HAL配置tcp服务器
#include "lwip/debug.h" #include "lwip/stats.h" #include "lwip/tcp.h" #include "usart.h" #if LWIP_TCP static struct tcp_pcb *tcp_echoserver_pcb; /* ECHO protocol states */ enum tcp_echoserver_states { ES_NONE = 0, ES_ACCEPTED, ES_RECEIVED, ES_CLOSING }; /* structure for maintaing connection infos to be passed as argument to LwIP callbacks*/ struct tcp_echoserver_struct { u8_t state; /* current connection state */ u8_t retries; struct tcp_pcb *pcb; /* pointer on the current tcp_pcb */ struct pbuf *p; /* pointer on the received/to be transmitted pbuf */ }; static err_t tcp_echoserver_accept(void *arg, struct tcp_pcb *newpcb, err_t err); static err_t tcp_echoserver_recv(void *arg, struct tcp_pcb *tpcb, struct pbuf *p, err_t err); static void tcp_echoserver_error(void *arg, err_t err); static err_t tcp_echoserver_poll(void *arg, struct tcp_pcb *tpcb); static err_t tcp_echoserver_sent(void *arg, struct tcp_pcb *tpcb, u16_t len); static void tcp_echoserver_send(struct tcp_pcb *tpcb, struct tcp_echoserver_struct *es); static void tcp_echoserver_connection_close(struct tcp_pcb *tpcb, struct tcp_echoserver_struct *es); /** * @brief Initializes the tcp echo server * @param None * @retval None */ void tcp_echoserver_init(void) { /* create new tcp pcb */ tcp_echoserver_pcb = tcp_new(); if (tcp_echoserver_pcb != NULL) { err_t err; /* bind echo_pcb to port 7 (ECHO protocol) */ err = tcp_bind(tcp_echoserver_pcb, IP_ADDR_ANY, 7); if (err == ERR_OK) { /* start tcp listening for echo_pcb */ tcp_echoserver_pcb = tcp_listen(tcp_echoserver_pcb); printf("开始监听 \r\n"); /* initialize LwIP tcp_accept callback function */ tcp_accept(tcp_echoserver_pcb, tcp_echoserver_accept); printf("挂载客户端连接回调函数 \r\n"); } else { /* deallocate the pcb */ memp_free(MEMP_TCP_PCB, tcp_echoserver_pcb); printf("TCP PCB 内存申请失败 \r\n"); } } } /** * @brief This function is the implementation of tcp_accept LwIP callback * @param arg: not used * @param newpcb: pointer on tcp_pcb struct for the newly created tcp connection * @param err: not used * @retval err_t: error status */ static err_t tcp_echoserver_accept(void *arg, struct tcp_pcb *newpcb, err_t err) { err_t ret_err; struct tcp_echoserver_struct *es; LWIP_UNUSED_ARG(arg); LWIP_UNUSED_ARG(err); /* set priority for the newly accepted tcp connection newpcb */ tcp_setprio(newpcb, TCP_PRIO_MIN); printf("收到客户端连接请求，设置刚连接的客户端为最低优先级 \r\n"); uint8_t iptxt[20]; sprintf((char *)iptxt, "%s", ip4addr_ntoa((const ip4_addr_t *)&newpcb->remote_ip)); printf ("客户端 IP address: %s\r\n", iptxt); /* allocate structure es to maintain tcp connection informations */ es = (struct tcp_echoserver_struct *)mem_malloc(sizeof(struct tcp_echoserver_struct)); if (es != NULL) { es->state = ES_ACCEPTED; es->pcb = newpcb; es->retries = 0; es->p = NULL; printf("为新连接的客户端挂载需要的回调函数及 调用参数 \r\n"); /* pass newly allocated es structure as argument to newpcb */ tcp_arg(newpcb, es); /* initialize lwip tcp_recv callback function for newpcb */ tcp_recv(newpcb, tcp_echoserver_recv); /* initialize lwip tcp_err callback function for newpcb */ tcp_err(newpcb, tcp_echoserver_error); /* initialize lwip tcp_poll callback function for newpcb */ tcp_poll(newpcb, tcp_echoserver_poll, 0); ret_err = ERR_OK; } else { /* close tcp connection */ tcp_echoserver_connection_close(newpcb, es); printf("tcp_echoserver_struct 内存申请失败 关闭连接 \r\n"); /* return memory error */ ret_err = ERR_MEM; } return ret_err; } /** * @brief This function is the implementation for tcp_recv LwIP callback * @param arg: pointer on a argument for the tcp_pcb connection * @param tpcb: pointer on the tcp_pcb connection * @param pbuf: pointer on the received pbuf * @param err: error information regarding the reveived pbuf * @retval err_t: error code */ static err_t tcp_echoserver_recv(void *arg, struct tcp_pcb *tpcb, struct pbuf *p, err_t err) { struct tcp_echoserver_struct *es; err_t ret_err; LWIP_ASSERT("arg != NULL",arg != NULL); printf("收到客户端数据\r\n"); es = (struct tcp_echoserver_struct *)arg; /* if we receive an empty tcp frame from client => close connection */ if (p == NULL) { printf("收到断开连接请求 \r\n"); /* remote host closed connection */ es->state = ES_CLOSING; if(es->p == NULL) { /* we're done sending, close connection */ tcp_echoserver_connection_close(tpcb, es); } else { printf("发送的数据还未发送完成 \r\n"); /* we're not done yet */ /* acknowledge received packet */ tcp_sent(tpcb, tcp_echoserver_sent); printf("装载发送完成回调函数 \r\n"); /* send remaining data*/ tcp_echoserver_send(tpcb, es); } ret_err = ERR_OK; } /* else : a non empty frame was received from client but for some reason err != ERR_OK */ else if(err != ERR_OK) { /* free received pbuf*/ if (p != NULL) { es->p = NULL; pbuf_free(p); } ret_err = err; } else if(es->state == ES_ACCEPTED) { /* first data chunk in p->payload */ es->state = ES_RECEIVED; /* store reference to incoming pbuf (chain) */ es->p = p; /* initialize LwIP tcp_sent callback function */ tcp_sent(tpcb, tcp_echoserver_sent); printf("设备刚连接，挂载刚才接收到的数据，设置发送完成回调 \r\n"); /* send back the received data (echo) */ tcp_echoserver_send(tpcb, es); ret_err = ERR_OK; } else if (es->state == ES_RECEIVED) { /* more data received from client and previous data has been already sent*/ if(es->p == NULL) { es->p = p; printf("接收到的数据直接回传 \r\n"); /* send back received data */ tcp_echoserver_send(tpcb, es); } else { struct pbuf *ptr; printf("上次的数据还未发送完成，把新数据拼接在后面 \r\n"); /* chain pbufs to the end of what we recv'ed previously */ ptr = es->p; pbuf_chain(ptr,p); } ret_err = ERR_OK; } else if(es->state == ES_CLOSING) { printf("当前已经是关闭连接了，但还是受到数据 \r\n"); /* odd case, remote side closing twice, trash data */ tcp_recved(tpcb, p->tot_len); es->p = NULL; pbuf_free(p); ret_err = ERR_OK; } else { /* unkown es->state, trash data */ tcp_recved(tpcb, p->tot_len); es->p = NULL; pbuf_free(p); ret_err = ERR_OK; } return ret_err; } /** * @brief This function implements the tcp_err callback function (called * when a fatal tcp_connection error occurs. * @param arg: pointer on argument parameter * @param err: not used * @retval None */ static void tcp_echoserver_error(void *arg, err_t err) { struct tcp_echoserver_struct *es; LWIP_UNUSED_ARG(err); printf("错误 ： %d \r\n",err); es = (struct tcp_echoserver_struct *)arg; if (es != NULL) { /* free es structure */ mem_free(es); } } /** * @brief This function implements the tcp_poll LwIP callback function * @param arg: pointer on argument passed to callback * @param tpcb: pointer on the tcp_pcb for the current tcp connection * @retval err_t: error code */ static err_t tcp_echoserver_poll(void *arg, struct tcp_pcb *tpcb) { err_t ret_err; struct tcp_echoserver_struct *es; es = (struct tcp_echoserver_struct *)arg; if (es != NULL) { if (es->p != NULL) { tcp_sent(tpcb, tcp_echoserver_sent); /* there is a remaining pbuf (chain) , try to send data */ tcp_echoserver_send(tpcb, es); } else { /* no remaining pbuf (chain) */ if(es->state == ES_CLOSING) { /* close tcp connection */ tcp_echoserver_connection_close(tpcb, es); } } ret_err = ERR_OK; } else { /* nothing to be done */ tcp_abort(tpcb); ret_err = ERR_ABRT; } return ret_err; } /** * @brief This function implements the tcp_sent LwIP callback (called when ACK * is received from remote host for sent data) * @param None * @retval None */ static err_t tcp_echoserver_sent(void *arg, struct tcp_pcb *tpcb, u16_t len) { struct tcp_echoserver_struct *es; LWIP_UNUSED_ARG(len); es = (struct tcp_echoserver_struct *)arg; es->retries = 0; if(es->p != NULL) { /* still got pbufs to send */ tcp_sent(tpcb, tcp_echoserver_sent); tcp_echoserver_send(tpcb, es); } else { /* if no more data to send and client closed connection*/ if(es->state == ES_CLOSING) tcp_echoserver_connection_close(tpcb, es); } return ERR_OK; } /** * @brief This function is used to send data for tcp connection * @param tpcb: pointer on the tcp_pcb connection * @param es: pointer on echo_state structure * @retval None */ static void tcp_echoserver_send(struct tcp_pcb *tpcb, struct tcp_echoserver_struct *es) { struct pbuf *ptr; err_t wr_err = ERR_OK; uint16_t Count ; printf("发送数据的总长度 : %ld \r\n",es->p->tot_len); printf("发送数据： \r\n"); while ((wr_err == ERR_OK) && (es->p != NULL) && (es->p->len <= tcp_sndbuf(tpcb))) { /* get pointer on pbuf from es structure */ ptr = es->p; //得到当前需要发送的数据缓存 pbuf for( Count =0 ; Count < ptr->len; Count++ ) { printf("0X%02X ",((uint8_t *)ptr->payload)[Count]); } /* enqueue data for transmission */ wr_err = tcp_write(tpcb, ptr->payload, ptr->len, TCP_WRITE_FLAG_COPY); //发送 if (wr_err == ERR_OK) { u16_t plen; u8_t freed; plen = ptr->len; //得到当前节点的数据长度 /* continue with next pbuf in chain (if any) */ es->p = ptr->next; //得到链表的下一个节点 if(es->p != NULL) //如果节点不为空 { /* increment reference count for es->p */ pbuf_ref(es->p); //成员 ref 的值加1 当收到数据时，pbuf成员ref的值为1 ，在pbuf_free（）函数中是对成员ref减一 如果结果为0则释放此节点内存并进入下一个节点 否则只是把成员ref的值减一 } /* chop first pbuf from chain */ do { /* try hard to free pbuf */ freed = pbuf_free(ptr); //每执行一个 pbuf中的成员ref的值减一 当它这个节点没有释放时，返回一直为0 } while(freed == 0); //执行直到释放这个节点内存为止 pbuf_free（）函数的返回值表示释放的内存的节点数 /* we can read more data now */ tcp_recved(tpcb, plen); //增加可以接收数据的大小 } else if(wr_err == ERR_MEM) { /* we are low on memory, try later / harder, defer to poll */ es->p = ptr; //重发 } else { /* other problem ?? */ } } printf("\r\n"); } /** * @brief This functions closes the tcp connection * @param tcp_pcb: pointer on the tcp connection * @param es: pointer on echo_state structure * @retval None */ static void tcp_echoserver_connection_close(struct tcp_pcb *tpcb, struct tcp_echoserver_struct *es) { /* remove all callbacks */ tcp_arg(tpcb, NULL); tcp_sent(tpcb, NULL); tcp_recv(tpcb, NULL); tcp_err(tpcb, NULL); tcp_poll(tpcb, NULL, 0); /* delete es structure */ if (es != NULL) { mem_free(es); } /* close tcp connection */ tcp_close(tpcb); printf("已关闭连接 \r\n"); } #endif /* LWIP_TCP */
https://www.stmcu.org.cn/module/forum/thread-612677-1-1.html
这个代码也是从官方的 TCP echoserver 例子COPY出来的，不过里面加入了串口输出信息，及一些注释，感觉写的很好的，就没怎么改了
。
看起来代码很多，起始真的不复杂，听了之前的以太网配置，这个理解起来还是很简单的。大致流程如下，先新建一个TCB_PCB、开始监听、挂载客户端连接请求回调函数、挂载接收数据回调函数、挂载发送完成回调函数、挂载出错回调函数、挂载心跳包回调函数、关闭连接等，最重要的是释放内存！每收到一个数据链，它已经被申请了内存，所有在处理完这个数据后一定要释放。
