python: Rewrote SSI handler as a reusable module, and in Python3.

[ashd.git] / python3 / ashd / ssi.py

diff --git a/python3/ashd/ssi.py b/python3/ashd/ssi.py
new file mode 100644 (file)
index 0000000..ff59e6e
--- /dev/null
+++ b/python3/ashd/ssi.py
@@ -0,0 +1,146 @@
+"""Module for handling server-side-include formatted files
+
+This module is quite incomplete. I might complete it with more
+features as I need them. It will probably never be entirely compliant
+with Apache's version due to architectural differences.
+"""
+
+import sys, os, io, time, logging, functools
+from . import wsgiutil
+
+log = logging.getLogger("ssi")
+
+def parsecmd(text, p):
+    try:
+        while text[p].isspace(): p += 1
+        cmd = ""
+        while not text[p].isspace():
+            cmd += text[p]
+            p += 1
+        pars = {}
+        while True:
+            while text[p].isspace(): p += 1
+            if text[p:p + 3] == "-->":
+                return cmd, pars, p + 3
+            key = ""
+            while text[p].isalnum():
+                key += text[p]
+                p += 1
+            if key == "":
+                return None, {}, p
+            while text[p].isspace(): p += 1
+            if text[p] != '=':
+                continue
+            p += 1
+            while text[p].isspace(): p += 1
+            q = text[p]
+            if q != '"' and q != "'" and q != '`':
+                continue
+            val = ""
+            p += 1
+            while text[p] != q:
+                val += text[p]
+                p += 1
+            p += 1
+            pars[key] = val
+    except IndexError:
+        return None, {}, len(text)
+
+class context(object):
+    def __init__(self, out, root):
+        self.out = out
+        self.vars = {}
+        now = time.time()
+        self.vars["DOCUMENT_NAME"] = os.path.basename(root.path)
+        self.vars["DATE_GMT"] = time.asctime(time.gmtime(now))
+        self.vars["DATE_LOCAL"] = time.asctime(time.localtime(now))
+        self.vars["LAST_MODIFIED"] = time.asctime(time.localtime(root.mtime))
+
+class ssifile(object):
+    def __init__(self, path):
+        self.path = path
+        self.mtime = os.stat(self.path).st_mtime
+        with open(path) as fp:
+            self.parts = self.parse(fp.read())
+
+    def text(self, text, ctx):
+        ctx.out.write(text)
+
+    def echo(self, var, enc, ctx):
+        if var in ctx.vars:
+            ctx.out.write(enc(ctx.vars[var]))
+
+    def include(self, path, ctx):
+        try:
+            nest = getfile(os.path.join(os.path.dirname(self.path), path))
+        except Exception:
+            log.warning("%s: could not find included file %s" % (self.path, path))
+            return
+        nest.process(ctx)
+
+    def process(self, ctx):
+        for part in self.parts:
+            part(ctx)
+
+    def resolvecmd(self, cmd, pars):
+        if cmd == "include":
+            if "file" in pars:
+                return functools.partial(self.include, pars["file"])
+            elif "virtual" in pars:
+                # XXX: For now, just include the file as-is. Change
+                # when necessary.
+                return functools.partial(self.include, pars["virtual"])
+            else:
+                log.warning("%s: invalid `include' directive" % self.path)
+                return None
+        elif cmd == "echo":
+            if not "var" in pars:
+                log.warning("%s: invalid `echo' directive" % self.path)
+                return None
+            enc = wsgiutil.htmlquote
+            if "encoding" in pars:
+                if pars["encoding"] == "entity":
+                    enc = wsgiutil.htmlquote
+            return functools.partial(self.echo, pars["var"], enc)
+        else:
+            log.warning("%s: unknown SSI command `%s'" % (self.path, cmd))
+            return None
+
+    def parse(self, text):
+        ret = []
+        p = 0
+        while True:
+            p2 = text.find("<!--#", p)
+            if p2 < 0:
+                ret.append(functools.partial(self.text, text[p:]))
+                return ret
+            ret.append(functools.partial(self.text, text[p:p2]))
+            cmd, pars, p = parsecmd(text, p2 + 5)
+            if cmd is not None:
+                cmd = self.resolvecmd(cmd, pars)
+                if cmd is not None:
+                    ret.append(cmd)
+
+filecache = {}
+
+def getfile(path):
+    path = os.path.normpath(path)
+    cf = filecache.get(path)
+    if not cf:
+        cf = filecache[path] = ssifile(path)
+    elif os.stat(path).st_mtime != cf.mtime:
+        cf = filecache[path] = ssifile(path)
+    return cf
+
+def wsgi(env, startreq):
+    try:
+        if env["PATH_INFO"] != "":
+            return wsgiutil.simpleerror(env, startreq, 404, "Not Found", "The resource specified by the URL does not exist.")
+        root = getfile(env["SCRIPT_FILENAME"])
+        buf = io.StringIO()
+        root.process(context(buf, root))
+    except Exception:
+        return wsgituil.simpleerror(env, startreq, 500, "Internal Error", "The server encountered an unpexpected error while handling SSI.")
+    ret = buf.getvalue().encode("utf8")
+    startreq("200 OK", [("Content-Type", "text/html; charset=UTF-8"), ("Content-Length", str(len(ret)))])
+    return [ret]