BareRTC/pkg/polling_api.go

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2023-12-11 02:43:18 +00:00
package barertc
import (
"context"
"encoding/json"
"net/http"
"time"
"git.kirsle.net/apps/barertc/pkg/log"
"git.kirsle.net/apps/barertc/pkg/messages"
"git.kirsle.net/apps/barertc/pkg/util"
"github.com/google/uuid"
)
// Polling user timeout before disconnecting them.
const PollingUserTimeout = time.Minute
// JSON payload structure for polling API.
type PollMessage struct {
// Send the username after authenticated.
Username string `json:"username,omitempty"`
// SessionID for authentication.
SessionID string `json:"session_id,omitempty"`
// BareRTC protocol message.
Message messages.Message `json:"msg"`
}
type PollResponse struct {
// Session ID.
Username string `json:"username,omitempty"`
SessionID string `json:"session_id,omitempty"`
// Pending messages.
Messages []messages.Message `json:"messages"`
}
// Helper method to send an error as a PollResponse.
func PollResponseError(message string) PollResponse {
return PollResponse{
Messages: []messages.Message{
{
Action: messages.ActionError,
Username: "ChatServer",
Message: message,
},
},
}
}
// KickIdlePollUsers is a goroutine that will disconnect polling API users
// who haven't been seen in a while.
func (s *Server) KickIdlePollUsers() {
log.Debug("KickIdlePollUsers goroutine engaged")
for {
time.Sleep(10 * time.Second)
for _, sub := range s.IterSubscribers() {
if sub.usePolling && time.Since(sub.lastPollAt) > PollingUserTimeout {
// Send an exit message.
if sub.authenticated && sub.ChatStatus != "hidden" {
log.Error("KickIdlePollUsers: %s last seen %s ago", sub.Username, sub.lastPollAt)
sub.authenticated = false
s.Broadcast(messages.Message{
Action: messages.ActionPresence,
Username: sub.Username,
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Message: messages.PresenceTimedOut,
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})
s.SendWhoList()
}
s.DeleteSubscriber(sub)
}
}
}
}
// FlushPollResponse returns a response for the polling API that will flush
// all pending messages sent to the client.
func (sub *Subscriber) FlushPollResponse() PollResponse {
var msgs = []messages.Message{}
// Drain the messages from the outbox channel.
for len(sub.messages) > 0 {
message := <-sub.messages
var msg messages.Message
json.Unmarshal(message, &msg)
msgs = append(msgs, msg)
}
return PollResponse{
Username: sub.Username,
SessionID: sub.sessionID,
Messages: msgs,
}
}
// Functions for the Polling API as an alternative to WebSockets.
func (s *Server) PollingAPI() http.HandlerFunc {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
ip := util.IPAddress(r)
// JSON writer for the response.
w.Header().Set("Content-Type", "application/json")
enc := json.NewEncoder(w)
enc.SetIndent("", " ")
// Parse the request.
if r.Method != http.MethodPost {
w.WriteHeader(http.StatusBadRequest)
enc.Encode(PollResponseError("Only POST methods allowed"))
return
} else if r.Header.Get("Content-Type") != "application/json" {
w.WriteHeader(http.StatusBadRequest)
enc.Encode(PollResponseError("Only application/json content-types allowed"))
return
}
defer r.Body.Close()
// Parse the request payload.
var (
params PollMessage
dec = json.NewDecoder(r.Body)
)
if err := dec.Decode(&params); err != nil {
w.WriteHeader(http.StatusBadRequest)
enc.Encode(PollResponseError(err.Error()))
return
}
// Debug logging.
log.Debug("Polling connection from %s - %s", ip, r.Header.Get("User-Agent"))
// Are they resuming an authenticated session?
var sub *Subscriber
if params.Username != "" || params.SessionID != "" {
if params.Username == "" || params.SessionID == "" {
w.WriteHeader(http.StatusBadRequest)
enc.Encode(PollResponseError("Authentication error: SessionID and Username both required."))
return
}
log.Debug("Polling API: check if %s (%s) is authenticated", params.Username, params.SessionID)
// Look up the subscriber.
var (
authOK bool
err error
)
sub, err = s.GetSubscriber(params.Username)
if err == nil {
// Validate the SessionID.
if sub.sessionID == params.SessionID {
authOK = true
}
}
// Authentication error.
if !authOK {
s.DeleteSubscriber(sub)
w.WriteHeader(http.StatusBadRequest)
enc.Encode(PollResponse{
Messages: []messages.Message{
{
Action: messages.ActionError,
Username: "ChatServer",
Message: "Your authentication has expired, please log back into the chat again.",
},
{
Action: messages.ActionKick,
},
},
})
return
}
// Ping their last seen time.
sub.lastPollAt = time.Now()
}
// If they are authenticated, handle this message.
if sub != nil && sub.authenticated {
s.OnClientMessage(sub, params.Message)
// If they use JWT authentication, give them a ping back with an updated
// JWT once in a while. Equivalent to the WebSockets pinger channel.
if time.Since(sub.lastPollJWT) > PingInterval {
sub.lastPollJWT = time.Now()
if sub.JWTClaims != nil {
if jwt, err := sub.JWTClaims.ReSign(); err != nil {
log.Error("ReSign JWT token for %s#%d: %s", sub.Username, sub.ID, err)
} else {
sub.SendJSON(messages.Message{
Action: messages.ActionPing,
JWTToken: jwt,
})
}
}
}
enc.Encode(sub.FlushPollResponse())
return
}
// Not authenticated: the only acceptable message is login.
if params.Message.Action != messages.ActionLogin {
w.WriteHeader(http.StatusBadRequest)
enc.Encode(PollResponseError("Not logged in."))
return
}
// Prepare a Subscriber object for them. Do not add it to the server
// roster unless their login succeeds.
ctx, cancel := context.WithCancel(r.Context())
sub = s.NewPollingSubscriber(ctx, cancel)
// Tentatively add them to the server. If they don't pass authentication,
// remove their subscriber immediately. Note: they need added here so they
// will receive their own "has entered the room" and WhoList updates.
s.AddSubscriber(sub)
s.OnLogin(sub, params.Message)
// Are they authenticated?
if sub.authenticated {
// Generate a SessionID number.
sessionID := uuid.New().String()
sub.sessionID = sessionID
log.Debug("Polling API: new user authenticated in: %s (sid %s)", sub.Username, sub.sessionID)
} else {
s.DeleteSubscriber(sub)
}
enc.Encode(sub.FlushPollResponse())
})
}