github.com/afumu/libc@v0.0.6/musl/src/network/gethostbyname2_r.c (about)

     1  #define _GNU_SOURCE
     2  
     3  #include <sys/socket.h>
     4  #include <netdb.h>
     5  #include <string.h>
     6  #include <netinet/in.h>
     7  #include <errno.h>
     8  #include <stdint.h>
     9  #include "lookup.h"
    10  
    11  int gethostbyname2_r(const char *name, int af,
    12  	struct hostent *h, char *buf, size_t buflen,
    13  	struct hostent **res, int *err)
    14  {
    15  	struct address addrs[MAXADDRS];
    16  	char canon[256];
    17  	int i, cnt;
    18  	size_t align, need;
    19  
    20  	*res = 0;
    21  	cnt = __lookup_name(addrs, canon, name, af, AI_CANONNAME);
    22  	if (cnt<0) switch (cnt) {
    23  	case EAI_NONAME:
    24  		*err = HOST_NOT_FOUND;
    25  		return ENOENT;
    26  	case EAI_AGAIN:
    27  		*err = TRY_AGAIN;
    28  		return EAGAIN;
    29  	default:
    30  	case EAI_FAIL:
    31  		*err = NO_RECOVERY;
    32  		return EBADMSG;
    33  	case EAI_MEMORY:
    34  	case EAI_SYSTEM:
    35  		*err = NO_RECOVERY;
    36  		return errno;
    37  	}
    38  
    39  	h->h_addrtype = af;
    40  	h->h_length = af==AF_INET6 ? 16 : 4;
    41  
    42  	/* Align buffer */
    43  	align = -(uintptr_t)buf & sizeof(char *)-1;
    44  
    45  	need = 4*sizeof(char *);
    46  	need += (cnt + 1) * (sizeof(char *) + h->h_length);
    47  	need += strlen(name)+1;
    48  	need += strlen(canon)+1;
    49  	need += align;
    50  
    51  	if (need > buflen) return ERANGE;
    52  
    53  	buf += align;
    54  	h->h_aliases = (void *)buf;
    55  	buf += 3*sizeof(char *);
    56  	h->h_addr_list = (void *)buf;
    57  	buf += (cnt+1)*sizeof(char *);
    58  
    59  	for (i=0; i<cnt; i++) {
    60  		h->h_addr_list[i] = (void *)buf;
    61  		buf += h->h_length;
    62  		memcpy(h->h_addr_list[i], addrs[i].addr, h->h_length);
    63  	}
    64  	h->h_addr_list[i] = 0;
    65  
    66  	h->h_name = h->h_aliases[0] = buf;
    67  	strcpy(h->h_name, canon);
    68  	buf += strlen(h->h_name)+1;
    69  
    70  	if (strcmp(h->h_name, name)) {
    71  		h->h_aliases[1] = buf;
    72  		strcpy(h->h_aliases[1], name);
    73  		buf += strlen(h->h_aliases[1])+1;
    74  	} else h->h_aliases[1] = 0;
    75  
    76  	h->h_aliases[2] = 0;
    77  
    78  	*res = h;
    79  	return 0;
    80  }