Question

我认为准确的代码并不重要。相反，我会给出strace输出：

socket(AF_INET, SOCK_STREAM, IPPROTO_IP) = 5
fcntl(5, F_SETFL, O_WRONLY|O_NONBLOCK)  = 0
epoll_ctl(3, EPOLL_CTL_ADD, 5, {EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLET, {u32=209357450, u64=94373525752458}}) = 0
setsockopt(5, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
bind(5, {sa_family=AF_INET, sin_port=htons(31337), sin_addr=inet_addr("0.0.0.0")}, 16) = 0
listen(5, 10)                           = 0
accept(5, 0x7f2a6aade440, [110])        = -1 EAGAIN (Resource temporarily unavailable)
stat("/etc/localtime", {st_mode=S_IFREG|0644, st_size=2265, ...}) = 0
stat("/etc/localtime", {st_mode=S_IFREG|0644, st_size=2265, ...}) = 0
stat("/etc/localtime", {st_mode=S_IFREG|0644, st_size=2265, ...}) = 0
stat("/etc/localtime", {st_mode=S_IFREG|0644, st_size=2265, ...}) = 0
write(1, "\33[1;30m09:44:34.625\33[0m\342\224\202\33[36m0"..., 130) = 130
socket(AF_INET6, SOCK_STREAM, IPPROTO_IP) = 6
fcntl(6, F_SETFL, O_WRONLY|O_NONBLOCK)  = 0
epoll_ctl(3, EPOLL_CTL_ADD, 6, {EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLET, {u32=209357482, u64=94373525752490}}) = 0
setsockopt(6, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
bind(6, {sa_family=AF_INET6, sin6_port=htons(31337), inet_pton(AF_INET6, "::", &sin6_addr), sin6_flowinfo=htonl(0), sin6_scope_id=0}, 28) = -1 EADDRINUSE (Address already in use)

我们可以看到套接字5（IPv4）成功绑定到任何端口：31337，但是当我尝试绑定套接字6（IPv6）时，它失败并显示EADDRINUSE。

您还可以看到我在两个套接字上都设置了SO_REUSEADDR，所以我相信这个问题不应该发生。

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 17.10
Release:        17.10
Codename:       artful

Answer 1

您无需同时侦听IPv4和IPv6，因为侦听IPv6连接就足够了。传入的IPv4连接将由IPv6连接的套接字列表处理。客户端地址可能会以::FFFF:192.168.1.1的格式显示。

无法一起收听IPv4和IPv6（已在使用的地址）

1 个答案: