如何在getaddrinfo中处理这个指针？

Question

警告:请像我这样的菜鸟一样对待我.这是我的第一个"真正的"C程序.所以,如果我不理解某些事情,那就是原因.

我正在尝试按照Beej的网络编程指南中的示例制作聊天服务器.它被推荐,所以你去.

我想让一个函数接受一个指向结构的指针,修改该指针中的属性,并在传递的端口上设置一个监听器.在下面的代码中,我收到了分段错误,老实说,我无法弄清楚原因.怪我是绿色的.(如果需要,在Ubuntu上使用Netbeans 6.8开发):

#define PORT "4400"

typedef struct {
    int port;
    fd_set *connections;
    int connections_count;
    int listener;
    struct addrinfo address;
    struct addrinfo socket_hints;
} Server;

typedef struct {
    struct sockaddr_storage address;    // User's address
    int fs_id;                  // ID to the socket they belong to
    char *name;                 // Pointer to the user's name
    struct User *nextUser;      // Next user in the list
} User;

void initialize_server(Server *passed_server, char *port) {
    struct addrinfo *temp;
    int result;

    // Set up the server hints
    memset(&passed_server->socket_hints, 0, sizeof(struct addrinfo));
    passed_server->socket_hints.ai_family = AF_UNSPEC;
    passed_server->socket_hints.ai_socktype = SOCK_STREAM;
    passed_server->socket_hints.ai_flags = AI_PASSIVE;

    result = getaddrinfo(NULL, port, &passed_server->socket_hints, &temp);
    printf("Result: %d\n", result);
}

int main(int argc, char** argv) {
    // Set up socket stuff
    Server *server; // Set up the server
    memset(server, 0, sizeof(Server));

    fd_set read_sockets; // Master socket holder and sockets to read
    int new_connection; // Holds the socket ID of the new connection
    socklen_t address_length; // Used to hold the length of the address from the user
    struct addrinfo;

    // Useful sets
    char buffer[1024];
    int bytes_recieved;
    int yes = 1; // For SETOPT

    // Set up server info on defined port
    initialize_server(server, PORT);
    FD_ZERO(&read_sockets);

    return (EXIT_SUCCESS);
}

如果你需要完整的代码(我想我发布了所有必需的代码),你可以在下面找到一个链接.在此先感谢任何帮助或尝试!

http://pastebin.org/529545

Answer 1

这条线:

Server *server;

实际上并没有为服务器结构分配任何空间,仅用于指向一个服务器结构的指针,该指针设置为随机值.

看起来你需要的改变是:

Server *server = malloc (sizeof (Server));

它实际上为你分配了一些内存.

想想差异如下:

Server *server;              |  Server *server = malloc (sizeof (Server));
       +----------+          |         +---------+     +-----------+
server | ???????? | --> ???  |  server | pointer | --> | structure |
       +----------+          |         +---------+     +-----------+