GUACAMOLE-662: Merge correct behavior of nested socket.
This commit is contained in:
Nick Couchman
commit
bb9560716d
@ -25,80 +25,237 @@
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#include <stddef.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#define GUAC_SOCKET_NEST_BUFFER_SIZE 8192
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/**
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* The maximum number of bytes to buffer before sending a "nest" instruction.
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* As some of the 8 KB space available for each instruction will be taken up by
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* the "nest" opcode and other parameters, and 1 KB will be more than enough
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* space for that extra data, this space is reduced to an even 7 KB.
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*/
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#define GUAC_SOCKET_NEST_BUFFER_SIZE 7168
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typedef struct __guac_socket_nest_data {
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/**
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* Internal data associated with an open socket which writes via a series of
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* "nest" instructions to some underlying, parent socket.
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*/
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typedef struct guac_socket_nest_data {
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/**
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* The underlying socket which should be used to write "nest" instructions.
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*/
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guac_socket* parent;
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char buffer[GUAC_SOCKET_NEST_BUFFER_SIZE];
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/**
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* The arbitrary index of the nested socket, assigned at time of
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* allocation.
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*/
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int index;
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} __guac_socket_nest_data;
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/**
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* The number of bytes currently in the main write buffer.
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*/
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int written;
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ssize_t __guac_socket_nest_write_handler(guac_socket* socket,
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/**
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* The main write buffer. Bytes written go here before being flushed
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* as nest instructions. Space is included for the null terminator
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* required by guac_protocol_send_nest().
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*/
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char buffer[GUAC_SOCKET_NEST_BUFFER_SIZE];
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/**
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* Lock which is acquired when an instruction is being written, and
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* released when the instruction is finished being written.
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*/
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pthread_mutex_t socket_lock;
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/**
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* Lock which protects access to the internal buffer of this socket,
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* guaranteeing atomicity of writes and flushes.
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*/
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pthread_mutex_t buffer_lock;
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} guac_socket_nest_data;
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/**
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* Flushes the contents of the output buffer of the given socket immediately,
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* without first locking access to the output buffer. This function must ONLY
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* be called if the buffer lock has already been acquired.
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*
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* @param socket
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* The guac_socket to flush.
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*
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* @return
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* Zero if the flush operation was successful, non-zero otherwise.
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*/
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static ssize_t guac_socket_nest_flush(guac_socket* socket) {
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guac_socket_nest_data* data = (guac_socket_nest_data*) socket->data;
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/* Flush remaining bytes in buffer */
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if (data->written > 0) {
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/* Determine length of buffer containing complete UTF-8 characters
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* (buffer may end with a partial, multi-byte character) */
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int length = 0;
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while (length < data->written)
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length += guac_utf8_charsize(*(data->buffer + length));
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/* Add null terminator, preserving overwritten character for later
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* restoration (guac_protocol_send_nest() requires null-terminated
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* strings) */
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char overwritten = data->buffer[length];
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data->buffer[length] = '\0';
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/* Write ALL bytes in buffer as nest instruction */
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int retval = guac_protocol_send_nest(data->parent, data->index, data->buffer);
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/* Restore original value overwritten by null terminator */
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data->buffer[length] = overwritten;
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if (retval)
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return 1;
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/* Shift any remaining data to beginning of buffer */
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memcpy(data->buffer, data->buffer + length, data->written - length);
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data->written -= length;
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}
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return 0;
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}
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/**
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* Flushes the internal buffer of the given guac_socket, writing all data
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* to the underlying socket using "nest" instructions.
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*
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* @param socket
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* The guac_socket to flush.
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*
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* @return
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* Zero if the flush operation was successful, non-zero otherwise.
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*/
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static ssize_t guac_socket_nest_flush_handler(guac_socket* socket) {
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int retval;
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guac_socket_nest_data* data = (guac_socket_nest_data*) socket->data;
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/* Acquire exclusive access to buffer */
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pthread_mutex_lock(&(data->buffer_lock));
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/* Flush contents of buffer */
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retval = guac_socket_nest_flush(socket);
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/* Relinquish exclusive access to buffer */
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pthread_mutex_unlock(&(data->buffer_lock));
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return retval;
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}
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/**
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* Writes the contents of the buffer to the output buffer of the given socket,
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* flushing the output buffer as necessary, without first locking access to the
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* output buffer. This function must ONLY be called if the buffer lock has
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* already been acquired.
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*
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* @param socket
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* The guac_socket to write the given buffer to.
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*
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* @param buf
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* The buffer to write to the given socket.
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*
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* @param count
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* The number of bytes in the given buffer.
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*
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* @return
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* The number of bytes written, or a negative value if an error occurs
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* during write.
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*/
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static ssize_t guac_socket_nest_write_buffered(guac_socket* socket,
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const void* buf, size_t count) {
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__guac_socket_nest_data* data = (__guac_socket_nest_data*) socket->data;
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unsigned char* source = (unsigned char*) buf;
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size_t original_count = count;
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const char* current = buf;
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guac_socket_nest_data* data = (guac_socket_nest_data*) socket->data;
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/* Current location in destination buffer during copy */
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char* current = data->buffer;
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/* Append to buffer, flush if necessary */
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while (count > 0) {
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/* Number of bytes remaining in source buffer */
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int remaining = count;
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int chunk_size;
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/* If we can't actually store that many bytes, reduce number of bytes
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* expected to be written */
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if (remaining > GUAC_SOCKET_NEST_BUFFER_SIZE)
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remaining = GUAC_SOCKET_NEST_BUFFER_SIZE;
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/* Calculate space remaining, including one extra byte for the null
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* terminator added upon flush */
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int remaining = sizeof(data->buffer) - data->written - 1;
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/* Current offset within destination buffer */
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int offset;
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/* If no space left in buffer, flush and retry */
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if (remaining == 0) {
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/* Number of characters before start of next character */
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int skip = 0;
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/* Abort if error occurs during flush */
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if (guac_socket_nest_flush(socket))
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return -1;
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/* Copy UTF-8 characters into buffer */
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for (offset = 0; offset < GUAC_SOCKET_NEST_BUFFER_SIZE; offset++) {
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/* Get next byte */
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unsigned char c = *source;
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remaining--;
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/* If skipping, then skip */
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if (skip > 0) skip--;
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/* Otherwise, determine next skip value, and increment length */
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else {
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/* Determine skip value (size in bytes of rest of character) */
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skip = guac_utf8_charsize(c) - 1;
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/* If not enough bytes to complete character, break */
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if (skip > remaining)
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break;
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/* Retry buffer append */
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continue;
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}
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/* Store byte */
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*current = c;
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/* Calculate size of chunk to be written to buffer */
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chunk_size = count;
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if (chunk_size > remaining)
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chunk_size = remaining;
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/* Advance to next character */
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source++;
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current++;
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/* Update output buffer */
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memcpy(data->buffer + data->written, current, chunk_size);
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data->written += chunk_size;
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/* Update provided buffer */
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current += chunk_size;
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count -= chunk_size;
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}
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/* Append null-terminator */
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*current = 0;
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/* All bytes have been written, possibly some to the internal buffer */
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return original_count;
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/* Send nest instruction containing read UTF-8 segment */
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guac_protocol_send_nest(data->parent, data->index, data->buffer);
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}
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/* Return number of bytes actually written */
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return offset;
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/**
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* Appends the provided data to the internal buffer for future writing. The
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* actual write attempt will occur only upon flush, or when the internal buffer
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* is full.
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*
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* @param socket
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* The guac_socket being write to.
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*
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* @param buf
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* The arbitrary buffer containing the data to be written.
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*
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* @param count
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* The number of bytes contained within the buffer.
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*
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* @return
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* The number of bytes written, or -1 if an error occurs.
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*/
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static ssize_t guac_socket_nest_write_handler(guac_socket* socket,
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const void* buf, size_t count) {
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int retval;
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guac_socket_nest_data* data = (guac_socket_nest_data*) socket->data;
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/* Acquire exclusive access to buffer */
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pthread_mutex_lock(&(data->buffer_lock));
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/* Write provided data to buffer */
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retval = guac_socket_nest_write_buffered(socket, buf, count);
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/* Relinquish exclusive access to buffer */
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pthread_mutex_unlock(&(data->buffer_lock));
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return retval;
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}
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@ -113,29 +270,63 @@ ssize_t __guac_socket_nest_write_handler(guac_socket* socket,
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* Zero if the data was successfully freed, non-zero otherwise. This
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* implementation always succeeds, and will always return zero.
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*/
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static int __guac_socket_nest_free_handler(guac_socket* socket) {
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static int guac_socket_nest_free_handler(guac_socket* socket) {
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/* Free associated data */
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__guac_socket_nest_data* data = (__guac_socket_nest_data*) socket->data;
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guac_socket_nest_data* data = (guac_socket_nest_data*) socket->data;
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free(data);
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return 0;
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}
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/**
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* Acquires exclusive access to the given socket.
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*
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* @param socket
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* The guac_socket to which exclusive access is required.
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*/
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static void guac_socket_nest_lock_handler(guac_socket* socket) {
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guac_socket_nest_data* data = (guac_socket_nest_data*) socket->data;
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/* Acquire exclusive access to socket */
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pthread_mutex_lock(&(data->socket_lock));
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}
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/**
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* Relinquishes exclusive access to the given socket.
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*
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* @param socket
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* The guac_socket to which exclusive access is no longer required.
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*/
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static void guac_socket_nest_unlock_handler(guac_socket* socket) {
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guac_socket_nest_data* data = (guac_socket_nest_data*) socket->data;
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/* Relinquish exclusive access to socket */
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pthread_mutex_unlock(&(data->socket_lock));
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}
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guac_socket* guac_socket_nest(guac_socket* parent, int index) {
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/* Allocate socket and associated data */
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guac_socket* socket = guac_socket_alloc();
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__guac_socket_nest_data* data = malloc(sizeof(__guac_socket_nest_data));
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guac_socket_nest_data* data = malloc(sizeof(guac_socket_nest_data));
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/* Store file descriptor as socket data */
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/* Store nested socket details as socket data */
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data->parent = parent;
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data->index = index;
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socket->data = data;
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/* Set write and free handlers */
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socket->write_handler = __guac_socket_nest_write_handler;
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socket->free_handler = __guac_socket_nest_free_handler;
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/* Set relevant handlers */
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socket->write_handler = guac_socket_nest_write_handler;
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socket->lock_handler = guac_socket_nest_lock_handler;
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socket->unlock_handler = guac_socket_nest_unlock_handler;
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socket->flush_handler = guac_socket_nest_flush_handler;
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socket->free_handler = guac_socket_nest_free_handler;
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return socket;
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