Mercurial > gemma
view controllers/externalwfs.go @ 350:1ea90a22bd15
Better replacements for WFS proxy.
author | Sascha L. Teichmann <sascha.teichmann@intevation.de> |
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date | Mon, 06 Aug 2018 18:13:58 +0200 |
parents | 56f6c5ab0f3d |
children | b89138a25f9e |
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package controllers import ( "compress/gzip" "encoding/xml" "io" "log" "net/http" "net/url" "strings" "github.com/gorilla/mux" "golang.org/x/net/html/charset" "gemma.intevation.de/gemma/config" ) type RoundTripFunc func(*http.Request) (*http.Response, error) func (rtf RoundTripFunc) RoundTrip(req *http.Request) (*http.Response, error) { return rtf(req) } func externalWFSDirector(req *http.Request) { abort := func(format string, args ...interface{}) { log.Printf(format, args...) panic(http.ErrAbortHandler) } external := config.ExternalWFSs() if external == nil || len(external) == 0 { abort("No external WFS proxy config found\n") } vars := mux.Vars(req) wfs := vars["wfs"] rest := vars["rest"] log.Printf("rest: %s\n", rest) alias, found := external[wfs] if !found { abort("No config found for %s\n", wfs) } data, ok := alias.(map[string]interface{}) if !ok { abort("error: badly configured external WFS %s\n", wfs) } urlS, found := data["url"] if !found { abort("error: missing url for external WFS %s\n", wfs) } prefix, ok := urlS.(string) if !ok { abort("error: badly configured url for external WFS %s\n", wfs) } log.Printf("%v\n", prefix) nURL := prefix + "/" + rest + "?" + req.URL.RawQuery log.Printf("%v\n", nURL) u, err := url.Parse(nURL) if err != nil { abort("Invalid url: %v\n", err) } req.URL = u req.Header.Set("X-Gemma-From", prefix) to := useHTTPS(req) + "://" + req.Host + "/api/externalwfs/" + wfs req.Header.Set("X-Gemma-To", to) req.Host = u.Host //log.Printf("headers: %v\n", req.Header) } func externalWFSTransport(req *http.Request) (*http.Response, error) { from := req.Header.Get("X-Gemma-From") to := req.Header.Get("X-Gemma-To") req.Header.Del("X-Gemma-From") req.Header.Del("X-Gemma-To") // To prevent some caching effects. req.Header.Del("If-None-Match") resp, err := http.DefaultTransport.RoundTrip(req) if err != nil { return nil, err } resp.Header.Set("X-Gemma-From", from) resp.Header.Set("X-Gemma-To", to) return resp, err } func externalWFSModifyResponse(resp *http.Response) error { from := resp.Header.Get("X-Gemma-From") to := resp.Header.Get("X-Gemma-To") resp.Header.Del("X-Gemma-From") resp.Header.Del("X-Gemma-To") xml := isXML(resp.Header) gzipped := strings.Contains(resp.Header.Get("Content-Encoding"), "gzip") if xml { log.Printf("rewrite from %s to %s\n", from, to) pr, pw := io.Pipe() var r io.ReadCloser var w io.WriteCloser if gzipped { var err error r, err = gzip.NewReader(resp.Body) if err != nil { return err } w = gzip.NewWriter(pw) } else { r = resp.Body w = pw } go func(force io.ReadCloser) { defer func() { w.Close() pw.Close() force.Close() }() /* if _, err := io.Copy(pw, r); err != nil { log.Printf("rewrite failed: %v\n", err) return } */ if err := rewrite(w, r, from, to); err != nil { log.Printf("rewrite failed: %v\n", err) return } log.Println("rewrite successful") }(resp.Body) resp.Body = pr } return nil } func isXML(h http.Header) bool { for _, t := range h["Content-Type"] { t = strings.ToLower(t) if strings.Contains(t, "text/xml") || strings.Contains(t, "application/xml") { return true } } return false } func rewrite(w io.Writer, r io.Reader, from, to string) error { decoder := xml.NewDecoder(r) decoder.CharsetReader = charset.NewReaderLabel encoder := xml.NewEncoder(w) replace := func(s string) string { return strings.Replace(s, from, to, -1) } //var ns nsdef tokens: for { tok, err := decoder.Token() switch { case tok == nil && err == io.EOF: break tokens case err != nil: return err } switch t := tok.(type) { case xml.StartElement: //ns = ns.push() t = t.Copy() attr := make([]xml.Attr, len(t.Attr)) //var lns string for i, at := range t.Attr { switch { case at.Name.Space == "xmlns": //ns.define(at.Value, at.Name.Local) attr[i] = xml.Attr{Name: at.Name, Value: at.Value} default: attr[i] = xml.Attr{Name: at.Name, Value: replace(at.Value)} } } //if s := ns.lookup(t.Name.Space); s != "" { // t.Name.Space = "" // t.Name.Local = s + ":" + t.Name.Local //} t.Attr = attr tok = t case xml.CharData: tok = xml.CharData(replace(string(t))) case xml.EndElement: //log.Printf("lookup %s -> %s\n", t.Name.Space, ns.lookup(t.Name.Space)) //if s := ns.lookup(t.Name.Space); s != "" { // t.Name.Space = "" // t.Name.Local = s + ":" + t.Name.Local // tok = t // } // ns = ns.pop() } if err := encoder.EncodeToken(tok); err != nil { return err } } return encoder.Flush() } type nsdef []map[string]string func (n nsdef) lookup(ns string) string { for i := len(n) - 1; i >= 0; i-- { if s := n[i][ns]; s != "" { return s } } return "" } func (n nsdef) push() nsdef { return append(n, make(map[string]string)) } func (n nsdef) pop() nsdef { if l := len(n); l > 0 { n[l-1] = nil n = n[:l-1] } return n } func (n nsdef) define(ns, s string) { if n != nil { n[len(n)-1][ns] = s } }