08: Lösungen

web/08/labor/08_loesungen/02/go.mod

@@ -0,0 +1,5 @@
+module uebung03/cookies
+
+go 1.24.5
+
+require github.com/google/uuid v1.6.0

web/08/labor/08_loesungen/02/go.sum

@@ -0,0 +1,2 @@
+github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
+github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=

web/08/labor/08_loesungen/02/uebung02.go

@@ -0,0 +1,46 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+
+	"github.com/google/uuid"
+)
+
+func createCookie(w http.ResponseWriter, r *http.Request) {
+	uuid := uuid.New().String()
+	cookie := &http.Cookie{
+		Name:  "keks",
+		Value: uuid,
+	}
+	http.SetCookie(w, cookie)
+	fmt.Fprintf(w, "Cookie gesetzt: keks = %s\n", uuid)
+}
+
+func showCookie(w http.ResponseWriter, r *http.Request) {
+	cookie, err := r.Cookie("keks")
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+	fmt.Fprintf(w, "Cookie gefunden: keks = %s\n", cookie.Value)
+}
+
+func deleteCookie(w http.ResponseWriter, r *http.Request) {
+	cookie, err := r.Cookie("keks")
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+	cookie.MaxAge = -1
+	http.SetCookie(w, cookie)
+	fmt.Fprintf(w, "Cookie gelöscht.\n")
+}
+
+func main() {
+	http.HandleFunc("/create-cookie", createCookie)
+	http.HandleFunc("/show-cookie", showCookie)
+	http.HandleFunc("/delete-cookie", deleteCookie)
+	log.Fatal(http.ListenAndServe("localhost:8080", nil))
+}

web/08/labor/08_loesungen/03/go.mod

@@ -0,0 +1,5 @@
+module uebung04/sessions
+
+go 1.24.5
+
+require github.com/google/uuid v1.6.0

web/08/labor/08_loesungen/03/go.sum

@@ -0,0 +1,2 @@
+github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
+github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=

web/08/labor/08_loesungen/03/uebung03.go

@@ -0,0 +1,75 @@
+package main
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+	"sync"
+
+	"github.com/google/uuid"
+)
+
+type UserData struct {
+	Username string `json:"username"`
+	Nickname string `json:"nickname"`
+	Admin    bool   `json:"admin"`
+}
+
+var (
+	sessions = make(map[string]UserData)
+	mu       sync.Mutex
+)
+
+func checkSessionID(r *http.Request) (string, error) {
+	cookie, err := r.Cookie("session_id")
+	if err != nil {
+		return "", errors.New("keine session-ID")
+	}
+	return cookie.Value, nil
+}
+
+func signup(w http.ResponseWriter, r *http.Request) {
+	var user UserData
+	err := json.NewDecoder(r.Body).Decode(&user)
+	if err != nil || user.Nickname == "" || user.Username == "" {
+		http.Error(w, "Daten konnten nicht verarbeitet werden.", http.StatusBadRequest)
+		return
+	}
+
+	newID := uuid.New().String()
+	newCookie := http.Cookie{
+		Name:  "session_id",
+		Value: newID,
+	}
+	http.SetCookie(w, &newCookie)
+
+	mu.Lock()
+	sessions[newID] = user
+	mu.Unlock()
+}
+
+func whoami(w http.ResponseWriter, r *http.Request) {
+	sessionID, err := checkSessionID(r)
+	if err != nil {
+		fmt.Fprintf(w, "Du bist noch niemand.")
+	} else {
+		mu.Lock()
+		user, ok := sessions[sessionID]
+		mu.Unlock()
+		if ok {
+			fmt.Fprintf(w, "Hallo %s!\n", user.Nickname)
+			if user.Admin {
+				fmt.Fprintln(w, "Du bist als Admin registriert.")
+			} else {
+				fmt.Fprintln(w, "Du bist nicht als Admin registriert.")
+			}
+		}
+	}
+}
+
+func main() {
+	http.HandleFunc("/signup", signup)
+	http.HandleFunc("/whoami", whoami)
+	http.ListenAndServe("localhost:8080", nil)
+}

web/08/labor/08_loesungen/uebung01.go

@@ -0,0 +1,20 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+)
+
+func loginFunc(w http.ResponseWriter, r *http.Request) {
+	fmt.Fprintln(w, "Sie wurden erfolgreich eingeloggt.")
+}
+
+func logoutFunc(w http.ResponseWriter, r *http.Request) {
+	fmt.Fprintln(w, "Sie wurden erfolgreich ausgeloggt")
+}
+
+func main() {
+	http.HandleFunc("/login", loginFunc)
+	http.HandleFunc("/logout", logoutFunc)
+	http.ListenAndServe("localhost:8080", nil)
+}