From a2c6355f9fdede78ce46aeee39ef649637aaadf9 Mon Sep 17 00:00:00 2001 From: Mark Lodato Date: Tue, 9 Feb 2010 10:12:43 -0500 Subject: html: properly percent-escape URLs The only valid characters for a URL are unreserved characters a-zA-Z0-9_-.~ and the reserved characters !*'();:@&=+$,/?%#[] , as per RFC 3986. Everything else must be escaped. Additionally, the # and ? always have special meaning, and the &, =, and + have special meaning in a query string, so they too must be escaped. To make this easier, a table of escapes is now used so that we do not have to call fmt() for each character; if the entry is 0, no escaping is needed. Signed-off-by: Mark Lodato --- html.c | 36 ++++++++++++++++++++++++++++++++---- 1 file changed, 32 insertions(+), 4 deletions(-) (limited to 'html.c') diff --git a/html.c b/html.c index 4033200..337baeb 100644 --- a/html.c +++ b/html.c @@ -13,6 +13,32 @@ #include #include +/* Percent-encoding of each character, except: a-zA-Z0-9!$()*,./:;@- */ +static const char* url_escape_table[256] = { + "%00", "%01", "%02", "%03", "%04", "%05", "%06", "%07", "%08", "%09", + "%0a", "%0b", "%0c", "%0d", "%0e", "%0f", "%10", "%11", "%12", "%13", + "%14", "%15", "%16", "%17", "%18", "%19", "%1a", "%1b", "%1c", "%1d", + "%1e", "%1f", "%20", 0, "%22", "%23", 0, "%25", "%26", "%27", 0, 0, 0, + "%2b", 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, "%3c", "%3d", + "%3e", "%3f", 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, + 0, 0, 0, 0, 0, 0, 0, 0, 0, "%5c", 0, "%5e", 0, "%60", 0, 0, 0, 0, 0, + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, "%7b", + "%7c", "%7d", 0, "%7f", "%80", "%81", "%82", "%83", "%84", "%85", + "%86", "%87", "%88", "%89", "%8a", "%8b", "%8c", "%8d", "%8e", "%8f", + "%90", "%91", "%92", "%93", "%94", "%95", "%96", "%97", "%98", "%99", + "%9a", "%9b", "%9c", "%9d", "%9e", "%9f", "%a0", "%a1", "%a2", "%a3", + "%a4", "%a5", "%a6", "%a7", "%a8", "%a9", "%aa", "%ab", "%ac", "%ad", + "%ae", "%af", "%b0", "%b1", "%b2", "%b3", "%b4", "%b5", "%b6", "%b7", + "%b8", "%b9", "%ba", "%bb", "%bc", "%bd", "%be", "%bf", "%c0", "%c1", + "%c2", "%c3", "%c4", "%c5", "%c6", "%c7", "%c8", "%c9", "%ca", "%cb", + "%cc", "%cd", "%ce", "%cf", "%d0", "%d1", "%d2", "%d3", "%d4", "%d5", + "%d6", "%d7", "%d8", "%d9", "%da", "%db", "%dc", "%dd", "%de", "%df", + "%e0", "%e1", "%e2", "%e3", "%e4", "%e5", "%e6", "%e7", "%e8", "%e9", + "%ea", "%eb", "%ec", "%ed", "%ee", "%ef", "%f0", "%f1", "%f2", "%f3", + "%f4", "%f5", "%f6", "%f7", "%f8", "%f9", "%fa", "%fb", "%fc", "%fd", + "%fe", "%ff" +}; + int htmlfd = STDOUT_FILENO; char *fmt(const char *format, ...) @@ -135,9 +161,10 @@ void html_url_path(const char *txt) const char *t = txt; while(t && *t){ int c = *t; - if (c=='"' || c=='#' || c=='\'' || c=='?') { + const char *e = url_escape_table[c]; + if (e && c!='+' && c!='&' && c!='+') { write(htmlfd, txt, t - txt); - write(htmlfd, fmt("%%%2x", c), 3); + write(htmlfd, e, 3); txt = t+1; } t++; @@ -151,9 +178,10 @@ void html_url_arg(const char *txt) const char *t = txt; while(t && *t){ int c = *t; - if (c=='"' || c=='#' || c=='%' || c=='&' || c=='\'' || c=='+' || c=='?') { + const char *e = url_escape_table[c]; + if (e) { write(htmlfd, txt, t - txt); - write(htmlfd, fmt("%%%2x", c), 3); + write(htmlfd, e, 3); txt = t+1; } t++; -- cgit v1.2.1