图解连接阿里云(二)使用Paho-MQTT(支持FreeRTOS版本、Linux版本)连接1MQTT测试服务器 2阿里云物联网平台
前沿提要：
MQTT是什么不知道？
看这一篇：https://www.cnblogs.com/happybirthdaytoyou/p/10362336.html
阿里云官网玩不转？
看这一篇： https://www.cnblogs.com/happybirthdaytoyou/p/14065294.html
不会用代码连接阿里云？
看这一篇：https://www.cnblogs.com/happybirthdaytoyou/p/14074606.html
Paho-MQTT
前往下载 https://gitee.com/mirrors/paho.mqtt.embedded-c?_from=gitee_search
我当前使用版本：
链接：https://pan.baidu.com/s/1pkUyD2mcQlQQur2GZHryCw
提取码：kcpo
0. 简介
Paho嵌入式C工程提供了以下三个子项目：
- MQTTPacket： 这里提供MQTT数据包的序列化与反序列化，以及部分辅助函数。
- 它们是高级库的基础，但也可以单独使用。主要取决于您对网络的读写，大概意思就是如果你对MQTT源码很熟悉，你可以直接使用MQTTPacket的接口。
- MQTTClient： 封装MQTTPacket生成的高级别C++客户端程序。
- MQTTClient-C：封装MQTTPacket生成的高级别C客户端程序。
-
MQTTClient-C中包含：
├── CMakeLists.txt ├── samples │ ├── CMakeLists.txt │ ├── FreeRTOS │ └── linux ├── src │ ├── CMakeLists.txt │ ├── FreeRTOS │ ├── MQTTClient.c │ ├── MQTTClient.h │ ├── cc3200 │ └── linux └── test ├── CMakeLists.txt └── test1.c- samples目录提供FreeRTOS和linux两个例程，分别支持FreeRTOS和Linux系统。
- src目录提供MQTTClient的代码实现能力，以及用于移植到FreeRTOS、cc3200和Linux的网络驱动。
代码编译方法
mkdir mybuild
cd mybuild
cmake ..
make
添加两个源文件，然后修改CMakeLists.txt
修改后的CMakeLists.txt：
add_executable(
aiot_c_demo
aiot_c_demo.c
aiot_mqtt_sign.c
)
target_link_libraries(aiot_c_demo paho-embed-mqtt3cc paho-embed-mqtt3c)
target_include_directories(aiot_c_demo PRIVATE "../../src" "../../src/linux")
target_compile_definitions(aiot_c_demo PRIVATE MQTTCLIENT_PLATFORM_HEADER=MQTTLinux.h)
1. 连接MQTT测试服务器
使用的测试服务器：
aiot_c_demo.c 这是你主要编写的代码，你可以参考我下面的
/**
这个例子是发布消息到MQTT测试服务器 test.mosquitto.org 上去。
我windows上的MQTT客户端软件订阅了该主题，所以可以收到这里发送的消息。
**/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "MQTTClient.h"
#include <unistd.h>
#define ADDRESS "test.mosquitto.org" // MQTT Test Server For Free
#define PORT 1883
#define CLIENTID // 客户端ID
const char *subTopic = "/publish/TEST/111";
const char *pubTopic = "/publish/TEST/000";
char clientId[150] = {0};
char username[65] = {0};
char password[65] = {0};
unsigned char sendbuf[1000];
unsigned char readbuf[1000];
void messageArrived(MessageData* md)
{
MQTTMessage* message = md->message;
printf("\nIOT Cloud Message Arrived! \n");
printf("%.*s\n", md->topicName->lenstring.len, md->topicName->lenstring.data);
printf("%.*s\n\n", (int)message->payloadlen, (char*)message->payload);
}
int main(int argc, char* argv[])
{
Network net;
MQTTClient client;
char *host = ADDRESS;
short port = PORT;
/* network init and establish network */
NetworkInit(&net);
int rc = NetworkConnect(&net, host, port);
if(!rc){
printf("\nNetworkConnect Success \n");
}
else{
printf("\nNetworkConnect ERR \n\n");
}
/**************MQTT Client Init***************/
MQTTClientInit(&client, &net, 1000, sendbuf, sizeof(sendbuf), readbuf, sizeof(readbuf));
/* set the default message handler */
client.defaultMessageHandler = messageArrived;
/**************MQTTConnect***************/
/* set mqtt connect parameter */
MQTTPacket_connectData data = MQTTPacket_connectData_initializer;
data.willFlag = 0;
//data.MQTTVersion = 3; 版本号不要指定，要不然连接服务器(执行MQTTConnect时)会返回失败
data.clientID.cstring = clientId; //clientId;
data.username.cstring = username;
data.password.cstring = password;
data.keepAliveInterval = 60;
data.cleansession = 1;
printf("......Try to Connect to %s %d, ......\n", host, port);
rc = MQTTConnect(&client, &data);
if(!rc)
printf("MQTTConnect %d, Connect MQTT IoT Cloud Success!\n", rc);
else
printf("MQTTConnect %d, Connect ERR!\n", rc);
/**************MQTTSubscribe***************/
rc = MQTTSubscribe(&client, subTopic, 1, messageArrived);
if(!rc)
printf("MQTTSubscribe %d, MQTTSubscribe MQTT IoT Cloud Success!\n", rc);
else
printf("MQTTSubscribe %d, MQTTSubscribe ERR!\n", rc);
/**************MQTTPublish***************/
#define mqttdata "hello mqtt"
MQTTMessage msg = {
QOS1,
1, // retained .
0,
0, // id
mqttdata,
strlen(mqttdata),
};
msg.id++;
rc = MQTTPublish(&client, pubTopic, &msg);
if(!rc)
printf("MQTTPublish %d, id = %d MQTTPublish MQTT IoT Cloud Success! \n", rc, msg.id);
else
printf("MQTTPublish %d, MQTTPublish ERR!\n", rc);
while(1){
MQTTYield(&client, 1000); // 在需要接收数据时, 都需要主动调用该函数
printf("---1s--- \n ");
}
return rc;
}
aiot_mqtt_sign.c 暂时为空文件即可， 连接阿里云时才会使用到。
先填好通信猫软件上的参数
注意，这里填写的发布和订阅的主题是和aiot_c_demo.c内的发布订阅的主题对应的。 MQTT，依靠主题来建立不同客户端的关联。
PS：通信猫软件下载地址
ubuntu内编译程序，准备运行
运行结果:
2. 连接阿里云物联网平台
这里会使用到aiot_mqtt_sign.c
aiot_mqtt_sign.c加上内容吧， 赋值黏贴拿去使用即可，这里面的代码可以不用关心，主要是提供一个计算密码的功能函数：
/* * Copyright (C) 2015-2019 Alibaba Group Holding Limited */ #include <stdlib.h> #include <stdio.h> #include <string.h> #include <stdint.h> #define PRODUCTKEY_MAXLEN (20) #define DEVICENAME_MAXLEN (32) #define DEVICESECRET_MAXLEN (64) #define SIGN_SOURCE_MAXLEN (200) #define CLIENTID_MAXLEN (150) #define USERNAME_MAXLEN (64) #define PASSWORD_MAXLEN (65) #define TIMESTAMP_VALUE "2524608000000" #define MQTT_CLINETID_KV "|timestamp=2524608000000,_v=paho-c-1.0.0,securemode=3,signmethod=hmacsha256,lan=C|" static void utils_hmac_sha256(const uint8_t *msg, uint32_t msg_len, const uint8_t *key, uint32_t key_len, uint8_t output[32]); static void _hex2str(uint8_t *input, uint16_t input_len, char *output) { char *zEncode = "0123456789ABCDEF"; int i = 0, j = 0; for (i = 0; i < input_len; i++) { output[j++] = zEncode[(input[i] >> 4) & 0xf]; output[j++] = zEncode[(input[i]) & 0xf]; } } int aiotMqttSign(const char *productKey, const char *deviceName, const char *deviceSecret, char clientId[150], char username[64], char password[65]) { char deviceId[PRODUCTKEY_MAXLEN + DEVICENAME_MAXLEN + 2] = {0}; char macSrc[SIGN_SOURCE_MAXLEN] = {0}; uint8_t macRes[32] = {0}; int res; /* check parameters */ if (productKey == NULL || deviceName == NULL || deviceSecret == NULL || clientId == NULL || username == NULL || password == NULL) { return -1; } if ((strlen(productKey) > PRODUCTKEY_MAXLEN) || (strlen(deviceName) > DEVICENAME_MAXLEN) || (strlen(deviceSecret) > DEVICESECRET_MAXLEN)) { return -1; } /* setup deviceId */ memcpy(deviceId, deviceName, strlen(deviceName)); memcpy(deviceId + strlen(deviceId), "&", strlen("&")); memcpy(deviceId + strlen(deviceId), productKey, strlen(productKey)); /* setup clientid */ memcpy(clientId, deviceId, strlen(deviceId)); memcpy(clientId + strlen(deviceId), MQTT_CLINETID_KV, strlen(MQTT_CLINETID_KV)); memset(clientId + strlen(deviceId) + strlen(MQTT_CLINETID_KV), 0, 1); /* setup username */ memcpy(username, deviceId, strlen(deviceId)); memset(username + strlen(deviceId), 0, 1); /* setup password */ memcpy(macSrc, "clientId", strlen("clientId")); memcpy(macSrc + strlen(macSrc), deviceId, strlen(deviceId)); memcpy(macSrc + strlen(macSrc), "deviceName", strlen("deviceName")); memcpy(macSrc + strlen(macSrc), deviceName, strlen(deviceName)); memcpy(macSrc + strlen(macSrc), "productKey", strlen("productKey")); memcpy(macSrc + strlen(macSrc), productKey, strlen(productKey)); memcpy(macSrc + strlen(macSrc), "timestamp", strlen("timestamp")); memcpy(macSrc + strlen(macSrc), TIMESTAMP_VALUE, strlen(TIMESTAMP_VALUE)); utils_hmac_sha256((uint8_t *)macSrc, strlen(macSrc), (uint8_t *)deviceSecret, strlen(deviceSecret), macRes); memset(password, 0, PASSWORD_MAXLEN); _hex2str(macRes, sizeof(macRes), password); return 0; } /****************************** * hmac-sha256 implement below ******************************/ #define SHA256_KEY_IOPAD_SIZE (64) #define SHA256_DIGEST_SIZE (32) /** * \brief SHA-256 context structure */ typedef struct { uint32_t total[2]; /*!< number of bytes processed */ uint32_t state[8]; /*!< intermediate digest state */ unsigned char buffer[64]; /*!< data block being processed */ int is224; /*!< 0 => SHA-256, else SHA-224 */ } iot_sha256_context; typedef union { char sptr[8]; uint64_t lint; } u_retLen; /* * 32-bit integer manipulation macros (big endian) */ #ifndef GET_UINT32_BE #define GET_UINT32_BE(n,b,i) \ do { \ (n) = ( (uint32_t) (b)[(i) ] << 24 ) \ | ( (uint32_t) (b)[(i) + 1] << 16 ) \ | ( (uint32_t) (b)[(i) + 2] << 8 ) \ | ( (uint32_t) (b)[(i) + 3] ); \ } while( 0 ) #endif #ifndef PUT_UINT32_BE #define PUT_UINT32_BE(n,b,i) \ do { \ (b)[(i) ] = (unsigned char) ( (n) >> 24 ); \ (b)[(i) + 1] = (unsigned char) ( (n) >> 16 ); \ (b)[(i) + 2] = (unsigned char) ( (n) >> 8 ); \ (b)[(i) + 3] = (unsigned char) ( (n) ); \ } while( 0 ) #endif static void utils_sha256_zeroize(void *v, uint32_t n) { volatile unsigned char *p = v; while (n--) { *p++ = 0; } } void utils_sha256_init(iot_sha256_context *ctx) { memset(ctx, 0, sizeof(iot_sha256_context)); } void utils_sha256_free(iot_sha256_context *ctx) { if (NULL == ctx) { return; } utils_sha256_zeroize(ctx, sizeof(iot_sha256_context)); } void utils_sha256_starts(iot_sha256_context *ctx) { int is224 = 0; ctx->total[0] = 0; ctx->total[1] = 0; if (is224 == 0) { /* SHA-256 */ ctx->state[0] = 0x6A09E667; ctx->state[1] = 0xBB67AE85; ctx->state[2] = 0x3C6EF372; ctx->state[3] = 0xA54FF53A; ctx->state[4] = 0x510E527F; ctx->state[5] = 0x9B05688C; ctx->state[6] = 0x1F83D9AB; ctx->state[7] = 0x5BE0CD19; } ctx->is224 = is224; } static const uint32_t K[] = { 0x428A2F98, 0x71374491, 0xB5C0FBCF, 0xE9B5DBA5, 0x3956C25B, 0x59F111F1, 0x923F82A4, 0xAB1C5ED5, 0xD807AA98, 0x12835B01, 0x243185BE, 0x550C7DC3, 0x72BE5D74, 0x80DEB1FE, 0x9BDC06A7, 0xC19BF174, 0xE49B69C1, 0xEFBE4786, 0x0FC19DC6, 0x240CA1CC, 0x2DE92C6F, 0x4A7484AA, 0x5CB0A9DC, 0x76F988DA, 0x983E5152, 0xA831C66D, 0xB00327C8, 0xBF597FC7, 0xC6E00BF3, 0xD5A79147, 0x06CA6351, 0x14292967, 0x27B70A85, 0x2E1B2138, 0x4D2C6DFC, 0x53380D13, 0x650A7354, 0x766A0ABB, 0x81C2C92E, 0x92722C85, 0xA2BFE8A1, 0xA81A664B, 0xC24B8B70, 0xC76C51A3, 0xD192E819, 0xD6990624, 0xF40E3585, 0x106AA070, 0x19A4C116, 0x1E376C08, 0x2748774C, 0x34B0BCB5, 0x391C0CB3, 0x4ED8AA4A, 0x5B9CCA4F, 0x682E6FF3, 0x748F82EE, 0x78A5636F, 0x84C87814, 0x8CC70208, 0x90BEFFFA, 0xA4506CEB, 0xBEF9A3F7, 0xC67178F2, }; #define SHR(x,n) ((x & 0xFFFFFFFF) >> n) #define ROTR(x,n) (SHR(x,n) | (x << (32 - n))) #define S0(x) (ROTR(x, 7) ^ ROTR(x,18) ^ SHR(x, 3)) #define S1(x) (ROTR(x,17) ^ ROTR(x,19) ^ SHR(x,10)) #define S2(x) (ROTR(x, 2) ^ ROTR(x,13) ^ ROTR(x,22)) #define S3(x) (ROTR(x, 6) ^ ROTR(x,11) ^ ROTR(x,25)) #define F0(x,y,z) ((x & y) | (z & (x | y))) #define F1(x,y,z) (z ^ (x & (y ^ z))) #define R(t) \ ( \ W[t] = S1(W[t - 2]) + W[t - 7] + \ S0(W[t - 15]) + W[t - 16] \ ) #define P(a,b,c,d,e,f,g,h,x,K) \ { \ temp1 = h + S3(e) + F1(e,f,g) + K + x; \ temp2 = S2(a) + F0(a,b,c); \ d += temp1; h = temp1 + temp2; \ } void utils_sha256_process(iot_sha256_context *ctx, const unsigned char data[64]) { uint32_t temp1, temp2, W[64]; uint32_t A[8]; unsigned int i; for (i = 0; i < 8; i++) { A[i] = ctx->state[i]; } for (i = 0; i < 64; i++) { if (i < 16) { GET_UINT32_BE(W[i], data, 4 * i); } else { R(i); } P(A[0], A[1], A[2], A[3], A[4], A[5], A[6], A[7], W[i], K[i]); temp1 = A[7]; A[7] = A[6]; A[6] = A[5]; A[5] = A[4]; A[4] = A[3]; A[3] = A[2]; A[2] = A[1]; A[1] = A[0]; A[0] = temp1; } for (i = 0; i < 8; i++) { ctx->state[i] += A[i]; } } void utils_sha256_update(iot_sha256_context *ctx, const unsigned char *input, uint32_t ilen) { size_t fill; uint32_t left; if (ilen == 0) { return; } left = ctx->total[0] & 0x3F; fill = 64 - left; ctx->total[0] += (uint32_t) ilen; ctx->total[0] &= 0xFFFFFFFF; if (ctx->total[0] < (uint32_t) ilen) { ctx->total[1]++; } if (left && ilen >= fill) { memcpy((void *)(ctx->buffer + left), input, fill); utils_sha256_process(ctx, ctx->buffer); input += fill; ilen -= fill; left = 0; } while (ilen >= 64) { utils_sha256_process(ctx, input); input += 64; ilen -= 64; } if (ilen > 0) { memcpy((void *)(ctx->buffer + left), input, ilen); } } static const unsigned char sha256_padding[64] = { 0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; void utils_sha256_finish(iot_sha256_context *ctx, uint8_t output[32]) { uint32_t last, padn; uint32_t high, low; unsigned char msglen[8]; high = (ctx->total[0] >> 29) | (ctx->total[1] << 3); low = (ctx->total[0] << 3); PUT_UINT32_BE(high, msglen, 0); PUT_UINT32_BE(low, msglen, 4); last = ctx->total[0] & 0x3F; padn = (last < 56) ? (56 - last) : (120 - last); utils_sha256_update(ctx, sha256_padding, padn); utils_sha256_update(ctx, msglen, 8); PUT_UINT32_BE(ctx->state[0], output, 0); PUT_UINT32_BE(ctx->state[1], output, 4); PUT_UINT32_BE(ctx->state[2], output, 8); PUT_UINT32_BE(ctx->state[3], output, 12); PUT_UINT32_BE(ctx->state[4], output, 16); PUT_UINT32_BE(ctx->state[5], output, 20); PUT_UINT32_BE(ctx->state[6], output, 24); if (ctx->is224 == 0) { PUT_UINT32_BE(ctx->state[7], output, 28); } } void utils_sha256(const uint8_t *input, uint32_t ilen, uint8_t output[32]) { iot_sha256_context ctx; utils_sha256_init(&ctx); utils_sha256_starts(&ctx); utils_sha256_update(&ctx, input, ilen); utils_sha256_finish(&ctx, output); utils_sha256_free(&ctx); } static void utils_hmac_sha256(const uint8_t *msg, uint32_t msg_len, const uint8_t *key, uint32_t key_len, uint8_t output[32]) { iot_sha256_context context; uint8_t k_ipad[SHA256_KEY_IOPAD_SIZE]; /* inner padding - key XORd with ipad */ uint8_t k_opad[SHA256_KEY_IOPAD_SIZE]; /* outer padding - key XORd with opad */ int32_t i; if ((NULL == msg) || (NULL == key) || (NULL == output)) { return; } if (key_len > SHA256_KEY_IOPAD_SIZE) { return; } /* start out by storing key in pads */ memset(k_ipad, 0, sizeof(k_ipad)); memset(k_opad, 0, sizeof(k_opad)); memcpy(k_ipad, key, key_len); memcpy(k_opad, key, key_len); /* XOR key with ipad and opad values */ for (i = 0; i < SHA256_KEY_IOPAD_SIZE; i++) { k_ipad[i] ^= 0x36; k_opad[i] ^= 0x5c; } /* perform inner SHA */ utils_sha256_init(&context); /* init context for 1st pass */ utils_sha256_starts(&context); /* setup context for 1st pass */ utils_sha256_update(&context, k_ipad, SHA256_KEY_IOPAD_SIZE); /* start with inner pad */ utils_sha256_update(&context, msg, msg_len); /* then text of datagram */ utils_sha256_finish(&context, output); /* finish up 1st pass */ /* perform outer SHA */ utils_sha256_init(&context); /* init context for 2nd pass */ utils_sha256_starts(&context); /* setup context for 2nd pass */ utils_sha256_update(&context, k_opad, SHA256_KEY_IOPAD_SIZE); /* start with outer pad */ utils_sha256_update(&context, output, SHA256_DIGEST_SIZE); /* then results of 1st hash */ utils_sha256_finish(&context, output); /* finish up 2nd pass */ }
aiot_c_demo.c 这是你主要编写的代码，你可以参考我下面的
#include <stdio.h>
#include <memory.h>
#include "MQTTClient.h"
#include <stdio.h>
#include <signal.h>
#include <sys/time.h>
#define Aliyun
#define EXAMPLE_PRODUCT_KEY "a11B0MP4tDp"
#define EXAMPLE_DEVICE_NAME "1st_device_mqttfx"
#define EXAMPLE_DEVICE_SECRET "04dfa2d5fe80a9d993e6c59d6523fe43"
/* declare the external function aiotMqttSign() */
extern int aiotMqttSign(const char *productKey, const char *deviceName, const char *deviceSecret,
char clientId[150], char username[65], char password[65]);
volatile int toStop = 0;
void cfinish(int sig)
{
signal(SIGINT, NULL);
toStop = 1;
}
/*-----------------------------------------------
printf("%*s", 10, s);
意思是输出字符串s，但至少占10个位置，不足的在字符串s左边补空格，这里等同于printf("%10s", s);
-----------------------------------------------*/
void messageArrived(MessageData* md)
{
MQTTMessage* message = md->message;
printf("\nmessageArrived!! \n");
printf("%.*s\t", md->topicName->lenstring.len, md->topicName->lenstring.data);
printf("%.*s\n", (int)message->payloadlen, (char*)message->payload);
}
/* main function */
int main(int argc, char** argv)
{
int rc = 0;
/* setup the buffer, it must big enough for aliyun IoT platform */
unsigned char buf[1000];
unsigned char readbuf[1000];
Network n;
MQTTClient c;
#ifdef Aliyun
char *host = EXAMPLE_PRODUCT_KEY".iot-as-mqtt.cn-shanghai.aliyuncs.com";
short port = 443;
const char *subTopic = "/"EXAMPLE_PRODUCT_KEY"/"EXAMPLE_DEVICE_NAME"/service/property/set";
const char *pubTopic = "/sys/"EXAMPLE_PRODUCT_KEY"/"EXAMPLE_DEVICE_NAME"/thing/event/property/post";
#else
char *host = "47.105.141.172"; // "test.mosquitto.org";
short port = 1883;
const char *subTopic = "guest/talk"; // "/publish/TEST/111";
const char *pubTopic = "guest/talk"; // "/publish/TEST/000";
#endif
/* invoke aiotMqttSign to generate mqtt connect parameters */
char clientId[150] = {0};
char username[65] = {0};
char password[65] = {0};
#ifdef Aliyun
if ((rc = aiotMqttSign(EXAMPLE_PRODUCT_KEY, EXAMPLE_DEVICE_NAME, EXAMPLE_DEVICE_SECRET, clientId, username, password) < 0)) {
printf("aiotMqttSign -%0x4x\n", -rc);
return -1;
}
printf("clientid: %s\n", clientId);
printf("username: %s\n", username);
printf("password: %s\n", password);
#endif
signal(SIGINT, cfinish);
signal(SIGTERM, cfinish);
/* network init and establish network to aliyun IoT platform */
NetworkInit(&n);
rc = NetworkConnect(&n, host, port);
printf("NetworkConnect %d\n", rc);
/* init mqtt client */
MQTTClientInit(&c, &n, 1000, buf, sizeof(buf), readbuf, sizeof(readbuf));
/* set the default message handler */
c.defaultMessageHandler = messageArrived;
/* set mqtt connect parameter */
MQTTPacket_connectData data = MQTTPacket_connectData_initializer;
data.willFlag = 0;
//data.MQTTVersion = 3; 版本号不要指定，要不然连接服务器(执行MQTTConnect时)会返回失败
data.clientID.cstring = clientId;
data.username.cstring = username;
data.password.cstring = password;
data.keepAliveInterval = 60;
data.cleansession = 1;
printf("Connecting to %s %d\n", host, port);
rc = MQTTConnect(&c, &data);
if(!rc)
printf("MQTTConnect %d, Connect aliyun IoT Cloud Success!\n", rc);
printf("Subscribing to %s\n", subTopic);
rc = MQTTSubscribe(&c, subTopic, 1, messageArrived);
printf("MQTTSubscribe %d\n", rc);
int cnt = 0;
unsigned int msgid = 0;
char mqttdata[] = {"{\"method\":\"thing.event.property.post\",\"id\":\"1371514638\",\"params\":{\"Humidity\":76},\"version\":\"1.0.0\"}"};
printf("mqttdata==> %s\n\n", mqttdata);
while (!toStop)
{
// MQTT_Yield会block住timeout的时间去尝试接收数据，直到timeout才会退出
MQTTYield(&c, 1000); // 在需要接收数据时, 都需要主动调用该函数
if (++cnt % 20 == 0) { // every 5 seconds, will do this
MQTTMessage msg = {
QOS0,
1, // 0 ?
0,
0,
mqttdata,
strlen(mqttdata),
};
msg.id = ++msgid;
rc = MQTTPublish(&c, pubTopic, &msg);
printf("MQTTPublish %d, msgid %d\n", rc, msgid);
}
}
printf("Stopping\n");
MQTTDisconnect(&c);
NetworkDisconnect(&n);
return 0;
}
结果
.
/************* 社会的有色眼光是：博士生、研究生、本科生、车间工人; 重点大学高材生、普通院校、二流院校、野鸡大学; 年薪百万、五十万、五万; 这些都只是帽子,可以失败千百次，但我和社会都觉得，人只要成功一次，就能换一顶帽子，只是社会看不见你之前的失败的帽子。 当然，换帽子决不是最终目的，走好自己的路就行。 杭州.大话西游 *******/
