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

     1  #define _GNU_SOURCE
     2  #include <sys/socket.h>
     3  #include <netinet/in.h>
     4  #include <netdb.h>
     5  #include <inttypes.h>
     6  #include <errno.h>
     7  #include <string.h>
     8  #include <stdlib.h>
     9  #include "lookup.h"
    10  
    11  #define ALIGN (sizeof(struct { char a; char *b; }) - sizeof(char *))
    12  
    13  int getservbyname_r(const char *name, const char *prots,
    14  	struct servent *se, char *buf, size_t buflen, struct servent **res)
    15  {
    16  	struct service servs[MAXSERVS];
    17  	int cnt, proto, align;
    18  
    19  	*res = 0;
    20  
    21  	/* Don't treat numeric port number strings as service records. */
    22  	char *end = "";
    23  	strtoul(name, &end, 10);
    24  	if (!*end) return ENOENT;
    25  
    26  	/* Align buffer */
    27  	align = -(uintptr_t)buf & ALIGN-1;
    28  	if (buflen < 2*sizeof(char *)+align)
    29  		return ERANGE;
    30  	buf += align;
    31  
    32  	if (!prots) proto = 0;
    33  	else if (!strcmp(prots, "tcp")) proto = IPPROTO_TCP;
    34  	else if (!strcmp(prots, "udp")) proto = IPPROTO_UDP;
    35  	else return EINVAL;
    36  
    37  	cnt = __lookup_serv(servs, name, proto, 0, 0);
    38  	if (cnt<0) switch (cnt) {
    39  	case EAI_MEMORY:
    40  	case EAI_SYSTEM:
    41  		return ENOMEM;
    42  	default:
    43  		return ENOENT;
    44  	}
    45  
    46  	se->s_name = (char *)name;
    47  	se->s_aliases = (void *)buf;
    48  	se->s_aliases[0] = se->s_name;
    49  	se->s_aliases[1] = 0;
    50  	se->s_port = htons(servs[0].port);
    51  	se->s_proto = servs[0].proto == IPPROTO_TCP ? "tcp" : "udp";
    52  
    53  	*res = se;
    54  	return 0;
    55  }