X-Git-Url: http://xvm.mit.edu/gitweb/invirt/packages/invirt-web.git/blobdiff_plain/892175e9d1c88d7db0c6bcc28e3ee4598ea035a4..55a1b4d83e6a40a12ec3b540692e98c50cef244e:/code/main.py?ds=inline

diff --git a/code/main.py b/code/main.py
index 385a2a6..e4727a8 100755
--- a/code/main.py
+++ b/code/main.py
@@ -6,7 +6,7 @@ import cPickle
 import cgi
 import datetime
 import hmac
-import os
+import random
 import sha
 import simplejson
 import sys
@@ -18,7 +18,7 @@ def revertStandardError():
     """Move stderr to stdout, and return the contents of the old stderr."""
     errio = sys.stderr
     if not isinstance(errio, StringIO):
-        return None
+        return ''
     sys.stderr = sys.stdout
     errio.seek(0)
     return errio.read()
@@ -31,18 +31,25 @@ def printError():
 if __name__ == '__main__':
     import atexit
     atexit.register(printError)
-    sys.stderr = StringIO()
-
-sys.path.append('/home/ecprice/.local/lib/python2.5/site-packages')
 
 import templates
 from Cheetah.Template import Template
-import sipb_xen_database
-from sipb_xen_database import Machine, CDROM, ctx, connect, MachineAccess, Type, Autoinstall
 import validation
 import cache_acls
-from webcommon import InvalidInput, CodeError, g
+from webcommon import InvalidInput, CodeError, State
 import controls
+from getafsgroups import getAfsGroupMembers
+from invirt import database
+from invirt.database import Machine, CDROM, session, connect, MachineAccess, Type, Autoinstall
+from invirt.config import structs as config
+
+def pathSplit(path):
+    if path.startswith('/'):
+        path = path[1:]
+    i = path.find('/')
+    if i == -1:
+        i = len(path)
+    return path[:i], path[i:]
 
 class Checkpoint:
     def __init__(self):
@@ -77,7 +84,8 @@ def makeErrorPre(old, addition):
     else:
         return '<p>STDERR:</p><pre>' + str(addition) + '</pre>'
 
-Template.sipb_xen_database = sipb_xen_database
+Template.database = database
+Template.config = config
 Template.helppopup = staticmethod(helppopup)
 Template.err = None
 
@@ -105,6 +113,7 @@ class Defaults:
     cdrom = ''
     autoinstall = ''
     name = ''
+    description = ''
     type = 'linux-hvm'
 
     def __init__(self, max_memory=None, max_disk=None, **kws):
@@ -119,15 +128,9 @@ class Defaults:
 
 DEFAULT_HEADERS = {'Content-Type': 'text/html'}
 
-def error(op, user, fields, err, emsg):
-    """Print an error page when a CodeError occurs"""
-    d = dict(op=op, user=user, errorMessage=str(err),
-             stderr=emsg)
-    return templates.error(searchList=[d])
-
-def invalidInput(op, user, fields, err, emsg):
+def invalidInput(op, username, fields, err, emsg):
     """Print an error page when an InvalidInput exception occurs"""
-    d = dict(op=op, user=user, err_field=err.err_field,
+    d = dict(op=op, user=username, err_field=err.err_field,
              err_value=str(err.err_value), stderr=emsg,
              errorMessage=str(err))
     return templates.invalid(searchList=[d])
@@ -142,49 +145,25 @@ def hasVnc(status):
             return 'location' in d
     return False
 
-def parseCreate(user, fields):
-    name = fields.getfirst('name')
-    if not validation.validMachineName(name):
-        raise InvalidInput('name', name, 'You must provide a machine name.  Max 22 chars, alnum plus \'-\' and \'_\'.')
-    name = name.lower()
-
-    if Machine.get_by(name=name):
-        raise InvalidInput('name', name,
-                           "Name already exists.")
-
-    owner = validation.testOwner(user, fields.getfirst('owner'))
-
-    memory = fields.getfirst('memory')
-    memory = validation.validMemory(owner, memory, on=True)
-
-    disk_size = fields.getfirst('disk')
-    disk_size = validation.validDisk(owner, disk_size)
+def parseCreate(username, state, fields):
+    kws = dict([(kw, fields.getfirst(kw)) for kw in 'name description owner memory disksize vmtype cdrom autoinstall'.split()])
+    validate = validation.Validate(username, state, strict=True, **kws)
+    return dict(contact=username, name=validate.name, description=validate.description, memory=validate.memory,
+                disksize=validate.disksize, owner=validate.owner, machine_type=validate.vmtype,
+                cdrom=getattr(validate, 'cdrom', None),
+                autoinstall=getattr(validate, 'autoinstall', None))
 
-    vm_type = fields.getfirst('vmtype')
-    vm_type = validation.validVmType(vm_type)
-
-    cdrom = fields.getfirst('cdrom')
-    if cdrom is not None and not CDROM.get(cdrom):
-        raise CodeError("Invalid cdrom type '%s'" % cdrom)
-
-    clone_from = fields.getfirst('clone_from')
-    if clone_from and clone_from != 'ice3':
-        raise CodeError("Invalid clone image '%s'" % clone_from)
-
-    return dict(contact=user, name=name, memory=memory, disk_size=disk_size,
-                owner=owner, machine_type=vm_type, cdrom=cdrom, clone_from=clone_from)
-
-def create(user, fields):
+def create(username, state, path, fields):
     """Handler for create requests."""
     try:
-        parsed_fields = parseCreate(user, fields)
-        machine = controls.createVm(**parsed_fields)
+        parsed_fields = parseCreate(username, state, fields)
+        machine = controls.createVm(username, state, **parsed_fields)
     except InvalidInput, err:
         pass
     else:
         err = None
-    g.clear() #Changed global state
-    d = getListDict(user)
+    state.clear() #Changed global state
+    d = getListDict(username, state)
     d['err'] = err
     if err:
         for field in fields.keys():
@@ -194,16 +173,16 @@ def create(user, fields):
     return templates.list(searchList=[d])
 
 
-def getListDict(user):
+def getListDict(username, state):
     """Gets the list of local variables used by list.tmpl."""
     checkpoint.checkpoint('Starting')
-    machines = g.machines
+    machines = state.machines
     checkpoint.checkpoint('Got my machines')
     on = {}
     has_vnc = {}
-    xmlist = g.xmlist
+    xmlist = state.xmlist
     checkpoint.checkpoint('Got uptimes')
-    can_clone = 'ice3' not in g.xmlist_raw
+    can_clone = 'ice3' not in state.xmlist_raw
     for m in machines:
         if m not in xmlist:
             has_vnc[m] = 'Off'
@@ -216,19 +195,19 @@ def getListDict(user):
                 has_vnc[m] = "WTF?"
             else:
                 has_vnc[m] = "ParaVM"+helppopup("ParaVM Console")
-    max_memory = validation.maxMemory(user)
-    max_disk = validation.maxDisk(user)
+    max_memory = validation.maxMemory(username, state)
+    max_disk = validation.maxDisk(username)
     checkpoint.checkpoint('Got max mem/disk')
     defaults = Defaults(max_memory=max_memory,
                         max_disk=max_disk,
-                        owner=user,
+                        owner=username,
                         cdrom='gutsy-i386')
     checkpoint.checkpoint('Got defaults')
     def sortkey(machine):
-        return (machine.owner != user, machine.owner, machine.name)
+        return (machine.owner != username, machine.owner, machine.name)
     machines = sorted(machines, key=sortkey)
-    d = dict(user=user,
-             cant_add_vm=validation.cantAddVm(user),
+    d = dict(user=username,
+             cant_add_vm=validation.cantAddVm(username, state),
              max_memory=max_memory,
              max_disk=max_disk,
              defaults=defaults,
@@ -237,14 +216,14 @@ def getListDict(user):
              can_clone=can_clone)
     return d
 
-def listVms(user, fields):
+def listVms(username, state, path, fields):
     """Handler for list requests."""
     checkpoint.checkpoint('Getting list dict')
-    d = getListDict(user)
+    d = getListDict(username, state)
     checkpoint.checkpoint('Got list dict')
     return templates.list(searchList=[d])
 
-def vnc(user, fields):
+def vnc(username, state, path, fields):
     """VNC applet page.
 
     Note that due to same-domain restrictions, the applet connects to
@@ -264,12 +243,12 @@ def vnc(user, fields):
     Remember to enable iptables!
     echo 1 > /proc/sys/net/ipv4/ip_forward
     """
-    machine = validation.testMachineId(user, fields.getfirst('machine_id'))
+    machine = validation.Validate(username, state, machine_id=fields.getfirst('machine_id')).machine
 
     TOKEN_KEY = "0M6W0U1IXexThi5idy8mnkqPKEq1LtEnlK/pZSn0cDrN"
 
     data = {}
-    data["user"] = user
+    data["user"] = username
     data["machine"] = machine.name
     data["expires"] = time.time()+(5*60)
     pickled_data = cPickle.dumps(data)
@@ -278,15 +257,21 @@ def vnc(user, fields):
     token = {'data': pickled_data, 'digest': m.digest()}
     token = cPickle.dumps(token)
     token = base64.urlsafe_b64encode(token)
+    host = controls.listHost(machine)
+    if host:
+        port = 10003 + [h.hostname for h in config.hosts].index(host)
+    else:
+        port = 5900 # dummy
 
     status = controls.statusInfo(machine)
     has_vnc = hasVnc(status)
 
-    d = dict(user=user,
+    d = dict(user=username,
              on=status,
              has_vnc=has_vnc,
              machine=machine,
-             hostname=os.environ.get('SERVER_NAME', 'localhost'),
+             hostname=state.environ.get('SERVER_NAME', 'localhost'),
+             port=port,
              authtoken=token)
     return templates.vnc(searchList=[d])
 
@@ -298,7 +283,7 @@ def getHostname(nic):
     if nic.hostname and '.' in nic.hostname:
         return nic.hostname
     elif nic.machine:
-        return nic.machine.name + '.xvm.mit.edu'
+        return nic.machine.name + '.' + config.dns.domains[0]
     else:
         return None
 
@@ -341,110 +326,104 @@ def getDiskInfo(data_dict, machine):
         data_dict['%s_size' % name] = "%0.1f GiB" % (disk.size / 1024.)
     return disk_fields
 
-def command(user, fields):
+def command(username, state, path, fields):
     """Handler for running commands like boot and delete on a VM."""
     back = fields.getfirst('back')
     try:
-        d = controls.commandResult(user, fields)
+        d = controls.commandResult(username, state, fields)
         if d['command'] == 'Delete VM':
             back = 'list'
     except InvalidInput, err:
         if not back:
             raise
-        #print >> sys.stderr, err
+        print >> sys.stderr, err
         result = err
     else:
         result = 'Success!'
         if not back:
             return templates.command(searchList=[d])
     if back == 'list':
-        g.clear() #Changed global state
-        d = getListDict(user)
+        state.clear() #Changed global state
+        d = getListDict(username, state)
         d['result'] = result
         return templates.list(searchList=[d])
     elif back == 'info':
-        machine = validation.testMachineId(user, fields.getfirst('machine_id'))
-        return ({'Status': '302',
-                 'Location': '/info?machine_id=%d' % machine.machine_id},
+        machine = validation.Validate(username, state, machine_id=fields.getfirst('machine_id')).machine
+        return ({'Status': '303 See Other',
+                 'Location': 'info?machine_id=%d' % machine.machine_id},
                 "You shouldn't see this message.")
     else:
         raise InvalidInput('back', back, 'Not a known back page.')
 
-def modifyDict(user, fields):
+def modifyDict(username, state, fields):
     """Modify a machine as specified by CGI arguments.
 
     Return a list of local variables for modify.tmpl.
     """
     olddisk = {}
-    transaction = ctx.current.create_transaction()
+    session.begin()
     try:
-        machine = validation.testMachineId(user, fields.getfirst('machine_id'))
-        owner = validation.testOwner(user, fields.getfirst('owner'), machine)
-        admin = validation.testAdmin(user, fields.getfirst('administrator'),
-                                     machine)
-        contact = validation.testContact(user, fields.getfirst('contact'),
-                                         machine)
-        name = validation.testName(user, fields.getfirst('name'), machine)
+        kws = dict([(kw, fields.getfirst(kw)) for kw in 'machine_id owner admin contact name description memory vmtype disksize'.split()])
+        validate = validation.Validate(username, state, **kws)
+        machine = validate.machine
         oldname = machine.name
-        command = "modify"
 
-        memory = fields.getfirst('memory')
-        if memory is not None:
-            memory = validation.validMemory(owner, memory, machine, on=False)
-            machine.memory = memory
+        if hasattr(validate, 'memory'):
+            machine.memory = validate.memory
 
-        vm_type = validation.validVmType(fields.getfirst('vmtype'))
-        if vm_type is not None:
-            machine.type = vm_type
+        if hasattr(validate, 'vmtype'):
+            machine.type = validate.vmtype
 
-        disksize = validation.testDisk(owner, fields.getfirst('disk'))
-        if disksize is not None:
-            disksize = validation.validDisk(owner, disksize, machine)
+        if hasattr(validate, 'disksize'):
+            disksize = validate.disksize
             disk = machine.disks[0]
             if disk.size != disksize:
                 olddisk[disk.guest_device_name] = disksize
                 disk.size = disksize
-                ctx.current.save(disk)
+                session.save_or_update(disk)
 
         update_acl = False
-        if owner is not None and owner != machine.owner:
-            machine.owner = owner
+        if hasattr(validate, 'owner') and validate.owner != machine.owner:
+            machine.owner = validate.owner
             update_acl = True
-        if name is not None:
-            machine.name = name
-        if admin is not None and admin != machine.administrator:
-            machine.administrator = admin
+        if hasattr(validate, 'name'):
+            machine.name = validate.name
+        if hasattr(validate, 'description'):
+            machine.description = validate.description
+        if hasattr(validate, 'admin') and validate.admin != machine.administrator:
+            machine.administrator = validate.admin
             update_acl = True
-        if contact is not None:
-            machine.contact = contact
+        if hasattr(validate, 'contact'):
+            machine.contact = validate.contact
 
-        ctx.current.save(machine)
+        session.save_or_update(machine)
         if update_acl:
+            print >> sys.stderr, machine, machine.administrator
             cache_acls.refreshMachine(machine)
-        transaction.commit()
+        session.commit()
     except:
-        transaction.rollback()
+        session.rollback()
         raise
     for diskname in olddisk:
         controls.resizeDisk(oldname, diskname, str(olddisk[diskname]))
-    if name is not None:
-        controls.renameMachine(machine, oldname, name)
-    return dict(user=user,
-                command=command,
+    if hasattr(validate, 'name'):
+        controls.renameMachine(machine, oldname, validate.name)
+    return dict(user=username,
+                command="modify",
                 machine=machine)
 
-def modify(user, fields):
+def modify(username, state, path, fields):
     """Handler for modifying attributes of a machine."""
     try:
-        modify_dict = modifyDict(user, fields)
+        modify_dict = modifyDict(username, state, fields)
     except InvalidInput, err:
         result = None
-        machine = validation.testMachineId(user, fields.getfirst('machine_id'))
+        machine = validation.Validate(username, state, machine_id=fields.getfirst('machine_id')).machine
     else:
         machine = modify_dict['machine']
         result = 'Success!'
         err = None
-    info_dict = infoDict(user, machine)
+    info_dict = infoDict(username, state, machine)
     info_dict['err'] = err
     if err:
         for field in fields.keys():
@@ -453,7 +432,7 @@ def modify(user, fields):
     return templates.info(searchList=[info_dict])
 
 
-def helpHandler(user, fields):
+def helpHandler(username, state, path, fields):
     """Handler for help messages."""
     simple = fields.getfirst('simple')
     subjects = fields.getlist('subject')
@@ -461,8 +440,8 @@ def helpHandler(user, fields):
     help_mapping = {'ParaVM Console': """
 ParaVM machines do not support local console access over VNC.  To
 access the serial console of these machines, you can SSH with Kerberos
-to console.xvm.mit.edu, using the name of the machine as your
-username.""",
+to console.%s, using the name of the machine as your
+username.""" % config.dns.domains[0],
                     'HVM/ParaVM': """
 HVM machines use the virtualization features of the processor, while
 ParaVM machines use Xen's emulation of virtualization features.  You
@@ -490,13 +469,17 @@ active machines.""",
 setting <tt>fb=false</tt> to disable the framebuffer.  If you don't,
 your machine will run just fine, but the applet's display of the
 console will suffer artifacts.
+""",
+                    'Windows': """
+<strong>Windows Vista:</strong> The Vista image is licensed for all MIT students and will automatically activate off the network; see <a href="/static/msca-email.txt">the licensing confirmation e-mail</a> for details. The installer req	uires 512 MB RAM and at least 7.5 GB disk space (15 GB or more recommended).<br>
+<strong>Windows XP:</strong> This is the volume license CD image. You will need your own volume license key to complete the install. We do not have these available for the general MIT community; ask your department if they have one.
 """
                     }
 
     if not subjects:
         subjects = sorted(help_mapping.keys())
 
-    d = dict(user=user,
+    d = dict(user=username,
              simple=simple,
              subjects=subjects,
              mapping=help_mapping)
@@ -504,11 +487,11 @@ console will suffer artifacts.
     return templates.help(searchList=[d])
 
 
-def badOperation(u, e):
+def badOperation(u, s, p, e):
     """Function called when accessing an unknown URI."""
-    raise CodeError("Unknown operation")
+    return ({'Status': '404 Not Found'}, 'Invalid operation.')
 
-def infoDict(user, machine):
+def infoDict(username, state, machine):
     """Get the variables used by info.tmpl."""
     status = controls.statusInfo(machine)
     checkpoint.checkpoint('Getting status info')
@@ -520,6 +503,7 @@ def infoDict(user, machine):
         cputime = None
     else:
         main_status = dict(status[1:])
+        main_status['host'] = controls.listHost(machine)
         start_time = float(main_status.get('start_time', 0))
         uptime = datetime.timedelta(seconds=int(time.time()-start_time))
         cpu_time_float = float(main_status.get('cpu_time', 0))
@@ -528,6 +512,7 @@ def infoDict(user, machine):
     display_fields = """name uptime memory state cpu_weight on_reboot 
      on_poweroff on_crash on_xend_start on_xend_stop bootloader""".split()
     display_fields = [('name', 'Name'),
+                      ('description', 'Description'),
                       ('owner', 'Owner'),
                       ('administrator', 'Administrator'),
                       ('contact', 'Contact'),
@@ -535,6 +520,7 @@ def infoDict(user, machine):
                       'NIC_INFO',
                       ('uptime', 'uptime'),
                       ('cputime', 'CPU usage'),
+                      ('host', 'Hosted on'),
                       ('memory', 'RAM'),
                       'DISK_INFO',
                       ('state', 'state (xen format)'),
@@ -549,6 +535,7 @@ def infoDict(user, machine):
     fields = []
     machine_info = {}
     machine_info['name'] = machine.name
+    machine_info['description'] = machine.description
     machine_info['type'] = machine.type.hvm and 'HVM' or 'ParaVM'
     machine_info['owner'] = machine.owner
     machine_info['administrator'] = machine.administrator
@@ -579,16 +566,16 @@ def infoDict(user, machine):
     checkpoint.checkpoint('Got fields')
 
 
-    max_mem = validation.maxMemory(machine.owner, machine, False)
+    max_mem = validation.maxMemory(machine.owner, state, machine, False)
     checkpoint.checkpoint('Got mem')
     max_disk = validation.maxDisk(machine.owner, machine)
     defaults = Defaults()
-    for name in 'machine_id name administrator owner memory contact'.split():
+    for name in 'machine_id name description administrator owner memory contact'.split():
         setattr(defaults, name, getattr(machine, name))
     defaults.type = machine.type.type_id
     defaults.disk = "%0.2f" % (machine.disks[0].size/1024.)
     checkpoint.checkpoint('Got defaults')
-    d = dict(user=user,
+    d = dict(user=username,
              on=status is not None,
              machine=machine,
              defaults=defaults,
@@ -601,17 +588,33 @@ def infoDict(user, machine):
              fields = fields)
     return d
 
-def info(user, fields):
+def info(username, state, path, fields):
     """Handler for info on a single VM."""
-    machine = validation.testMachineId(user, fields.getfirst('machine_id'))
-    d = infoDict(user, machine)
+    machine = validation.Validate(username, state, machine_id=fields.getfirst('machine_id')).machine
+    d = infoDict(username, state, machine)
     checkpoint.checkpoint('Got infodict')
     return templates.info(searchList=[d])
 
-def unauthFront(_, fields):
+def unauthFront(_, _2, _3, fields):
     """Information for unauth'd users."""
     return templates.unauth(searchList=[{'simple' : True}])
 
+def admin(username, state, path, fields):
+    if path == '':
+        return ({'Status': '303 See Other',
+                 'Location': 'admin/'},
+                "You shouldn't see this message.")
+    if not username in getAfsGroupMembers(config.web.adminacl, 'athena.mit.edu'):
+        raise InvalidInput('username', username,
+                           'Not in admin group %s.' % config.web.adminacl)
+    newstate = State(username, isadmin=True)
+    newstate.environ = state.environ
+    return handler(username, newstate, path, fields)
+
+def throwError(_, __, ___, ____):
+    """Throw an error, to test the error-tracing mechanisms."""
+    raise RuntimeError("test of the emergency broadcast system")
+
 mapping = dict(list=listVms,
                vnc=vnc,
                command=command,
@@ -619,7 +622,10 @@ mapping = dict(list=listVms,
                info=info,
                create=create,
                help=helpHandler,
-               unauth=unauthFront)
+               unauth=unauthFront,
+               admin=admin,
+               overlord=admin,
+               errortest=throwError)
 
 def printHeaders(headers):
     """Print a dictionary as HTTP headers."""
@@ -627,86 +633,117 @@ def printHeaders(headers):
         print '%s: %s' % (key, value)
     print
 
+def send_error_mail(subject, body):
+    import subprocess
+
+    to = config.web.errormail
+    mail = """To: %s
+From: root@%s
+Subject: %s
+
+%s
+""" % (to, config.web.hostname, subject, body)
+    p = subprocess.Popen(['/usr/sbin/sendmail', to], stdin=subprocess.PIPE)
+    p.stdin.write(mail)
+    p.stdin.close()
+    p.wait()
+
+def show_error(op, username, fields, err, emsg, traceback):
+    """Print an error page when an exception occurs"""
+    d = dict(op=op, user=username, fields=fields,
+             errorMessage=str(err), stderr=emsg, traceback=traceback)
+    details = templates.error_raw(searchList=[d])
+    exclude = config.web.errormail_exclude
+    if username not in exclude and '*' not in exclude:
+        send_error_mail('xvm error on %s for %s: %s' % (op, username, err),
+                        details)
+    d['details'] = details
+    return templates.error(searchList=[d])
 
-def getUser():
+def getUser(environ):
     """Return the current user based on the SSL environment variables"""
-    email = os.environ.get('SSL_CLIENT_S_DN_Email', None)
-    if email is None:
-        return None
-    return email.split("@")[0]
+    return environ.get('REMOTE_USER', None)
 
-def main(operation, user, fields):
-    start_time = time.time()
+def handler(username, state, path, fields):
+    operation, path = pathSplit(path)
+    if not operation:
+        operation = 'list'
+    print 'Starting', operation
     fun = mapping.get(operation, badOperation)
-
-    if fun not in (helpHandler, ):
-        connect('postgres://sipb-xen@sipb-xen-dev.mit.edu/sipb_xen')
-    try:
-        checkpoint.checkpoint('Before')
-        output = fun(u, fields)
-        checkpoint.checkpoint('After')
-
-        headers = dict(DEFAULT_HEADERS)
-        if isinstance(output, tuple):
-            new_headers, output = output
-            headers.update(new_headers)
-        e = revertStandardError()
-        if e:
-            output.addError(e)
-        printHeaders(headers)
-        output_string =  str(output)
-        checkpoint.checkpoint('output as a string')
-        print output_string
+    return fun(username, state, path, fields)
+
+class App:
+    def __init__(self, environ, start_response):
+        self.environ = environ
+        self.start = start_response
+
+        self.username = getUser(environ)
+        self.state = State(self.username)
+        self.state.environ = environ
+
+        random.seed() #sigh
+
+    def __iter__(self):
+        start_time = time.time()
+        database.clear_cache()
+        sys.stderr = StringIO()
+        fields = cgi.FieldStorage(fp=self.environ['wsgi.input'], environ=self.environ)
+        operation = self.environ.get('PATH_INFO', '')
+        if not operation:
+            self.start("301 Moved Permanently", [('Location', './')])
+            return
+        if self.username is None:
+            operation = 'unauth'
+
+        try:
+            checkpoint.checkpoint('Before')
+            output = handler(self.username, self.state, operation, fields)
+            checkpoint.checkpoint('After')
+
+            headers = dict(DEFAULT_HEADERS)
+            if isinstance(output, tuple):
+                new_headers, output = output
+                headers.update(new_headers)
+            e = revertStandardError()
+            if e:
+                if hasattr(output, 'addError'):
+                    output.addError(e)
+                else:
+                    # This only happens on redirects, so it'd be a pain to get
+                    # the message to the user.  Maybe in the response is useful.
+                    output = output + '\n\nstderr:\n' + e
+            output_string =  str(output)
+            checkpoint.checkpoint('output as a string')
+        except Exception, err:
+            if not fields.has_key('js'):
+                if isinstance(err, InvalidInput):
+                    self.start('200 OK', [('Content-Type', 'text/html')])
+                    e = revertStandardError()
+                    yield str(invalidInput(operation, self.username, fields,
+                                           err, e))
+                    return
+            import traceback
+            self.start('500 Internal Server Error',
+                       [('Content-Type', 'text/html')])
+            e = revertStandardError()
+            s = show_error(operation, self.username, fields,
+                           err, e, traceback.format_exc())
+            yield str(s)
+            return
+        status = headers.setdefault('Status', '200 OK')
+        del headers['Status']
+        self.start(status, headers.items())
+        yield output_string
         if fields.has_key('timedebug'):
-            print '<pre>%s</pre>' % checkpoint
-    except Exception, err:
-        if not fields.has_key('js'):
-            if isinstance(err, CodeError):
-                print 'Content-Type: text/html\n'
-                e = revertStandardError()
-                print error(operation, u, fields, err, e)
-                sys.exit(1)
-            if isinstance(err, InvalidInput):
-                print 'Content-Type: text/html\n'
-                e = revertStandardError()
-                print invalidInput(operation, u, fields, err, e)
-                sys.exit(1)
-        print 'Content-Type: text/plain\n'
-        print 'Uh-oh!  We experienced an error.'
-        print 'Please email xvm-dev@mit.edu with the contents of this page.'
-        print '----'
-        e = revertStandardError()
-        print e
-        print '----'
-        raise
-
-if __name__ == '__main__':
-    fields = cgi.FieldStorage()
-
-    if fields.has_key('sqldebug'):
-        import logging
-        logging.basicConfig()
-        logging.getLogger('sqlalchemy.engine').setLevel(logging.INFO)
-        logging.getLogger('sqlalchemy.orm.unitofwork').setLevel(logging.INFO)
-
-    u = getUser()
-    g.user = u
-    operation = os.environ.get('PATH_INFO', '')
-    if not operation:
-        print "Status: 301 Moved Permanently"
-        print 'Location: ' + os.environ['SCRIPT_NAME']+'/\n'
-        sys.exit(0)
+            yield '<pre>%s</pre>' % cgi.escape(str(checkpoint))
 
-    if u is None:
-        operation = 'unauth'
+def constructor():
+    connect()
+    return App
 
-    if operation.startswith('/'):
-        operation = operation[1:]
-    if not operation:
-        operation = 'list'
+def main():
+    from flup.server.fcgi_fork import WSGIServer
+    WSGIServer(constructor()).run()
 
-    if os.getenv("SIPB_XEN_PROFILE"):
-        import profile
-        profile.run('main(operation, u, fields)', 'log-'+operation)
-    else:
-        main(operation, u, fields)
+if __name__ == '__main__':
+    main()