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/*
* Replacement for a missing getnameinfo.
*
* This is an implementation of getnameinfo for systems that don't have one so
* that networking code can use a consistant interface without #ifdef. It is
* a fairly minimal implementation, with the following limitations:
*
* - IPv4 support only. IPv6 is not supported.
* - NI_NOFQDN is ignored.
* - Not thread-safe due to gethostbyaddr, getservbyport, and inet_ntoa.
*
* The last two issues could probably be easily remedied, but haven't been
* needed so far. Adding IPv6 support isn't worth it; systems with IPv6
* support should already support getnameinfo natively.
*
* The canonical version of this file is maintained in the rra-c-util package,
* which can be found at <https://www.eyrie.org/~eagle/software/rra-c-util/>.
*
* Written by Russ Allbery <eagle@eyrie.org>
* Copyright 2005 Russ Allbery <eagle@eyrie.org>
* Copyright 2008, 2011, 2013-2014
* The Board of Trustees of the Leland Stanford Junior University
*
* Copying and distribution of this file, with or without modification, are
* permitted in any medium without royalty provided the copyright notice and
* this notice are preserved. This file is offered as-is, without any
* warranty.
*
* SPDX-License-Identifier: FSFAP
*/
#include <config.h>
#include <portable/macros.h>
#include <portable/socket.h>
#include <portable/system.h>
#include <errno.h>
/*
* If we're running the test suite, rename inet_ntoa to avoid conflicts with
* the system version. Note that we don't rename the structures and
* constants, but that should be okay (except possibly for gai_strerror).
*/
#if TESTING
# undef getnameinfo
# define getnameinfo test_getnameinfo
int test_getnameinfo(const struct sockaddr *, socklen_t, char *, socklen_t,
char *, socklen_t, int);
/* Linux doesn't provide EAI_OVERFLOW, so make up our own for testing. */
# ifndef EAI_OVERFLOW
# define EAI_OVERFLOW 10
# endif
#endif
/* Used for unused parameters to silence gcc warnings. */
#define UNUSED __attribute__((__unused__))
/*
* Check to see if a name is fully qualified by seeing if it contains a
* period. If it does, try to copy it into the provided node buffer and set
* status accordingly, returning true. If not, return false.
*/
static bool
try_name(const char *name, char *node, socklen_t nodelen, int *status)
{
size_t namelen;
if (strchr(name, '.') == NULL)
return false;
namelen = strlen(name);
if (namelen + 1 > (size_t) nodelen)
*status = EAI_OVERFLOW;
else {
memcpy(node, name, namelen + 1);
*status = 0;
}
return true;
}
/*
* Look up an address (or convert it to ASCII form) and put it in the provided
* buffer, depending on what is requested by flags.
*/
static int
lookup_name(const struct in_addr *addr, char *node, socklen_t nodelen,
int flags)
{
struct hostent *host;
char **alias;
int status;
char *name;
size_t namelen;
/* Do the name lookup first unless told not to. */
if (!(flags & NI_NUMERICHOST)) {
host = gethostbyaddr((const void *) addr, sizeof(struct in_addr),
AF_INET);
if (host == NULL) {
if (flags & NI_NAMEREQD)
return EAI_NONAME;
} else {
if (try_name(host->h_name, node, nodelen, &status))
return status;
for (alias = host->h_aliases; *alias != NULL; alias++)
if (try_name(*alias, node, nodelen, &status))
return status;
}
/*
* We found some results, but none of them were fully-qualified, so
* act as if we found nothing and either fail or fall through.
*/
if (flags & NI_NAMEREQD)
return EAI_NONAME;
}
/* Just convert the address to ASCII. */
name = inet_ntoa(*addr);
namelen = strlen(name);
if (namelen + 1 > (size_t) nodelen)
return EAI_OVERFLOW;
memcpy(node, name, namelen + 1);
return 0;
}
/*
* Look up a service (or convert it to ASCII form) and put it in the provided
* buffer, depending on what is requested by flags.
*/
static int
lookup_service(unsigned short port, char *service, socklen_t servicelen,
int flags)
{
struct servent *srv;
const char *protocol;
int status;
size_t namelen;
/* Do the name lookup first unless told not to. */
if (!(flags & NI_NUMERICSERV)) {
protocol = (flags & NI_DGRAM) ? "udp" : "tcp";
srv = getservbyport(htons(port), protocol);
if (srv != NULL) {
namelen = strlen(srv->s_name);
if (namelen + 1 > (size_t) servicelen)
return EAI_OVERFLOW;
memcpy(service, srv->s_name, namelen + 1);
return 0;
}
}
/* Just convert the port number to ASCII. */
status = snprintf(service, servicelen, "%hu", port);
if (status < 0 || (socklen_t) status >= servicelen)
return EAI_OVERFLOW;
return 0;
}
/*
* The getnameinfo implementation.
*/
int
getnameinfo(const struct sockaddr *sa, socklen_t salen UNUSED, char *node,
socklen_t nodelen, char *service, socklen_t servicelen, int flags)
{
const struct sockaddr_in *sin;
int status;
unsigned short port;
if ((node == NULL || nodelen <= 0) && (service == NULL || servicelen <= 0))
return EAI_NONAME;
/* We only support AF_INET. */
if (sa->sa_family != AF_INET)
return EAI_FAMILY;
sin = (const struct sockaddr_in *) (const void *) sa;
/* Name lookup. */
if (node != NULL && nodelen > 0) {
status = lookup_name(&sin->sin_addr, node, nodelen, flags);
if (status != 0)
return status;
}
/* Service lookup. */
if (service != NULL && servicelen > 0) {
port = ntohs(sin->sin_port);
return lookup_service(port, service, servicelen, flags);
} else
return 0;
}
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