1. 所在的结构体定义
struct mg_server {
sock_t listening_sock;
union socket_address lsa; // Listening socket address
struct ll active_connections;
struct ll uri_handlers;
char *config_options[NUM_OPTIONS];
void *server_data;
void *ssl_ctx; // SSL context
sock_t ctl[2]; // Control socketpair. Used to wake up from select() call
};
2. 变量初始化
mg_create_server函数: server->listening_sock = INVALID_SOCKET;
3. 变量的赋值
mg_set_option函数 server->listening_sock = open_listening_socket(&server->lsa);
open_listening_socket函数的具体实现: static sock_t open_listening_socket(union socket_address *sa) {
sock_t on = 1, sock = INVALID_SOCKET;
if (( sock = socket(sa->sa.sa_family, SOCK_STREAM, 6)) == INVALID_SOCKET ||
setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *) &on, sizeof(on)) ||
bind(sock, &sa->sa, sa->sa.sa_family == AF_INET ?
sizeof(sa->sin) : sizeof(sa->sa)) != 0 ||
listen(sock, SOMAXCONN) != 0) {
closesocket(sock);
sock = INVALID_SOCKET;
}
return sock;
}
mg_set_listening_socket函数 server->listening_sock = sock;
注:上面两处赋值的地方,其中mg_set_listening_socket接口只在特殊情况下调用,暂不讨论; mg_set_option接口调用是必须要进行的,而且必须设置参数为"listening_port"的值,mg_set_option中就会open_listening_socket,然后赋值给server->listening_sock。 "listening_port"的默认值是NULL "listening_port", NULL, 如果不设置"listening_port"的值,server->listening_sock保持为初始化时的INVALID_SOCKET,在mg_poll_server时就会判断为非法值,直接return: if (server->listening_sock == INVALID_SOCKET) return 0;
4. 变量的使用
mg_poll_server函数中监听server->listening_sock套接字: add_to_set(server->listening_sock, &read_set, &max_fd); if (FD_ISSET(server->listening_sock, &read_set))
accept_new_connection函数,创建新的connection socket sock = accept(server->listening_sock, &sa.sa, &len)
5. 其他使用的地方
mg_set_option函数,open_listening_socket成功之后,设置非阻塞模式: set_non_blocking_mode(server->listening_sock);
mg_get_listening_socket函数,读取listening_sock: return server->listening_sock;
6. 销毁套接字
mg_destroy_server函数: closesocket((*server)->listening_sock);
mg_set_option函数中,如果设置LISTENING_PORT时,已经存在listening_sock,则需要先关闭它: if (server->listening_sock != INVALID_SOCKET) { closesocket(server->listening_sock); }
mg_set_listening_socket函数,同理,如果已经存在listening_sock,则需要先关闭它: if (server->listening_sock != INVALID_SOCKET) {
closesocket(server->listening_sock);
}