diff options
Diffstat (limited to 'plugins/telnet/telnet_proto.c')
| -rw-r--r-- | plugins/telnet/telnet_proto.c | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/plugins/telnet/telnet_proto.c b/plugins/telnet/telnet_proto.c new file mode 100644 index 0000000..523c68c --- /dev/null +++ b/plugins/telnet/telnet_proto.c @@ -0,0 +1,213 @@ +#include "telnet_proto.h" + +#include "hybbx/socket.h" + +#include <errno.h> +#include <string.h> +#include <unistd.h> + +#define TELNET_IAC 255 +#define TELNET_DONT 254 +#define TELNET_DO 253 +#define TELNET_WONT 252 +#define TELNET_WILL 251 +#define TELNET_SB 250 +#define TELNET_GA 249 +#define TELNET_EL 248 +#define TELNET_EC 247 +#define TELNET_AYT 246 +#define TELNET_AO 245 +#define TELNET_IP 244 +#define TELNET_BRK 243 +#define TELNET_DM 242 +#define TELNET_NOP 241 +#define TELNET_SE 240 + +#define TELNET_OPT_ECHO 1 +#define TELNET_OPT_SGA 3 +#define TELNET_OPT_TTYPE 24 +#define TELNET_OPT_NAWS 31 +#define TELNET_OPT_LINEMODE 34 +#define TELNET_OPT_CHARSET 42 + +enum telnet_parse_state { + TS_DATA = 0, + TS_IAC, + TS_CMD, + TS_SUBNEG, + TS_SUBNEG_IAC +}; + +static hybbx_result_t telnet_send_raw(int fd, const uint8_t *data, size_t len) +{ + size_t sent_total = 0; + + while (sent_total < len) { + ssize_t sent; + + sent = send(fd, data + sent_total, len - sent_total, MSG_NOSIGNAL); + if (sent < 0) { + if (errno == EINTR) { + continue; + } + return HYBBX_ERR_IO; + } + if (sent == 0) { + return HYBBX_ERR_IO; + } + + sent_total += (size_t)sent; + } + + return HYBBX_OK; +} + +static hybbx_result_t telnet_send_option(int fd, uint8_t cmd, uint8_t option) +{ + uint8_t buf[3]; + + buf[0] = TELNET_IAC; + buf[1] = cmd; + buf[2] = option; + return telnet_send_raw(fd, buf, sizeof(buf)); +} + +static hybbx_result_t telnet_reply_do(int fd, uint8_t option) +{ + switch (option) { + case TELNET_OPT_ECHO: + return telnet_send_option(fd, TELNET_WONT, option); + case TELNET_OPT_SGA: + return telnet_send_option(fd, TELNET_WILL, option); + case TELNET_OPT_TTYPE: + case TELNET_OPT_NAWS: + case TELNET_OPT_LINEMODE: + case TELNET_OPT_CHARSET: + return telnet_send_option(fd, TELNET_WONT, option); + default: + return telnet_send_option(fd, TELNET_WONT, option); + } +} + +static hybbx_result_t telnet_reply_will(int fd, uint8_t option) +{ + switch (option) { + case TELNET_OPT_SGA: + return telnet_send_option(fd, TELNET_DO, option); + case TELNET_OPT_ECHO: + return telnet_send_option(fd, TELNET_DONT, option); + default: + return telnet_send_option(fd, TELNET_DONT, option); + } +} + +static void emit_byte(hybbx_telnet_data_cb on_data, void *ctx, uint8_t byte) +{ + if (on_data != NULL) { + on_data(ctx, &byte, 1); + } +} + +void hybbx_telnet_parser_init(hybbx_telnet_parser_t *parser) +{ + if (parser == NULL) { + return; + } + + parser->state = TS_DATA; + parser->command = 0; +} + +hybbx_result_t hybbx_telnet_send_greeting(int fd) +{ + static const uint8_t greeting[] = { + TELNET_IAC, TELNET_WONT, TELNET_OPT_ECHO, + TELNET_IAC, TELNET_WILL, TELNET_OPT_SGA, + TELNET_IAC, TELNET_DONT, TELNET_OPT_LINEMODE, + }; + + if (fd < 0) { + return HYBBX_ERR_INVALID; + } + + return telnet_send_raw(fd, greeting, sizeof(greeting)); +} + +hybbx_result_t hybbx_telnet_parser_feed(hybbx_telnet_parser_t *parser, int fd, + const uint8_t *data, size_t len, + hybbx_telnet_data_cb on_data, + void *ctx) +{ + size_t i; + hybbx_result_t rc; + + if (parser == NULL || data == NULL) { + return HYBBX_ERR_INVALID; + } + + for (i = 0; i < len; i++) { + uint8_t byte = data[i]; + + switch (parser->state) { + case TS_DATA: + if (byte == TELNET_IAC) { + parser->state = TS_IAC; + } else { + emit_byte(on_data, ctx, byte); + } + break; + + case TS_IAC: + if (byte == TELNET_IAC) { + emit_byte(on_data, ctx, TELNET_IAC); + parser->state = TS_DATA; + } else if (byte == TELNET_WILL || byte == TELNET_WONT || + byte == TELNET_DO || byte == TELNET_DONT) { + parser->command = (int)byte; + parser->state = TS_CMD; + } else if (byte == TELNET_SB) { + parser->state = TS_SUBNEG; + } else { + parser->state = TS_DATA; + } + break; + + case TS_CMD: + if (fd >= 0) { + if (parser->command == TELNET_DO) { + rc = telnet_reply_do(fd, byte); + if (rc != HYBBX_OK) { + return rc; + } + } else if (parser->command == TELNET_WILL) { + rc = telnet_reply_will(fd, byte); + if (rc != HYBBX_OK) { + return rc; + } + } + } + parser->state = TS_DATA; + break; + + case TS_SUBNEG: + if (byte == TELNET_IAC) { + parser->state = TS_SUBNEG_IAC; + } + break; + + case TS_SUBNEG_IAC: + if (byte == TELNET_SE) { + parser->state = TS_DATA; + } else { + parser->state = TS_SUBNEG; + } + break; + + default: + parser->state = TS_DATA; + break; + } + } + + return HYBBX_OK; +} |