minix/lib/ip/nameinfo.c

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#include <arpa/inet.h>
#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netdb.h>
#include <unistd.h>
static size_t first_component_len(const char *s)
{
const char *first = s;
/* find the first dot or end of string */
while (*s && *s != '.')
s++;
/* return length */
return s - first;
}
static int getnameinfo_get_host(const struct sockaddr_in *sockaddr,
char *node, socklen_t nodelen, int flags)
{
struct hostent *hostent;
const char *ipaddr;
/* perform look-up */
if ((flags & NI_NUMERICHOST) != NI_NUMERICHOST)
{
hostent = gethostbyaddr(
(char *) &sockaddr->sin_addr,
sizeof(sockaddr->sin_addr),
AF_INET);
if (hostent && hostent->h_name)
{
/* return the hostname that was found */
if (nodelen <= strlen(hostent->h_name))
return EAI_OVERFLOW;
strcpy(node, hostent->h_name);
return 0;
}
}
if ((flags & NI_NAMEREQD) == NI_NAMEREQD)
return EAI_NONAME;
/* basic implementation to provide numeric values */
ipaddr = inet_ntoa(sockaddr->sin_addr);
if (nodelen <= strlen(ipaddr))
return EAI_OVERFLOW;
strcpy(node, ipaddr);
return 0;
}
static int getnameinfo_get_serv(const struct sockaddr_in *sockaddr,
char *service, socklen_t servicelen, int flags)
{
struct servent *servent;
unsigned short port;
/* perform look-up */
if ((flags & NI_NUMERICSERV) != NI_NUMERICSERV)
{
servent = getservbyport(sockaddr->sin_port,
((flags & NI_DGRAM) == NI_DGRAM) ? "udp" : "tcp");
if (servent && servent->s_name)
{
/* return the service name that was found */
if (strlen(servent->s_name) >= servicelen)
return EAI_OVERFLOW;
strcpy(service, servent->s_name);
return 0;
}
}
/* return port number */
port = ntohs(sockaddr->sin_port);
if (snprintf(service, servicelen, "%u", port) >= servicelen)
return EAI_OVERFLOW;
return 0;
}
/*
* getnameinfo is based on
* http://www.opengroup.org/onlinepubs/009695399/functions/getnameinfo.html
*/
int getnameinfo(const struct sockaddr *sa, socklen_t salen,
char *node, socklen_t nodelen, char *service,
socklen_t servicelen, int flags)
{
int r;
const struct sockaddr_in *sockaddr;
/*
* The following flags are really supported:
* - NI_NUMERICHOST
* - NI_NAMEREQD
* - NI_NUMERICSERV
* - NI_DGRAM
*
* The following flag is not supported:
* - NI_NUMERICSCOPE
*
* The following flags could have been supported but is not implemented:
* - NI_NOFQDN
*/
/* check for invalid parameters; only support IPv4 */
if (sa == NULL)
{
errno = EINVAL;
return EAI_SYSTEM;
}
if (sa->sa_family != AF_INET || salen != sizeof(struct sockaddr_in))
return EAI_FAMILY;
if (flags & ~(NI_NUMERICHOST | NI_NAMEREQD | NI_NUMERICSERV | NI_DGRAM))
return EAI_BADFLAGS;
if ((!node || !nodelen) && (!service || !servicelen))
return EAI_NONAME;
/* look up host */
sockaddr = (const struct sockaddr_in *) sa;
if (node && nodelen > 0)
{
r = getnameinfo_get_host(sockaddr, node, nodelen, flags);
if (r)
return r;
}
/* look up service */
if (service && servicelen > 0)
{
r = getnameinfo_get_serv(sockaddr, service, servicelen, flags);
if (r)
return r;
}
return 0;
}