mirrors
/
sudo
mirror of https://github.com/sudo-project/sudo.git
0
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity
sudo/lib/util/getaddrinfo.c

407 lines
12 KiB
C
Raw Permalink Blame History

/*
* Replacement for a missing getaddrinfo.
*
* This is an implementation of getaddrinfo for systems that don't have one so
* that networking code can use a consistent interface without #ifdef. It is
* a fairly minimal implementation, with the following limitations:
*
* - IPv4 support only. IPv6 is not supported.
* - AI_ADDRCONFIG is ignored.
* - Not thread-safe due to gethostbyname and getservbyname.
* - SOCK_DGRAM and SOCK_STREAM only.
* - Multiple possible socket types only generate one addrinfo struct.
* - Protocol hints aren't used correctly.
*
* The last four issues could probably be easily remedied, but haven't been
* needed to date. Adding IPv6 support isn't worth it; systems with IPv6
* support should already have getaddrinfo.
*
* The canonical version of this file is maintained in the rra-c-util package,
* which can be found at <http://www.eyrie.org/~eagle/software/rra-c-util/>.
*
* Written by Russ Allbery <rra@stanford.edu>
*
* The authors hereby relinquish any claim to any copyright that they may have
* in this work, whether granted under contract or by operation of law or
* international treaty, and hereby commit to the public, at large, that they
* shall not, at any time in the future, seek to enforce any copyright in this
* work against any person or entity, or prevent any person or entity from
* copying, publishing, distributing or creating derivative works of this
* work.
*/
#include <config.h>
#ifndef HAVE_GETADDRINFO
#include <sys/types.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <netdb.h>
#include <errno.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#ifdef NEED_RESOLV_H
# include <arpa/nameser.h>
# include <resolv.h>
#endif /* NEED_RESOLV_H */
#include <sudo_compat.h>
#include <compat/getaddrinfo.h>
/* We need access to h_errno to map errors from gethostbyname. */
#ifndef HAVE_DECL_H_ERRNO
extern int h_errno;
#endif
/*
* The netdb constants, which aren't always defined (particularly if h_errno
* isn't declared). We also make sure that a few of the less-used ones are
* defined so that we can deal with them in case statements.
*/
#ifndef HOST_NOT_FOUND
# define HOST_NOT_FOUND 1
# define TRY_AGAIN 2
# define NO_RECOVERY 3
# define NO_DATA 4
#endif
#ifndef NETDB_INTERNAL
# define NETDB_INTERNAL -1
#endif
/*
* If we're running the test suite, rename the functions 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).
*/
#ifdef TESTING
# define gai_strerror test_gai_strerror
# define freeaddrinfo test_freeaddrinfo
# define getaddrinfo test_getaddrinfo
const char *test_gai_strerror(int);
void test_freeaddrinfo(struct addrinfo *);
int test_getaddrinfo(const char *, const char *, const struct addrinfo *,
struct addrinfo **);
#endif
/*
* If the platform doesn't support AI_NUMERICSERV or AI_NUMERICHOST,
* pick some other values for them.
*/
#ifdef TESTING
# if AI_NUMERICSERV == 0
# undef AI_NUMERICSERV
# define AI_NUMERICSERV 0x0080
# endif
# if AI_NUMERICHOST == 0
# undef AI_NUMERICHOST
# define AI_NUMERICHOST 0x0100
# endif
#endif
/*
* Value representing all of the hint flags set. Linux uses flags up to
* 0x0400, so be sure not to break when testing on that platform.
*/
#ifdef TESTING
# ifdef HAVE_GETADDRINFO
# define AI_INTERNAL_ALL 0x04ff
# else
# define AI_INTERNAL_ALL 0x01ff
# endif
#else
# define AI_INTERNAL_ALL 0x007f
#endif
/* Table of strings corresponding to the EAI_* error codes. */
static const char * const gai_errors[] = {
"Host name lookup failure", /* 1 EAI_AGAIN */
"Invalid flag value", /* 2 EAI_BADFLAGS */
"Unknown server error", /* 3 EAI_FAIL */
"Unsupported address family", /* 4 EAI_FAMILY */
"Memory allocation failure", /* 5 EAI_MEMORY */
"Host unknown or not given", /* 6 EAI_NONAME */
"Service not supported for socket", /* 7 EAI_SERVICE */
"Unsupported socket type", /* 8 EAI_SOCKTYPE */
"System error", /* 9 EAI_SYSTEM */
"Supplied buffer too small", /* 10 EAI_OVERFLOW */
};
/* Macro to set the len attribute of sockaddr_in. */
#ifdef HAVE_STRUCT_SOCKADDR_IN_SIN_LEN
# define sin_set_length(s) ((s)->sin_len = sizeof(struct sockaddr_in))
#else
# define sin_set_length(s) /* empty */
#endif
/*
* Return a constant string for a given EAI_* error code or a string
* indicating an unknown error.
*/
const char *
sudo_gai_strerror(int ecode)
{
if (ecode < 1 || (size_t) ecode > nitems(gai_errors))
return "Unknown error";
else
return gai_errors[ecode - 1];
}
/*
* Free a linked list of addrinfo structs.
*/
void
sudo_freeaddrinfo(struct addrinfo *ai)
{
struct addrinfo *next;
while (ai != NULL) {
next = ai->ai_next;
if (ai->ai_addr != NULL)
free(ai->ai_addr);
if (ai->ai_canonname != NULL)
free(ai->ai_canonname);
free(ai);
ai = next;
}
}
/*
* Allocate a new addrinfo struct, setting some defaults given that this
* implementation is IPv4 only. Also allocates an attached sockaddr_in and
* zeroes it, per the requirement for getaddrinfo. Takes the socktype,
* canonical name (which is copied if not NULL), address, and port. Returns
* NULL on a memory allocation failure.
*/
static struct addrinfo *
gai_addrinfo_new(int socktype, const char *canonical, struct in_addr addr,
unsigned short port)
{
struct addrinfo *ai;
ai = malloc(sizeof(*ai));
if (ai == NULL)
return NULL;
ai->ai_addr = malloc(sizeof(struct sockaddr_in));
if (ai->ai_addr == NULL) {
free(ai);
return NULL;
}
ai->ai_next = NULL;
if (canonical == NULL)
ai->ai_canonname = NULL;
else {
ai->ai_canonname = strdup(canonical);
if (ai->ai_canonname == NULL) {
freeaddrinfo(ai);
return NULL;
}
}
memset(ai->ai_addr, 0, sizeof(struct sockaddr_in));
ai->ai_flags = 0;
ai->ai_family = AF_INET;
ai->ai_socktype = socktype;
ai->ai_protocol = (socktype == SOCK_DGRAM) ? IPPROTO_UDP : IPPROTO_TCP;
ai->ai_addrlen = sizeof(struct sockaddr_in);
((struct sockaddr_in *) ai->ai_addr)->sin_family = AF_INET;
((struct sockaddr_in *) ai->ai_addr)->sin_addr = addr;
((struct sockaddr_in *) ai->ai_addr)->sin_port = htons(port);
sin_set_length((struct sockaddr_in *) ai->ai_addr);
return ai;
}
/*
* Look up a service. Takes the service name (which may be numeric), the hint
* flags, a pointer to the socket type (used to determine whether TCP or UDP
* services are of interest and, if 0, is filled in with the result of
* getservbyname if the service was not numeric), and a pointer to the
* addrinfo struct to fill in. Returns 0 on success or an EAI_* error on
* failure.
*/
static int
gai_service(const char *servname, int flags, int *type, unsigned short *port)
{
struct servent *servent;
const char *protocol;
const char *errstr;
unsigned short value;
value = sudo_strtonum(servname, 0, USHRT_MAX, &errstr);
if (errstr == NULL) {
*port = value;
} else if (errno == ERANGE) {
return EAI_SERVICE;
} else {
if (flags & AI_NUMERICSERV)
return EAI_NONAME;
if (*type != 0)
protocol = (*type == SOCK_DGRAM) ? "udp" : "tcp";
else
protocol = NULL;
/*
* We really technically should be generating an addrinfo struct for
* each possible protocol unless type is set, but this works well
* enough for what I need this for.
*/
servent = getservbyname(servname, protocol);
if (servent == NULL)
return EAI_NONAME;
if (strcmp(servent->s_proto, "udp") == 0)
*type = SOCK_DGRAM;
else if (strcmp(servent->s_proto, "tcp") == 0)
*type = SOCK_STREAM;
else
return EAI_SERVICE;
*port = htons(servent->s_port);
}
return 0;
}
/*
* Look up a host and fill in a linked list of addrinfo structs with the
* results, one per IP address of the returned host. Takes the name or IP
* address of the host as a string, the lookup flags, the type of socket (to
* fill into the addrinfo structs), the port (likewise), and a pointer to
* where the head of the linked list should be put. Returns 0 on success or
* the appropriate EAI_* error.
*/
static int
gai_lookup(const char *nodename, int flags, int socktype, unsigned short port,
struct addrinfo **res)
{
struct addrinfo *ai, *first, *prev;
struct in_addr addr;
struct hostent *host;
const char *canonical;
size_t i;
if (inet_pton(AF_INET, nodename, &addr)) {
canonical = (flags & AI_CANONNAME) ? nodename : NULL;
ai = gai_addrinfo_new(socktype, canonical, addr, port);
if (ai == NULL)
return EAI_MEMORY;
*res = ai;
return 0;
} else {
if (flags & AI_NUMERICHOST)
return EAI_NONAME;
host = gethostbyname(nodename);
if (host == NULL)
switch (h_errno) {
case HOST_NOT_FOUND:
return EAI_NONAME;
case TRY_AGAIN:
case NO_DATA:
return EAI_AGAIN;
case NO_RECOVERY:
return EAI_FAIL;
case NETDB_INTERNAL:
default:
return EAI_SYSTEM;
}
if (host->h_addr_list[0] == NULL)
return EAI_FAIL;
canonical = (flags & AI_CANONNAME)
? ((host->h_name != NULL) ? host->h_name : nodename)
: NULL;
first = NULL;
prev = NULL;
for (i = 0; host->h_addr_list[i] != NULL; i++) {
if (host->h_length != sizeof(addr)) {
freeaddrinfo(first);
return EAI_FAIL;
}
memcpy(&addr, host->h_addr_list[i], sizeof(addr));
ai = gai_addrinfo_new(socktype, canonical, addr, port);
if (ai == NULL) {
freeaddrinfo(first);
return EAI_MEMORY;
}
if (first == NULL) {
first = ai;
prev = ai;
} else {
prev->ai_next = ai;
prev = ai;
}
}
*res = first;
return 0;
}
}
/*
* The actual getaddrinfo implementation.
*/
int
sudo_getaddrinfo(const char *nodename, const char *servname,
const struct addrinfo *hints, struct addrinfo **res)
{
struct addrinfo *ai;
struct in_addr addr;
int flags, socktype, status;
unsigned short port;
/* Take the hints into account and check them for validity. */
if (hints != NULL) {
flags = hints->ai_flags;
socktype = hints->ai_socktype;
if ((flags & AI_INTERNAL_ALL) != flags)
return EAI_BADFLAGS;
if (hints->ai_family != AF_UNSPEC && hints->ai_family != AF_INET)
return EAI_FAMILY;
if (socktype != 0 && socktype != SOCK_STREAM && socktype != SOCK_DGRAM)
return EAI_SOCKTYPE;
/* EAI_SOCKTYPE isn't quite right, but there isn't anything better. */
if (hints->ai_protocol != 0) {
int protocol = hints->ai_protocol;
if (protocol != IPPROTO_TCP && protocol != IPPROTO_UDP)
return EAI_SOCKTYPE;
}
} else {
flags = 0;
socktype = 0;
}
/*
* See what we're doing. If nodename is null, either AI_PASSIVE is set or
* we're getting information for connecting to a service on the loopback
* address. Otherwise, we're getting information for connecting to a
* remote system.
*/
if (servname == NULL)
port = 0;
else {
status = gai_service(servname, flags, &socktype, &port);
if (status != 0)
return status;
}
if (nodename != NULL)
return gai_lookup(nodename, flags, socktype, port, res);
else {
if (servname == NULL)
return EAI_NONAME;
if ((flags & AI_PASSIVE) == AI_PASSIVE)
addr.s_addr = INADDR_ANY;
else
addr.s_addr = htonl(0x7f000001UL);
ai = gai_addrinfo_new(socktype, NULL, addr, port);
if (ai == NULL)
return EAI_MEMORY;
*res = ai;
return 0;
}
}
#endif /* HAVE_GETADDRINFO */
Reference in New Issue View Git Blame Copy Permalink