Cleanup session handling and improve oidc

api/web.go

@@ -0,0 +1,175 @@
+package api
+
+import (
+	"context"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"github.com/coreos/go-oidc/v3/oidc"
+	"github.com/gorilla/sessions"
+	"github.com/patrickmn/go-cache"
+	"golang.org/x/oauth2"
+	"log"
+	"math/rand"
+	"net/http"
+	"strings"
+	"time"
+)
+
+const (
+	RdpGwSession = "RDPGWSESSION"
+	PAAToken     = "PAAToken"
+)
+
+type Config struct {
+	SessionKey     []byte
+	TokenCache     *cache.Cache
+	OAuth2Config   *oauth2.Config
+	store          *sessions.CookieStore
+	TokenVerifier  *oidc.IDTokenVerifier
+	stateStore     *cache.Cache
+	Hosts          []string
+	GatewayAddress string
+}
+
+func (c *Config) NewApi() {
+	if len(c.SessionKey) < 32 {
+		log.Fatal("Session key too small")
+	}
+	if len(c.Hosts) < 1 {
+		log.Fatal("Not enough hosts to connect to specified")
+	}
+	c.store = sessions.NewCookieStore(c.SessionKey)
+	c.stateStore = cache.New(time.Minute*2, 5*time.Minute)
+}
+
+func (c *Config) HandleCallback(w http.ResponseWriter, r *http.Request) {
+	state := r.URL.Query().Get("state")
+	s, found := c.stateStore.Get(state)
+	if !found {
+		http.Error(w, "unknown state", http.StatusBadRequest)
+		return
+	}
+	url := s.(string)
+
+	ctx := context.Background()
+	oauth2Token, err := c.OAuth2Config.Exchange(ctx, r.URL.Query().Get("code"))
+	if err != nil {
+		http.Error(w, "Failed to exchange token: "+err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	rawIDToken, ok := oauth2Token.Extra("id_token").(string)
+	if !ok {
+		http.Error(w, "No id_token field in oauth2 token.", http.StatusInternalServerError)
+		return
+	}
+	idToken, err := c.TokenVerifier.Verify(ctx, rawIDToken)
+	if err != nil {
+		http.Error(w, "Failed to verify ID Token: "+err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	resp := struct {
+		OAuth2Token   *oauth2.Token
+		IDTokenClaims *json.RawMessage // ID Token payload is just JSON.
+	}{oauth2Token, new(json.RawMessage)}
+
+	if err := idToken.Claims(&resp.IDTokenClaims); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	var data map[string]interface{}
+	if err := json.Unmarshal(*resp.IDTokenClaims, &data); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	seed := make([]byte, 16)
+	rand.Read(seed)
+	token := hex.EncodeToString(seed)
+
+	session, err := c.store.Get(r, RdpGwSession)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	session.Values[PAAToken] = token
+
+	if err = session.Save(r, w); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+	}
+	c.TokenCache.Set(token, data, cache.DefaultExpiration)
+
+	http.Redirect(w, r, url, http.StatusFound)
+}
+
+func (c *Config) Authenticated(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		session, err := c.store.Get(r, RdpGwSession)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+
+		found := false
+		token := session.Values[PAAToken]
+		if token != nil {
+			_, found = c.TokenCache.Get(token.(string))
+		}
+
+		if !found {
+			seed := make([]byte, 16)
+			rand.Read(seed)
+			state := hex.EncodeToString(seed)
+			c.stateStore.Set(state, r.RequestURI, cache.DefaultExpiration)
+			http.Redirect(w, r, c.OAuth2Config.AuthCodeURL(state), http.StatusFound)
+			return
+		}
+
+		next.ServeHTTP(w, r)
+	})
+}
+
+func (c *Config) HandleDownload(w http.ResponseWriter, r *http.Request) {
+	session, err := c.store.Get(r, RdpGwSession)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	token := session.Values[PAAToken].(string)
+	data, found := c.TokenCache.Get(token)
+	if found == false {
+		// This shouldnt happen if the Authenticated handler is used to wrap this func
+		log.Printf("Found expired or non existent session: %s", token)
+		http.Error(w, errors.New("cannot find token").Error(), http.StatusInternalServerError)
+		return
+	}
+
+	// do a round robin selection for now
+	rand.Seed(time.Now().Unix())
+	var host = c.Hosts[rand.Intn(len(c.Hosts))]
+	for k, v := range data.(map[string]interface{}) {
+		if val, ok := v.(string); ok == true {
+			host = strings.Replace(host, "{{ "+k+" }}", val, 1)
+		}
+	}
+
+	// authenticated
+	seed := make([]byte, 16)
+	rand.Read(seed)
+	fn := hex.EncodeToString(seed) + ".rdp"
+
+	w.Header().Set("Content-Disposition", "attachment; filename="+fn)
+	w.Header().Set("Content-Type", "application/x-rdp")
+	http.ServeContent(w, r, fn, time.Now(), strings.NewReader(
+		"full address:s:"+host+"\r\n"+
+			"gatewayhostname:s:"+c.GatewayAddress+"\r\n"+
+			"gatewaycredentialssource:i:5\r\n"+
+			"gatewayusagemethod:i:1\r\n"+
+			"gatewayprofileusagemethod:i:1\r\n"+
+			"gatewayaccesstoken:s:"+token+"\r\n"))
+}