github.com/afumu/libc@v0.0.6/musl/src/network/inet_pton.c (about)

     1  #include <sys/socket.h>
     2  #include <arpa/inet.h>
     3  #include <ctype.h>
     4  #include <errno.h>
     5  #include <string.h>
     6  
     7  static int hexval(unsigned c)
     8  {
     9  	if (c-'0'<10) return c-'0';
    10  	c |= 32;
    11  	if (c-'a'<6) return c-'a'+10;
    12  	return -1;
    13  }
    14  
    15  int inet_pton(int af, const char *restrict s, void *restrict a0)
    16  {
    17  	uint16_t ip[8];
    18  	unsigned char *a = a0;
    19  	int i, j, v, d, brk=-1, need_v4=0;
    20  
    21  	if (af==AF_INET) {
    22  		for (i=0; i<4; i++) {
    23  			for (v=j=0; j<3 && isdigit(s[j]); j++)
    24  				v = 10*v + s[j]-'0';
    25  			if (j==0 || (j>1 && s[0]=='0') || v>255) return 0;
    26  			a[i] = v;
    27  			if (s[j]==0 && i==3) return 1;
    28  			if (s[j]!='.') return 0;
    29  			s += j+1;
    30  		}
    31  		return 0;
    32  	} else if (af!=AF_INET6) {
    33  		errno = EAFNOSUPPORT;
    34  		return -1;
    35  	}
    36  
    37  	if (*s==':' && *++s!=':') return 0;
    38  
    39  	for (i=0; ; i++) {
    40  		if (s[0]==':' && brk<0) {
    41  			brk=i;
    42  			ip[i&7]=0;
    43  			if (!*++s) break;
    44  			if (i==7) return 0;
    45  			continue;
    46  		}
    47  		for (v=j=0; j<4 && (d=hexval(s[j]))>=0; j++)
    48  			v=16*v+d;
    49  		if (j==0) return 0;
    50  		ip[i&7] = v;
    51  		if (!s[j] && (brk>=0 || i==7)) break;
    52  		if (i==7) return 0;
    53  		if (s[j]!=':') {
    54  			if (s[j]!='.' || (i<6 && brk<0)) return 0;
    55  			need_v4=1;
    56  			i++;
    57  			break;
    58  		}
    59  		s += j+1;
    60  	}
    61  	if (brk>=0) {
    62  		memmove(ip+brk+7-i, ip+brk, 2*(i+1-brk));
    63  		for (j=0; j<7-i; j++) ip[brk+j] = 0;
    64  	}
    65  	for (j=0; j<8; j++) {
    66  		*a++ = ip[j]>>8;
    67  		*a++ = ip[j];
    68  	}
    69  	if (need_v4 && inet_pton(AF_INET, (void *)s, a-4) <= 0) return 0;
    70  	return 1;
    71  }