我正在学习如何编写服务器TCP套接字,其中客户端可以连接并等待命令......
fd = open("/tmp/myFIFO", O_RDWR);
if(fd<0){
perror("open() error");
exit(1);
}
do {
while ((nbytes = read(fd, buffer, sizeof(buffer)-1)) > 0) {
buffer[nbytes] = '\0';
printf("%s\n", buffer);
}
err = recv(cFD, strbuf, sizeof(strbuf), 0);
if (err < 0) {
if (errno != EWOULDBLOCK) {
perror(" recv() failed");
state = TRUE;
}
break;
}
if (err == 0) {
printf(" Connection closed\n");
state = TRUE;
break;
}
dSize = err;
printf(" %d bytes received\n", dSize);
err = send(cFD, buffer, strlen(buffer), 0);
if (err < 0) {
perror(" send() failed");
state = TRUE;
break;
}
} while (TRUE);
我只是得到了我遇到问题的代码部分。我正在读一根烟斗。我正在使用它向客户端发送消息..但我的问题是recv。在将从我的管道读取的数据发送到客户端之前,它等待客户端发送的数据。我想要发生的是每次我发送数据到我的管道它直接到客户端而不等待recv ..如何做到这一点?
这是完整的代码:
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <errno.h>
#include <string.h>
#include <sys/select.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <pthread.h>
#define TRUE 1
#define FALSE 0
typedef struct SERVER_FD{
int sPort;
int serverFD;
int smaxFD;
int newFD;
}sSD;
int cFD,
dSize,
err,
start = 1,
state,
DescRead,
DCSERVER = FALSE;
struct sockaddr_in addr, cli_addr;
unsigned long ip;
char strbuf[256];
socklen_t clilen;
fd_set fdin, fduse;
pid_t pid, sid;
int fd=-1;
int nbytes;
char buffer[256];
void process(int ServerFD, int Port, int sMax, int NewSFD);
void cleanUP(int i, int max);
void dlogs(unsigned long ip);
void daemonize();
main (int argc, char *argv[])
{
sSD link;
sSD *sCon;
sCon = &link;
sCon->sPort = 53234;
fd = open("/tmp/myFIFO", O_RDWR);
if(fd<0){
perror("open() error");
exit(1);
}
printf("Starting Server-G\n");
fcntl(fd, F_SETFL,
fcntl(fd, F_GETFL) | O_NONBLOCK);
sCon->serverFD = socket(AF_INET, SOCK_STREAM, 0);
if (sCon->serverFD != -1) {
err = setsockopt(sCon->serverFD, SOL_SOCKET, SO_REUSEADDR,(char *)&start, sizeof(start));
if (err != -1) {
err = ioctl(sCon->serverFD, FIONBIO, (char *)&start);
if (err != -1){
process(sCon->serverFD,sCon->sPort,sCon->smaxFD,sCon->newFD);
}
else{
perror("ioctl() failed");
close(sCon->serverFD);
exit(EXIT_FAILURE);
}
}
else{
perror("setsockopt() failed");
close(sCon->serverFD);
exit(EXIT_FAILURE);
}
}
else{
perror("FAILED CONNECTING TO SOCKET");
exit(EXIT_FAILURE);
}
}
void process(int ServerFD, int Port, int sMax, int NewSFD){
bzero((char *) &addr, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = 0;
addr.sin_port = htons(Port);
err = bind(ServerFD,(struct sockaddr *)&addr, sizeof(addr));
if (err < 0) {
perror("bind() failed");
close(ServerFD);
exit(EXIT_FAILURE);
}
daemonize();
err = listen(ServerFD, 32);
if (err < 0) {
perror("listen() failed");
close(ServerFD);
exit(EXIT_FAILURE);
}
clilen = sizeof(cli_addr);
FD_ZERO(&fdin);
sMax = ServerFD;
FD_SET(ServerFD, &fdin);
do {
fduse = fdin;
err = select(sMax + 1, &fduse, NULL, NULL, NULL);
if (err < 0) {
perror(" select() failed");
break;
}
DescRead = err;
for (cFD=0; cFD <= sMax && DescRead > 0; ++cFD) {
if (FD_ISSET(cFD, &fduse)) {
DescRead -= 1;
if (cFD == ServerFD) {
do {
NewSFD = accept(ServerFD,(struct sockaddr *) &cli_addr, &clilen);
if (NewSFD < 0) {
if (errno != EWOULDBLOCK) {
perror(" accept() failed");
DCSERVER = TRUE;
}
break;
}
ip = ntohl(cli_addr.sin_addr.s_addr);
printf(" Connection from %d.%d.%d.%d\n",
(int)(ip>>24)&0xff,
(int)(ip>>16)&0xff,
(int)(ip>>8)&0xff,
(int)(ip>>0)&0xff);
dlogs(ip);
FD_SET(NewSFD, &fdin);
if (NewSFD > sMax)
sMax = NewSFD;
} while (NewSFD != -1);
}
else {
state = FALSE;
do {
//PART WHERE I'm Having problems.
err = recv(cFD, strbuf, sizeof(strbuf), 0);
if (err < 0) {
if (errno != EWOULDBLOCK) {
perror(" recv() failed");
state = TRUE;
}
break;
}
if (err == 0) {
printf(" Connection closed\n");
state = TRUE;
break;
}
dSize = err;
printf(" %d bytes received\n", dSize);
while ((nbytes = read(fd, buffer, sizeof(buffer)-1)) > 0) {
buffer[nbytes] = '\0';
printf("%s\n", buffer);
}
err = send(cFD, buffer, strlen(buffer), 0);
if (err < 0) {
perror(" send() failed");
state = TRUE;
break;
}
} while (TRUE);
if (state) {
close(fd);
close(cFD);
FD_CLR(cFD, &fdin);
if (cFD == sMax) {
while (FD_ISSET(sMax, &fdin) == FALSE)
sMax -= 1;
}
}
}
}
}
} while (DCSERVER == FALSE);
cleanUP(cFD, sMax);
}
void cleanUP(int i, int max){
for (i=0; i <= max; ++i) {
if (FD_ISSET(i, &fdin))
close(i);
}
}
void dlogs(unsigned long ip){
FILE* pFile = fopen("/sockF.txt", "a+");
fprintf(pFile,"Connection from: %d.%d.%d.%d",
(int)(ip>>24)&0xff,
(int)(ip>>16)&0xff,
(int)(ip>>8)&0xff,
(int)(ip>>0)&0xff);
fclose(pFile);
}
void daemonize(){
pid = fork();
if(pid<0){
perror("fork() failed");
exit(EXIT_FAILURE);
}
if(pid>0){
exit(EXIT_SUCCESS);
}
umask(0);
sid = setsid();
if(sid<0){
perror("setsid() failed");
exit(EXIT_FAILURE);
}
if((chdir("/")) < 0){
perror("failed changing directory");
exit(EXIT_FAILURE);
}
}
示例输出:我使用telnet和putty来测试服务器
From Telnet: IP: 192.168.5.53
Telnet 192.168.5.55 53234
./socks
Starting Server-G
Connection from: 192.168.5.53
现在当连接telnet时,我使用putty将数据发送到管道,以便服务器读取它。
From Putty:
echo "TEST" > /tmp/myFIFO
这里的问题是,无论何时我将数据从putty写入管道发送到服务器,服务器都会等待telnet发送数据,然后输出并发送我写入管道的数据。如何在同一个tym上进行recv和read工作,这样当我写入我的管道时,它会在不等待recv的情况下输出?
由于
编辑:我还使用线程来读取管道,但在服务器输出已经读取到管道的内容之前,它仍然等待recv()。
答案 0 :(得分:4)
使用select
或poll
等待两个文件句柄上的事件,例如。 (使用poll
)
#include <poll.h>
//...
struct pollfd pfds[2];
int rc;
/* Wait for input on either one of the fds */
pfds[0].fd = fd;
pfds[0].events = POLLIN;
pfds[1].fd = cFD;
pfds[1].events = POLLIN;
do {
/* Wait forever for something to happen */
rc = poll(&pfds, 2, -1);
/* Error handling elided */
if (pfds[0].revents & POLLIN)
{
/* Read from fd, change pfds[1].events to (POLLIN | POLLOUT) so you know when you
can write without blocking. also clear pfds[0].events so we don't read until we
write */
pfds[0].events = 0;
pfds[1].events = POLLIN | POLLOUT;
}
if (pfds[1].revents & POLLIN)
{
/* Read from socket */
}
if (pfds[1].revents & POLLOUT)
{
/* write to socket, reset events flags */
pfds[0].events = POLLIN;
pfds[1].events = POLLIN;
}
} while (1)