0
我一直在努力學習unix網絡編程，所以我試圖編寫一個客戶端/服務器程序，其中客戶端發送消息和服務器返回轉換爲大寫字母的郵件。unix tcp客戶端/服務器怪異行爲
當我運行服務器並將客戶端連接到我自己的機器併發送一些測試字符串時，它可以正常工作，直到我以前輸入的內容寫入屏幕。
我懷疑它與緩衝區有關。這裏的樣品運行後，我啓動服務器：
CAN @ Ubuntu的：〜$ CD桌面
CAN @ Ubuntu的：〜/桌面$ ./tcpuppcli 127.0.0.1
輸入字符串呼應：測試
回波響應：TEST
輸入字符串呼應：字符串2
回波響應：STRING2
輸入字符串呼應：STRING3
回波響應：STRING3
輸入字符串呼應：aaaaaaaaafsfagd
回波響應：AAAAAAAAAFSFAGD
輸入字符串呼應：gdsgsg
回聲響應：GDSGSG
AAFS FAGD ----------->！這是來自先前輸入的字符的奇怪行！
輸入字符串呼應：^ C
CAN @ Ubuntu的：〜/桌面$
服務器和客戶端的代碼如下：
// methods with prefix w_ are just error checking wrappers from UNP by Stevens
// server
#include "socketwrap.h" // headers necessary and constants like MAXLINE
#include <ctype.h>
void sigchld_handler(int sig);
void str_upper(int connfd);
void toUpperCase(char buffer[], int length);
int main(int argc, char** argv)
{
int listenfd;
int connfd;
pid_t childpid;
struct sockaddr_in serverAddress;
struct sockaddr_in clientAddress;
socklen_t length;
struct sigaction sa;
// Create the socket
listenfd = w_socket(AF_INET, SOCK_STREAM, 0);
// Clear the serverAddress structure
bzero(&serverAddress, sizeof(serverAddress));
// Set up the serverAddress structure
serverAddress.sin_family = AF_INET;
serverAddress.sin_addr.s_addr = htonl(INADDR_ANY);
serverAddress.sin_port = htons(11979);
// Bind the socket to a well-defined port
w_bind(listenfd, (struct sockaddr*) &serverAddress, sizeof(serverAddress));
// Start listening for connections
w_listen(listenfd, BACKLOG);
// Handle any zombie children by using a signal handler
sa.sa_handler = sigchld_handler;
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART;
if(sigaction(SIGCHLD, &sa, NULL) == -1)
{
perror("signal error");
exit(1);
}
printf("Waiting for connections...\n");
while(1)
{
length = sizeof(clientAddress);
connfd = w_accept(listenfd, (struct sockaddr*) &clientAddress, &length);
if(connfd < 0)
{
if(errno == EINTR)
{
continue; // back to while
}
else
{
perror("accept error");
exit(1);
}
}
printf("Obtained connection...\n");
childpid = fork();
if (childpid == 0) /* child process */
{
w_close(listenfd); /* close listening socket */
str_upper(connfd); // process the request
exit(0);
}
w_close(connfd); /* parent closes connected socket */
}
}
void sigchld_handler(int sig)
{
while(waitpid(-1, NULL, WNOHANG) > 0);
}
void str_upper(int connfd)
{
char buffer[MAXLINE];
while(read(connfd, buffer, MAXLINE - 1) > 0)
{
toUpperCase(buffer, strlen(buffer));
write(connfd, buffer, strlen(buffer));
}
}
void toUpperCase(char buffer[], int length)
{
int i;
for(i = 0; i < length - 1; i++)
{
buffer[i] = toupper(buffer[i]);
}
}
// client
#include "socketwrap.h"
void str_cli(int connfd);
int main(int argc, char** argv)
{
int sockfd;
struct sockaddr_in serverAddress;
if(argc != 2)
{
printf("Invalid argument count\n");
printf("Correct usage: tcpcli4 <IPaddress>\n");
exit(1);
}
sockfd = w_socket(AF_INET, SOCK_STREAM, 0);
bzero(&serverAddress, sizeof(serverAddress));
serverAddress.sin_family = AF_INET;
serverAddress.sin_port = htons(11979);
if(inet_pton(AF_INET, argv[1], &serverAddress.sin_addr) <= 0)
{
perror("inet_pton error");
exit(1);
}
w_connect(sockfd, (struct sockaddr*) &serverAddress, sizeof(serverAddress));
str_cli(sockfd);
exit(0);
}
void str_cli(int connfd)
{
char buffer[MAXLINE];
printf("Enter the string to echo: ");
while(fgets(buffer, MAXLINE, stdin) > 0)
{
// Send string to echo server, and retrieve response
write(connfd, buffer, strlen(buffer));
read(connfd, buffer, MAXLINE - 1);
// Output echoed string
printf("Echo response: %s\n", buffer);
printf("Enter the string to echo: ");
}
}
如果您需要更多信息或有什麼不清楚的請通知我
感謝所有回覆
嗯。您是否在任何時候給予更長的輸入，然後輸入更短的時間呢？ – aschepler
嘗試過，是的它沒有問題，如果輸入變得越來越長，但長，然後較短，這樣做。 – john27