From 63d7365ae6d1be6facaabad6ecc80cf6650f5d6d Mon Sep 17 00:00:00 2001
From: Ben Harris <bjh21@bjh21.me.uk>
Date: Sun, 17 May 2015 23:14:57 +0100
Subject: [PATCH] Gratuitous simplification of commasep_string functions.

in_commasep_string() is now implemented in terms of
first_in_commasep_string(), memchr(), and tail recursion.
---
 ssh.c | 60 ++++++++++++++++++++++++-----------------------------------
 1 file changed, 24 insertions(+), 36 deletions(-)

diff --git a/ssh.c b/ssh.c
index e6acec62..47f904eb 100644
--- a/ssh.c
+++ b/ssh.c
@@ -6058,39 +6058,7 @@ static void ssh1_protocol(Ssh ssh, const void *vin, int inlen,
 }
 
 /*
- * Utility routine for decoding comma-separated strings in KEXINIT.
- */
-static int in_commasep_string(char const *needle, char const *haystack,
-			      int haylen)
-{
-    int needlen;
-    if (!needle || !haystack)	       /* protect against null pointers */
-	return 0;
-    needlen = strlen(needle);
-    while (1) {
-	/*
-	 * Is it at the start of the string?
-	 */
-	if (haylen >= needlen &&       /* haystack is long enough */
-	    !memcmp(needle, haystack, needlen) &&	/* initial match */
-	    (haylen == needlen || haystack[needlen] == ',')
-	    /* either , or EOS follows */
-	    )
-	    return 1;
-	/*
-	 * If not, search for the next comma and resume after that.
-	 * If no comma found, terminate.
-	 */
-	while (haylen > 0 && *haystack != ',')
-	    haylen--, haystack++;
-	if (haylen == 0)
-	    return 0;
-	haylen--, haystack++;	       /* skip over comma itself */
-    }
-}
-
-/*
- * Similar routine for checking whether we have the first string in a list.
+ * Utility routines for decoding comma-separated strings in KEXINIT.
  */
 static int first_in_commasep_string(char const *needle, char const *haystack,
 				    int haylen)
@@ -6099,9 +6067,7 @@ static int first_in_commasep_string(char const *needle, char const *haystack,
     if (!needle || !haystack)	       /* protect against null pointers */
 	return 0;
     needlen = strlen(needle);
-    /*
-     * Is it at the start of the string?
-     */
+
     if (haylen >= needlen &&       /* haystack is long enough */
 	!memcmp(needle, haystack, needlen) &&	/* initial match */
 	(haylen == needlen || haystack[needlen] == ',')
@@ -6111,6 +6077,28 @@ static int first_in_commasep_string(char const *needle, char const *haystack,
     return 0;
 }
 
+static int in_commasep_string(char const *needle, char const *haystack,
+			      int haylen)
+{
+    char *p;
+
+    if (!needle || !haystack)	       /* protect against null pointers */
+	return 0;
+    /*
+     * Is it at the start of the string?
+     */
+    if (first_in_commasep_string(needle, haystack, haylen))
+	return 1;
+    /*
+     * If not, search for the next comma and resume after that.
+     * If no comma found, terminate.
+     */
+    p = memchr(haystack, ',', haylen);
+    if (!p) return 0;
+    /* + 1 to skip over comma */
+    return in_commasep_string(needle, p + 1, haylen - (p + 1 - haystack));
+}
+
 /*
  * Add a value to the comma-separated string at the end of the packet.
  * If the value is already in the string, don't bother adding it again.