#!/usr/bin/python
# -*- coding: utf-8 -*-     

import time
import datetime
import base64
import argparse
import errno
from certtools import *

NAGIOS_OK = 0
NAGIOS_WARN = 1
NAGIOS_CRIT = 2
NAGIOS_UNKNOWN = 3

DEFAULT_CUR_FILE = 'all-sth.json'

base_urls = [
    # "https://plausible.ct.nordu.net/",
    # "https://ct1.digicert-ct.com/log/", 
    "https://ct.izenpe.com/",
    # "https://log.certly.io/", 
    # "https://ct.googleapis.com/aviator/", 
    # "https://ct.googleapis.com/pilot/",
    # "https://ct.googleapis.com/rocketeer/",
    "https://ct.ws.symantec.com/",
    "https://ctlog.api.venafi.com/",
]

parser = argparse.ArgumentParser(description="")
parser.add_argument('--audit', action='store_true', help="run lightweight auditor verifying consistency in STH")
parser.add_argument('--monitor', action='store_true', help="run full monitoring for all logs")
parser.add_argument('--audit2', action='store_true', help="run medium-weight auditor verifying consistency in STH and inclusion proofs of new entries")
parser.add_argument('--audit3', action='store_true', help="continously run medium-weight auditor verifying consistency in STH and inclusion proofs of new entries")
parser.add_argument('--audit4', action='store_true', help="run one check on one server")
parser.add_argument('--build-sth', action='store_true', help="get all entries and construct STH")
parser.add_argument('--verify-index', default=None, help="Verify a specific index in all logs" )
parser.add_argument('--host', default=None, help="Base URL for CT log")
parser.add_argument('--roots', action='store_true', help="Check accepted root certificates for all logs" )
parser.add_argument('--cur-sth',
                    metavar='file',
                    default=DEFAULT_CUR_FILE,
                    help="File containing current STH (default=%s)" % DEFAULT_CUR_FILE)

timings = {}
errors = []

monitored_domains = [
    # "google.com",
    "preishelden.de",
    "liu.se",
    "nordu.net",
    "symantec.com",
    ".se",
]

class UTC(datetime.tzinfo):
    def utcoffset(self, dt):
      return datetime.timedelta(hours=0)
    def dst(self, dt):
        return datetime.timedelta(0)

def reduce_layer(layer):
    new_layer = []
    while len(layer) > 1:
        e1 = layer.pop(0)
        e2 = layer.pop(0)
        new_layer.append(internal_hash((e1,e2)))
    return new_layer

def reduce_tree(entries, layers):
    if len(entries) == 0 and layers is []:
        return [[hashlib.sha256().digest()]]
  
    layer_idx = 0
    layers[layer_idx] += entries

    while len(layers[layer_idx]) > 1:
        if len(layers) == layer_idx + 1:
            layers.append([])

        layers[layer_idx + 1] += reduce_layer(layers[layer_idx]) 
        layer_idx += 1
    return layers

def reduce_subtree_to_root(layers):
    while len(layers) > 1:
        if len(layers[1]) == 0:
            layers[1] = layers[0]
        else:
            layers[1] += next_merkle_layer(layers[0])
        del layers[0]

    if len(layers[0]) > 1:
        return next_merkle_layer(layers[0])
    return layers[0]

def fetch_all_sth():
    sths = {}
    for base_url in base_urls:
        # Fetch STH
        try:
            sths[base_url] =  get_sth(base_url)
        except:
            sths[base_url] = None
            error_str = time.strftime('%H:%M:%S') + " ERROR: Failed to retrieve STH from " + base_url
            print error_str
            errors.append(error_str)
            continue

        # Check signature on the STH
        try:
            # check_sth_signature(base_url, sths[base_url], logkeys[base_url])
            check_sth_signature(base_url, sths[base_url], None)
        except:
            error_str = time.strftime('%H:%M:%S') + " ERROR: Could not verify signature from " + base_url
            print error_str
            errors.append(error_str)
            continue

    return sths

def verify_progress(old, new):
    print "Verifying progress"
    try:
        for url in new:
            if new and old and new[url] and old[url]:
                if new[url]["tree_size"] == old[url]["tree_size"]:
                    if old[url]["sha256_root_hash"] != new[url]["sha256_root_hash"]:
                        errors.append(time.strftime('%H:%M:%S') + " CRITICAL: root hash is different for same tree size in " + url)
                elif new[url]["tree_size"] < old[url]["tree_size"]:
                        errors.append(time.strftime('%H:%M:%S') + " CRITICAL: new tree smaller than previous tree (%d < %d)" % \
                          (new[url]["tree_size"], old[url]["tree_size"]))
            if new[url]:
                age = time.time() - new[url]["timestamp"]/1000
                sth_time = datetime.datetime.fromtimestamp(new[url]['timestamp'] / 1000, UTC()).strftime("%Y-%m-%d %H:%M:%S")
                roothash = new[url]['sha256_root_hash']
                if age > 24 * 3600:
                    errors.append(time.strftime('%H:%M:%S') + " CRITICAL: %s is older than 24h: %s UTC" % (url, sth_time))
                elif age > 12 * 3600:
                    errors.append(time.strftime('%H:%M:%S') + " WARNING: %s is older than 12h: %s UTC" % (url, sth_time))
                elif age > 6 * 3600:
                    errors.append(time.strftime('%H:%M:%S') + " WARNING: %s is older than 6h: %s UTC" % (url, sth_time))
                # elif age > 2 * 3600:
                #     errors.append(time.strftime('%H:%M:%S') + " WARNING: %s is older than 2h: %s UTC" % (url, sth_time))
    except:
        print time.strftime('%H:%M:%S') + " ERROR: Failed to verify progress for " + url


def verify_consistency(old, new):
    for url in old:
        try:
            if old[url] and new[url] and old[url]["tree_size"]!= new[url]["tree_size"]:
                consistency_proof = get_consistency_proof(url, old[url]["tree_size"], new[url]["tree_size"])
                decoded_consistency_proof = []
                for item in consistency_proof:
                    decoded_consistency_proof.append(base64.b64decode(item))
                res = verify_consistency_proof(decoded_consistency_proof, old[url]["tree_size"], new[url]["tree_size"], old[url]["sha256_root_hash"])
                
                if old[url]["sha256_root_hash"] != str(base64.b64encode(res[0])):
                    print time.strftime('%H:%M:%S') + " Verification of old hash failed! " + old[url]["sha256_root_hash"], str(base64.b64encode(res[0]))
                    errors.append(time.strftime('%H:%M:%S') + " ERROR: Failed to verify consistency for " + url + ", tree size " + old[url]["tree_size"])
                elif new[url]["sha256_root_hash"] != str(base64.b64encode(res[1])):
                    print time.strftime('%H:%M:%S') + " Verification of new hash failed! " + new[url]["sha256_root_hash"], str(base64.b64encode(res[1]))
                    errors.append(time.strftime('%H:%M:%S') + " ERROR: Failed to verify consistency for " + url + ", tree size " + new[url]["tree_size"])
                else:
                    print time.strftime("%H:%M:%S") + " New STH from " + url + ", timestamp: " + \
                        str(new[url]["timestamp"]) + ", size: " + str(new[url]["tree_size"]) + "...OK."

        except:
          print "ERROR: Could not verify consistency for " + url

def verify_inclusion_all(old, new):
    for url in old:
        try:
            if old[url] and new[url]:
                if old[url]["tree_size"]!= new[url]["tree_size"]:
                    entries = []

                    while len(entries) + old[url]["tree_size"]!= new[url]["tree_size"]:
                        entries += get_entries(url, str(int(old[url]["tree_size"]) + len(entries)), new[url]["tree_size"] -1)["entries"]
                        print "Got " + str(len(entries)) + " entries..."

                    success = True
                    for i in entries:
                        h = get_leaf_hash(base64.b64decode(i["leaf_input"]))
                        if not verify_inclusion_by_hash(url, h):
                            success = False

                    if success:
                        print time.strftime("%H:%M:%S") + " Verifying inclusion for " + str(len(entries)) + " new entries in " + url + " ...OK"
                    else:
                        print time.strftime('%H:%M:%S') + " ERROR: Failed to prove inclusion of all new entries in " + url
                        errors.append(time.strftime('%H:%M:%S') + " ERROR: Failed to prove inclusion of all new entries in " + url)
        except:
            print time.strftime('%H:%M:%S') + " ERROR: Failed to prove inclusion of all new entries in " + url
            errors.append(time.strftime('%H:%M:%S') + " ERROR: Failed to prove inclusion of all new entries in " + url)

def check_domain(raw_entry):
    orig_entry = extract_original_entry(raw_entry)
    cert_info = get_cert_info(orig_entry[0][0])
    for md in monitored_domains:
        if md in cert_info["subject"]:
            print md + " (" + cert_info["subject"].split("CN=")[1] + ") certifed by " + cert_info["issuer"]


def fetch_and_increment_subtree(old_sth, new_sth_in, subtree, base_url):
    try:
        sth = old_sth[base_url]
        new_sth = new_sth_in[base_url]
        idx = sth["tree_size"]

        # print time.strftime('%H:%M:%S') + " Getting all entries from " + base_url
        while idx < new_sth["tree_size"]:
            pre_size = idx
            entries = get_entries(base_url, idx, new_sth["tree_size"]-1)["entries"]
            
            new_leafs = []
            for item in entries:
                check_domain(item)
                new_leafs.append(get_leaf_hash(base64.b64decode(item["leaf_input"])))
            idx += len(new_leafs)
            print time.strftime('%H:%M:%S') + " Got entries " + str(pre_size) + " to " + str(idx) + " from " + base_url
            subtree = reduce_tree(new_leafs, subtree)

    except:
        print "Failed to build subtree :("

    return subtree 

def fetch_and_build_subtree(old_sth, base_url):
    try:
        sth = old_sth[base_url]
        subtree = [[]]
        idx = 0

        while idx < sth["tree_size"]:
            pre_size = idx
            entries = get_entries(base_url, idx, sth["tree_size"]-1)["entries"]
            new_leafs = []
            for item in entries:
                check_domain(item)
                new_leafs.append(get_leaf_hash(base64.b64decode(item["leaf_input"])))
            idx += len(new_leafs)
            print time.strftime('%H:%M:%S') + " Got entries " + str(pre_size) + " to " + str(idx) + " from " + base_url
            subtree = reduce_tree(new_leafs, subtree)

    except:
        print "Failed to build subtree :("

    return subtree


def verify_subtree(old_sth, subtree, base_url):
    try:
        sth = old_sth[base_url]
        root = base64.b64encode(reduce_subtree_to_root(subtree)[0])

        if root == sth["sha256_root_hash"]:
            print time.strftime('%H:%M:%S') + " Verifying root hashes for " + base_url + "...OK."
        else:
            print time.strftime('%H:%M:%S') + " ERROR: Failed to verify root hashes! STH root: " + sth["sha256_root_hash"] + ", Tree root: " + root
            errors.append(time.strftime('%H:%M:%S') + " ERROR: Failed to verify root hash for " + base_url + ", tre size " + sth["tree_size"])
    except:
        print time.strftime('%H:%M:%S') + " ERROR: Failed to build STH for " + base_url
        errors.append(time.strftime('%H:%M:%S') + " ERROR: Failed to build STH for " + base_url)

def verify_inclusion_by_hash(base_url, leaf_hash):
    try: 
        tmp_sth = get_sth(base_url)
        proof = get_proof_by_hash(base_url, leaf_hash, tmp_sth["tree_size"])

        decoded_inclusion_proof = []
        for item in proof["audit_path"]:
            decoded_inclusion_proof.append(base64.b64decode(item))
        
        root = base64.b64encode(verify_inclusion_proof(decoded_inclusion_proof, proof["leaf_index"], tmp_sth["tree_size"], leaf_hash))

        if tmp_sth["sha256_root_hash"] == root:
            return True
        else:
            print time.strftime('%H:%M:%S') + " ERROR: Could not prove inclusion for entry " + str(proof["leaf_index"]) + " in " + base_url
            errors.append(time.strftime('%H:%M:%S') + " ERROR: Could not prove inclusion for entry " + str(proof["leaf_index"]) + " in " + base_url)
            return False
    except:
        print time.strftime('%H:%M:%S') + " ERROR: Could not prove inclusion for hashed entry in " + base_url
        errors.append(time.strftime('%H:%M:%S') + " ERROR: Could not prove inclusion for hashed entry in " + base_url)
        return False

def verify_inclusion_by_index(base_url, index):
    try: 
        tmp_sth = get_sth(base_url)
        proof = get_proof_by_index(base_url, index, tmp_sth["tree_size"])

        decoded_inclusion_proof = []
        for item in proof["audit_path"]:
            decoded_inclusion_proof.append(base64.b64decode(item))

        root = base64.b64encode(verify_inclusion_proof(decoded_inclusion_proof, index, tmp_sth["tree_size"], get_leaf_hash(base64.b64decode(proof["leaf_input"]))))

        if tmp_sth["sha256_root_hash"] == root:
            print time.strftime('%H:%M:%S') + " Verifying inclusion for entry " + str(index) + " in " + base_url + "...OK."
        else:
            print time.strftime('%H:%M:%S') + " ERROR: Could not prove inclusion for entry " + str(index) + " in " + base_url
            errors.append(time.strftime('%H:%M:%S') + " ERROR: Could not prove inclusion for entry " + str(index) + " in " + base_url)
    except:
        print time.strftime('%H:%M:%S') + " ERROR: Could not prove inclusion for entry " + str(index) + " in " + base_url
        errors.append(time.strftime('%H:%M:%S') + " ERROR: Could not prove inclusion for entry " + str(index) + " in " + base_url)

def get_proof_by_index(baseurl, index, tree_size):
    try:
        params = urllib.urlencode({"leaf_index":index,
                                   "tree_size":tree_size})
        result = \
          urlopen(baseurl + "ct/v1/get-entry-and-proof?" + params).read()
        return json.loads(result)
    except urllib2.HTTPError, e:
        print "ERROR:", e.read()
        sys.exit(0)

def get_all_roots(base_url):
    result = urlopen(base_url + "ct/v1/get-roots").read()
    certs = json.loads(result)["certificates"]
    print time.strftime('%H:%M:%S') + " Received " + str(len(certs)) + " certs from " + base_url

    for accepted_cert in certs:
        subject = get_cert_info(base64.decodestring(accepted_cert))["subject"]
        issuer = get_cert_info(base64.decodestring(accepted_cert))["issuer"]
        if subject == issuer:
            root_cert = base64.decodestring(accepted_cert)
            print get_cert_info(root_cert)["subject"]

def print_errors(errors):
    print "Encountered " + str(len(errors)) + " errors:"
    for item in errors:
        print item

def print_timings(timings):
    for item in timings:
        m,s = divmod(timings[item]["longest"], 60)
        h,m = divmod(m, 60)
        print item + " last seen " + datetime.datetime.fromtimestamp(int(timings[item]["last"])/1000).strftime('%Y-%m-%d %H:%M:%S') \
            + " longest between two STH: " + str(int(h)) + "h " + str(int(m)) + "m "# + str(int(s)) + "s."

def read_sth(fn):
    try:
        f = open(fn)
    except IOError, e:
        if e.errno == errno.ENOENT:
            return None
        raise e
    return json.loads(f.read())

def write_file(fn, sth):
    tempname = fn + ".new"
    open(tempname, 'w').write(json.dumps(sth))
    mv_file(tempname, fn)

def main(args):
    
    # print time.strftime("%H:%M:%S") + " Starting..."
    if args.verify_index is None and not args.build_sth and not args.audit and not args.audit2 \
        and not args.audit3 and not args.audit4 and not args.roots and not args.monitor:
        
        print time.strftime('%H:%M:%S') + " Nothing to do."
        return
    elif args.audit4:
        pass
    else:
        sth = fetch_all_sth()

    if args.verify_index is not None:
        for url in base_urls:
            verify_inclusion_by_index(url, int(args.verify_index))

    if args.roots:
        print time.strftime('%H:%M:%S') + " Getting accepted Root Certs from all logs..."
        for url in base_urls:
            get_all_roots(url)


    if args.build_sth:
        print time.strftime('%H:%M:%S') + " Building trees from entries. This may take a while, go get coffee or something..."
        for base_url in base_urls:
            subtree = fetch_and_build_subtree(sth, base_url)
            verify_subtree(sth, subtree, base_url)
        # fetch_and_build_tree(sth, base_urls[2])

    if args.audit:
        print time.strftime('%H:%M:%S') + " Running auditor1 for " +str(len(base_urls)) + " logs..."
        old_sth = read_sth(args.cur_sth)
        if old_sth:
            verify_consistency(old_sth, sth)
        else: 
            print "No old sth found..."
        write_file(args.cur_sth, sth)


    if args.audit3:
        print time.strftime('%H:%M:%S') + " Running auditor3 for " +str(len(base_urls)) + " logs..."
        while True:
            time.sleep(30)
            new_sth = fetch_all_sth()
            verify_consistency(sth, new_sth)
            verify_inclusion_all(sth, new_sth)
            sth = new_sth

    if args.audit2:
        print time.strftime('%H:%M:%S') + " Running auditor2 for " +str(len(base_urls)) + " logs..."
        old_sth = read_sth(args.cur_sth)
            # print "Verifying progress..."
        verify_progress(old_sth, sth)
        if old_sth:
            print "Verifying consistency..."
            verify_consistency(old_sth, sth)
            print "Verifying inclusion..."
            verify_inclusion_all(old_sth, sth)
        write_file(args.cur_sth, sth)
    
    # Experimental for plausible + nagios
    if args.audit4:
        base_url = base_urls[0]
        old_sth = read_sth("plausible-sth.json")
        print "Running auditor4 for " + base_url
        try:
            tmp_sth =  get_sth(base_url)
        except:
            error_str = time.strftime('%H:%M:%S') + " ERROR: Failed to retrieve STH from " + base_url
            print error_str
            errors.append(error_str)
            sys.exit(NAGIOS_WARN)

        # Check signature on the STH
        try:
            check_sth_signature(base_url, tmp_sth, None)
            write_file("plausible-sth.json", tmp_sth)
        except:
            error_str = time.strftime('%H:%M:%S') + " ERROR: Could not verify signature from " + base_url
            print error_str
            errors.append(error_str)
            sys.exit(NAGIOS_CRIT)
        sys.exit(NAGIOS_OK)

    if args.monitor:
        # Run for one log only
        all_subtrees = {}
        print time.strftime('%H:%M:%S') + " Building trees from entries. This may take a while, go get coffee or something..."
        for url in base_urls:
            all_subtrees[url] = fetch_and_build_subtree(sth, url)
            verify_subtree(sth, all_subtrees[url], url)
        
        while True:
            time.sleep(30)
            new_sth = fetch_all_sth()
            for url in base_urls:
                if sth[url]["tree_size"] != new_sth[url]["tree_size"]:
                    all_subtrees[url] = fetch_and_increment_subtree(sth, new_sth, all_subtrees[url], url)
                    verify_subtree(sth, all_subtrees[url], url)
                    sth = new_sth


if __name__ == '__main__':
    # try:
        main(parser.parse_args())
        if len(errors) == 0:
            print time.strftime('%H:%M:%S') + " Everything OK."
            sys.exit(NAGIOS_OK)
        else:
            # print "errors found!"
            print_errors(errors)
            sys.exit(NAGIOS_WARN)
    # except:
    #     pass
    # finally:
    #     # print_timings(timings)
    #     print_errors(errors)