From: Willy Tarreau <w@1wt.eu>
Date: Wed, 2 Sep 2020 05:08:47 +0000 (+0200)
Subject: CLEANUP: http: silence a cppcheck warning in get_http_auth()
X-Git-Tag: v2.3-dev4~36
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=17254939c50707f06f2c248337990fc8e8d4d75b;p=thirdparty%2Fhaproxy.git

CLEANUP: http: silence a cppcheck warning in get_http_auth()

In issue #777, cppcheck wrongly assumes a useless null pointer check
in the expression below while it's obvious that in a 3G/1G split on
32-bit, len can become positive if p is NULL:

     p = memchr(ctx.value.ptr, ' ', ctx.value.len);
     len = p - ctx.value.ptr;
     if (!p || len <= 0)
           return 0;

In addition, on 64 bits you never know given that len is a 32-bit signed
int thus the sign of the result in case of a null p will always be the
opposite of the 32th bit of ctx.value.ptr. Admittedly the test is ugly.

Tim proposed this fix consisting in checking for p == ctx.value.ptr
instead when checking for first character only, which Ilya confirmed is
enough to shut cppcheck up. No backport is needed.
---

diff --git a/src/http_fetch.c b/src/http_fetch.c
index 460bfbd349..2149b7fa2f 100644
--- a/src/http_fetch.c
+++ b/src/http_fetch.c
@@ -113,10 +113,10 @@ static int get_http_auth(struct sample *smp, struct htx *htx)
 	if (!http_find_header(htx, hdr, &ctx, 0))
 		return 0;
 
-	p   = memchr(ctx.value.ptr, ' ', ctx.value.len);
-	len = p - ctx.value.ptr;
-	if (!p || len <= 0)
+	p = memchr(ctx.value.ptr, ' ', ctx.value.len);
+	if (!p || p == ctx.value.ptr) /* if no space was found or if the space is the first character */
 		return 0;
+	len = p - ctx.value.ptr;
 
 	if (chunk_initlen(&auth_method, ctx.value.ptr, 0, len) != 1)
 		return 0;