath.Func. Note the searchpath must be ending with the empty string. - -I.e: - -func (m Middleware ) AutoPath(state request.Request) []string { - return []string{"first", "second", "last", ""} -} -*/ -package autopath - -import ( - "log" - - "github.com/coredns/coredns/middleware" - "github.com/coredns/coredns/middleware/pkg/dnsutil" - "github.com/coredns/coredns/middleware/pkg/nonwriter" - "github.com/coredns/coredns/request" - - "github.com/miekg/dns" - "golang.org/x/net/context" -) - -// Func defines the function middleware should implement to return a search -// path to the autopath middleware. The last element of the slice must be the empty string. -// If Func returns a nil slice, no autopathing will be done. -type Func func(request.Request) []string - -// AutoPath perform autopath: service side search path completion. -type AutoPath struct { - Next middleware.Handler - Zones []string - - // Search always includes "" as the last element, so we try the base query with out any search paths added as well. - search []string - searchFunc Func -} - -// ServeDNS implements the middleware.Handle interface. -func (a *AutoPath) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) { - state := request.Request{W: w, Req: r} - - zone := middleware.Zones(a.Zones).Matches(state.Name()) - if zone == "" { - return middleware.NextOrFailure(a.Name(), a.Next, ctx, w, r) - } - - // Check if autopath should be done, searchFunc takes precedence over the local configured search path. - var err error - searchpath := a.search - - if a.searchFunc != nil { - searchpath = a.searchFunc(state) - } - - if len(searchpath) == 0 { - log.Printf("[WARNING] No search path available for autopath") - return middleware.NextOrFailure(a.Name(), a.Next, ctx, w, r) - } - - if !firstInSearchPath(state.Name(), searchpath) { - return middleware.NextOrFailure(a.Name(), a.Next, ctx, w, r) - } - - origQName := state.QName() - - // Establish base name of the query. I.e what was originally asked. - base, err := dnsutil.TrimZone(state.QName(), searchpath[0]) // TODO(miek): we loose the original case of the query here. - if err != nil { - return dns.RcodeServerFailure, err - } - - firstReply := new(dns.Msg) - firstRcode := 0 - var firstErr error - - ar := r.Copy() - // Walk the search path and see if we can get a non-nxdomain - if they all fail we return the first - // query we've done and return that as-is. This means the client will do the search path walk again... - for i, s := range searchpath { - newQName := base + "." + s - ar.Question[0].Name = newQName - nw := nonwriter.New(w) - - rcode, err := middleware.NextOrFailure(a.Name(), a.Next, ctx, nw, ar) - if err != nil { - // Return now - not sure if this is the best. We should also check if the write has happened. - return rcode, err - } - if i == 0 { - firstReply = nw.Msg - firstRcode = rcode - firstErr = err - } - - if !middleware.ClientWrite(rcode) { - continue - } - - if nw.Msg.Rcode == dns.RcodeNameError { - continue - } - - msg := nw.Msg - cnamer(msg, origQName) - - // Write whatever non-nxdomain answer we've found. - w.WriteMsg(msg) - return rcode, err - - } - if middleware.ClientWrite(firstRcode) { - w.WriteMsg(firstReply) - } - return firstRcode, firstErr -} - -// Name implements the Handler interface. -func (a *AutoPath) Name() string { return "autopath" } - -// firstInSearchPath checks if name is equal to are a sibling of the first element in the search path. -func firstInSearchPath(name string, searchpath []string) bool { - if name == searchpath[0] { - return true - } - if dns.IsSubDomain(searchpath[0], name) { - return true - } - return false -} |