网络编程中的一个错误,搞不定,求助大家

yufeng8552 · 发表于 2004-1-3 14:28:51

最近搞网络编程,理论是学习了不少,实践起来真不是那么回事,搞了个最简单的TCP协议的Server-Client试验了下,还有一个错误不能搞定,希望有人能指正一下

[root@BillingServer unix]# gcc -o PRG4_1 PRG4_1.C
PRG4_1.C: In function `int main()':
PRG4_1.C:55: invalid conversion from `int*' to `socklen_t*'
PRG4_1.C:69:2: warning: no newline at end of file

// server.c
#include <stdio.h> /* These are the usual header files */
#include <strings.h> /* for bzero() */
#include <unistd.h> /* for close() */
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netinet/tcp.h>
#include <stdlib.h>
#include <errno.h>
#include <netdb.h>
#define PORT 1234 /* Port that will be opened */
#define BACKLOG 1 /* Number of allowed connections */
main()
{
int listenfd, connectfd; /* socket descriptors */
struct sockaddr_in server; /* server's address information */
struct sockaddr_in client; /* client's address information */
int sin_size;
/* Create TCP socket */
if ((listenfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
{
/* handle exception */
perror("Creating socket failed.");
exit(1);
}
/* set socket can be reused */
int opt = SO_REUSEADDR;
setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
bzero(&server,sizeof(server)); /* fill server with 0s */
server.sin_family=AF_INET;
server.sin_port=htons(PORT);
server.sin_addr.s_addr = htonl (INADDR_ANY);
if (bind(listenfd, (struct sockaddr *)&server, sizeof(struct sockaddr)) == -1)
{
/* handle exception */
perror("Bind error.");
exit(1);
}
if(listen(listenfd,BACKLOG) == -1)
{
/* calls listen() */
perror("listen() error\n");
exit(1);
}
sin_size = sizeof(struct sockaddr_in);
if ((connectfd = accept(listenfd,(struct sockaddr *)&client,&sin_size))==-1)
{
/* calls accept() */
perror("accept() error\n");
exit(1);
}
/* prints client's IP */
printf("You got a connection from %s\n",inet_ntoa(client.sin_addr) );
/* send to the client welcome message */
send(connectfd,"Welcome to my server.\n",22,0);
close(connectfd); /* close connectfd */
close(listenfd); /* close listenfd */
}

复制代码

yufeng8552 · 发表于 2004-1-3 14:29:56

//client.c
#include <stdio.h>
#include <unistd.h>
#include <strings.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h> /* netbd.h is needed for struct hostent */
#include <netinet/ip.h>
#include <netinet/tcp.h>
#include <stdlib.h>
#include <errno.h>
#define PORT 1234 /* Open Port on Remote Host */
#define MAXDATASIZE 100 /* Max number of bytes of data */
int main(int argc, char *argv[])
{
int fd, numbytes; /* files descriptors */
char buf[MAXDATASIZE]; /* buf will store received text */
struct hostent *he; /* structure that will get information about remote host */
struct sockaddr_in server; /* server's address information */
if (argc !=2)
{
/* this is used because our program will need one argument (IP) */
printf("Usage: %s <IP Address>\n",argv[0]);
exit(1);
}
if ((he=gethostbyname(argv[1]))==NULL)
{
/* calls gethostbyname() */
printf("gethostbyname() error\n");
exit(1);
}
if ((fd=socket(AF_INET, SOCK_STREAM, 0))==-1)
{
/* calls socket() */
printf("socket() error\n");
exit(1);
}
bzero(&server,sizeof(server));
server.sin_family = AF_INET;
server.sin_port = htons(PORT); /* htons() is needed again */
server.sin_addr = *((in_addr *)he->h_addr); /*he->h_addr passes "*he"'s info to "h_addr" */
if(connect(fd, (struct sockaddr *)&server,sizeof(struct sockaddr))==-1)
{
/* calls connect() */
printf("connect() error\n");
exit(1);
}
if ((numbytes=recv(fd,buf,MAXDATASIZE,0)) == -1)
{
/* calls recv() */
printf("recv() error\n");
exit(1);
}
buf[numbytes]='\0';
printf("Server Message: %s\n",buf); /* it prints server's welcome message */
close(fd); /* close fd */
}

复制代码

yufeng8552 · 发表于 2004-1-3 14:32:24

出现的错误是
[root@BillingServer unix]# gcc -o PRG4_1 PRG4_1.C
PRG4_1.C: In function `int main()':
PRG4_1.C:55: invalid conversion from `int*' to `socklen_t*'
PRG4_1.C:69:2: warning: no newline at end of file

yufeng8552 · 发表于 2004-1-3 15:21:52

http://hylinux.3322.org/showarti ... warticle&id=334

gyb997 · 发表于 2004-1-3 21:11:30

你试验试验，把你的头文件的顺序调换一下，看看行不？
我以前好像遇到你这样的问题

libinary · 发表于 2004-1-4 03:41:39

我编译了一下你的程序，没遇到你说的错误。
不过client程序的：
server.sin_addr = *((in_addr *)he->h_addr); /*he->h_addr passes "*he"'s info to "h_addr" */
应该改成：
if(inet_aton(he->h_addr, &server.sin_addr) == 0){
fprintf(stderr, "inet_aton error\n");
exit(-1);
}

libinary · 发表于 2004-1-4 03:46:54

看一下man gethostbyname

struct hostent {
char *h_name; /* official name of host */
char **h_aliases; /* alias list */
int h_addrtype; /* host address type */
int h_length; /* length of address */
char **h_addr_list; /* list of addresses */
}
#define h_addr h_addr_list[0] /* for backward compatibility */

复制代码

h_addr的类型是char *，不能直接赋值给sin_addr

yufeng8552 · 发表于 2004-1-4 11:22:40

我问过其他地方，有个老兄的解释是
PRG4_1.C:55: invalid conversion from `int*' to `socklen_t*'

把变量类型改改，从int改为socklen_t
后来我靠这样编译过去了，也没有出现版主提到的客户端错误呢，不知为何

home · 发表于 2004-1-4 15:07:56

占位贴！！

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网络编程中的一个错误,搞不定,求助大家

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