Add TFTP options windowsize (RFC 7440) and timeout (RFC 2349).

This commit is contained in:
Simon Kelley
2025-05-24 09:09:39 +01:00
parent 1861a881eb
commit ebef27f321
5 changed files with 277 additions and 184 deletions

View File

@@ -59,6 +59,8 @@ version 2.92
Fix failure to cache PTR RRs when a reply contains more than one answer.
Thanks to Dmitry for spotting this.
Add TFTP options windowsize (RFC 7440) and timeout (RFC 2349).
version 2.91
Fix spurious "resource limit exceeded messages". Thanks to

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@@ -52,6 +52,8 @@
#define CHUSER "nobody"
#define CHGRP "dip"
#define TFTP_MAX_CONNECTIONS 50 /* max simultaneous connections */
#define TFTP_MAX_WINDOW 32 /* max window size to negotiate */
#define TFTP_TRANSFER_TIME 120 /* Abandon TFTP transfers after this long. Two mins. */
#define LOG_MAX 5 /* log-queue length */
#define RANDFILE "/dev/urandom"
#define DNSMASQ_SERVICE "uk.org.thekelleys.dnsmasq" /* Default - may be overridden by config */

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@@ -30,7 +30,9 @@ static volatile pid_t pid = 0;
static volatile int pipewrite;
static void set_dns_listeners(void);
#ifdef HAVE_TFTP
static void set_tftp_listeners(void);
#endif
static void check_dns_listeners(time_t now);
static void do_tcp_connection(struct listener *listener, time_t now, int slot);
static void sig_handler(int sig);

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@@ -1117,14 +1117,13 @@ struct tftp_file {
struct tftp_transfer {
int sockfd;
time_t timeout;
int backoff;
unsigned int block, blocksize, expansion;
time_t retransmit, start;
unsigned int lastack, block, blocksize, windowsize, timeout, expansion;
off_t offset;
union mysockaddr peer;
union all_addr source;
int if_index;
char opt_blocksize, opt_transize, netascii, carrylf;
unsigned char opt_blocksize, opt_transize, opt_windowsize, opt_timeout, netascii, carrylf, backoff;
struct tftp_file *file;
struct tftp_transfer *next;
};
@@ -1768,7 +1767,6 @@ void queue_relay_snoop(struct in6_addr *client, int if_index, struct in6_addr *p
/* tftp.c */
#ifdef HAVE_TFTP
void tftp_request(struct listener *listen, time_t now);
void check_tftp_listeners(time_t now);
int do_tftp_script_run(void);
#endif

View File

@@ -41,11 +41,11 @@ static void sanitise(char *buf);
#define ERR_ILL 4
#define ERR_TID 5
void tftp_request(struct listener *listen, time_t now)
static void tftp_request(struct listener *listen, time_t now)
{
ssize_t len;
char *packet = daemon->packet;
char *filename, *mode, *p, *end, *opt;
char *filename, *mode, *p, *end;
union mysockaddr addr, peer;
struct msghdr msg;
struct iovec iov;
@@ -309,6 +309,8 @@ void tftp_request(struct listener *listen, time_t now)
if (!transfer && !(transfer = whine_malloc(sizeof(struct tftp_transfer))))
return;
memset(transfer, 0, sizeof(struct tftp_transfer));
if (option_bool(OPT_SINGLE_PORT))
transfer->sockfd = listen->tftpfd;
else if ((transfer->sockfd = socket(family, SOCK_DGRAM, 0)) == -1)
@@ -320,14 +322,12 @@ void tftp_request(struct listener *listen, time_t now)
transfer->peer = peer;
transfer->source = addra;
transfer->if_index = if_index;
transfer->timeout = now + 2;
transfer->timeout = 2;
transfer->start = now;
transfer->backoff = 1;
transfer->block = 1;
transfer->blocksize = 512;
transfer->offset = 0;
transfer->file = NULL;
transfer->opt_blocksize = transfer->opt_transize = 0;
transfer->netascii = transfer->carrylf = 0;
transfer->windowsize = 1;
(void)prettyprint_addr(&peer, daemon->addrbuff);
@@ -362,139 +362,166 @@ void tftp_request(struct listener *listen, time_t now)
p = packet + 2;
end = packet + len;
if (!(filename = next(&p, end)) ||
!(mode = next(&p, end)) ||
(strcasecmp(mode, "octet") != 0 && strcasecmp(mode, "netascii") != 0) ||
ntohs(*((unsigned short *)packet)) != OP_RRQ)
{
if (!filename)
len = tftp_err(ERR_ILL, packet, _("empty filename in request from %s"), daemon->addrbuff, NULL);
else
len = tftp_err(ERR_ILL, packet, _("unsupported %srequest from %s"),
(ntohs(*((unsigned short *)packet)) == OP_WRQ) ? _("write ") : "", daemon->addrbuff);
is_err = 1;
}
else
{
if (strcasecmp(mode, "netascii") == 0)
transfer->netascii = 1;
len = 0;
while ((opt = next(&p, end)))
if (ntohs(*((unsigned short *)packet)) == OP_WRQ)
len = tftp_err(ERR_ILL, packet, _("unsupported write request from %s"),daemon->addrbuff, NULL);
else if (ntohs(*((unsigned short *)packet)) == OP_RRQ)
{
if (!(filename = next(&p, end)))
len = tftp_err(ERR_ILL, packet, _("empty filename in request from %s"), daemon->addrbuff, NULL);
else if (!(mode = next(&p, end)) || (strcasecmp(mode, "octet") != 0 && strcasecmp(mode, "netascii") != 0))
len = tftp_err(ERR_ILL, packet, _("unsupported request from %s"),daemon->addrbuff, NULL);
else
{
if (strcasecmp(opt, "blksize") == 0)
char *opt, *arg;
if (strcasecmp(mode, "netascii") == 0)
transfer->netascii = 1;
while ((opt = next(&p, end)) && (arg = next(&p, end)))
{
if ((opt = next(&p, end)) && !option_bool(OPT_TFTP_NOBLOCK))
unsigned int val = atoi(arg);
if (strcasecmp(opt, "blksize") == 0 && !option_bool(OPT_TFTP_NOBLOCK))
{
/* 32 bytes for IP, UDP and TFTP headers, 52 bytes for IPv6 */
int overhead = (family == AF_INET) ? 32 : 52;
transfer->blocksize = atoi(opt);
if (transfer->blocksize < 1)
transfer->blocksize = 1;
if (transfer->blocksize > (unsigned)daemon->packet_buff_sz - 4)
transfer->blocksize = (unsigned)daemon->packet_buff_sz - 4;
if (mtu != 0 && transfer->blocksize > (unsigned)mtu - overhead)
transfer->blocksize = (unsigned)mtu - overhead;
if (val < 1)
val = 1;
if (val > (unsigned)daemon->packet_buff_sz - 4)
val = (unsigned)daemon->packet_buff_sz - 4;
if (mtu != 0 && val > (unsigned)mtu - overhead)
val = (unsigned)mtu - overhead;
transfer->blocksize = val;
transfer->opt_blocksize = 1;
transfer->block = 0;
}
}
else if (strcasecmp(opt, "tsize") == 0 && next(&p, end) && !transfer->netascii)
{
transfer->opt_transize = 1;
transfer->block = 0;
}
}
/* cope with backslashes from windows boxen. */
for (p = filename; *p; p++)
if (*p == '\\')
*p = '/';
else if (option_bool(OPT_TFTP_LC))
*p = tolower((unsigned char)*p);
strcpy(daemon->namebuff, "/");
if (prefix)
{
if (prefix[0] == '/')
daemon->namebuff[0] = 0;
strncat(daemon->namebuff, prefix, (MAXDNAME-1) - strlen(daemon->namebuff));
if (prefix[strlen(prefix)-1] != '/')
strncat(daemon->namebuff, "/", (MAXDNAME-1) - strlen(daemon->namebuff));
if (option_bool(OPT_TFTP_APREF_IP))
{
size_t oldlen = strlen(daemon->namebuff);
struct stat statbuf;
strncat(daemon->namebuff, daemon->addrbuff, (MAXDNAME-1) - strlen(daemon->namebuff));
strncat(daemon->namebuff, "/", (MAXDNAME-1) - strlen(daemon->namebuff));
/* remove unique-directory if it doesn't exist */
if (stat(daemon->namebuff, &statbuf) == -1 || !S_ISDIR(statbuf.st_mode))
daemon->namebuff[oldlen] = 0;
}
if (option_bool(OPT_TFTP_APREF_MAC))
{
unsigned char *macaddr = NULL;
unsigned char macbuf[DHCP_CHADDR_MAX];
#ifdef HAVE_DHCP
if (daemon->dhcp && peer.sa.sa_family == AF_INET)
{
/* Check if the client IP is in our lease database */
struct dhcp_lease *lease = lease_find_by_addr(peer.in.sin_addr);
if (lease && lease->hwaddr_type == ARPHRD_ETHER && lease->hwaddr_len == ETHER_ADDR_LEN)
macaddr = lease->hwaddr;
else if (strcasecmp(opt, "tsize") == 0 && !transfer->netascii)
{
transfer->opt_transize = 1;
transfer->block = 0;
}
#endif
else if (strcasecmp(opt, "timeout") == 0)
{
if (val > 255)
val = 255;
transfer->timeout = val;
transfer->opt_timeout = 1;
transfer->block = 0;
}
else if (strcasecmp(opt, "windowsize") == 0 && !transfer->netascii)
{
/* windowsize option only supported for binary transfers. */
if (val < 1)
val = 1;
if (val > TFTP_MAX_WINDOW)
val = TFTP_MAX_WINDOW;
transfer->windowsize = val;
transfer->opt_windowsize = 1;
transfer->block = 0;
}
}
/* If no luck, try to find in ARP table. This only works if client is in same (V)LAN */
if (!macaddr && find_mac(&peer, macbuf, 1, now) > 0)
macaddr = macbuf;
/* cope with backslashes from windows boxen. */
for (p = filename; *p; p++)
if (*p == '\\')
*p = '/';
else if (option_bool(OPT_TFTP_LC))
*p = tolower((unsigned char)*p);
if (macaddr)
{
strcpy(daemon->namebuff, "/");
if (prefix)
{
if (prefix[0] == '/')
daemon->namebuff[0] = 0;
strncat(daemon->namebuff, prefix, (MAXDNAME-1) - strlen(daemon->namebuff));
if (prefix[strlen(prefix)-1] != '/')
strncat(daemon->namebuff, "/", (MAXDNAME-1) - strlen(daemon->namebuff));
if (option_bool(OPT_TFTP_APREF_IP))
{
size_t oldlen = strlen(daemon->namebuff);
struct stat statbuf;
snprintf(daemon->namebuff + oldlen, (MAXDNAME-1) - oldlen, "%.2x-%.2x-%.2x-%.2x-%.2x-%.2x/",
macaddr[0], macaddr[1], macaddr[2], macaddr[3], macaddr[4], macaddr[5]);
strncat(daemon->namebuff, daemon->addrbuff, (MAXDNAME-1) - strlen(daemon->namebuff));
strncat(daemon->namebuff, "/", (MAXDNAME-1) - strlen(daemon->namebuff));
/* remove unique-directory if it doesn't exist */
if (stat(daemon->namebuff, &statbuf) == -1 || !S_ISDIR(statbuf.st_mode))
daemon->namebuff[oldlen] = 0;
}
}
/* Absolute pathnames OK if they match prefix */
if (filename[0] == '/')
if (option_bool(OPT_TFTP_APREF_MAC))
{
unsigned char *macaddr = NULL;
unsigned char macbuf[DHCP_CHADDR_MAX];
#ifdef HAVE_DHCP
if (daemon->dhcp && peer.sa.sa_family == AF_INET)
{
/* Check if the client IP is in our lease database */
struct dhcp_lease *lease = lease_find_by_addr(peer.in.sin_addr);
if (lease && lease->hwaddr_type == ARPHRD_ETHER && lease->hwaddr_len == ETHER_ADDR_LEN)
macaddr = lease->hwaddr;
}
#endif
/* If no luck, try to find in ARP table. This only works if client is in same (V)LAN */
if (!macaddr && find_mac(&peer, macbuf, 1, now) > 0)
macaddr = macbuf;
if (macaddr)
{
size_t oldlen = strlen(daemon->namebuff);
struct stat statbuf;
snprintf(daemon->namebuff + oldlen, (MAXDNAME-1) - oldlen, "%.2x-%.2x-%.2x-%.2x-%.2x-%.2x/",
macaddr[0], macaddr[1], macaddr[2], macaddr[3], macaddr[4], macaddr[5]);
/* remove unique-directory if it doesn't exist */
if (stat(daemon->namebuff, &statbuf) == -1 || !S_ISDIR(statbuf.st_mode))
daemon->namebuff[oldlen] = 0;
}
}
/* Absolute pathnames OK if they match prefix */
if (filename[0] == '/')
{
if (strstr(filename, daemon->namebuff) == filename)
daemon->namebuff[0] = 0;
else
filename++;
}
}
else if (filename[0] == '/')
daemon->namebuff[0] = 0;
strncat(daemon->namebuff, filename, (MAXDNAME-1) - strlen(daemon->namebuff));
/* check permissions and open file */
if ((transfer->file = check_tftp_fileperm(&len, prefix, daemon->addrbuff)))
{
if (strstr(filename, daemon->namebuff) == filename)
daemon->namebuff[0] = 0;
transfer->lastack = transfer->block;
transfer->retransmit = now + transfer->timeout;
/* This packet is may be the first data packet, but only if windowsize == 1
To get windowsize greater then one requires an option negotiation,
in which case this packet is the OACK. */
if ((len = get_block(packet, transfer)) == -1)
len = tftp_err_oops(packet, daemon->namebuff);
else
filename++;
is_err = 0;
}
}
else if (filename[0] == '/')
daemon->namebuff[0] = 0;
strncat(daemon->namebuff, filename, (MAXDNAME-1) - strlen(daemon->namebuff));
/* check permissions and open file */
if ((transfer->file = check_tftp_fileperm(&len, prefix, daemon->addrbuff)))
{
if ((len = get_block(packet, transfer)) == -1)
len = tftp_err_oops(packet, daemon->namebuff);
else
is_err = 0;
}
}
send_from(transfer->sockfd, !option_bool(OPT_SINGLE_PORT), packet, len, &peer, &addra, if_index);
if (len)
{
send_from(transfer->sockfd, !option_bool(OPT_SINGLE_PORT), packet, len, &peer, &addra, if_index);
#ifdef HAVE_DUMPFILE
dump_packet_udp(DUMP_TFTP, (void *)packet, len, NULL, (union mysockaddr *)&peer, transfer->sockfd);
dump_packet_udp(DUMP_TFTP, (void *)packet, len, NULL, (union mysockaddr *)&peer, transfer->sockfd);
#endif
}
if (is_err)
free_transfer(transfer);
@@ -610,6 +637,10 @@ void check_tftp_listeners(time_t now)
if ((len = recvfrom(transfer->sockfd, daemon->packet, daemon->packet_buff_sz, 0, &peer.sa, &addr_len)) > 0)
{
#ifdef HAVE_DUMPFILE
dump_packet_udp(DUMP_TFTP, (void *)daemon->packet, len, (union mysockaddr *)&peer, NULL, transfer->sockfd);
#endif
if (sockaddr_isequal(&peer, &transfer->peer))
handle_tftp(now, transfer, len);
else
@@ -628,63 +659,91 @@ void check_tftp_listeners(time_t now)
for (transfer = daemon->tftp_trans, up = &daemon->tftp_trans; transfer; transfer = tmp)
{
int endcon = 0, error = 0, timeout = 0;
tmp = transfer->next;
if (difftime(now, transfer->timeout) >= 0.0)
/* ->start set to zero in handle_tftp() when we recv an error packet. */
if (transfer->start == 0)
endcon = error = 1;
else if (difftime(now, transfer->start) > TFTP_TRANSFER_TIME)
{
int endcon = 0;
endcon = 1;
/* don't complain about timeout when we're awaiting the last
ACK, some clients never send it */
if (get_block(daemon->packet, transfer) > 0)
error = timeout = 1;
}
else if (difftime(now, transfer->retransmit) >= 0.0)
{
/* Do transmission or re-transmission. When we get an ACK, the call to handle_tftp()
bumps transfer->lastack and trips the retransmit timer so that we send the next block(s)
here. */
unsigned int i, winsize;
ssize_t len;
/* timeout, retransmit */
transfer->timeout += 1 + (1<<(transfer->backoff/2));
transfer->retransmit += transfer->timeout + (1<<(transfer->backoff/2));
transfer->backoff++;
transfer->block = transfer->lastack;
/* we overwrote the buffer... */
daemon->srv_save = NULL;
if ((len = get_block(daemon->packet, transfer)) == 0)
endcon = 1; /* got last ACK */
else
{
/* send a window'a worth of blocks unless we're retransmitting OACK */
winsize = transfer->block ? transfer->windowsize : 1;
if ((len = get_block(daemon->packet, transfer)) == -1)
{
len = tftp_err_oops(daemon->packet, transfer->file->filename);
endcon = 1;
}
else if (++transfer->backoff > 7)
{
/* don't complain about timeout when we're awaiting the last
ACK, some clients never send it */
if ((unsigned)len == transfer->blocksize + 4)
endcon = 1;
len = 0;
}
/* we overwrote the buffer... */
daemon->srv_save = NULL;
if (len != 0)
{
send_from(transfer->sockfd, !option_bool(OPT_SINGLE_PORT), daemon->packet, len,
&transfer->peer, &transfer->source, transfer->if_index);
#ifdef HAVE_DUMPFILE
dump_packet_udp(DUMP_TFTP, (void *)daemon->packet, len, NULL, (union mysockaddr *)&transfer->peer, transfer->sockfd);
#endif
}
if (endcon || len == 0)
{
strcpy(daemon->namebuff, transfer->file->filename);
sanitise(daemon->namebuff);
(void)prettyprint_addr(&transfer->peer, daemon->addrbuff);
my_syslog(MS_TFTP | LOG_INFO, endcon ? _("failed sending %s to %s") : _("sent %s to %s"), daemon->namebuff, daemon->addrbuff);
/* unlink */
*up = tmp;
if (endcon)
free_transfer(transfer);
else
for (i = 0; i < winsize && !endcon; i++, transfer->block++)
{
/* put on queue to be sent to script and deleted */
transfer->next = daemon->tftp_done_trans;
daemon->tftp_done_trans = transfer;
if (i != 0)
len = get_block(daemon->packet, transfer);
if (len == 0)
break;
if (len == -1)
{
len = tftp_err_oops(daemon->packet, transfer->file->filename);
endcon = error = 1;
}
send_from(transfer->sockfd, !option_bool(OPT_SINGLE_PORT), daemon->packet, len,
&transfer->peer, &transfer->source, transfer->if_index);
#ifdef HAVE_DUMPFILE
dump_packet_udp(DUMP_TFTP, (void *)daemon->packet, len, NULL, (union mysockaddr *)&transfer->peer, transfer->sockfd);
#endif
}
continue;
}
}
up = &transfer->next;
if (endcon)
{
strcpy(daemon->namebuff, transfer->file->filename);
sanitise(daemon->namebuff);
(void)prettyprint_addr(&transfer->peer, daemon->addrbuff);
if (timeout)
my_syslog(MS_TFTP | LOG_ERR, _("timeout sending %s to %s"), daemon->namebuff, daemon->addrbuff);
else if (error)
my_syslog(MS_TFTP | LOG_ERR, _("failed sending %s to %s"), daemon->namebuff, daemon->addrbuff);
else
my_syslog(MS_TFTP | LOG_INFO, _("sent %s to %s"), daemon->namebuff, daemon->addrbuff);
/* unlink */
*up = tmp;
if (error)
free_transfer(transfer);
else
{
/* put on queue to be sent to script and deleted */
transfer->next = daemon->tftp_done_trans;
daemon->tftp_done_trans = transfer;
}
}
else
up = &transfer->next;
}
}
@@ -697,13 +756,30 @@ static void handle_tftp(time_t now, struct tftp_transfer *transfer, ssize_t len)
if (len >= (ssize_t)sizeof(struct ack))
{
if (ntohs(mess->op) == OP_ACK && ntohs(mess->block) == (unsigned short)transfer->block)
if (ntohs(mess->op) == OP_ACK)
{
/* Got ack, ensure we take the (re)transmit path */
transfer->timeout = now;
transfer->backoff = 0;
if (transfer->block++ != 0)
transfer->offset += transfer->blocksize - transfer->expansion;
/* try and handle 16-bit blockno wrap-around */
unsigned int block = (unsigned short)ntohs(mess->block);
if (block < transfer->lastack)
block |= transfer->block & 0xffff0000;
/* ignore duplicate ACKs and ACKs for blocks we've not yet sent. */
if (block >= transfer->lastack &&
block <= transfer->block)
{
/* Got ack, move forward and ensure we take the (re)transmit path */
transfer->retransmit = transfer->start = now;
transfer->backoff = 0;
transfer->lastack = block + 1;
/* We have no easy function from block no. to file offset when
expanding line breaks in netascii mode, so we update the offset here
as each block is acknowledged. This explains why the window size must be
one for a netascii transfer; to avoid the block no. doing anything
other than incrementing by one. */
if (transfer->netascii && block != 0)
transfer->offset += transfer->blocksize - transfer->expansion;
}
}
else if (ntohs(mess->op) == OP_ERR)
{
@@ -724,8 +800,7 @@ static void handle_tftp(time_t now, struct tftp_transfer *transfer, ssize_t len)
daemon->addrbuff);
/* Got err, ensure we take abort */
transfer->timeout = now;
transfer->backoff = 100;
transfer->start = 0;
}
}
}
@@ -835,6 +910,16 @@ static ssize_t get_block(char *packet, struct tftp_transfer *transfer)
p += (sprintf(p,"tsize") + 1);
p += (sprintf(p, "%u", (unsigned int)transfer->file->size) + 1);
}
if (transfer->opt_timeout)
{
p += (sprintf(p,"timeout") + 1);
p += (sprintf(p, "%u", transfer->timeout) + 1);
}
if (transfer->opt_windowsize)
{
p += (sprintf(p,"windowsize") + 1);
p += (sprintf(p, "%u", (unsigned int)transfer->windowsize) + 1);
}
return p - packet;
}
@@ -846,31 +931,35 @@ static ssize_t get_block(char *packet, struct tftp_transfer *transfer)
unsigned char data[];
} *mess = (struct datamess *)packet;
size_t size = transfer->file->size - transfer->offset;
size_t size;
if (!transfer->netascii)
transfer->offset = (transfer->block - 1) * transfer->blocksize;
if (transfer->offset > transfer->file->size)
return 0; /* finished */
if (size > transfer->blocksize)
if ((size = transfer->file->size - transfer->offset) > transfer->blocksize)
size = transfer->blocksize;
mess->op = htons(OP_DATA);
mess->block = htons((unsigned short)(transfer->block));
if (lseek(transfer->file->fd, transfer->offset, SEEK_SET) == (off_t)-1 ||
!read_write(transfer->file->fd, mess->data, size, RW_READ))
if (size != 0 &&
(lseek(transfer->file->fd, transfer->offset, SEEK_SET) == (off_t)-1 ||
!read_write(transfer->file->fd, mess->data, size, RW_READ)))
return -1;
transfer->expansion = 0;
/* Map '\n' to CR-LF in netascii mode */
if (transfer->netascii)
{
size_t i;
int newcarrylf;
transfer->expansion = 0;
for (i = 0, newcarrylf = 0; i < size; i++)
if (mess->data[i] == '\n' && ( i != 0 || !transfer->carrylf))
if (mess->data[i] == '\n' && (i != 0 || !transfer->carrylf))
{
transfer->expansion++;
@@ -885,8 +974,8 @@ static ssize_t get_block(char *packet, struct tftp_transfer *transfer)
i++;
}
transfer->carrylf = newcarrylf;
transfer->carrylf = newcarrylf;
}
return size + 4;