python3/ashd/ssi.py

   1 """Module for handling server-side-include formatted files
   2
   3 This module is quite incomplete. I might complete it with more
   4 features as I need them. It will probably never be entirely compliant
   5 with Apache's version due to architectural differences.
   6 """
   7
   8 import sys, os, io, time, logging, functools
   9 from . import wsgiutil
  10
  11 log = logging.getLogger("ssi")
  12
  13 def parsecmd(text, p):
  14     try:
  15         while text[p].isspace(): p += 1
  16         cmd = ""
  17         while not text[p].isspace():
  18             cmd += text[p]
  19             p += 1
  20         pars = {}
  21         while True:
  22             while text[p].isspace(): p += 1
  23             if text[p:p + 3] == "-->":
  24                 return cmd, pars, p + 3
  25             key = ""
  26             while text[p].isalnum():
  27                 key += text[p]
  28                 p += 1
  29             if key == "":
  30                 return None, {}, p
  31             while text[p].isspace(): p += 1
  32             if text[p] != '=':
  33                 continue
  34             p += 1
  35             while text[p].isspace(): p += 1
  36             q = text[p]
  37             if q != '"' and q != "'" and q != '`':
  38                 continue
  39             val = ""
  40             p += 1
  41             while text[p] != q:
  42                 val += text[p]
  43                 p += 1
  44             p += 1
  45             pars[key] = val
  46     except IndexError:
  47         return None, {}, len(text)
  48
  49 class context(object):
  50     def __init__(self, out, root):
  51         self.out = out
  52         self.vars = {}
  53         now = time.time()
  54         self.vars["DOCUMENT_NAME"] = os.path.basename(root.path)
  55         self.vars["DATE_GMT"] = time.asctime(time.gmtime(now))
  56         self.vars["DATE_LOCAL"] = time.asctime(time.localtime(now))
  57         self.vars["LAST_MODIFIED"] = time.asctime(time.localtime(root.mtime))
  58
  59 class ssifile(object):
  60     def __init__(self, path):
  61         self.path = path
  62         self.mtime = os.stat(self.path).st_mtime
  63         with open(path) as fp:
  64             self.parts = self.parse(fp.read())
  65
  66     def text(self, text, ctx):
  67         ctx.out.write(text)
  68
  69     def echo(self, var, enc, ctx):
  70         if var in ctx.vars:
  71             ctx.out.write(enc(ctx.vars[var]))
  72
  73     def include(self, path, ctx):
  74         try:
  75             nest = getfile(os.path.join(os.path.dirname(self.path), path))
  76         except Exception:
  77             log.warning("%s: could not find included file %s" % (self.path, path))
  78             return
  79         nest.process(ctx)
  80
  81     def process(self, ctx):
  82         for part in self.parts:
  83             part(ctx)
  84
  85     def resolvecmd(self, cmd, pars):
  86         if cmd == "include":
  87             if "file" in pars:
  88                 return functools.partial(self.include, pars["file"])
  89             elif "virtual" in pars:
  90                 # XXX: For now, just include the file as-is. Change
  91                 # when necessary.
  92                 return functools.partial(self.include, pars["virtual"])
  93             else:
  94                 log.warning("%s: invalid `include' directive" % self.path)
  95                 return None
  96         elif cmd == "echo":
  97             if not "var" in pars:
  98                 log.warning("%s: invalid `echo' directive" % self.path)
  99                 return None
 100             enc = wsgiutil.htmlquote
 101             if "encoding" in pars:
 102                 if pars["encoding"] == "entity":
 103                     enc = wsgiutil.htmlquote
 104             return functools.partial(self.echo, pars["var"], enc)
 105         else:
 106             log.warning("%s: unknown SSI command `%s'" % (self.path, cmd))
 107             return None
 108
 109     def parse(self, text):
 110         ret = []
 111         p = 0
 112         while True:
 113             p2 = text.find("<!--#", p)
 114             if p2 < 0:
 115                 ret.append(functools.partial(self.text, text[p:]))
 116                 return ret
 117             ret.append(functools.partial(self.text, text[p:p2]))
 118             cmd, pars, p = parsecmd(text, p2 + 5)
 119             if cmd is not None:
 120                 cmd = self.resolvecmd(cmd, pars)
 121                 if cmd is not None:
 122                     ret.append(cmd)
 123
 124 filecache = {}
 125
 126 def getfile(path):
 127     path = os.path.normpath(path)
 128     cf = filecache.get(path)
 129     if not cf:
 130         cf = filecache[path] = ssifile(path)
 131     elif os.stat(path).st_mtime != cf.mtime:
 132         cf = filecache[path] = ssifile(path)
 133     return cf
 134
 135 def wsgi(env, startreq):
 136     try:
 137         if env["PATH_INFO"] != "":
 138             return wsgiutil.simpleerror(env, startreq, 404, "Not Found", "The resource specified by the URL does not exist.")
 139         root = getfile(env["SCRIPT_FILENAME"])
 140         buf = io.StringIO()
 141         root.process(context(buf, root))
 142     except Exception:
 143         return wsgituil.simpleerror(env, startreq, 500, "Internal Error", "The server encountered an unpexpected error while handling SSI.")
 144     ret = buf.getvalue().encode("utf8")
 145     startreq("200 OK", [("Content-Type", "text/html; charset=UTF-8"), ("Content-Length", str(len(ret)))])
 146     return [ret]