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Wakaama 是lwm2m协议的一种实现，其源码路径为wakaama。lwm2m的实现分为server和client。编译server的方法为：cmake [wakaama directory]/examples/servermake./lwm2mserver [Options]我们看看server的makerfile是怎么写的#要求cmake的版本必须是2.8cmake_minimum_required (VERSION 2.8)project (lwm2mserver C)#不支持dtls特性if(DTLS) message(FATAL_ERROR "DTLS option is not supported." ) endif()include(${CMAKE_CURRENT_LIST_DIR}/../../core/wakaama.cmake) include(${CMAKE_CURRENT_LIST_DIR}/../shared/shared.cmake)#定义宏add_definitions(-DLWM2M_SERVER_MODE) add_definitions(${SHARED_DEFINITIONS} ${WAKAAMA_DEFINITIONS})include_directories (${WAKAAMA_SOURCES_DIR} ${SHARED_INCLUDE_DIRS})#原来server就一个源文件SET(SOURCES ${CMAKE_CURRENT_LIST_DIR}/lwm2mserver.c    )#编译成可执行文件add_executable(${PROJECT_NAME} ${SOURCES} ${WAKAAMA_SOURCES} ${SHARED_SOURCES})# Add WITH_LOGS to debug variant set_property(TARGET ${PROJECT_NAME} APPEND PROPERTY COMPILE_DEFINITIONS $<$
   
    :WITH_LOGS>)SOURCE_GROUP(wakaama FILES ${WAKAAMA_SOURCES}) 我们看看这个唯一的源文件的main函数int main(int argc, char *argv[]){    int sock;    fd_set readfds;    struct timeval tv;    int result;    lwm2m_context_t * lwm2mH = NULL;    int i;    connection_t * connList = NULL;    int addressFamily = AF_INET6;    int opt;    const char * localPort = LWM2M_STANDARD_PORT_STR;#main函数支持的子命令    command_desc_t commands[] =    {            {"list", "List registered clients.", NULL, prv_output_clients, NULL},            {"read", "Read from a client.", " read CLIENT# URI\r\n"                                            "   CLIENT#: client number as returned by command 'list'\r\n"                                            "   URI: uri to read such as /3, /3/0/2, /1024/11, /1024/0/1\r\n"                                            "Result will be displayed asynchronously.", prv_read_client, NULL},            {"disc", "Discover resources of a client.", " disc CLIENT# URI\r\n"                                            "   CLIENT#: client number as returned by command 'list'\r\n"                                            "   URI: uri to discover such as /3, /3/0/2, /1024/11, /1024/0/1\r\n"                                            "Result will be displayed asynchronously.", prv_discover_client, NULL},            {"write", "Write to a client.", " write CLIENT# URI DATA\r\n"                                            "   CLIENT#: client number as returned by command 'list'\r\n"                                            "   URI: uri to write to such as /3, /3/0/2, /1024/11, /1024/0/1\r\n"                                            "   DATA: data to write\r\n"                                            "Result will be displayed asynchronously.", prv_write_client, NULL},             };    opt = 1; {        if (argv[opt] == NULL            || argv[opt][0] != '-'            || argv[opt][2] != 0)        {            print_usage();            return 0;        }        switch (argv[opt][1])        {        case '4':            addressFamily = AF_INET;            break;        case 'l':            opt++;            if (opt >= argc)            {                print_usage();                return 0;            }            localPort = argv[opt];            break;        default:            print_usage();            return 0;        }        opt += 1;    }        #建立一个socket，默认是用AF_INET即netlinksock = create_socket(localPort, addressFamily);    if (sock < 0)    {        fprintf(stderr, "Error opening socket: %d\r\n", errno);        return -1;    }#初始化lwm2m    lwm2mH = lwm2m_init(NULL);    if (NULL == lwm2mH)    {        fprintf(stderr, "lwm2m_init() failed\r\n");        return -1;    }#设置信号量SIGNIT的回调函数    signal(SIGINT, handle_sigint);    for (i = 0 ; commands[i].name != NULL ; i++)    {        commands[i].userData = (void *)lwm2mH;    }    fprintf(stdout, "> "); fflush(stdout);    lwm2m_set_monitoring_callback(lwm2mH, prv_monitor_callback, lwm2mH);#看见main函数就是一个死循环，直到收到SIGINT信号后将g_quit修改成0 才退出.    while (0 == g_quit)    {        FD_ZERO(&readfds);        FD_SET(sock, &readfds);        FD_SET(STDIN_FILENO, &readfds);        tv.tv_sec = 60;        tv.tv_usec = 0;        result = lwm2m_step(lwm2mH, &(tv.tv_sec));        if (result != 0)        {            fprintf(stderr, "lwm2m_step() failed: 0x%X\r\n", result);            return -1;        }#最终要是这里开始调用select来监听client的通信        result = select(FD_SETSIZE, &readfds, 0, 0, &tv);#select发生错误的情况        if ( result < 0 )        {            if (errno != EINTR)            {              fprintf(stderr, "Error in select(): %d\r\n", errno);            }        }#select正常返回的情况        else if (result > 0)        {            uint8_t buffer[MAX_PACKET_SIZE];            int numBytes;#检查是否sock这个句柄被设置了            if (FD_ISSET(sock, &readfds))            {                struct sockaddr_storage addr;                socklen_t addrLen;                addrLen = sizeof(addr);#读取sock返回的信息                numBytes = recvfrom(sock, buffer, MAX_PACKET_SIZE, 0, (struct sockaddr *)&addr, &addrLen);                if (numBytes == -1)                {                    fprintf(stderr, "Error in recvfrom(): %d\r\n", errno);                }                else                {                    char s[INET6_ADDRSTRLEN];                    in_port_t port;                    connection_t * connP;			s[0] = 0;#判断netlink是ipv4还是ipv6，这里假定是ipv4                    if (AF_INET == addr.ss_family)                    {                        struct sockaddr_in *saddr = (struct sockaddr_in *)&addr;                        inet_ntop(saddr->sin_family, &saddr->sin_addr, s, INET6_ADDRSTRLEN);                        port = saddr->sin_port;                    }                    else if (AF_INET6 == addr.ss_family)                    {                        struct sockaddr_in6 *saddr = (struct sockaddr_in6 *)&addr;                        inet_ntop(saddr->sin6_family, &saddr->sin6_addr, s, INET6_ADDRSTRLEN);                        port = saddr->sin6_port;                    }                    fprintf(stderr, "%d bytes received from [%s]:%hu\r\n", numBytes, s, ntohs(port));#将数据读到buffer中                    output_buffer(stderr, buffer, numBytes, 0);#判断这个是新连接还是就连接                    connP = connection_find(connList, &addr, addrLen);                    if (connP == NULL)                    {#如果是新连接则建立连接后，将新连接保存到connlist中                        connP = connection_new_incoming(connList, sock, (struct sockaddr *)&addr, addrLen);                        if (connP != NULL)                        {                            connList = connP;                        }                    }                    if (connP != NULL)                    {#只要前面的连接有效，则开始处理client发送过来的包                        lwm2m_handle_packet(lwm2mH, buffer, numBytes, connP);                    }                }            }#如果是STDIN_FILENO 这个句柄被设置，则出来这个句柄中读到的command            else if (FD_ISSET(STDIN_FILENO, &readfds))            {                numBytes = read(STDIN_FILENO, buffer, MAX_PACKET_SIZE - 1);                if (numBytes > 1)                {                    buffer[numBytes] = 0;                    handle_command(commands, (char*)buffer);                    fprintf(stdout, "\r\n");                }                if (g_quit == 0)                {                    fprintf(stdout, "> ");                    fflush(stdout);                }                else                {                    fprintf(stdout, "\r\n");                }            }        }    }    lwm2m_close(lwm2mH);    close(sock);    connection_free(connList);#ifdef MEMORY_TRACE    if (g_quit == 1)    {        trace_print(0, 1);    }#endif    return 0;}
   

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