netw.c

#include "netw.h"

#include <stdlib.h>


static bool
is_unreserved(char x)
{
	// clang-format off
	return (x >= 'A' && x <= 'Z')
		|| (x >= 'a' && x <= 'z')
		|| (x >= '0' && x <= '9')
		|| x == '-'
		|| x == '_'
		|| x == '.'
		|| x == '~';
	// clang-format on
}


char *
netw_percent_encode(char const *input, size_t len, size_t *out_len)
{
	size_t nlen = 0;
	for (size_t i = 0; i < len; ++i)
	{
		nlen += is_unreserved(input[i]) ? 1 : 3;
	}

	char const nibbles[] = "0123456789ABCDEF";

	char *output = malloc(nlen + 1); // NUL terminate
	char *o = output;
	for (size_t i = 0; i < len; ++i)
	{
		if (is_unreserved(input[i]))
		{
			*(o++) = input[i];
		}
		else
		{
			*(o++) = '%';
			*(o++) = nibbles[(input[i] >> 4) & 0xf];
			*(o++) = nibbles[input[i] & 0xf];
		}
	}
	*o = '\0';

	if (out_len)
	{
		*out_len = (size_t)(o - output);
	}

	return output;
}