Http proxy, string chomp error is nil?

im building a proxy, im having a problem with processing the get request
i recive from the client.

the client will send the proxy the get request and then the proxy sends
out this same request to the servers…

so, when i recieve a request from the client, ill take this header and
strip out the Host: like this

header=“GET / HTTP/1.1
Host: www.google.com
User-Agent: Mozilla/5.0 (Windows NT 5.1Firefox/8.0.1
Accept: text/html,application/xhtml+xml
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Connection: keep-alive”

host = header.to_a[1].chomp[6…-1] => “www.google.com

this works every time in irb testing, but is inconsistent when my script
is running, the proxy works 90% of the time. when www.yahoo.com is
requested the script crashes with Host nil error but when yahoo.com is
request the script works fine…

GET / HTTP/1.1
Host: www.yahoo.com
User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:8.0.1) Gecko/20100101
Firefox/8.0.1
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,/;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Connection: keep-alive
Cookie:
B=8tefbfp77l57r&b=4&d=YTsZzxppYELpjioeXJu1kVafe.sroIDDz5owJg–&s=db&i=AhdUsAlvafAjzjZtkcC1;
F=a=.fI9HRcMvTab.ukb24sGFXCNVEqUnV6kET4hAn3W1si7nfsvB8h_xSSa5wZoY8sju.Bj7s4-&b=e70h;
Y=v=1&n=35d31ktflt3pr&p=;
fpc=d=dZMgXDOItm2f.klxz2sfDYNxkFevm_0AxEXHNXANYwDgrN_qJwqGHO_HqDkoHNxq0pvLiqEAAyWQSqTRNpIu3OGRXqcZJHhFM1qhL2c.5g44dNEYfgRPoOqvbhzgmVRNu3ls8RgDrnajHWeNjMlMjgJL0hKAYP2NgN3WGc2sXKDveE3.iRyd3Rdj2.92W0Aa5JXw_Ak-&v=2;
CH=AgIG0TQcTwn4YAAbrGAAEuBgAA2HYAAwnWAAKZhgAD5KYAAo5DAIGeMwACbxYAAZpGAAIZ4=;
CRZY0=t=bn=0;
fpt=d=vfO8FVTXecx5JjCjNA4wAmkmvxmpDc6Yi4soM9nzzwrVETeqMnlSv6.mPz7ZxDZIIZMRRoNng458dpROFMiVMgMhe75Oa1KxF_mr6SIty4chG2kmCka7ic5aoYek6kpahiH8n1fEGX7b…nLsoVDXFsRRXInysWPDDdgKTz0rUtcHNme6jenB.PEFmRe1LG0FBW_azvS7kZlHCkaFY9KYAEQuMf9ghHzSMNKqR0x4jj3UYZUpo1_1Jl399Y3jdPaE1.3AOlOp_OLiEL4MGlFxJ4I6ngNa6W2rz90_4iYAcda3YxBKMTBIOA_F.XZfqF0HKnikNB3pS1ealSjTWduAxbpcTK93kZkCWFMjD.lqB4njH2rQrxGd._RE0BsVmArPDhYGaGrW4DRH4y94cyZT6zRQ.QONbxHkBT0llvWOWxh5HeOimkRCWk7d00vOGy6ZWaV4UW3ODHRcXJg8ZBqm9AOsCDTQdxtZtUqgR9IQ8mErUUVij1o11BejZKdyfikXQpPePvVdL0j&v=1;
fpc_s=d=QrlkhWXXLB2gA5NNdxa7E0M74Un3.BAO4CVRxPC0gLkU4meLdhn7rhveTTfVD21HxzGEU1hlZ2www.yahoo.com
wE5Lm4lUU96Ukeh_ROc96RcvX9nltXX0NKvDG659Jmpojt1Ndso04VmHdVXa82tVBNpkIBfzYouP5EvvIGbRw72cEYbLAy3WCpT_8qwOdM…ESYE_fPs8aXRvKvxL3rMrHc0XP8BGjOOmal0KCW9BglRpbBOX9MD5IGqIw4ZKFq5HSQssHooX30KaWjFmBd9ot.dYOaifjWL8R5i3q4aqQK4OLvIXKqPxrUujQmPCSrbbdQeU-&v=2;
HP=0

host = header.to_a[1].chomp[6…-1] => nil

Bigmac T. [email protected] wrote:

im building a proxy, im having a problem with processing the get request
i recive from the client.

this works every time in irb testing, but is inconsistent when my script
is running, the proxy works 90% of the time. when www.yahoo.com is
requested the script crashes with Host nil error but when yahoo.com is
request the script works fine…

host = header.to_a[1].chomp[6…-1] => nil

Do you realize that the headers in an HTTP request can come in any
order?
There is absolutely no guarantee that Host: will be first. You’re
relying
on that assumption.

Tim R. wrote in post #1040037:

Bigmac T. [email protected] wrote:

im building a proxy, im having a problem with processing the get request
i recive from the client.

this works every time in irb testing, but is inconsistent when my script
is running, the proxy works 90% of the time. when www.yahoo.com is
requested the script crashes with Host nil error but when yahoo.com is
request the script works fine…

host = header.to_a[1].chomp[6…-1] => nil

Do you realize that the headers in an HTTP request can come in any
order?
There is absolutely no guarantee that Host: will be first. You’re
relying
on that assumption.

I figured this out after testing a few browsers…
here is my little hack for scanning threw a header…

ping = finger.index(“Host:”)
pong = finger.index("\n",ping)
host = finger[ping…pong].gsub(“Host:”,"")

So, i have a stable proxy running, My goal is to place at the top of
every page a banner or advertisement…

send_data_to_client response.sub(""," Hellow world
advertisement")

this works, but the page loads improperly…

so i tried to change the content-length of the packet to zero… I also
tried to increase the size of content-length to make room for my
banner…

so far, the page fails to load properly…

I need more ideas!

Bigmac T. [email protected] wrote:

I figured this out after testing a few browsers…
here is my little hack for scanning threw a header…

ping = finger.index(“Host:”)
pong = finger.index("\n",ping)
host = finger[ping…pong].gsub(“Host:”,"")

So, i have a stable proxy running, My goal is to place at the top of
every page a banner or advertisement…

Your goal is slimy.

send_data_to_client response.sub(""," Hellow world
advertisement")

this works, but the page loads improperly…

The tag lives in the part of the page. There isn’t
supposed
to be anything renderable in the part. You should be looking for
the tag, and insert your slime just after that. If there isn’t
one,
then just shove your slime as the very first thing.

so i tried to change the content-length of the packet to zero… I also
tried to increase the size of content-length to make room for my
banner…

You do need to update Content-Length.

Bigmac T. [email protected] wrote:

i would like to 'shove my slime as the first thing" but i dont see a
control point. how do i know when its the beginning and the end of a
page request… there might be 1 or 30 GET request for one page…

No, there’s only one GET request for the HTML. All the rest of the
requests are for the images and Javascripts and stylesheets. You want
to
modify the text/html request.

Tim R. wrote in post #1040307:

Bigmac T. [email protected] wrote:

I figured this out after testing a few browsers…
here is my little hack for scanning threw a header…

ping = finger.index(“Host:”)
pong = finger.index("\n",ping)
host = finger[ping…pong].gsub(“Host:”,"")

So, i have a stable proxy running, My goal is to place at the top of
every page a banner or advertisement…

Your goal is slimy.

send_data_to_client response.sub(""," Hellow world
advertisement")

this works, but the page loads improperly…

The tag lives in the part of the page. There isn’t
supposed
to be anything renderable in the part. You should be looking for
the tag, and insert your slime just after that. If there isn’t
one,
then just shove your slime as the very first thing.

so i tried to change the content-length of the packet to zero… I also
tried to increase the size of content-length to make room for my
banner…

You do need to update Content-Length.

Ok, i see, with some testing i have been successful with modifying
content-length and adding data… i was doing this in the wrong order,
my algorithm will find the packet that includes content-length and also
includes

i have been testing with alert(“hello world”)…

so, i have been replacing strings like
etc…

i would modify them like this
send response.sub("", "xxxxx).sub(cont_length,cont_length+5)

so, lets say on one page there are 5 packets that include c-length and
also include … then there would be 5 alert messages displayed
when the page loads…

or, like above was said, what if does not exist…

i would like to 'shove my slime as the first thing" but i dont see a
control point. how do i know when its the beginning and the end of a
page request… there might be 1 or 30 GET request for one page…

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