urlparser1.c - simple URL parser
Posted by Anonymous on Wed 24th Jan 2024 10:29
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/*
 * MIT License
 *
 * Copyright (c) 2024 Roland Mainz <roland.mainz@nrubsig.org>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <stdio.h>

/*
 * Original extended regular expression:
 *
 * "^"
 * "(.+?)"                       // scheme
 * "://"                         // '://'
 * "("                           // login
 *       "(?:"
 *               "(.+?)"         // user (optional)
 *               "(?::(.+))?"    // password (optional)
 *               "@"
 *       ")?"
 *       "("                     // hostport
 *               "(.+?)"         // host
 *               "(?::([[:digit:]]+))?" // port (optional)
 *       ")"
 * ")"
 * "(?:/(.*?))?"                 // path (optional)
 * "$"
 */

typedef
struct _url_parser_context {
        char *in_url;

        char *scheme;
        struct {
                char *login;
        } login;
        struct {
                char *hostname;
                signed int port;
        } hostport;
        char *path;
} url_parser_context;

url_parser_context *url_parser_create_context(const char *in_url)
{
        url_parser_context *uctx;
        char *s;
        size_t in_url_len;
        size_t context_len;

        if (!in_url)
                return NULL;

        in_url_len = strlen(in_url);

        context_len = sizeof(url_parser_context) +
                ((in_url_len+1)*5);
        uctx = malloc(context_len);
        if (!uctx)
                return NULL;

        s = (void *)(uctx+1);
        uctx->in_url = s;       s+= in_url_len+1;
        (void)strcpy(uctx->in_url, in_url);
        uctx->scheme = s;       s+= in_url_len+1;
        uctx->login.login = s;  s+= in_url_len+1;
        uctx->hostport.hostname = s;    s+= in_url_len+1;
        uctx->path = s; s+= in_url_len+1;

        return uctx;
}

int url_parser(url_parser_context *uctx)
{
        (void)fprintf(stderr, "## parser in_url='%s'\n", uctx->in_url);

        char *s;
        const char *urlstr = uctx->in_url;
        size_t slen;

        s = strstr(urlstr, "://");
        if (!s) {
                (void)fprintf(stderr, "url_parser: Not an URL\n");
                return -1;
        }

        slen = s-urlstr;
        (void)memcpy(uctx->scheme, urlstr, slen);
        uctx->scheme[slen] = '\0';
        urlstr += slen + 3;

        (void)fprintf(stdout, "scheme='%s', rest='%s'\n", uctx->scheme, urlstr);

        s = strstr(urlstr, "@");
        if (s) {
                /* URL has user/password */
                slen = s-urlstr;
                (void)memcpy(uctx->login.login, urlstr, slen);
                uctx->login.login[slen] = '\0';
                urlstr += slen + 1;

                (void)fprintf(stdout, "login='%s', rest='%s'\n", uctx->login.login, urlstr);
        }
        else
        {
                uctx->login.login = NULL;
        }

        s = strstr(urlstr, "/");
        if (s) {
                /* URL has hostport */
                slen = s-urlstr;
                (void)memcpy(uctx->hostport.hostname, urlstr, slen);
                uctx->hostport.hostname[slen] = '\0';
                urlstr += slen + 1;

                (void)fprintf(stdout, "hostport='%s', rest='%s'\n", uctx->hostport.hostname, urlstr);

                s = strstr(uctx->hostport.hostname, ":");
                if (s) {
                        /* found port number */
                        uctx->hostport.port = atoi(s+1);
                        *s = '\0';
                }
                else
                {
                        uctx->hostport.port = -1;
                }


                (void)fprintf(stdout, "hostport='%s', port=%d, rest='%s'\n",
                        uctx->hostport.hostname,
                        uctx->hostport.port,
                        urlstr);
        }
        else
        {
                (void)strcpy(uctx->hostport.hostname, urlstr);
                uctx->path = NULL;
                urlstr = NULL;
        }

        if (!urlstr) {
                return 0;
        }

        (void)strcpy(uctx->path, urlstr);
        (void)fprintf(stdout, "path='%s'\n", uctx->path);

        return 0;
}

void test_url_parser(const char *instr)
{
        url_parser_context *c;

        c = url_parser_create_context(instr);

        url_parser(c);
}

int main(int ac, char *av[])
{
        (void)puts("#start");

        (void)setvbuf(stdout, NULL, _IONBF, 0);
        (void)setvbuf(stderr, NULL, _IONBF, 0);

        (void)test_url_parser("foo://hostbar/baz");
        (void)test_url_parser("foo://myuser@hostbar/baz");
        (void)test_url_parser("foo://myuser:passwd@hostbar/baz");
        (void)test_url_parser("foo://myuser:passwd@hostbar:666/baz");
        (void)test_url_parser("foo://hostbar");
        (void)test_url_parser("foo://hostbar:93");
        (void)test_url_parser("typo:/hostbar");
        (void)test_url_parser("wrong");

        (void)puts("#done");

        return EXIT_SUCCESS;
}