Encoding URI and URI Component in C++

README.md

Encode and Decode HTTP URIs and URI components in C++

What is a URI?

A Uniform Resource Identifier (URI) is a string of characters that unambiguously identifies a particular resource. To guarantee uniformity, all URIs follow a predefined set of syntax rules,[1] but also maintain extensibility through a separately defined hierarchical naming scheme (e.g. "http://").

Such identification enables interaction with representations of the resource over a network, typically the World Wide Web, using specific protocols. Schemes specifying a concrete syntax and associated protocols define each URI. The most common form of URI is the Uniform Resource Locator (URL), frequently referred to informally as a web address. More rarely seen in usage is the Uniform Resource Name (URN), which was designed to complement URLs by providing a mechanism for the identification of resources in particular namespaces.

The common parts of a URI are described below.

 foo://example.com:8042/over/there?name=ferret#nose
 \_/   \______________/\_________/ \_________/ \__/
  |           |            |            |        |
scheme     authority       path        query   fragment

There are 5 parts in a URI:

• scheme: the scheme of the URI (related to protocol stuff, ex: http, https, ftp...).
• authority: in URLs, they are composed of 3 parts.
• path: the path to the resource being accessed.
• query: key-value pairs with relevant encoded information to the server.
• fragment: information that is not sent to the process.

In the authority there are 3 parts:

john:[email protected]:8042
\______/ \_________/ \__/
    |         |        |
userinfo    host     port

• userinfo: relevant information to an authentication
• host: the domain name of the resource
• port: The TCP port that the resource is being served

What is the difference between a URI and a URI component?

And URI is what we described earlier. A URI component is a string sequence that can encode a URI inside a URI.

decoding a string like this

http://google.com/path?key=http://google.com

would be ambiguous, so the relevant characters like:, /, @, =, & and # are encoded to avoid ambiguity while decoding.

How to use this header

it's simple just copy and paste encode.h to your includes directory and add #include "encode.h" to your sources and use the function as you wish.

encode.h

#ifndef ENCODE_H_
#define ENCODE_H_

std::string decodeURIComponent(std::string encoded) {

    std::string decoded = encoded;
    std::smatch sm;
    std::string haystack;

    int dynamicLength = decoded.size() - 2;

    if (decoded.size() < 3) return decoded;

    for (int i = 0; i < dynamicLength; i++)
    {

        haystack = decoded.substr(i, 3);

        if (std::regex_match(haystack, sm, std::regex("%[0-9A-F]{2}")))
        {
            haystack = haystack.replace(0, 1, "0x");
            std::string rc = {(char)std::stoi(haystack, nullptr, 16)};
            decoded = decoded.replace(decoded.begin() + i, decoded.begin() + i + 3, rc);
        }

        dynamicLength = decoded.size() - 2;

    }

    return decoded;
}

std::string encodeURIComponent(std::string decoded)
{

    std::ostringstream oss;
    std::regex r("[!'\\(\\)*-.0-9A-Za-z_~]");

    for (char &c : decoded)
    {
        if (std::regex_match((std::string){c}, r))
        {
            oss << c;
        }
        else
        {
            oss << "%" << std::uppercase << std::hex << (0xff & c);
        }
    }
    return oss.str();
}

#endif

Could you provide also decoding functions ? I think this could improve your gist. Thank you.

I know this is old, but I found a bug. Single hex digit values are not padded out with a zero.

Line 47 should read:

oss << "%" << std::uppercase << std::setw(2) << std::setfill('0') << std::hex << (int)(c & 0xff);

Thanks!! El lun, 20 may 2024, 16:41, Mark Manyen ***@***.***> escribió:

…

***@***.**** commented on this gist. ------------------------------ I know this is old, but I found a bug. Single hex digit values are not padded out with a zero. Line 47 should read: oss << "%" << std::uppercase << std::setw(2) << std::setfill('0') << std::hex << (int)(c & 0xff); — Reply to this email directly, view it on GitHub <https://gist.github.com/arthurafarias/56fec2cd49a32f374c02d1df2b6c350f#gistcomment-5063168> or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABPZAFFUW6E32W2PNJVGUPLZDIDTFBFKMF2HI4TJMJ2XIZLTSKBKK5TBNR2WLJDUOJ2WLJDOMFWWLO3UNBZGKYLEL5YGC4TUNFRWS4DBNZ2F6YLDORUXM2LUPGBKK5TBNR2WLJDHNFZXJJDOMFWWLK3UNBZGKYLEL52HS4DFVRZXKYTKMVRXIX3UPFYGLK2HNFZXIQ3PNVWWK3TUUZ2G64DJMNZZDAVEOR4XAZNEM5UXG5FFOZQWY5LFVA4TKMJZGQ2TSNVHORZGSZ3HMVZKMY3SMVQXIZI> . You are receiving this email because you authored the thread. Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub> .