一个简单点的阻塞式tcp服务器如下所示：
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#include <stdio.h>#include <string.h>#include <sys/socket.h>#include <netinet/in.h> int main(int
argc, char**argv)
{ int
listenfd,connfd,n, ret;
struct
sockaddr_in servaddr, cliaddr;
socklen_t clilen;
pid_t childpid;
char
mesg[1000], *peeraddr;
listenfd = socket(AF_INET, SOCK_STREAM, 0);
if
(listenfd < 0) {
printf("create socket error\n");
return
-1;
}
printf("create socket success\n");
memset(&servaddr, 0, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(6789);
ret = bind(listenfd, (struct
sockaddr *)&servaddr, sizeof(servaddr));
if
(ret == -1) {
printf("bind error\n");
return
-1;
}
printf("bind success\n");
ret = listen(listenfd, 1024);
if
(ret == -1) {
printf("listen error\n");
return
-1;
}
printf("listening...\n");
for
(;;) {
clilen = sizeof(cliaddr);
connfd = accept(listenfd, (struct
sockaddr *)&cliaddr, &clilen);
printf("Accept request from %s\n", inet_ntoa(cliaddr.sin_addr));
n = read(connfd, mesg, 1000);
if
(n < 0) {
printf("read error!\n");
}
printf("Received:%s\n", mesg);
close(connfd);
}
} |
编译期间没有遇到问题。运行的时候程序在47行收到了segment fault错误。用man手册查看inet_ntoa，调用方式如下：
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char
*inet_ntoa(struct
in_addr in);
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cliaddr的类型定义是：
struct sockaddr_in { /* in netinet/in.h */
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<em id="__mceDel"> sa_family_t sin_family;
in_port_t sin_port;
struct
in_addr sin_addr;
unsigned char
sin_zero[sizeof(struct
sockaddr) - sizeof(sa_family_t) - sizeof(in_port_t), sizeof(struct
in_addr)];
};</em> |
乍一看，没什么问题啊，怎么会出现段错误呢？
捣腾了半天，才发现是缺少了inet_ntoa所在的头文件 arpa/inet.h，包含该头文件即可。好坑。