C语言 绑定失败：无法分配请求的地址
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bind failed: Cannot assign requested address
提问by ffledgling
I'm trying to write a C program that listens on a port on my machine. I'm running into a strange error.
我正在尝试编写一个 C 程序来侦听我机器上的一个端口。我遇到了一个奇怪的错误。
Whenever I try to bind the socket to a fixed ip (either 127.0.0.1or my actual IP) I get a "bind failed: Cannot assign requested address"error.
However when I pass INADDR_ANYto the bind as the address to bind to, it works.
每当我尝试将套接字绑定到固定 IP（127.0.0.1或我的实际 IP）时，我都会收到"bind failed: Cannot assign requested address"错误消息。但是，当我将INADDR_ANY绑定作为要绑定到的地址传递给它时，它会起作用。
These are the only two IPs I have so it can't be that the 0.0.0.0 works because of some other IP address I have available.
这是我仅有的两个 IP，因此 0.0.0.0 不能工作，因为我有其他一些可用的 IP 地址。
Here is the code:
这是代码：
#include<sys/types.h>
#include<stdio.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<errno.h>
#include<stdlib.h>
#include<string.h>
int main()
{
int port = 1234; /* port number */
int rqst; /* socket accepting the request */
socklen_t alen; /* length of address structure */
struct sockaddr_in my_addr; /* address of this service */
struct sockaddr_in client_addr; /* client's address */
int sockoptval = 1;
int svc;
/* create a TCP/IP socket */
if ((svc = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
perror("cannot create socket");
exit(1);
}
/* allow immediate reuse of the port */
setsockopt(svc, SOL_SOCKET, SO_REUSEADDR, &sockoptval, sizeof(int));
/* bind the socket to our source address */
memset((char*)&my_addr, 0, sizeof(my_addr)); /* 0 out the structure */
my_addr.sin_family = AF_INET; /* address family */
my_addr.sin_port = htons(port);
//my_addr.sin_addr.s_addr = htonl(INADDR_ANY); /* Works! */
my_addr.sin_addr.s_addr = htonl(inet_addr("127.0.0.1")); /* Fails! */
if (bind(svc, (struct sockaddr *)&my_addr, sizeof(my_addr)) < 0) {
perror("bind failed");
exit(1);
}
printf("Listening on %d\n", my_addr.sin_addr.s_addr);
/* set the socket for listening (queue backlog of 5) */
if (listen(svc, 5) < 0) {
perror("listen failed");
exit(1);
}
/* loop, accepting connection requests */
for (;;) {
while ((rqst = accept(svc, (struct sockaddr *)&client_addr, &alen)) < 0) {
/* we may break out of accept if the system call */
/* was interrupted. In this case, loop back and */
/* try again */
if ((errno != ECHILD) && (errno != ERESTART) && (errno != EINTR)) {
perror("accept failed");
exit(1);
}
}
/* the socket for this accepted connection is rqst */
}
}
回答by cnicutar
The function inet_addrreturns the address already in network order:
该函数inet_addr返回已按网络顺序排列的地址：
The inet_addr() function converts the Internet host address cp from IPv4 numbers-and-dots notation into binary data in network byte order
inet_addr() 函数将 Internet 主机地址 cp 从 IPv4 数字和点表示法转换为网络字节顺序的二进制数据
So drop the htonl.
所以放下htonl.
