guacamole-spice-protocol/src/libguac/parser.c
2016-03-28 20:39:19 -07:00

319 lines
9.4 KiB
C

/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
#include "config.h"
#include "error.h"
#include "parser.h"
#include "socket.h"
#include "unicode.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
static void guac_parser_reset(guac_parser* parser) {
parser->opcode = NULL;
parser->argc = 0;
parser->state = GUAC_PARSE_LENGTH;
parser->__elementc = 0;
parser->__element_length = 0;
}
guac_parser* guac_parser_alloc() {
/* Allocate space for parser */
guac_parser* parser = malloc(sizeof(guac_parser));
if (parser == NULL) {
guac_error = GUAC_STATUS_NO_MEMORY;
guac_error_message = "Insufficient memory to allocate parser";
return NULL;
}
/* Init parse start/end markers */
parser->__instructionbuf_unparsed_start = parser->__instructionbuf;
parser->__instructionbuf_unparsed_end = parser->__instructionbuf;
guac_parser_reset(parser);
return parser;
}
int guac_parser_append(guac_parser* parser, void* buffer, int length) {
char* char_buffer = (char*) buffer;
int bytes_parsed = 0;
/* Do not exceed maximum number of elements */
if (parser->__elementc == GUAC_INSTRUCTION_MAX_ELEMENTS
&& parser->state != GUAC_PARSE_COMPLETE) {
parser->state = GUAC_PARSE_ERROR;
return 0;
}
/* Parse element length */
if (parser->state == GUAC_PARSE_LENGTH) {
int parsed_length = parser->__element_length;
while (bytes_parsed < length) {
/* Pull next character */
char c = *(char_buffer++);
bytes_parsed++;
/* If digit, add to length */
if (c >= '0' && c <= '9')
parsed_length = parsed_length*10 + c - '0';
/* If period, switch to parsing content */
else if (c == '.') {
parser->__elementv[parser->__elementc++] = char_buffer;
parser->state = GUAC_PARSE_CONTENT;
break;
}
/* If not digit, parse error */
else {
parser->state = GUAC_PARSE_ERROR;
return 0;
}
}
/* If too long, parse error */
if (parsed_length > GUAC_INSTRUCTION_MAX_LENGTH) {
parser->state = GUAC_PARSE_ERROR;
return 0;
}
/* Save length */
parser->__element_length = parsed_length;
} /* end parse length */
/* Parse element content */
if (parser->state == GUAC_PARSE_CONTENT) {
while (bytes_parsed < length && parser->__element_length >= 0) {
/* Get length of current character */
char c = *char_buffer;
int char_length = guac_utf8_charsize((unsigned char) c);
/* If full character not present in buffer, stop now */
if (char_length + bytes_parsed > length)
break;
/* Record character as parsed */
bytes_parsed += char_length;
/* If end of element, handle terminator */
if (parser->__element_length == 0) {
*char_buffer = '\0';
/* If semicolon, store end-of-instruction */
if (c == ';') {
parser->state = GUAC_PARSE_COMPLETE;
parser->opcode = parser->__elementv[0];
parser->argv = &(parser->__elementv[1]);
parser->argc = parser->__elementc - 1;
break;
}
/* If comma, move on to next element */
else if (c == ',') {
parser->state = GUAC_PARSE_LENGTH;
break;
}
/* Otherwise, parse error */
else {
parser->state = GUAC_PARSE_ERROR;
return 0;
}
} /* end if end of element */
/* Advance to next character */
parser->__element_length--;
char_buffer += char_length;
}
} /* end parse content */
return bytes_parsed;
}
int guac_parser_read(guac_parser* parser, guac_socket* socket, int usec_timeout) {
char* unparsed_end = parser->__instructionbuf_unparsed_end;
char* unparsed_start = parser->__instructionbuf_unparsed_start;
char* instr_start = parser->__instructionbuf_unparsed_start;
char* buffer_end = parser->__instructionbuf + sizeof(parser->__instructionbuf);
/* Begin next instruction if previous was ended */
if (parser->state == GUAC_PARSE_COMPLETE)
guac_parser_reset(parser);
while (parser->state != GUAC_PARSE_COMPLETE
&& parser->state != GUAC_PARSE_ERROR) {
/* Add any available data to buffer */
int parsed = guac_parser_append(parser, unparsed_start, unparsed_end - unparsed_start);
/* Read more data if not enough data to parse */
if (parsed == 0 && parser->state != GUAC_PARSE_ERROR) {
int retval;
/* If no space left to read, fail */
if (unparsed_end == buffer_end) {
/* Shift backward if possible */
if (instr_start != parser->__instructionbuf) {
int i;
/* Shift buffer */
int offset = instr_start - parser->__instructionbuf;
memmove(parser->__instructionbuf, instr_start,
unparsed_end - instr_start);
/* Update tracking pointers */
unparsed_end -= offset;
unparsed_start -= offset;
instr_start = parser->__instructionbuf;
/* Update parsed elements, if any */
for (i=0; i < parser->__elementc; i++)
parser->__elementv[i] -= offset;
}
/* Otherwise, no memory to read */
else {
guac_error = GUAC_STATUS_NO_MEMORY;
guac_error_message = "Instruction too long";
return -1;
}
}
/* No instruction yet? Get more data ... */
retval = guac_socket_select(socket, usec_timeout);
if (retval <= 0)
return -1;
/* Attempt to fill buffer */
retval = guac_socket_read(socket, unparsed_end,
buffer_end - unparsed_end);
/* Set guac_error if read unsuccessful */
if (retval < 0) {
guac_error = GUAC_STATUS_SEE_ERRNO;
guac_error_message = "Error filling instruction buffer";
return -1;
}
/* EOF */
if (retval == 0) {
guac_error = GUAC_STATUS_CLOSED;
guac_error_message = "End of stream reached while "
"reading instruction";
return -1;
}
/* Update internal buffer */
unparsed_end += retval;
}
/* If data was parsed, advance buffer */
else
unparsed_start += parsed;
} /* end while parsing data */
/* Fail on error */
if (parser->state == GUAC_PARSE_ERROR) {
guac_error = GUAC_STATUS_PROTOCOL_ERROR;
guac_error_message = "Instruction parse error";
return -1;
}
parser->__instructionbuf_unparsed_start = unparsed_start;
parser->__instructionbuf_unparsed_end = unparsed_end;
return 0;
}
int guac_parser_expect(guac_parser* parser, guac_socket* socket, int usec_timeout, const char* opcode) {
/* Read next instruction */
if (guac_parser_read(parser, socket, usec_timeout) != 0)
return -1;
/* Validate instruction */
if (strcmp(parser->opcode, opcode) != 0) {
guac_error = GUAC_STATUS_PROTOCOL_ERROR;
guac_error_message = "Instruction read did not have expected opcode";
return -1;
}
/* Return non-zero only if valid instruction read */
return parser->state != GUAC_PARSE_COMPLETE;
}
int guac_parser_length(guac_parser* parser) {
char* unparsed_end = parser->__instructionbuf_unparsed_end;
char* unparsed_start = parser->__instructionbuf_unparsed_start;
return unparsed_end - unparsed_start;
}
int guac_parser_shift(guac_parser* parser, void* buffer, int length) {
char* copy_end = parser->__instructionbuf_unparsed_end;
char* copy_start = parser->__instructionbuf_unparsed_start;
/* Contain copy region within length */
if (copy_end - copy_start > length)
copy_end = copy_start + length;
/* Copy buffer */
length = copy_end - copy_start;
memcpy(buffer, copy_start, length);
parser->__instructionbuf_unparsed_start = copy_end;
return length;
}
void guac_parser_free(guac_parser* parser) {
free(parser);
}