local nmap = require "nmap"
local os = require "os"
local shortport = require "shortport"
local sslcert = require "sslcert"
local stdnse = require "stdnse"
local string = require "string"

description = [[
Retrieves a server's SSL certificate. The amount of information printed
about the certificate depends on the verbosity level. With no extra
verbosity, the script prints the validity period and the commonName,
organizationName, stateOrProvinceName, and countryName of the subject.

<code>
443/tcp open  https
| ssl-cert: Subject: commonName=www.paypal.com/organizationName=PayPal, Inc.\
/stateOrProvinceName=California/countryName=US
| Not valid before: 2011-03-23 00:00:00
|_Not valid after:  2013-04-01 23:59:59
</code>

With <code>-v</code> it adds the issuer name and fingerprints.

<code>
443/tcp open  https
| ssl-cert: Subject: commonName=www.paypal.com/organizationName=PayPal, Inc.\
/stateOrProvinceName=California/countryName=US
| Issuer: commonName=VeriSign Class 3 Extended Validation SSL CA\
/organizationName=VeriSign, Inc./countryName=US
| Public Key type: rsa
| Public Key bits: 2048
| Not valid before: 2011-03-23 00:00:00
| Not valid after:  2013-04-01 23:59:59
| MD5:   bf47 ceca d861 efa7 7d14 88ad 4a73 cb5b
|_SHA-1: d846 5221 467a 0d15 3df0 9f2e af6d 4390 0213 9a68
</code>

With <code>-vv</code> it adds the PEM-encoded contents of the entire
certificate.

<code>
443/tcp open  https
| ssl-cert: Subject: commonName=www.paypal.com/organizationName=PayPal, Inc.\
/stateOrProvinceName=California/countryName=US/1.3.6.1.4.1.311.60.2.1.2=Delaware\
/postalCode=95131-2021/localityName=San Jose/serialNumber=3014267\
/streetAddress=2211 N 1st St/1.3.6.1.4.1.311.60.2.1.3=US\
/organizationalUnitName=PayPal Production/businessCategory=Private Organization
| Issuer: commonName=VeriSign Class 3 Extended Validation SSL CA\
/organizationName=VeriSign, Inc./countryName=US\
/organizationalUnitName=Terms of use at https://www.verisign.com/rpa (c)06
| Public Key type: rsa
| Public Key bits: 2048
| Not valid before: 2011-03-23 00:00:00
| Not valid after:  2013-04-01 23:59:59
| MD5:   bf47 ceca d861 efa7 7d14 88ad 4a73 cb5b
| SHA-1: d846 5221 467a 0d15 3df0 9f2e af6d 4390 0213 9a68
| -----BEGIN CERTIFICATE-----
| MIIGSzCCBTOgAwIBAgIQLjOHT2/i1B7T//819qTJGDANBgkqhkiG9w0BAQUFADCB
...
| 9YDR12XLZeQjO1uiunCsJkDIf9/5Mqpu57pw8v1QNA==
|_-----END CERTIFICATE-----
</code>
]]

---
-- @output
-- 443/tcp open  https
-- | ssl-cert: Subject: commonName=www.paypal.com/organizationName=PayPal, Inc.\
-- /stateOrProvinceName=California/countryName=US
-- | Not valid before: 2011-03-23 00:00:00
-- |_Not valid after:  2013-04-01 23:59:59
--
-- @xmloutput
-- <table key="subject">
--   <elem key="1.3.6.1.4.1.311.60.2.1.2">Delaware</elem>
--   <elem key="1.3.6.1.4.1.311.60.2.1.3">US</elem>
--   <elem key="postalCode">95131-2021</elem>
--   <elem key="localityName">San Jose</elem>
--   <elem key="serialNumber">3014267</elem>
--   <elem key="countryName">US</elem>
--   <elem key="stateOrProvinceName">California</elem>
--   <elem key="streetAddress">2211 N 1st St</elem>
--   <elem key="organizationalUnitName">PayPal Production</elem>
--   <elem key="commonName">www.paypal.com</elem>
--   <elem key="organizationName">PayPal, Inc.</elem>
--   <elem key="businessCategory">Private Organization</elem>
-- </table>
-- <table key="issuer">
--   <elem key="organizationalUnitName">Terms of use at https://www.verisign.com/rpa (c)06</elem>
--   <elem key="organizationName">VeriSign, Inc.</elem>
--   <elem key="commonName">VeriSign Class 3 Extended Validation SSL CA</elem>
--   <elem key="countryName">US</elem>
-- </table>
-- <table key="pubkey">
--   <elem key="type">rsa</elem>
--   <elem key="bits">2048</elem>
-- </table>
-- <table key="validity">
--   <elem key="notBefore">2011-03-23T00:00:00+00:00</elem>
--   <elem key="notAfter">2013-04-01T23:59:59+00:00</elem>
-- </table>
-- <elem key="md5">bf47cecad861efa77d1488ad4a73cb5b</elem>
-- <elem key="sha1">d8465221467a0d153df09f2eaf6d439002139a68</elem>
-- <elem key="pem">-----BEGIN CERTIFICATE-----
-- MIIGSzCCBTOgAwIBAgIQLjOHT2/i1B7T//819qTJGDANBgkqhkiG9w0BAQUFADCB
-- ...
-- 9YDR12XLZeQjO1uiunCsJkDIf9/5Mqpu57pw8v1QNA==
-- -----END CERTIFICATE-----
-- </elem>

author = "David Fifield"

license = "Same as Nmap--See http://nmap.org/book/man-legal.html"

categories = { "default", "safe", "discovery" }


portrule = function(host, port)
    return shortport.ssl(host, port) or sslcert.isPortSupported(port)
end

-- Find the index of a value in an array.
function table_find(t, value)
    local i, v
    for i, v in ipairs(t) do
        if v == value then
            return i
        end
    end
    return nil
end

function date_to_string(date)
    if not date then
        return "MISSING"
    end
    if type(date) == "string" then
        return string.format("Can't parse; string is \"%s\"", date)
    else
        return stdnse.format_timestamp(stdnse.date_to_timestamp(date, 0), 0)
    end
end

-- These are the subject/issuer name fields that will be shown, in this order,
-- without a high verbosity.
local NON_VERBOSE_FIELDS = { "commonName", "organizationName",
    "stateOrProvinceName", "countryName" }

function stringify_name(name)
    local fields = {}
    local _, k, v
    if not name then
        return nil
    end
    for _, k in ipairs(NON_VERBOSE_FIELDS) do
        v = name[k]
        if v then
            fields[#fields + 1] = string.format("%s=%s", k, v)
        end
    end
    if nmap.verbosity() > 1 then
        for k, v in pairs(name) do
            -- Don't include a field twice.
            if not table_find(NON_VERBOSE_FIELDS, k) then
                if type(k) == "table" then
                    k = stdnse.strjoin(".", k)
                end
                fields[#fields + 1] = string.format("%s=%s", k, v)
            end
        end
    end
    return stdnse.strjoin("/", fields)
end

local function name_to_table(name)
  local output = {}
  for k, v in pairs(name) do
    if type(k) == "table" then
      k = stdnse.strjoin(".", k)
    end
    output[k] = v
  end
  return output
end

local function output_tab(cert)
    local o = stdnse.output_table()
    o.subject = name_to_table(cert.subject)
    o.issuer = name_to_table(cert.issuer)
    o.pubkey = cert.pubkey
    o.validity = {}
    for k, v in pairs(cert.validity) do
      if type(v)=="string" then
        o.validity[k] = v
      else
        o.validity[k] = stdnse.format_timestamp(stdnse.date_to_timestamp(v, 0), 0)
      end
    end
    o.md5 = stdnse.tohex(cert:digest("md5"))
    o.sha1 = stdnse.tohex(cert:digest("sha1"))
    o.pem = cert.pem
    return o
end

local function output_str(cert)
    local lines = {}

    lines[#lines + 1] = "Subject: " .. stringify_name(cert.subject)

    if nmap.verbosity() > 0 then
        lines[#lines + 1] = "Issuer: " .. stringify_name(cert.issuer)
    end

    if nmap.verbosity() > 0 then
        lines[#lines + 1] = "Public Key type: " .. cert.pubkey.type
        lines[#lines + 1] = "Public Key bits: " .. cert.pubkey.bits
    end

    lines[#lines + 1] = "Not valid before: " ..
        date_to_string(cert.validity.notBefore)
    lines[#lines + 1] = "Not valid after:  " ..
        date_to_string(cert.validity.notAfter)

    if nmap.verbosity() > 0 then
        lines[#lines + 1] = "MD5:   " .. stdnse.tohex(cert:digest("md5"), { separator = " ", group = 4 })
        lines[#lines + 1] = "SHA-1: " .. stdnse.tohex(cert:digest("sha1"), { separator = " ", group = 4 })
    end

    if nmap.verbosity() > 1 then
        lines[#lines + 1] = cert.pem
    end
    return stdnse.strjoin("\n", lines)
end

action = function(host, port)
    local status, cert = sslcert.getCertificate(host, port)
    if ( not(status) ) then
        return
    end

    return output_tab(cert), output_str(cert)
end



