C在特定IP上打开套接字

Question

可以使用2种不同的静态IP(IPv4)访问我的网站.

是否可以打开到另一台服务器的TCP连接,指定哪两个IP用作返回地址？

xxxx(我的服务器)=> zzzz(目标服务器)
yyyy(我的服务器)=> zzzz(目标服务器)

为简单起见,省略了此示例中的错误检查等:

struct addrinfo hints, *result;
hints.ai_flags = 0;
hints.ai_family = AF_INET;
hints.ai_socktype = SOCK_STREAM;
hints.ai_protocol = IPPROTO_TCP;
hints.ai_addrlen = 0;
hints.ai_canonname = NULL;
hints.ai_addr = NULL;
hints.ai_next = NULL;

getaddrinfo(domain, "80", &hints, &result);

socket(result->ai_family, result->ai_socktype, result->ai_protocol);

Answer 1

就像@hochl说的那样,你使用bind系统调用:

struct sockaddr_in sin = { 0 };
int sock;

/* Create a socket address, with a specific port and (local) ipnumber */
sin.sin_family = AF_INET;
sin.sin_port = htons(80);
inet_aton("1.2.3.4", &sin.sin_addr);

/* Create socket */
sock = socket(AF_INET, SOCK_STREAM, 0);

/* Bind socket to the local address */
bind(sock, (struct sockaddr *) &sin, sizeof(sin));

/* Now connect to remote server... */
/* connect(...) */

应该注意的inet_aton是,通常不鼓励使用,有利于inet_pton.