# Weaver

Coming soon.

## Commands
Weaver and the C code that is calling it communicate using these
commands. Commands are returned as a string. The first four characters
of the string are guaranteed to contain a four-letter command code.
The rest of the string depends on the command.

### DONE
   This is always the last command sent. It has no additional data. (It always
literally consists of the string "DONE".) No more commands will be delivered.

### ERRR
   This represents a fatal error processing the request. No more commands
will be delivered. The content of the string after the first four characters
is an error message.

### RBOD
   This indicates to the caller that the Go code wishes to read the request
body. The caller must respond to this command by sending the request
body in chunks, and must set the "last" value of the last chunk.
There is no additional data.

### WHDR
   This replaces the headers of the message. The headers to be replaced
are the request headers unless SWTCH has been sent, in which case they are
the response headers.

### WURI
   This replaces the URI of the target response. If the URL is a full URI
(that is it starts with a protocol) then the caller should ensure that the
target server is changed to the new value. Otherwise, the caller should
replace only the path. This command will never be sent after a SWCH.

### WSTA
  This replaces the status code in a response message.

### SWCH
   This indicates a switch from running in proxy mode to generating a
request entirely. Once SWCH is sent, subsequent calls to WHDR and WBOD
indicate data that should be returned directly to the caller, rather
than continuing to proxy the data.

### WBOD
   This is a chunk of data that will replace the body. Additional calls
to WBOD may follow. A call to DONE indicates that the write is complete.
If SWCH was previously sent, then the body represents the response body
to send the client. Otherwise it replaces the request body that will
be forwarded to the target.

## Message formats

### Error

The ERRR message consists of the four characters "ERRR" followed immediately
by the text of an error message in UTF-8 encoding.

### Headers

The WHDR message consists of the four characters "WHDR" followed immediately by
header / value pairs. Each header / value pair is separated by a single newline
( \n ). Within the pairs, each header consists of a set of characters followed
by a colon ( : ), and optional white space. The rest of the line after the
optional whitespace is the value of the header. The same header may appear
multiple times in the output, denoting multiple values.

### URI

The SURI message consists of the four characters "WURI" followed immediately
by the new URI.

### Response Switch

The SWCH message consists of the four characters "SWCH" followed immediately
by the response code, represented as a UTF-8 encoded string in base 10.

### Status Code

The WSTA message consists of the four characters "WSTA" followed immediately
by the new HTTP status code, represented as a UTF-8 encoded string in base 10.

### Body Chunk

The WBOD message returns the unique ID of a chunk of response data.
It consists of the four characters WBOD, followed immediately by the
chunk ID in hexadecimal format. The caller should use the various
"chunk" C API calls to retrieve the chunk, and then free the storage.