93 lines
3.1 KiB
Go
93 lines
3.1 KiB
Go
package gemini
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import (
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"context"
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"net/url"
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"strings"
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)
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// A Handler responds to a Gemini request.
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//
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// ServeGemini should write the response header and data to the ResponseWriter
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// and then return. Returning signals that the request is finished; it is not
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// valid to use the ResponseWriter after or concurrently with the completion
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// of the ServeGemini call.
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//
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// Handlers should not modify the provided Request.
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//
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// If ServeGemini panics, the server (the caller of ServeGemini) assumes that
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// the effect of the panic was isolated to the active request. It recovers
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// the panic, logs a stack trace to the server error log, and closes the
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// network connection. To abort a handler so the client sees an interrupted
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// response but the server doesn't log an error, panic with the value
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// ErrAbortHandler.
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type Handler interface {
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ServeGemini(context.Context, ResponseWriter, *Request)
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}
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// The HandlerFunc type is an adapter to allow the use of ordinary functions
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// as Gemini handlers. If f is a function with the appropriate signature,
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// HandlerFunc(f) is a Handler that calls f.
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type HandlerFunc func(context.Context, ResponseWriter, *Request)
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// ServeGemini calls f(ctx, w, r).
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func (f HandlerFunc) ServeGemini(ctx context.Context, w ResponseWriter, r *Request) {
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f(ctx, w, r)
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}
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// RedirectHandler returns a request handler that redirects each request it
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// receives to the given url using the given status code.
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//
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// The provided status code should be in the 3x range and is usually
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// StatusRedirect or StatusPermanentRedirect.
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func RedirectHandler(status Status, url string) Handler {
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return &redirectHandler{status, url}
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}
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type redirectHandler struct {
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status Status
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url string
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}
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func (h *redirectHandler) ServeGemini(ctx context.Context, w ResponseWriter, r *Request) {
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w.WriteHeader(h.status, h.url)
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}
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// NotFound replies to the request with a Gemini 51 not found error.
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func NotFound(ctx context.Context, w ResponseWriter, r *Request) {
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w.WriteHeader(StatusNotFound, "Not found")
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}
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// NotFoundHandler returns a simple request handler that replies to each
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// request with a “51 Not found” reply.
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func NotFoundHandler() Handler {
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return HandlerFunc(NotFound)
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}
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// StripPrefix returns a handler that serves Gemini requests by removing the
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// given prefix from the request URL's Path (and RawPath if set) and invoking
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// the handler h. StripPrefix handles a request for a path that doesn't begin
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// with prefix by replying with a Gemini 51 not found error. The prefix must
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// match exactly: if the prefix in the request contains escaped characters the
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// reply is also a Gemini 51 not found error.
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func StripPrefix(prefix string, h Handler) Handler {
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if prefix == "" {
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return h
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}
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return HandlerFunc(func(ctx context.Context, w ResponseWriter, r *Request) {
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p := strings.TrimPrefix(r.URL.Path, prefix)
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rp := strings.TrimPrefix(r.URL.RawPath, prefix)
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if len(p) < len(r.URL.Path) && (r.URL.RawPath == "" || len(rp) < len(r.URL.RawPath)) {
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r2 := new(Request)
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*r2 = *r
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r2.URL = new(url.URL)
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*r2.URL = *r.URL
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r2.URL.Path = p
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r2.URL.RawPath = rp
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h.ServeGemini(ctx, w, r2)
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} else {
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NotFound(ctx, w, r)
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}
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})
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}
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