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siproxd/src/utils.c
Thomas Ries 5b310dd9db - small enhancements in error checking
2004-06-13 20:48:57 +00:00

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/*
Copyright (C) 2002 Thomas Ries <tries@gmx.net>
This file is part of Siproxd.
Siproxd is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
Siproxd is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with Siproxd; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "config.h"
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <time.h>
#include <signal.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <net/if.h>
#include <sys/ioctl.h>
#ifdef _SOLARIS2
# include <sys/sockio.h>
#endif
#include <sys/types.h>
#include <pwd.h>
#include <osipparser2/osip_parser.h>
#include "siproxd.h"
#include "log.h"
static char const ident[]="$Id$";
/* configuration storage */
extern struct siproxd_config configuration;
extern int h_errno;
/*
* resolve a hostname and return in_addr
* handles its own little DNS cache.
*
* RETURNS
* STS_SUCCESS on success
* STS_FAILURE on failure
*/
int get_ip_by_host(char *hostname, struct in_addr *addr) {
int i, j;
time_t t;
struct hostent *hostentry;
#if defined(HAVE_GETHOSTBYNAME_R)
struct hostent result_buffer;
char tmp[GETHOSTBYNAME_BUFLEN];
#endif
int error;
static struct {
time_t timestamp;
struct in_addr addr;
char hostname[HOSTNAME_SIZE+1];
} dns_cache[DNS_CACHE_SIZE];
static int cache_initialized=0;
if (hostname == NULL) {
ERROR("get_ip_by_host: NULL hostname requested");
return STS_FAILURE;
}
if (addr == NULL) {
ERROR("get_ip_by_host: NULL in_addr passed");
return STS_FAILURE;
}
/* first time: initialize DNS cache */
if (cache_initialized == 0) {
DEBUGC(DBCLASS_DNS, "initializing DNS cache (%i entries)", DNS_CACHE_SIZE);
memset(dns_cache, 0, sizeof(dns_cache));
cache_initialized=1;
}
time(&t);
/* clean expired entries */
for (i=0; i<DNS_CACHE_SIZE; i++) {
if (dns_cache[i].hostname[0]=='\0') continue;
if ( (dns_cache[i].timestamp+DNS_MAX_AGE) < t ) {
DEBUGC(DBCLASS_DNS, "cleaning DNS cache (entry %i)", i);
memset (&dns_cache[i], 0, sizeof(dns_cache[0]));
}
}
/*
* search requested entry in cache
*/
for (i=0; i<DNS_CACHE_SIZE; i++) {
if (dns_cache[i].hostname[0]=='\0') continue; /* empty */
if (strcmp(hostname, dns_cache[i].hostname) == 0) { /* match */
memcpy(addr, &dns_cache[i].addr, sizeof(struct in_addr));
DEBUGC(DBCLASS_DNS, "DNS lookup - from cache: %s -> %s",
hostname, utils_inet_ntoa(*addr));
return STS_SUCCESS;
}
}
/* did not find it in cache, so I have to resolve it */
/* need to deal with reentrant versions of gethostbyname_r()
* as we may use threads... */
#if defined(HAVE_GETHOSTBYNAME_R)
/* gethostbyname_r() with 3 arguments (e.g. osf/1) */
#if defined(HAVE_FUNC_GETHOSTBYNAME_R_3)
gethostbyname_r(hostname, /* the FQDN */
&result_buffer, /* the result buffer */
&hostentry
);
if (hostentry == NULL) error = h_errno;
/* gethostbyname_r() with 5 arguments (e.g. solaris, linux libc5) */
#elif defined(HAVE_FUNC_GETHOSTBYNAME_R_5)
hostentry = gethostbyname_r(hostname, /* the FQDN */
&result_buffer, /* the result buffer */
tmp,
GETHOSTBYNAME_BUFLEN,
&error);
/* gethostbyname_r() with 6 arguments (e.g. linux glibc) */
#elif defined(HAVE_FUNC_GETHOSTBYNAME_R_6)
gethostbyname_r(hostname, /* the FQDN */
&result_buffer, /* the result buffer */
tmp,
GETHOSTBYNAME_BUFLEN,
&hostentry,
&error);
#else
#error "gethostbyname_r() with 3, 5 or 6 arguments supported only"
#endif
#elif defined(HAVE_GETHOSTBYNAME)
hostentry=gethostbyname(hostname);
if (hostentry == NULL) error = h_errno;
#else
#error "need gethostbyname() or gethostbyname_r()"
#endif
if (hostentry==NULL) {
/*
* Some errors just tell us that there was no IP resolvable.
* From the manpage:
* HOST_NOT_FOUND
* The specified host is unknown.
* HOST_NOT_FOUND
* The specified host is unknown.
* NO_ADDRESS or NO_DATA
* The requested name is valid but does not have an IP
* address.
*/
if ((error == HOST_NOT_FOUND) ||
(error == NO_ADDRESS) ||
(error == NO_DATA)) {
#ifdef HAVE_HSTRERROR
DEBUGC(DBCLASS_DNS, "gethostbyname(%s) failed: %s",
hostname, hstrerror(error));
#else
DEBUGC(DBCLASS_DNS, "gethostbyname(%s) failed: h_errno=%i",
hostname, error);
#endif
} else {
#ifdef HAVE_HSTRERROR
ERROR("gethostbyname(%s) failed: %s",hostname, hstrerror(h_errno));
#else
ERROR("gethostbyname(%s) failed: h_errno=%i",hostname, h_errno);
#endif
}
return STS_FAILURE;
}
memcpy(addr, hostentry->h_addr, sizeof(struct in_addr));
DEBUGC(DBCLASS_DNS, "DNS lookup - resolved: %s -> %s",
hostname, utils_inet_ntoa(*addr));
/*
* find an empty slot in the cache
*/
j=0;
for (i=0; i<DNS_CACHE_SIZE; i++) {
if (dns_cache[i].hostname[0]=='\0') break;
if (dns_cache[i].timestamp < t) {
/* remember oldest entry */
t=dns_cache[i].timestamp;
j=i;
}
}
/* if no empty slot found, take oldest one */
if (i >= DNS_CACHE_SIZE) i=j;
/*
* store the result in the cache
*/
DEBUGC(DBCLASS_DNS, "DNS lookup - store into cache, entry %i)", i);
memset(&dns_cache[i], 0, sizeof(dns_cache[0]));
strncpy(dns_cache[i].hostname, hostname, HOSTNAME_SIZE);
time(&dns_cache[i].timestamp);
memcpy(&dns_cache[i].addr, addr, sizeof(struct in_addr));
return STS_SUCCESS;
}
/*
* Secure enviroment:
* If running as root, put myself into a chroot jail and
* change UID/GID to user as requested in config file
*/
void secure_enviroment (void) {
int sts;
struct passwd *passwd=NULL;
DEBUGC(DBCLASS_CONFIG,"running w/uid=%i, euid=%i, gid=%i, egid=%i",
getuid(), geteuid(), getgid(), getegid());
if ((getuid()==0) || (geteuid()==0)) {
/*
* preparation - after chrooting there will be NOTHING more around
*/
if (configuration.user) passwd=getpwnam(configuration.user);
/*
* change root directory into chroot jail
*/
if (configuration.chrootjail) {
/* !!!
* Before chrooting I must at least once trigger the resolver
* as it loads some dynamic libraries. Once chrootet
* these libraries will *not* be found and gethostbyname()
* calls will simply fail (return NULL pointer and h_errno=0).
* Took me a while to figure THIS one out
*/
struct in_addr dummy;
DEBUGC(DBCLASS_DNS, "Initializing DNS, the following DNS "
"failure is normal, don't worry");
get_ip_by_host("foobar", &dummy);
DEBUGC(DBCLASS_CONFIG,"chrooting to %s",
configuration.chrootjail);
sts = chroot(configuration.chrootjail);
if (sts != 0) DEBUGC(DBCLASS_CONFIG,"chroot(%s) failed: %s",
configuration.chrootjail, strerror(errno));
chdir("/");
}
/*
* change user ID and group ID
*/
if (passwd) {
DEBUGC(DBCLASS_CONFIG,"changing uid/gid to %s",
configuration.user);
sts = setgid(passwd->pw_gid);
DEBUGC(DBCLASS_CONFIG,"changed gid to %i - %s",
passwd->pw_gid, (sts==0)?"Ok":"Failed");
sts = setegid(passwd->pw_uid);
DEBUGC(DBCLASS_CONFIG,"changed egid to %i - %s",
passwd->pw_gid, (sts==0)?"Ok":"Failed");
/* don't set the real user id - as we need to elevate privs
when setting up an RTP masquerading tunnel */
// sts = setuid(passwd->pw_uid);
// DEBUGC(DBCLASS_CONFIG,"changed uid to %i - %s",
// passwd->pw_uid, (sts==0)?"Ok":"Failed");
sts = seteuid(passwd->pw_uid);
DEBUGC(DBCLASS_CONFIG,"changed euid to %i - %s",
passwd->pw_uid, (sts==0)?"Ok":"Failed");
}
}
}
/*
* get_ip_by_ifname:
* fetches own IP address by its interface name
*
* STS_SUCCESS on returning a valid IP and interface is UP
* STS_FAILURE if interface is DOWN or other problem
*/
int get_ip_by_ifname(char *ifname, struct in_addr *retaddr) {
struct ifreq ifr;
struct sockaddr_in *sin = (struct sockaddr_in *)&ifr.ifr_addr;
int sockfd;
int i, j;
int ifflags, isup;
time_t t;
static struct {
time_t timestamp;
struct in_addr ifaddr; /* IP */
int isup; /* interface is UP */
char ifname[IFNAME_SIZE+1];
} ifaddr_cache[IFADR_CACHE_SIZE];
static int cache_initialized=0;
if (ifname == NULL) {
WARN("get_ip_by_ifname: got NULL ifname passed - please check config"
"file ('if_inbound' and 'if_outbound')");
return STS_FAILURE;
}
/* first time: initialize ifaddr cache */
if (cache_initialized == 0) {
DEBUGC(DBCLASS_DNS, "initializing ifaddr cache (%i entries)",
IFADR_CACHE_SIZE);
memset(ifaddr_cache, 0, sizeof(ifaddr_cache));
cache_initialized=1;
}
if (retaddr) memset(retaddr, 0, sizeof(struct in_addr));
time(&t);
/* clean expired entries */
for (i=0; i<IFADR_CACHE_SIZE; i++) {
if (ifaddr_cache[i].ifname[0]=='\0') continue;
if ( (ifaddr_cache[i].timestamp+IFADR_MAX_AGE) < t ) {
DEBUGC(DBCLASS_DNS, "cleaning ifaddr cache (entry %i)", i);
memset (&ifaddr_cache[i], 0, sizeof(ifaddr_cache[0]));
}
}
/*
* search requested entry in cache
*/
for (i=0; i<IFADR_CACHE_SIZE; i++) {
if (ifaddr_cache[i].ifname[0]=='\0') continue;
if (strcmp(ifname, ifaddr_cache[i].ifname) == 0) { /* match */
if (retaddr) memcpy(retaddr, &ifaddr_cache[i].ifaddr,
sizeof(struct in_addr));
DEBUGC(DBCLASS_DNS, "ifaddr lookup - from cache: %s -> %s %s",
ifname, utils_inet_ntoa(ifaddr_cache[i].ifaddr),
(ifaddr_cache[i].isup)? "UP":"DOWN");
return (ifaddr_cache[i].isup)? STS_SUCCESS: STS_FAILURE;
} /* if */
} /* for i */
/* not found in cache, go and get it */
memset(&ifr, 0, sizeof(ifr));
if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
ERROR("Error in socket: %s\n",strerror(errno));
return STS_FAILURE;
}
strcpy(ifr.ifr_name, ifname);
sin->sin_family = AF_INET;
/* get interface flags */
if(ioctl(sockfd, SIOCGIFFLAGS, &ifr) != 0) {
ERROR("Error in ioctl SIOCGIFFLAGS: %s [%s]\n",
strerror(errno), ifname);
close(sockfd);
return STS_FAILURE;
}
ifflags=ifr.ifr_flags;
/* get address */
if(ioctl(sockfd, SIOCGIFADDR, &ifr) != 0) {
ERROR("Error in ioctl SIOCGIFADDR: %s (interface %s)\n",
strerror(errno), ifname);
close(sockfd);
return STS_FAILURE;
}
if (ifflags & IFF_UP) isup=1;
else isup=0;
DEBUGC(DBCLASS_DNS, "get_ip_by_ifname: if %s has IP:%s (flags=%x) %s",
ifname, utils_inet_ntoa(sin->sin_addr), ifflags,
(isup)? "UP":"DOWN");
/*
*find an empty slot in the cache
*/
j=0;
for (i=0; i<IFADR_CACHE_SIZE; i++) {
if (ifaddr_cache[i].ifname[0]=='\0') break;
if (ifaddr_cache[i].timestamp < t) {
/* remember oldest entry */
t=ifaddr_cache[i].timestamp;
j=i;
}
}
/* if no empty slot found, take oldest one */
if (i >= IFADR_CACHE_SIZE) i=j;
/*
* store the result in the cache
*/
DEBUGC(DBCLASS_DNS, "ifname lookup - store into cache, entry %i)", i);
memset(&ifaddr_cache[i], 0, sizeof(ifaddr_cache[0]));
strncpy(ifaddr_cache[i].ifname, ifname, IFNAME_SIZE);
ifaddr_cache[i].timestamp=t;
memcpy(&ifaddr_cache[i].ifaddr, &sin->sin_addr, sizeof(sin->sin_addr));
ifaddr_cache[i].isup=isup;
if (retaddr) memcpy(retaddr, &sin->sin_addr, sizeof(sin->sin_addr));
close(sockfd);
return (isup)? STS_SUCCESS : STS_FAILURE;
}
/*
* utils_inet_ntoa:
* implements an inet_ntoa()
*
* Returns pointer to a static character string.
*/
char *utils_inet_ntoa(struct in_addr in) {
#if defined(HAVE_INET_NTOP)
static char string[INET_ADDRSTRLEN];
if ((inet_ntop(AF_INET, &in, string, INET_ADDRSTRLEN)) == NULL) {
ERROR("inet_ntop() failed: %s\n",strerror(errno));
string[0]='\0';
}
return string;
#elif defined(HAVE_INET_NTOA)
return inet_ntoa(in);
#else
#error "need inet_ntop() or inet_ntoa()"
#endif
}
/*
* utils_inet_aton:
* implements an inet_aton()
*
* converts the string in *cp and stores it into inp
* Returns != 0 on success
*/
int utils_inet_aton(const char *cp, struct in_addr *inp) {
#if defined(HAVE_INET_PTON)
return inet_pton (AF_INET, cp, inp);
#elif defined(HAVE_INET_ATON)
return inet_aton(cp, inp);
#else
#error "need inet_pton() or inet_aton()"
#endif
}
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