1
2
3
4
5 package main
6
7 import (
8 "embed"
9 "flag"
10 "fmt"
11 "io/fs"
12 "log"
13 "net"
14 "net/http"
15 "net/url"
16 "os"
17 "strings"
18
19 "golang.org/x/tools/present"
20 )
21
22 var (
23 httpAddr = flag.String("http", "127.0.0.1:3999", "HTTP service address (e.g., '127.0.0.1:3999')")
24 originHost = flag.String("orighost", "", "host component of web origin URL (e.g., 'localhost')")
25 basePath = flag.String("base", "", "base path for slide template and static resources")
26 contentPath = flag.String("content", ".", "base path for presentation content")
27 usePlayground = flag.Bool("use_playground", false, "run code snippets using play.golang.org; if false, run them locally and deliver results by WebSocket transport")
28 )
29
30
31 var embedFS embed.FS
32
33 func main() {
34 flag.BoolVar(&present.PlayEnabled, "play", true, "enable playground (permit execution of arbitrary user code)")
35 flag.BoolVar(&present.NotesEnabled, "notes", false, "enable presenter notes (press 'N' from the browser to display them)")
36 flag.Parse()
37
38 if os.Getenv("GAE_ENV") == "standard" {
39 log.Print("Configuring for App Engine Standard")
40 port := os.Getenv("PORT")
41 if port == "" {
42 port = "8080"
43 }
44 *httpAddr = fmt.Sprintf("0.0.0.0:%s", port)
45 pwd, err := os.Getwd()
46 if err != nil {
47 log.Fatalf("Couldn't get pwd: %v\n", err)
48 }
49 *basePath = pwd
50 *usePlayground = true
51 *contentPath = "./content/"
52 }
53
54 var fsys fs.FS = embedFS
55 if *basePath != "" {
56 fsys = os.DirFS(*basePath)
57 }
58 err := initTemplates(fsys)
59 if err != nil {
60 log.Fatalf("Failed to parse templates: %v", err)
61 }
62
63 ln, err := net.Listen("tcp", *httpAddr)
64 if err != nil {
65 log.Fatal(err)
66 }
67 defer ln.Close()
68
69 _, port, err := net.SplitHostPort(ln.Addr().String())
70 if err != nil {
71 log.Fatal(err)
72 }
73
74 origin := &url.URL{Scheme: "http"}
75 if *originHost != "" {
76 if strings.HasPrefix(*originHost, "https://") {
77 *originHost = strings.TrimPrefix(*originHost, "https://")
78 origin.Scheme = "https"
79 }
80 *originHost = strings.TrimPrefix(*originHost, "http://")
81 origin.Host = net.JoinHostPort(*originHost, port)
82 } else if ln.Addr().(*net.TCPAddr).IP.IsUnspecified() {
83 name, _ := os.Hostname()
84 origin.Host = net.JoinHostPort(name, port)
85 } else {
86 reqHost, reqPort, err := net.SplitHostPort(*httpAddr)
87 if err != nil {
88 log.Fatal(err)
89 }
90 if reqPort == "0" {
91 origin.Host = net.JoinHostPort(reqHost, port)
92 } else {
93 origin.Host = *httpAddr
94 }
95 }
96
97 initPlayground(fsys, origin)
98 http.Handle("/static/", http.FileServer(http.FS(fsys)))
99
100 if !ln.Addr().(*net.TCPAddr).IP.IsLoopback() &&
101 present.PlayEnabled && !*usePlayground {
102 log.Print(localhostWarning)
103 }
104
105 log.Printf("Open your web browser and visit %s", origin.String())
106 if present.NotesEnabled {
107 log.Println("Notes are enabled, press 'N' from the browser to display them.")
108 }
109 log.Fatal(http.Serve(ln, nil))
110 }
111
112 func environ(vars ...string) []string {
113 env := os.Environ()
114 for _, r := range vars {
115 k := strings.SplitAfter(r, "=")[0]
116 var found bool
117 for i, v := range env {
118 if strings.HasPrefix(v, k) {
119 env[i] = r
120 found = true
121 }
122 }
123 if !found {
124 env = append(env, r)
125 }
126 }
127 return env
128 }
129
130 const basePathMessage = `
131 By default, gopresent locates the slide template files and associated
132 static content by looking for a %q package
133 in your Go workspaces (GOPATH).
134
135 You may use the -base flag to specify an alternate location.
136 `
137
138 const localhostWarning = `
139 WARNING! WARNING! WARNING!
140
141 The present server appears to be listening on an address that is not localhost
142 and is configured to run code snippets locally. Anyone with access to this address
143 and port will have access to this machine as the user running present.
144
145 To avoid this message, listen on localhost, run with -play=false, or run with
146 -play_socket=false.
147
148 If you don't understand this message, hit Control-C to terminate this process.
149
150 WARNING! WARNING! WARNING!
151 `
152
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