Introduction
============
httplib2 is a comprehensive HTTP client library, httplib2.py supports many
features left out of other HTTP libraries.
### HTTP and HTTPS
HTTPS support is only available if the socket module was
compiled with SSL support.
### Keep-Alive
Supports HTTP 1.1 Keep-Alive, keeping the socket open and
performing multiple requests over the same connection if
possible.
### Authentication
The following three types of HTTP Authentication are
supported. These can be used over both HTTP and HTTPS.
* Digest
* Basic
* WSSE
### Caching
The module can optionally operate with a private cache that
understands the Cache-Control: header and uses both the ETag
and Last-Modified cache validators.
### All Methods
The module can handle any HTTP request method, not just GET
and POST.
### Redirects
Automatically follows 3XX redirects on GETs.
### Compression
Handles both 'deflate' and 'gzip' types of compression.
### Lost update support
Automatically adds back ETags into PUT requests to resources
we have already cached. This implements Section 3.2 of
Detecting the Lost Update Problem Using Unreserved Checkout.
### Unit Tested
A large and growing set of unit tests.
Installation
============
$ pip install httplib2
Usage
=====
A simple retrieval:
```python
import httplib2
h = httplib2.Http(".cache")
(resp_headers, content) = h.request("http://example.org/", "GET")
```
The 'content' is the content retrieved from the URL. The content
is already decompressed or unzipped if necessary.
To PUT some content to a server that uses SSL and Basic authentication:
```python
import httplib2
h = httplib2.Http(".cache")
h.add_credentials('name', 'password')
(resp, content) = h.request("https://example.org/chapter/2",
"PUT", body="This is text",
headers={'content-type':'text/plain'} )
```
Use the Cache-Control: header to control how the caching operates.
```python
import httplib2
h = httplib2.Http(".cache")
(resp, content) = h.request("http://bitworking.org/", "GET")
...
(resp, content) = h.request("http://bitworking.org/", "GET",
headers={'cache-control':'no-cache'})
```
The first request will be cached and since this is a request
to bitworking.org it will be set to be cached for two hours,
because that is how I have my server configured. Any subsequent
GET to that URI will return the value from the on-disk cache
and no request will be made to the server. You can use the
Cache-Control: header to change the caches behavior and in
this example the second request adds the Cache-Control:
header with a value of 'no-cache' which tells the library
that the cached copy must not be used when handling this request.
More example usage can be found at:
* https://github.com/httplib2/httplib2/wiki/Examples
* https://github.com/httplib2/httplib2/wiki/Examples-Python3
### Decompression Limits
To mitigate denial-of-service risks from maliciously crafted compressed responses, the library enforces configurable limits during decompression. Limits are checked in fixed order: **hard limit** → **safe limit** → **ratio**.
- **hard limit**
Absolute maximum decompressed output size (bytes). Exceeding it raises `DecodeLimitError`. Default: `10 GiB`.
- **safe limit**
Output size below which the ratio check is skipped (avoids false positives on small payloads). Default: `10 MiB`.
- **ratio**
Maximum allowed inflation factor (`output_bytes ÷ consumed_input_bytes`). Once output exceeds `safe_limit`, the ratio is enforced. Default: `100`.
- **chunk size**
Internal processing chunk size in bytes (affects granularity of limit checks). Default: `65536` (64 KiB).
Configuration priority (highest first):
1. `Http()` constructor arguments: `decode_limit_hard`, `decode_limit_safe`, `decode_limit_ratio`, `decode_limit_chunk`
2. Environment variables: `httplib2_decode_limit_hard`, `httplib2_decode_limit_safe`, `httplib2_decode_limit_ratio`, `httplib2_decode_limit_chunk` (case-insensitive, uppercase also accepted)
3. Library defaults (listed above)
Example:
```python
h = Http(decode_limit_hard=50_000_000, decode_limit_ratio=50)
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