[Dovecot] antispam plugin claims "antispam signature not found"

[Johannes Berg]

On Tue, 2008-11-11 at 11:42 +0100, Johannes Berg wrote:

> Not sure, I personally think that moving them silently makes errors
> harder to diagnose. I'll add an option since then you can set this
> option (antispam_missing_signature = [error|move]) to move after you've
> tested and verified that it works just fine.

Try this patch please, I have only compiled it so far. (there might be
rejects in the signature-log.c file unless you update to the current git
tree but you don't care about that)

diff --git a/antispam.7 b/antispam.7
index d07c1d0..e26db69 100644
--- a/antispam.7
+++ b/antispam.7
@@ -108,6 +108,13 @@ plugin {
     # mail signature (used with any backend requiring a signature)
     antispam_signature = X-DSPAM-Signature
 
+    # action to take on mails without signature
+    # (used with any backend requiring a signature)
+    # (we recommend only setting this to 'move' after verifying that the
+    # whole setup is working)
+    # antispam_signature_missing = move # move silently without training
+    antispam_signature_missing = error
+
     # semicolon-separated list of Trash folders (default unset i.e. none)
     # antispam_trash =
     # antispam_trash = trash;Trash;Deleted Items
diff --git a/signature-log.c b/signature-log.c
index ab8cd6d..5b7b306 100644
--- a/signature-log.c
+++ b/signature-log.c
@@ -99,7 +99,12 @@ int backend_handle_mail(struct mailbox_transaction_context *t,
 		return -1;
 	}
 
-	signature = signature_extract(t, mail);
+	ret = signature_extract(t, mail, &signature);
+	if (ret)
+		return ret;
+
+	if (!signature)
+		return 0;
 
 	switch (wanted) {
 	case CLASS_SPAM:
diff --git a/signature.c b/signature.c
index 7f9d83b..7ad29d6 100644
--- a/signature.c
+++ b/signature.c
@@ -5,6 +5,7 @@
 #include "mail-storage-private.h"
 
 const char *signature_hdr = "X-DSPAM-Signature";
+static int signature_nosig_ignore = 0;
 
 void signature_init(void)
 {
@@ -12,6 +13,16 @@ void signature_init(void)
 	if (tmp)
 		signature_hdr = tmp;
 	debug("signature header line is \"%s\"\n", signature_hdr);
+
+	tmp = get_setting("SIGNATURE_MISSING");
+	if (!tmp)
+		tmp = "error";
+	if (strcmp(tmp, "move") == 0) {
+		signature_nosig_ignore = 1;
+		debug("will silently move mails with missing signature\n");
+	} else if (strcmp(tmp, "error") != 0) {
+		debug("invalid signature_missing setting '%s', ignoring\n", tmp);
+	}
 }
 
 int signature_extract_to_list(struct mailbox_transaction_context *t,
@@ -23,10 +34,14 @@ int signature_extract_to_list(struct mailbox_transaction_context *t,
 
 	signatures = get_mail_headers(mail, signature_hdr);
 	if (!signatures || !signatures[0]) {
-		mail_storage_set_error(t->box->storage,
-				       ME(NOTPOSSIBLE)
-				       "antispam signature not found");
-		return -1;
+		if (!signature_nosig_ignore) {
+			mail_storage_set_error(t->box->storage,
+					       ME(NOTPOSSIBLE)
+					       "antispam signature not found");
+			return -1;
+		} else {
+			return 0;
+		}
 	}
 
 	while (signatures[1])
@@ -42,23 +57,30 @@ int signature_extract_to_list(struct mailbox_transaction_context *t,
 	return 0;
 }
 
-const char *signature_extract(struct mailbox_transaction_context *t,
-			      struct mail *mail)
+int signature_extract(struct mailbox_transaction_context *t,
+		      struct mail *mail, const char **signature)
 {
 	const char *const *signatures;
 
 	signatures = get_mail_headers(mail, signature_hdr);
 	if (!signatures || !signatures[0]) {
-		mail_storage_set_error(t->box->storage,
-				       ME(NOTPOSSIBLE)
-				       "antispam signature not found");
-		return NULL;
+		if (!signature_nosig_ignore) {
+			mail_storage_set_error(t->box->storage,
+					       ME(NOTPOSSIBLE)
+					       "antispam signature not found");
+			return -1;
+		} else {
+			*signature = NULL;
+			return 0;
+		}
 	}
 
 	while (signatures[1])
 		signatures++;
 
-	return signatures[0];
+	*signature = signatures[0];
+
+	return 0;
 }
 
 void signature_list_free(struct siglist **list)
diff --git a/signature.h b/signature.h
index e25d1b5..1384924 100644
--- a/signature.h
+++ b/signature.h
@@ -16,8 +16,8 @@ void signature_init(void);
 int signature_extract_to_list(struct mailbox_transaction_context *t,
 			      struct mail *mail, struct siglist **list,
 			      enum classification wanted);
-const char *signature_extract(struct mailbox_transaction_context *t,
-			      struct mail *mail);
+int signature_extract(struct mailbox_transaction_context *t,
+		      struct mail *mail, const char **signature);
 void signature_list_free(struct siglist **list);
 
 extern const char *signature_hdr;