《UNIX 网络编程》 第三章课后习题第三题

试写一个名为inet_pton_loose的函数，它能处理如下情形：如果地址族为AF_INET且inet_pton返回0，那就调用inet_aton看是否成功；类似地，如果地址族为AF_INET6且inet_pton返回0，那么就调用inet_aton看是否成功，若成功返回其IPv4映射的IPv6地址。

#include <stdio.h>  #include <stdlib.h>  #include <arpa/inet.h>  #include <sys/socket.h>  #include <netinet/in.h>  #include <string.h>  /** 具体的转换过程，不做详细注释，有更好的实现方式 **/   int  inet_pton_loose(int family,const char *strptr,void *addrptr)  {         int i = 0;        if(inet_pton(family,strptr,addrptr) == 0){          struct in_addr  v4addr;          if(inet_aton(strptr,&v4addr)    == 1){              if(family == AF_INET){                  memcpy(addrptr,(void *)&v4addr,sizeof(struct in_addr));                   return 1;              }              if(family == AF_INET6){                  struct in6_addr v6addr;                  for(i=0;i<16;i++){                      if(i<10)                          v6addr.s6_addr[i] = 0;                      if(i >= 10 && i < 12)                          v6addr.s6_addr[i] = 0xf;                      if(i >= 12 )                          v6addr.s6_addr[i] = htonl(v4addr.s_addr)>>(16-i-1)*8;                  }                  memcpy(addrptr,(void *)&v6addr,sizeof(struct in6_addr));                  return 1;                                         }             }          return 0;      }             return 1;  }  /** 获取输入，辨别是IPv4 还是IPv6 并做相应的处，理完成后输出用户的输入。没有添加错误处理。 **/  int  main(int argc,char **argv)  {      struct in_addr IPv4addr;      struct in6_addr IPv6addr;      const u_char *strptr;      const char *AddrFlag4 = "AF_INET";      const char *AddrFlag6 = "AF_INET6";      if(strcmp(AddrFlag4,argv[1]) == 0){          if(inet_pton_loose(AF_INET,argv[2],(void *)&IPv4addr) == 1){              strptr = (u_char *)&IPv4addr;              printf("%s---%d.%d.%d.%d\n",argv[1],strptr[0],strptr[1],strptr[2],strptr[3]);              return 1;          }      }      if(strcmp(AddrFlag6,argv[1]) == 0){          if(inet_pton_loose(AF_INET6,argv[2],(void *)&IPv6addr)  == 1){              strptr = (u_char *)&IPv6addr;              printf("%s---%d%d:%d%d:%d%d:%d%d:%d%d:%x%x:%d.%d.%d.%d\n",argv[1],strptr[0],strptr[1],                  strptr[2],strptr[3],strptr[4],strptr[5],strptr[6],strptr[7],strptr[8],strptr[9]                  ,strptr[10],strptr[11],strptr[12],strptr[13],strptr[14],strptr[15]);              return 1;          }      }      return 1;  }  

#include "unp.h"in_addr_t inet_pton_loose(int family, const char *strptr,void *addrptr){    struct in_addr *ap = (struct in_addr *)addrptr;    int result = 0;    if((family == AF_INET) && (inet_pton(family,strptr,addrptr) == 0))    {        printf("the net protocol is IPv4 str is %s\n",strptr);        result = inet_aton(strptr,ap);        printf("result is %d\n",result);        if(result)            return ap->s_addr;        else             return 0;    }    else if ((family == AF_INET6) && (inet_pton(family,strptr,addrptr) == 0))    {        printf("the net protocol is IPv6\n");        result = inet_aton(strptr,ap);        printf("result is %d\n",result);        if(result)        {            return ap->s_addr;        }        else             return 0;    }    return 0;}int main (int argc, char **argv){    //if argv[1] is zero, means AF_INET type, 1 for AF_INET6 type    char s[20];    struct in_addr addr;    in_addr_t addr_result = 0;    if(argc < 2)    {        printf("usage: ./mytest <fa> <addr>\n");        return 1;    }    bzero(&addr,sizeof(struct in_addr));    memset(s,0,sizeof(s));    strcpy(s,argv[2]);    if(atoi(argv[1]) == 0)    {        printf("the net protocol is IPv4\n");        addr_result = inet_pton_loose(AF_INET,s,(void *)&addr);        printf("addr_result is %x\n",addr_result);    }    else if(atoi(argv[1]) == 1)    {        printf("the net protocol is IPv6\n");        addr_result = inet_pton_loose(AF_INET6,s,(void *)&addr);        printf("addr_result is %x\n",addr_result);    }    return 0;    }