diff options
Diffstat (limited to 'wsp.go')
| -rw-r--r-- | wsp.go | 143 |
1 files changed, 0 insertions, 143 deletions
@@ -1,143 +0,0 @@ -/* - * WebSocket-based protocol auxiliary functions - * - * Copyright (C) 2024 Runxi Yu <https://runxiyu.org> - * SPDX-License-Identifier: AGPL-3.0-or-later - * - * This program is free software: you can redistribute it and/or modify - * it under the terms of the GNU Affero General Public License as published by - * the Free Software Foundation, either version 3 of the License, or - * (at your option) any later version. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU Affero General Public License for more details. - * - * You should have received a copy of the GNU Affero General Public License - * along with this program. If not, see <https://www.gnu.org/licenses/>. - */ - -package main - -import ( - "context" - "fmt" - "sync/atomic" - - "github.com/coder/websocket" -) - -/* - * The message format is a WebSocket message separated with spaces. - * The contents of each field could contain anything other than spaces, - * The first character of each argument cannot be a colon. As an exception, the - * last argument may contain spaces and the first character thereof may be a - * colon, if the argument is prefixed with a colon. The colon used for the - * prefix is not considered part of the content of the message. For example, in - * - * SQUISH POP :cat purr!! - * - * the first field is "SQUISH", the second field is "POP", and the third - * field is "cat purr!!". - * - * It is essentially an RFC 1459 IRC message without trailing CR-LF and - * without prefixes. See section 2.3.1 of RFC 1459 for an approximate - * BNF representation. - * - * The reason this was chosen instead of using protobuf etc. is that it - * is simple to parse without external libraries, and it also happens to - * be a format I'm very familiar with, having extensively worked with the - * IRC protocol. - */ - -/* - * Split an IRC-style message of type []byte into type []string where each - * element is a complete argument. Generally, arguments are separated by - * spaces, and an argument that begins with a ':' causes the rest of the - * line to be treated as a single argument. - */ -func splitMsg(b *[]byte) []string { - mar := make([]string, 0, config.Perf.MessageArgumentsCap) - elem := make([]byte, 0, config.Perf.MessageBytesCap) - for i, c := range *b { - switch c { - case ' ': - if (*b)[i+1] == ':' { - mar = append(mar, string(elem)) - mar = append(mar, string((*b)[i+2:])) - goto endl - } - mar = append(mar, string(elem)) - elem = make([]byte, 0, config.Perf.MessageBytesCap) - default: - elem = append(elem, c) - } - } - mar = append(mar, string(elem)) -endl: - return mar -} - -func baseReportError( - ctx context.Context, - conn *websocket.Conn, - e string, -) error { - err := writeText(ctx, conn, "E :"+e) - if err != nil { - return fmt.Errorf("error reporting protocol violation: %w", err) - } - err = conn.Close(websocket.StatusProtocolError, e) - if err != nil { - return fmt.Errorf("error closing websocket: %w", err) - } - return nil -} - -type reportErrorT func(e string) error - -func makeReportError(ctx context.Context, conn *websocket.Conn) reportErrorT { - return func(e string) error { - return baseReportError(ctx, conn, e) - } -} - -func propagateSelectedUpdate(course *courseT) { - course.Usems.Range(func(key, value interface{}) bool { - _ = key - usem, ok := value.(*usemT) - if !ok { - panic("Usems contains non-\"*usemT\" value") - } - usem.set() - return true - }) -} - -func sendSelectedUpdate( - ctx context.Context, - conn *websocket.Conn, - courseID int, -) error { - _course, ok := courses.Load(courseID) - if !ok { - return fmt.Errorf("%w: %d", errNoSuchCourse, courseID) - } - course, ok := _course.(*courseT) - if !ok { - panic("courses map has non-\"*courseT\" items") - } - if course == nil { - return fmt.Errorf("%w: %d", errNoSuchCourse, courseID) - } - selected := atomic.LoadUint32(&course.Selected) - err := writeText(ctx, conn, fmt.Sprintf("M %d %d", courseID, selected)) - if err != nil { - return fmt.Errorf( - "error sending to websocket for course selected update: %w", - err, - ) - } - return nil -} |