From 62bcedced863a9c4ecc3601638635dfe172a9130 Mon Sep 17 00:00:00 2001
From: Matt Colyer
Date: Mon, 4 Aug 2008 23:41:56 -0700
Subject: Zack's C. rewrite of usbmux (with a few additions by Matt Colyer).

---
 src/usbmux.c | 251 +++++++++++++++++++++++++++++++++++++++++++----------------
 1 file changed, 186 insertions(+), 65 deletions(-)

(limited to 'src/usbmux.c')

diff --git a/src/usbmux.c b/src/usbmux.c
index bdeea09..043f8af 100644
--- a/src/usbmux.c
+++ b/src/usbmux.c
@@ -29,6 +29,9 @@
 
 extern int debug;
 
+static usbmux_connection **connlist = NULL;
+static int connections = 0;
+
 usbmux_tcp_header *new_mux_packet(uint16 s_port, uint16 d_port) {
 	usbmux_tcp_header *conn = (usbmux_tcp_header*)malloc(sizeof(usbmux_tcp_header));
 	conn->type = htonl(6);
@@ -54,6 +57,47 @@ usbmux_version_header *version_header() {
 	return version;
 }
 
+
+// Maintenance functions.
+
+/* delete_connection(connection)
+ * 	connection: the connection to delete from the tracking list.
+ * Removes a connection from the list of connections made.
+ * The list of connections is necessary for buffering.
+ */
+
+void delete_connection(usbmux_connection *connection) {
+	usbmux_connection **newlist = (usbmux_connection**)malloc(sizeof(usbmux_connection*) * (connections - 1));
+	int i = 0, j = 0;
+	for (i = 0; i < connections; i++) {
+		if (connlist[i] == connection) continue;
+		else {
+			newlist[j] = connlist[i];
+			j++;
+		}
+	}
+	free(connlist);
+	connlist = newlist;
+	connections--;
+	if (connection->recv_buffer) free(connection->recv_buffer);
+	if (connection->header) free(connection->header);
+	connection->r_len = 0;
+	free(connection);
+}
+
+/* add_connection(connection)
+ * 	connection: the connection to add to the global list of connections.
+ * Adds a connection to the list of connections made.
+ * The connection list is necessary for buffering.
+ */
+
+void add_connection(usbmux_connection *connection) {
+	usbmux_connection **newlist = (usbmux_connection**)realloc(connlist, sizeof(usbmux_connection*) * (connections+1));
+	newlist[connections] = connection;
+	connlist = newlist;
+	connections++;
+}
+
 /* mux_connect(phone, s_port, d_port)
  * This is a higher-level USBMuxTCP-type function.
  * 	phone: the iPhone to initialize a connection on.
@@ -64,27 +108,33 @@ usbmux_version_header *version_header() {
  * Returns a mux TCP header for the connection which is used for tracking and data transfer.
  */ 
 
-usbmux_tcp_header *mux_connect(iPhone *phone, uint16 s_port, uint16 d_port) {
+usbmux_connection *mux_connect(iPhone *phone, uint16 s_port, uint16 d_port) {
 	if (!phone || !s_port || !d_port) return NULL;
 	int bytes = 0;
 	// Initialize connection stuff
-	usbmux_tcp_header *new_connection;
-	new_connection = new_mux_packet(s_port, d_port);
+	usbmux_connection *new_connection = (usbmux_connection*)malloc(sizeof(usbmux_connection));
+	new_connection->header = new_mux_packet(s_port, d_port);
 	usbmux_tcp_header *response;
 	response = (usbmux_tcp_header*)malloc(sizeof(usbmux_tcp_header));
 	// blargg
-	if (new_connection) {
-		new_connection->tcp_flags = 0x02;
-		new_connection->length = htonl(new_connection->length);
-		new_connection->length16 = htons(new_connection->length16);
+	if (new_connection && new_connection->header) {
+		new_connection->header->tcp_flags = 0x02;
+		new_connection->header->length = htonl(new_connection->header->length);
+		new_connection->header->length16 = htons(new_connection->header->length16);
 		
-		if (send_to_phone(phone, (char*)new_connection, sizeof(*new_connection)) >= 0) {
+		if (send_to_phone(phone, (char*)new_connection->header, sizeof(usbmux_tcp_header)) >= 0) {
 			bytes = recv_from_phone(phone, (char*)response, sizeof(*response));
 			if (response->tcp_flags != 0x12) return NULL;
 			else {
-				new_connection->tcp_flags = 0x10;
-				new_connection->scnt = 1;
-				new_connection->ocnt = 1;
+				if (debug) printf("mux_connect: connection success\n");
+				new_connection->header->tcp_flags = 0x10;
+				new_connection->header->scnt = 1;
+				new_connection->header->ocnt = 1;
+				add_connection(new_connection);
+				new_connection->phone = phone;
+				new_connection->recv_buffer = NULL;
+				new_connection->r_len = 0;
+				add_connection(new_connection);
 				return new_connection;
 			}
 		} else {
@@ -103,23 +153,24 @@ usbmux_tcp_header *mux_connect(iPhone *phone, uint16 s_port, uint16 d_port) {
  * 
  * Doesn't return anything; WILL FREE THE CONNECTION'S MEMORY!!!
  */
-void mux_close_connection(iPhone *phone, usbmux_tcp_header *connection) {
-	if (!phone || !connection) return;
+
+void mux_close_connection(usbmux_connection *connection) {
+	if (!connection || !connection->phone) return;
 	
-	connection->tcp_flags = 0x04;
-	connection->scnt = htonl(connection->scnt);
-	connection->ocnt = htonl(connection->ocnt);
+	connection->header->tcp_flags = 0x04;
+	connection->header->scnt = htonl(connection->header->scnt);
+	connection->header->ocnt = htonl(connection->header->ocnt);
 	int bytes = 0;
 	
-	bytes = usb_bulk_write(phone->device, BULKOUT, (char*)connection, sizeof(*connection), 800);
+	bytes = usb_bulk_write(connection->phone->device, BULKOUT, (char*)connection->header, sizeof(usbmux_tcp_header), 800);
 	if(debug && bytes < 0)
 		printf("mux_close_connection(): when writing, libusb gave me the error: %s\n", usb_strerror());
 
-	bytes = usb_bulk_read(phone->device, BULKIN, (char*)connection, sizeof(*connection), 800);
+	bytes = usb_bulk_read(connection->phone->device, BULKIN, (char*)connection->header, sizeof(usbmux_tcp_header), 800);
 	if(debug && bytes < 0)
 		printf("get_iPhone(): when reading, libusb gave me the error: %s\n", usb_strerror());
 	
-	free(connection);
+	delete_connection(connection);
 }
 
 /* mux_send(phone, connection, data, datalen)
@@ -131,40 +182,46 @@ void mux_close_connection(iPhone *phone, usbmux_tcp_header *connection) {
  * 
  * Returns number of bytes sent, minus the header (28), or -1 on error.
  */
-int mux_send(iPhone *phone, usbmux_tcp_header *connection, char *data, uint32 datalen) {
-	if (!phone || !connection || !data || datalen == 0) return -1;
+int mux_send(usbmux_connection *connection, const char *data, uint32 datalen) {
+	if (!connection->phone || !connection || !data || datalen == 0) return -1;
 	// connection->scnt and connection->ocnt should already be in host notation...
 	// we don't need to change them juuuust yet. 
 	int bytes = 0;
 	if (debug) printf("mux_send(): client wants to send %i bytes\n", datalen);
-	char *buffer = (char*)malloc(sizeof(*connection) + datalen + 2); // allow 2 bytes of safety padding
+	char *buffer = (char*)malloc(sizeof(usbmux_tcp_header) + datalen + 2); // allow 2 bytes of safety padding
 	// Set the length and pre-emptively htonl/htons it
-	connection->length = htonl(sizeof(*connection) + datalen);
-	connection->length16 = htons(sizeof(*connection) + datalen);
+	connection->header->length = htonl(sizeof(usbmux_tcp_header) + datalen);
+	connection->header->length16 = htons(sizeof(usbmux_tcp_header) + datalen);
 	
 	// Put scnt and ocnt into big-endian notation
-	connection->scnt = htonl(connection->scnt);
-	connection->ocnt = htonl(connection->ocnt);
+	connection->header->scnt = htonl(connection->header->scnt);
+	connection->header->ocnt = htonl(connection->header->ocnt);
 	// Concatenation of stuff in the buffer.
-	memcpy(buffer, connection, sizeof(*connection));
-	memcpy(buffer+sizeof(*connection)/*+sizeof(datalen)*/, data, datalen);
+	memcpy(buffer, connection->header, sizeof(usbmux_tcp_header));
+	memcpy(buffer+sizeof(usbmux_tcp_header), data, datalen);
 	
 	// We have a buffer full of data, we should now send it to the phone.
-	if (debug) printf("actually sending %i bytes of data at %x\n", sizeof(*connection)+datalen, buffer);
+	if (debug) printf("actually sending %i bytes of data at %x\n", sizeof(usbmux_tcp_header)+datalen, buffer);
 
 	
-	bytes = send_to_phone(phone, buffer, sizeof(*connection)+datalen);
-	
+	bytes = send_to_phone(connection->phone, buffer, sizeof(usbmux_tcp_header)+datalen);
+	if (debug) printf("mux_send: sent %i bytes!\n", bytes);
 	// Now that we've sent it off, we can clean up after our sloppy selves.
-	free(buffer);
+	if (debug) {
+		FILE *packet = fopen("packet", "a+");
+		fwrite(buffer, 1, bytes, packet);
+		fclose(packet);
+		printf("\n");
+	}
 	
+	if (buffer) free(buffer);
 	// Re-calculate scnt and ocnt
-	connection->scnt = ntohl(connection->scnt) + datalen;
-	connection->ocnt = ntohl(connection->ocnt);
+	connection->header->scnt = ntohl(connection->header->scnt) + datalen;
+	connection->header->ocnt = ntohl(connection->header->ocnt);
 	
 	// Revert lengths
-	connection->length = ntohl(connection->length);
-	connection->length16 = ntohs(connection->length16);
+	connection->header->length = ntohl(connection->header->length);
+	connection->header->length16 = ntohs(connection->header->length16);
 	
 	// Now return the bytes.
 	if (bytes < sizeof(*connection)+datalen) {
@@ -186,39 +243,103 @@ int mux_send(iPhone *phone, usbmux_tcp_header *connection, char *data, uint32 da
  * Returns: how many bytes were read, or -1 if something bad happens.
  */
 
-int mux_recv(iPhone *phone, usbmux_tcp_header *connection, char *data, uint32 datalen) {
-	char *buffer = (char*)malloc(sizeof(*connection) + sizeof(datalen) + datalen);
-	int bytes = 0, my_datalen = 0;
+int mux_recv(usbmux_connection *connection, char *data, uint32 datalen) {
+	/*
+	 * Order of operation:
+	 * 1.) Check if the connection has a pre-received buffer.
+	 * 2.) If so, fill data with the buffer, as much as needed.
+	 * 	a.) Return quickly if the buffer has enough
+	 * 	b.) If the buffer is only part of the datalen, get the rest of datalen (and if we can't, just return)
+	 * 3.) If not, receive directly from the phone. 
+	 * 	a.) Check incoming packet's ports. If proper, follow proper buffering and receiving operation.
+	 * 	b.) If not, find the connection the ports belong to and fill that connection's buffer, then return mux_recv with the same args to try again.
+	 */
 	if (debug) printf("mux_recv: datalen == %i\n", datalen);
-	bytes = recv_from_phone(phone, buffer, sizeof(*connection) + datalen);
-	if (debug) printf("mux_recv: bytes == %i\n", bytes);
-	if (bytes < datalen) {
-		if (bytes < 28) {
-			// if they didn't do that annoying thing, something else mighta happened.
-			if (debug) printf("mux_recv: bytes too low anyway!\n");
-			free(buffer);
-			return -1;
-		} else if (bytes == 28) { // no data...
-			free(buffer);
-			return 0;
-		} else { // bytes > 28
-			my_datalen = ntohl(buffer[4]) - 28;
-			connection->ocnt += my_datalen;
-			memcpy(data, buffer+28, bytes - 28);
-			free(buffer);
-			if (debug) printf("mux_recv: bytes received: %i\n", bytes - 28);
-			return bytes - 28;
+	int bytes = 0, i = 0, complex = 0, offset = 0;
+	char *buffer = NULL;
+	usbmux_tcp_header *header = NULL;
+		
+	if (connection->recv_buffer) {
+		if (connection->r_len >= datalen) {
+			memcpy(data, connection->recv_buffer, datalen);
+			if (connection->r_len == datalen) {
+				// reset everything
+				free(connection->recv_buffer);
+				connection->r_len = 0;
+				connection->recv_buffer = NULL;
+			} else {
+				buffer = (char*)malloc(sizeof(char) * (connection->r_len - datalen));
+				memcpy(buffer, connection->recv_buffer+datalen, (connection->r_len - datalen));
+				connection->r_len -= datalen;
+				free(connection->recv_buffer);
+				connection->recv_buffer = buffer;
+			}
+			
+			// Since we were able to fill the data straight from our buffer, we can just return datalen. See 2a above.
+			return datalen;
+		} else {
+			memcpy(data, connection->recv_buffer, connection->r_len);
+			free(connection->recv_buffer); // don't need to deal with anymore, but...
+			offset = connection->r_len; // see #2b, above
+			connection->r_len = 0;
 		}
-	} else {// all's good, they didn't do anything bonky.
-		my_datalen = ntohl(buffer[4]) - 28; 
-		connection->ocnt += my_datalen;
-		if (bytes == (datalen+28)) memcpy(data, buffer+28, datalen); 
-		else if (bytes == datalen) memcpy(data, buffer+28, datalen-28);
+	} // End of what to do if we have a pre-buffer. See #1 and #2 above. 
+	
+	buffer = (char*)malloc(sizeof(char) * 131072); // make sure we get enough ;)
+	
+	// See #3.
+	bytes = recv_from_phone(connection->phone, buffer, 131072);
+	if (bytes < 28) {
+		free(buffer);
+		if (debug) printf("mux_recv: Did not even get the header.\n");
+		return -1;
+	}
+	
+	header = (usbmux_tcp_header*)buffer;
+	if (header->sport != connection->header->dport || header->dport != connection->header->sport) {
+		// Ooooops -- we got someone else's packet.
+		// We gotta stick it in their buffer. (Take that any old way you want ;) )
+		for (i = 0; i < connections; i++) {
+			if (connlist[i]->header->sport == header->dport && connlist[i]->header->dport == header->sport) {
+				// we have a winner.
+				connlist[i]->r_len += bytes - 28;
+				connlist[i]->recv_buffer = (char*)realloc(connlist[i]->recv_buffer, sizeof(char) * connection->r_len); // grow their buffer
+				complex = connlist[i]->r_len - (bytes - 28);
+				memcpy(connlist[i]->recv_buffer+complex, buffer+28, bytes-28); // paste into their buffer
+				connlist[i]->header->ocnt += bytes-28;
+			}
+		}
+		// If it wasn't ours, it's been handled by this point... or forgotten.
+		// Free our buffer and continue.
+		free(buffer);
+		buffer = NULL;
+		return mux_recv(connection, data, datalen); // recurse back in to try again
+	}
+
+	// The packet was absolutely meant for us if it hits this point.
+	// The pre-buffer has been taken care of, so, again, if we're at this point we have to read from the phone.
+	
+	if ((bytes-28) > datalen) {
+		// Copy what we need into the data, buffer the rest because we can.
+		memcpy(data+offset, buffer+28, datalen); // data+offset: see #2b, above
+		complex = connection->r_len + (bytes-28) - datalen;
+		connection->recv_buffer = (char*)realloc(connection->recv_buffer, (sizeof(char) * complex));
+		connection->r_len = complex;
+		complex = connection->r_len - (bytes-28) - datalen;
+		memcpy(connection->recv_buffer+complex, buffer+28+datalen, (bytes-28) - datalen);
+		free(buffer);
+		connection->header->ocnt += bytes-28;
+		return datalen;
+	} else {
+		// Fill the data with what we have, and just return.
+		memcpy(data+offset, buffer+28, bytes-28); // data+offset: see #2b, above
+		connection->header->ocnt += bytes-28;
 		free(buffer);
-		if (debug) printf("mux_recv: bytes received: %i\n", bytes - 28);
-		return bytes - 28;
+		return (bytes-28);
 	}
 	
-	return bytes;
+	// If we get to this point, 'tis probably bad.
+	if (debug) printf("mux_recv: Heisenbug: bytes and datalen not matching up\n");
+	return -1;
 }
 
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