140 lines
3.7 KiB
Objective-C
140 lines
3.7 KiB
Objective-C
//
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// NSData+RSParser.m
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// RSParser
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//
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// Created by Brent Simmons on 6/24/17.
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// Copyright © 2017 Ranchero Software, LLC. All rights reserved.
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//
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#import "NSData+RSParser.h"
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/* TODO: find real-world cases where the isProbably* cases fail when they should succeed, and add them to tests.*/
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static BOOL bytesAreProbablyHTML(const char *bytes, NSUInteger numberOfBytes);
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static BOOL bytesAreProbablyXML(const char *bytes, NSUInteger numberOfBytes);
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static BOOL bytesStartWithStringIgnoringWhitespace(const char *string, const char *bytes, NSUInteger numberOfBytes);
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static BOOL didFindString(const char *string, const char *bytes, NSUInteger numberOfBytes);
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static BOOL bytesStartWithRSS(const char *bytes, NSUInteger numberOfBytes);
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static BOOL bytesStartWithRDF(const char *bytes, NSUInteger numberOfBytes);
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static BOOL bytesStartWithAtom(const char *bytes, NSUInteger numberOfBytes);
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@implementation NSData (RSParser)
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- (BOOL)isProbablyHTML {
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return bytesAreProbablyHTML(self.bytes, self.length);
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}
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- (BOOL)isProbablyXML {
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return bytesAreProbablyXML(self.bytes, self.length);
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}
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- (BOOL)isProbablyJSON {
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return bytesStartWithStringIgnoringWhitespace("{", self.bytes, self.length);
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}
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- (BOOL)isProbablyJSONFeed {
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if (![self isProbablyJSON]) {
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return NO;
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}
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return didFindString("://jsonfeed.org/version/", self.bytes, self.length) || didFindString(":\\/\\/jsonfeed.org\\/version\\/", self.bytes, self.length);
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}
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- (BOOL)isProbablyRSSInJSON {
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if (![self isProbablyJSON]) {
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return NO;
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}
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const char *bytes = self.bytes;
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NSUInteger length = self.length;
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return didFindString("rss", bytes, length) && didFindString("channel", bytes, length) && didFindString("item", bytes, length);
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}
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- (BOOL)isProbablyRSS {
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if (didFindString("<rss", self.bytes, self.length) || didFindString("<rdf:RDF", self.bytes, self.length)) {
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return YES;
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}
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// At this writing (7 Dec. 2017), https://www.natashatherobot.com/feed/ is missing an opening <rss> tag, but it should be parsed anyway. It does have some other distinct RSS markers we can find.
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return (didFindString("<channel>", self.bytes, self.length) && didFindString("<pubDate>", self.bytes, self.length));
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}
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- (BOOL)isProbablyAtom {
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return didFindString("<feed", self.bytes, self.length);
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}
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@end
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static BOOL didFindString(const char *string, const char *bytes, NSUInteger numberOfBytes) {
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char *foundString = strnstr(bytes, string, numberOfBytes);
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return foundString != NULL;
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}
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static BOOL bytesStartWithStringIgnoringWhitespace(const char *string, const char *bytes, NSUInteger numberOfBytes) {
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NSUInteger i = 0;
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for (i = 0; i < numberOfBytes; i++) {
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const char ch = bytes[i];
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if (ch == ' ' || ch == '\r' || ch == '\n' || ch == '\t') {
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continue;
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}
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if (ch == string[0]) {
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return strnstr(bytes, string, numberOfBytes) == bytes + i;
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}
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// Allow for a BOM of up to four bytes. ASSUMPTION: BOM will only be at the start of the data.
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if (i < 4) continue;
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break;
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}
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return NO;
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}
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static BOOL bytesAreProbablyHTML(const char *bytes, NSUInteger numberOfBytes) {
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if (didFindString("<html", bytes, numberOfBytes)) {
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return YES;
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}
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if (didFindString("<HTML", bytes, numberOfBytes)) {
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return YES;
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}
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if (didFindString("<body", bytes, numberOfBytes)) {
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return YES;
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}
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if (didFindString("<meta", bytes, numberOfBytes)) {
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return YES;
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}
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if (didFindString("<", bytes, numberOfBytes)) {
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if (didFindString("doctype html", bytes, numberOfBytes)) {
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return YES;
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}
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if (didFindString("DOCTYPE html", bytes, numberOfBytes)) {
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return YES;
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}
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if (didFindString("DOCTYPE HTML", bytes, numberOfBytes)) {
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return YES;
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}
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}
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return NO;
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}
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static BOOL bytesAreProbablyXML(const char *bytes, NSUInteger numberOfBytes) {
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return bytesStartWithStringIgnoringWhitespace("<?xml", bytes, numberOfBytes);
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}
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