GPRS模块用TCP实现MQTT协议（基于SIM900A）

mqtt部分：

int strlen(char *str)
{
    int len = 0;
    while (*str != '\0') {
        len++;
        str++;
    }
    return len;
}  

// **********************************
// *                                *
// * 根据主机地址和端口号连接服务器 *
// *                                *
// **********************************  

void tcp_connect(char *host,int port)
{
   uart_send_str("AT\r\n");
   uart_send_str("AT+CPIN? \r\n");
   seelp(500);
   uart_send_str("AT+CREG? \r\n");
   seelp(500);
   uart_send_str("AT+CGATT? \r\n");
   seelp(500);
   uart_send_str("AT+CSTT=\"CMNET\" \r\n");
   seelp(500);
   uart_send_str("AT+CIICR \r\n");
   seelp(1500);
   uart_send_str("AT+CIFSR \r\n");
   seelp(1000);
   uart_send_str("AT+CIPSTART=\"TCP\"\,\"23.106.139.167\"\,\"1883\" \r\n"); //连接TCP Server  8081 1883
}  

// *************************
// *                       *
// *  构建MQTT连接包       *
// *                       *
// *************************  

int baseIndex;
int mqtt_connect_message(unsigned char *mqtt_message,char *client_id,char *username,char *password)
{
    char i = 0;
    char client_id_length = strlen(client_id);
    int username_length = strlen(username);
    int password_length = strlen(password);
    int packetLen = 12 + 2 + client_id_length + 2 + username_length + 2 + password_length;    

    mqtt_message[0] = 16;                      // MQTT Message Type CONNECT
    mqtt_message[1] = packetLen%256;
    baseIndex = 2;
    if( packetLen >127 ){//
        mqtt_message[2] = 1;//packetLen/127;
        baseIndex = 3;
    }    

    mqtt_message[baseIndex] = 0;                       // Protocol Name Length MSB
    mqtt_message[baseIndex+1] = 6;                       // Protocol Name Length LSB
    mqtt_message[baseIndex+2] = 77;                      // ASCII Code for M
    mqtt_message[baseIndex+3] = 81;                      // ASCII Code for Q
    mqtt_message[baseIndex+4] = 73;                      // ASCII Code for I
    mqtt_message[baseIndex+5] = 115;                     // ASCII Code for s
    mqtt_message[baseIndex+6] = 100;                     // ASCII Code for d
    mqtt_message[baseIndex+7] = 112;                     // ASCII Code for p
    mqtt_message[baseIndex+8] = 3;                      // MQTT Protocol version = 3
    mqtt_message[baseIndex+9] = 194;                   // conn flags
    mqtt_message[baseIndex+10] = 0;                      // Keep-alive Time Length MSB
    mqtt_message[baseIndex+11] = 60;                     // Keep-alive Time Length LSB    

    mqtt_message[baseIndex+12] = 0;                      // Client ID length MSB
    mqtt_message[baseIndex+13] = client_id_length;       // Client ID length LSB    

    baseIndex += 14;
    // Client ID
    for(i = 0; i < client_id_length; i++){
        mqtt_message[baseIndex + i] = client_id[i];
    }    

    baseIndex = baseIndex+client_id_length;    

    //username
    mqtt_message[baseIndex] = 0;                      //username length MSB
    mqtt_message[baseIndex+1] = username_length;       //username length LSB
    baseIndex = baseIndex+2;
    for(i = 0; i < username_length ; i++){
        mqtt_message[baseIndex + i] = username[i];
    }    

    baseIndex = baseIndex + username_length;    

    //password
    mqtt_message[baseIndex] = 0;                      //password length MSB
    mqtt_message[baseIndex+1] = password_length;       //password length LSB
    baseIndex = baseIndex + 2;
    for(i = 0; i < password_length ; i++){
        mqtt_message[baseIndex + i] = password[i];
    }    

    baseIndex += password_length;    

    return baseIndex;
}  

int mqtt_publish_message(unsigned char *mqtt_message, char * topic, char * message) {    

    //mqtt_message = 0;    

    unsigned char i = 0;
    unsigned char topic_length = strlen(topic);
    unsigned char message_length = strlen(message);    

    mqtt_message[0] = 48;                                  // MQTT Message Type CONNECT
    mqtt_message[1] = 2 + topic_length + message_length;   // Remaining length
    mqtt_message[2] = 0;                                   // MQTT Message Type CONNECT
    mqtt_message[3] = topic_length;                        // MQTT Message Type CONNECT    

    // Topic
    for(i = 0; i < topic_length; i++){
        mqtt_message[4 + i] = topic[i];
    }    

    // Message
    for(i = 0; i < message_length; i++){
        mqtt_message[4 + topic_length + i] = message[i];
    }    

    return 4 + topic_length + message_length;
}    

int subindex = 0;
int mqtt_subscribe_message(unsigned char *mqtt_message,unsigned char *topic)
{
    unsigned char topic_len = strlen(topic);
    mqtt_message[0] = 130;
    mqtt_message[1] = topic_len+5;
    mqtt_message[2] = 0;
    mqtt_message[3] = 1;
    mqtt_message[4] = 0;
    mqtt_message[5] = topic_len;    

    for (subindex=0; subindex<topic_len; subindex++) {
        mqtt_message[6+subindex] = topic[subindex];
    }
    mqtt_message[topic_len+6+1] = 0;
    return topic_len+7;
}

　　

mqtt部分：

[cpp] view plain copy

 

1. int strlen(char *str)
2. {
3. int len = 0;
4. while (*str != '\0') {
5. len++;
6. str++;
7. }
8. return len;
9. }
10. // **********************************
11. // *                                *
12. // * 根据主机地址和端口号连接服务器 *
13. // *                                *
14. // **********************************
15. void tcp_connect(char *host,int port)
16. {
17. uart_send_str("AT\r\n");
18. uart_send_str("AT+CPIN? \r\n");
19. seelp(500);
20. uart_send_str("AT+CREG? \r\n");
21. seelp(500);
22. uart_send_str("AT+CGATT? \r\n");
23. seelp(500);
24. uart_send_str("AT+CSTT=\"CMNET\" \r\n");
25. seelp(500);
26. uart_send_str("AT+CIICR \r\n");
27. seelp(1500);
28. uart_send_str("AT+CIFSR \r\n");
29. seelp(1000);
30. uart_send_str("AT+CIPSTART=\"TCP\"\,\"23.106.139.167\"\,\"1883\" \r\n"); //连接TCP Server  8081 1883
31. }
32. // *************************
33. // *                       *
34. // *  构建MQTT连接包       *
35. // *                       *
36. // *************************
37. int baseIndex;
38. int mqtt_connect_message(unsigned char *mqtt_message,char *client_id,char *username,char *password)
39. {
40. char i = 0;
41. char client_id_length = strlen(client_id);
42. int username_length = strlen(username);
43. int password_length = strlen(password);
44. int packetLen = 12 + 2 + client_id_length + 2 + username_length + 2 + password_length;
45. mqtt_message[0] = 16;                      // MQTT Message Type CONNECT
46. mqtt_message[1] = packetLen%256;
47. baseIndex = 2;
48. if( packetLen >127 ){//
49. mqtt_message[2] = 1;//packetLen/127;
50. baseIndex = 3;
51. }
52. mqtt_message[baseIndex] = 0;                       // Protocol Name Length MSB
53. mqtt_message[baseIndex+1] = 6;                       // Protocol Name Length LSB
54. mqtt_message[baseIndex+2] = 77;                      // ASCII Code for M
55. mqtt_message[baseIndex+3] = 81;                      // ASCII Code for Q
56. mqtt_message[baseIndex+4] = 73;                      // ASCII Code for I
57. mqtt_message[baseIndex+5] = 115;                     // ASCII Code for s
58. mqtt_message[baseIndex+6] = 100;                     // ASCII Code for d
59. mqtt_message[baseIndex+7] = 112;                     // ASCII Code for p
60. mqtt_message[baseIndex+8] = 3;                      // MQTT Protocol version = 3
61. mqtt_message[baseIndex+9] = 194;                   // conn flags
62. mqtt_message[baseIndex+10] = 0;                      // Keep-alive Time Length MSB
63. mqtt_message[baseIndex+11] = 60;                     // Keep-alive Time Length LSB
64. mqtt_message[baseIndex+12] = 0;                      // Client ID length MSB
65. mqtt_message[baseIndex+13] = client_id_length;       // Client ID length LSB
66. baseIndex += 14;
67. // Client ID
68. for(i = 0; i < client_id_length; i++){
69. mqtt_message[baseIndex + i] = client_id[i];
70. }
71. baseIndex = baseIndex+client_id_length;
72. //username
73. mqtt_message[baseIndex] = 0;                      //username length MSB
74. mqtt_message[baseIndex+1] = username_length;       //username length LSB
75. baseIndex = baseIndex+2;
76. for(i = 0; i < username_length ; i++){
77. mqtt_message[baseIndex + i] = username[i];
78. }
79. baseIndex = baseIndex + username_length;
80. //password
81. mqtt_message[baseIndex] = 0;                      //password length MSB
82. mqtt_message[baseIndex+1] = password_length;       //password length LSB
83. baseIndex = baseIndex + 2;
84. for(i = 0; i < password_length ; i++){
85. mqtt_message[baseIndex + i] = password[i];
86. }
87. baseIndex += password_length;
88. return baseIndex;
89. }
90. int mqtt_publish_message(unsigned char *mqtt_message, char * topic, char * message) {
91. //mqtt_message = 0;
92. unsigned char i = 0;
93. unsigned char topic_length = strlen(topic);
94. unsigned char message_length = strlen(message);
95. mqtt_message[0] = 48;                                  // MQTT Message Type CONNECT
96. mqtt_message[1] = 2 + topic_length + message_length;   // Remaining length
97. mqtt_message[2] = 0;                                   // MQTT Message Type CONNECT
98. mqtt_message[3] = topic_length;                        // MQTT Message Type CONNECT
99. // Topic
100. for(i = 0; i < topic_length; i++){
101. mqtt_message[4 + i] = topic[i];
102. }
103. // Message
104. for(i = 0; i < message_length; i++){
105. mqtt_message[4 + topic_length + i] = message[i];
106. }
107. return 4 + topic_length + message_length;
108. }
109. int subindex = 0;
110. int mqtt_subscribe_message(unsigned char *mqtt_message,unsigned char *topic)
111. {
112. unsigned char topic_len = strlen(topic);
113. mqtt_message[0] = 130;
114. mqtt_message[1] = topic_len+5;
115. mqtt_message[2] = 0;
116. mqtt_message[3] = 1;
117. mqtt_message[4] = 0;
118. mqtt_message[5] = topic_len;
119. for (subindex=0; subindex<topic_len; subindex++) {
120. mqtt_message[6+subindex] = topic[subindex];
121. }
122. mqtt_message[topic_len+6+1] = 0;
123. return topic_len+7;
124. }