1 /*
2 * libwebsockets - small server side websockets and web server implementation
3 *
4 * Copyright (C) 2010 - 2020 Andy Green <andy@warmcat.com>
5 * Sakthi Kannan <saktr@amazon.com>
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a copy
8 * of this software and associated documentation files (the "Software"), to
9 * deal in the Software without restriction, including without limitation the
10 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
11 * sell copies of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
20 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
22 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
23 * IN THE SOFTWARE.
24 */
25
26 #include <private-lib-core.h>
27
28 #define MQTT_CONNECT_MSG_BASE_LEN (12)
29
30 struct lws *
lws_mqtt_client_send_connect(struct lws * wsi)31 lws_mqtt_client_send_connect(struct lws *wsi)
32 {
33 /* static int */
34 /* lws_mqttc_abs_writeable(lws_abs_protocol_inst_t *api, size_t budget) */
35 const lws_mqttc_t *c = &wsi->mqtt->client;
36 uint8_t b[256 + LWS_PRE], *start = b + LWS_PRE, *p = start,
37 len = MQTT_CONNECT_MSG_BASE_LEN;
38
39 switch (lwsi_state(wsi)) {
40 case LRS_MQTTC_IDLE:
41 /*
42 * Transport connected - this is our chance to do the
43 * protocol connect action.
44 */
45
46 /* 1. Fixed Headers */
47 if (lws_mqtt_fill_fixed_header(p++, LMQCP_CTOS_CONNECT, 0, 0, 0)) {
48 lwsl_err("%s: Failled to fill fixed header\n", __func__);
49 return NULL;
50 }
51
52 /*
53 * 2. Remaining length - Add the lengths of client ID,
54 * username and password and their length fields if
55 * the respective flags are set.
56 */
57 len += c->id->len;
58 if (c->conn_flags & LMQCFT_USERNAME && c->username) {
59 len += c->username->len + 2;
60 if (c->conn_flags & LMQCFT_PASSWORD)
61 len += (c->password ? c->password->len : 0) + 2;
62 }
63 if (c->conn_flags & LMQCFT_WILL_FLAG && c->will.topic) {
64 len += c->will.topic->len + 2;
65 len += (c->will.message ? c->will.message->len : 0) + 2;
66 }
67 p += lws_mqtt_vbi_encode(len, p);
68
69 /*
70 * 3. Variable Header - Protocol name & level, Connect
71 * flags and keep alive time (in secs).
72 */
73 lws_ser_wu16be(p, 4); /* Length of protocol name */
74 p += 2;
75 *p++ = 'M';
76 *p++ = 'Q';
77 *p++ = 'T';
78 *p++ = 'T';
79 *p++ = MQTT_VER_3_1_1;
80 *p++ = c->conn_flags;
81 lws_ser_wu16be(p, c->keep_alive_secs);
82 p += 2;
83
84 /*
85 * 4. Payload - Client ID, Will topic & message,
86 * Username & password.
87 */
88 if (lws_mqtt_str_is_not_empty(c->id)) {
89 lws_ser_wu16be(p, c->id->len);
90 p += 2;
91 memcpy(p, c->id->buf, c->id->len);
92 p += c->id->len;
93 } else {
94 /*
95 * If the Client supplies a zero-byte
96 * ClientId, the Client MUST also set
97 * CleanSession to 1 [MQTT-3.1.3-7].
98 */
99 if (!(c->conn_flags & LMQCFT_CLEAN_START)) {
100 lwsl_err("%s: Empty client ID needs a clean start\n",
101 __func__);
102 return NULL;
103 }
104 *p++ = 0;
105 }
106
107 if ((c->conn_flags & ~LMQCFT_CLEAN_START) == 0) {
108 *p++ = 0; /* no properties */
109 break;
110 }
111 if (c->conn_flags & LMQCFT_WILL_FLAG) {
112 if (lws_mqtt_str_is_not_empty(c->will.topic)) {
113 lws_ser_wu16be(p, c->will.topic->len);
114 p += 2;
115 memcpy(p, c->will.topic->buf, c->will.topic->len);
116 p += c->will.topic->len;
117 if (lws_mqtt_str_is_not_empty(c->will.message)) {
118 lws_ser_wu16be(p, c->will.topic->len);
119 p += 2;
120 memcpy(p, c->will.message->buf,
121 c->will.message->len);
122 p += c->will.message->len;
123 } else {
124 lws_ser_wu16be(p, 0);
125 p += 2;
126 }
127 } else {
128 lwsl_err("%s: Missing Will Topic\n", __func__);
129 return NULL;
130 }
131 }
132 if (c->conn_flags & LMQCFT_USERNAME) {
133 /*
134 * Detailed sanity check on the username and
135 * password strings.
136 */
137 if (lws_mqtt_str_is_not_empty(c->username)) {
138 lws_ser_wu16be(p, c->username->len);
139 p += 2;
140 memcpy(p, c->username->buf, c->username->len);
141 p += c->username->len;
142 } else {
143 lwsl_err("%s: Empty / missing Username!\n",
144 __func__);
145 return NULL;
146 }
147 if (c->conn_flags & LMQCFT_PASSWORD) {
148 if (lws_mqtt_str_is_not_empty(c->password)) {
149 lws_ser_wu16be(p, c->password->len);
150 p += 2;
151 memcpy(p, c->password->buf,
152 c->password->len);
153 p += c->password->len;
154 } else {
155 lws_ser_wu16be(p, 0);
156 p += 2;
157 }
158 }
159 } else if (c->conn_flags & LMQCFT_PASSWORD) {
160 lwsl_err("%s: Unsupported - Password without username\n",
161 __func__);
162 return NULL;
163 }
164 break;
165 default:
166 lwsl_err("%s: unexpected state %d\n", __func__, lwsi_state(wsi));
167
168 return NULL;
169 }
170
171 /*
172 * Perform the actual write
173 */
174 if (lws_write(wsi, (unsigned char *)&b[LWS_PRE], lws_ptr_diff(p, start),
175 LWS_WRITE_BINARY) != lws_ptr_diff(p, start)) {
176 lwsl_notice("%s: write failed\n", __func__);
177
178 return NULL;
179 }
180
181 return wsi;
182 }
183