Refactor context out of API packages (#8755)

* Refactor context out of API packages

* Update function names per feedback

* Move webhook handlers to web and fix web tests

* Move more webhook tests out of api package

* Fix static handler

web/handlers.go

@@ -0,0 +1,158 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package web
+
+import (
+	"fmt"
+	"net/http"
+	"time"
+
+	"github.com/mattermost/mattermost-server/app"
+	"github.com/mattermost/mattermost-server/mlog"
+	"github.com/mattermost/mattermost-server/model"
+	"github.com/mattermost/mattermost-server/utils"
+)
+
+func (w *Web) NewHandler(h func(*Context, http.ResponseWriter, *http.Request)) http.Handler {
+	return &Handler{
+		App:            w.App,
+		HandleFunc:     h,
+		RequireSession: false,
+		TrustRequester: false,
+		RequireMfa:     false,
+		IsStatic:       false,
+	}
+}
+
+func (w *Web) NewStaticHandler(h func(*Context, http.ResponseWriter, *http.Request)) http.Handler {
+	return &Handler{
+		App:            w.App,
+		HandleFunc:     h,
+		RequireSession: false,
+		TrustRequester: false,
+		RequireMfa:     false,
+		IsStatic:       true,
+	}
+}
+
+type Handler struct {
+	App            *app.App
+	HandleFunc     func(*Context, http.ResponseWriter, *http.Request)
+	RequireSession bool
+	TrustRequester bool
+	RequireMfa     bool
+	IsStatic       bool
+}
+
+func (h Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	now := time.Now()
+	mlog.Debug(fmt.Sprintf("%v - %v", r.Method, r.URL.Path))
+
+	c := &Context{}
+	c.App = h.App
+	c.T, _ = utils.GetTranslationsAndLocale(w, r)
+	c.RequestId = model.NewId()
+	c.IpAddress = utils.GetIpAddress(r)
+	c.Params = ParamsFromRequest(r)
+
+	token, tokenLocation := app.ParseAuthTokenFromRequest(r)
+
+	// CSRF Check
+	if tokenLocation == app.TokenLocationCookie && h.RequireSession && !h.TrustRequester {
+		if r.Header.Get(model.HEADER_REQUESTED_WITH) != model.HEADER_REQUESTED_WITH_XML {
+			c.Err = model.NewAppError("ServeHTTP", "api.context.session_expired.app_error", nil, "token="+token+" Appears to be a CSRF attempt", http.StatusUnauthorized)
+			token = ""
+		}
+	}
+
+	c.SetSiteURLHeader(app.GetProtocol(r) + "://" + r.Host)
+
+	w.Header().Set(model.HEADER_REQUEST_ID, c.RequestId)
+	w.Header().Set(model.HEADER_VERSION_ID, fmt.Sprintf("%v.%v.%v.%v", model.CurrentVersion, model.BuildNumber, c.App.ClientConfigHash(), c.App.License() != nil))
+
+	if h.IsStatic {
+		// Instruct the browser not to display us in an iframe unless is the same origin for anti-clickjacking
+		w.Header().Set("X-Frame-Options", "SAMEORIGIN")
+		w.Header().Set("Content-Security-Policy", "frame-ancestors 'self'")
+	} else {
+		// All api response bodies will be JSON formatted by default
+		w.Header().Set("Content-Type", "application/json")
+
+		if r.Method == "GET" {
+			w.Header().Set("Expires", "0")
+		}
+	}
+
+	if len(token) != 0 {
+		session, err := c.App.GetSession(token)
+
+		if err != nil {
+			mlog.Info(fmt.Sprintf("Invalid session err=%v", err.Error()))
+			if err.StatusCode == http.StatusInternalServerError {
+				c.Err = err
+			} else if h.RequireSession {
+				c.RemoveSessionCookie(w, r)
+				c.Err = model.NewAppError("ServeHTTP", "api.context.session_expired.app_error", nil, "token="+token, http.StatusUnauthorized)
+			}
+		} else if !session.IsOAuth && tokenLocation == app.TokenLocationQueryString {
+			c.Err = model.NewAppError("ServeHTTP", "api.context.token_provided.app_error", nil, "token="+token, http.StatusUnauthorized)
+		} else {
+			c.Session = *session
+		}
+
+		// Rate limit by UserID
+		if c.App.Srv.RateLimiter != nil && c.App.Srv.RateLimiter.UserIdRateLimit(c.Session.UserId, w) {
+			return
+		}
+	}
+
+	c.Path = r.URL.Path
+
+	if c.Err == nil && h.RequireSession {
+		c.SessionRequired()
+	}
+
+	if c.Err == nil && h.RequireMfa {
+		c.MfaRequired()
+	}
+
+	if c.Err == nil {
+		h.HandleFunc(c, w, r)
+	}
+
+	// Handle errors that have occurred
+	if c.Err != nil {
+		c.Err.Translate(c.T)
+		c.Err.RequestId = c.RequestId
+
+		if c.Err.Id == "api.context.session_expired.app_error" {
+			c.LogInfo(c.Err)
+		} else {
+			c.LogError(c.Err)
+		}
+
+		c.Err.Where = r.URL.Path
+
+		// Block out detailed error when not in developer mode
+		if !*c.App.Config().ServiceSettings.EnableDeveloper {
+			c.Err.DetailedError = ""
+		}
+
+		w.WriteHeader(c.Err.StatusCode)
+		w.Write([]byte(c.Err.ToJson()))
+
+		if c.App.Metrics != nil {
+			c.App.Metrics.IncrementHttpError()
+		}
+	}
+
+	if c.App.Metrics != nil {
+		c.App.Metrics.IncrementHttpRequest()
+
+		if r.URL.Path != model.API_URL_SUFFIX+"/websocket" {
+			elapsed := float64(time.Since(now)) / float64(time.Second)
+			c.App.Metrics.ObserveHttpRequestDuration(elapsed)
+		}
+	}
+}