Question

socket编程的bind函数问题

bzero(&socket_info.address, sizeof(socket_info.address));
socket_info.address.sin_family = AF_INET;
socket_info.address.sin_addr.s_addr = inet_addr(IP) ;
socket_info.address.sin_port = htons(PORT);
socket_info.socket_descriptor = socket(AF_INET, SOCK_DGRAM, 0);
if (socket_info.socket_descriptor == -1) {
perror ("socket call failed");
exit(errno);
}
bind_rc = bind(socket_info.socket_descriptor, (struct sockaddr *)&socket_info.address, sizeof(socket_info.address));
if (bind_rc == -1) {
perror ("bind call failed");
exit (errno);
}

#define IP "192.168.2.6"

这里的IP是我本机的IP，如果使用127.0.0.1代码也都正常。
但是如果使用比如说是局域网内的IP"192.168.2.22"
就出现错误：
bind call failed: Cannot assign requested address

请问大家我的初始化哪里有错误？
是linux下的socket。
htonl(INADDR_ANY); 是任何IP的。对我没任何意义，而且我用的UDP，不是TCP,看你等级那么高也是到处复制粘贴来回答问题的？难道都没看到我问什么吗？
我知道我错在哪里了：bind是绑定本机IP

问上另外一个问题：作为接收端如何做,才能实现指定IP连接?

Answer 1

服务器端程序

/******* 服务器程序 (server.c) ************/
#include
#include
#include
#include
#include
#include
#include
#include

int main(int argc, char *argv[])
{
int sockfd,new_fd;
struct sockaddr_in server_addr;
struct sockaddr_in client_addr;
int sin_size,portnumber;
char hello[]="Hello! Are You Fine?\n";

if(argc!=2)
{
fprintf(stderr,"Usage:%s portnumber\a\n",argv[0]);
exit(1);
}

if((portnumber=atoi(argv[1]))?0)
{
fprintf(stderr,"Usage:%s portnumber\a\n",argv[0]);
exit(1);
}

/* 服务器端开始建立socket描述符 */
if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1)
{
fprintf(stderr,"Socket error:%s\n\a",strerror(errno));
exit(1);
}

/* 服务器端填充 sockaddr结构 */
bzero(&server_addr,sizeof(struct sockaddr_in));
server_addr.sin_family=AF_INET;
server_addr.sin_addr.s_addr=htonl(INADDR_ANY);
server_addr.sin_port=htons(portnumber);

/* 捆绑sockfd描述符 */
if(bind(sockfd,(struct sockaddr *)(&server_addr),sizeof(struct sockaddr))==-1)
{
fprintf(stderr,"Bind error:%s\n\a",strerror(errno));
exit(1);
}

/* 监听sockfd描述符 */
if(listen(sockfd,5)==-1)
{
fprintf(stderr,"Listen error:%s\n\a",strerror(errno));
exit(1);
}

while(1)
{
/* 服务器阻塞,直到客户程序建立连接 */
sin_size=sizeof(struct sockaddr_in);
if((new_fd=accept(sockfd,(struct sockaddr *)(&client_addr),&sin_size))==-1)
{
fprintf(stderr,"Accept error:%s\n\a",strerror(errno));
exit(1);
}

fprintf(stderr,"Server get connection from %s\n",
inet_ntoa(client_addr.sin_addr));
if(write(new_fd,hello,strlen(hello))==-1)
{
fprintf(stderr,"Write Error:%s\n",strerror(errno));
exit(1);
}
/* 这个通讯已经结束 */
close(new_fd);
/* 循环下一个 */
}
close(sockfd);
exit(0);
}
#include
#include
#include
#include
#include
#include
#include
#include

int main(int argc, char *argv[])
{
int sockfd;
char buffer[1024];
struct sockaddr_in server_addr;
struct hostent *host;
int portnumber,nbytes;

if(argc!=3)
{
fprintf(stderr,"Usage:%s hostname portnumber\a\n",argv[0]);
exit(1);
}

if((host=gethostbyname(argv[1]))==NULL)
{
fprintf(stderr,"Gethostname error\n");
exit(1);
}

if((portnumber=atoi(argv[2]))?0)
{
fprintf(stderr,"Usage:%s hostname portnumber\a\n",argv[0]);
exit(1);
}
/* 客户程序开始建立 sockfd描述符 */
if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1)
{
fprintf(stderr,"Socket Error:%s\a\n",strerror(errno));
exit(1);
}
/* 客户程序填充服务端的资料 */
bzero(&server_addr,sizeof(server_addr));
server_addr.sin_family=AF_INET;
server_addr.sin_port=htons(portnumber);
server_addr.sin_addr=*((struct in_addr *)host-?h_addr);
/* 客户程序发起连接请求 */
if(connect(sockfd,(struct sockaddr *)(&server_addr),sizeof(struct sockaddr))==-1)
{
fprintf(stderr,"Connect Error:%s\a\n",strerror(errno));
exit(1);
}
/* 连接成功了 */
if((nbytes=read(sockfd,buffer,1024))==-1)
{
fprintf(stderr,"Read Error:%s\n",strerror(errno));
exit(1);
}
buffer[nbytes]=’\0′;
printf("I have received:%s\n",buffer);
/* 结束通讯 */
close(sockfd);
exit(0);
}
*/
int sock_connect(char *domain,int port)
{
int white_sock;
struct hostent * site;
struct sockaddr_in me;
site = gethostbyname(domain);
if (site==NULL) return -2;
white_sock = socket(AF_INET,SOCK_STREAM,0);
if (white_sock?0) return -1;
memset(&me,0,sizeof(struct sockaddr_in));
memcpy(&me.sin_addr,site-?h_addr_list[0],site-?h_length);
me.sin_family = AF_INET;
me.sin_port = htons(port);
return (connect(white_sock,(struct sockaddr *)&me,sizeof(struct sockaddr))?0) ? -1 : white_sock;
}
*/
/*
客户端程序
int DaemonSocket;
struct sockaddr_in DaemonAddr;
int BindSocket(void)
{
DaemonSocket = socket(AF_INET,SOCK_STREAM,0);
if (DaemonSocket==-1) return 0;
DaemonAddr.sin_family = AF_INET;
DaemonAddr.sin_port = htons(DAEMON_PORT);
if (bind(DaemonSocket,&DaemonAddr,sizeof(DaemonAddr))?0) {
printf("Can not bind!\n");
return 0;
}
if (listen(DaemonSocket,1024)!=0) {
printf("Can not listen!\n");
return 0;
}
return 1;
}

//要查看是否有连线进来，可用以下方式:
int incoming_call(void)
{
fd_set sock;
struct timeval tv;
int t;

FD_ZERO(&sock);
FD_SET(DaemonSocket,&sock);
tv.tv_sec = 60; tv.tv_usec = 0;
t = select(DaemonSocket + 1,&sock,NULL,NULL,&tv);
if (t?=0||!FD_ISSET(DaemonSocket,&sock)) return 0;

printf("incoming…\n");

return 1;
}

//Connect Client
//当我们确认有人进来要求服务时，会需要accept connection，可用以下方式
int ConnectClient(void)
{
int socksize=sizeof(HostAddr);
unsigned char * addr;

ClientSocket = accept(DaemonSocket,(struct sockaddr*)&HostAddr,&socksize);
if (ClientSocket?0) return 0;

addr = (unsigned char *)&HostAddr.sin_addr.s_addr;

printf("incoming address:%d.%d.%d.%d\n",addr[0],addr[1],addr[2],addr[3]);

return 1;
}
*/

Answer 2

进程可以把一个特定的IP地址捆绑到它的套接口上，但是这个IP地址必须是本机的网络接口之一。

从你说得情况来看，可能192.168.2.6并不是你机器的IP地址，你最好先看看自己的IP.