lib: add _notmuch_message_id_parse_strict

The idea is that if a message-id parses with this function, the MUA
generating it was probably sane, and in particular it's probably safe
to use the result as a parent from In-Reply-to.

2 files changed, 44 insertions, 0 deletions

diff --git a/lib/message-id.c b/lib/message-id.c
index d7541d50..e71ce9f4 100644
--- a/lib/message-id.c
+++ b/lib/message-id.c
@@ -1,4 +1,5 @@
 #include "notmuch-private.h"
+#include "string-util.h"
 
 /* Advance 'str' past any whitespace or RFC 822 comments. A comment is
  * a (potentially nested) parenthesized sequence with '\' used to
@@ -94,3 +95,32 @@ _notmuch_message_id_parse (void *ctx, const char *message_id, const char **next)
 
     return result;
 }
+
+char *
+_notmuch_message_id_parse_strict (void *ctx, const char *message_id)
+{
+    const char *s, *end;
+
+    if (message_id == NULL || *message_id == '\0')
+	return NULL;
+
+    s = skip_space (message_id);
+    if (*s == '<')
+	s++;
+    else
+	return NULL;
+
+    for (end = s; *end && *end != '>'; end++)
+	if (isspace (*end))
+	    return NULL;
+
+    if (*end != '>')
+	return NULL;
+    else {
+	const char *last = skip_space (end + 1);
+	if (*last != '\0')
+	    return NULL;
+    }
+
+    return talloc_strndup (ctx, s, end - s);
+}
diff --git a/lib/notmuch-private.h b/lib/notmuch-private.h
index 9eca0789..df32d39c 100644
--- a/lib/notmuch-private.h
+++ b/lib/notmuch-private.h
@@ -533,6 +533,20 @@ _notmuch_query_count_documents (notmuch_query_t *query,
 char *
 _notmuch_message_id_parse (void *ctx, const char *message_id, const char **next);
 
+/* Parse a message-id, discarding leading and trailing whitespace, and
+ * '<' and '>' delimiters.
+ *
+ * Apply a probably-stricter-than RFC definition of what is allowed in
+ * a message-id. In particular, forbid whitespace.
+ *
+ * Returns a newly talloc'ed string belonging to 'ctx'.
+ *
+ * Returns NULL if there is any error parsing the message-id.
+ */
+
+char *
+_notmuch_message_id_parse_strict (void *ctx, const char *message_id);
+
 
 /* message.cc */