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Commit 4fd92c4e authored by Rob Swindell's avatar Rob Swindell :speech_balloon:
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telnet_gateway() is now, by default, a telnet proxy 

Meaning, it'll negotiate all Telnet options with the remote server (assuming
not an RLogin server), so long as the TG_PASSTHRU option is *not* set.

This allows more Telnet servers to work as expected, especially when the
client (BBS user) is not using a Telnet client!

Fix issue #432
parent f1bac4e4
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with 204 additions and 25 deletions
src/sbbs3/telgate.cpp
+ 204
− 25
View file @ 4fd92c4e
......@@ -20,14 +20,207 @@
****************************************************************************/
#include "sbbs.h"
#include "telnet.h"
#include "telnet.h"
struct TelnetProxy
{
SOCKET sock;
uint8_t local_option[0x100]{};
uint8_t remote_option[0x100]{};
sbbs_t* sbbs;
int cmdlen = 0;
uint8_t cmd[64];
uint8_t outbuf[1024];
TelnetProxy(SOCKET sock_, sbbs_t* sbbs_)
: sock{sock_}, sbbs{sbbs_} {}
void send(uint8_t cmd, uint8_t opt)
{
char buf[16];
if (cmd < TELNET_WILL) {
if(sbbs->startup->options&BBS_OPT_DEBUG_TELNET)
sbbs->lprintf(LOG_DEBUG, __FUNCTION__ ": %s", telnet_cmd_desc(cmd));
sprintf(buf, "%c%c", TELNET_IAC, cmd);
if (::sendsocket(sock, buf, 2) != 2)
lprintf(LOG_WARNING, "Failed to send Telnet command: %s", telnet_cmd_desc(cmd));
}
else {
if(sbbs->startup->options&BBS_OPT_DEBUG_TELNET)
sbbs->lprintf(LOG_DEBUG, __FUNCTION__ ": %s %s", telnet_cmd_desc(cmd), telnet_opt_desc(opt));
sprintf(buf, "%c%c%c", TELNET_IAC, cmd, opt);
if (::sendsocket(sock, buf, 3) != 3)
sbbs->lprintf(LOG_WARNING, "Failed to send Telnet command: %s %s", telnet_cmd_desc(cmd), telnet_opt_desc(opt));
}
}
void request_opt(uint8_t cmd, uint8_t opt)
{
if ((cmd == TELNET_DO) || (cmd == TELNET_DONT)) { /* remote option */
if (remote_option[opt] == telnet_opt_ack(cmd))
return; /* already set in this mode, do nothing */
remote_option[opt] = telnet_opt_ack(cmd);
}
else { /* local option */
if (local_option[opt] == telnet_opt_ack(cmd))
return; /* already set in this mode, do nothing */
local_option[opt] = telnet_opt_ack(cmd);
}
send(cmd, opt);
}
uint8_t* recv(uint8_t *inbuf, size_t inlen, ssize_t& outlen)
{
uint8_t command;
uint8_t option;
uint8_t *first_int = NULL;
if (inlen < 1) {
outlen = 0;
return inbuf; /* no length? No interpretation */
}
first_int = (uint8_t *)memchr(inbuf, TELNET_IAC, inlen);
if ((cmdlen == 0) && (first_int == NULL)) {
outlen = inlen;
return inbuf; /* no interpretation needed */
}
if (cmdlen == 0 /* If we haven't returned and cmdlen==0 then first_int is not NULL */) {
outlen = first_int - inbuf;
memcpy(outbuf, inbuf, outlen);
}
else {
outlen = 0;
}
for (size_t i = outlen; i < inlen; i++) {
if (remote_option[TELNET_BINARY_TX] != TELNET_WILL) {
if ((cmdlen == 1) && (cmd[0] == '\r')) {
outbuf[outlen++] = '\r';
if ((inbuf[i] != 0) && (inbuf[i] != TELNET_IAC))
outbuf[outlen++] = inbuf[i];
cmdlen = 0;
if (inbuf[i] != TELNET_IAC)
continue;
}
if ((inbuf[i] == '\r') && (cmdlen == 0)) {
cmd[cmdlen++] = '\r';
continue;
}
}
if ((inbuf[i] == TELNET_IAC) && (cmdlen == 1)) { /* escaped 255 */
cmdlen = 0;
outbuf[outlen++] = TELNET_IAC;
continue;
}
if ((inbuf[i] == TELNET_IAC) || cmdlen) {
if (cmdlen < sizeof(cmd))
cmd[cmdlen++] = inbuf[i];
command = cmd[1];
option = cmd[2];
if ((cmdlen >= 2) && (command == TELNET_SB)) {
if ((inbuf[i] == TELNET_SE)
&& (cmd[cmdlen - 2] == TELNET_IAC)) {
/* sub-option terminated */
if ((option == TELNET_TERM_TYPE) && (cmd[3] == TELNET_TERM_SEND)) {
char buf[32];
int len = snprintf(buf, sizeof buf, "%c%c%c%c%s%c%c",
TELNET_IAC, TELNET_SB,
TELNET_TERM_TYPE, TELNET_TERM_IS,
sbbs->term_type(),
TELNET_IAC, TELNET_SE);
::sendsocket(sock, buf, len);
request_opt(TELNET_WILL, TELNET_NEGOTIATE_WINDOW_SIZE);
}
cmdlen = 0;
}
}
else if ((cmdlen == 2) && (inbuf[i] < TELNET_WILL)) {
cmdlen = 0;
}
else if (cmdlen >= 3) { /* telnet option negotiation */
if(sbbs->startup->options&BBS_OPT_DEBUG_TELNET)
sbbs->lprintf(LOG_DEBUG, __FUNCTION__ ": %s %s",
telnet_cmd_desc(command), telnet_opt_desc(option));
if ((command == TELNET_DO) || (command == TELNET_DONT)) { /* local options */
if (local_option[option] != command) {
switch (option) {
case TELNET_BINARY_TX:
case TELNET_TERM_TYPE:
case TELNET_SUP_GA:
case TELNET_NEGOTIATE_WINDOW_SIZE:
local_option[option] = command;
send(telnet_opt_ack(command), option);
break;
default: // unsupported local options
if (command == TELNET_DO) /* NAK */
send(telnet_opt_nak(command),
option);
break;
}
}
if ((command == TELNET_DO) && (option == TELNET_NEGOTIATE_WINDOW_SIZE)) {
uint8_t buf[32];
buf[0] = TELNET_IAC;
buf[1] = TELNET_SB;
buf[2] = TELNET_NEGOTIATE_WINDOW_SIZE;
buf[3] = (sbbs->cols >> 8) & 0xff;
buf[4] = sbbs->cols & 0xff;
buf[5] = (sbbs->rows >> 8) & 0xff;
buf[6] = sbbs->rows & 0xff;
buf[7] = TELNET_IAC;
buf[8] = TELNET_SE;
if(sbbs->startup->options&BBS_OPT_DEBUG_TELNET)
sbbs->lprintf(LOG_DEBUG, __FUNCTION__ ": Window Size is %u x %u", sbbs->cols, sbbs->rows);
::sendsocket(sock, (char *)buf, 9);
}
}
else { /* WILL/WONT (remote options) */
if (remote_option[option] != command) {
switch (option) {
case TELNET_BINARY_TX:
case TELNET_ECHO:
case TELNET_TERM_TYPE:
case TELNET_SUP_GA:
case TELNET_NEGOTIATE_WINDOW_SIZE:
remote_option[option] = command;
send(telnet_opt_ack(command), option);
break;
default: // unsupported remote options
if (command == TELNET_WILL) /* NAK */
send(telnet_opt_nak(command), option);
break;
}
}
}
cmdlen = 0;
}
}
else {
outbuf[outlen++] = inbuf[i];
}
}
return outbuf;
}
}; // struct TelnetProxy
bool sbbs_t::telnet_gate(char* destaddr, uint mode, unsigned timeout, char* client_user_name, char* server_user_name, char* term_type)
{
char* p;
uchar buf[512];
int i;
int rd;
ssize_t rd;
uint attempts;
u_long l;
bool gotline;
......@@ -36,6 +229,7 @@ bool sbbs_t::telnet_gate(char* destaddr, uint mode, unsigned timeout, char* clie
uint save_console;
SOCKET remote_socket;
SOCKADDR_IN addr;
TelnetProxy* proxy = nullptr;
if(mode&TG_RLOGIN)
port=513;
......@@ -77,7 +271,6 @@ bool sbbs_t::telnet_gate(char* destaddr, uint mode, unsigned timeout, char* clie
addr.sin_port = htons(port);
l=1;
if((i = ioctlsocket(remote_socket, FIONBIO, &l))!=0) {
lprintf(LOG_NOTICE,"!TELGATE ERROR %d (%d) disabling socket blocking"
,i, ERROR_VALUE);
......@@ -122,6 +315,10 @@ bool sbbs_t::telnet_gate(char* destaddr, uint mode, unsigned timeout, char* clie
if(sendsocket(remote_socket,(char*)buf,l) != (ssize_t)l)
lprintf(LOG_WARNING, "Error %d sending %lu bytes to server: %s", ERROR_VALUE, l, destaddr);
mode|=TG_NOLF; /* Send LF (to remote host) when Telnet client sends CRLF (when not in binary mode) */
} else {
proxy = new TelnetProxy(remote_socket, this);
if(!(mode & TG_ECHO))
proxy->request_opt(TELNET_DO, TELNET_ECHO);
}
/* This is required for gating to Unix telnetd */
......@@ -130,7 +327,6 @@ bool sbbs_t::telnet_gate(char* destaddr, uint mode, unsigned timeout, char* clie
/* Text/NVT mode by default */
request_telnet_opt(TELNET_DONT,TELNET_BINARY_TX, 3000);
if(!(telnet_mode&TELNET_MODE_OFF) && (mode&TG_PASSTHRU))
telnet_mode|=TELNET_MODE_GATE; // Pass-through telnet commands
......@@ -139,16 +335,6 @@ bool sbbs_t::telnet_gate(char* destaddr, uint mode, unsigned timeout, char* clie
gettimeleft();
rd=RingBufRead(&inbuf,buf,sizeof(buf)-1);
if(rd) {
#if 0
if(memchr(buf,TELNET_IAC,rd)) {
char dump[2048];
dump[0];
p=dump;
for(int i=0;i<rd;i++)
p+=sprintf(p,"%u ",buf[i]);
lprintf(LOG_DEBUG,"Node %d Telnet cmd from client: %s", cfg.node_num, dump);
}
#endif
if(telnet_remote_option[TELNET_BINARY_TX]!=TELNET_WILL) {
if(*buf==CTRL_CLOSE_BRACKET) {
save_console=console;
......@@ -240,17 +426,10 @@ bool sbbs_t::telnet_gate(char* destaddr, uint mode, unsigned timeout, char* clie
lprintf(LOG_INFO,"Node %d Telnet gate disconnected",cfg.node_num);
break;
}
#if 0
if(memchr(buf,TELNET_IAC,rd)) {
char dump[2048];
dump[0];
p=dump;
for(int i=0;i<rd;i++)
p+=sprintf(p,"%u ",buf[i]);
lprintf(LOG_DEBUG,"Node %d Telnet cmd from server: %s", cfg.node_num, dump);
}
#endif
RingBufWrite(&outbuf,buf,rd);
uint8_t* p = buf;
if(!(mode & (TG_RLOGIN | TG_PASSTHRU)))
p = proxy->recv(buf, rd, rd);
RingBufWrite(&outbuf,p,rd);
}
console&=~CON_RAW_IN;
telnet_mode&=~TELNET_MODE_GATE;
......
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