forked from TrueCloudLab/certificates
125 lines
2.8 KiB
Go
125 lines
2.8 KiB
Go
// Package render implements functionality related to response rendering.
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package render
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import (
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"bytes"
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"encoding/json"
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"errors"
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"net/http"
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"google.golang.org/protobuf/encoding/protojson"
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"google.golang.org/protobuf/proto"
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"github.com/smallstep/certificates/api/log"
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)
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// JSON is shorthand for JSONStatus(w, v, http.StatusOK).
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func JSON(w http.ResponseWriter, v interface{}) {
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JSONStatus(w, v, http.StatusOK)
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}
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// JSONStatus marshals v into w. It additionally sets the status code of
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// w to the given one.
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//
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// JSONStatus sets the Content-Type of w to application/json unless one is
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// specified.
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func JSONStatus(w http.ResponseWriter, v interface{}, status int) {
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var b bytes.Buffer
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if err := json.NewEncoder(&b).Encode(v); err != nil {
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panic(err)
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}
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setContentTypeUnlessPresent(w, "application/json")
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w.WriteHeader(status)
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_, _ = b.WriteTo(w)
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log.EnabledResponse(w, v)
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}
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// ProtoJSON is shorthand for ProtoJSONStatus(w, m, http.StatusOK).
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func ProtoJSON(w http.ResponseWriter, m proto.Message) {
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ProtoJSONStatus(w, m, http.StatusOK)
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}
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// ProtoJSONStatus writes the given value into the http.ResponseWriter and the
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// given status is written as the status code of the response.
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func ProtoJSONStatus(w http.ResponseWriter, m proto.Message, status int) {
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b, err := protojson.Marshal(m)
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if err != nil {
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panic(err)
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}
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setContentTypeUnlessPresent(w, "application/json")
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w.WriteHeader(status)
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_, _ = w.Write(b)
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}
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func setContentTypeUnlessPresent(w http.ResponseWriter, contentType string) {
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const header = "Content-Type"
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h := w.Header()
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if _, ok := h[header]; !ok {
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h.Set(header, contentType)
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}
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}
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// RenderableError is the set of errors that implement the basic Render method.
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//
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// Errors that implement this interface will use their own Render method when
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// being rendered into responses.
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type RenderableError interface {
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error
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Render(http.ResponseWriter)
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}
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// Error marshals the JSON representation of err to w. In case err implements
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// RenderableError its own Render method will be called instead.
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func Error(w http.ResponseWriter, err error) {
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log.Error(w, err)
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var r RenderableError
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if errors.As(err, &r) {
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r.Render(w)
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return
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}
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JSONStatus(w, err, statusCodeFromError(err))
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}
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// StatusCodedError is the set of errors that implement the basic StatusCode
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// function.
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//
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// Errors that implement this interface will use the code reported by StatusCode
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// as the HTTP response code when being rendered by this package.
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type StatusCodedError interface {
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error
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StatusCode() int
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}
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func statusCodeFromError(err error) (code int) {
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code = http.StatusInternalServerError
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type causer interface {
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Cause() error
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}
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for err != nil {
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var sc StatusCodedError
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if errors.As(err, &sc) {
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code = sc.StatusCode()
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break
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}
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var c causer
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if !errors.As(err, &c) {
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break
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}
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err = c.Cause()
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}
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return
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}
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