protoent

   protoent   

 

 protoent 结构体描述：  

/* Description of data base entry for a single service.  */
struct protoent
{
  char *p_name;            /* Official protocol name.  */
  char **p_aliases;        /* Alias list.  */
  int p_proto;             /* Protocol number.  */
};

 

 相关函数：

/* Open protocol data base files and mark them as staying open even
   after a later search if STAY_OPEN is non-zero.

   This function is a possible cancellation point and therefore not
   marked with __THROW.  */
extern void setprotoent (int __stay_open);

/* Close protocol data base files and clear `stay open' flag.

   This function is a possible cancellation point and therefore not
   marked with __THROW.  */
extern void endprotoent (void);

/* Get next entry from protocol data base file.  Open data base if
   necessary.

   This function is a possible cancellation point and therefore not
   marked with __THROW.  */
extern struct protoent *getprotoent (void);

/* Return entry from protocol data base for network with NAME.

   This function is a possible cancellation point and therefore not
   marked with __THROW.  */
extern struct protoent *getprotobyname (__const char *__name);

/* Return entry from protocol data base which number is PROTO.

   This function is a possible cancellation point and therefore not
   marked with __THROW.  */
extern struct protoent *getprotobynumber (int __proto);

 

 测试代码： 

 1 #include <stdio.h>
 2 #include <netdb.h>
 3 
 4 int main()
 5 {
 6     int stayopen = 1;
 7     struct protoent *proto;
 8     char **ptr;
 9 
10     /* 打开协议数据库 */
11     setprotoent(stayopen);
12 
13     /* 逐项扫描登记项 */
14     while(1)
15     {
16         proto = getprotoent();
17 
18         if( proto != (struct protoent *)0 )
19         {
20             printf("Official name : %s\n", proto->p_name);
21 
22             for(ptr=proto->p_aliases; *ptr != 0; ptr++)
23                 printf("alias: %s\n", *ptr);
24 
25             printf("proto: %d\n\n", proto->p_proto);
26         }
27         else
28             break;
29     }
30 
31     /* 关闭协议数据库 */
32     endprotoent();
33 
34     /* 通过名字察看协议 */
35     printf("getprotobyname [ip]: \n");
36     if( 0 != (proto = getprotobyname("ip")) )
37     {
38         for(ptr=proto->p_aliases; *ptr != 0; ptr++)
39             printf("alias: %s\n", *ptr);
40     }
41     else
42         printf("failure ...\n");
43 
44     /* 通过协议号（按主机字节顺序）察看协议 */
45     printf("getprotobynumber [1]: \n");
46     if( 0 != (proto = getprotobynumber(1)) )
47     {
48         printf("name: %s\n", proto->p_name);
49     }
50     else
51         printf("failue ...\n");
52 
53     return 0;
54 }

 

 运行截图：

 

posted @ 2012-06-03 17:05  hp+y  Views(1027)  Comments(0)  Edit  收藏  举报