feat: improve content type handling

Parse content type for the file from multipart form data request

Add security headers to avoid malicious use of the application when
serving an html file

README.md

@@ -43,6 +43,9 @@ POSTGRES_URL="postgres://postgres:password@localhost:5432/sekret_link_test?sslmo
 
 ### Send and receive data
 ```sh
-curl -v --data-binary @go.mod localhost:8080/api/ | xargs -I {} curl localhost:8080{}
+curl -v -H 'content-type: text/plain' --data-binary @go.mod localhost:8080/api/ | xargs -I {} curl localhost:8080{}
 ```
 
+```sh
+curl -v -F 'secret=@README.md;type=text/x-markdown' localhost:8080/api/ | xargs -I {} curl -v localhost:8080{}
+```

internal/api/createentry.go

@@ -3,6 +3,7 @@ package api
 import (
 	"context"
 	"errors"
+	"log"
 	"net/http"
 	"time"
 
@@ -60,11 +61,9 @@ func (c CreateHandler) handle(w http.ResponseWriter, r *http.Request) error {
 		return errors.Join(ErrRequestParseError, err)
 	}
 
-	contentType := r.Header.Get("Content-Type")
-
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
-	entry, key, err := c.entryManager.CreateEntry(ctx, contentType, data.Body, data.MaxReads, data.Expiration)
+	entry, key, err := c.entryManager.CreateEntry(ctx, data.ContentType, data.Body, data.MaxReads, data.Expiration)
 
 	if err != nil {
 		return err
@@ -81,6 +80,7 @@ func (c CreateHandler) Handle(w http.ResponseWriter, r *http.Request) {
 	err := c.handle(w, r)
 
 	if err != nil {
+		log.Println("create error", err)
 		c.view.RenderError(w, r, err)
 	}
 }

internal/api/createentry_test.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"errors"
+	"fmt"
 	"net/http"
 	"net/http/httptest"
 	"testing"
@@ -38,6 +39,7 @@ func (m *MockEntryManager) CreateEntry(
 	maxReads int,
 	expiration time.Duration,
 ) (*services.EntryMeta, key.Key, error) {
+	fmt.Println("content type", contentType)
 	args := m.Called(ctx, contentType, body, maxReads, expiration)
 
 	if args.Get(1) == nil {
@@ -72,7 +74,9 @@ func Test_CreateEntryHandle(t *testing.T) {
 	request.Header.Set("Content-Type", "text/plain")
 	response := httptest.NewRecorder()
 
-	parser.On("Parse", request).Return(&parsers.CreateEntryRequestData{}, nil)
+	parser.On("Parse", request).Return(&parsers.CreateEntryRequestData{
+		ContentType: "text/plain",
+	}, nil)
 
 	retKey, err := key.NewGeneratedKey()
 	if err != nil {
@@ -126,7 +130,9 @@ func Test_CreateEntryHandleError(t *testing.T) {
 	request.Header.Set("Content-Type", "text/plain")
 	response := httptest.NewRecorder()
 
-	parser.On("Parse", request).Return(&parsers.CreateEntryRequestData{}, nil)
+	parser.On("Parse", request).Return(&parsers.CreateEntryRequestData{
+		ContentType: "text/plain",
+	}, nil)
 	k, err := key.NewGeneratedKey()
 	assert.NoError(t, err)
 	entryManager.On("CreateEntry", mock.Anything, "text/plain", mock.Anything, mock.Anything, mock.Anything).Return(&services.EntryMeta{}, *k, errors.New("error"))

internal/parsers/createentry.go

@@ -15,37 +15,41 @@ type CreateEntryParser struct {
 }
 
 type CreateEntryRequestData struct {
-	Body       []byte
-	Expiration time.Duration
-	MaxReads   int
+	ContentType string
+	Body        []byte
+	Expiration  time.Duration
+	MaxReads    int
 }
 
 func NewCreateEntryParser(maxExpireSeconds int) CreateEntryParser {
 	return CreateEntryParser{maxExpireSeconds: maxExpireSeconds}
 }
 
-func parseMultiForm(r *http.Request) ([]byte, error) {
+func parseMultiForm(r *http.Request) ([]byte, string, error) {
 	err := r.ParseMultipartForm(1024 * 1024)
 	if err != nil {
-		return nil, err
+		return nil, "", err
 	}
 
 	secret := r.PostForm.Get("secret")
 	if secret != "" {
 		body := []byte(secret)
-		return body, nil
+		return body, "text/plain", nil
 	}
 
-	file, _, err := r.FormFile("secret")
+	file, header, err := r.FormFile("secret")
+	contentType := header.Header.Get("Content-Type")
 
 	if err != nil {
-		return nil, err
+		return nil, "", err
 	}
 
-	return io.ReadAll(file)
+	data, err := io.ReadAll(file)
+
+	return data, contentType, err
 }
 
-func getBody(r *http.Request) ([]byte, error) {
+func getContentType(r *http.Request) string {
 	ct := r.Header.Get("content-type")
 	if ct == "" {
 		ct = "application/octet-stream"
@@ -54,14 +58,20 @@ func getBody(r *http.Request) ([]byte, error) {
 	ct, _, err := mime.ParseMediaType(ct)
 
 	if err != nil {
-		return nil, err
+		return "application/octet-stream"
 	}
 
+	return ct
+}
+
+func getContent(r *http.Request) ([]byte, string, error) {
+	ct := getContentType(r)
 	switch {
 	case ct == "multipart/form-data":
 		return parseMultiForm(r)
 	default:
-		return io.ReadAll(r.Body)
+		data, err := io.ReadAll(r.Body)
+		return data, ct, err
 	}
 }
 
@@ -98,7 +108,7 @@ func (c CreateEntryParser) getSecretMaxReads(r *http.Request) (int, error) {
 }
 
 func (c CreateEntryParser) Parse(r *http.Request) (*CreateEntryRequestData, error) {
-	body, err := getBody(r)
+	body, contentType, err := getContent(r)
 
 	if err != nil {
 		return nil, err
@@ -121,9 +131,10 @@ func (c CreateEntryParser) Parse(r *http.Request) (*CreateEntryRequestData, erro
 	}
 
 	return &CreateEntryRequestData{
-		Body:       body,
-		Expiration: expiration,
-		MaxReads:   maxReads,
+		ContentType: contentType,
+		Body:        body,
+		Expiration:  expiration,
+		MaxReads:    maxReads,
 	}, nil
 
 }

internal/views/entryread.go

@@ -45,12 +45,17 @@ func NewEntryReadView() EntryReadView {
 
 func (e EntryReadView) Render(w http.ResponseWriter, r *http.Request, response EntryReadResponse) {
 	if r.Header.Get("Accept") == "application/json" {
+		w.Header().Add("Content-Type", "application/json")
 		if err := json.NewEncoder(w).Encode(response); err != nil {
 			log.Println("JSON encode failed", err)
 		}
 	} else {
 		if response.ContentType != "" {
-			w.Header().Add("Content-Type", response.ContentType)
+			headers := w.Header()
+			headers.Add("Content-Type", response.ContentType)
+			headers.Add("X-Frame-Options", "deny")
+			headers.Add("Content-Security-Policy", "default-src 'none'; style-src 'unsafe-inline'; img-src 'self' data:; frame-ancestors 'none'; upgrade-insecure-requests; sandbox;")
+
 		}
 		w.WriteHeader(http.StatusOK)
 		_, err := w.Write([]byte(response.Data))