internals: document CBOR utilization
I spoke with some people at Mozilla about CBOR and they advised me
that we should be careful about the subset of CBOR we use in order
to mitigate security, performance, and compatibility concerns.
This commit establishes a document that attempts to formalize our
use of CBOR.
Its main limitations are on what types are allowed. It explicitly
enumerates which types are supported. Notable missing features
include:
* Indefinite-length arrays and maps
* Text strings (bytes all the way)
* Floats
* Date/time types
* Big integers
* Use of indefinite-length byte strings for map keys, values in
containers.
If we have a need for any of these, we can have a discussion about
them when the time comes.
Differential Revision: https://phab.mercurial-scm.org/D4412
#require no-chg
$ send() {
> hg --verbose debugwireproto --peer raw http://$LOCALIP:$HGPORT/
> }
$ hg init server
$ hg -R server serve -p $HGPORT -d --pid-file hg.pid
$ cat hg.pid > $DAEMON_PIDS
Request to /api fails unless web.apiserver is enabled
$ get-with-headers.py $LOCALIP:$HGPORT api
400 no such method: api
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en-US">
<head>
<link rel="icon" href="/static/hgicon.png" type="image/png" />
<meta name="robots" content="index, nofollow" />
<link rel="stylesheet" href="/static/style-paper.css" type="text/css" />
<script type="text/javascript" src="/static/mercurial.js"></script>
<title>$TESTTMP/server: error</title>
</head>
<body>
<div class="container">
<div class="menu">
<div class="logo">
<a href="https://mercurial-scm.org/">
<img src="/static/hglogo.png" width=75 height=90 border=0 alt="mercurial" /></a>
</div>
<ul>
<li><a href="/shortlog">log</a></li>
<li><a href="/graph">graph</a></li>
<li><a href="/tags">tags</a></li>
<li><a href="/bookmarks">bookmarks</a></li>
<li><a href="/branches">branches</a></li>
</ul>
<ul>
<li><a href="/help">help</a></li>
</ul>
</div>
<div class="main">
<h2 class="breadcrumb"><a href="/">Mercurial</a> </h2>
<h3>error</h3>
<form class="search" action="/log">
<p><input name="rev" id="search1" type="text" size="30" value="" /></p>
<div id="hint">Find changesets by keywords (author, files, the commit message), revision
number or hash, or <a href="/help/revsets">revset expression</a>.</div>
</form>
<div class="description">
<p>
An error occurred while processing your request:
</p>
<p>
no such method: api
</p>
</div>
</div>
</div>
</body>
</html>
[1]
$ get-with-headers.py $LOCALIP:$HGPORT api/
400 no such method: api
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en-US">
<head>
<link rel="icon" href="/static/hgicon.png" type="image/png" />
<meta name="robots" content="index, nofollow" />
<link rel="stylesheet" href="/static/style-paper.css" type="text/css" />
<script type="text/javascript" src="/static/mercurial.js"></script>
<title>$TESTTMP/server: error</title>
</head>
<body>
<div class="container">
<div class="menu">
<div class="logo">
<a href="https://mercurial-scm.org/">
<img src="/static/hglogo.png" width=75 height=90 border=0 alt="mercurial" /></a>
</div>
<ul>
<li><a href="/shortlog">log</a></li>
<li><a href="/graph">graph</a></li>
<li><a href="/tags">tags</a></li>
<li><a href="/bookmarks">bookmarks</a></li>
<li><a href="/branches">branches</a></li>
</ul>
<ul>
<li><a href="/help">help</a></li>
</ul>
</div>
<div class="main">
<h2 class="breadcrumb"><a href="/">Mercurial</a> </h2>
<h3>error</h3>
<form class="search" action="/log">
<p><input name="rev" id="search1" type="text" size="30" value="" /></p>
<div id="hint">Find changesets by keywords (author, files, the commit message), revision
number or hash, or <a href="/help/revsets">revset expression</a>.</div>
</form>
<div class="description">
<p>
An error occurred while processing your request:
</p>
<p>
no such method: api
</p>
</div>
</div>
</div>
</body>
</html>
[1]
Restart server with support for API server
$ killdaemons.py
$ cat > server/.hg/hgrc << EOF
> [experimental]
> web.apiserver = true
> EOF
$ hg -R server serve -p $HGPORT -d --pid-file hg.pid
$ cat hg.pid > $DAEMON_PIDS
/api lists available APIs (empty since none are available by default)
$ send << EOF
> httprequest GET api
> user-agent: test
> EOF
using raw connection to peer
s> GET /api HTTP/1.1\r\n
s> Accept-Encoding: identity\r\n
s> user-agent: test\r\n
s> host: $LOCALIP:$HGPORT\r\n (glob)
s> \r\n
s> makefile('rb', None)
s> HTTP/1.1 200 OK\r\n
s> Server: testing stub value\r\n
s> Date: $HTTP_DATE$\r\n
s> Content-Type: text/plain\r\n
s> Content-Length: 100\r\n
s> \r\n
s> APIs can be accessed at /api/<name>, where <name> can be one of the following:\n
s> \n
s> (no available APIs)\n
$ send << EOF
> httprequest GET api/
> user-agent: test
> EOF
using raw connection to peer
s> GET /api/ HTTP/1.1\r\n
s> Accept-Encoding: identity\r\n
s> user-agent: test\r\n
s> host: $LOCALIP:$HGPORT\r\n (glob)
s> \r\n
s> makefile('rb', None)
s> HTTP/1.1 200 OK\r\n
s> Server: testing stub value\r\n
s> Date: $HTTP_DATE$\r\n
s> Content-Type: text/plain\r\n
s> Content-Length: 100\r\n
s> \r\n
s> APIs can be accessed at /api/<name>, where <name> can be one of the following:\n
s> \n
s> (no available APIs)\n
Accessing an unknown API yields a 404
$ send << EOF
> httprequest GET api/unknown
> user-agent: test
> EOF
using raw connection to peer
s> GET /api/unknown HTTP/1.1\r\n
s> Accept-Encoding: identity\r\n
s> user-agent: test\r\n
s> host: $LOCALIP:$HGPORT\r\n (glob)
s> \r\n
s> makefile('rb', None)
s> HTTP/1.1 404 Not Found\r\n
s> Server: testing stub value\r\n
s> Date: $HTTP_DATE$\r\n
s> Content-Type: text/plain\r\n
s> Content-Length: 33\r\n
s> \r\n
s> Unknown API: unknown\n
s> Known APIs:
Accessing a known but not enabled API yields a different error
$ send << EOF
> httprequest GET api/exp-http-v2-0001
> user-agent: test
> EOF
using raw connection to peer
s> GET /api/exp-http-v2-0001 HTTP/1.1\r\n
s> Accept-Encoding: identity\r\n
s> user-agent: test\r\n
s> host: $LOCALIP:$HGPORT\r\n (glob)
s> \r\n
s> makefile('rb', None)
s> HTTP/1.1 404 Not Found\r\n
s> Server: testing stub value\r\n
s> Date: $HTTP_DATE$\r\n
s> Content-Type: text/plain\r\n
s> Content-Length: 33\r\n
s> \r\n
s> API exp-http-v2-0001 not enabled\n
Restart server with support for HTTP v2 API
$ killdaemons.py
$ cat > server/.hg/hgrc << EOF
> [experimental]
> web.apiserver = true
> web.api.http-v2 = true
> EOF
$ hg -R server serve -p $HGPORT -d --pid-file hg.pid
$ cat hg.pid > $DAEMON_PIDS
/api lists the HTTP v2 protocol as available
$ send << EOF
> httprequest GET api
> user-agent: test
> EOF
using raw connection to peer
s> GET /api HTTP/1.1\r\n
s> Accept-Encoding: identity\r\n
s> user-agent: test\r\n
s> host: $LOCALIP:$HGPORT\r\n (glob)
s> \r\n
s> makefile('rb', None)
s> HTTP/1.1 200 OK\r\n
s> Server: testing stub value\r\n
s> Date: $HTTP_DATE$\r\n
s> Content-Type: text/plain\r\n
s> Content-Length: 96\r\n
s> \r\n
s> APIs can be accessed at /api/<name>, where <name> can be one of the following:\n
s> \n
s> exp-http-v2-0001
$ send << EOF
> httprequest GET api/
> user-agent: test
> EOF
using raw connection to peer
s> GET /api/ HTTP/1.1\r\n
s> Accept-Encoding: identity\r\n
s> user-agent: test\r\n
s> host: $LOCALIP:$HGPORT\r\n (glob)
s> \r\n
s> makefile('rb', None)
s> HTTP/1.1 200 OK\r\n
s> Server: testing stub value\r\n
s> Date: $HTTP_DATE$\r\n
s> Content-Type: text/plain\r\n
s> Content-Length: 96\r\n
s> \r\n
s> APIs can be accessed at /api/<name>, where <name> can be one of the following:\n
s> \n
s> exp-http-v2-0001