commit 2b9de725078820701cf440ebff2bb119205c25ed
Author: Leon Richardt <leon.richardt@gmail.com>
Date:   Tue Oct 27 17:17:41 2020 +0100

    initial commit

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..391c53e
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+# Binary
+jaf
diff --git a/config.go b/config.go
new file mode 100644
index 0000000..1829906
--- /dev/null
+++ b/config.go
@@ -0,0 +1,82 @@
+package main
+
+import (
+	"bufio"
+	"log"
+	"os"
+	"strconv"
+	"strings"
+)
+
+const (
+	commentPrefix = "#"
+)
+
+type Config struct {
+	Port       int
+	LinkPrefix string
+	FileDir    string
+	LinkLength int
+}
+
+func ConfigFromFile(filePath string) (*Config, error) {
+	file, err := os.Open(filePath)
+	if err != nil {
+		return nil, err
+	}
+	defer file.Close()
+
+	oldPrefix := log.Prefix()
+	defer log.SetPrefix(oldPrefix)
+
+	log.SetPrefix("config.FromFile > ")
+
+	retval := &Config{}
+
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+
+		if strings.HasPrefix(line, commentPrefix) {
+			// Skip comments
+			continue
+		}
+
+		tokens := strings.Split(line, ": ")
+		if len(tokens) != 2 {
+			log.Printf("unexpected line: \"%s\", ignoring\n", line)
+			continue
+		}
+
+		key, val := strings.TrimSpace(tokens[0]), strings.TrimSpace(tokens[1])
+
+		switch key {
+		case "Port":
+			parsed, err := strconv.Atoi(val)
+			if err != nil {
+				return nil, err
+			}
+
+			retval.Port = parsed
+		case "LinkPrefix":
+			retval.LinkPrefix = val
+		case "FileDir":
+			retval.FileDir = val
+		case "LinkLength":
+			parsed, err := strconv.Atoi(val)
+			if err != nil {
+				return nil, err
+			}
+
+			retval.LinkLength = parsed
+		default:
+			log.Printf("unexpected key: \"%s\", ignoring\n", key)
+		}
+	}
+
+	if err := scanner.Err(); err != nil {
+		return nil, err
+	}
+
+	return retval, nil
+}
diff --git a/config_test.go b/config_test.go
new file mode 100644
index 0000000..5e7a096
--- /dev/null
+++ b/config_test.go
@@ -0,0 +1,29 @@
+package main
+
+import (
+	"testing"
+)
+
+func assertEqualInt(have int, want int, t *testing.T) {
+	if have != want {
+		t.Errorf("have: %d, want: %d\n", have, want)
+	}
+}
+
+func assertEqualString(have string, want string, t *testing.T) {
+	if have != want {
+		t.Errorf("have: %s, want: %s\n", have, want)
+	}
+}
+
+func TestConfigFromFile(t *testing.T) {
+	config, err := ConfigFromFile("example.conf")
+	if err != nil {
+		panic(err)
+	}
+
+	assertEqualInt(config.Port, 4711, t)
+	assertEqualString(config.LinkPrefix, "https://jaf.example.com/", t)
+	assertEqualString(config.FileDir, "/var/www/jaf.example.com/", t)
+	assertEqualInt(config.LinkLength, 5, t)
+}
diff --git a/example.conf b/example.conf
new file mode 100644
index 0000000..46ca837
--- /dev/null
+++ b/example.conf
@@ -0,0 +1,5 @@
+Port:       4711
+# a comment
+LinkPrefix: https://jaf.example.com/
+FileDir:    /var/www/jaf.example.com/
+LinkLength: 5
diff --git a/jaf.go b/jaf.go
new file mode 100644
index 0000000..cd62e39
--- /dev/null
+++ b/jaf.go
@@ -0,0 +1,65 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"math/rand"
+	"net/http"
+	"time"
+)
+
+const allowedChars = "0123456789ABCDEFGHIJKLMNOPQRTSUVWXYZabcdefghijklmnopqrstuvwxyz"
+
+var (
+	savedFileNames = NewSet()
+	config         Config
+)
+
+type parameters struct {
+	configFile string
+}
+
+func parseParams() *parameters {
+	configFile := flag.String("configFile", "jaf.conf", "path to config file")
+	flag.Parse()
+
+	retval := &parameters{}
+	retval.configFile = *configFile
+	return retval
+}
+
+func main() {
+	rand.Seed(time.Now().UnixNano())
+	log.SetPrefix("jaf > ")
+
+	params := parseParams()
+
+	// Read config
+	config, err := ConfigFromFile(params.configFile)
+	if err != nil {
+		log.Fatalf("could not read config file: %s\n", err.Error())
+	}
+
+	files, err := ioutil.ReadDir(config.FileDir)
+	if err != nil {
+		log.Fatalf("could not read file root %s: %s\n", config.FileDir, err.Error())
+	}
+
+	// Cache taken file names on start-up
+	for _, fileInfo := range files {
+		savedFileNames.Insert(fileInfo.Name())
+	}
+
+	// Start server
+	uploadServer := &http.Server{
+		ReadTimeout:  30 * time.Second,
+		WriteTimeout: 30 * time.Second,
+		Addr:         fmt.Sprintf(":%d", config.Port),
+	}
+
+	log.Printf("starting jaf on port %d\n", config.Port)
+	http.Handle("/upload", &uploadHandler{config: config})
+	uploadServer.ListenAndServe()
+}
diff --git a/set.go b/set.go
new file mode 100644
index 0000000..547bcb0
--- /dev/null
+++ b/set.go
@@ -0,0 +1,34 @@
+package main
+
+type Set struct {
+	_map map[interface{}]struct{}
+}
+
+func NewSet() *Set {
+	set := &Set{}
+	set._map = make(map[interface{}]struct{})
+	return set
+}
+
+func (set *Set) Contains(value interface{}) bool {
+	_, ok := set._map[value]
+	return ok
+}
+
+func (set *Set) Insert(value interface{}) bool {
+	if set.Contains(value) {
+		return false
+	}
+
+	set._map[value] = struct{}{}
+	return true
+}
+
+func (set *Set) Remove(value interface{}) bool {
+	if !set.Contains(value) {
+		return false
+	}
+
+	delete(set._map, value)
+	return true
+}
diff --git a/set_test.go b/set_test.go
new file mode 100644
index 0000000..56282a8
--- /dev/null
+++ b/set_test.go
@@ -0,0 +1,75 @@
+package main
+
+import (
+	"math/rand"
+	"testing"
+	"time"
+)
+
+func TestContains(t *testing.T) {
+	set := NewSet()
+
+	// Oracle testing
+	dummy := 0
+	in := set.Contains(dummy)
+	if in {
+		t.Errorf("oracle > set.Contains(%d) = true before insertion", dummy)
+	}
+
+	set.Insert(dummy)
+	in = set.Contains(dummy)
+	if !in {
+		t.Errorf("oracle > set.Contains(%d) = false after insertion", dummy)
+	}
+
+	// Property testing
+	rand.Seed(time.Now().UnixNano())
+	const reps = 1000
+	for i := 0; i < reps; i++ {
+		lastInsert := rand.Int()
+		set.Insert(lastInsert)
+
+		in = set.Contains(lastInsert)
+
+		if !in {
+			t.Errorf("property > set.Contains(%d) = false after insertion", dummy)
+		}
+	}
+}
+
+func TestInsert(t *testing.T) {
+	set := NewSet()
+
+	// Oracle testing
+	dummy := 0
+	innovative := set.Insert(dummy)
+
+	if !innovative {
+		t.Errorf("oracle > set.Insert(%d) = false but was innovative", dummy)
+	}
+
+	in := set.Contains(dummy)
+	if !in {
+		t.Errorf("oracle > set.Contains(%d) = false after insertion", dummy)
+	}
+
+	// Duplicate insertion should return false
+	innovative = set.Insert(dummy)
+	if innovative {
+		t.Errorf("oracle > set.Insert(%d) = true but was not innovative", dummy)
+	}
+
+	// Property testing
+	rand.Seed(time.Now().UnixNano())
+	const reps = 1000
+	for i := 0; i < reps; i++ {
+		val := rand.Int()
+
+		inBefore := set.Contains(val)
+		innovative = set.Insert(val)
+
+		if inBefore && innovative {
+			t.Errorf("property > included value reported as innovative")
+		}
+	}
+}
diff --git a/uploadhandler.go b/uploadhandler.go
new file mode 100644
index 0000000..9fc4830
--- /dev/null
+++ b/uploadhandler.go
@@ -0,0 +1,91 @@
+package main
+
+import (
+	"io"
+	"log"
+	"math/rand"
+	"mime/multipart"
+	"net/http"
+	"os"
+	"strings"
+)
+
+type uploadHandler struct {
+	config *Config
+}
+
+func (h *uploadHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	defer r.Body.Close()
+	log.Println("request received from " + r.RemoteAddr)
+
+	uploadFile, header, err := r.FormFile("file")
+	if err != nil {
+		http.Error(w, "could not read uploaded file: "+err.Error(), http.StatusBadRequest)
+		log.Println("    could not read uploaded file: " + err.Error())
+		return
+	}
+	defer uploadFile.Close()
+
+	originalName, fileExtension := splitFileName(header.Filename)
+	log.Println("    received file: " + originalName)
+
+	// Find an unused file name
+	fileID := createRandomFileName(h.config.LinkLength)
+	for ; savedFileNames.Contains(fileID); fileID = createRandomFileName(h.config.LinkLength) {
+	}
+	log.Println("    generated random id: " + fileID)
+
+	fullFileName := fileID + fileExtension
+	savePath := h.config.FileDir + fullFileName
+	link := h.config.LinkPrefix + fullFileName
+
+	err = saveFile(uploadFile, savePath)
+	if err != nil {
+		http.Error(w, "could not save file: "+err.Error(), http.StatusInternalServerError)
+		log.Println("    could not save file: " + err.Error())
+		return
+	}
+	savedFileNames.Insert(fullFileName)
+	log.Println("    saved file as: " + fullFileName)
+
+	// Implicitly means code 200
+	w.Write([]byte(link))
+}
+
+func saveFile(data multipart.File, name string) error {
+	file, err := os.Create(name)
+	if err != nil {
+		return err
+	}
+
+	defer file.Close()
+
+	_, err = io.Copy(file, data)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func createRandomFileName(length int) string {
+	chars := make([]byte, length)
+
+	for i := 0; i < length; i++ {
+		index := rand.Intn(len(allowedChars))
+		chars[i] = allowedChars[index]
+	}
+
+	return string(chars)
+}
+
+func splitFileName(name string) (string, string) {
+	extIndex := strings.LastIndex(name, ".")
+
+	if extIndex == -1 {
+		// No dot at all
+		return name, ""
+	}
+
+	return name[:extIndex], name[extIndex:]
+}