{"id":123681,"date":"2026-11-08T01:40:46","date_gmt":"2026-11-07T17:40:46","guid":{"rendered":"https:\/\/www.wsisp.com\/helps\/123681.html"},"modified":"2026-11-08T01:40:46","modified_gmt":"2026-11-07T17:40:46","slug":"freertos-stm32-lwip-%e8%b6%85%e6%97%b6%e7%bd%91%e7%bb%9c-i-o-%e5%ae%8c%e6%95%b4%e7%a4%ba%e4%be%8b","status":"publish","type":"post","link":"https:\/\/www.wsisp.com\/helps\/123681.html","title":{"rendered":"FreeRTOS + STM32 + LwIP \u8d85\u65f6\u7f51\u7edc I\/O \u5b8c\u6574\u793a\u4f8b"},"content":{"rendered":"

\/* MD \/ \u5bcc\u6587\u672c\u4e2d\u7684 .toc\uff08\u542b\u535a\u5ba2\u56ed\u642c\u5bb6\u7b49\u5d4c\u5957\u7ed3\u6784\uff09\uff1b.toc-box \u5728\u4fa7\u680f\uff0c\u4e0d\u53d7\u5f71\u54cd *\/
\n #content_views .toc,
\n \/* \u7f16\u8f91\u5668\u5e38\u5728\u76ee\u5f55\u524d\u540e\u63d2\u5165\u7a7a p\uff08:empty \u4ecd\u5360 20px\uff09\uff0c\u4e00\u5e76\u53bb\u6389\u907f\u514d\u9876\u7a7a\u9699 *\/
\n #content_views.markdown_views > p:empty:has(+ .toc),
\n #content_views.markdown_views > .toc + p:empty,
\n \/* \u5bcc\u6587\u672c\u65e7\u7248\u76ee\u5f55\u6807\u8bb0 *\/
\n #content_views.htmledit_views #main-toc,
\n #content_views.htmledit_views #hr-toc,
\n #content_views.htmledit_views p[id*=\\”-toc\\”] {
\n display: none !important;
\n }
\n \/* \u76ee\u5f55\u53bb\u6389\u540e\uff0c\u7d27\u8ddf\u7684\u9996\u4e2a\u6807\u9898\u4e0d\u518d\u591a\u51fa\u4e00\u5757\u4e0a\u8fb9\u8ddd *\/
\n #content_views.markdown_views > .toc + h1,
\n #content_views.markdown_views > .toc + h2,
\n #content_views.markdown_views > .toc + h3,
\n #content_views.markdown_views > .toc + h4,
\n #content_views.markdown_views > .toc + p:empty + h1,
\n #content_views.markdown_views > .toc + p:empty + h2,
\n #content_views.markdown_views > .toc + p:empty + h3,
\n #content_views.markdown_views > .toc + p:empty + h4 {
\n margin-top: 0 !important;
\n }<\/p>\n

\u4e0b\u9762\u662f\u4e00\u4e2a\u5b8c\u6574\u7684\u3001\u53ef\u76f4\u63a5\u53c2\u8003\u79fb\u690d\u7684\u5b9e\u73b0\u3002\u6838\u5fc3\u601d\u8def：LwIP socket \u9ed8\u8ba4\u662f\u963b\u585e\u7684，\u914d\u5408\u00a0SO_RCVTIMEO\/SO_SNDTIMEO\u00a0\u6216\u975e\u963b\u585e +\u00a0select\/poll\u00a0\u5b9e\u73b0\u8d85\u65f6\u3002\u8fd9\u91cc\u7ed9\u51fa\u57fa\u4e8e\u00a0select()\u00a0\u7684\u53ef\u79fb\u690d\u65b9\u6848（LwIP \u652f\u6301\u00a0select），\u5e76\u5904\u7406\u00a0EINTR\u3001\u90e8\u5206\u6536\u53d1\u7b49\u8fb9\u754c\u3002<\/p>\n

\n

1. \u5934\u6587\u4ef6\u4e0e\u914d\u7f6e<\/h3>\n

\/* net_io_task.h *\/
\n#ifndef NET_IO_TASK_H
\n#define NET_IO_TASK_H<\/p>\n

#include "FreeRTOS.h"
\n#include "task.h"
\n#include "lwip\/sockets.h"
\n#include "lwip\/inet.h"
\n#include "lwip\/errno.h"<\/p>\n

\/* \u4efb\u52a1\u914d\u7f6e *\/
\n#define NET_TASK_STACK_SIZE (512 * 4) \/* \u5b57\u8282，\u89c6 LwIP \u914d\u7f6e\u653e\u5927 *\/
\n#define NET_TASK_PRIO (tskIDLE_PRIORITY + 3)
\n#define NET_SERVER_PORT 8080
\n#define NET_CONNECT_TIMEOUT_MS 5000
\n#define NET_RECV_TIMEOUT_MS 3000
\n#define NET_SEND_TIMEOUT_MS 3000
\n#define NET_RECV_BUF_LEN 512<\/p>\n

void net_io_task(void *arg);<\/p>\n

#endif<\/p>\n

\n

2. \u6838\u5fc3\u5de5\u5177\u51fd\u6570：\u5e26\u8d85\u65f6\u7684 send \/ recv<\/h3>\n

\/* net_io_util.c *\/
\n#include "net_io_task.h"
\n#include <string.h><\/p>\n

\/* \u8fd4\u56de >=0: \u5b9e\u9645\u53d1\u9001\u5b57\u8282\u6570; -1: \u9519\u8bef(\u542b\u8d85\u65f6) *\/
\nstatic int sock_send_timeout(int s, const void *buf, size_t len, uint32_t timeout_ms)
\n{
\n const uint8_t *p = (const uint8_t *)buf;
\n size_t sent = 0;
\n uint32_t start = xTaskGetTickCount();<\/p>\n

while (sent < len) {
\n fd_set wfds;
\n FD_ZERO(&wfds);
\n FD_SET(s, &wfds);<\/p>\n

\/* \u8ba1\u7b97\u5269\u4f59\u65f6\u95f4 *\/
\n uint32_t elapsed = (xTaskGetTickCount() – start) * portTICK_PERIOD_MS;
\n if (elapsed >= timeout_ms) {
\n errno = EWOULDBLOCK;
\n return -1;
\n }
\n struct timeval tv;
\n uint32_t remain_ms = timeout_ms – elapsed;
\n tv.tv_sec = remain_ms \/ 1000;
\n tv.tv_usec = (remain_ms % 1000) * 1000;<\/p>\n

int rc = lwip_select(s + 1, NULL, &wfds, NULL, &tv);
\n if (rc < 0) {
\n if (errno == EINTR) continue; \/* \u88ab\u4fe1\u53f7\/\u5176\u5b83\u4e2d\u65ad\u6253\u65ad，\u91cd\u8bd5 *\/
\n return -1;
\n }
\n if (rc == 0) { \/* \u8d85\u65f6 *\/
\n errno = EWOULDBLOCK;
\n return -1;
\n }<\/p>\n

ssize_t n = lwip_send(s, p + sent, len – sent, 0 \/* \u6216 MSG_DONTWAIT *\/);
\n if (n < 0) {
\n if (errno == EINTR) continue;
\n if (errno == EWOULDBLOCK || errno == EAGAIN) continue; \/* \u518d\u7b49 *\/
\n return -1;
\n }
\n sent += (size_t)n;
\n }
\n return (int)sent;
\n}<\/p>\n

\/* \u8fd4\u56de >0: \u6536\u5230\u5b57\u8282\u6570; 0: \u5bf9\u7aef\u5173\u95ed; -1: \u9519\u8bef(\u542b\u8d85\u65f6) *\/
\nstatic int sock_recv_timeout(int s, void *buf, size_t len, uint32_t timeout_ms)
\n{
\n uint32_t start = xTaskGetTickCount();<\/p>\n

for (;;) {
\n fd_set rfds;
\n FD_ZERO(&rfds);
\n FD_SET(s, &rfds);<\/p>\n

uint32_t elapsed = (xTaskGetTickCount() – start) * portTICK_PERIOD_MS;
\n if (elapsed >= timeout_ms) { errno = EWOULDBLOCK; return -1; }<\/p>\n

struct timeval tv;
\n uint32_t remain_ms = timeout_ms – elapsed;
\n tv.tv_sec = remain_ms \/ 1000;
\n tv.tv_usec = (remain_ms % 1000) * 1000;<\/p>\n

int rc = lwip_select(s + 1, &rfds, NULL, NULL, &tv);
\n if (rc < 0) {
\n if (errno == EINTR) continue;
\n return -1;
\n }
\n if (rc == 0) { errno = EWOULDBLOCK; return -1; }<\/p>\n

ssize_t n = lwip_recv(s, buf, len, 0);
\n if (n < 0) {
\n if (errno == EINTR || errno == EWOULDBLOCK || errno == EAGAIN)
\n continue;
\n return -1;
\n }
\n return (int)n; \/* n==0 \u8868\u793a\u5bf9\u7aef\u5173\u95ed *\/
\n }
\n}<\/p>\n

\u4e3a\u4ec0\u4e48\u8981\u7528\u00a0select\u00a0\u800c\u4e0d\u662f\u5355\u7eaf\u00a0SO_RCVTIMEO？
\nLwIP \u7684\u00a0SO_RCVTIMEO\/SO_SNDTIMEO\u00a0\u5728\u4e0d\u540c\u79fb\u690d\u7248\u672c\u91cc\u884c\u4e3a\u4e0d\u5b8c\u5168\u4e00\u81f4（\u90e8\u5206\u7248\u672c\u00a0setsockopt\u00a0\u540e\u4ec5\u5bf9\u540e\u7eed\u8c03\u7528\u751f\u6548\u3001\u4e14\u4e0d\u540c lwipopts \u4e0b\u652f\u6301\u4e0d\u540c）\u3002select\u00a0\u662f LwIP \u6807\u51c6\u652f\u6301\u3001\u884c\u4e3a\u6700\u7a33\u7684\u8def\u5f84，\u4e14\u80fd\u540c\u65f6\u7edf\u4e00\u7ba1\u7406\u6536\u53d1\u8d85\u65f6\u3002\u82e5\u4f60\u7684 LwIP \u7248\u672c\u00a0SO_RCVTIMEO\u00a0\u5b8c\u6574\u53ef\u7528，\u4e5f\u53ef\u7528，\u89c1\u6587\u672b\u8bf4\u660e\u3002<\/p>\n

\n

3. \u5e26\u8d85\u65f6\u7684 connect<\/h3>\n

\/* \u8fd4\u56de 0 \u6210\u529f, -1 \u5931\u8d25\/\u8d85\u65f6 *\/
\nstatic int sock_connect_timeout(const char *ip, uint16_t port, uint32_t timeout_ms)
\n{
\n int s = lwip_socket(AF_INET, SOCK_STREAM, 0);
\n if (s < 0) return -1;<\/p>\n

\/* \u5148\u8bbe\u4e3a\u975e\u963b\u585e\u4ee5\u652f\u6301 connect \u8d85\u65f6 *\/
\n int flags = lwip_fcntl(s, F_GETFL, 0);
\n lwip_fcntl(s, F_SETFL, flags | O_NONBLOCK);<\/p>\n

struct sockaddr_in addr;
\n memset(&addr, 0, sizeof(addr));
\n addr.sin_family = AF_INET;
\n addr.sin_port = htons(port);
\n addr.sin_addr.s_addr = inet_addr(ip);<\/p>\n

int rc = lwip_connect(s, (struct sockaddr *)&addr, sizeof(addr));
\n if (rc < 0 && errno != EINPROGRESS) {
\n lwip_close(s);
\n return -1;
\n }<\/p>\n

if (rc < 0) { \/* EINPROGRESS: \u7b49\u5f85\u53ef\u5199 *\/
\n fd_set wfds, efds;
\n FD_ZERO(&wfds); FD_ZERO(&efds);
\n FD_SET(s, &wfds); FD_SET(s, &efds);<\/p>\n

struct timeval tv;
\n tv.tv_sec = timeout_ms \/ 1000;
\n tv.tv_usec = (timeout_ms % 1000) * 1000;<\/p>\n

rc = lwip_select(s + 1, NULL, &wfds, &efds, &tv);
\n if (rc <= 0) { \/* \u8d85\u65f6\u6216\u9519\u8bef *\/
\n lwip_close(s);
\n return -1;
\n }
\n \/* \u68c0\u67e5 connect \u662f\u5426\u771f\u7684\u6210\u529f *\/
\n int soerr = 0;
\n socklen_t slen = sizeof(soerr);
\n lwip_getsockopt(s, SOL_SOCKET, SO_ERROR, &soerr, &slen);
\n if (soerr != 0) {
\n lwip_close(s);
\n return -1;
\n }
\n }<\/p>\n

\/* \u6062\u590d\u963b\u585e\u6a21\u5f0f，\u4fbf\u4e8e\u540e\u7eed recv\/send \u8bed\u4e49\u6e05\u6670 *\/
\n lwip_fcntl(s, F_SETFL, flags);
\n return s;
\n}<\/p>\n

\n

4. \u5b8c\u6574\u4efb\u52a1\u793a\u4f8b<\/h3>\n

\/* net_io_task.c *\/
\n#include "net_io_task.h"
\n#include <string.h>
\n#include <stdio.h><\/p>\n

static const char *kServerIP = "192.168.1.100";<\/p>\n

void net_io_task(void *arg)
\n{
\n (void)arg;
\n uint8_t rxbuf[NET_RECV_BUF_LEN];<\/p>\n

for (;;) {
\n \/* —- 1. \u5efa\u8fde（\u5e26\u8d85\u65f6） —- *\/
\n int s = sock_connect_timeout(kServerIP, NET_SERVER_PORT, NET_CONNECT_TIMEOUT_MS);
\n if (s < 0) {
\n printf("[NET] connect failed\/timeout, retry in 2s\\\\r\\\\n");
\n vTaskDelay(pdMS_TO_TICKS(2000));
\n continue;
\n }
\n printf("[NET] connected\\\\r\\\\n");<\/p>\n

\/* —- 2. \u53d1\u9001\u8bf7\u6c42（\u5e26\u8d85\u65f6） —- *\/
\n const char *req = "GET \/status HTTP\/1.0\\\\r\\\\nHost: dev\\\\r\\\\n\\\\r\\\\n";
\n if (sock_send_timeout(s, req, strlen(req), NET_SEND_TIMEOUT_MS) < 0) {
\n printf("[NET] send timeout\/err, close\\\\r\\\\n");
\n lwip_close(s);
\n vTaskDelay(pdMS_TO_TICKS(1000));
\n continue;
\n }<\/p>\n

\/* —- 3. \u63a5\u6536\u54cd\u5e94（\u5e26\u8d85\u65f6，\u5faa\u73af\u6536\u76f4\u5230\u5bf9\u7aef\u5173\u95ed\u6216\u8d85\u65f6） —- *\/
\n int total = 0;
\n for (;;) {
\n int n = sock_recv_timeout(s, rxbuf, sizeof(rxbuf), NET_RECV_TIMEOUT_MS);
\n if (n > 0) {
\n \/* \u5904\u7406\u6570\u636e：\u6b64\u5904\u4ec5\u6253\u5370\u957f\u5ea6，\u5b9e\u9645\u53ef\u89e3\u6790\/\u5165\u961f *\/
\n total += n;
\n \/* fwrite \/ \u89e3\u6790 … *\/
\n } else if (n == 0) {
\n printf("[NET] peer closed, total=%d\\\\r\\\\n", total);
\n break; \/* \u5bf9\u7aef\u5173\u95ed，\u6b63\u5e38\u7ed3\u675f *\/
\n } else {
\n if (errno == EWOULDBLOCK)
\n printf("[NET] recv timeout, total=%d\\\\r\\\\n", total);
\n else
\n printf("[NET] recv error\\\\r\\\\n");
\n break; \/* \u8d85\u65f6\u6216\u9519\u8bef，\u7ed3\u675f\u672c\u6b21\u4f1a\u8bdd *\/
\n }
\n }<\/p>\n

\/* —- 4. \u5173\u95ed\u5e76\u5ef6\u65f6\u91cd\u8fde —- *\/
\n lwip_close(s);
\n vTaskDelay(pdMS_TO_TICKS(3000));
\n }
\n}<\/p>\n

\n

5. \u521b\u5efa\u4efb\u52a1（main \u6216\u521d\u59cb\u5316\u5904）<\/h3>\n

#include "net_io_task.h"<\/p>\n

void app_start(void)
\n{
\n \/* \u524d\u7f6e：\u7f51\u5361\u5df2 up，DHCP \u5b8c\u6210\u6216\u9759\u6001 IP \u5df2\u8bbe\u7f6e，LwIP \u5df2\u521d\u59cb\u5316 *\/
\n xTaskCreate(net_io_task,
\n "net_io",
\n NET_TASK_STACK_SIZE \/ sizeof(StackType_t), \/* FreeRTOS \u7528 word *\/
\n NULL,
\n NET_TASK_PRIO,
\n NULL);
\n}<\/p>\n

\u6ce8\u610f：xTaskCreate\u00a0\u7684\u6808\u5927\u5c0f\u5728\u591a\u6570 FreeRTOS \u79fb\u690d\u91cc\u4ee5\u00a0word（4 \u5b57\u8282）\u00a0\u4e3a\u5355\u4f4d；\u4e0a\u9762\u00a0NET_TASK_STACK_SIZE\u00a0\u6211\u6309\u5b57\u8282\u7ed9\u4e86\u5b8f，\u521b\u5efa\u65f6\u9664\u4ee5\u00a0sizeof(StackType_t)\u3002\u82e5\u4f60\u76f4\u63a5\u4e60\u60ef\u7528 word \u6570，\u628a\u5b8f\u6539\u6210 word \u6570\u5e76\u53bb\u6389\u9664\u6cd5\u5373\u53ef\u3002<\/p>\n

\n

6.\u00a0lwipopts.h\u00a0\u5173\u952e\u914d\u7f6e<\/h3>\n

\/* lwipopts.h \u7247\u6bb5 \u2014\u2014 \u5fc5\u987b\u786e\u4fdd select \u4e0e socket \u76f8\u5173\u5f00\u542f *\/
\n#define LWIP_SOCKET 1
\n#define LWIP_NETCONN 1
\n#define LWIP_SO_RCVTIMEO 1 \/* \u82e5\u60f3\u7528 SO_RCVTIMEO \u65b9\u5f0f *\/
\n#define LWIP_SO_SNDTIMEO 1
\n#define LWIP_SO_RCVBUF 1
\n#define LWIP_SELECT 1 \/* LwIP 1.4+ \u5185\u90e8\u7531 LWIP_SOCKET \u63d0\u4f9b *\/<\/p>\n

#define MEMP_NUM_NETCONN 8 \/* \u6bcf socket \u5360\u4e00\u4e2a netconn *\/
\n#define MEMP_NUM_NETBUF 16
\n#define MEMP_NUM_TCP_SEG 32
\n#define TCP_SND_BUF (4 * TCP_MSS)
\n#define TCP_WND (4 * TCP_MSS)<\/p>\n

\/* \u82e5\u7528 select，\u786e\u4fdd\u4ee5\u4e0b\u5f00\u542f（\u90e8\u5206\u7248\u672c） *\/
\n#define LWIP_TIMEVAL_PRIVATE 0 \/* \u7528\u7cfb\u7edf\u7684 struct timeval，\u6216 1 \u7528 LwIP \u81ea\u5e26 *\/<\/p>\n

\n

7. \u8fb9\u754c\u4e0e\u5e38\u89c1\u5751（\u52a1\u5fc5\u770b）<\/h3>\n\n\u573a\u666f\u5904\u7406<\/tr>\n\n\n\n\n\n\n\n\n\n\n
select\u00a0\u8fd4\u56de\u503c<\/td>\n0=\u8d85\u65f6，>0=\u5c31\u7eea\u6570，<0=\u9519\u8bef\u3002\u8d85\u65f6\u8981\u663e\u5f0f\u5224\u5b9a，\u4e0d\u80fd\u5f53\u9519\u8bef\u4e00\u5f8b\u5173\u95ed<\/td>\n<\/tr>\n
EINTR<\/td>\nFreeRTOS \u4e0b LwIP\u00a0select\u00a0\u4e00\u822c\u4e0d\u4f1a\u8fd4\u56de EINTR（\u65e0\u4fe1\u53f7\u673a\u5236），\u4f46\u4fdd\u7559\u91cd\u8bd5\u903b\u8f91\u65e0\u5bb3；EWOULDBLOCK\/EAGAIN\u00a0\u5fc5\u987b\u91cd\u8bd5\u800c\u975e\u76f4\u63a5\u5931\u8d25<\/td>\n<\/tr>\n
\u90e8\u5206\u6536\u53d1<\/td>\nTCP \u662f\u5b57\u8282\u6d41，send\u00a0\u53ef\u80fd\u53ea\u53d1\u4e00\u90e8\u5206\u3001recv\u00a0\u53ef\u80fd\u5c11\u4e8e\u8bf7\u6c42\u957f\u5ea6，\u5fc5\u987b\u7528\u5faa\u73af\u7d2f\u8ba1（\u4e0a\u9762\u5df2\u5904\u7406）<\/td>\n<\/tr>\n
recv\u00a0\u8fd4\u56de 0<\/td>\n\u8868\u793a\u5bf9\u7aef\u6709\u5e8f\u5173\u95ed，\u662f\u6b63\u5e38\u7ec8\u6b62，\u4e0d\u662f\u9519\u8bef<\/td>\n<\/tr>\n
connect \u8d85\u65f6<\/td>\n\u5fc5\u987b\u7528\u975e\u963b\u585e +\u00a0select\u00a0+\u00a0SO_ERROR\u00a0\u68c0\u67e5，\u5426\u5219\u00a0connect\u00a0\u53ef\u80fd\u957f\u65f6\u95f4\u963b\u585e\u4efb\u52a1<\/td>\n<\/tr>\n
\u4efb\u52a1\u4f18\u5148\u7ea7<\/td>\n\u7f51\u7edc\u4efb\u52a1\u4f18\u5148\u7ea7\u4e0d\u8981\u9ad8\u4e8e LwIP \u7684\u00a0tcpip_thread（\u901a\u5e38\u00a0LWIP_TCPIP_CORE_LOCKING\u00a0\u6216\u72ec\u7acb\u7ebf\u7a0b，\u4e00\u822c\u4e3a\u4e2d\u9ad8\u4f18\u5148\u7ea7）；\u8fc7\u4f4e\u53ef\u80fd\u997f\u6b7b<\/td>\n<\/tr>\n
\u6808\u5927\u5c0f<\/td>\nLwIP + \u5b57\u7b26\u4e32\u5904\u7406 + printf \u5f88\u5403\u6808，\u5efa\u8bae \u2265 2 KB，\u542b printf \u65f6\u66f4\u5927<\/td>\n<\/tr>\n
printf\u00a0\u963b\u585e<\/td>\n\u82e5\u5e95\u5c42 UART \u963b\u585e，\u957f\u65f6\u95f4\u6253\u5370\u4f1a\u5f71\u54cd\u8d85\u65f6\u7cbe\u5ea6；\u91cf\u4ea7\u5efa\u8bae\u7528 RTT\/\u961f\u5217<\/td>\n<\/tr>\n
\u8d85\u65f6\u7cbe\u5ea6<\/td>\n\u57fa\u4e8e\u00a0xTaskGetTickCount()，\u53d7\u00a0configTICK_RATE_HZ\u00a0\u9650\u5236；1 ms tick \u4e0b\u6beb\u79d2\u7ea7\u8db3\u591f，\u82e5\u8981\u6c42\u66f4\u7cbe\u786e\u7528\u00a0xTaskGetTickCountFromISR\/\u9ad8\u7cbe\u5ea6\u5b9a\u65f6\u5668<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\n

8. \u5907\u9009\u65b9\u6848：\u76f4\u63a5\u7528\u00a0SO_RCVTIMEO \/ SO_SNDTIMEO<\/h3>\n

\u82e5\u4f60\u7684 LwIP \u7248\u672c\u5b8c\u6574\u652f\u6301\u8fd9\u4e24\u4e2a\u9009\u9879（LWIP_SO_RCVTIMEO=1,\u00a0LWIP_SO_SNDTIMEO=1），\u4ee3\u7801\u53ef\u66f4\u77ed：<\/p>\n

struct timeval tv = { .tv_sec = NET_RECV_TIMEOUT_MS \/ 1000,
\n .tv_usec = (NET_RECV_TIMEOUT_MS % 1000) * 1000 };
\nlwip_setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));<\/p>\n

ssize_t n = lwip_recv(s, buf, len, 0);
\nif (n < 0 && (errno == EWOULDBLOCK || errno == EAGAIN)) {
\n \/* \u8d85\u65f6 *\/
\n}<\/p>\n

\u6743\u8861：SO_*TIMEO\u00a0\u7b80\u6d01，\u4f46\u90e8\u5206 LwIP \u79fb\u690d\u7248\u672c\u5bf9\u00a0send\u00a0\u8d85\u65f6\u4e0d\u652f\u6301\u6216\u8bed\u4e49\u4e0d\u4e00\u81f4；select\u00a0\u65b9\u6848\u8de8\u7248\u672c\u6700\u7a33，\u4e14\u80fd\u7edf\u4e00\u7ba1\u7406\u591a socket\u3002\u91cf\u4ea7\/\u591a\u8fde\u63a5\u5efa\u8bae\u7528\u00a0select\u00a0\u65b9\u6848\u3002<\/p>\n

\n

9. \u6d41\u7a0b\u603b\u7ed3<\/h3>\n

text<\/p>\n

connect(\u975e\u963b\u585e) \u2192 select \u7b49\u53ef\u5199(\u8d85\u65f6) \u2192 SO_ERROR \u6821\u9a8c
\n \u2502
\nsend(\u5faa\u73af) \u2192 select \u7b49\u53ef\u5199(\u6bcf\u8f6e\u91cd\u65b0\u7b97\u5269\u4f59\u8d85\u65f6) \u2192 \u7d2f\u8ba1\u5b57\u8282
\n \u2502
\nrecv(\u5faa\u73af) \u2192 select \u7b49\u53ef\u8bfb(\u8d85\u65f6) \u2192 n>0 \u5904\u7406 \/ n==0 \u5173\u95ed \/ n<0 \u8d85\u65f6\u6216\u9519\u8bef
\n \u2502
\nclose \u2192 \u5ef6\u65f6 \u2192 \u91cd\u8fde<\/p>\n

\u6574\u4e2a\u4efb\u52a1\u5185\u90e8\u6ca1\u6709\u4efb\u4f55\u65e0\u9650\u963b\u585e\u8c03\u7528，\u6bcf\u4e2a\u7f51\u7edc\u64cd\u4f5c\u90fd\u6709\u660e\u786e\u4e0a\u9650，\u6ee1\u8db3\u5b9e\u65f6\u7cfb\u7edf\u5bf9\u4efb\u52a1\u54cd\u5e94\u6027\u7684\u8981\u6c42\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"

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