Create docs/ folder with initial content

Add more documentation on the following topics:
* Running `curl-impersonate` from the command line, including changing
the HTTP headers when needed.
* Using `libcurl-impersonate` in JS and PHP scripts.

README.md

@@ -61,6 +61,10 @@ Please note that the wrapper scripts use a default set of HTTP headers. If you w
 
 See [Advanced usage](#Advanced-usage) for more options, including using `libcurl-impersonate` as a library.
 
+## Documentation
+
+More documentation is available in the [docs/](docs/README.md) directory.
+
 ## Installation
 There are two versions of `curl-impersonate` for technical reasons. The **chrome** version is used to impersonate Chrome, Edge and Safari. The **firefox** version is used to impersonate Firefox.
 

docs/01_GETTING_STARTED.md

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+# Getting started with curl-impersonate
+
+curl-impersonate can be run on Linux and macOS. Partial support for Windows is currently available through a different project: [curl-impersonate-win](https://github.com/depler/curl-impersonate-win).
+
+## Installation
+Installation instructions are available on the [main page](README.md#installation).
+
+The project supplies two modified flavors of curl:
+* The *Chrome version* is a modified curl binary and libcurl library that can impersonate Chrome, Edge and Safari. It uses BoringSSL, Chrome's TLS library. It is based on a patched curl version with added support for some additional TLS extensions and modified HTTP/2 settings that make it look like a browser.
+* The *Firefox version* is a modified curl binary that can impersonate Firefox. It uses NSS, Mozilla's TLS library which is used by Firefox.

docs/02_USAGE.md

@@ -0,0 +1,72 @@
+# Running curl-impersonate from the command line
+
+curl-impersonate can be run from the command line just like the regular curl tool.
+Since it is just a modified curl build, all the original flags and command line options are supported.
+
+For example, the Firefox version can be run as follows:
+```bash
+curl-impersonate-ff -v -L httsp://wikipedia.org
+```
+
+and the Chrome version:
+```bash
+curl-impersonate-chrome -v -L httsp://wikipedia.org
+```
+
+However, by default, running the binaries as above will not prdouce the same TLS and HTTP/2 signatures as the impersonated browsers. Rather, this project provides additional *wrapper scripts* that launch these binaries with the correct set of command line flags to produce the desired signatures. For example:
+```bash
+curl_chrome104 -v -L https://wikipedia.org
+```
+
+will produce a signature identical to Chrome version 104. You can add command line flags and they will be passed on to curl. However, some flags change curl's TLS signature. See below for more details.
+
+The full list of wrapper scripts is available on the [main page](README.md#supported-browsers).
+
+## Changing the HTTP headers
+The wrapper scripts use a certain set of HTTP headers such as `User-Agent`, `Accept-Encoding` and a few more.
+These headers were chosen to be identical to the default set of headers used by the browser upon requesting an unvisited website. The order of the headers was chosen to match as well.
+
+In many different scenarios you may wish to change the headers, their order, or to add new ones.
+To do so correctly, currently the best option is to modify the scripts.
+Otherwise you may get duplicate headers or a wrong order of headers.
+
+## How the wrapper scripts work
+Let's analyze the contents of the `curl_chrome104` wrapper script.
+Understanding this can help in some scenarios where better control of the signature is needed.
+
+The important part of the script is:
+```bash
+"$dir/curl-impersonate-chrome" \
+    --ciphers TLS_AES_128_GCM_SHA256,TLS_AES_256_GCM_SHA384,TLS_CHACHA20_POLY1305_SHA256,ECDHE-ECDSA-AES128-GCM-SHA256,ECDHE-RSA-AES128-GCM-SHA256,ECDHE-ECDSA-AES256-GCM-SHA384,ECDHE-RSA-AES256-GCM-SHA384,ECDHE-ECDSA-CHACHA20-POLY1305,ECDHE-RSA-CHACHA20-POLY1305,ECDHE-RSA-AES128-SHA,ECDHE-RSA-AES256-SHA,AES128-GCM-SHA256,AES256-GCM-SHA384,AES128-SHA,AES256-SHA \
+    -H 'sec-ch-ua: "Chromium";v="104", " Not A;Brand";v="99", "Google Chrome";v="104"' \
+    -H 'sec-ch-ua-mobile: ?0' \
+    -H 'sec-ch-ua-platform: "Windows"' \
+    -H 'Upgrade-Insecure-Requests: 1' \
+    -H 'User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36' \
+    -H 'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9' \
+    -H 'Sec-Fetch-Site: none' \
+    -H 'Sec-Fetch-Mode: navigate' \
+    -H 'Sec-Fetch-User: ?1' \
+    -H 'Sec-Fetch-Dest: document' \
+    -H 'Accept-Encoding: gzip, deflate, br' \
+    -H 'Accept-Language: en-US,en;q=0.9' \
+    --http2 --false-start --compressed \
+    --tlsv1.2 --no-npn --alps \
+    --cert-compression brotli \
+    "$@"
+```
+
+The important flags are as follows:
+* `--ciphers` controls the cipher list, an important part of the TLS client hello message. The ciphers were chosen to match Chrome's.
+* The multiple `-H` flags set the HTTP headers. You may want to modify these in many scenarios where other HTTP headers are required.
+* `--tlsv1.2` sets the minimal TLS version, which is part of the TLS client hello message, to TLS1.2.
+* `--no-npn` disables to NPN TLS extension.
+* `--alps` enables the ALPS TLS extension. This flag was added for this project.
+* `--cert-compression` enables TLS certificate compression used by Chrome. This flag was added for this project. 
+
+## Flags that modify the TLS signature
+
+The following flags are known to affect the TLS signature of curl.
+Using them in addition to the flags in the wrapper scripts may produce a signature that does not match the browser.
+
+`--ciphers`, `--curves`, `--no-npn`, `--no-alpn`, `--tls-max`, `--tls13-ciphers`, `--tlsv1.0`, `--tlsv1.1`, `--tlsv1.2`, `--tlsv1.3`, `--tlsv1` 

docs/03_LIBCURL_IMPERSONATE.md

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+# Using libcurl-impersonate
+
+Documentation for using libcurl-impersonate is currently on the [main page](README.md#libcurl-impersonate).

docs/03_LIBCURL_IMPERSONATE_JS.md

@@ -0,0 +1,3 @@
+# Using libcurl-impersonate in JS scripts
+
+It is possible to make the `node-libcurl` package work with libcurl-impersonate instead of libcurl. Instructions are currently available in [Issue #80](https://github.com/lwthiker/curl-impersonate/issues/80).

docs/03_LIBCURL_IMPERSONATE_PHP.md

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+# Using libcurl-impersonate in PHP scripts
+
+It is possible to use libcurl-impersonate in PHP scripts instead of the original libcurl. PHP loads libcurl dynamically during runtime, which means that a different set of steps needs to be taken.
+
+## On Linux
+
+First, patch libcurl-impersonate and change its SONAME:
+```bash
+patchelf --set-soname libcurl.so.4 /path/to/libcurl-impersonate-chrome.so
+```
+
+Then replace at runtime with:
+```bash
+LD_PRELOAD=/path/to/libcurl-impersonate-chrome.so CURL_IMPERSONATE=chrome101 php -r 'print_r(curl_version());'
+```
+
+If successful you should see:
+```
+[ssl_version] => BoringSSL
+```
+(or NSS if the Firefox version is used)
+
+## On macOS
+
+On Mac, first rename `libcurl-impersonate-chrome.dylib` to `libcurl.4.dylib` and place in some directory, say `/usr/local/lib`. Then run php with the `DYLD_LIBRARY_PATH` env var pointing to that directory, for example:
+```
+DYLD_LIBRARY_PATH=/usr/local/lib php -r 'print_r(curl_version());'
+```
+
+If successful you should see:
+```
+[ssl_version] => BoringSSL
+```

docs/README.md

@@ -0,0 +1,15 @@
+# curl-impersonate documentation
+
+curl-impersonate is a curl build that lets you send HTTP requests that look like a browser's.
+curl-impersonate can impersonate recent versions of Chrome, Edge, Safari & Firefox.
+
+curl-impersonate can be used either as a command line tool, similar to the regular curl, or as a library that can be integrated instead of the regular libcurl.
+These docs describe the various usage options.
+
+## Contents
+
+1. [Getting Started](docs/01_GETTING_STARTED.md)
+2. [Running from the command line](docs/02_USAGE.md)
+3. [Using libcurl-impersonate](docs/03_LIBCURL_IMPERSONATE.md)
+    1. [In PHP scripts](docs/03_LIBCURL_IMPERSONATE_PHP.md)
+    2. [In JS scripts](docs/03_LIBCURL_IMPERSONATE_JS.md)