0
我正在寫簡單的TCP服務器，並且發現了一些問題。也許你可以幫我一下。 所以，我先寫了一個echo服務器（用來測試與計算機客戶端的連接）。它工作正常，但現在我需要改變一下。服務器應該在每隔X秒/分鐘連接並向每個客戶端發送相同的字符[]時將char [100]發送到客戶端。Linux TCP服務器每隔X秒向少數客戶端發送RAW數據
我嘗試了許多更改，但應用程序只會崩潰。在這段代碼中評論了我的一些「錯誤」。
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <errno.h>
#include <unistd.h>
/* BufferLength is 100 bytes */
#define BufferLength 100
/* Server port */
#define SERVPORT 6000
int main(){
/* Variable and structure definitions. */
int sd, wyslij, sd2, rc, length = sizeof(int);
int totalcnt = 0, on = 1;
char temp;
char buffer[BufferLength];
struct sockaddr_in serveraddr;
struct sockaddr_in their_addr;
fd_set read_fd;
struct timeval timeout;
timeout.tv_sec = 15;
timeout.tv_usec = 0;
char datadata[100] = "This is a test string from server lol!!! ";
/* Get a socket descriptor */
if((sd = socket(AF_INET, SOCK_STREAM, 0)) < 0){
perror("Server-socket() error");
/* exit */
exit (-1);
}else
printf("Server-socket() is OK\n");
/* Allow socket descriptor to be reusable */
if((rc = setsockopt(sd, SOL_SOCKET, SO_REUSEADDR, (char *)&on, sizeof(on))) < 0){
perror("Server-setsockopt() error");
close(sd);
exit (-1);
}else
printf("Server-setsockopt() is OK\n");
/* bind to an address */
memset(&serveraddr, 0x00, sizeof(struct sockaddr_in));
serveraddr.sin_family = AF_INET;
serveraddr.sin_port = htons(SERVPORT);
serveraddr.sin_addr.s_addr = htonl(INADDR_ANY);
printf("Using %s, listening at %d\n", inet_ntoa(serveraddr.sin_addr), SERVPORT);
if((rc = bind(sd, (struct sockaddr *)&serveraddr, sizeof(serveraddr))) < 0){
perror("Server-bind() error");
/* Close the socket descriptor */
close(sd);
/* and just exit */
exit(-1);
}else
printf("Server-bind() is OK\n");
/* queue up to 10 clients */
if((rc = listen(sd, 10)) < 0){
perror("Server-listen() error");
close(sd);
exit (-1);
}else
printf("Server-Ready for client connection...\n");
/* accept() the incoming connection request. */
int sin_size = sizeof(struct sockaddr_in);
if((sd2 = accept(sd, (struct sockaddr *)&their_addr, &sin_size)) < 0){
perror("Server-accept() error");
close(sd);
exit (-1);
}else
printf("Server-accept() is OK\n");
/*client IP*/
printf("Server-new socket, sd2 is OK...\n");
printf("Got connection from the client: %s\n", inet_ntoa(their_addr.sin_addr));
/* Wait for up to 15 seconds on */
/* select() for data to be read. */
FD_ZERO(&read_fd);
FD_SET(sd2, &read_fd);
rc = select(sd2+1, &read_fd, NULL, NULL, &timeout);
/* rc = write(sd2, datadata, sizeof(datadata)); */
if((rc == 1) && (FD_ISSET(sd2, &read_fd))){
/* rc = write(sd2, datadata, sizeof(datadata)); */
/* Read data from the client. */
totalcnt = 0;
while(totalcnt < BufferLength){
/* read() from client */
rc = read(sd2, &buffer[totalcnt], (BufferLength - totalcnt));
if(rc < 0){
perror("Server-read() error");
close(sd);
close(sd2);
exit (-1);
}else if (rc == 0){
printf("Client program has issued a close()\n");
close(sd);
close(sd2);
exit(-1);
}
else{
totalcnt += rc;
printf("Server-read() is OK\n");
}
}
}else if (rc < 0){
perror("Server-select() error");
close(sd);
close(sd2);
exit(-1);
}
/* rc == 0 */
else{
printf("Server-select() timed out.\n");
close(sd);
close(sd2);
exit(-1);
}
/* Shows the data */
printf("Received data from the client: %s\n", buffer);
/* write() some bytes of string, */
/* back to the client. */
printf("Server-Echoing back to client...\n");
rc = write(sd2, datadata, sizeof(datadata));
if(rc != totalcnt){
perror("Server-write() error");
/* Get the error number. */
rc = getsockopt(sd2, SOL_SOCKET, SO_ERROR, &temp, &length);
if(rc == 0){
/* Print out the asynchronously */
/* received error. */
errno = temp;
perror("SO_ERROR was: ");
}else
printf("Server-write() is OK\n");
close(sd);
close(sd2);
exit(-1);
}
/* Close the connection to the client and */
/* close the server listening socket. */
close(sd2);
close(sd);
exit(0);
return 0;
}
非常感謝各位好友！
它在哪裏崩潰？你有沒有在gdb或其他調試器中運行它？ – Joe
首先，您應該學習如何使用調試器，例如[GNU調試器]（http://www.gnu.org/software/gdb/）。如果使用調試信息（'-g'標誌爲GCC/clang）編譯並在調試器中運行程序，那麼程序將在發生崩潰時停止。然後，您可以使用'bt'命令來顯示功能回溯，以瞭解您是如何在故障現場結束的。如果它不在你的某個函數中，可以使用'up'命令遍歷調用堆棧，直到你處於其中一個函數中。你可以使用'p variable'來打印變量的值。檢查例如'NULL'指針。 –
當我取消註釋行rc = write（sd2，datadata，sizeof（datadata））時崩潰;它有兩個地方在上面的代碼中註釋 – bluemuz