From bcd8d530d10127ce0be796fe7ef42944c47d4485 Mon Sep 17 00:00:00 2001
From: Jo-Philipp Wich <jow@openwrt.org>
Date: Thu, 3 May 2012 17:19:18 +0000
Subject: [PATCH] Fixed: [PATCH 2/3] uhttpd URL-codec enhancements.
My apologies, the 2nd of those patches had a syntax error -- that's what
I get for making a last-minute edit, even to the comments, without
testing! :-p
Here is the corrected patch.
-- David
From d259cff104d2084455476b82e92a3a27524f4263 Mon Sep 17 00:00:00 2001
From: David Favro <openwrt@meta-dynamic.com>
Date: Fri, 27 Apr 2012 14:17:52 -0400
Subject: [PATCH] uhttpd URL-codec enhancements.
* uh_urlencode() and uh_urldecode() now return an error condition for
buffer-overflow and malformed-encoding rather than normal return with corrupt
or truncated data. As HTTP request processing is currently implemented, this
causes a 404 HTTP status returned to the client, while 400 is more
appropriate.
* Exposed urlencode() to Lua.
* Lua's uhttpd.urlencode() and .urldecode() now raise an error condition for
buffer-overflow and malformed-encoding rather than normal return with
incorrect data.
SVN-Revision: 31570
---
package/uhttpd/src/uhttpd-lua.c | 24 +++++++++++++++---
package/uhttpd/src/uhttpd-utils.c | 42 ++++++++++++++++++++-----------
package/uhttpd/src/uhttpd.c | 7 +++---
3 files changed, 52 insertions(+), 21 deletions(-)
diff --git a/package/uhttpd/src/uhttpd-lua.c b/package/uhttpd/src/uhttpd-lua.c
index c2efe33849..a140dc2f2d 100644
--- a/package/uhttpd/src/uhttpd-lua.c
+++ b/package/uhttpd/src/uhttpd-lua.c
@@ -108,19 +108,34 @@ static int uh_lua_sendc(lua_State *L)
return uh_lua_send_common(L, 1);
}
-static int uh_lua_urldecode(lua_State *L)
+static int uh_lua_str2str(lua_State *L, int (*xlate_func) (char *, int, const char *, int))
{
- size_t inlen, outlen;
+ size_t inlen;
+ int outlen;
const char *inbuf;
char outbuf[UH_LIMIT_MSGHEAD];
inbuf = luaL_checklstring(L, 1, &inlen);
- outlen = uh_urldecode(outbuf, sizeof(outbuf), inbuf, inlen);
+ outlen = (* xlate_func)(outbuf, sizeof(outbuf), inbuf, inlen);
+ if( outlen < 0 )
+ luaL_error( L, "%s on URL-encode codec",
+ (outlen==-1) ? "buffer overflow" : "malformed string" );
lua_pushlstring(L, outbuf, outlen);
return 1;
}
+static int uh_lua_urldecode(lua_State *L)
+{
+ return uh_lua_str2str( L, uh_urldecode );
+}
+
+
+static int uh_lua_urlencode(lua_State *L)
+{
+ return uh_lua_str2str( L, uh_urlencode );
+}
+
lua_State * uh_lua_init(const char *handler)
{
@@ -146,6 +161,9 @@ lua_State * uh_lua_init(const char *handler)
lua_pushcfunction(L, uh_lua_urldecode);
lua_setfield(L, -2, "urldecode");
+ lua_pushcfunction(L, uh_lua_urlencode);
+ lua_setfield(L, -2, "urlencode");
+
/* _G.uhttpd = { ... } */
lua_setfield(L, LUA_GLOBALSINDEX, "uhttpd");
diff --git a/package/uhttpd/src/uhttpd-utils.c b/package/uhttpd/src/uhttpd-utils.c
index 1073f3bb34..1dac33db0f 100644
--- a/package/uhttpd/src/uhttpd-utils.c
+++ b/package/uhttpd/src/uhttpd-utils.c
@@ -307,7 +307,7 @@ int uh_http_send(
/* blen is the size of buf; slen is the length of src. The input-string need
** not be, and the output string will not be, null-terminated. Returns the
-** length of the decoded string. */
+** length of the decoded string, -1 on buffer overflow, -2 on malformed string. */
int uh_urldecode(char *buf, int blen, const char *src, int slen)
{
int i;
@@ -329,7 +329,15 @@ int uh_urldecode(char *buf, int blen, const char *src, int slen)
}
else
{
- buf[len++] = '%';
+ /* Encoding error: it's hard to think of a
+ ** scenario in which returning an incorrect
+ ** 'decoding' of the malformed string is
+ ** preferable to signaling an error condition. */
+ #if 0 /* WORSE_IS_BETTER */
+ buf[len++] = '%';
+ #else
+ return -2;
+ #endif
}
}
else
@@ -338,12 +346,12 @@ int uh_urldecode(char *buf, int blen, const char *src, int slen)
}
}
- return len;
+ return (i == slen) ? len : -1;
}
/* blen is the size of buf; slen is the length of src. The input-string need
** not be, and the output string will not be, null-terminated. Returns the
-** length of the encoded string. */
+** length of the encoded string, or -1 on error (buffer overflow) */
int uh_urlencode(char *buf, int blen, const char *src, int slen)
{
int i;
@@ -365,11 +373,12 @@ int uh_urlencode(char *buf, int blen, const char *src, int slen)
}
else
{
+ len = -1;
break;
}
}
- return len;
+ return (i == slen) ? len : -1;
}
int uh_b64decode(char *buf, int blen, const unsigned char *src, int slen)
@@ -495,6 +504,9 @@ static char * canonpath(const char *path, char *path_resolved)
return NULL;
}
+/* Returns NULL on error.
+** NB: improperly encoded URL should give client 400 [Bad Syntax]; returning
+** NULL here causes 404 [Not Found], but that's not too unreasonable. */
struct path_info * uh_path_lookup(struct client *cl, const char *url)
{
static char path_phys[PATH_MAX];
@@ -530,21 +542,21 @@ struct path_info * uh_path_lookup(struct client *cl, const char *url)
/* urldecode component w/o query */
if( pathptr > url )
- uh_urldecode(
- &buffer[strlen(docroot)],
- sizeof(buffer) - strlen(docroot) - 1,
- url, pathptr - url
- );
+ if ( uh_urldecode(
+ &buffer[strlen(docroot)],
+ sizeof(buffer) - strlen(docroot) - 1,
+ url, pathptr - url ) < 0 )
+ return NULL; /* bad URL */
}
/* no query string, decode all of url */
else
{
- uh_urldecode(
- &buffer[strlen(docroot)],
- sizeof(buffer) - strlen(docroot) - 1,
- url, strlen(url)
- );
+ if ( uh_urldecode(
+ &buffer[strlen(docroot)],
+ sizeof(buffer) - strlen(docroot) - 1,
+ url, strlen(url) ) < 0 )
+ return NULL; /* bad URL */
}
/* create canon path */
diff --git a/package/uhttpd/src/uhttpd.c b/package/uhttpd/src/uhttpd.c
index 9b9608628d..5d66e23a50 100644
--- a/package/uhttpd/src/uhttpd.c
+++ b/package/uhttpd/src/uhttpd.c
@@ -948,9 +948,10 @@ int main (int argc, char **argv)
for (opt = 0; optarg[opt]; opt++)
if (optarg[opt] == '+')
optarg[opt] = ' ';
-
- memset(port, 0, strlen(optarg)+1);
- uh_urldecode(port, strlen(optarg), optarg, strlen(optarg));
+ /* opt now contains strlen(optarg) -- no need to re-scan */
+ memset(port, 0, opt+1);
+ if (uh_urldecode(port, opt, optarg, opt) < 0)
+ fprintf( stderr, "uhttpd: invalid encoding\n" );
printf("%s", port);
free(port);
--
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