Add: support for HTTP/2 (#1610)

* Add: support for HTTP/2

See NASL manual documentation.

Jira: SC-1038

`openvas-nasl -X -t example.com http2.nasl`

```
h = http2_handle();
display(h);

r = http2_get(handle:h, port:443, item:"/", schema:"https");
display("response: ", r);
rc = http2_get_response_code(handle:h);
display("return code: ", rc);

http2_close_handle(h);

h = http2_handle();
display(h);

r = http2_get(handle:h, port:3000, item:"/vts", schema:"http");
display("response: ", r);
rc = http2_get_response_code(handle:h);
display("return code: ", rc);

http2_close_handle(h);
```

* nasl/nasl_http2.c

* small fix reported by clippy non related to this PR's topic

* fix typos

Author: jjnicola

doc/manual/nasl/built-in-functions/http2-functions/http2_close_handle.md

@@ -0,0 +1,30 @@
+# http2_close_handle
+
+## NAME
+
+**http2_close_handle** - Close a handle for http requests previously initialized.
+
+## SYNOPSIS
+
+*void* **http_close_handle**(handle: *int*);
+
+**http_close_handle** takes one argument.
+
+## DESCRIPTION
+ Close a handle for http requests previously initialized.
+
+## RETURN VALUE
+It returns an integer or NULL on error.
+
+## EXAMPLES
+
+**1** Close the handle identifier
+```cpp
+h = http2_handle();
+display(h);
+http2_close_handle(h);
+```
+
+## SEE ALSO
+
+**[http2_delete(3)](http2_delete.md)**, **[http2_get(3)](http2_get.md)**, **[http2_close_handle(3)](http2_close_handle.md)**, **[http2_head(3)](http2_head.md)**, **[http2_handle(3)](http2_handle.md)**, **[http2_post(3)](http2_post.md)**, **[http2_put(3)](http2_put.md)**, **[http2_get_response_code(3)](http2_get_response_code.md)**, **[http2_set_custom_header(3)](http2_set_custom_header.md)**

doc/manual/nasl/built-in-functions/http2-functions/http2_delete.md

@@ -0,0 +1,37 @@
+# http2_delete
+
+## NAME
+
+**http2_delete** - performs an HTTP2 DELETE request for the server on the port.
+
+## SYNOPSIS
+
+*void* **http_delete**(handle: *int*, port: *int*, schema: *string*, item: *string*, data: *string*);
+
+**http_delete** takes five named arguments.
+
+## DESCRIPTION
+Performs an HTTP2 DELETE request for the server on the port. It tries to force the version HTTP2 if `https` (default) is passed as schema uses ALPN to negotiate the protocol to use.
+
+If `http` is passed as schema, the function includes an upgrade header in the initial request to the host to allow upgrading to HTTP/2.
+The arguments are port and item (the path, query, etc), schema (optional, defualt `https`) and `data` (optional).
+
+## RETURN VALUE
+It returns a string (the http response). Null on error
+
+## EXAMPLES
+
+**1** Delete and display the formatted delete request:
+```cpp
+h = http2_handle();
+display(h);
+
+r = http2_delete(handle:h, port:3000, item:"/vts", schema:"http");
+display("response: ", r);
+rc = http2_get_response_code(handle:h);
+display("return code: ", rc);
+```
+
+## SEE ALSO
+
+**[http2_delete(3)](http2_delete.md)**, **[http2_get(3)](http2_get.md)**, **[http2_close_handle(3)](http2_close_handle.md)**, **[http2_head(3)](http2_head.md)**, **[http2_handle(3)](http2_handle.md)**, **[http2_post(3)](http2_post.md)**, **[http2_put(3)](http2_put.md)**, **[http2_get_response_code(3)](http2_get_response_code.md)**, **[http2_set_custom_header(3)](http2_set_custom_header.md)**

doc/manual/nasl/built-in-functions/http2-functions/http2_get.md

@@ -0,0 +1,37 @@
+# http2_get
+
+## NAME
+
+**http2_get** - performs an HTTP2 GET request for the server on the port.
+
+## SYNOPSIS
+
+*void* **http_get**(handle: *int*, port: *int*, schema: *string*, item: *string*, data: *string*);
+
+**http_get** takes five named arguments.
+
+## DESCRIPTION
+Performs an HTTP2 GET request for the server on the port. It tries to force the version HTTP2 if `https` (default) is passed as schema uses ALPN to negotiate the protocol to use.
+
+If `http` is passed as schema, the function includes an upgrade header in the initial request to the host to allow upgrading to HTTP/2.
+The arguments are port and item (the path, query, etc), schema (optional, defualt `https`) and `data` (optional).
+
+## RETURN VALUE
+It returns a string (the http response). Null on error
+
+## EXAMPLES
+
+**1** Get and display the formatted get request:
+```cpp
+h = http2_handle();
+display(h);
+
+r = http2_get(handle:h, port:3000, item:"/vts", schema:"http");
+display("response: ", r);
+rc = http2_get_response_code(handle:h);
+display("return code: ", rc);
+```
+
+## SEE ALSO
+
+**[http2_delete(3)](http2_delete.md)**, **[http2_get(3)](http2_get.md)**, **[http2_close_handle(3)](http2_close_handle.md)**, **[http2_head(3)](http2_head.md)**, **[http2_handle(3)](http2_handle.md)**, **[http2_post(3)](http2_post.md)**, **[http2_put(3)](http2_put.md)**, **[http2_get_response_code(3)](http2_get_response_code.md)**, **[http2_set_custom_header(3)](http2_set_custom_header.md)**

doc/manual/nasl/built-in-functions/http2-functions/http2_get_response_code.md

@@ -0,0 +1,34 @@
+# http2_get_response_code
+
+## NAME
+
+**http2_get_response_code** - Gets the response code
+
+## SYNOPSIS
+
+*void* **http2_get_response_code**(handle: *int*);
+
+**http_get** takes one argument.
+
+## DESCRIPTION
+After performing a request, is possible to get the response code calling this function and giving the handle identifier.
+
+## RETURN VALUE
+It returns an intenger with the response code. Null on error
+
+## EXAMPLES
+
+**1** Get and display the response code:
+```cpp
+h = http2_handle();
+display(h);
+
+r = http2_get(handle:h, port:3000, item:"/vts", schema:"http");
+display("response: ", r);
+rc = http2_get_response_code(handle:h);
+display("return code: ", rc);
+```
+
+## SEE ALSO
+
+**[http2_delete(3)](http2_delete.md)**, **[http2_get(3)](http2_get.md)**, **[http2_close_handle(3)](http2_close_handle.md)**, **[http2_head(3)](http2_head.md)**, **[http2_handle(3)](http2_handle.md)**, **[http2_post(3)](http2_post.md)**, **[http2_put(3)](http2_put.md)**, **[http2_get_response_code(3)](http2_get_response_code.md)**, **[http2_set_custom_header(3)](http2_set_custom_header.md)**

doc/manual/nasl/built-in-functions/http2-functions/http2_handle.md

@@ -0,0 +1,29 @@
+# http2_handle
+
+## NAME
+
+**http2_handle** - Creates a handle for http requests.
+
+## SYNOPSIS
+
+*void* **http_handle**();
+
+**http_handle** takes no argument.
+
+## DESCRIPTION
+Initialize a handle for performing http requests.
+
+## RETURN VALUE
+It returns an integer or NULL on error.
+
+## EXAMPLES
+
+**1** Get the handle identifier
+```cpp
+h = http2_handle();
+display(h);
+```
+
+## SEE ALSO
+
+**[http2_delete(3)](http2_delete.md)**, **[http2_get(3)](http2_get.md)**, **[http2_close_handle(3)](http2_close_handle.md)**, **[http2_head(3)](http2_head.md)**, **[http2_handle(3)](http2_handle.md)**, **[http2_post(3)](http2_post.md)**, **[http2_put(3)](http2_put.md)**, **[http2_get_response_code(3)](http2_get_response_code.md)**, **[http2_set_custom_header(3)](http2_set_custom_header.md)**

doc/manual/nasl/built-in-functions/http2-functions/http2_head.md

@@ -0,0 +1,37 @@
+# http2_head
+
+## NAME
+
+**http2_head** - performs an HTTP2 HEAD request for the server on the port.
+
+## SYNOPSIS
+
+*void* **http_head**(handle: *int*, port: *int*, schema: *string*, item: *string*, data: *string*);
+
+**http_head** takes five named arguments.
+
+## DESCRIPTION
+Performs an HTTP2 HEAD request for the server on the port. It tries to force the version HTTP2 if `https` (default) is passed as schema uses ALPN to negotiate the protocol to use.
+
+If `http` is passed as schema, the function includes an upgrade header in the initial request to the host to allow upgrading to HTTP/2.
+The arguments are port and item (the path, query, etc), schema (optional, defualt `https`) and `data` (optional).
+
+## RETURN VALUE
+It returns a string (the http response). Null on error
+
+## EXAMPLES
+
+**1** Get and display the formatted head request:
+```cpp
+h = http2_handle();
+display(h);
+
+r = http2_head(handle:h, port:3000, item:"/", schema:"http");
+display("response: ", r);
+rc = http2_get_response_code(handle:h);
+display("return code: ", rc);
+```
+
+## SEE ALSO
+
+**[http2_delete(3)](http2_delete.md)**, **[http2_get(3)](http2_get.md)**, **[http2_close_handle(3)](http2_close_handle.md)**, **[http2_head(3)](http2_head.md)**, **[http2_handle(3)](http2_handle.md)**, **[http2_post(3)](http2_post.md)**, **[http2_put(3)](http2_put.md)**, **[http2_get_response_code(3)](http2_get_response_code.md)**, **[http2_set_custom_header(3)](http2_set_custom_header.md)**

doc/manual/nasl/built-in-functions/http2-functions/http2_post.md

@@ -0,0 +1,37 @@
+# http2_post
+
+## NAME
+
+**http2_post** - performs an HTTP2 POST request for the server on the port.
+
+## SYNOPSIS
+
+*void* **http_post**(handle: *int*, port: *int*, schema: *string*, item: *string*, data: *string*);
+
+**http_post** takes five named arguments.
+
+## DESCRIPTION
+Performs an HTTP2 POST request for the server on the port. It tries to force the version HTTP2 if `https` (default) is passed as schema uses ALPN to negotiate the protocol to use.
+
+If `http` is passed as schema, the function includes an upgrade header in the initial request to the host to allow upgrading to HTTP/2.
+The arguments are port and item (the path, query, etc), schema (optional, defualt `https`) and `data` (optional).
+
+## RETURN VALUE
+It returns a string (the http response). Null on error
+
+## EXAMPLES
+
+**1** Get and display the formatted post request:
+```cpp
+h = http2_handle();
+display(h);
+
+r = http2_post(handle:h, port:3000, item:"/scan", schema:"http", data:"bad scan config format");
+display("response: ", r);
+rc = http2_get_response_code(handle:h);
+display("return code: ", rc);
+```
+
+## SEE ALSO
+
+**[http2_delete(3)](http2_delete.md)**, **[http2_get(3)](http2_get.md)**, **[http2_close_handle(3)](http2_close_handle.md)**, **[http2_head(3)](http2_head.md)**, **[http2_handle(3)](http2_handle.md)**, **[http2_post(3)](http2_post.md)**, **[http2_put(3)](http2_put.md)**, **[http2_get_response_code(3)](http2_get_response_code.md)**, **[http2_set_custom_header(3)](http2_set_custom_header.md)**

doc/manual/nasl/built-in-functions/http2-functions/http2_put.md

@@ -0,0 +1,37 @@
+# http2_put
+
+## NAME
+
+**http2_put** - performs an HTTP2 PUT request for the server on the port.
+
+## SYNOPSIS
+
+*void* **http_put**(handle: *int*, port: *int*, schema: *string*, item: *string*, data: *string*);
+
+**http_put** takes five named arguments.
+
+## DESCRIPTION
+Performs an HTTP2 PUT request for the server on the port. It tries to force the version HTTP2 if `https` (default) is passed as schema uses ALPN to negotiate the protocol to use.
+
+If `http` is passed as schema, the function includes an upgrade header in the initial request to the host to allow upgrading to HTTP/2.
+The arguments are port and item (the path, query, etc), schema (optional, defualt `https`) and `data` (optional).
+
+## RETURN VALUE
+It returns a string (the http response). Null on error
+
+## EXAMPLES
+
+**1** Get and display the formatted put request:
+```cpp
+h = http2_handle();
+display(h);
+
+r = http2_put(handle:h, port:3000, item:"/scan", schema:"http", data:"bad scan config format");
+display("response: ", r);
+rc = http2_get_response_code(handle:h);
+display("return code: ", rc);
+```
+
+## SEE ALSO
+
+**[http2_delete(3)](http2_delete.md)**, **[http2_get(3)](http2_get.md)**, **[http2_close_handle(3)](http2_close_handle.md)**, **[http2_head(3)](http2_head.md)**, **[http2_handle(3)](http2_handle.md)**, **[http2_post(3)](http2_post.md)**, **[http2_put(3)](http2_put.md)**, **[http2_get_response_code(3)](http2_get_response_code.md)**, **[http2_set_custom_header(3)](http2_set_custom_header.md)**

doc/manual/nasl/built-in-functions/http2-functions/http2_set_custom_header.md

@@ -0,0 +1,30 @@
+# http2_set_custom_header
+
+## NAME
+
+**http2_set_custom_header** - Set a custom header element in the header
+
+## SYNOPSIS
+
+*void* **http_set_custom_header**(handle: *int*, header_item: *string*);
+
+**http_set_custom_header** takes two arguments.
+
+## DESCRIPTION
+Adds a new element to initialized handle header.
+
+## RETURN VALUE
+It returns an integer or NULL on error.
+
+## EXAMPLES
+
+**1** Set a new element in the header
+```cpp
+h = http2_handle();
+display(h);
+http2_set_custom_header(handle: h, handle_item: "Content-Type: application/json");
+```
+
+## SEE ALSO
+
+**[http2_delete(3)](http2_delete.md)**, **[http2_get(3)](http2_get.md)**, **[http2_close_handle(3)](http2_close_handle.md)**, **[http2_head(3)](http2_head.md)**, **[http2_handle(3)](http2_handle.md)**, **[http2_post(3)](http2_post.md)**, **[http2_put(3)](http2_put.md)**, **[http2_get_response_code(3)](http2_get_response_code.md)**, **[http2_set_custom_header(3)](http2_set_custom_header.md)**

doc/manual/nasl/built-in-functions/http2-functions/index.md

@@ -0,0 +1,16 @@
+# HTTP2 Functions
+
+## GENERAL
+
+These functions are mainly used for performing HTTP2 request.
+
+## TABLE OF CONTENT
+- **[http2_handle](http2_handle.md)** - Creates a handle for http requests.
+- **[http2_close_handle](http2_close_handle.md)** - Close a handle for http requests previously initialized.
+- **[http2_get_response_code](http2_get_response_code.md)** - Get the http response code after performing a HTTP request.
+- **[http2_set_custom_header](http2_set_custom_header.md)** - Set a custom header element in the header.
+- **[http2_delete](http2_delete.md)** - performs an HTTP2 DELETE request for the server on the port.
+- **[http2_get](http2_get.md)** - performs an HTTP2 DELETE request for the server on the port.
+- **[http2_head](http2_head.md)** - performs an HTTP2 HEAD request for the server on the port.
+- **[http2_post](http2_post.md)** - performs an HTTP2 POST request for the server on the port.
+- **[http2_put](http2_put.md)** - performs an HTTP2 PUT request for the server on the port.