Handling HTTP Requests¶
Add or Modify an HTTP Header¶
You may want to add some extra HTTP header to the response.
In this example we’ll be adding the header X-Content-Type-Options
to the response.
1 2 3 4 5 6 7 8 9 | $ cat sniff.pow
kapow route add /sec-hello-world - <<-'EOF'
kapow set /response/headers/X-Content-Type-Options nosniff
kapow set /response/headers/Content-Type text/plain
echo this will be interpreted as plain text | kapow set /response/body
EOF
$ kapow server nosniff.pow
|
Testing with curl:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 | $ curl -v http://localhost:8080/sec-hello-world
* Trying ::1...
* TCP_NODELAY set
* Connected to localhost (::1) port 8080 (#0)
> GET /sec-hello-word HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.54.0
> Accept: */*
>
< HTTP/1.1 200 OK
< X-Content-Type-Options: nosniff
< Date: Wed, 20 Nov 2019 10:56:46 GMT
< Content-Length: 24
< Content-Type: text/plain
<
this will be interpreted as plain text
|
Warning
Please be aware that if you don’t explicitly specify the value of
the Content-Type
header, Kapow! will guess it, effectively
negating the effect of the X-Content-Type-Options
header.
Note
You can read more about the X-Content-Type-Options: nosniff
header here.
Upload Files¶
Example #1¶
Uploading a file using Kapow! is very simple:
1 2 3 4 | $ cat upload.pow
kapow route add -X POST /upload-file - <<-'EOF'
kapow get /request/files/data/content | kapow set /response/body
EOF
|
1 2 3 4 | $ cat results.json
{"hello": "world"}
$ curl -X POST -H 'Content-Type: multipart/form-data' -F data=@results.json http://localhost:8080/upload-file
{"hello": "world"}
|
Example #2¶
In this example we reply the line count of the file received in the request:
1 2 3 4 5 6 7 8 9 10 11 12 13 | $ cat count-file-lines.pow
kapow route add -X POST /count-file-lines - <<-'EOF'
# Get sent file
FNAME=$(kapow get /request/files/myfile/filename)
# Counting file lines
LCOUNT=$(kapow get /request/files/myfile/content | wc -l)
kapow set /response/status 200
echo "$FNAME has $LCOUNT lines" | kapow set /response/body
EOF
|
1 2 3 4 5 | $ cat file.txt
hello
World
$ curl -F myfile=@file.txt http://localhost:8080/count-file-lines
file.txt has 2 lines
|
Sending HTTP error codes¶
You can specify custom status code for HTTP
response:
1 2 3 4 5 | $ cat error.pow
kapow route add /error - <<-'EOF'
kapow set /response/status 401
echo -n '401 error' | kapow set /response/body
EOF
|
Testing with curl:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | $ curl -v http://localhost:8080/error
* Trying ::1...
* TCP_NODELAY set
* Connected to localhost (::1) port 8080 (#0)
> GET /error HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.54.0
> Accept: */*
>
< HTTP/1.1 401 Unauthorized
< Date: Wed, 20 Nov 2019 14:06:44 GMT
< Content-Length: 10
< Content-Type: text/plain; charset=utf-8
<
401 error
|
How to redirect using HTTP¶
In this example we’ll redirect our users to Google
:
1 2 3 4 5 | $ cat redirect.pow
kapow route add /redirect - <<-'EOF'
kapow set /response/headers/Location https://google.com
kapow set /response/status 301
EOF
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | $ curl -v http://localhost:8080/redirect
* Trying ::1...
* TCP_NODELAY set
* Connected to localhost (::1) port 8080 (#0)
> GET /redirect HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.54.0
> Accept: */*
>
< HTTP/1.1 301 Moved Permanently
< Location: http://google.com
< Date: Wed, 20 Nov 2019 11:39:24 GMT
< Content-Length: 0
<
* Connection #0 to host localhost left intact
|
Manage Cookies¶
If you track down some user state, Kapow! allows you manage Request/Response Cookies.
In the next example we’ll set a cookie:
1 2 3 4 5 6 7 8 9 10 | $ cat cookie.pow
kapow route add /setcookie - <<-'EOF'
CURRENT_STATUS=$(kapow get /request/cookies/kapow-status)
if [ -z "$CURRENT_STATUS" ]; then
kapow set /response/cookies/Kapow-Status 'Kapow Cookie Set'
fi
echo -n OK | kapow set /response/body
EOF
|
Calling with curl:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | $ curl -v http://localhost:8080/setcookie
* Trying ::1...
* TCP_NODELAY set
* Connected to localhost (::1) port 8080 (#0)
> GET /setcookie HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.54.0
> Accept: */*
>
< HTTP/1.1 200 OK
< Set-Cookie: Kapow-Status="Kapow Cookie Set"
< Date: Fri, 22 Nov 2019 10:44:42 GMT
< Content-Length: 3
< Content-Type: text/plain; charset=utf-8
<
OK
* Connection #0 to host localhost left intact
|