GUACAMOLE-325: Add Winsock-specific guac_socket implementation.

src/libguac/Makefile.am

@@ -108,6 +108,12 @@ libguac_la_SOURCES += socket-ssl.c
 libguacinc_HEADERS += guacamole/socket-ssl.h
 endif
 
+# Winsock support
+if ENABLE_WINSOCK
+libguac_la_SOURCES += socket-wsa.c
+libguacinc_HEADERS += guacamole/socket-wsa.h
+endif
+
 libguac_la_CFLAGS = \
     -Werror -Wall -pedantic -Iguacamole
 

src/libguac/guacamole/socket-wsa.h

@@ -0,0 +1,51 @@
+/*
+ * 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.
+ */
+
+#ifndef GUAC_SOCKET_WSA_H
+#define GUAC_SOCKET_WSA_H
+
+/**
+ * Provides an implementation of guac_socket specific to the Windows Socket API
+ * (aka WSA or "winsock"). This header will only be available if libguac was
+ * built with WSA support.
+ *
+ * @file socket-wsa.h
+ */
+
+#include "socket-types.h"
+
+#include <winsock2.h>
+
+/**
+ * Creates a new guac_socket which will use the Windows Socket API (aka WSA or
+ * "winsock") for all communication. Freeing this guac_socket will
+ * automatically close the associated SOCKET handle.
+ *
+ * @param sock
+ *     The WSA SOCKET handle to use for the connection underlying the created
+ *     guac_socket.
+ *
+ * @return
+ *     A newly-allocated guac_socket which will transparently use the Windows
+ *     Socket API for all communication.
+ */
+guac_socket* guac_socket_open_wsa(SOCKET sock);
+
+#endif
+

src/libguac/socket-wsa.c

@@ -0,0 +1,448 @@
+/*
+ * 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 "error.h"
+#include "socket.h"
+
+#include <pthread.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <winsock2.h>
+
+/**
+ * Data associated with an open socket which uses the Windows Socket API.
+ */
+typedef struct guac_socket_wsa_data {
+
+    /**
+     * The associated Windows socket handle.
+     */
+    SOCKET sock;
+
+    /**
+     * The number of bytes currently in the main write buffer.
+     */
+    int written;
+
+    /**
+     * The main write buffer. Bytes written go here before being flushed
+     * to the open socket.
+     */
+    char out_buf[GUAC_SOCKET_OUTPUT_BUFFER_SIZE];
+
+    /**
+     * Lock which is acquired when an instruction is being written, and
+     * released when the instruction is finished being written.
+     */
+    pthread_mutex_t socket_lock;
+
+    /**
+     * Lock which protects access to the internal buffer of this socket,
+     * guaranteeing atomicity of writes and flushes.
+     */
+    pthread_mutex_t buffer_lock;
+
+} guac_socket_wsa_data;
+
+/**
+ * Writes the entire contents of the given buffer to the SOCKET handle
+ * associated with the given socket, retrying as necessary until the whole
+ * buffer is written, and aborting if an error occurs.
+ *
+ * @param socket
+ *     The guac_socket associated with the SOCKET handle to which the given
+ *     buffer should be written.
+ *
+ * @param buf
+ *     The buffer of data to write to the given guac_socket.
+ *
+ * @param count
+ *     The number of bytes within the given buffer.
+ *
+ * @return
+ *     The number of bytes written, which will be exactly the size of the given
+ *     buffer, or a negative value if an error occurs.
+ */
+ssize_t guac_socket_wsa_write(guac_socket* socket,
+        const void* buf, size_t count) {
+
+    guac_socket_wsa_data* data = (guac_socket_wsa_data*) socket->data;
+    const char* buffer = buf;
+
+    /* Write until completely written */
+    while (count > 0) {
+
+        int retval = send(data->sock, buffer, count, 0);
+
+        /* Record errors in guac_error */
+        if (retval < 0) {
+            guac_error = GUAC_STATUS_SEE_ERRNO;
+            guac_error_message = "Error writing data to socket";
+            return retval;
+        }
+
+        /* Advance buffer as data retval */
+        buffer += retval;
+        count  -= retval;
+
+    }
+
+    return 0;
+
+}
+
+/**
+ * Attempts to read from the underlying SOCKET handle of the given guac_socket,
+ * populating the given buffer.
+ *
+ * @param socket
+ *     The guac_socket being read from.
+ *
+ * @param buf
+ *     The arbitrary buffer which we must populate with data.
+ *
+ * @param count
+ *     The maximum number of bytes to read into the buffer.
+ *
+ * @return
+ *     The number of bytes read, or -1 if an error occurs.
+ */
+static ssize_t guac_socket_wsa_read_handler(guac_socket* socket,
+        void* buf, size_t count) {
+
+    guac_socket_wsa_data* data = (guac_socket_wsa_data*) socket->data;
+
+    /* Read from socket */
+    int retval = recv(data->sock, buf, count, 0);
+
+    /* Record errors in guac_error */
+    if (retval < 0) {
+        guac_error = GUAC_STATUS_SEE_ERRNO;
+        guac_error_message = "Error reading data from socket";
+    }
+
+    return retval;
+
+}
+
+/**
+ * Flushes the contents of the output buffer of the given socket immediately,
+ * without first locking access to the output buffer. This function must ONLY
+ * be called if the buffer lock has already been acquired.
+ *
+ * @param socket
+ *     The guac_socket to flush.
+ *
+ * @return
+ *     Zero if the flush operation was successful, non-zero otherwise.
+ */
+static ssize_t guac_socket_wsa_flush(guac_socket* socket) {
+
+    guac_socket_wsa_data* data = (guac_socket_wsa_data*) socket->data;
+
+    /* Flush remaining bytes in buffer */
+    if (data->written > 0) {
+
+        /* Write ALL bytes in buffer immediately */
+        if (guac_socket_wsa_write(socket, data->out_buf, data->written))
+            return 1;
+
+        data->written = 0;
+    }
+
+    return 0;
+
+}
+
+/**
+ * Flushes the internal buffer of the given guac_socket, writing all data
+ * to the underlying SOCKET handle.
+ *
+ * @param socket
+ *     The guac_socket to flush.
+ *
+ * @return
+ *     Zero if the flush operation was successful, non-zero otherwise.
+ */
+static ssize_t guac_socket_wsa_flush_handler(guac_socket* socket) {
+
+    int retval;
+    guac_socket_wsa_data* data = (guac_socket_wsa_data*) socket->data;
+
+    /* Acquire exclusive access to buffer */
+    pthread_mutex_lock(&(data->buffer_lock));
+
+    /* Flush contents of buffer */
+    retval = guac_socket_wsa_flush(socket);
+
+    /* Relinquish exclusive access to buffer */
+    pthread_mutex_unlock(&(data->buffer_lock));
+
+    return retval;
+
+}
+
+/**
+ * Writes the contents of the buffer to the output buffer of the given socket,
+ * flushing the output buffer as necessary, without first locking access to the
+ * output buffer. This function must ONLY be called if the buffer lock has
+ * already been acquired.
+ *
+ * @param socket
+ *     The guac_socket to write the given buffer to.
+ *
+ * @param buf
+ *     The buffer to write to the given socket.
+ *
+ * @param count
+ *     The number of bytes in the given buffer.
+ *
+ * @return
+ *     The number of bytes written, or a negative value if an error occurs
+ *     during write.
+ */
+static ssize_t guac_socket_wsa_write_buffered(guac_socket* socket,
+        const void* buf, size_t count) {
+
+    size_t original_count = count;
+    const char* current = buf;
+    guac_socket_wsa_data* data = (guac_socket_wsa_data*) socket->data;
+
+    /* Append to buffer, flush if necessary */
+    while (count > 0) {
+
+        int chunk_size;
+        int remaining = sizeof(data->out_buf) - data->written;
+
+        /* If no space left in buffer, flush and retry */
+        if (remaining == 0) {
+
+            /* Abort if error occurs during flush */
+            if (guac_socket_wsa_flush(socket))
+                return -1;
+
+            /* Retry buffer append */
+            continue;
+
+        }
+
+        /* Calculate size of chunk to be written to buffer */
+        chunk_size = count;
+        if (chunk_size > remaining)
+            chunk_size = remaining;
+
+        /* Update output buffer */
+        memcpy(data->out_buf + data->written, current, chunk_size);
+        data->written += chunk_size;
+
+        /* Update provided buffer */
+        current += chunk_size;
+        count   -= chunk_size;
+
+    }
+
+    /* All bytes have been written, possibly some to the internal buffer */
+    return original_count;
+
+}
+
+/**
+ * Appends the provided data to the internal buffer for future writing. The
+ * actual write attempt will occur only upon flush, or when the internal buffer
+ * is full.
+ *
+ * @param socket
+ *     The guac_socket being write to.
+ *
+ * @param buf
+ *     The arbitrary buffer containing the data to be written.
+ *
+ * @param count
+ *     The number of bytes contained within the buffer.
+ *
+ * @return
+ *     The number of bytes written, or -1 if an error occurs.
+ */
+static ssize_t guac_socket_wsa_write_handler(guac_socket* socket,
+        const void* buf, size_t count) {
+
+    int retval;
+    guac_socket_wsa_data* data = (guac_socket_wsa_data*) socket->data;
+    
+    /* Acquire exclusive access to buffer */
+    pthread_mutex_lock(&(data->buffer_lock));
+
+    /* Write provided data to buffer */
+    retval = guac_socket_wsa_write_buffered(socket, buf, count);
+
+    /* Relinquish exclusive access to buffer */
+    pthread_mutex_unlock(&(data->buffer_lock));
+
+    return retval;
+
+}
+
+/**
+ * Waits for data on the underlying SOCKET handle of the given socket to
+ * become available such that the next read operation will not block.
+ *
+ * @param socket
+ *     The guac_socket to wait for.
+ *
+ * @param usec_timeout
+ *     The maximum amount of time to wait for data, in microseconds, or -1 to
+ *     potentially wait forever.
+ *
+ * @return
+ *     A positive value on success, zero if the timeout elapsed and no data is
+ *     available, or a negative value if an error occurs.
+ */
+static int guac_socket_wsa_select_handler(guac_socket* socket,
+        int usec_timeout) {
+
+    guac_socket_wsa_data* data = (guac_socket_wsa_data*) socket->data;
+
+    fd_set sockets;
+    struct timeval timeout;
+    int retval;
+
+    /* Initialize fd_set with single underlying socket handle */
+    FD_ZERO(&sockets);
+    FD_SET(data->sock, &sockets);
+
+    /* No timeout if usec_timeout is negative */
+    if (usec_timeout < 0)
+        retval = select(0, &sockets, NULL, NULL, NULL);
+
+    /* Handle timeout if specified */
+    else {
+        timeout.tv_sec  = usec_timeout / 1000000;
+        timeout.tv_usec = usec_timeout % 1000000;
+        retval = select(0, &sockets, NULL, NULL, &timeout);
+    }
+
+    /* Properly set guac_error */
+    if (retval <  0) {
+        guac_error = GUAC_STATUS_SEE_ERRNO;
+        guac_error_message = "Error while waiting for data on socket";
+    }
+
+    if (retval == 0) {
+        guac_error = GUAC_STATUS_TIMEOUT;
+        guac_error_message = "Timeout while waiting for data on socket";
+    }
+
+    return retval;
+
+}
+
+/**
+ * Frees all implementation-specific data associated with the given socket, but
+ * not the socket object itself.
+ *
+ * @param socket
+ *     The guac_socket whose associated data should be freed.
+ *
+ * @return
+ *     Zero if the data was successfully freed, non-zero otherwise. This
+ *     implementation always succeeds, and will always return zero.
+ */
+static int guac_socket_wsa_free_handler(guac_socket* socket) {
+
+    guac_socket_wsa_data* data = (guac_socket_wsa_data*) socket->data;
+
+    /* Destroy locks */
+    pthread_mutex_destroy(&(data->socket_lock));
+    pthread_mutex_destroy(&(data->buffer_lock));
+
+    /* Close socket */
+    closesocket(data->sock);
+
+    free(data);
+    return 0;
+
+}
+
+/**
+ * Acquires exclusive access to the given socket.
+ *
+ * @param socket
+ *     The guac_socket to which exclusive access is required.
+ */
+static void guac_socket_wsa_lock_handler(guac_socket* socket) {
+
+    guac_socket_wsa_data* data = (guac_socket_wsa_data*) socket->data;
+
+    /* Acquire exclusive access to socket */
+    pthread_mutex_lock(&(data->socket_lock));
+
+}
+
+/**
+ * Relinquishes exclusive access to the given socket.
+ *
+ * @param socket
+ *     The guac_socket to which exclusive access is no longer required.
+ */
+static void guac_socket_wsa_unlock_handler(guac_socket* socket) {
+
+    guac_socket_wsa_data* data = (guac_socket_wsa_data*) socket->data;
+
+    /* Relinquish exclusive access to socket */
+    pthread_mutex_unlock(&(data->socket_lock));
+
+}
+
+guac_socket* guac_socket_open_wsa(SOCKET sock) {
+
+    pthread_mutexattr_t lock_attributes;
+
+    /* Allocate socket and associated data */
+    guac_socket* socket = guac_socket_alloc();
+    guac_socket_wsa_data* data = malloc(sizeof(guac_socket_wsa_data));
+
+    /* Store socket as socket data */
+    data->sock = sock;
+    data->written = 0;
+    socket->data = data;
+
+    pthread_mutexattr_init(&lock_attributes);
+    pthread_mutexattr_setpshared(&lock_attributes, PTHREAD_PROCESS_SHARED);
+
+    /* Init locks */
+    pthread_mutex_init(&(data->socket_lock), &lock_attributes);
+    pthread_mutex_init(&(data->buffer_lock), &lock_attributes);
+    
+    /* Set read/write handlers */
+    socket->read_handler   = guac_socket_wsa_read_handler;
+    socket->write_handler  = guac_socket_wsa_write_handler;
+    socket->select_handler = guac_socket_wsa_select_handler;
+    socket->lock_handler   = guac_socket_wsa_lock_handler;
+    socket->unlock_handler = guac_socket_wsa_unlock_handler;
+    socket->flush_handler  = guac_socket_wsa_flush_handler;
+    socket->free_handler   = guac_socket_wsa_free_handler;
+
+    return socket;
+
+}
+