scapy - fields_desc - add field as offset

up vote
0
down vote

favorite

I'm trying to describe a field as an offset and access it's data

For example:

fields_desc = [LEShortField("structure_size",0),

               ByteField("flags",0),

               **LEShortField("blob_offset",0)**,

               LEFieldLenField("user_name_length", 0),

               LEShortField("user_name_maxlength", 0),

               **LEIntField("user_name_offset", 0)**]

I need to take the variable blob_offset and add it user_name_offset in order to extract the user name.

How can I do it ?? I didn't find and special variable for it...

Thanks

asked 17 hours ago

1337

778

what do you want your packet to look like in the end? do you want user_name to also be a field? do you plan on parsing the entire "blob"?
– AntiMatterDynamite
16 hours ago

yes. I need the user_name as a field. I just don't know where to insert it because it depends on a specific offset...Is it possible?
– 1337
16 hours ago

add a comment |

up vote
0
down vote

favorite

I'm trying to describe a field as an offset and access it's data

For example:

fields_desc = [LEShortField("structure_size",0),

               ByteField("flags",0),

               **LEShortField("blob_offset",0)**,

               LEFieldLenField("user_name_length", 0),

               LEShortField("user_name_maxlength", 0),

               **LEIntField("user_name_offset", 0)**]

I need to take the variable blob_offset and add it user_name_offset in order to extract the user name.

How can I do it ?? I didn't find and special variable for it...

Thanks

asked 17 hours ago

1337

778

what do you want your packet to look like in the end? do you want user_name to also be a field? do you plan on parsing the entire "blob"?
– AntiMatterDynamite
16 hours ago

yes. I need the user_name as a field. I just don't know where to insert it because it depends on a specific offset...Is it possible?
– 1337
16 hours ago

add a comment |

up vote
0
down vote

favorite

I'm trying to describe a field as an offset and access it's data

For example:

fields_desc = [LEShortField("structure_size",0),

               ByteField("flags",0),

               **LEShortField("blob_offset",0)**,

               LEFieldLenField("user_name_length", 0),

               LEShortField("user_name_maxlength", 0),

               **LEIntField("user_name_offset", 0)**]

I need to take the variable blob_offset and add it user_name_offset in order to extract the user name.

How can I do it ?? I didn't find and special variable for it...

Thanks

asked 17 hours ago

1337

778

I'm trying to describe a field as an offset and access it's data

For example:

fields_desc = [LEShortField("structure_size",0),

               ByteField("flags",0),

               **LEShortField("blob_offset",0)**,

               LEFieldLenField("user_name_length", 0),

               LEShortField("user_name_maxlength", 0),

               **LEIntField("user_name_offset", 0)**]

I need to take the variable blob_offset and add it user_name_offset in order to extract the user name.

How can I do it ?? I didn't find and special variable for it...

Thanks

python networking scapy

asked 17 hours ago

1337

778

asked 17 hours ago

1337

778

asked 17 hours ago

1337

778

asked 17 hours ago

1337

778

asked 17 hours ago

1337

778

what do you want your packet to look like in the end? do you want user_name to also be a field? do you plan on parsing the entire "blob"?
– AntiMatterDynamite
16 hours ago

yes. I need the user_name as a field. I just don't know where to insert it because it depends on a specific offset...Is it possible?
– 1337
16 hours ago

add a comment |

what do you want your packet to look like in the end? do you want user_name to also be a field? do you plan on parsing the entire "blob"?
– AntiMatterDynamite
16 hours ago

yes. I need the user_name as a field. I just don't know where to insert it because it depends on a specific offset...Is it possible?
– 1337
16 hours ago

what do you want your packet to look like in the end? do you want user_name to also be a field? do you plan on parsing the entire "blob"?
– AntiMatterDynamite
16 hours ago

yes. I need the user_name as a field. I just don't know where to insert it because it depends on a specific offset...Is it possible?
– 1337
16 hours ago

add a comment |

1 Answer
1

active

oldest

votes

up vote
0
down vote

well you don't exactly say how your packet looks, assuming your "blob" and username are right after the packet you already specified you can try to do something like this:

fields_desc = [LEShortField("structure_size",0),

               ByteField("flags",0),

               LEFieldLenField("blob_offset",0, length_of="blob_offset_pad", fmt="!H"),

               LEFieldLenField("user_name_length", 0, length_of="user_name"),

               LEShortField("user_name_maxlength", 0),

               LEFieldLenField("user_name_offset", 0, length_of="user_name", fmt="!I"),

               StrFixedLenField("blob_offset_pad", 0, length_from = lambda pkt: pkt.blob_offset),

               StrFixedLenField("user_name_offset_pad", 0, length_from = lambda pkt: pkt.user_name_offset),

               StrFixedLenField("user_name", "", length_from= lambda pkt: pkt.user_name_length)]

again can't really test this because you didn't provide any useful examples

answered 14 hours ago

AntiMatterDynamite

828212

add a comment |

Your Answer

StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");

StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});

function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});

}
});

draft saved

draft discarded

Sign up or log in

StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});

Post as a guest

Name

Required, but never shown

StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53371195%2fscapy-fields-desc-add-field-as-offset%23new-answer', 'question_page');
}
);

Post as a guest

Name

Required, but never shown

1 Answer
1

active

oldest

votes

1 Answer
1

active

oldest

votes

up vote
0
down vote

well you don't exactly say how your packet looks, assuming your "blob" and username are right after the packet you already specified you can try to do something like this:

fields_desc = [LEShortField("structure_size",0),

               ByteField("flags",0),

               LEFieldLenField("blob_offset",0, length_of="blob_offset_pad", fmt="!H"),

               LEFieldLenField("user_name_length", 0, length_of="user_name"),

               LEShortField("user_name_maxlength", 0),

               LEFieldLenField("user_name_offset", 0, length_of="user_name", fmt="!I"),

               StrFixedLenField("blob_offset_pad", 0, length_from = lambda pkt: pkt.blob_offset),

               StrFixedLenField("user_name_offset_pad", 0, length_from = lambda pkt: pkt.user_name_offset),

               StrFixedLenField("user_name", "", length_from= lambda pkt: pkt.user_name_length)]

again can't really test this because you didn't provide any useful examples

answered 14 hours ago

AntiMatterDynamite

828212

add a comment |

up vote
0
down vote

well you don't exactly say how your packet looks, assuming your "blob" and username are right after the packet you already specified you can try to do something like this:

fields_desc = [LEShortField("structure_size",0),

               ByteField("flags",0),

               LEFieldLenField("blob_offset",0, length_of="blob_offset_pad", fmt="!H"),

               LEFieldLenField("user_name_length", 0, length_of="user_name"),

               LEShortField("user_name_maxlength", 0),

               LEFieldLenField("user_name_offset", 0, length_of="user_name", fmt="!I"),

               StrFixedLenField("blob_offset_pad", 0, length_from = lambda pkt: pkt.blob_offset),

               StrFixedLenField("user_name_offset_pad", 0, length_from = lambda pkt: pkt.user_name_offset),

               StrFixedLenField("user_name", "", length_from= lambda pkt: pkt.user_name_length)]

again can't really test this because you didn't provide any useful examples

answered 14 hours ago

AntiMatterDynamite

828212

add a comment |

up vote
0
down vote

well you don't exactly say how your packet looks, assuming your "blob" and username are right after the packet you already specified you can try to do something like this:

fields_desc = [LEShortField("structure_size",0),

               ByteField("flags",0),

               LEFieldLenField("blob_offset",0, length_of="blob_offset_pad", fmt="!H"),

               LEFieldLenField("user_name_length", 0, length_of="user_name"),

               LEShortField("user_name_maxlength", 0),

               LEFieldLenField("user_name_offset", 0, length_of="user_name", fmt="!I"),

               StrFixedLenField("blob_offset_pad", 0, length_from = lambda pkt: pkt.blob_offset),

               StrFixedLenField("user_name_offset_pad", 0, length_from = lambda pkt: pkt.user_name_offset),

               StrFixedLenField("user_name", "", length_from= lambda pkt: pkt.user_name_length)]

again can't really test this because you didn't provide any useful examples

answered 14 hours ago

AntiMatterDynamite

828212

well you don't exactly say how your packet looks, assuming your "blob" and username are right after the packet you already specified you can try to do something like this:

fields_desc = [LEShortField("structure_size",0),

               ByteField("flags",0),

               LEFieldLenField("blob_offset",0, length_of="blob_offset_pad", fmt="!H"),

               LEFieldLenField("user_name_length", 0, length_of="user_name"),

               LEShortField("user_name_maxlength", 0),

               LEFieldLenField("user_name_offset", 0, length_of="user_name", fmt="!I"),

               StrFixedLenField("blob_offset_pad", 0, length_from = lambda pkt: pkt.blob_offset),

               StrFixedLenField("user_name_offset_pad", 0, length_from = lambda pkt: pkt.user_name_offset),

               StrFixedLenField("user_name", "", length_from= lambda pkt: pkt.user_name_length)]

again can't really test this because you didn't provide any useful examples

answered 14 hours ago

AntiMatterDynamite

828212

answered 14 hours ago

AntiMatterDynamite

828212

answered 14 hours ago

AntiMatterDynamite

828212

answered 14 hours ago

AntiMatterDynamite

828212

add a comment |

draft saved

draft discarded

draft saved

draft discarded

Sign up or log in

StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});

Post as a guest

Name

Required, but never shown

Post as a guest

Name

Required, but never shown

Sign up or log in

StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});

Post as a guest

Name

Required, but never shown

Sign up or log in

StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});

Post as a guest

Name

Required, but never shown

Sign up or log in

StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});

Post as a guest

Name

Required, but never shown

Name

Required, but never shown

Name

Required, but never shown

This page is only for reference, If you need detailed information, please check here

搜尋此網誌

Ytukyg