1 /*
2 * ws protocol handler plugin for "lws-minimal"
3 *
4 * Written in 2010-2019 by Andy Green <andy@warmcat.com>
5 *
6 * This file is made available under the Creative Commons CC0 1.0
7 * Universal Public Domain Dedication.
8 *
9 * This version holds a single message at a time, which may be lost if a new
10 * message comes. See the minimal-ws-server-ring sample for the same thing
11 * but using an lws_ring ringbuffer to hold up to 8 messages at a time.
12 */
13
14 #if !defined (LWS_PLUGIN_STATIC)
15 #define LWS_DLL
16 #define LWS_INTERNAL
17 #include <libwebsockets.h>
18 #endif
19
20 #include <string.h>
21
22 /* one of these created for each message */
23
24 struct msg {
25 void *payload; /* is malloc'd */
26 size_t len;
27 };
28
29 /* one of these is created for each client connecting to us */
30
31 struct per_session_data__minimal {
32 struct per_session_data__minimal *pss_list;
33 struct lws *wsi;
34 int last; /* the last message number we sent */
35 };
36
37 /* one of these is created for each vhost our protocol is used with */
38
39 struct per_vhost_data__minimal {
40 struct lws_context *context;
41 struct lws_vhost *vhost;
42 const struct lws_protocols *protocol;
43
44 struct per_session_data__minimal *pss_list; /* linked-list of live pss*/
45
46 struct msg amsg; /* the one pending message... */
47 int current; /* the current message number we are caching */
48 };
49
50 /* destroys the message when everyone has had a copy of it */
51
52 static void
__minimal_destroy_message(void * _msg)53 __minimal_destroy_message(void *_msg)
54 {
55 struct msg *msg = _msg;
56
57 free(msg->payload);
58 msg->payload = NULL;
59 msg->len = 0;
60 }
61
62 static int
callback_minimal(struct lws * wsi,enum lws_callback_reasons reason,void * user,void * in,size_t len)63 callback_minimal(struct lws *wsi, enum lws_callback_reasons reason,
64 void *user, void *in, size_t len)
65 {
66 struct per_session_data__minimal *pss =
67 (struct per_session_data__minimal *)user;
68 struct per_vhost_data__minimal *vhd =
69 (struct per_vhost_data__minimal *)
70 lws_protocol_vh_priv_get(lws_get_vhost(wsi),
71 lws_get_protocol(wsi));
72 int m;
73
74 switch (reason) {
75 case LWS_CALLBACK_PROTOCOL_INIT:
76 vhd = lws_protocol_vh_priv_zalloc(lws_get_vhost(wsi),
77 lws_get_protocol(wsi),
78 sizeof(struct per_vhost_data__minimal));
79 vhd->context = lws_get_context(wsi);
80 vhd->protocol = lws_get_protocol(wsi);
81 vhd->vhost = lws_get_vhost(wsi);
82 break;
83
84 case LWS_CALLBACK_ESTABLISHED:
85 /* add ourselves to the list of live pss held in the vhd */
86 pss->pss_list = vhd->pss_list;
87 vhd->pss_list = pss;
88 pss->wsi = wsi;
89 pss->last = vhd->current;
90 break;
91
92 case LWS_CALLBACK_CLOSED:
93 /* remove our closing pss from the list of live pss */
94 lws_start_foreach_llp(struct per_session_data__minimal **,
95 ppss, vhd->pss_list) {
96 if (*ppss == pss) {
97 *ppss = pss->pss_list;
98 break;
99 }
100 } lws_end_foreach_llp(ppss, pss_list);
101 break;
102
103 case LWS_CALLBACK_SERVER_WRITEABLE:
104 if (!vhd->amsg.payload)
105 break;
106
107 if (pss->last == vhd->current)
108 break;
109
110 /* notice we allowed for LWS_PRE in the payload already */
111 m = lws_write(wsi, ((unsigned char *)vhd->amsg.payload) +
112 LWS_PRE, vhd->amsg.len, LWS_WRITE_TEXT);
113 if (m < (int)vhd->amsg.len) {
114 lwsl_err("ERROR %d writing to ws socket\n", m);
115 return -1;
116 }
117
118 pss->last = vhd->current;
119 break;
120
121 case LWS_CALLBACK_RECEIVE:
122 if (vhd->amsg.payload)
123 __minimal_destroy_message(&vhd->amsg);
124
125 vhd->amsg.len = len;
126 /* notice we over-allocate by LWS_PRE */
127 vhd->amsg.payload = malloc(LWS_PRE + len);
128 if (!vhd->amsg.payload) {
129 lwsl_user("OOM: dropping\n");
130 break;
131 }
132
133 memcpy((char *)vhd->amsg.payload + LWS_PRE, in, len);
134 vhd->current++;
135
136 /*
137 * let everybody know we want to write something on them
138 * as soon as they are ready
139 */
140 lws_start_foreach_llp(struct per_session_data__minimal **,
141 ppss, vhd->pss_list) {
142 lws_callback_on_writable((*ppss)->wsi);
143 } lws_end_foreach_llp(ppss, pss_list);
144 break;
145
146 default:
147 break;
148 }
149
150 return 0;
151 }
152
153 #define LWS_PLUGIN_PROTOCOL_MINIMAL \
154 { \
155 "lws-minimal", \
156 callback_minimal, \
157 sizeof(struct per_session_data__minimal), \
158 128, \
159 0, NULL, 0 \
160 }
161