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Improved error handling (and messages) on dhcp-discover.nse. Hoping to track down a problem reported to me by Brandon Enright.

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ron
2010-04-07 21:03:51 +00:00
parent 4332937a74
commit 398ecbcb62
1 changed files with 17 additions and 11 deletions
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28
scripts/dhcp-discover.nse
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@@ -112,7 +112,7 @@ end
local function read_ip(data, pos, length)
if(length ~= 4) then
if((length % 4) ~= 0) then
stdnse.print_debug("dhcp-discover: Invalid length for an ip address (%d)", length)
stdnse.print_debug(1, "dhcp-discover: Invalid length for an ip address (%d)", length)
pos = pos + length
return pos, nil
@@ -154,7 +154,7 @@ end
--@return The value of the field, or nil if the field length was wrong.
local function read_1_byte(data, pos, length)
if(length ~= 1) then
stdnse.print_debug("dhcp-discover: Invalid length for data (%d; should be %d)", length, 1)
stdnse.print_debug(1, "dhcp-discover: Invalid length for data (%d; should be %d)", length, 1)
pos = pos + length
return pos, nil
end
@@ -174,6 +174,7 @@ local function read_message_type(data, pos, length)
pos, value = read_1_byte(data, pos, length)
if(value == nil) then
stdnse.print_debug(1, "dhcp-discover: Couldn't read the 1-byte message type")
return pos, nil
end
@@ -193,6 +194,7 @@ local function read_boolean(data, pos, length)
pos, result = read_1_byte(data, pos, length)
if(result == nil) then
stdnse.print_debug(1, "dhcp-discover: Couldn't read the 1-byte boolean")
return nil
elseif(result == 0) then
return "false"
@@ -210,7 +212,7 @@ end
--@return The value of the field, or nil if the field length was wrong.
local function read_2_bytes(data, pos, length)
if(length ~= 2) then
stdnse.print_debug("dhcp-discover: Invalid length for data (%d; should be %d)", length, 2)
stdnse.print_debug(1, "dhcp-discover: Invalid length for data (%d; should be %d)", length, 2)
pos = pos + length
return pos, nil
end
@@ -228,7 +230,7 @@ end
--@return The value of the field, or nil if the field length was wrong.
local function read_2_bytes_list(data, pos, length)
if((length % 2) ~= 0) then
stdnse.print_debug("dhcp-discover: Invalid length for data (%d; should be multiple of %d)", length, 2)
stdnse.print_debug(1, "dhcp-discover: Invalid length for data (%d; should be multiple of %d)", length, 2)
pos = pos + length
return pos, nil
@@ -254,7 +256,7 @@ end
--@return The value of the field, or nil if the field length was wrong.
local function read_4_bytes(data, pos, length)
if(length ~= 4) then
stdnse.print_debug("dhcp-discover: Invalid length for data (%d; should be %d)", length, 4)
stdnse.print_debug(1, "dhcp-discover: Invalid length for data (%d; should be %d)", length, 4)
pos = pos + length
return pos, nil
end
@@ -272,7 +274,7 @@ end
local function read_time(data, pos, length)
local result
if(length ~= 4) then
stdnse.print_debug("dhcp-discover: Invalid length for data (%d; should be %d)", length, 4)
stdnse.print_debug(1, "dhcp-discover: Invalid length for data (%d; should be %d)", length, 4)
pos = pos + length
return pos, nil
end
@@ -308,7 +310,7 @@ end
--@return The value of the field, or nil if the field length was wrong.
local function read_static_route(data, pos, length)
if((length % 8) ~= 0) then
stdnse.print_debug("dhcp-discover: Invalid length for data (%d; should be multiple of %d)", length, 8)
stdnse.print_debug(1, "dhcp-discover: Invalid length for data (%d; should be multiple of %d)", length, 8)
pos = pos + length
return pos, nil
@@ -335,7 +337,7 @@ end
--@return The value of the field, or nil if the field length was wrong.
local function read_policy_filter(data, pos, length)
if((length % 8) ~= 0) then
stdnse.print_debug("dhcp-discover: Invalid length for data (%d; should be multiple of %d)", length, 8)
stdnse.print_debug(1, "dhcp-discover: Invalid length for data (%d; should be multiple of %d)", length, 8)
pos = pos + length
return pos, nil
@@ -544,7 +546,7 @@ local function dhcp_parse(data)
-- Verify we got a valid code (if we didn't, we're probably in big trouble)
if(action == nil) then
stdnse.print_debug("dhcp-discover: Unknown option: %d", option)
stdnse.print_debug(1, "dhcp-discover: Unknown option: %d", option)
pos = pos + length
else
-- Call the function to parse the option, and insert the result into our results table
@@ -554,7 +556,11 @@ local function dhcp_parse(data)
stdnse.print_debug(1, "dhcp-discover: Server returned unrequested option (%s => %s)", action['name'], value)
else
table.insert(result['options'], {name=action['name'], value=value})
if(value) then
table.insert(result['options'], {name=action['name'], value=value})
else
stdnse.print_debug(1, "dhcp-discover: Couldn't determine value for %s", action['name']);
end
end
end
@@ -605,7 +611,7 @@ local function go(host, port)
-- Create a pcap socket to listen for the response (this is a HUGE hack. TODO: Fix once I can set the source port)
pcap = nmap.new_socket()
pcap:pcap_open(host.interface, 590, 0, callback, "udp port 68")
stdnse.print_debug("dhcp-discover: Setting socket timeout to %ds", timeout)
stdnse.print_debug(1, "dhcp-discover: Setting socket timeout to %ds", timeout)
pcap:set_timeout(timeout)
-- Create the UDP socket