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#include <unistd.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdio.h>
#include <syslog.h>
#include <string.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <netdb.h>
#include <pthread.h>
#include <sys/types.h>
#include <sys/time.h>
#include <pwd.h>
#include <grp.h>
#include <errno.h>
#include <signal.h>
#include "packet.h"
#include "netascii.h"
#include "handlers.h"
int nbtpd_stop = 0;
void stop_handler(int i) {
syslog(LOG_ERR, "caught shutdown signal, cleaning up.");
if (i != 0) {
nbtpd_stop = i;
} else {
nbtpd_stop = 1;
}
return;
}
void usage(char *name) {
printf("USAGE: %s -d -u nobody -g nobody -a 127.0.0.1 -p 69\n", name);
printf("\td: daemonize.\n");
printf("\tu: username to run as (default: nobody). Must be specified after -d.\n");
printf("\tg: group to run as (default: nobody). Must be specified after -d.\n");
printf("\ta: address to bind to (default: 127.0.0.1)\n");
printf("\tp: port to bind to (default: 69)\n");
}
int main(int argc, char **argv) {
int daemonize = 0;
char addr[16], user[32], group[32];
memset(addr, '\0', sizeof(addr));
memset(user, '\0', sizeof(user));
memset(group, '\0', sizeof(group));
strcpy(addr, "127.0.0.1");
strcpy(user, "nobody");
strcpy(group, "nobody");
int port = 69;
int ch = 0;
while ((ch = getopt(argc, argv, "da:p:u:g:h")) != -1) {
switch (ch) {
case 'a':
//TODO: this is unsafe
strcpy(addr, optarg);
break;
case 'p':
port = atoi(optarg);
if ((port <= 0) || (port >= 65536)) {
fprintf(stderr, "invalid port specified.\n");
return -1;
}
break;
case 'd':
daemonize = 1;
break;
case 'g':
if (daemonize) {
//TODO: this is unsafe
strcpy(group, optarg);
} else {
fprintf(stderr, "-g requires -d\n");
return -1;
}
break;
case 'u':
if (daemonize) {
//TODO: this is unsafe
strcpy(user, optarg);
} else {
fprintf(stderr, "-u requires -d\n");
return -1;
}
break;
case 'h': case '?':
usage(argv[0]);
return -1;
}
}
setlogmask(LOG_UPTO(LOG_INFO));
openlog(argv[0], LOG_PID | LOG_PERROR | LOG_NDELAY, LOG_FTP);
syslog(LOG_INFO, "starting up...");
signal(SIGTERM, &stop_handler);
signal(SIGINT, &stop_handler);
if (daemonize) {
if (daemon(1, 0)) {
syslog(LOG_ERR, "failed to daemonize as requested!");
return -1;
} else {
syslog(LOG_INFO, "daemonized");
}
}
int s = socket(AF_INET, SOCK_DGRAM, 0);
if (s <= 0) {
syslog(LOG_ERR, "unable to bind socket!");
return -1;
}
struct timeval timeout = { 1, 0 };
if (setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout)) < 0) {
syslog(LOG_ERR, "unable to set socket timeout: %s", strerror(errno));
close(s);
return -1;
}
struct sockaddr_in saddr;
saddr.sin_family = AF_INET;
saddr.sin_port = htons(port);
saddr.sin_addr.s_addr = inet_addr(addr);
if (bind(s, (struct sockaddr*)&saddr, sizeof(saddr)) < 0) {
syslog(LOG_ERR, "socket bind failed: %s", strerror(errno));
return -1;
}
syslog(LOG_INFO, "socket bind success");
if (daemonize) {
//TODO: use getpwnam_r() and getgrnam_r()
struct group *g = getgrnam((const char *)&group);
if (setgid((*g).gr_gid) == -1) {
syslog(LOG_ERR, "failed to drop group privileges");
return -1;
}
struct passwd *u = getpwnam((const char *)&user);
if (setuid((*u).pw_uid) == -1) {
syslog(LOG_ERR, "failed to drop user privileges");
return -1;
}
}
// create persistent buffer
char *buf;
buf = malloc(1024);
if (buf == NULL) {
syslog(LOG_CRIT, "unable to allocate memory!");
close(s);
return -1;
}
while (!nbtpd_stop) {
struct sockaddr_in caddr;
unsigned int clen = sizeof(caddr);
memset(buf, '\0', 1024);
ssize_t recvd_bytes = 0;
if ((recvd_bytes = recvfrom(s, buf, 1024, 0,
(struct sockaddr *)&caddr, &clen)) < 0) {
continue;
}
if (recvd_bytes < 4) {
syslog(LOG_ERR, "ignoring invalid packet.");
continue;
}
nbd_nbtpd_args *args = malloc(sizeof(nbd_nbtpd_args));
if (args == NULL) {
syslog(LOG_CRIT, "unable to allocate memory");
continue;
}
nbd_tftp_opcode oc = ntohs(((uint16_t)buf[0] << 8) + buf[1]);
(*args).client = caddr;
(*args).err = 0;
memset((*args).path, '\0', 768);
memset((*args).mode, '\0', 32);
int i;
for(i = 2; buf[i] != 0 && i < recvd_bytes && (i - 2) < 768; i++) {
(*args).path[i - 2] = buf[i];
}
int s = i + 1;
if (s >= recvd_bytes) {
oc = 0;
} else {
for(i = s; buf[i] != 0 && i < recvd_bytes && (i - s) < 32; i++) {
(*args).mode[i - s] = buf[i];
}
}
pthread_t *_thread = malloc(sizeof(pthread_t));
if (_thread == NULL) {
syslog(LOG_CRIT, "unable to allocate memory");
free(args);
continue;
}
void *(*func)(void *);
switch (oc) {
case RRQ:
func = &read_req_resp;
break;
case WRQ:
func = &write_req_resp;
break;
default:
(*args).err = 4;
func = &nbd_nbtpd_resp_error;
}
if (pthread_create(_thread, 0, func, (void *)args) != 0) {
syslog(
LOG_CRIT,
"unable to handle request: cannot create thread!"
);
free(args);
}
}
// free our persistent buffer
free(buf);
// close socket
close(s);
// wait for threads to exit
pthread_exit(NULL);
// exit program
return 0;
}
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