static int
alias_pna_out(struct libalias *la, struct ip *pip,
struct alias_link *lnk,
char *data,
int dlen)
{
struct alias_link *pna_links;
u_short msg_id, msg_len;
char *work;
u_short alias_port, port;
struct tcphdr *tc;
work = data;
work += 5;
while (work + 4 < data + dlen) {
memcpy(&msg_id, work, 2);
work += 2;
memcpy(&msg_len, work, 2);
work += 2;
if (ntohs(msg_id) == 0) {
/* end of options */
return (0);
}
if ((ntohs(msg_id) == 1) || (ntohs(msg_id) == 7)) {
memcpy(&port, work, 2);
pna_links = FindUdpTcpOut(la, pip->ip_src, GetDestAddress(lnk),
port, 0, IPPROTO_UDP, 1);
if (pna_links != NULL) {
#ifndef NO_FW_PUNCH
/* Punch hole in firewall */
PunchFWHole(pna_links);
#endif
tc = (struct tcphdr *)ip_next(pip);
alias_port = GetAliasPort(pna_links);
memcpy(work, &alias_port, 2);
/* Compute TCP checksum for revised packet */
tc->th_sum = 0;
#ifdef _KERNEL
tc->th_x2 = 1;
#else
tc->th_sum = TcpChecksum(pip);
#endif
}
}
work += ntohs(msg_len);
}
return (0);
}
static void
AliasHandleCUSeeMeOut(struct libalias *la, struct ip *pip, struct alias_link *lnk)
{
struct udphdr *ud = ip_next(pip);
if (ntohs(ud->uh_ulen) - sizeof(struct udphdr) >= sizeof(struct cu_header)) {
struct cu_header *cu;
struct alias_link *cu_lnk;
cu = udp_next(ud);
if (cu->addr)
cu->addr = (u_int32_t) GetAliasAddress(lnk).s_addr;
cu_lnk = FindUdpTcpOut(la, pip->ip_src, GetDestAddress(lnk),
ud->uh_dport, 0, IPPROTO_UDP, 1);
#ifndef NO_FW_PUNCH
if (cu_lnk)
PunchFWHole(cu_lnk);
#endif
}
}
void
AliasHandleCUSeeMeOut(struct ip *pip, struct alias_link *link)
{
struct udphdr *ud;
ud = (struct udphdr *)((char *)pip + (pip->ip_hl << 2));
if (ntohs(ud->uh_ulen) - sizeof(struct udphdr) >= sizeof(struct cu_header)) {
struct cu_header *cu;
struct alias_link *cu_link;
cu = (struct cu_header *)(ud + 1);
if (cu->addr)
cu->addr = (u_int32_t)GetAliasAddress(link).s_addr;
cu_link = FindUdpTcpOut(pip->ip_src, GetDestAddress(link),
ud->uh_dport, 0, IPPROTO_UDP, 1);
#ifndef NO_FW_PUNCH
if (cu_link)
PunchFWHole(cu_link);
#endif
}
}
static int
alias_rtsp_out(struct libalias *la, struct ip *pip,
struct alias_link *lnk,
char *data,
const char *port_str)
{
int hlen, tlen, dlen;
struct tcphdr *tc;
int i, j, pos, state, port_dlen, new_dlen, delta;
u_short p[2], new_len;
u_short sport, eport, base_port;
u_short salias = 0, ealias = 0, base_alias = 0;
const char *transport_str = "transport:";
char newdata[2048], *port_data, *port_newdata, stemp[80];
int links_created = 0, pkt_updated = 0;
struct alias_link *rtsp_lnk = NULL;
struct in_addr null_addr;
/* Calculate data length of TCP packet */
tc = (struct tcphdr *)ip_next(pip);
hlen = (pip->ip_hl + tc->th_off) << 2;
tlen = ntohs(pip->ip_len);
dlen = tlen - hlen;
/* Find keyword, "Transport: " */
pos = search_string(data, dlen, transport_str);
if (pos < 0) {
return (-1);
}
port_data = data + pos;
port_dlen = dlen - pos;
memcpy(newdata, data, pos);
port_newdata = newdata + pos;
while (port_dlen > (int)strlen(port_str)) {
/* Find keyword, appropriate port string */
pos = search_string(port_data, port_dlen, port_str);
if (pos < 0) {
break;
}
memcpy(port_newdata, port_data, pos + 1);
port_newdata += (pos + 1);
p[0] = p[1] = 0;
sport = eport = 0;
state = 0;
for (i = pos; i < port_dlen; i++) {
switch (state) {
case 0:
if (port_data[i] == '=') {
state++;
}
break;
case 1:
if (ISDIGIT(port_data[i])) {
p[0] = p[0] * 10 + port_data[i] - '0';
} else {
if (port_data[i] == ';') {
state = 3;
}
if (port_data[i] == '-') {
state++;
}
}
break;
case 2:
if (ISDIGIT(port_data[i])) {
p[1] = p[1] * 10 + port_data[i] - '0';
} else {
state++;
}
break;
case 3:
base_port = p[0];
sport = htons(p[0]);
eport = htons(p[1]);
if (!links_created) {
links_created = 1;
/*
* Find an even numbered port
* number base that satisfies the
* contiguous number of ports we
* need
*/
null_addr.s_addr = 0;
if (0 == (salias = FindNewPortGroup(la, null_addr,
FindAliasAddress(la, pip->ip_src),
sport, 0,
RTSP_PORT_GROUP,
IPPROTO_UDP, 1))) {
#ifdef LIBALIAS_DEBUG
fprintf(stderr,
"PacketAlias/RTSP: Cannot find contiguous RTSP data ports\n");
#endif
} else {
base_alias = ntohs(salias);
for (j = 0; j < RTSP_PORT_GROUP; j++) {
/*
* Establish link
* to port found in
* RTSP packet
*/
rtsp_lnk = FindRtspOut(la, GetOriginalAddress(lnk), null_addr,
htons(base_port + j), htons(base_alias + j),
IPPROTO_UDP);
if (rtsp_lnk != NULL) {
#ifndef NO_FW_PUNCH
/*
* Punch
* hole in
* firewall
*/
PunchFWHole(rtsp_lnk);
#endif
} else {
#ifdef LIBALIAS_DEBUG
fprintf(stderr,
"PacketAlias/RTSP: Cannot allocate RTSP data ports\n");
#endif
break;
}
}
}
ealias = htons(base_alias + (RTSP_PORT_GROUP - 1));
}
if (salias && rtsp_lnk) {
pkt_updated = 1;
/* Copy into IP packet */
sprintf(stemp, "%d", ntohs(salias));
memcpy(port_newdata, stemp, strlen(stemp));
port_newdata += strlen(stemp);
if (eport != 0) {
*port_newdata = '-';
port_newdata++;
/* Copy into IP packet */
sprintf(stemp, "%d", ntohs(ealias));
memcpy(port_newdata, stemp, strlen(stemp));
port_newdata += strlen(stemp);
}
*port_newdata = ';';
port_newdata++;
}
state++;
break;
}
if (state > 3) {
break;
}
}
port_data += i;
port_dlen -= i;
}
if (!pkt_updated)
return (-1);
memcpy(port_newdata, port_data, port_dlen);
port_newdata += port_dlen;
*port_newdata = '\0';
/* Create new packet */
new_dlen = port_newdata - newdata;
memcpy(data, newdata, new_dlen);
SetAckModified(lnk);
tc = (struct tcphdr *)ip_next(pip);
delta = GetDeltaSeqOut(tc->th_seq, lnk);
AddSeq(lnk, delta + new_dlen - dlen, pip->ip_hl, pip->ip_len,
tc->th_seq, tc->th_off);
new_len = htons(hlen + new_dlen);
DifferentialChecksum(&pip->ip_sum,
&new_len,
&pip->ip_len,
1);
pip->ip_len = new_len;
tc->th_sum = 0;
#ifdef _KERNEL
tc->th_x2 = 1;
#else
tc->th_sum = TcpChecksum(pip);
#endif
return (0);
}
static void
NewFtpMessage(struct libalias *la, struct ip *pip,
struct alias_link *lnk,
int maxpacketsize,
int ftp_message_type)
{
struct alias_link *ftp_lnk;
/* Security checks. */
if (pip->ip_src.s_addr != la->true_addr.s_addr)
return;
if (la->true_port < IPPORT_RESERVED)
return;
/* Establish link to address and port found in FTP control message. */
ftp_lnk = FindUdpTcpOut(la, la->true_addr, GetDestAddress(lnk),
htons(la->true_port), 0, IPPROTO_TCP, 1);
if (ftp_lnk != NULL) {
int slen, hlen, tlen, dlen;
struct tcphdr *tc;
#ifndef NO_FW_PUNCH
/* Punch hole in firewall */
PunchFWHole(ftp_lnk);
#endif
/* Calculate data length of TCP packet */
tc = (struct tcphdr *)ip_next(pip);
hlen = (pip->ip_hl + tc->th_off) << 2;
tlen = ntohs(pip->ip_len);
dlen = tlen - hlen;
/* Create new FTP message. */
{
char stemp[MAX_MESSAGE_SIZE + 1];
char *sptr;
u_short alias_port;
u_char *ptr;
int a1, a2, a3, a4, p1, p2;
struct in_addr alias_address;
/* Decompose alias address into quad format */
alias_address = GetAliasAddress(lnk);
ptr = (u_char *) & alias_address.s_addr;
a1 = *ptr++;
a2 = *ptr++;
a3 = *ptr++;
a4 = *ptr;
alias_port = GetAliasPort(ftp_lnk);
/* Prepare new command */
switch (ftp_message_type) {
case FTP_PORT_COMMAND:
case FTP_227_REPLY:
/* Decompose alias port into pair format. */
ptr = (char *)&alias_port;
p1 = *ptr++;
p2 = *ptr;
if (ftp_message_type == FTP_PORT_COMMAND) {
/* Generate PORT command string. */
sprintf(stemp, "PORT %d,%d,%d,%d,%d,%d\r\n",
a1, a2, a3, a4, p1, p2);
} else {
/* Generate 227 reply string. */
sprintf(stemp,
"227 Entering Passive Mode (%d,%d,%d,%d,%d,%d)\r\n",
a1, a2, a3, a4, p1, p2);
}
break;
case FTP_EPRT_COMMAND:
/* Generate EPRT command string. */
sprintf(stemp, "EPRT |1|%d.%d.%d.%d|%d|\r\n",
a1, a2, a3, a4, ntohs(alias_port));
break;
case FTP_229_REPLY:
/* Generate 229 reply string. */
sprintf(stemp, "229 Entering Extended Passive Mode (|||%d|)\r\n",
ntohs(alias_port));
break;
}
/* Save string length for IP header modification */
slen = strlen(stemp);
/* Copy modified buffer into IP packet. */
sptr = (char *)pip;
sptr += hlen;
strncpy(sptr, stemp, maxpacketsize - hlen);
}
/* Save information regarding modified seq and ack numbers */
{
int delta;
SetAckModified(lnk);
tc = (struct tcphdr *)ip_next(pip);
delta = GetDeltaSeqOut(tc->th_seq, lnk);
AddSeq(lnk, delta + slen - dlen, pip->ip_hl,
pip->ip_len, tc->th_seq, tc->th_off);
}
/* Revise IP header */
{
u_short new_len;
new_len = htons(hlen + slen);
DifferentialChecksum(&pip->ip_sum,
&new_len,
&pip->ip_len,
1);
pip->ip_len = new_len;
}
/* Compute TCP checksum for revised packet */
tc->th_sum = 0;
#ifdef _KERNEL
tc->th_x2 = 1;
#else
tc->th_sum = TcpChecksum(pip);
#endif
} else {
#ifdef LIBALIAS_DEBUG
fprintf(stderr,
"PacketAlias/HandleFtpOut: Cannot allocate FTP data port\n");
#endif
}
}
static void
AliasHandleIrcOut(struct libalias *la,
struct ip *pip, /* IP packet to examine */
struct alias_link *lnk, /* Which link are we on? */
int maxsize /* Maximum size of IP packet including
* headers */
)
{
int hlen, tlen, dlen;
struct in_addr true_addr;
u_short true_port;
char *sptr;
struct tcphdr *tc;
int i; /* Iterator through the source */
/* Calculate data length of TCP packet */
tc = (struct tcphdr *)ip_next(pip);
hlen = (pip->ip_hl + tc->th_off) << 2;
tlen = ntohs(pip->ip_len);
dlen = tlen - hlen;
/*
* Return if data length is too short - assume an entire PRIVMSG in
* each packet.
*/
if (dlen < (int)sizeof(":[email protected] PRIVMSG A :aDCC 1 1a") - 1)
return;
/* Place string pointer at beginning of data */
sptr = (char *)pip;
sptr += hlen;
maxsize -= hlen; /* We're interested in maximum size of
* data, not packet */
/* Search for a CTCP command [Note 1] */
for (i = 0; i < dlen; i++) {
if (sptr[i] == '\001')
goto lFOUND_CTCP;
}
return; /* No CTCP commands in */
/* Handle CTCP commands - the buffer may have to be copied */
lFOUND_CTCP:
{
char newpacket[65536]; /* Estimate of maximum packet size
* :) */
unsigned int copyat = i; /* Same */
unsigned int iCopy = 0; /* How much data have we written to
* copy-back string? */
unsigned long org_addr; /* Original IP address */
unsigned short org_port; /* Original source port
* address */
lCTCP_START:
if (i >= dlen || iCopy >= sizeof(newpacket))
goto lPACKET_DONE;
newpacket[iCopy++] = sptr[i++]; /* Copy the CTCP start
* character */
/* Start of a CTCP */
if (i + 4 >= dlen) /* Too short for DCC */
goto lBAD_CTCP;
if (sptr[i + 0] != 'D')
goto lBAD_CTCP;
if (sptr[i + 1] != 'C')
goto lBAD_CTCP;
if (sptr[i + 2] != 'C')
goto lBAD_CTCP;
if (sptr[i + 3] != ' ')
goto lBAD_CTCP;
/* We have a DCC command - handle it! */
i += 4; /* Skip "DCC " */
if (iCopy + 4 > sizeof(newpacket))
goto lPACKET_DONE;
newpacket[iCopy++] = 'D';
newpacket[iCopy++] = 'C';
newpacket[iCopy++] = 'C';
newpacket[iCopy++] = ' ';
DBprintf(("Found DCC\n"));
/*
* Skip any extra spaces (should not occur according to
* protocol, but DCC breaks CTCP protocol anyway
*/
while (sptr[i] == ' ') {
if (++i >= dlen) {
DBprintf(("DCC packet terminated in just spaces\n"));
goto lPACKET_DONE;
}
}
DBprintf(("Transferring command...\n"));
while (sptr[i] != ' ') {
newpacket[iCopy++] = sptr[i];
if (++i >= dlen || iCopy >= sizeof(newpacket)) {
DBprintf(("DCC packet terminated during command\n"));
goto lPACKET_DONE;
}
}
/* Copy _one_ space */
if (i + 1 < dlen && iCopy < sizeof(newpacket))
newpacket[iCopy++] = sptr[i++];
DBprintf(("Done command - removing spaces\n"));
/*
* Skip any extra spaces (should not occur according to
* protocol, but DCC breaks CTCP protocol anyway
*/
while (sptr[i] == ' ') {
if (++i >= dlen) {
DBprintf(("DCC packet terminated in just spaces (post-command)\n"));
goto lPACKET_DONE;
}
}
DBprintf(("Transferring filename...\n"));
while (sptr[i] != ' ') {
newpacket[iCopy++] = sptr[i];
if (++i >= dlen || iCopy >= sizeof(newpacket)) {
DBprintf(("DCC packet terminated during filename\n"));
goto lPACKET_DONE;
}
}
/* Copy _one_ space */
if (i + 1 < dlen && iCopy < sizeof(newpacket))
newpacket[iCopy++] = sptr[i++];
DBprintf(("Done filename - removing spaces\n"));
/*
* Skip any extra spaces (should not occur according to
* protocol, but DCC breaks CTCP protocol anyway
*/
while (sptr[i] == ' ') {
if (++i >= dlen) {
DBprintf(("DCC packet terminated in just spaces (post-filename)\n"));
goto lPACKET_DONE;
}
}
DBprintf(("Fetching IP address\n"));
/* Fetch IP address */
org_addr = 0;
while (i < dlen && isdigit(sptr[i])) {
if (org_addr > ULONG_MAX / 10UL) { /* Terminate on overflow */
DBprintf(("DCC Address overflow (org_addr == 0x%08lx, next char %c\n", org_addr, sptr[i]));
goto lBAD_CTCP;
}
org_addr *= 10;
org_addr += sptr[i++] - '0';
}
DBprintf(("Skipping space\n"));
if (i + 1 >= dlen || sptr[i] != ' ') {
DBprintf(("Overflow (%d >= %d) or bad character (%02x) terminating IP address\n", i + 1, dlen, sptr[i]));
goto lBAD_CTCP;
}
/*
* Skip any extra spaces (should not occur according to
* protocol, but DCC breaks CTCP protocol anyway, so we
* might as well play it safe
*/
while (sptr[i] == ' ') {
if (++i >= dlen) {
DBprintf(("Packet failure - space overflow.\n"));
goto lPACKET_DONE;
}
}
DBprintf(("Fetching port number\n"));
/* Fetch source port */
org_port = 0;
while (i < dlen && isdigit(sptr[i])) {
if (org_port > 6554) { /* Terminate on overflow
* (65536/10 rounded up */
DBprintf(("DCC: port number overflow\n"));
goto lBAD_CTCP;
}
org_port *= 10;
org_port += sptr[i++] - '0';
}
/* Skip illegal addresses (or early termination) */
if (i >= dlen || (sptr[i] != '\001' && sptr[i] != ' ')) {
DBprintf(("Bad port termination\n"));
goto lBAD_CTCP;
}
DBprintf(("Got IP %lu and port %u\n", org_addr, (unsigned)org_port));
/* We've got the address and port - now alias it */
{
struct alias_link *dcc_lnk;
struct in_addr destaddr;
true_port = htons(org_port);
true_addr.s_addr = htonl(org_addr);
destaddr.s_addr = 0;
/* Sanity/Security checking */
if (!org_addr || !org_port ||
pip->ip_src.s_addr != true_addr.s_addr ||
org_port < IPPORT_RESERVED)
goto lBAD_CTCP;
/*
* Steal the FTP_DATA_PORT - it doesn't really
* matter, and this would probably allow it through
* at least _some_ firewalls.
*/
dcc_lnk = FindUdpTcpOut(la, true_addr, destaddr,
true_port, 0,
IPPROTO_TCP, 1);
DBprintf(("Got a DCC link\n"));
if (dcc_lnk) {
struct in_addr alias_address; /* Address from aliasing */
u_short alias_port; /* Port given by
* aliasing */
int n;
#ifndef NO_FW_PUNCH
/* Generate firewall hole as appropriate */
PunchFWHole(dcc_lnk);
#endif
alias_address = GetAliasAddress(lnk);
n = snprintf(&newpacket[iCopy],
sizeof(newpacket) - iCopy,
"%lu ", (u_long) htonl(alias_address.s_addr));
if (n < 0) {
DBprintf(("DCC packet construct failure.\n"));
goto lBAD_CTCP;
}
if ((iCopy += n) >= sizeof(newpacket)) { /* Truncated/fit exactly
* - bad news */
DBprintf(("DCC constructed packet overflow.\n"));
goto lBAD_CTCP;
}
alias_port = GetAliasPort(dcc_lnk);
n = snprintf(&newpacket[iCopy],
sizeof(newpacket) - iCopy,
"%u", htons(alias_port));
if (n < 0) {
DBprintf(("DCC packet construct failure.\n"));
goto lBAD_CTCP;
}
iCopy += n;
/*
* Done - truncated cases will be taken
* care of by lBAD_CTCP
*/
DBprintf(("Aliased IP %lu and port %u\n", alias_address.s_addr, (unsigned)alias_port));
}
}
/*
* An uninteresting CTCP - state entered right after '\001'
* has been pushed. Also used to copy the rest of a DCC,
* after IP address and port has been handled
*/
lBAD_CTCP:
for (; i < dlen && iCopy < sizeof(newpacket); i++, iCopy++) {
newpacket[iCopy] = sptr[i]; /* Copy CTCP unchanged */
if (sptr[i] == '\001') {
goto lNORMAL_TEXT;
}
}
goto lPACKET_DONE;
/* Normal text */
lNORMAL_TEXT:
for (; i < dlen && iCopy < sizeof(newpacket); i++, iCopy++) {
newpacket[iCopy] = sptr[i]; /* Copy CTCP unchanged */
if (sptr[i] == '\001') {
goto lCTCP_START;
}
}
/* Handle the end of a packet */
lPACKET_DONE:
iCopy = iCopy > maxsize - copyat ? maxsize - copyat : iCopy;
memcpy(sptr + copyat, newpacket, iCopy);
/* Save information regarding modified seq and ack numbers */
{
int delta;
SetAckModified(lnk);
delta = GetDeltaSeqOut(pip, lnk);
AddSeq(pip, lnk, delta + copyat + iCopy - dlen);
}
/* Revise IP header */
{
u_short new_len;
new_len = htons(hlen + iCopy + copyat);
DifferentialChecksum(&pip->ip_sum,
&new_len,
&pip->ip_len,
1);
pip->ip_len = new_len;
}
/* Compute TCP checksum for revised packet */
tc->th_sum = 0;
#ifdef _KERNEL
tc->th_x2 = 1;
#else
tc->th_sum = TcpChecksum(pip);
#endif
return;
}
}
