我正在制作一个C ++套接字应用程序。
它与android设备连接。
在接收数据期间关闭手机连接时..
Framebuffer Ready
[PCast] Waiting for connection
[PCast] Connected
....
[PCast] Data arrived
[PCast] *** Downloading mode ***
[PCast] Downloading file. Please wait...
[PCast:sock2file] Downloading...
[PCast:sock2file] Disconnection detected. Exiting sock2file.
[PCast] Disconnected
(Close client socket descriptor)
[PCast] Waiting for connection
看起来连接已成功关闭。但当我重新启动服务器..
Framebuffer Ready
[PCast] Socket bind failed: Address already in use
当我的Android应用程序尝试连接时（服务器未运行），它表示它已连接到服务器。（数据传输不起作用）
当我跑步时
netstat -anp
我可以看到我的端口处于CLOSE_WAIT状态。
...
tcp 1 0 172.30.1.3:5520 172.30.1.2:47144 CLOSE_WAIT -
tcp 0 0 172.30.1.3:22 172.30.1.1:50598 ESTABLISHED -
tcp 1 0 172.30.1.3:5520 172.30.1.2:47202 CLOSE_WAIT -
...
代码（省略记录，韩国评论......）：
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <unistd.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>
#include <ctime>
#include <cmath>
#include <linux/fb.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <signal.h>
#include "imgs.h"
using std::string;
#define FBDEV "/dev/fb0"
int scrsize, width, height;
int basesize;
#define CMD_GET_IP_ETH "/home/pi/scripts/ip.sh eth"
#define CMD_GET_IP_WLN "/home/pi/scripts/ip.sh wlan"
#define getPercent(total, current) (current / total) * 100
#define getLargeValue(org, b) (org * b) / 320
short *display;
short org[320*240];
//Convert images to char map
char strmap[128][5*5];
bool debug = false;
void cons_log(string message){
printf("%s\n", message.c_str());
}
void drawPixel(int x, int y, short col){
if((width * y + x) < width * height){
display[width*y+x] = col;
}
}
short mkcolor(int r, int g, int b){
return ((r >> 3) << 11) | ((g >> 2) << 5) | (b >> 3);
}
void writeImage(int sx, int sy, char img[], int size){
size *= basesize;
for(int y = 0; y < 5; y++) for(int x = 0; x < 5; x++){
int prtx = sx + x * size, prty = sy + y * size;
for(int rx = 0; rx < size; rx++) for(int ry = 0; ry < size; ry++){
drawPixel(prtx + rx, prty + ry, img[5*y+x] * 0xffff);
}
}
}
void writeImage(char img[], int size){
int centerX = width / 2 - 5 * size / 2;
int centerY = height / 2 - 5 * size / 2;
writeImage(centerX, centerY, img, size);
}
void writeMessage(int x, int y, string s, int size){
size *= basesize;
y += height / 2 - size * 5;
for(int i = 0; i < s.length(); i++){
int prtx = x + i * (size * 5);
writeImage(prtx, y, strmap[s.at(i)], size / basesize);
}
}
void writeMessage(int y, string s, int size){
size *= basesize;
int x = width / 2 - ((s.length()) * (size * 5)) / 2;
y += height / 2 - size * 5;
for(int i = 0; i < s.length(); i++){
int prtx = x + i * (size * 5);
writeImage(prtx, y, strmap[s.at(i)], size / basesize);
}
}
void writeMessage(string s, int size){
writeMessage(0, s, size);
}
void clear(){
for(int i = 0; i < width * height; i++) display[i] = 0;
}
#define img_height(size) size * 5 * basesize
void printStandBy(bool connected){
clear();
writeMessage("pcast", 2);
char buffer[100];
FILE* pipe;
pipe = popen("sh /home/pi/scripts/ip.sh eth", "r");
fgets(buffer, 100, pipe);
pclose(pipe);
writeMessage(img_height(2) + 10, buffer, 1);
memset(buffer, 0, 100);
pipe = popen("sh /home/pi/scripts/ip.sh wlan", "r");
fgets(buffer, 100, pipe);
pclose(pipe);
writeMessage(img_height(2) * 2 + 10, buffer, 1);
if(connected){
writeMessage(img_height(2) * 3 + 10, "connected", 1);
}else{
writeMessage(img_height(2) * 3 + 10, "not connected", 1);
}
}
void printDownloading(){
clear();
writeImage(IMG_DOWNLOAD, 2);
writeMessage(img_height(2) + 10, "downloading", 1);
}
int server_sockfd, client_sockfd;
void endHandler(int signo){
if(client_sockfd != NULL) close(client_sockfd);
if(server_sockfd != NULL) close(server_sockfd);
exit(0);
}
bool sock2file(int socket){
system("sudo rm /tmp/tmp");
int count = 0;
int file = open("/tmp/tmp", O_WRONLY | O_CREAT, 0644);
int totalBytes = 0;
while(true){
char buffer[1024*1024];
int recvBytes = recv(socket, buffer, 1024*1024, MSG_DONTWAIT);
if(recvBytes == 0){
return false;
}else if(recvBytes == -1){
if(count == 5000){
char send[] = {1, NULL};
write(socket, send, 1);
break;
}else{
usleep(1000);
count++;
}
}else{
count = 0;
char send[] = {0, NULL};
write(socket, send, 1);
write(file, buffer, recvBytes);
totalBytes += recvBytes;
//byte to B/KB/MB/GB
int displaySize = totalBytes;
char sizeUnit = 'b';
if(displaySize > 1024){
displaySize /= 1024;
sizeUnit = 'k';
}
if(displaySize > 1024){
displaySize /= 1024;
sizeUnit = 'm';
}
//Print current status
char buf[100];
sprintf(buf, "received %d%c ", displaySize, sizeUnit);
string status(buf);
writeMessage(0, img_height(2) * 2 + 10, status, 1);
}
}
return true;
}
int main(int argc, char **argv){
if(argc == 2){
if(!strcmp(argv[0], "d")) debug = true;
}
signal(SIGTERM, endHandler);
signal(SIGINT, endHandler);
memcpy(strmap['0'], IMG_0, 5*5);
memcpy(strmap['1'], IMG_1, 5*5);
memcpy(strmap['2'], IMG_2, 5*5);
memcpy(strmap['3'], IMG_3, 5*5);
memcpy(strmap['4'], IMG_4, 5*5);
memcpy(strmap['5'], IMG_5, 5*5);
memcpy(strmap['6'], IMG_6, 5*5);
memcpy(strmap['7'], IMG_7, 5*5);
memcpy(strmap['8'], IMG_8, 5*5);
memcpy(strmap['9'], IMG_9, 5*5);
memcpy(strmap['.'], IMG_DOT, 5*5);
memcpy(strmap[':'], IMG_DOBULE_DOT, 5*5);
memcpy(strmap['a'], IMG_A, 5*5);
memcpy(strmap['b'], IMG_B, 5*5);
memcpy(strmap['c'], IMG_C, 5*5);
memcpy(strmap['d'], IMG_D, 5*5);
memcpy(strmap['e'], IMG_E, 5*5);
memcpy(strmap['f'], IMG_F, 5*5);
memcpy(strmap['g'], IMG_G, 5*5);
memcpy(strmap['h'], IMG_H, 5*5);
memcpy(strmap['i'], IMG_I, 5*5);
memcpy(strmap['j'], IMG_J, 5*5);
memcpy(strmap['k'], IMG_K, 5*5);
memcpy(strmap['m'], IMG_M, 5*5);
memcpy(strmap['n'], IMG_N, 5*5);
memcpy(strmap['l'], IMG_L, 5*5);
memcpy(strmap['o'], IMG_O, 5*5);
memcpy(strmap['p'], IMG_P, 5*5);
memcpy(strmap['q'], IMG_Q, 5*5);
memcpy(strmap['r'], IMG_R, 5*5);
memcpy(strmap['s'], IMG_S, 5*5);
memcpy(strmap['t'], IMG_T, 5*5);
memcpy(strmap['u'], IMG_U, 5*5);
memcpy(strmap['v'], IMG_V, 5*5);
memcpy(strmap['w'], IMG_W, 5*5);
memcpy(strmap['x'], IMG_X, 5*5);
memcpy(strmap['y'], IMG_Y, 5*5);
memcpy(strmap['z'], IMG_Z, 5*5);
memcpy(strmap[' '], IMG_SPACE, 5*5);
//Framebuffer Setup
int fb_fd;
fb_fd = open(FBDEV, O_RDWR);
if(!fb_fd){
exit(1);
}
fb_var_screeninfo fvsInfo;
if(ioctl(fb_fd, FBIOGET_VSCREENINFO, &fvsInfo)){
exit(1);
}
width = fvsInfo.xres;
height = fvsInfo.yres;
scrsize = width * height * 2;
basesize = (width + height) / 2 / 100;
display = (short *)mmap(0, scrsize, PROT_READ | PROT_WRITE, MAP_SHARED, fb_fd, 0);
if((int *)display == -1){
exit(1);
}
printStandBy(false);
//Socket setup
int state, client_len;
int pid;
struct sockaddr_in siClient, siServer;
state = 0;
client_len = sizeof(siClient);
if((server_sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0){
exit(0);
}
bzero(&siServer, sizeof(siServer));
siServer.sin_family = AF_INET;
siServer.sin_addr.s_addr = htonl(INADDR_ANY);
siServer.sin_port = htons(5520);
state = bind(server_sockfd , (struct sockaddr *)&siServer, sizeof(siServer));
if (state == -1){
exit(0);
}
state = listen(server_sockfd, 5);
if (state == -1){
exit(0);
}
while(1){
client_sockfd = accept(server_sockfd, (struct sockaddr *)&siClient,
&client_len);
if (client_sockfd == -1){
exit(0);
}
printStandBy(true);
int avg;
int orgtime = time(NULL);
while(1){
char datainfo[2];
int recvBytes = recv(client_sockfd, datainfo, 2, MSG_WAITALL);
if(recvBytes == 0 || recvBytes == -1) break;
else{
system("sudo killall omxplayer*");
write(client_sockfd, datainfo, 2);
//*** Downloading mode ***
printDownloading();
bool status = sock2file(client_sockfd);
if(!status) break;
printStandBy(true);
system("nohup omxplayer /tmp/tmp &");
}
}
printStandBy(false);
close(client_sockfd);
}
}
程序没有崩溃。我用Ctrl + C退出（正如你所看到的，有一个Ctrl + C处理程序，杀死信号......）
我的Android应用程序会在应用程序退出时关闭连接。
抱歉英文不好。
答案 0 :(得分：4)
当远程端异常关闭连接时，端口被绑定在TIME_WAIT状态，除非超时已到期，否则不能重用（即重新绑定）它。您可以减少超时，设置套接字选项SO_REUSEADDR以强制重用端口，或者等到重新启动服务器时释放端口。
答案 1 :(得分：1)
在侦听套接字上设置SO_REUSEADDR选项将强制操作系统允许您绑定到端口，即使它正在使用中。这将解决您的症状，但不会解决根本原因，因此如果确实有多台服务器在运行，则容易出现问题。
如果服务器在FIN从客户端到达之前在TCP套接字上发起FIN，则TCP状态机要求它转换到TIME_WAIT状态。在您的情况下，您可能在客户端实际关闭连接之前使用 Ctrl C 关闭服务器，因此服务器正在启动FIN。
由于您强行关闭服务器，因此您可能宁愿在TCP套接字上发出RESET。在大多数TCP堆栈上，通过启用SO_LINGER选项并使用超时值0来完成此操作。您还可以在等待客户端发送内容超时的情况下设置此项。