basic file uploader

.gitignore

@@ -0,0 +1 @@
+uploads

handlers.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"io"
+	"net/http"
+	"os"
+	"path/filepath"
+)
+
+const MAX_UPLOAD_SIZE = 5 * 1024 * 1024 // 5MB
+
+func upload(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+
+	r.Body = http.MaxBytesReader(w, r.Body, MAX_UPLOAD_SIZE)
+	if err := r.ParseMultipartForm(MAX_UPLOAD_SIZE); err != nil {
+		http.Error(w, "file too big. must be under 5MB", http.StatusBadRequest)
+		return
+	}
+
+	file, fileHeader, err := r.FormFile("file")
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+	defer file.Close()
+
+	// make buffer used to detect content type
+	buff := make([]byte, 512)
+	if _, err := file.Read(buff); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	filetype := http.DetectContentType(buff)
+	if filetype != "image/jpeg" && filetype != "image/png" {
+		http.Error(w, "invalid format. only jpeg and png are accepted", http.StatusBadRequest)
+		return
+	}
+
+	// seek back to beginning to get whole file
+	if _, err := file.Seek(0, io.SeekStart); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	dst, err := os.Create(filepath.Join(".", "uploads", fileHeader.Filename))
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	defer dst.Close()
+
+	_, err = io.Copy(dst, file)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+}

justfile

@@ -1,2 +1,2 @@
 run:
-  go run ./cmd/uploadr
+  go run .

cmd/uploadr/main.go → main.go

@@ -11,8 +11,15 @@ import (
 )
 
 func main() {
-	logger := logrus.New()
+	// create directory to hold uploads
+	err := os.MkdirAll("./uploads", os.ModePerm)
+	if err != nil {
+		logrus.WithError(err).Fatal("unable to create the upload directory")
+		return
+	}
+
 	router := http.NewServeMux()
+	router.HandleFunc("/upload", upload)
 	server := http.Server{
 		Addr:    ":8080",
 		Handler: router,
@@ -29,18 +36,18 @@ func main() {
 		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 		defer cancel()
 		if err := server.Shutdown(ctx); err != nil {
-			logger.WithError(err).Fatal("graceful shutdown failed")
+			logrus.WithError(err).Fatal("graceful shutdown failed")
 		}
 		close(shutdownComplete)
 	}()
 
-	logger.Info("server started on :8080")
+	logrus.Info("server started on :8080")
 	if err := server.ListenAndServe(); err != http.ErrServerClosed {
-		logger.WithError(err).Fatal("server unable to start")
+		logrus.WithError(err).Fatal("server unable to start")
 	}
-	logger.Info("server exiting")
+	logrus.Info("server exiting")
 
 	<-shutdownComplete
 
-	logger.Info("server gracefully shut down")
+	logrus.Info("server gracefully shut down")
 }