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import io
import re
import textwrap
from typing import Iterable, Optional
from mitmproxy.contentviews import base
from mitmproxy.utils import sliding_window
"""
A custom XML/HTML prettifier. Compared to other prettifiers, its main features are:
- Implemented in pure Python.
- Modifies whitespace only.
- Works with any input.
- Lazy evaluation.
The implementation is split into two main parts: tokenization and formatting of tokens.
"""
# http://www.xml.com/pub/a/2001/07/25/namingparts.html - this is close enough for what we do.
REGEX_TAG = re.compile(r"[a-zA-Z0-9._:\-]+(?!=)")
# https://www.w3.org/TR/html5/syntax.html#void-elements
HTML_VOID_ELEMENTS = {
"area", "base", "br", "col", "embed", "hr", "img", "input", "keygen", "link", "meta", "param",
"source", "track", "wbr"
}
NO_INDENT_TAGS = {"xml", "doctype", "html"}
INDENT = 2
class Token:
def __init__(self, data):
self.data = data
def __repr__(self):
return "{}({})".format(
type(self).__name__,
self.data
)
class Text(Token):
@property
def text(self):
return self.data.strip()
class Tag(Token):
@property
def tag(self):
t = REGEX_TAG.search(self.data)
if t is not None:
return t.group(0).lower()
return "<empty>"
@property
def is_comment(self) -> bool:
return self.data.startswith("<!--")
@property
def is_cdata(self) -> bool:
return self.data.startswith("<![CDATA[")
@property
def is_closing(self):
return self.data.startswith("</")
@property
def is_self_closing(self):
return self.is_comment or self.is_cdata or self.data.endswith(
"/>") or self.tag in HTML_VOID_ELEMENTS
@property
def is_opening(self):
return not self.is_closing and not self.is_self_closing
@property
def done(self):
if self.is_comment:
return self.data.endswith("-->")
elif self.is_cdata:
return self.data.endswith("]]>")
else:
# This fails for attributes that contain an unescaped ">"
return self.data.endswith(">")
def tokenize(data: str) -> Iterable[Token]:
token: Token = Text("")
i = 0
def readuntil(char, start, include=1):
nonlocal i
end = data.find(char, start)
if end == -1:
end = len(data)
ret = data[i:end + include]
i = end + include
return ret
while i < len(data):
if isinstance(token, Text):
token.data = readuntil("<", i, 0)
if token.text:
yield token
token = Tag("")
elif isinstance(token, Tag):
token.data += readuntil(">", i, 1)
if token.done:
yield token
token = Text("")
if token.data.strip():
yield token
def indent_text(data: str, prefix: str) -> str:
# Add spacing to first line so that we dedent in cases like this:
# <li>This is
# example text
# over multiple lines
# </li>
dedented = textwrap.dedent(" " * 32 + data).strip()
return textwrap.indent(dedented, prefix[:32])
def is_inline_text(a: Optional[Token], b: Optional[Token], c: Optional[Token]) -> bool:
if isinstance(a, Tag) and isinstance(b, Text) and isinstance(c, Tag):
if a.is_opening and "\n" not in b.data and c.is_closing and a.tag == c.tag:
return True
return False
def is_inline(prev2: Optional[Token], prev1: Optional[Token], t: Optional[Token], next1: Optional[Token], next2: Optional[Token]) -> bool:
if isinstance(t, Text):
return is_inline_text(prev1, t, next1)
elif isinstance(t, Tag):
if is_inline_text(prev2, prev1, t) or is_inline_text(t, next1, next2):
return True
if isinstance(next1, Tag) and t.is_opening and next1.is_closing and t.tag == next1.tag:
return True # <div></div> (start tag)
if isinstance(prev1, Tag) and prev1.is_opening and t.is_closing and prev1.tag == t.tag:
return True # <div></div> (end tag)
return False
class ElementStack:
"""
Keep track of how deeply nested our document is.
"""
def __init__(self):
self.open_tags = []
self.indent = ""
def push_tag(self, tag: str):
if len(self.open_tags) > 16:
return
self.open_tags.append(tag)
if tag not in NO_INDENT_TAGS:
self.indent += " " * INDENT
def pop_tag(self, tag: str):
if tag in self.open_tags:
remove_indent = 0
while True:
t = self.open_tags.pop()
if t not in NO_INDENT_TAGS:
remove_indent += INDENT
if t == tag:
break
self.indent = self.indent[:-remove_indent]
else:
pass # this closing tag has no start tag. let's keep indentation as-is.
def format_xml(tokens: Iterable[Token]) -> str:
out = io.StringIO()
context = ElementStack()
for prev2, prev1, token, next1, next2 in sliding_window.window(tokens, 2, 2):
if isinstance(token, Tag):
if token.is_opening:
out.write(indent_text(token.data, context.indent))
if not is_inline(prev2, prev1, token, next1, next2):
out.write("\n")
context.push_tag(token.tag)
elif token.is_closing:
context.pop_tag(token.tag)
if is_inline(prev2, prev1, token, next1, next2):
out.write(token.data)
else:
out.write(indent_text(token.data, context.indent))
out.write("\n")
else: # self-closing
out.write(indent_text(token.data, context.indent))
out.write("\n")
elif isinstance(token, Text):
if is_inline(prev2, prev1, token, next1, next2):
out.write(token.text)
else:
out.write(indent_text(token.data, context.indent))
out.write("\n")
else: # pragma: no cover
raise RuntimeError()
return out.getvalue()
class ViewXmlHtml(base.View):
name = "XML/HTML"
content_types = ["text/xml", "text/html"]
def __call__(self, data, **metadata):
# TODO:
# We should really have the message text as str here,
# not the message content as bytes.
# https://github.com/mitmproxy/mitmproxy/issues/1662#issuecomment-266192578
data = data.decode("utf8", "xmlcharrefreplace")
tokens = tokenize(data)
# TODO:
# Performance: Don't render the whole document right away.
# Let's wait with this until we have a sequence-like interface,
# this thing is reasonably fast right now anyway.
pretty = base.format_text(format_xml(tokens))
if "html" in data.lower():
t = "HTML"
else:
t = "XML"
return t, pretty
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