自学教程：C++ udp_recv函数代码示例

/** * Start UDP transfer. */static int udp_start(struct ttcp* ttcp) {	ttcp->udp_end_marker_left = 5;	ttcp->upcb = udp_new();	if (ttcp->upcb == NULL) {		printk("TTCP [%p]: could not allocate pcb/n", ttcp);		return -1;	}	if (ttcp->mode == TTCP_MODE_TRANSMIT) {		if (udp_connect(ttcp->upcb, &ttcp->addr, ttcp->port) != ERR_OK) {			printk("TTCP [%p]: udp connect failed/n", ttcp);			return -1;		}		udp_send_data(ttcp);	} else {		udp_recv(ttcp->upcb, udp_recv_cb, ttcp);	}	return 0;}

/**  * @brief  Processes TFTP write request  * @param  to: pointer on the receive IP address  * @param  to_port: receive port number  * @retval none  */static int IAP_tftp_process_write(struct udp_pcb *upcb, struct ip_addr *to, int to_port){  tftp_connection_args *args = NULL;  /* This function is called from a callback,  * therefore interrupts are disabled,  * therefore we can use regular malloc   */  args = mem_malloc(sizeof *args);  if (!args)  {    IAP_tftp_cleanup_wr(upcb, args);    return 0;  }  args->op = TFTP_WRQ;  args->to_ip.addr = to->addr;  args->to_port = to_port;  /* the block # used as a positive response to a WRQ is _always_ 0!!! (see RFC1350)  */  args->block = 0;  args->tot_bytes = 0;  /* set callback for receives on this UDP PCB (Protocol Control Block) */  udp_recv(upcb, IAP_wrq_recv_callback, args);    total_count =0;  /* init flash */  FLASH_If_Init();    /* erase user flash area */  FLASH_If_Erase(USER_FLASH_FIRST_PAGE_ADDRESS);   Flash_Write_Address = USER_FLASH_FIRST_PAGE_ADDRESS;      /* initiate the write transaction by sending the first ack */  IAP_tftp_send_ack_packet(upcb, to, to_port, args->block);  #ifdef USE_LCD  LCD_DisplayStringLine(Line9, (char*)"State: Programming.."); #endif    return 0;}

/*..........................................................................*/QState LwIPMgr_initial(LwIPMgr *me, QEvt const *e) {    uint8_t  macaddr[NETIF_MAX_HWADDR_LEN];    (void)e;        /* suppress the compiler warning about unused parameter */    /* Configure the hardware MAC address for the Ethernet Controller */    macaddr[0] = MAC_ADDR0;    macaddr[1] = MAC_ADDR1;    macaddr[2] = MAC_ADDR2;    macaddr[3] = MAC_ADDR3;    macaddr[4] = MAC_ADDR4;    macaddr[5] = MAC_ADDR5;                                          /* initialize the Ethernet Driver */    me->netif = eth_driver_init((QActive *)me, macaddr);    me->ip_addr = 0x00000000U;            /* initialize to impossible value */                                     /* initialize the lwIP applications... */    httpd_init();         /* initialize the simple HTTP-Deamon (web server) */    http_set_ssi_handler(&ssi_handler, ssi_tags, Q_DIM(ssi_tags));    http_set_cgi_handlers(cgi_handlers, Q_DIM(cgi_handlers));    me->upcb = udp_new();    udp_bind(me->upcb, IP_ADDR_ANY, 777U);          /* use port 777 for UDP */    udp_recv(me->upcb, &udp_rx_handler, me);    QS_OBJ_DICTIONARY(&l_lwIPMgr);    QS_OBJ_DICTIONARY(&l_lwIPMgr.te_LWIP_SLOW_TICK);    QS_FUN_DICTIONARY(&QHsm_top);    QS_FUN_DICTIONARY(&LwIPMgr_initial);    QS_FUN_DICTIONARY(&LwIPMgr_running);    QS_SIG_DICTIONARY(SEND_UDP_SIG,       (QActive *)me);    QS_SIG_DICTIONARY(LWIP_SLOW_TICK_SIG, (QActive *)me);    QS_SIG_DICTIONARY(LWIP_RX_READY_SIG,  (QActive *)me);    QS_SIG_DICTIONARY(LWIP_TX_READY_SIG,  (QActive *)me);    QS_SIG_DICTIONARY(LWIP_RX_OVERRUN_SIG,(QActive *)me);    return Q_TRAN(&LwIPMgr_connecting);}

/**  * @brief  Creates and initializes a UDP PCB for TFTP receive operation    * @param  none    * @retval none  */void IAP_tftpd_init(void){  err_t err;  unsigned port = 69; /* 69 is the port used for TFTP protocol initial transaction */  /* create a new UDP PCB structure  */  UDPpcb = udp_new();  if (!UDPpcb)  {    /* Error creating PCB. Out of Memory  */    return ;  }  /* Bind this PCB to port 69  */  err = udp_bind(UDPpcb, IP_ADDR_ANY, port);  if (err == ERR_OK)  {    /* Initialize receive callback function  */    udp_recv(UDPpcb, IAP_tftp_recv_callback, NULL);  } }

/** * Initialize this module. * Send out request instantly or after SNTP_STARTUP_DELAY. */voidsntp_init(int tz){  LWIP_DEBUGF(SNTP_DEBUG_WARN_STATE,"Sntp initializing TZ: GMT%s%02d.../n",tz > 0 ? "+" : "",tz);  ets_uart_printf("Sntp initializing.../n");  sntp_tz = tz;  if (sntp_pcb == NULL) {    os_timer_setfn(&ntp_timer,ntp_time_update,NULL);    SNTP_RESET_RETRY_TIMEOUT();    sntp_pcb = udp_new();    LWIP_ASSERT("Failed to allocate udp pcb for sntp client", sntp_pcb != NULL);    if (sntp_pcb != NULL) {      udp_recv(sntp_pcb, sntp_recv, NULL);#if SNTP_STARTUP_DELAY      sys_timeout((u32_t)SNTP_STARTUP_DELAY, sntp_request, NULL);#else      sntp_request(NULL);#endif    }  }}

/**  * @brief  Initialize the server application.  * @param  None  * @retval None  */void udp_echoserver_init(void){   struct udp_pcb *upcb;   err_t err;      /* Create a new UDP control block  */   upcb = udp_new();      if (upcb)   {     /* Bind the upcb to the UDP_PORT port */     /* Using IP_ADDR_ANY allow the upcb to be used by any local interface */      err = udp_bind(upcb, IP_ADDR_ANY, UDP_SERVER_PORT);            if(err == ERR_OK)      {        /* Set a receive callback for the upcb */        udp_recv(upcb, udp_echoserver_receive_callback, NULL);      }   }}

static socket_error_t lwipv4_socket_create(struct socket *sock, const socket_address_family_t af, const socket_proto_family_t pf, socket_api_handler_t const handler){    switch (af) {        case SOCKET_AF_INET4:            break;        default:            return SOCKET_ERROR_BAD_FAMILY;    }    if (sock == NULL || handler == NULL)        return SOCKET_ERROR_NULL_PTR;    switch (pf) {    case SOCKET_DGRAM:    {        struct udp_pcb *udp = udp_new();        if (udp == NULL)            return SOCKET_ERROR_BAD_ALLOC;        sock->stack = SOCKET_STACK_LWIP_IPV4;        sock->impl = (void *)udp;        udp_recv((struct udp_pcb *)sock->impl, irqUDPRecv, (void *)sock);        break;    }    case SOCKET_STREAM:    {      struct tcp_pcb *tcp = tcp_new();      if (tcp == NULL)        return SOCKET_ERROR_BAD_ALLOC;      sock->impl = (void *)tcp;      sock->stack = SOCKET_STACK_LWIP_IPV4;      tcp_arg(tcp, (void*) sock);      tcp_err(tcp, tcp_error_handler);      break;    }    default:        return SOCKET_ERROR_BAD_FAMILY;    }    sock->family = pf;    sock->handler = (void*)handler;    sock->rxBufChain = NULL;    return SOCKET_ERROR_NONE;}

void udp_echo_init(void){    struct udp_pcb * pcb;    // get new pcb    pcb = udp_new();    if (pcb == NULL) {        LWIP_DEBUGF(UDP_DEBUG, ("udp_new failed!/n"));        return;    }    // bind to any IP address on port 7    if (udp_bind(pcb, IP_ADDR_ANY, 7) != ERR_OK) {        LWIP_DEBUGF(UDP_DEBUG, ("udp_bind failed!/n"));        return;    }    printf("UDP bind to PORT:7 OK!/r/n");    // set udp_echo_recv() as callback function    // for received packets    udp_recv(pcb, udp_echo_recv, NULL);}

/**  * @brief  processes tftp write operation  * @param  upcb: pointer on upd pcb   * @param  to: pointer on remote IP address  * @param  to_port: pointer on remote udp port  * @param  FileName: pointer on filename to be written   * @retval error code  */int tftp_process_write(struct udp_pcb *upcb, struct ip_addr *to, int to_port, char *FileName){  tftp_connection_args *args = NULL;  /* Can not create file */  if (f_open(&file_CR, (const TCHAR*)FileName, FA_CREATE_ALWAYS|FA_WRITE) != FR_OK)  {    tftp_send_error_message(upcb, to, to_port, TFTP_ERR_NOTDEFINED);    tftp_cleanup_wr(upcb, args);    return 0;  }  args = mem_malloc(sizeof *args);  if (!args)  {    tftp_send_error_message(upcb, to, to_port, TFTP_ERR_NOTDEFINED);    tftp_cleanup_wr(upcb, args);    return 0;  }  args->op = TFTP_WRQ;  args->to_ip.addr = to->addr;  args->to_port = to_port;  /* the block # used as a positive response to a WRQ is _always_ 0!!! (see RFC1350)  */  args->block = 0;  args->tot_bytes = 0;  /* set callback for receives on this UDP PCB  */  udp_recv(upcb, wrq_recv_callback, args);  /* initiate the write transaction by sending the first ack */  tftp_send_ack_packet(upcb, to, to_port, args->block);  return 0;}

/**  * @brief  Creates and initializes a UDP PCB for TFTP receive operation    * @param  none    * @retval none  */void IAP_tftpd_init(void){  err_t err;  unsigned port = 69; /* 69 is the port used for TFTP protocol initial transaction */  /* create a new UDP PCB structure  */  UDPpcb = udp_new();  if (!UDPpcb)  {	udp_lcd_y += UPDATE_WORD_SIZE + UPDATE_ROW_DISTANCE;	lcd_font24(udp_lcd_x,udp_lcd_y,COLOR_POINT,COLOR_BACK,"> 
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