为什么不能将linux服务仅绑定到环回？

发布于 2024-10-11 03:07:14 字数 486 浏览 3 评论 0原文

我正在编写一个服务器应用程序，它将在临时端口上提供服务，我只想在环回接口上访问该服务。为了做到这一点，我编写如下代码：

struct sockaddr_in bind_addr;

memset(&bind_addr,0,sizeof(bind_addr));
bind_addr.sin_family = AF_INET;
bind_addr.sin_port = 0;
bind_addr.sin_addr.s_addr = htonl(inet_addr("127.0.0.1"));
rcd = ::bind(
   socket_handle,
   reinterpret_cast<struct sockaddr *>(&bind_addr),
   sizeof(bind_addr));

对bind()的调用的返回值为-1，errno的值为99（无法分配请求的地址）。失败是因为 inet_addr() 已经按网络顺序返回其结果还是有其他原因？

原文

I am writing a server application that will provide a service on an ephemeral port that I only want accessible on the loopback interface. In order to do this, I am writing code like the following:

struct sockaddr_in bind_addr;

memset(&bind_addr,0,sizeof(bind_addr));
bind_addr.sin_family = AF_INET;
bind_addr.sin_port = 0;
bind_addr.sin_addr.s_addr = htonl(inet_addr("127.0.0.1"));
rcd = ::bind(
   socket_handle,
   reinterpret_cast<struct sockaddr *>(&bind_addr),
   sizeof(bind_addr));

The return value for this call to bind() is -1 and the value of errno is 99 (Cannot assign requested address). Is this failing because inet_addr() already returns its result in network order or is there some other reason?

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最美的太阳 2024-10-18 03:07:14

应该避免使用inet_addr，因为有一种更明智的构造struct sockaddr的方法（这意味着它也废弃了gethostby*）：

#include <netdb.h>

/* Error checking omitted for brevity */
struct addrinfo hints = {.ai_flags = AI_PASSIVE};
struct addrinfo *res;
getaddrinfo("::1", NULL, &hints, &res); /* or 127.0.0.1 if you are 60+ */
bind(fd, res->ai_addr, res->ai_addrlen);
freeaddrinfo(res);

inet_addr should be avoided, for there is a much saner method of constructing struct sockaddrs (which means it also obsoletes gethostby*):

#include <netdb.h>

/* Error checking omitted for brevity */
struct addrinfo hints = {.ai_flags = AI_PASSIVE};
struct addrinfo *res;
getaddrinfo("::1", NULL, &hints, &res); /* or 127.0.0.1 if you are 60+ */
bind(fd, res->ai_addr, res->ai_addrlen);
freeaddrinfo(res);

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