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- #!/bin/bash
- # Reads HTML from stdin, extracts links and page requisites with simple string splitting and regexes.
- # Usage cannot be recommended against enough.
- # Produces lines of 'TAG URL', e.g. 'a https://example.org/'.
- {
- # Reformat so each line is one tag
- # Yes, this may break attribute values if they contain CR, LF, or <, but that's rare enough.
- tr '\r\n' ' ' | tr '<' '\n' |
-
- # Extract tags of interest
- grep -i '^\(a\|base\|img\|link\|script\)\s' |
-
- # Fix scripty backslash nonsense
- perl -pe 's,\\,,g' |
-
- # Split img tags with src and srcset
- perl -pe "s,^img(?=\s(?:(?:[^>'\"]|\"[^\"]*\"|'[^']*')*\s)?src\s*=\s*([^>'\"\s]*|\"[^\"]*\"|'[^']*')(?:\s|>))\s(?:(?:[^>'\"]|\"[^\"]*\"|'[^']*')*\s)?srcset\s*=\s*([^>'\"\s]*|\"[^\"]*\"|'[^']*')(\s|>).*,img src=\1\nimg srcset=\2,i" |
-
- # Extract interesting tags/attributes
- perl -pe "s,^(a|base)\s(?:(?:[^>'\"]|\"[^\"]*\"|'[^']*')*\s)?href\s*=\s*([^>'\"\s]*|\"[^\"]*\"|'[^']*')(\$|\s|>).*,+\1 \2,i;
- s,^(img|script)\s(?:(?:[^>'\"]|\"[^\"]*\"|'[^']*')*\s)?src\s*=\s*([^>'\"\s]*|\"[^\"]*\"|'[^']*')(\$|\s|>).*,+\1 \2,i;
- s,^(link)\s(?=(?:(?:[^>'\"]|\"[^\"]*\"|'[^']*')*\s)?rel\s*=\s*(?:stylesheet|\"(?:[^\"]*\s)?stylesheet(?:\s[^\"]*)?\"|'(?:[^']*\s)?stylesheet(?:\s[^']*)?')(?:\$|\s|>))(?:(?:[^>'\"]|\"[^\"]*\"|'[^']*')*\s)?href\s*=\s*([^>'\"\s]*|\"[^\"]*\"|'[^']*')(\$|\s|>).*,+\1 \2,i;
- s,^(img)\s(?:(?:[^>'\"]|\"[^\"]*\"|'[^']*')*\s)?(srcset)\s*=\s*([^>'\"\s]*|\"[^\"]*\"|'[^']*')(\$|\s|>).*,+\1\2 \3,i;
- # Ensure that there's a LF at the end of each line since \s might match it.
- s,\s*$,\n,;
- " |
-
- # Filter out unprocessed lines
- grep '^+' | sed 's,^+,,' |
-
- # Remove quotes from attribute values
- perl -pe "s,^([a-zA-Z]+) (['\"])(.*)\2$,\1 \3," |
-
- # Filter out lines without an attribute value
- grep -Pv '^[a-zA-Z]+ $' |
-
- # img srcset splitting
- python3 -c 'import re, sys'$'\n''for l in map(str.strip, sys.stdin):'$'\n'' try:'$'\n'' tag, value = l.split(" ", 1)'$'\n'' tag = tag.lower()'$'\n'' if tag != "imgsrcset":'$'\n'' print(l); continue'$'\n'' for url in re.split(r"\s+\d+[wx]\s*(?:,\s*|$)|,\s+", value.strip()):'$'\n'' if url: print(f"img {url}")'$'\n'' except BrokenPipeError: break' |
-
- # Decode HTML references
- python3 -c 'import html, sys'$'\n''for l in sys.stdin:'$'\n'' try: print(html.unescape(l.strip()))'$'\n'' except BrokenPipeError: break' |
-
- # Combine base and values to get absolute URLs
- # If multiple base tags are present, they all get respected. This violates the HTML specs.
- python3 -c 'import sys, urllib.parse; base = None'$'\n''for l in map(str.strip, sys.stdin):'$'\n'' tag, value = l.split(" ", 1)'$'\n'' tag = tag.lower()'$'\n'' if base:'$'\n'' value = urllib.parse.urljoin(base, value)'$'\n'' if tag == "base":'$'\n'' base = value'$'\n'' continue'$'\n'' try: print(f"{tag} {value}")'$'\n'' except BrokenPipeError: break'
- }
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