Documentation updates

+ Add File Transfer Protocols section
* Minor updates

docs/configuration/file-transfer-protocols.md

@@ -0,0 +1,49 @@
+---
+layout: page
+title: File Transfer Protocols
+---
+ENiGMA½ currently relies on external executables for "legacy" file transfer protocols such as X, Y, and ZModem. The `fileTransferProtocols` section of `config.hjson` is used to override defaults, add new handlers, etc. Remember that ENiGMA½ also support modern web (HTTP/HTTPS) downloads!
+
+## File Transfer Protocols
+File transfer protocols are managed via the `fileTransferProtocols` configuration block of `config.hjson`. Each entry defines an **external** protocol that can be used for uploads (recv), downloads (send), or both. Depending on the protocol and handler, batch receiving of files (uploads) may also be available.
+
+### Predefined File Transfer Protocols
+The following file transfer protocols are pre-configured in ENiGMA½ as of this writing. System operators may override or extend this list. PRs are welcome for pre-configured additions!
+
+#### SEXYZ
+[SEXYZ from Synchronet](http://wiki.synchro.net/util:sexyz) offers a nice X, Y, and ZModem implementation including ZModem-8k & works under *nix and Windows based systems. As of this writing, ENiGMA½ is pre-configured to support ZModem-8k, XModem, and YModem using SEXYZ. An x86_64 Linux binary, and hopefully more in the future, [can be downloaded here](http://132.0.0.249/bbs-linux-binaries/).
+
+#### sz/rz
+ZModem-8k is configured using the standard Linux [sz(1)](https://linux.die.net/man/1/sz) and [rz(1)](https://linux.die.net/man/1/rz) binaries. Note that these binaries also support XModem and YModem, and as such adding the configurations to your system should be fairly straight forward.
+
+Generally available as `lrzsz` under Apt or Yum type packaging.
+
+### File Transfer Protocol Configuration
+The following top-level members are available to an external protocol configuration:
+* `name`: Required; Display name of the protocol
+* `type`: Required; Currently must be `external`. This will be expanded upon in the future with built in protocols.
+* `sort`: Optional; Sort key. If not provided, `name` will be used for sorting.
+
+For protocols of type `external` the following members may be defined:
+* `sendCmd`: Required for protocols that can send (allow user downloads); The command/binary to execute.
+* `sendArgs`: Required if using `sendCmd`; An array of arguments. A placeholder of `{fileListPath}` may be used to supply a path to a **file containing** a list of files to send, or `{filePaths}` to supply *1:n* individual file paths to send.
+* `recvCmd`: Required for protocols that can receive (allow user uploads); The command/binary to execute.
+* `recvArgs`: Required if using `recvCmd` and supporting **batch** uploads; An array of arguments. A placeholder of `{uploadDir}` may be used to supply the system provided upload directory. If `{uploadDir}` is not present, the system expects uploaded files to be placed in CWD which will be set to the upload directory. 
+* `recvArgsNonBatch`: Required if using `recvCmd` and supporting non-batch (single file) uploads; A placeholder of `{fileName}` may be supplied to indicate to the protocol what the uploaded file should be named (this will be collected from the user before the upload starts).
+* `escapeTelnet`: Optional; If set to `true`, escape all internal Telnet related codes such as IAC's. This option is required for external protocol handlers such as `sz` and `rz` that do not escape themselves.
+
+#### Example File Transfer Protocol Configuration
+```
+zmodem8kSexyz : {
+	name		: 'ZModem 8k (SEXYZ)',
+	type		: 'external',
+	sort		: 1,
+	external	: {
+		sendCmd				: 'sexyz',
+		sendArgs			: [ '-telnet', '-8', 'sz', '@{fileListPath}' ],
+		recvCmd				: 'sexyz',
+		recvArgs			: [ '-telnet', '-8', 'rz', '{uploadDir}' ],
+		recvArgsNonBatch	: [ '-telnet', '-8', 'rz', '{fileName}' ],
+	}
+}
+```