307 lines
8.6 KiB
Go
307 lines
8.6 KiB
Go
package rushlink
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//go:generate go-bindata -pkg $GOPACKAGE -prefix assets/ assets/...
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import (
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"bytes"
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"fmt"
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html "html/template"
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"io"
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"log"
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"net/http"
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"path/filepath"
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"regexp"
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"runtime/debug"
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"sort"
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"strconv"
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"strings"
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text "text/template"
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"time"
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"github.com/pkg/errors"
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)
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const defaultScheme = "http"
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// Plain text templates
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var textBaseTemplate *text.Template = text.Must(text.New("").Parse(string(MustAsset("templates/txt/base.txt.tmpl"))))
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var htmlBaseTemplate *html.Template = html.Must(html.New("").Parse(string(MustAsset("templates/html/base.html.tmpl"))))
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// Template collections
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var textTemplates = make(map[string]*text.Template, 0)
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var htmlTemplates = make(map[string]*html.Template, 0)
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// Used by resolveResponseContentType
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var acceptHeaderMediaRangeRegex = regexp.MustCompile(`^\s*([^()<>@,;:\\"/\[\]?.=]+)/([^()<>@,;:\\"/\[\]?.=]+)\s*$`)
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var acceptHeaderAcceptParamsRegex = regexp.MustCompile(`^\s*(\w+)=([A-Za-z0-9.-]+)\s*$`)
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var acceptHeaderWeight = regexp.MustCompile(`^\s*q=0(?:\.([0-9]{0,3}))|1(?:\.0{0,3})\s*$`)
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// HTML templates
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func init() {
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for _, tmplPath := range AssetNames() {
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if mustMatch("templates/txt/*.txt.tmpl", tmplPath) {
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base := text.Must(textBaseTemplate.Clone())
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tmpl, err := base.Parse(string(MustAsset(tmplPath)))
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if err != nil {
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panic(errors.Wrapf(err, "parsing %v", tmplPath))
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}
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tmplName := strings.TrimSuffix(filepath.Base(tmplPath), ".txt.tmpl")
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textTemplates[tmplName] = tmpl
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continue
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}
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if mustMatch("templates/html/*.html.tmpl", tmplPath) {
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base := html.Must(htmlBaseTemplate.Clone())
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tmpl, err := base.Parse(string(MustAsset(tmplPath)))
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if err != nil {
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panic(errors.Wrapf(err, "parsing %v", tmplPath))
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}
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tmplName := strings.TrimSuffix(filepath.Base(tmplPath), ".html.tmpl")
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htmlTemplates[tmplName] = tmpl
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continue
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}
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}
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// Sanity check. Both maps should not be empty
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if len(textTemplates) == 0 || len(htmlTemplates) == 0 {
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panic("template loading failed")
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}
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}
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func mustMatch(pattern, name string) bool {
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m, err := filepath.Match(pattern, name)
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if err != nil {
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panic("%v error in call to mustMatch")
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}
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return m
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}
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func parseFail(tmplName string, err error) {
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panic(errors.Wrapf(err, "parsing of %v failed", tmplName))
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}
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func mapExtend(m map[string]interface{}, key string, value interface{}) {
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if m[key] != nil {
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return
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}
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m[key] = value
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}
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func (rl *rushlink) renderStatic(w http.ResponseWriter, r *http.Request, path string) {
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var modTime time.Time
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if info, err := AssetInfo(path); err == nil {
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modTime = info.ModTime()
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}
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contents, err := Asset(path)
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if err != nil {
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rl.renderError(w, r, http.StatusNotFound, err.Error())
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return
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}
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http.ServeContent(w, r, path, modTime, bytes.NewReader(contents))
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}
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func (rl *rushlink) render(w http.ResponseWriter, r *http.Request, status int, tmplName string, data map[string]interface{}) {
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contentType, err := resolveResponseContentType(r, []string{"text/plain", "text/html"})
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if err != nil {
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w.WriteHeader(http.StatusNotAcceptable)
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fmt.Fprintf(w, "error parsing Accept header: %v\n", err)
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return
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}
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// Add the request to the template data
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mapExtend(data, "RootURL", rl.resolveRootURL(r))
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mapExtend(data, "Request", r)
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switch contentType {
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case "text/plain":
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w.Header().Set("Content-Type", "text/plain")
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tmpl := textTemplates[tmplName]
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if tmpl == nil {
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err = fmt.Errorf("'%v' not in textTemplates", tmplName)
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break
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}
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if status != 0 {
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w.WriteHeader(status)
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}
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if r.Method != "HEAD" {
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err = tmpl.Execute(w, data)
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}
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case "text/html":
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w.Header().Set("Content-Type", "text/html")
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tmpl := htmlTemplates[tmplName]
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if tmpl == nil {
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err = fmt.Errorf("'%v' not in htmlTemplates", tmplName)
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break
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}
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// Construct a (lazy) plain-text view for inclusion in <pre>
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data["Pre"] = func() string {
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tmpl := textTemplates[tmplName]
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if tmpl == nil {
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panic(fmt.Errorf("'%v' not in textTemplates", tmplName))
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}
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var buf bytes.Buffer
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if err := tmpl.Execute(&buf, data); err != nil {
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panic(err)
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}
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return buf.String()
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}
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if status != 0 {
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w.WriteHeader(status)
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}
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if r.Method != "HEAD" {
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err = tmpl.Execute(w, data)
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}
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default:
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// Fall back to plain text without template
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w.WriteHeader(http.StatusNotAcceptable)
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io.WriteString(w, "could not resolve an acceptable content-type\n")
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}
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if err != nil {
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panic(err)
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}
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}
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func (rl *rushlink) renderError(w http.ResponseWriter, r *http.Request, status int, msg string) {
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rl.render(w, r, status, "error", map[string]interface{}{"Message": msg})
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}
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func (rl *rushlink) renderInternalServerError(w http.ResponseWriter, r *http.Request, err interface{}) {
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msg := fmt.Sprintf("internal server error: %v", err)
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rl.renderError(w, r, http.StatusInternalServerError, msg)
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}
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// resolveRootURL constructs the `scheme://host` part of rushlinks public API.
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//
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// If the `--root_url` flag is set, it will return that URL.
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// Otherwise, this function will return 'https://{Host}', where `{Host}` is
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// the value provided by the client in the HTTP `Host` header. This value may
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// be invalid, but it is impossible to handle this error (because we *cannot*
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// know the real host).
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func (rl *rushlink) resolveRootURL(r *http.Request) string {
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rlHost := rl.RootURL()
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if rlHost != nil {
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// Root URL overridden by command line arguments
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return rlHost.String()
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}
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// Guess scheme
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scheme := defaultScheme
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forwardedScheme := r.Header.Get("X-Forwarded-Proto")
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switch forwardedScheme {
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case "http":
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scheme = "http"
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break
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case "https":
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scheme = "https"
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break
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}
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// Guess host
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host := r.Host
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if forwardedHost := r.Header.Get("X-Forwarded-Host"); forwardedHost != "" {
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host = forwardedHost
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}
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return scheme + "://" + host
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}
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// Try to resolve the preferred content-type for the response to this request.
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//
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// This is done by reading from the `types` argument. If one of them matches
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// the preferences supplied by the client in their Accept header, we will
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// return that one. We will take the clients preferences into account.
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//
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// Iff no match could be found, this function will return an empty string, and
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// the caller should probably respond with a 406 Not Acceptable status code.
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// Iff the Accept header was invalid, we will return an error. In this case,
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// the situation calls for a 400 Bad Request.
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func resolveResponseContentType(r *http.Request, types []string) (string, error) {
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// Ref: https://tools.ietf.org/html/rfc7231#section-5.3.2
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if len(types) == 0 {
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return "", nil
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}
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acceptHeader := strings.TrimSpace(r.Header.Get("Accept"))
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if acceptHeader == "" {
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return types[0], nil
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}
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type AcceptValue struct {
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Type string
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Subtype string
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Weight int
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}
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avStrings := strings.Split(acceptHeader, ",")
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avs := make([]AcceptValue, len(avStrings))
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for i, avString := range avStrings {
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av := AcceptValue{Weight: 1000}
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choiceParts := strings.Split(avString, ";")
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mediaRange := acceptHeaderMediaRangeRegex.FindStringSubmatch(choiceParts[0])
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if mediaRange == nil {
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return "", fmt.Errorf("bad media-range ('%v')", choiceParts[0])
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}
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av.Type = mediaRange[1]
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av.Subtype = mediaRange[2]
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// Go through the rest to see if there is a q=... parameter
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for choiceParts = choiceParts[1:]; len(choiceParts) > 0; choiceParts = choiceParts[1:] {
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// Try to parse the weight param
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weight := acceptHeaderWeight.FindStringSubmatch(choiceParts[0])
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if weight != nil {
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if weight[1] == "" {
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av.Weight = 0
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} else {
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var err error
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av.Weight, err = strconv.Atoi((weight[1] + "000")[:3])
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if err != nil {
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log.Println("error: unreachable statement")
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debug.PrintStack()
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av.Weight = 1000 // Reset to default value
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}
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}
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break
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}
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// Check if this parameter is still invalid in any case
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acceptParams := acceptHeaderAcceptParamsRegex.FindStringSubmatchIndex(choiceParts[0])
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if acceptParams == nil {
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return "", fmt.Errorf("bad accept-params ('%v')", choiceParts[0])
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}
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}
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avs[i] = av
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}
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sort.SliceStable(avs, func(i, j int) bool {
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if avs[i].Weight > avs[j].Weight {
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return true
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}
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if avs[i].Type != "*" && avs[j].Type == "*" {
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return true
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}
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if avs[i].Subtype != "*" && avs[j].Subtype == "*" {
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return true
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}
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return false
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})
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avArgs := make([]AcceptValue, len(types))
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for i, fulltype := range types {
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split := strings.Split(fulltype, "/")
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if len(split) == 1 {
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avArgs[i] = AcceptValue{Type: split[0]}
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} else {
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avArgs[i] = AcceptValue{Type: split[0], Subtype: split[1]}
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}
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}
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for _, av := range avs {
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for j, avArg := range avArgs {
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if !(av.Type == avArg.Type || av.Type == "*" || avArg.Type == "*") {
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continue
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}
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if !(av.Subtype == avArg.Subtype || av.Subtype == "*" || avArg.Subtype == "*") {
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continue
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}
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return types[j], nil
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}
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}
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return "", nil
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}
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