OpenBSD-4.6/libexec/tftpd/tftpd.c
/* $OpenBSD: tftpd.c,v 1.62 2008/03/24 16:11:00 deraadt Exp $ */
/*
* Copyright (c) 1983 Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1983 Regents of the University of California.\n\
All rights reserved.\n";
#endif /* not lint */
#ifndef lint
/*static char sccsid[] = "from: @(#)tftpd.c 5.13 (Berkeley) 2/26/91";*/
static char rcsid[] = "$OpenBSD: tftpd.c,v 1.62 2008/03/24 16:11:00 deraadt Exp $";
#endif /* not lint */
/*
* Trivial file transfer protocol server.
*
* This version includes many modifications by Jim Guyton <guyton@rand-unix>
*/
#include <sys/ioctl.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/uio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/tftp.h>
#include <netdb.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <poll.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <vis.h>
#define TIMEOUT 5 /* packet rexmt timeout */
#define TIMEOUT_MIN 1 /* minimal packet rexmt timeout */
#define TIMEOUT_MAX 255 /* maximal packet rexmt timeout */
struct formats;
int readit(FILE *, struct tftphdr **, int, int);
void read_ahead(FILE *, int, int);
int writeit(FILE *, struct tftphdr **, int, int);
int write_behind(FILE *, int);
int synchnet(int);
__dead void usage(void);
void tftp(struct tftphdr *, int);
int validate_access(char *, int);
int sendfile(struct formats *);
int recvfile(struct formats *);
void nak(int);
void oack(int);
static char *getip(struct sockaddr *);
FILE *file;
extern char *__progname;
struct sockaddr_storage s_in;
int peer;
int rexmtval = TIMEOUT;
int maxtimeout = 5 * TIMEOUT;
char *buf;
char *ackbuf;
struct sockaddr_storage from;
int ndirs;
char **dirs;
int secure;
int cancreate;
int logging;
unsigned int segment_size = SEGSIZE;
unsigned int packet_size = SEGSIZE + 4;
int has_options = 0;
struct formats {
const char *f_mode;
int (*f_validate)(char *, int);
int (*f_send)(struct formats *);
int (*f_recv)(struct formats *);
int f_convert;
} formats[] = {
{ "netascii", validate_access, sendfile, recvfile, 1 },
{ "octet", validate_access, sendfile, recvfile, 0 },
{ NULL, NULL, NULL, NULL, 0 }
};
struct options {
const char *o_type;
char *o_request;
long long o_reply; /* turn into union if need be */
} options[] = {
{ "tsize", NULL, 0 }, /* OPT_TSIZE */
{ "timeout", NULL, 0 }, /* OPT_TIMEOUT */
{ "blksize", NULL, 0 }, /* OPT_BLKSIZE */
{ NULL, NULL, 0 }
};
enum opt_enum {
OPT_TSIZE = 0,
OPT_TIMEOUT,
OPT_BLKSIZE
};
struct errmsg {
int e_code;
const char *e_msg;
} errmsgs[] = {
{ EUNDEF, "Undefined error code" },
{ ENOTFOUND, "File not found" },
{ EACCESS, "Access violation" },
{ ENOSPACE, "Disk full or allocation exceeded" },
{ EBADOP, "Illegal TFTP operation" },
{ EBADID, "Unknown transfer ID" },
{ EEXISTS, "File already exists" },
{ ENOUSER, "No such user" },
{ EOPTNEG, "Option negotiation failed" },
{ -1, NULL }
};
__dead void
usage(void)
{
syslog(LOG_ERR, "usage: %s [-cl] [directory ...]", __progname);
syslog(LOG_ERR, "usage: %s [-cl] -s directory", __progname);
exit(1);
}
int
main(int argc, char *argv[])
{
int n = 0, on = 1, fd = 0, i, c, dobind = 1;
struct tftphdr *tp;
struct passwd *pw;
union {
struct cmsghdr hdr;
char buf[CMSG_SPACE(sizeof(struct sockaddr_storage))];
} cmsgbuf;
struct cmsghdr *cmsg;
struct msghdr msg;
struct iovec iov;
pid_t pid = 0;
socklen_t j;
openlog(__progname, LOG_PID|LOG_NDELAY, LOG_DAEMON);
while ((c = getopt(argc, argv, "cls")) != -1) {
switch (c) {
case 'c':
cancreate = 1;
break;
case 'l':
logging = 1;
break;
case 's':
secure = 1;
break;
default:
usage();
/* NOTREACHED */
}
}
for (; optind != argc; optind++) {
char **d;
d = realloc(dirs, (ndirs + 2) * sizeof(char *));
if (d == NULL) {
syslog(LOG_ERR, "realloc: %m");
exit(1);
}
dirs = d;
dirs[n++] = argv[optind];
dirs[n] = NULL;
ndirs++;
}
pw = getpwnam("_tftpd");
if (pw == NULL) {
syslog(LOG_ERR, "no _tftpd: %m");
exit(1);
}
if (secure) {
if (ndirs == 0) {
syslog(LOG_ERR, "no -s directory");
exit(1);
}
if (ndirs > 1) {
syslog(LOG_ERR, "too many -s directories");
exit(1);
}
tzset();
if (chroot(dirs[0])) {
syslog(LOG_ERR, "chroot %s: %m", dirs[0]);
exit(1);
}
if (chdir("/")) {
syslog(LOG_ERR, "chdir: %m");
exit(1);
}
}
setegid(pw->pw_gid);
setgid(pw->pw_gid);
seteuid(pw->pw_uid);
setuid(pw->pw_uid);
if (ioctl(fd, FIONBIO, &on) < 0) {
syslog(LOG_ERR, "ioctl(FIONBIO): %m");
exit(1);
}
j = sizeof(s_in);
if (getsockname(fd, (struct sockaddr *)&s_in, &j) == -1) {
syslog(LOG_ERR, "getsockname: %m");
exit(1);
}
switch (s_in.ss_family) {
case AF_INET:
if (setsockopt(fd, IPPROTO_IP, IP_RECVDSTADDR, &on,
sizeof(on)) == -1) {
syslog(LOG_ERR, "setsockopt(IP_RECVDSTADDR): %m");
exit (1);
}
break;
case AF_INET6:
if (setsockopt(fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &on,
sizeof(on)) == -1) {
syslog(LOG_ERR, "setsockopt(IPV6_RECVPKTINFO): %m");
exit (1);
}
break;
}
if ((buf = malloc(SEGSIZE_MAX + 4)) == NULL) {
syslog(LOG_ERR, "malloc: %m");
exit(1);
}
if ((ackbuf = malloc(SEGSIZE_MAX + 4)) == NULL) {
syslog(LOG_ERR, "malloc: %m");
exit(1);
}
bzero(&msg, sizeof(msg));
iov.iov_base = buf;
iov.iov_len = packet_size;
msg.msg_name = &from;
msg.msg_namelen = sizeof(from);
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_control = &cmsgbuf.buf;
msg.msg_controllen = sizeof(cmsgbuf.buf);
n = recvmsg(fd, &msg, 0);
if (n < 0) {
syslog(LOG_ERR, "recvmsg: %m");
exit(1);
}
/*
* Now that we have read the message out of the UDP
* socket, we fork and exit. Thus, inetd will go back
* to listening to the tftp port, and the next request
* to come in will start up a new instance of tftpd.
*
* We do this so that inetd can run tftpd in "wait" mode.
* The problem with tftpd running in "nowait" mode is that
* inetd may get one or more successful "selects" on the
* tftp port before we do our receive, so more than one
* instance of tftpd may be started up. Worse, if tftpd
* breaks before doing the above "recvfrom", inetd would
* spawn endless instances, clogging the system.
*/
for (i = 1; i < 20; i++) {
pid = fork();
if (pid < 0) {
sleep(i);
/*
* Flush out to most recently sent request.
*
* This may drop some requests, but those
* will be resent by the clients when
* they timeout. The positive effect of
* this flush is to (try to) prevent more
* than one tftpd being started up to service
* a single request from a single client.
*/
bzero(&msg, sizeof(msg));
iov.iov_base = buf;
iov.iov_len = packet_size;
msg.msg_name = &from;
msg.msg_namelen = sizeof(from);
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_control = &cmsgbuf.buf;
msg.msg_controllen = sizeof(cmsgbuf.buf);
i = recvmsg(fd, &msg, 0);
if (i > 0)
n = i;
} else
break;
}
if (pid < 0) {
syslog(LOG_ERR, "fork: %m");
exit(1);
} else if (pid != 0)
exit(0);
alarm(0);
close(fd);
close(1);
peer = socket(from.ss_family, SOCK_DGRAM, 0);
if (peer < 0) {
syslog(LOG_ERR, "socket: %m");
exit(1);
}
memset(&s_in, 0, sizeof(s_in));
s_in.ss_family = from.ss_family;
s_in.ss_len = from.ss_len;
/* get local address if possible */
for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
cmsg = CMSG_NXTHDR(&msg, cmsg)) {
if (cmsg->cmsg_level == IPPROTO_IP &&
cmsg->cmsg_type == IP_RECVDSTADDR) {
memcpy(&((struct sockaddr_in *)&s_in)->sin_addr,
CMSG_DATA(cmsg), sizeof(struct in_addr));
if (((struct sockaddr_in *)&s_in)->sin_addr.s_addr ==
INADDR_BROADCAST)
dobind = 0;
break;
}
if (cmsg->cmsg_level == IPPROTO_IPV6 &&
cmsg->cmsg_type == IPV6_PKTINFO) {
struct in6_pktinfo *ipi;
ipi = (struct in6_pktinfo *)CMSG_DATA(cmsg);
memcpy(&((struct sockaddr_in6 *)&s_in)->sin6_addr,
&ipi->ipi6_addr, sizeof(struct in6_addr));
#ifdef __KAME__
if (IN6_IS_ADDR_LINKLOCAL(&ipi->ipi6_addr))
((struct sockaddr_in6 *)&s_in)->sin6_scope_id =
ipi->ipi6_ifindex;
#endif
break;
}
}
if (dobind) {
(void) setsockopt(peer, SOL_SOCKET, SO_REUSEADDR, &on,
sizeof(on));
(void) setsockopt(peer, SOL_SOCKET, SO_REUSEPORT, &on,
sizeof(on));
if (bind(peer, (struct sockaddr *)&s_in, s_in.ss_len) < 0) {
syslog(LOG_ERR, "bind to %s: %m",
inet_ntoa(((struct sockaddr_in *)&s_in)->sin_addr));
exit(1);
}
}
if (connect(peer, (struct sockaddr *)&from, from.ss_len) < 0) {
syslog(LOG_ERR, "connect: %m");
exit(1);
}
tp = (struct tftphdr *)buf;
tp->th_opcode = ntohs(tp->th_opcode);
if (tp->th_opcode == RRQ || tp->th_opcode == WRQ)
tftp(tp, n);
exit(1);
}
/*
* Handle initial connection protocol.
*/
void
tftp(struct tftphdr *tp, int size)
{
char *cp;
int i, first = 1, ecode, opcode, to;
struct formats *pf;
char *filename, *mode = NULL, *option, *ccp;
char fnbuf[MAXPATHLEN], nicebuf[MAXPATHLEN];
const char *errstr;
cp = tp->th_stuff;
again:
while (cp < buf + size) {
if (*cp == '\0')
break;
cp++;
}
if (*cp != '\0') {
nak(EBADOP);
exit(1);
}
i = cp - tp->th_stuff;
if (i >= sizeof(fnbuf)) {
nak(EBADOP);
exit(1);
}
memcpy(fnbuf, tp->th_stuff, i);
fnbuf[i] = '\0';
filename = fnbuf;
if (first) {
mode = ++cp;
first = 0;
goto again;
}
for (cp = mode; *cp; cp++)
if (isupper(*cp))
*cp = tolower(*cp);
for (pf = formats; pf->f_mode; pf++)
if (strcmp(pf->f_mode, mode) == 0)
break;
if (pf->f_mode == 0) {
nak(EBADOP);
exit(1);
}
while (++cp < buf + size) {
for (i = 2, ccp = cp; i > 0; ccp++) {
if (ccp >= buf + size) {
/*
* Don't reject the request, just stop trying
* to parse the option and get on with it.
* Some Apple OpenFirmware versions have
* trailing garbage on the end of otherwise
* valid requests.
*/
goto option_fail;
} else if (*ccp == '\0')
i--;
}
for (option = cp; *cp; cp++)
if (isupper(*cp))
*cp = tolower(*cp);
for (i = 0; options[i].o_type != NULL; i++)
if (strcmp(option, options[i].o_type) == 0) {
options[i].o_request = ++cp;
has_options = 1;
}
cp = ccp - 1;
}
option_fail:
if (options[OPT_TIMEOUT].o_request) {
to = strtonum(options[OPT_TIMEOUT].o_request,
TIMEOUT_MIN, TIMEOUT_MAX, &errstr);
if (errstr) {
nak(EBADOP);
exit(1);
}
options[OPT_TIMEOUT].o_reply = rexmtval = to;
}
if (options[OPT_BLKSIZE].o_request) {
segment_size = strtonum(options[OPT_BLKSIZE].o_request,
SEGSIZE_MIN, SEGSIZE_MAX, &errstr);
if (errstr) {
nak(EBADOP);
exit(1);
}
packet_size = segment_size + 4;
options[OPT_BLKSIZE].o_reply = segment_size;
}
/* save opcode before it gets overwritten by oack() */
opcode = tp->th_opcode;
(void)strnvis(nicebuf, filename, MAXPATHLEN, VIS_SAFE|VIS_OCTAL);
ecode = (*pf->f_validate)(filename, opcode);
if (logging)
syslog(LOG_INFO, "%s: %s request for '%s'",
getip((struct sockaddr *)&from),
opcode == WRQ ? "write" : "read",
nicebuf);
if (has_options)
oack(opcode);
if (ecode) {
syslog(LOG_INFO, "%s: denied %s access to '%s'",
getip((struct sockaddr *)&from),
opcode == WRQ ? "write" : "read", nicebuf);
nak(ecode);
exit(1);
}
if (opcode == WRQ)
(*pf->f_recv)(pf);
else
(*pf->f_send)(pf);
exit(0);
}
/*
* Validate file access. Since we
* have no uid or gid, for now require
* file to exist and be publicly
* readable/writable.
* If we were invoked with arguments
* from inetd then the file must also be
* in one of the given directory prefixes.
* Note also, full path name must be
* given as we have no login directory.
*/
int
validate_access(char *filename, int mode)
{
struct stat stbuf;
char *cp, **dirp;
int fd, wmode;
const char *errstr;
if (!secure) {
if (*filename != '/')
return (EACCESS);
/*
* Prevent tricksters from getting around the directory
* restrictions.
*/
for (cp = filename + 1; *cp; cp++)
if (*cp == '.' && strncmp(cp - 1, "/../", 4) == 0)
return (EACCESS);
for (dirp = dirs; *dirp; dirp++)
if (strncmp(filename, *dirp, strlen(*dirp)) == 0)
break;
if (*dirp == 0 && dirp != dirs)
return (EACCESS);
}
/*
* We use a different permissions scheme if `cancreate' is
* set.
*/
wmode = O_TRUNC;
if (stat(filename, &stbuf) < 0) {
if (!cancreate)
return (errno == ENOENT ? ENOTFOUND : EACCESS);
else {
if ((errno == ENOENT) && (mode != RRQ))
wmode |= O_CREAT;
else
return (EACCESS);
}
} else {
if (mode == RRQ) {
if ((stbuf.st_mode & (S_IREAD >> 6)) == 0)
return (EACCESS);
} else {
if ((stbuf.st_mode & (S_IWRITE >> 6)) == 0)
return (EACCESS);
}
}
if (options[OPT_TSIZE].o_request) {
if (mode == RRQ)
options[OPT_TSIZE].o_reply = stbuf.st_size;
else {
/* allows writes of 65535 blocks * SEGSIZE_MAX bytes */
options[OPT_TSIZE].o_reply =
strtonum(options[OPT_TSIZE].o_request,
1, 65535LL * SEGSIZE_MAX, &errstr);
if (errstr) {
nak(EOPTNEG);
exit(1);
}
}
}
fd = open(filename, mode == RRQ ? O_RDONLY : (O_WRONLY|wmode), 0666);
if (fd < 0)
return (errno + 100);
/*
* If the file was created, set default permissions.
*/
if ((wmode & O_CREAT) && fchmod(fd, 0666) < 0) {
int serrno = errno;
close(fd);
unlink(filename);
return (serrno + 100);
}
file = fdopen(fd, mode == RRQ ? "r" : "w");
if (file == NULL) {
close(fd);
return (errno + 100);
}
return (0);
}
/*
* Send the requested file.
*/
int
sendfile(struct formats *pf)
{
struct tftphdr *dp, *r_init(void);
struct tftphdr *ap; /* ack packet */
struct pollfd pfd[1];
volatile unsigned short block = 1;
int n, size, nfds, error, timeouts;
dp = r_init();
ap = (struct tftphdr *)ackbuf;
do {
/* read data from file */
size = readit(file, &dp, pf->f_convert, segment_size);
if (size < 0) {
nak(errno + 100);
goto abort;
}
dp->th_opcode = htons((u_short)DATA);
dp->th_block = htons((u_short)block);
/* send data to client and wait for client ACK */
for (timeouts = 0, error = 0;;) {
if (timeouts >= maxtimeout)
exit(1);
if (!error) {
if (send(peer, dp, size + 4, 0) != size + 4) {
syslog(LOG_ERR, "send: %m");
goto abort;
}
read_ahead(file, pf->f_convert, segment_size);
}
error = 0;
pfd[0].fd = peer;
pfd[0].events = POLLIN;
nfds = poll(pfd, 1, rexmtval * 1000);
if (nfds == 0) {
timeouts += rexmtval;
continue;
}
if (nfds == -1) {
error = 1;
if (errno == EINTR)
continue;
syslog(LOG_ERR, "poll: %m");
goto abort;
}
n = recv(peer, ackbuf, packet_size, 0);
if (n == -1) {
error = 1;
if (errno == EINTR)
continue;
syslog(LOG_ERR, "recv: %m");
goto abort;
}
ap->th_opcode = ntohs((u_short)ap->th_opcode);
ap->th_block = ntohs((u_short)ap->th_block);
if (ap->th_opcode == ERROR)
goto abort;
if (ap->th_opcode == ACK) {
if (ap->th_block == block)
break;
/* re-synchronize with the other side */
(void)synchnet(peer);
if (ap->th_block == (block - 1))
continue;
}
error = 1; /* FALLTHROUGH */
}
block++;
} while (size == segment_size);
abort:
fclose(file);
return (1);
}
/*
* Receive a file.
*/
int
recvfile(struct formats *pf)
{
struct tftphdr *dp, *w_init(void);
struct tftphdr *ap; /* ack buffer */
struct pollfd pfd[1];
volatile unsigned short block = 0;
int n, size, nfds, error, timeouts;
dp = w_init();
ap = (struct tftphdr *)ackbuf;
/* if we have options, do not send a first ACK */
if (has_options) {
block++;
goto noack;
}
do {
/* create new ACK packet */
ap->th_opcode = htons((u_short)ACK);
ap->th_block = htons((u_short)block);
block++;
/* send ACK to client and wait for client data */
for (timeouts = 0, error = 0;;) {
if (timeouts >= maxtimeout)
exit(1);
if (!error) {
if (send(peer, ackbuf, 4, 0) != 4) {
syslog(LOG_ERR, "send: %m");
goto abort;
}
write_behind(file, pf->f_convert);
}
error = 0;
pfd[0].fd = peer;
pfd[0].events = POLLIN;
nfds = poll(pfd, 1, rexmtval * 1000);
if (nfds == 0) {
timeouts += rexmtval;
continue;
}
if (nfds == -1) {
error = 1;
if (errno == EINTR)
continue;
syslog(LOG_ERR, "poll: %m");
goto abort;
}
noack:
n = recv(peer, dp, packet_size, 0);
if (n == -1) {
error = 1;
if (errno == EINTR)
continue;
syslog(LOG_ERR, "recv: %m");
goto abort;
}
dp->th_opcode = ntohs((u_short)dp->th_opcode);
dp->th_block = ntohs((u_short)dp->th_block);
if (dp->th_opcode == ERROR)
goto abort;
if (dp->th_opcode == DATA) {
if (dp->th_block == block)
break;
/* re-synchronize with the other side */
(void)synchnet(peer);
if (dp->th_block == (block - 1))
continue;
}
error = 1; /* FALLTHROUGH */
}
/* write data to file */
size = writeit(file, &dp, n - 4, pf->f_convert);
if (size != (n - 4)) {
if (size < 0)
nak(errno + 100);
else
nak(ENOSPACE);
goto abort;
}
} while (size == segment_size);
/* close data file */
write_behind(file, pf->f_convert);
(void)fclose(file);
/* send final ack */
ap->th_opcode = htons((u_short)ACK);
ap->th_block = htons((u_short)(block));
(void)send(peer, ackbuf, 4, 0);
/* just quit on timeout */
pfd[0].fd = peer;
pfd[0].events = POLLIN;
nfds = poll(pfd, 1, rexmtval * 1000);
if (nfds < 1)
exit(1);
n = recv(peer, buf, packet_size, 0);
/*
* If read some data and got a data block then my last ack was lost
* resend final ack.
*/
if (n >= 4 && dp->th_opcode == DATA && block == dp->th_block)
(void)send(peer, ackbuf, 4, 0);
abort:
return (1);
}
/*
* Send a nak packet (error message).
* Error code passed in is one of the
* standard TFTP codes, or a UNIX errno
* offset by 100.
*/
void
nak(int error)
{
struct tftphdr *tp;
struct errmsg *pe;
int length;
tp = (struct tftphdr *)buf;
tp->th_opcode = htons((u_short)ERROR);
tp->th_code = htons((u_short)error);
for (pe = errmsgs; pe->e_code >= 0; pe++)
if (pe->e_code == error)
break;
if (pe->e_code < 0) {
pe->e_msg = strerror(error - 100);
tp->th_code = EUNDEF; /* set 'undef' errorcode */
}
length = strlcpy(tp->th_msg, pe->e_msg, packet_size) + 5;
if (length > packet_size)
length = packet_size;
if (send(peer, buf, length, 0) != length)
syslog(LOG_ERR, "nak: %m");
}
/*
* Send an oack packet (option acknowledgement).
*/
void
oack(int opcode)
{
struct tftphdr *tp, *ap;
struct pollfd pfd[1];
char *bp;
int i, n, size, nfds, error, timeouts;
tp = (struct tftphdr *)buf;
bp = buf + 2;
size = packet_size - 2;
tp->th_opcode = htons((u_short)OACK);
for (i = 0; options[i].o_type != NULL; i++) {
if (options[i].o_request) {
n = snprintf(bp, size, "%s%c%lld", options[i].o_type,
0, options[i].o_reply);
if (n == -1 || n >= size) {
syslog(LOG_ERR, "oack: no buffer space");
exit(1);
}
bp += n + 1;
size -= n + 1;
if (size < 0) {
syslog(LOG_ERR, "oack: no buffer space");
exit(1);
}
}
}
size = bp - buf;
ap = (struct tftphdr *)ackbuf;
/* send OACK to client and wait for client ACK */
for (timeouts = 0, error = 0;;) {
if (timeouts >= maxtimeout)
exit(1);
if (!error) {
if (send(peer, buf, size, 0) != size) {
syslog(LOG_INFO, "oack: %m");
exit(1);
}
}
error = 0;
pfd[0].fd = peer;
pfd[0].events = POLLIN;
nfds = poll(pfd, 1, rexmtval * 1000);
if (nfds == 0) {
timeouts += rexmtval;
continue;
}
if (nfds == -1) {
error = 1;
if (errno == EINTR)
continue;
syslog(LOG_ERR, "poll: %m");
exit(1);
}
/* no client ACK for write requests with options */
if (opcode == WRQ)
break;
n = recv(peer, ackbuf, packet_size, 0);
if (n == -1) {
error = 1;
if (errno == EINTR)
continue;
syslog(LOG_ERR, "recv: %m");
exit(1);
}
ap->th_opcode = ntohs((u_short)ap->th_opcode);
ap->th_block = ntohs((u_short)ap->th_block);
if (ap->th_opcode == ERROR)
exit(1);
if (ap->th_opcode == ACK && ap->th_block == 0)
break;
error = 1; /* FALLTHROUGH */
}
}
static char *
getip(struct sockaddr *sa)
{
static char hbuf[NI_MAXHOST];
if (getnameinfo(sa, sa->sa_len, hbuf, sizeof(hbuf), NULL, 0, NI_NUMERICHOST))
strlcpy(hbuf, "0.0.0.0", sizeof(hbuf));
return(hbuf);
}