f19619ef9f
This commit adds a new environment package that manages all calls to the underlying operating system.
133 lines
3.5 KiB
Go
133 lines
3.5 KiB
Go
package control
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import (
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"encoding/json"
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"fmt"
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"net/http"
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"strings"
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"github.com/tkw1536/goprogram/stream"
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)
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// self returns the handler for the self overrides
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func (control Control) self(io stream.IOStream) (redirect Redirect, err error) {
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// open the overrides file
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overrides, err := control.Environment.Open(control.Config.SelfOverridesFile)
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io.Printf("loading overrides from %q\n", control.Config.SelfOverridesFile)
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if err != nil {
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return redirect, err
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}
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defer overrides.Close()
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// decode the overrides file
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if err := json.NewDecoder(overrides).Decode(&redirect.Overrides); err != nil {
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return redirect, err
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}
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if redirect.Overrides == nil {
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redirect.Overrides = make(map[string]string)
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}
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redirect.Overrides[""] = control.Config.SelfRedirect.String()
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// create a redirect server
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redirect.Fallback, err = control.selfFallback()
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if err != nil {
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return redirect, err
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}
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redirect.Absolute = false
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redirect.Permanent = false
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// and return!
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return redirect, nil
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}
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func (control *Control) selfFallback() (http.Handler, error) {
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return http.HandlerFunc(control.serveFallback), nil
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}
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var notFoundText = []byte("not found")
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func (control *Control) serveFallback(w http.ResponseWriter, r *http.Request) {
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slug := control.Config.SlugFromHost(r.Host)
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if slug == "" {
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w.WriteHeader(http.StatusNotFound)
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w.Write(notFoundText)
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return
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}
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if ok, _ := control.Instances.Has(slug); !ok {
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w.WriteHeader(http.StatusNotFound)
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fmt.Fprintf(w, "WissKI %q not found\n", slug)
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return
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}
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w.WriteHeader(http.StatusBadGateway)
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fmt.Fprintf(w, "WissKI %q is currently offline\n", slug)
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}
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// Redirect implements a redirect server that redirects all requests.
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// It implements http.Handler.
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type Redirect struct {
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// Target is the target URL to redirect to.
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Target string
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// Fallback is used when target is the empty string.
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Fallback http.Handler
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// Absolute determines if the request path should be appended to the target URL when redirecting.
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// By default this path is always appended, set Absolute to true to prevent this.
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Absolute bool
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// Overrides is a map from paths to URLs that should override the default target.
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Overrides map[string]string
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// Permanent determines if the redirect responses issued should return
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// Permanent Redirect (Status Code 308) or Temporary Redirect (Status Code 307).
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Permanent bool
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}
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// Redirect determines the redirect URL for a specific incoming request
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// If it returns the empty string, the fallback is used.
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func (redirect Redirect) Redirect(r *http.Request) string {
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// if we have an override for this URL, use it immediatly
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url := strings.TrimSuffix(r.URL.Path, "/")
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if override, ok := redirect.Overrides[url]; ok {
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return override
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}
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if redirect.Target == "" {
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return ""
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}
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// if we are in absolute redirect mode, always return the absolute URL
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if redirect.Absolute {
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return redirect.Target
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}
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// return the target + the redirected URL
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dest := strings.TrimSuffix(redirect.Target, "/") + r.URL.Path
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if len(r.URL.RawQuery) > 0 {
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dest += "?" + r.URL.RawQuery
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}
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return dest
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}
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// ServeHTTP implements the http.Handler interface and redirects a single request to redirect.Target.
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func (redirect Redirect) ServeHTTP(w http.ResponseWriter, r *http.Request) {
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dest := redirect.Redirect(r)
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if dest == "" {
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redirect.Fallback.ServeHTTP(w, r)
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return
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}
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// determine if we are temporary or permanent redirect
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status := http.StatusTemporaryRedirect
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if redirect.Permanent {
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status = http.StatusPermanentRedirect
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}
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// and do the redirect
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http.Redirect(w, r, dest, status)
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}
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