From: Timo Sirainen <timo.sirainen@dovecot.fi>
Date: Wed, 19 Jul 2017 13:49:18 +0000 (+0300)
Subject: lib-mail: Make sure mail_user_hash() won't return 0 as the hash.
X-Git-Tag: 2.2.33.rc1~99
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=b1f56afa6d111233218f5e21958d8be290aa2a6e;p=thirdparty%2Fdovecot%2Fcore.git

lib-mail: Make sure mail_user_hash() won't return 0 as the hash.

It doesn't seem to actually happen, but this makes sure of it.
---

diff --git a/src/lib-mail/mail-user-hash.c b/src/lib-mail/mail-user-hash.c
index 3dc1ff8bbe..d8f1f50d44 100644
--- a/src/lib-mail/mail-user-hash.c
+++ b/src/lib-mail/mail-user-hash.c
@@ -42,6 +42,12 @@ unsigned int mail_user_hash(const char *username, const char *format)
 	} T_END;
 	for (i = 0; i < sizeof(hash); i++)
 		hash = (hash << CHAR_BIT) | md5[i];
+	if (hash == 0) {
+		/* Make sure we don't return the hash as 0, since it's often
+		   treated in a special way that won't work well. For example
+		   trying to insert it into a hash table will assert-crash. */
+		hash = 1;
+	}
 	return hash;
 }
 
diff --git a/src/lib-mail/mail-user-hash.h b/src/lib-mail/mail-user-hash.h
index 3287dfcd05..76fd0ab1ac 100644
--- a/src/lib-mail/mail-user-hash.h
+++ b/src/lib-mail/mail-user-hash.h
@@ -2,7 +2,7 @@
 #define MAIL_USER_HASH
 
 /* Return a hash for username, based on given format. The format can use
-   %n, %d and %u variables. */
+   %n, %d and %u variables. The returned hash is never 0. */
 unsigned int mail_user_hash(const char *username, const char *format);
 
 #endif