blaze822: iterate over headers

blaze822.c

@@ -559,3 +559,20 @@ blaze822_bodylen(struct message *mesg)
 		return 0;
 	return mesg->bodyend - mesg->body;
 }
+
+char *
+blaze822_next_header(struct message *mesg, char *prev)
+{
+	if (!prev) {
+		prev = mesg->msg;
+	} else {
+		if (prev >= mesg->end)
+			return 0;
+		prev = prev + strlen(prev);
+	}
+	while (prev < mesg->end && *prev == 0)
+		prev++;
+	if (prev >= mesg->end)
+		return 0;
+	return prev;
+}

blaze822.h

@@ -13,6 +13,8 @@ struct message *blaze822_mem(char *buf, size_t len);  // header + body
 char *blaze822_hdr_(struct message *mesg, const char *hdr, size_t len);
 #define blaze822_hdr(mesg, hdr) blaze822_hdr_(mesg, "\0" hdr ":", 2+strlen((hdr)))
 
+char *blaze822_next_header(struct message *mesg, char *prev);
+
 void blaze822_free(struct message *mesg);
 
 time_t blaze822_date(char *);