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cmd_serve.go
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cmd_serve.go
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//
// This is a golang port of the purple-alert server.
//
// Incoming submissions are received over HTTP POSTS to /events, and
// alerts are processed as expected.
//
// There is also a web-view, for processing events.
//
// Steve
// --
//
package main
import (
"context"
"encoding/json"
"flag"
"fmt"
"io/ioutil"
"net"
"net/http"
"os"
"strings"
"time"
"github.com/google/subcommands"
"github.com/gorilla/handlers"
"github.com/gorilla/mux"
"github.com/gorilla/securecookie"
_ "github.com/skx/golang-metrics"
"github.com/skx/purppura/alert"
"github.com/skx/purppura/alerts"
)
// key is the type for a context-key
//
// We use context to store the remote host (URI), username, & password
// in our session-cookie.
type key int
const (
// keyUser stores the username.
keyUser key = iota
)
//
// The secure-cookie object we use.
//
var cookieHandler *securecookie.SecureCookie
//
// The persistence object for getting/setting alerts.
//
var storage *alerts.Alerts
// LoadCookie loads the persistent cookies from disc, if they exist.
func LoadCookie() {
//
// Read the hash
//
hash, err := ioutil.ReadFile(".cookie.hsh")
if err == nil {
//
// If there was no error read the block
//
var block []byte
block, err = ioutil.ReadFile(".cookie.blk")
if err == nil {
//
// And create the cookie-helper.
//
cookieHandler = securecookie.New(hash, block)
return
}
}
//
// So we either failed to find, or failed to read, the existing
// values. (Perhaps this is the first run.)
//
// Generate random values.
//
h := securecookie.GenerateRandomKey(64)
b := securecookie.GenerateRandomKey(32)
//
// Now write them out.
//
// If writing fails then we'll use the values, and this means
// when the server restarts authentication will need to to be
// repeated by the users.
//
// (i.e. They'll be logged out.)
//
err = ioutil.WriteFile(".cookie.hsh", h, 0644)
if err != nil {
fmt.Printf("WARNING: failed to write .cookie.hsh for our secure cookie")
cookieHandler = securecookie.New(h, b)
return
}
err = ioutil.WriteFile(".cookie.blk", b, 0644)
if err != nil {
fmt.Printf("WARNING: failed to write .cookie.blk for our secure cookie")
cookieHandler = securecookie.New(h, b)
return
}
//
// Create the cookie, if we got here we've saved the data
// for the next restart.
//
cookieHandler = securecookie.New(h, b)
}
// LoadEvents sets up a new (MySQL) database-connection.
func LoadEvents() error {
var err error
storage, err = alerts.New()
if err != nil {
return err
}
return nil
}
// AddContext updates our HTTP-handlers to be username-aware.
func AddContext(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
//
// If we have a session-cookie
//
if cookie, err := r.Cookie("cookie"); err == nil {
// Make a map
cookieValue := make(map[string]string)
// Decode it.
if err = cookieHandler.Decode("cookie", cookie.Value, &cookieValue); err == nil {
//
// Add the context to the handler, with the
// username.
//
userName := cookieValue["name"]
ctx := context.WithValue(r.Context(), keyUser, userName)
//
// And fire it up.
//
next.ServeHTTP(w, r.WithContext(ctx))
return
}
}
//
// We either failed to decode the cookie, or the cookie
// was missing.
//
// So we fall-back to assuming we're there is no user logged
// in, and supply no context.
//
next.ServeHTTP(w, r)
})
}
// RemoteIP handles retrieving the remote IP which made a particular
// HTTP-request, handling reverse-proxies as well as direct connections.
func RemoteIP(request *http.Request) string {
//
// Get the X-Forwarded-For header, if present.
//
xForwardedFor := request.Header.Get("X-Forwarded-For")
//
// No forwarded IP? Then use the remote address directly.
//
if xForwardedFor == "" {
ip, _, _ := net.SplitHostPort(request.RemoteAddr)
return ip
}
entries := strings.Split(xForwardedFor, ",")
address := strings.TrimSpace(entries[0])
return (address)
}
// alertSubmissionHandler receives alerts from remote sources and
// stores them in our database.
func alertSubmissionHandler(res http.ResponseWriter, request *http.Request) {
//
// We'll read JSON from STDIN.
//
// We do this manually because we want to see if we're
// getting a single event:
//
// {id:"blah",...}
//
// Or an array of events:
//
// [{id:"blah", ..},{id:"more-blah"..}
//
content, err := ioutil.ReadAll(request.Body)
if err != nil {
http.Error(res, err.Error(), 400)
return
}
//
// The incoming JSON might contain a single entry, or
// an array of entries.
//
var single alert.Alert
var multi []alert.Alert
//
// Decode - into the array, or single entry, as appropriate.
//
if strings.HasPrefix(string(content), "[") {
err = json.Unmarshal(content, &multi)
} else {
err = json.Unmarshal(content, &single)
}
if err != nil {
http.Error(res, err.Error(), 400)
return
}
//
// Get the source of the submission.
//
ip := RemoteIP(request)
//
// Did we get multiple entries?
//
if len(multi) > 0 {
//
// For each one - add it
//
for _, ent := range multi {
//
// Ensure the alert has an IP.
//
if ent.Source == "" {
ent.Source = ip
}
//
// Ensure we have all the fields we expect
//
if ent.Subject == "" {
http.Error(res, "Missing 'subject' field", 500)
return
}
if ent.ID == "" {
http.Error(res, "Missing 'ID' field", 500)
return
}
if ent.Raise == "" {
http.Error(res, "Missing 'raise' field", 500)
return
}
if ent.Detail == "" {
http.Error(res, "Missing 'detail' field", 500)
return
}
//
// Remove any IPv6-prefix, if present, on the source IP.
//
ent.Source = strings.TrimPrefix(ent.Source, "::ffff:")
//
// Add the event.
//
err = storage.AddEvent(ent)
if err != nil {
fmt.Printf("ERROR - addMulti%s\n", err.Error())
http.Error(res, err.Error(), 400)
return
}
}
} else {
//
// Ensure the alert has a source specified.
//
if single.Source == "" {
single.Source = ip
}
//
// Ensure we have all the fields we expect
//
if single.Subject == "" {
http.Error(res, "Missing 'subject' field", 500)
return
}
if single.ID == "" {
http.Error(res, "Missing 'ID' field", 500)
return
}
if single.Raise == "" {
http.Error(res, "Missing 'raise' field", 500)
return
}
if single.Detail == "" {
http.Error(res, "Missing 'detail' field", 500)
return
}
//
// Remove any IPv6-prefix, if present, on the source IP.
//
single.Source = strings.TrimPrefix(single.Source, "::ffff:")
//
// Add it.
//
err = storage.AddEvent(single)
if err != nil {
fmt.Printf("ERROR - AddSingle:%s\n", err.Error())
http.Error(res, err.Error(), 400)
return
}
}
//
// Send a simple reply to the caller.
//
fmt.Fprintf(res, "OK")
}
//
// Acknowledge an event.
//
func ackEvent(res http.ResponseWriter, req *http.Request) {
//
// Ensure the user is logged-in.
//
username := req.Context().Value(keyUser)
if username == nil {
http.Redirect(res, req, "/login", http.StatusFound)
return
}
//
// Get the ID we're going to acknowledge
//
vars := mux.Vars(req)
id := vars["id"]
storage.AckEvent(id)
http.Redirect(res, req, "/", http.StatusFound)
}
//
// Clear an event.
//
func clearEvent(res http.ResponseWriter, req *http.Request) {
//
// Ensure the user is logged-in.
//
username := req.Context().Value(keyUser)
if username == nil {
http.Redirect(res, req, "/login", http.StatusFound)
return
}
//
// Get the ID we're going to clear.
//
vars := mux.Vars(req)
id := vars["id"]
storage.ClearEvent(id)
http.Redirect(res, req, "/", http.StatusFound)
}
//
// Raise an event.
//
func raiseEvent(res http.ResponseWriter, req *http.Request) {
//
// Ensure the user is logged-in.
//
username := req.Context().Value(keyUser)
if username == nil {
http.Redirect(res, req, "/login", http.StatusFound)
return
}
//
// Get the ID we're going to raise.
//
vars := mux.Vars(req)
id := vars["id"]
storage.RaiseEvent(id)
http.Redirect(res, req, "/", http.StatusFound)
}
//
// Serve a static-resource
//
func serveResource(response http.ResponseWriter, request *http.Request, resource string, mime string) {
tmpl, err := getResource(resource)
if err != nil {
fmt.Fprint(response, err.Error())
return
}
response.Header().Set("Content-Type", mime)
fmt.Fprint(response, string(tmpl))
}
//
// Serve the login-form
//
func loginForm(response http.ResponseWriter, request *http.Request) {
serveResource(response, request, "data/login.html", "text/html; charset=utf-8")
}
//
// Process a login-event.
//
func loginHandler(response http.ResponseWriter, request *http.Request) {
//
// Get the username/password from the incoming form
// submission.
//
name := request.FormValue("name")
pass := request.FormValue("password")
//
// Open our list of users/passwords
//
valid, err := storage.ValidateLogin(name, pass)
if err != nil {
http.Error(response, err.Error(), 400)
return
}
//
// If this succeeded then let the login succeed.
//
if valid {
value := map[string]string{
"name": name,
}
if encoded, err := cookieHandler.Encode("cookie", value); err == nil {
cookie := &http.Cookie{
Name: "cookie",
Value: encoded,
Path: "/",
}
http.SetCookie(response, cookie)
}
http.Redirect(response, request, "/", http.StatusFound)
return
}
//
// Failure to login, redirect to try again.
//
http.Redirect(response, request, "/login#failed", http.StatusFound)
}
//
// logout handler
//
func logoutHandler(response http.ResponseWriter, request *http.Request) {
cookie := &http.Cookie{
Name: "cookie",
Value: "",
Path: "/",
MaxAge: -1,
}
http.SetCookie(response, cookie)
http.Redirect(response, request, "/", http.StatusFound)
}
//
// Get all events as a JSON array.
//
// This is used by /purppura.js to dynamically update the display.
//
func eventsHandler(response http.ResponseWriter, request *http.Request) {
//
// Ensure the user is logged-in.
//
username := request.Context().Value(keyUser)
if username == nil {
http.Redirect(response, request, "/login", http.StatusFound)
return
}
//
// Get all the alerts, and their states.
//
results, err := storage.Alerts()
if err != nil {
http.Error(response, err.Error(), http.StatusInternalServerError)
return
}
//
// Ensure that we send a suitable content-type.
//
response.Header().Set("Content-Type", "application/json")
//
// Output the alerts.
//
if len(results) > 0 {
out, _ := json.Marshal(results)
fmt.Fprintf(response, "%s", out)
} else {
fmt.Fprintf(response, "[]")
}
}
//
// index page
//
func indexPageHandler(response http.ResponseWriter, request *http.Request) {
//
// Ensure the user is logged-in.
//
username := request.Context().Value(keyUser)
if username == nil {
http.Redirect(response, request, "/login", http.StatusFound)
return
}
serveResource(response, request, "data/index.html", "text/html; charset=utf-8")
}
//
// serve our JS
//
func jsPage(response http.ResponseWriter, request *http.Request) {
serveResource(response, request, "data/purppura.js", "application/javascript")
}
//
// The options set by our command-line flags.
//
type serveCmd struct {
bindHost string
bindPort int
notifyBinary string
}
//
// Glue
//
func (*serveCmd) Name() string { return "serve" }
func (*serveCmd) Synopsis() string { return "Launch the HTTP server." }
func (*serveCmd) Usage() string {
return `serve [options]:
Launch the HTTP server for receiving and viewing alerts
`
}
//
// Flag setup
//
func (p *serveCmd) SetFlags(f *flag.FlagSet) {
f.IntVar(&p.bindPort, "port", 8080, "The port to bind upon.")
f.StringVar(&p.bindHost, "host", "127.0.0.1", "The IP to listen upon.")
f.StringVar(&p.notifyBinary, "notify-binary", "purppura-notify", "The binary to execute to issue notifications")
}
//
// Entry-point.
//
func (p *serveCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}) subcommands.ExitStatus {
//
// Start the server
//
serve(*p)
//
// All done.
//
return subcommands.ExitSuccess
}
//
// Entry-point.
//
func serve(settings serveCmd) {
//
// Configure our secure cookies
//
LoadCookie()
//
// Ensure we have a database for our HTTP-handler
//
err := LoadEvents()
if err != nil {
fmt.Printf("Error with DB setup: %s\n", err.Error())
os.Exit(1)
}
//
// Create a scheduler to process our events frequently enough
// to be responsive.
//
go ProcessAlertsScheduler(settings.notifyBinary)
//
// Configure our routes.
//
var router = mux.NewRouter()
router.HandleFunc("/", indexPageHandler)
router.HandleFunc("/purppura.js", jsPage).Methods("GET")
router.HandleFunc("/login", loginForm).Methods("GET")
router.HandleFunc("/login/", loginForm).Methods("GET")
router.HandleFunc("/login", loginHandler).Methods("POST")
router.HandleFunc("/login/", loginHandler).Methods("POST")
router.HandleFunc("/logout", logoutHandler).Methods("GET")
router.HandleFunc("/logout/", logoutHandler).Methods("GET")
router.HandleFunc("/logout", logoutHandler).Methods("POST")
router.HandleFunc("/logout/", logoutHandler).Methods("POST")
router.HandleFunc("/events", eventsHandler).Methods("GET")
router.HandleFunc("/events/", eventsHandler).Methods("GET")
router.HandleFunc("/events", alertSubmissionHandler).Methods("POST")
router.HandleFunc("/events/", alertSubmissionHandler).Methods("POST")
router.HandleFunc("/acknowledge/{id}", ackEvent).Methods("GET")
router.HandleFunc("/clear/{id}", clearEvent).Methods("GET")
router.HandleFunc("/raise/{id}", raiseEvent).Methods("GET")
http.Handle("/", router)
//
// Show what we're going to bind upon.
//
bind := fmt.Sprintf("%s:%d", settings.bindHost, settings.bindPort)
fmt.Printf("Listening on http://%s/\n", bind)
//
// Wire up logging.
//
loggedRouter := handlers.LoggingHandler(os.Stdout, router)
//
// Wire up context (i.e. cookie-based session stuff.)
//
contextRouter := AddContext(loggedRouter)
//
// We want to make sure we handle timeouts effectively
//
srv := &http.Server{
Addr: bind,
Handler: contextRouter,
ReadTimeout: 25 * time.Second,
IdleTimeout: 25 * time.Second,
WriteTimeout: 25 * time.Second,
}
//
// Launch the server.
//
err = srv.ListenAndServe()
if err != nil {
fmt.Printf("\nError starting HTTP server: %s\n", err.Error())
}
}