818ping中函数指针及结构体的使用

首先定义函数和结构体

/* function prototypes */
void     init_v6(void);
void     proc_v4(char *, ssize_t, struct msghdr *, struct timeval *);
void     proc_v6(char *, ssize_t, struct msghdr *, struct timeval *);
void     send_v4(void);
void     send_v6(void);
void     readloop(void);
void     sig_alrm(int);
void     tv_sub(struct timeval *, struct timeval *);

struct proto {
  void     (*fproc)(char *, ssize_t, struct msghdr *, struct timeval *);
  void     (*fsend)(void);
  void     (*finit)(void);
  struct sockaddr  *sasend;    /* sockaddr{} for send, from getaddrinfo */
  struct sockaddr  *sarecv;    /* sockaddr{} for receiving */
  socklen_t        salen;        /* length of sockaddr{}s */
  int               icmpproto;    /* IPPROTO_xxx value for ICMP */
} *pr;
然后初始化结构体
点击(此处)折叠或打开struct proto    proto_v4 = { proc_v4, send_v4, NULL, NULL, NULL, 0, IPPROTO_ICMP };然后初始化指针
点击(此处)折叠或打开pr = &proto_v6;然后调用方式
(*pr->fproc)(recvbuf, n, &msg, &tval);