commit b4d17e5b2a2054c888ad26cc2aeb603bde2acb30 Author: David Fifield david@bamsoftware.com Date: Sun Aug 21 02:06:22 2011 -0700
Lowercase "flash" when we're not specifically talking about Adobe Flash. --- README | 8 ++++---- design.txt | 46 +++++++++++++++++++++++----------------------- facilitator.py | 2 +- 3 files changed, 28 insertions(+), 28 deletions(-)
diff --git a/README b/README index cd6b7dd..c0c8f6f 100644 --- a/README +++ b/README @@ -1,15 +1,15 @@ == Introduction
This is a set of tools that make it possible to connect Tor through an -Adobe Flash proxy running on another computer. The Flash proxy can be +browser-based proxy running on another computer. The flash proxy can be run just by opening a web page in a computer that has Flash Player installed.
There are five main parts. Our terminology for each part is in quotes. 1. The Tor "client," running on someone's localhost. -2. A "connector," which waits for connections from the Flash proxy and +2. A "connector," which waits for connections from the flash proxy and the Tor client, and joins them together. -3. A Flash "proxy," running in someone's web browser. This piece is +3. A "flash proxy," running in someone's web browser. This piece is called swfcat because it is like a netcat implemented in Flash. 4. A "facilitator," a pseudo-HTTP server that keeps a list of clients that want a connection, and hands them out to proxies. @@ -139,7 +139,7 @@ Clients register with the facilitator by sending an HTTP message: POST / HTTP/1.0\r\n \r\n client=<ip-addr/rtmfp-id> -The Flash proxy also gets a client address over HTTP: +The flash proxy also gets a client address over HTTP: GET / HTTP/1.0\r\n \r\n The server sends back address specifications of a client and a relay in diff --git a/design.txt b/design.txt index 9b79724..f33468c 100644 --- a/design.txt +++ b/design.txt @@ -1,4 +1,4 @@ -Design of Flash proxies +Design of flash proxies
0. Problem statement
@@ -13,7 +13,7 @@ Design of Flash proxies that themselves can reach the Tor network. We call this subset the unrestricted Internet.
- A browser-based proxy (Flash proxy), running in a web page in the + A browser-based proxy (flash proxy), running in a web page in the unrestricted Internet, proxies connections between the restricted Internet and the Tor network. These proxies are expected to be temporary and short-lived, but their number will be great enough that @@ -23,7 +23,7 @@ Design of Flash proxies networking technologies is complicated by restrictions that prevent it being a straightforward proxy. Chief among these is the lack of listening sockets. Flash and, for example, WebSockets, can only - initiate outgoing connections, not receive incoming ones. The Flash + initiate outgoing connections, not receive incoming ones. The flash proxy can only connect to external hosts by connecting directly to them. The other significant restriction is that the proxy cannot connect to just any destination: Adobe Flash player requires the @@ -33,15 +33,15 @@ Design of Flash proxies
2. Components
- Conceptually, each Flash proxy is nothing more than a simple proxy, + Conceptually, each flash proxy is nothing more than a simple proxy, which accepts connections from a client and forwards data to a server. But because of the limited networking facilities available to an in-browser application, several other pieces are needed.
1. Tor client: Is just ordinary Tor with a special configuration to - allow it to connect through a Flash proxy. It advertises its need + allow it to connect through a flash proxy. It advertises its need for a connection the the facilitator, and communicates with the - Flash proxy through the connector. + flash proxy through the connector. 2. Connector: Runs on the same computer as the Tor client. It opens one socket to the Internet and another to localhost. It waits for a connection on both sockets, then starts proxying data between them. @@ -50,13 +50,13 @@ Design of Flash proxies startup, the connector informs the facilitator that it is waiting for a connection. 3. Flash proxy: Runs in someone's browser, in an uncensored region of - the Internet. The Flash proxy first connects to the facilitator to + the Internet. The flash proxy first connects to the facilitator to get a client registration. It then makes two outgoing connections, one to a Tor relay and one to a waiting Tor client, and starts proxying data between them. 4. Facilitator: Keeps track of client registrations and hands them out to clients. It is capable of receiving client registrations in a - variety of ways. It sends registrations to Flash proxies over HTTP. + variety of ways. It sends registrations to flash proxies over HTTP. The facilitator is responsible for matching clients to proxies in a reasonable manner. 5. Tor relay: An ordinary Tor relay with no special configuration @@ -68,15 +68,15 @@ Design of Flash proxies 2. The restricted user starts Tor, which makes a SOCKS connection to the connector. 3. The connector notifies the facilitator that it needs a connection. - 4. An unrestricted user opens the web page containing the Flash proxy. - 5. The Flash proxy connects to the facilitator and asks for a client. + 4. An unrestricted user opens the web page containing the flash proxy. + 5. The flash proxy connects to the facilitator and asks for a client. 6. The facilitator sends one of its client registrations to the proxy. - 7. The Flash proxy connects to a Tor relay and to the waiting client + 7. The flash proxy connects to a Tor relay and to the waiting client connector. - 8. The connector receives the Flash proxy's connection and begins + 8. The connector receives the flash proxy's connection and begins relaying data between it and the Tor relay.
- Later, the Flash proxy may go offline. Assuming that another Flash + Later, the flash proxy may go offline. Assuming that another flash proxy is available, it will receive the same client's address from the facilitator, and the local Tor client will reconnect to the client through it. @@ -89,19 +89,19 @@ Design of Flash proxies Bridge 127.0.0.1:9001 Socks4Proxy 127.0.0.1:9001 The address given for the "Bridge" option is actually irrelevant. The - connector will ignore it and connect (through the Flash proxy) to a + connector will ignore it and connect (through the flash proxy) to a Tor relay. The Tor client does not have control of its first hop.
6. Behavior of the connector
The connector serves two purposes: It sends a registration message to - the facilitator and it carries data between a Flash proxy and the + the facilitator and it carries data between a flash proxy and the local Tor client.
On startup, the connector sends a registration message to the facilitator, informing the facilitator that it is waiting for a connection. The facilitator will later hand this registration to a - Flash proxy. The registration message is an HTTP POST request of the + flash proxy. The registration message is an HTTP POST request of the form:
POST / HTTP/1.0 @@ -121,19 +121,19 @@ Design of Flash proxies external address.
The connector solves the impedance mismatch between the Tor client and - the Flash proxy, both of which want to make outgoing connections to + the flash proxy, both of which want to make outgoing connections to the other. The connector sits in between, listens for connections from both ends, and matches them together. The remote socket listens on port 9000 and the local on port 9001.
The connector can serve a crossdomain policy in response to a - crossdomain request, allowing the Flash proxy to connect. On the local + crossdomain request, allowing the flash proxy to connect. On the local side, it acts as a SOCKS proxy (albeit one that always goes to the same destination).
-7. Behavior of the Flash proxy +7. Behavior of the flash proxy
- The Flash proxy polls the facilitator for client registrations. When + The flash proxy polls the facilitator for client registrations. When it receives a registration, it opens one connection to the given Tor relay, one to the given client, and begin proxying data between them.
@@ -154,7 +154,7 @@ Design of Flash proxies The facilitator keeps the HTTP session alive and does not send a registration until one is available.
- The Flash proxy may serve more than one relay–client pair at once. + The flash proxy may serve more than one relay–client pair at once.
8. Behavior of the facilitator
@@ -163,11 +163,11 @@ Design of Flash proxies facilitator listens on port 9002.
In the current implementation, the facilitator forgets a client - registration after giving it to a Flash proxy. The client must + registration after giving it to a flash proxy. The client must re-register if it wants another connection later.
9. Behavior of the Tor relay.
The Tor relay requires no special configuration. It must also be - running a program that serves a crossdomain policy to allow a Flash + running a program that serves a crossdomain policy to allow a flash proxy to connect to it. diff --git a/facilitator.py b/facilitator.py index 86b924c..f7a4ba9 100755 --- a/facilitator.py +++ b/facilitator.py @@ -37,7 +37,7 @@ class options(object): def usage(f = sys.stdout): print >> f, """\ Usage: %(progname)s -r RELAY <OPTIONS> [HOST] [PORT] -Flash bridge facilitator: Register client addresses with HTTP POST requests +Flash proxy facilitator: Register client addresses with HTTP POST requests and serve them out again with HTTP GET. Listen on HOST and PORT, by default %(addr)s %(port)d. -d, --debug don't daemonize, log to stdout.