5-Openwrt MQTT client使用

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creator_ly 2022-01-07 10:10:03 博主文章分类：Mqtt ©著作权

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mosquitto已经集成了命令行mosquitto_sub和mosquitto_pub，这个一般就是调试的时候使用，后面还是要使用mosquitto提供的库函数实现C语言代码层的客户端。

1. 添加client

在mosquitto里面有个client目录，里面就是使用libmosquitto实现的客户端程序，封装成mosquitto_sub和mosquitto_pub命令行。

所以新建一个跟client同一级，自己的client，添加对应的文件

tree myclient/
myclient/
├── main.c
├── Makefile
└── myclient.h

0 directories, 3 files

Makefile的内容

include ../config.mk

.PHONY: all install uninstall reallyclean clean

all : myclient

myclient : main.o
  ${CROSS_COMPILE}${CC} $^ -o $@ ${CLIENT_LDFLAGS} -lpthread

main.o : main.c ../lib/libmosquitto.so.${SOVERSION}
  ${CROSS_COMPILE}${CC} -c $< -o $@ ${CLIENT_CFLAGS}

../lib/libmosquitto.so.${SOVERSION} :
  $(MAKE) -C ../lib

../lib/libmosquitto.a :
  $(MAKE) -C ../lib libmosquitto.a

install : all
  $(INSTALL) -d "${DESTDIR}$(prefix)/bin"
  $(INSTALL) ${STRIP_OPTS} myclient "${DESTDIR}${prefix}/bin/myclient"

uninstall :
  -rm -f "${DESTDIR}${prefix}/bin/myclient"

reallyclean : clean

clean : 
  -rm -f *.o myclient

main.c的内容

#include <stdio.h>
#include <signal.h>
#include <pthread.h>
#include <mosquitto.h>
#include "myclient.h"

int debugLevel = MSG_INFO;

int main (int argc, char **argv)
{
    dbg_printf(MSG_DEBUG, "start...\r\n");
    return 0;
}

myclient.h的内容

#ifndef MYCLIENT_H
#define MYCLIENT_H

#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>

extern int debugLevel;

enum{
    MSG_ERROR,
    MSG_WARNING,
    MSG_INFO,
    MSG_DEBUG,
    MSG_MSGDUMP,
    MSG_EXCESSIVE,
};

#define dbg_printf(level, ...)                      \
do                                                  \
{                                                   \
    if (debugLevel >= level)                         \
    {                                               \
        syslog(LOG_WARNING, __VA_ARGS__);           \
    }                                               \
}                                                   \
while (0)
//printf(__VA_ARGS__);

#endif

外层的mosquitto/src/Makefile里面添加myclient文件的编译

DIRS=lib client src myclient

编译测试一切正常，接下去添加mqtt的内容

2. 添加mqtt订阅test1，发布test2

mqtt client里面最主要的就是几个回调函数，先调用lib_init,正常后，就这只各个callback，然后在callback里面做逻辑。

int main (int argc, char **argv)
{
    int rc;

    mosquitto_lib_init();  //初始化库

    mosq = mosquitto_new("client_name", CLEAN_SESSION, NULL);  //创建一个客户端实例
    if(!mosq){
        mosquitto_lib_cleanup();
        return 1;
    }
    mosquitto_log_callback_set(mosq, myclient_log_callback);  //打印与broker的交互log
    mosquitto_connect_callback_set(mosq, myclient_connect_callback);  //连接成功的回调函数
    mosquitto_disconnect_callback_set(mosq, myclient_disconnect_callback);  //离线的回调函数
    mosquitto_message_callback_set(mosq, myclient_message_callback);  //收到消息的回调函数
    mosquitto_subscribe_callback_set(mosq, myclient_subscribe_callback);  //订阅成功的回调函数
    mosquitto_reconnect_delay_set(mosq, RECONNECT_DELAY, RECONNECT_DELAY_MAX, RECONNECT_EXPONENTIAL_BACKOFF);  //设置离线后重连时间

    dbg_printf(MSG_INFO, "start connect\n");
    while(mosquitto_connect(mosq, BROKER_NAME, BROKER_PORT, BROKER_TIMEOUT) != MOSQ_ERR_SUCCESS) {
        dbg_printf(MSG_ERROR, "AC Client connect faild\r\n");
        sleep(5);
    }  //开始连接

    rc = mosquitto_loop_forever(mosq, -1, 1);  //循环，事件触发到各自的回调函数里面

out:
    dbg_printf(MSG_ERROR, "loop error %d\r\n", rc);

    mosquitto_destroy(mosq);
    mosquitto_lib_cleanup();

    mosq = NULL;

    if(rc){
        fprintf(stderr, "Subscribe Error: %s\n", mosquitto_strerror(rc));
    }

    return 0;
}

各回调函数的内容

static void publish_test2_msg(void)
{
    int mid = 0;
    char payload[32] = "\"test2\":\"1111\"";

    mosquitto_publish(mosq, &mid, TOPIC_TEST2, strlen(payload), payload, TOPIC_QOS, false);

}

static void myclient_message_callback(struct mosquitto *mosq, void *obj, const struct mosquitto_message *message)
{
    if (message->payloadlen) {

        dbg_printf(MSG_DEBUG, "收到主题:%s\r\n", message->topic);
        dbg_printf(MSG_DEBUG, "收到消息:%s, 消息长度:%d\r\n", message->payload, message->payloadlen);
    }

    return;
}

static void myclient_subscribe_callback(struct mosquitto *mosq, void *obj, int mid, int qos_count, const int *granted_qos)
{
    dbg_printf(MSG_DEBUG, "Subscribed (mid: %d): %d\r\n", mid, granted_qos[0]);
}

static void myclient_log_callback(struct mosquitto *mosq, void *obj, int level, const char *str)
{
    dbg_printf(MSG_DEBUG, "%s\r\n", str);
}

static void myclient_connect_callback(struct mosquitto *mosq, void *obj, int result)
{
    if(!result) {
        dbg_printf(MSG_INFO, "connect ok\n");
        mosquitto_subscribe(mosq, NULL, TOPIC_TEST1, TOPIC_QOS);
        publish_test2_msg();
    }
}

static void myclient_disconnect_callback(struct mosquitto *mosq, void *obj, int result)
{
    dbg_printf(MSG_WARNING, "connect lost\r\n");
}

逻辑应该也比较直观，当connect成功后，在回调函数里面订阅test1主题的内容，然后发布test2主题的内容。

收到内容就在myclient_message_callback回调里面打印处理。

3. 账号密码登录

正常情况我们都会让客户端的连接做一些账号密码的设置，避免别人攻击。

3.1 默认方式添加账号密码

将allow_anonymous改成不允许匿名登陆，并制定pwfile。

vim /etc/mosquittoConf/mosquitto.conf

allow_anonymous false
password_file /etc/mosquittoConf/pwfile

在ubuntu上面使用mosquitto_passwd生成密码

mosquitto_passwd -c /home/linye/mqtt/pwfile root
Password:
Reenter password:

就会在pwfile文件下生成账号和加密的密码root/admin

cat ~/mqtt/pwfile
root:$6$Mf+7EtctNlbTlwvV$IYYMsLiGos6OLwxCzYRKOOEilm5haU/K88ChsYDsru/oj2S8dn9XL4B4XX/CkdY9TIp5GcU5g7WziNd5lxVD/w==

这是后登陆的时候就需要-u root -P admin进行登陆

osquitto_sub  -c -h 127.0.0.1 -p 1883 -k 30 -t /local/test1
cacert.pem -u root -P admin
start connect
connect ok

3.2 自定义方式添加账号密码

mosquitto提供了mosquitto_passwd命令来生成账号密码等，不过这个方式不喜欢，因为没办法定制化自己想要的账号密码加密方式，所以做了一些小改动。

在myclient里面加我们想要的加密方式，然后在mosquitto broker的源码里面添加对应的解密方式即可。

如下，账号为client_name，然后通过rsa和base64生成密码，myclient的试下调用mosquitto_username_pw_set函数。

static void myclient_set_username_pw(struct mosquitto *mosq)
{
    unsigned char *username_rsa = NULL;
    unsigned char *username_base64 = NULL;

    username_rsa = rsa_encrypt(client_name);
    if(username_rsa){
        username_base64 = base64_encode(username_rsa, RSA_LENGTH);
    }

    if(username_base64){
        mosquitto_username_pw_set(mosq, client_name, username_base64);
    }

    if(username_rsa){
        free(username_rsa);
        username_rsa = NULL;
    }

    if(username_base64){
        free(username_base64);
        username_base64 = NULL;
    }
}

然后在mosquitto broker里面添加解密，位于mosquitto/src/security.c文件的mosquitto_unpwd_check函数里面。

int mosquitto_myclient_auth_unpwd_check(struct mosquitto *context,const char *username, const char *password)
{    
    if(context->address == NULL)
        return MOSQ_ERR_AUTH;

    int rc = MOSQ_ERR_AUTH;
    unsigned char *user_rsa =NULL;
    unsigned char *user =NULL;

    user_rsa = base64_decode(password);
    if(user_rsa){
        user = rsa_decrypt(user_rsa);
    }

    if(user){
        if(!strcmp(user, username)){
            rc = MOSQ_ERR_SUCCESS;
        }
        else{
            rc = MOSQ_ERR_AUTH;
        }
    }

    if(user_rsa){
        free(user_rsa);
        user_rsa = NULL;
    }

    if(user){
        free(user);
        user = NULL;
    }

    return rc;

}

int mosquitto_unpwd_check(struct mosquitto_db *db, struct mosquitto *context, const char *username, const char *password)
{
    int rc;
    int i;
    struct mosquitto__security_options *opts;

    rc = mosquitto_unpwd_check_default(db, context, username, password);
    if(rc != MOSQ_ERR_PLUGIN_DEFER){
        return rc;
    }
    ...

    rc = mosquitto_myclient_auth_unpwd_check(context, username, password);

    ...
    return rc;
}

4. SSL认证

另一个加密方式就是SSL认证，给客户端提供相应的证书，和配置协议(mqtt or websockets)一样，在配置文件监听的端口下面可以添加ssl的配置选项，每个port都可以单独配置ssl的证书内同容。

如下：从端口7885连接进来的设备需要下面的证书要求

port 7885

#CA证书文件
cafile /etc/mosquittoConf/cacert.pem
#PEM证书文件
certfile /etc/mosquittoConf/deviceCert.pem
#PEM密钥文件
keyfile /etc/mosquittoConf/deviceKey.pem

设备的认证有单向认证和双向认证两种：

不管单向还是双向，broker端都需要配置cafile、certfile、keyfile
单向的时候，client只需要提供cafile，双向的时候client需要提供cafile、certfile、keyfile
双向的时候，broker需要将require_certificate和use_identity_as_username设置成true

单向认证，只需要提供ca证书

mosquitto_sub -h 192.168.18.1 -p 6885 -t "local/iot/ziroom/broadcast" --cafile ~/mqtt/zgateway/cacert.pem --insecure

mosquitto_sub -h 192.168.18.1 -p 1883 -t "local/iot/ziroom/broadcast"

双向认证，需要ca,pem,key三个

mosquitto_sub -h 10.30.11.47 -p 8883 -t "local/test1" --cafile ./ca/ca.crt --cert ./client/client.pem --key ./client/client.key &

mosquitto_pub -h 10.30.11.47 -p 8883 -t "mqtt/server/topic" -m "hello,world!" --cafile ./ca/ca.crt --cert ./server/server.pem --key ./server/server.key

按步骤一步一步执行，生成证书（里面也可以指定各参数，有效时间）：

// ======================================================
//          SSL 
// ======================================================
openssl req -new -x509 -days 36500 -extensions v3_ca -keyout ca.key -out ca.crt
# PEM pass phrase: 123456
# Country Name: CH
# State Or Province Name: Shanghai
# Locality Name: Yangpu
# Organization Name: Fanyi
# Organizational Unit Name: Embed
# Common Name: 192.168.100.33
# Email Address: 916634969@qq.com

// 给mosquitto_server端
openssl genrsa -out server.key 2048
openssl req -out server.csr -key server.key -new
# Country Name: CH
# State Or Province Name: Shanghai
# Locality Name: Yangpu
# Organization Name: Fanyi
# Organizational Unit Name: Embed
# Common Name: 192.168.100.34
# Email Address: 916634969@qq.com
# A challenge password: 123456
# An optional company name: Fanyi
openssl x509 -req -in server.csr -CA ca.crt -CAkey ca.key -CAcreateserial -out server.crt -days 36500
# Enter pass phrase for ca.key: 123456

// 给mosquitto_client_sub端
openssl genrsa -out client_sub.key 2048
openssl req -out client_sub.csr -key client_sub.key -new
# Country Name: CH
# State Or Province Name: Shanghai
# Locality Name: Yangpu
# Organization Name: Fanyi
# Organizational Unit Name: Embed
# Common Name: 192.168.100.40
# Email Address: 916634969@qq.com
# A challenge password: 123456
# An optional company name: Fanyi
openssl x509 -req -in client_sub.csr -CA ca.crt -CAkey ca.key -CAcreateserial -out client_sub.crt -days 36500
# Enter pass phrase for ca.key: 123456

// 给mosquitto_client_pub端
openssl genrsa -out client_pub.key 2048
openssl req -out client_pub.csr -key client_pub.key -new
# Country Name: CH
# State Or Province Name: Shanghai
# Locality Name: Yangpu
# Organization Name: Fanyi
# Organizational Unit Name: Embed
# Common Name: 192.168.100.41
# Email Address: 916634969@qq.com
# A challenge password: 123456
# An optional company name: Fanyi
openssl x509 -req -in client_pub.csr -CA ca.crt -CAkey ca.key -CAcreateserial -out client_pub.crt -days 36500
# Enter pass phrase for ca.key: 123456

// 验证生成的服务端和客户端的证书是否可用
openssl verify -CAfile /home/ares/mqtt/server_ssl/ca.crt /home/ares/mqtt/server_ssl/server.crt
openssl verify -CAfile /home/ares/mqtt/client_sub_ssl/ca.crt /home/ares/mqtt/client_sub_ssl/client_sub.crt
openssl verify -CAfile /home/ares/mqtt/client_pub_ssl/ca.crt /home/ares/mqtt/client_pub_ssl/client_pub.crt
————————————————

按上面的步骤可以生成如下文件

ubuntu:~/mqtt/ssl$ ls
ca.crt  client_pub.crt  client_sub.crt  server.crt
ca.key  client_pub.csr  client_sub.csr  server.csr
ca.srl  client_pub.key  client_sub.key  server.key

在服务器端需要放三个文件

ca.crt即cafile
server.crt即certfile
server.key即keyfile

如果是单向认证，客户端只需要一个文件

ca.crt即cafile

如果是双向认证，客户端只需要三个文件

ca.crt即cafile
client.crt即certfile
client.key即keyfile

查看证书的有效时间

ubuntu:~$ openssl x509 -in cacert.pem -noout -dates
notBefore=Apr 23 12:40:56 2019 GMT
notAfter=Apr 19 12:40:56 2032 GMT

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