mirror of https://github.com/omar-polo/gmid.git
427 lines
8.4 KiB
C
427 lines
8.4 KiB
C
/*
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* Copyright (c) 2020 Omar Polo <op@omarpolo.com>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <ctype.h>
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#include <string.h>
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#include "gmid.h"
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/*
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* Notes from RFC3986
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*
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* => gemini://tanso.net/rfc/rfc3986.txt
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*
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*
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* ABNF
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* ====
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*
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* pct-encoded "%" HEXDIG HEXDIG
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*
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* reserved = gen-delims / sub-delimis
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* gen-delims = ":" / "/" / "?" / "#" / "[" / "]" / "@"
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* sub-delims = "!" / "$" / "&" / "'" / "(" / ")"
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* / "*" / "+" / "," / ";" / "="
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*
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* unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~"
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*
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* URI = scheme ":" hier-part [ "?" query ] [ "#" fragment ]
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*
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* hier-part = "//" authority path-abempty
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* / path-absolute
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* / path-rootless
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* / path-empty
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*
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* scheme = ALPHA *( ALPHA / DIGIT / "+" / "-" / "." )
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*
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* authority = [ userinfo "@" ] host [ ":" port ]
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*
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* (note that userinfo isn't used for Gemini URL)
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*
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* host = IP-literal / IPv4address / reg-name
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* reg-name = *( unreserved / pct-encoded / sub-delims )
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*
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* port = *DIGIT
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*
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* path = path-abemty ; begins with "/" or is empty
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* / path-absolute ; begins with "/" but not "//"
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* / path-noscheme ; begins with a non-colon segment
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* / path-rootless ; begins with a segment
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* / path-empty ; zero characters
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*
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* path-abemty = *( "/" segment )
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* path-absolute = "/" [ segment-nz *( "/" segment ) ]
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* path-noscheme = ; not used
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* path-rootless = ; not used
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* path-empty = ; not used
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*
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* segment = *pchar
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* segment-nz = 1*pchar
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* segment-nz-nc = 1*( unreserved / pct-encoded / sub-delims / "@" )
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* pchar = unreserved / pct-encoded / sub-delims / ":" / "@"
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*
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* query = *( pchar / "/" / "?" )
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*
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* fragment = *( pchar / "/" / "?" )
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*
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*
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* EXAMPLE
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* =======
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*
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* foo://example.com:8042/over/there?name=ferret#nose
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* \_/ \______________/\_________/ \_________/ \__/
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* | | | | |
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* scheme authority path query fragment
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*
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*/
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static inline int
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unreserved(int p)
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{
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return isalnum(p)
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|| p == '-'
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|| p == '.'
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|| p == '_'
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|| p == '~';
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}
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static inline int
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sub_delimiters(int p)
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{
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return p == '!'
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|| p == '$'
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|| p == '&'
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|| p == '\''
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|| p == '('
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|| p == ')'
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|| p == '*'
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|| p == '+'
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|| p == ','
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|| p == ';'
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|| p == '=';
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}
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static int
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parse_pct_encoded(struct parser *p)
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{
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if (*p->uri != '%')
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return 0;
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if (!isxdigit(*(p->uri+1)) || !isxdigit(*(p->uri+2))) {
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p->err = "illegal percent-encoding";
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return 0;
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}
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sscanf(p->uri+1, "%2hhx", p->uri);
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memmove(p->uri+1, p->uri+3, strlen(p->uri+3)+1);
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if (*p->uri == '\0') {
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p->err = "illegal percent-encoding";
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return 0;
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}
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return 1;
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}
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/* ALPHA *( ALPHA / DIGIT / "+" / "-" / "." ) "://" */
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static int
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parse_scheme(struct parser *p)
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{
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p->parsed->schema = p->uri;
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if (!isalpha(*p->uri)) {
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p->err = "illegal character in scheme";
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return 0;
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}
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p->uri++;
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while (isalnum(*p->uri)
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|| *p->uri == '+'
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|| *p->uri == '-'
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|| *p->uri == '.')
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p->uri++;
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if (*p->uri != ':') {
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p->err = "illegal character in scheme";
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return 0;
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}
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*p->uri = '\0';
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if (*(++p->uri) != '/' || *(++p->uri) != '/') {
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p->err = "invalid marker after scheme";
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return 0;
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}
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p->uri++;
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return 1;
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}
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/* *DIGIT */
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static int
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parse_port(struct parser *p)
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{
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uint32_t i = 0;
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p->parsed->port = p->uri;
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for (; isdigit(*p->uri); p->uri++) {
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i = i * 10 + *p->uri - '0';
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if (i > UINT16_MAX) {
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p->err = "port number too large";
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return 0;
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}
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}
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if (*p->uri != '/' && *p->uri != '\0') {
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p->err = "illegal character in port number";
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return 0;
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}
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p->parsed->port_no = i;
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if (*p->uri != '\0') {
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*p->uri = '\0';
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p->uri++;
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}
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return 1;
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}
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/* TODO: add support for ip-literal and ipv4addr ? */
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/* *( unreserved / sub-delims / pct-encoded ) */
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static int
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parse_authority(struct parser *p)
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{
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p->parsed->host = p->uri;
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while (unreserved(*p->uri)
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|| sub_delimiters(*p->uri)
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|| parse_pct_encoded(p))
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p->uri++;
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if (p->err != NULL)
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return 0;
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if (*p->uri == ':') {
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*p->uri = '\0';
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p->uri++;
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return parse_port(p);
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}
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if (*p->uri == '/') {
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*p->uri = '\0';
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p->uri++;
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return 1;
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}
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if (*p->uri == '\0')
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return 1;
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p->err = "illegal character in authority section";
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return 0;
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}
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/* Routine for path_clean. Elide the pointed .. with the preceding
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* element. Return 0 if it's not possible. incr is the length of
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* the increment, 3 for ../ and 2 for .. */
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static int
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path_elide_dotdot(char *path, char *i, int incr)
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{
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char *j;
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if (i == path)
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return 0;
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for (j = i-2; j != path && *j != '/'; j--)
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/* noop */ ;
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if (*j == '/')
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j++;
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i += incr;
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memmove(j, i, strlen(i)+1);
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return 1;
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}
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/*
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* Use an algorithm similar to the one implemented in go' path.Clean:
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*
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* 1. Replace multiple slashes with a single slash
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* 2. Eliminate each . path name element
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* 3. Eliminate each inner .. along with the non-.. element that precedes it
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* 4. Eliminate trailing .. if possible or error (go would only discard)
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*
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* Unlike path.Clean, this function return the empty string if the
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* original path is equivalent to "/".
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*/
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static int
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path_clean(char *path)
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{
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char *i;
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/* 1. replace multiple slashes with a single one */
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for (i = path; *i; ++i) {
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if (*i == '/' && *(i+1) == '/') {
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memmove(i, i+1, strlen(i)); /* move also the \0 */
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i--;
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}
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}
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/* 2. eliminate each . path name element */
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for (i = path; *i; ++i) {
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if ((i == path || *i == '/') && *(i+1) == '.' &&
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*(i+2) == '/') {
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/* move also the \0 */
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memmove(i, i+2, strlen(i)-1);
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i--;
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}
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}
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if (!strcmp(path, ".") || !strcmp(path, "/.")) {
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*path = '\0';
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return 1;
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}
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/* 3. eliminate each inner .. along with the preceding non-.. */
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for (i = strstr(path, "../"); i != NULL; i = strstr(path, ".."))
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if (!path_elide_dotdot(path, i, 3))
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return 0;
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/* 4. eliminate trailing ..*/
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if ((i = strstr(path, "..")) != NULL)
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if (!path_elide_dotdot(path, i, 2))
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return 0;
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return 1;
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}
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static int
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parse_query(struct parser *p)
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{
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p->parsed->query = p->uri;
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if (*p->uri == '\0')
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return 1;
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while (unreserved(*p->uri)
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|| sub_delimiters(*p->uri)
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|| *p->uri == '/'
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|| *p->uri == '?'
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|| parse_pct_encoded(p)
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|| valid_multibyte_utf8(p))
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p->uri++;
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if (p->err != NULL)
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return 0;
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if (*p->uri != '\0' && *p->uri != '#') {
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p->err = "illegal character in query";
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return 0;
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}
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if (*p->uri != '\0') {
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*p->uri = '\0';
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p->uri++;
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}
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return 1;
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}
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/* don't even bother */
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static int
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parse_fragment(struct parser *p)
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{
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p->parsed->fragment = p->uri;
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return 1;
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}
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/* XXX: is it too broad? */
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/* *(pchar / "/") */
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static int
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parse_path(struct parser *p)
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{
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char c;
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p->parsed->path = p->uri;
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if (*p->uri == '\0') {
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p->parsed->query = p->parsed->fragment = p->uri;
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return 1;
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}
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while (unreserved(*p->uri)
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|| sub_delimiters(*p->uri)
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|| *p->uri == '/'
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|| parse_pct_encoded(p)
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|| valid_multibyte_utf8(p))
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p->uri++;
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if (p->err != NULL)
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return 0;
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if (*p->uri != '\0' && *p->uri != '?' && *p->uri != '#') {
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p->err = "illegal character in path";
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return 0;
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}
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if (*p->uri != '\0') {
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c = *p->uri;
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*p->uri = '\0';
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p->uri++;
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if (c == '#') {
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if (!parse_fragment(p))
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return 0;
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} else
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if (!parse_query(p) || !parse_fragment(p))
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return 0;
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}
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if (!path_clean(p->parsed->path)) {
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p->err = "illegal path";
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return 0;
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}
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return 1;
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}
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int
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parse_uri(char *uri, struct uri *ret, const char **err_ret)
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{
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char *end;
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struct parser p = {uri, ret, NULL};
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bzero(ret, sizeof(*ret));
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/* initialize optional stuff to the empty string */
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end = uri + strlen(uri);
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p.parsed->port = end;
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p.parsed->path = end;
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p.parsed->query = end;
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p.parsed->fragment = end;
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if (!parse_scheme(&p) || !parse_authority(&p) || !parse_path(&p)) {
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*err_ret = p.err;
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return 0;
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}
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*err_ret = NULL;
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return 1;
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}
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int
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trim_req_uri(char *uri)
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{
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char *i;
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if ((i = strstr(uri, "\r\n")) == NULL)
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return 0;
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*i = '\0';
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return 1;
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}
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