1 files changed, 48 insertions, 0 deletions
diff --git a/src/lib-mail/mail-user-hash.c b/src/lib-mail/mail-user-hash.c
new file mode 100644
index 0000000..88724a6
--- /dev/null
+++ b/src/lib-mail/mail-user-hash.c
@@ -0,0 +1,48 @@
+/* Copyright (c) 2013-2018 Dovecot authors, see the included COPYING file */
+
+#include "lib.h"
+#include "md5.h"
+#include "str.h"
+#include "var-expand.h"
+#include "mail-user-hash.h"
+
+bool mail_user_hash(const char *username, const char *format,
+		    unsigned int *hash_r, const char **error_r)
+{
+	unsigned char md5[MD5_RESULTLEN];
+	unsigned int i, hash = 0;
+	int ret = 1;
+
+	if (strcmp(format, "%u") == 0) {
+		/* fast path */
+		md5_get_digest(username, strlen(username), md5);
+	} else if (strcmp(format, "%Lu") == 0) {
+		/* almost as fast path */
+		T_BEGIN {
+			md5_get_digest(t_str_lcase(username),
+				       strlen(username), md5);
+		} T_END;
+	} else T_BEGIN {
+		const struct var_expand_table tab[] = {
+			{ 'u', username, "user" },
+			{ 'n', t_strcut(username, '@'), "username" },
+			{ 'd', i_strchr_to_next(username, '@'), "domain" },
+			{ '\0', NULL, NULL }
+		};
+		string_t *str = t_str_new(128);
+
+		ret = var_expand(str, format, tab, error_r);
+		i_assert(ret >= 0);
+		md5_get_digest(str_data(str), str_len(str), md5);
+	} T_END_PASS_STR_IF(ret == 0, error_r);
+	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;
+	}
+	*hash_r = hash;
+	return ret > 0;
+}