linux 網絡編程函數原型速查

原創

2020-02-21 11:00

兩個結構體
struct sockaddr {
sa_family_t sa_family; /* address family, AF_xxx */
char sa_data[14]; /* 14 bytes of protocol address */
};

/* Structure describing an Internet socket address. */
struct sockaddr_in
{
    __SOCKADDR_COMMON (sin_);
    in_port_t sin_port;   /* Port number. */
    struct in_addr sin_addr;  /* Internet address. */

    /* Pad to size of `struct sockaddr'. */
    unsigned char sin_zero[sizeof (struct sockaddr) -
      __SOCKADDR_COMMON_SIZE -
      sizeof (in_port_t) -
      sizeof (struct in_addr)];
};
主要函數
int socket(int domain, int type, int protocol);
int bind(int sockfd,struct sockaddr *my_addr, int addrlen);
int send(int sockfd, const void *msg, int len, int flags);
int accept(int sockfd, void *addr, int *addrlen);
int listen(int sockfd， int backlog);
int recv(int sockfd,void *buf,int len,unsigned int flags);　　
int sendto(int sockfd, const void *msg,int len,unsigned int flags,const struct sockaddr *to, int tolen);　　　　
int recvfrom(int sockfd,void *buf,int len,unsigned int flags,struct sockaddr *from,int *fromlen);　　
from是一個struct sockaddr類型的變量，該變量保存源機的IP地址及端口號。fromlen常置爲sizeof (struct sockaddr)。

一點解釋
Send()和recv()這兩個函數用於面向連接的socket上進行數據傳輸
Sendto()和recvfrom()用於在無連接的數據報socket方式下進行數據傳輸
調用close()函數來釋放該socket
調用shutdown()函數來關閉該socket
int shutdown(int sockfd,int how);　　
Sockfd是需要關閉的socket的描述符。參數 how允許爲shutdown操作選擇以下幾種方式：　　
·0-------不允許繼續接收數據　　
·1-------不允許繼續發送數據　　
·2-------不允許繼續發送和接收數據

/* Description of data base entry for a single host. *//usr/include 下
struct hostent
{
char *h_name;   /* Official name of host. */
char **h_aliases;  /* Alias list. */
int h_addrtype;  /* Host address type. */
int h_length;   /* Length of address. */
char **h_addr_list;  /* List of addresses from name server. */
#define h_addr h_addr_list[0] /* Address, for backward compatibility. */
};

struct hostent {
         char *h_name; //h_name 爲地址名稱
        char **h_aliases; // 一般是個空字節-它是地址的預備名稱的指針,也可以這樣說它是一個以空指針結尾的可選主機名隊列。
        int h_addrtype; //地址類型; 通常是AF_INET（代表是ipv4）
        int h_length; //地址的比特長度
       char **h_addr_list; //主機網絡地址指針，零字節-主機網絡地址指針（空指針結尾的主機地址的列表，返回的地址是以網絡順序排列的）。
               }

      gethostbyname() 成功時返回一個指向結構體 hostent 的指針，失敗時是個空 (NULL) 指針
               gethostbyaddr()

      htonl()：把32位值從主機字節序轉換成網絡字節序·
      htons()：把16位值從主機字節序轉換成網絡字節序·
      ntohl()：把32位值從網絡字節序轉換成主機字節序·
      ntohs()：把16位值從網絡字節序轉換成主機字節序

   int (*release)(struct socket *sock);
   int (*bind)(struct socket *sock, struct sockaddr *myaddr, int sockaddr_len);
   int (*connect)(struct socket *sock, struct sockaddr *vaddr, int sockaddr_len, int flags);

   int (*accept)(struct socket *sock,struct socket *newsock, int flags);

   unsigned int (*poll)(struct file *file, struct poll_table_struct *wait);
   int (*ioctl)(struct socket *sock, unsigned int cmd, unsigned long arg);
   int (*listen)(struct socket *sock, int len);
   int (*shutdown)(struct socket *sock, int flags);
   int (*setsockopt)(struct socket *sock, int level, int optname, char __user *optval, int optlen);
   int (*getsockopt)(struct socket *sock, int level, int optname, char __user *optval, int __user *optlen);
   int (*sendmsg)(struct kiocb *iocb, struct socket *sock,struct msghdr *m, size_t total_len);
   int (*recvmsg)(struct kiocb *iocb, struct socket *sock,struct msghdr *m, size_t total_len, int flags);
   int (*mmap)(struct file *file, struct socket *sock,struct vm_area_struct * vma);
   ssize_t (*sendpage)(struct socket *sock, struct page *page,int offset, size_t size, int flags);