Some initial APRS parsing code

git-svn-id: http://repo.ham.fi/svn/aprsc/trunk@7 3ce903b1-3385-4e86-93cd-f9a4a239f7ac

src/incoming.c

@@ -74,6 +74,18 @@ struct pbuf_t *pbuf_get_real(struct pbuf_t **pool, struct pbuf_t **global_pool,
 	/* ok, return the first buffer from the pool */
 	pb = *pool;
 	*pool = pb->next;
+	
+	/* zero some fields */
+	pb->next = NULL;
+	pb->flags = 0;
+	pb->packettype = 0;
+	pb->t = 0;
+	pb->packet_len = 0;
+	pb->srccall_end = NULL;
+	pb->dstcall_end = NULL;
+	pb->info_start = NULL;
+	pb->lat = pb->lng = 0;
+	
 	return pb;
 }
 
@@ -212,12 +224,8 @@ int incoming_handler(struct worker_t *self, struct client_t *c, char *s, int len
 	if (!(pb = pbuf_get(self, len+2)))
 		return 0;
 	
-	/* fill the buffer */
+	/* fill the buffer (it's zeroed by pbuf_get) */
 	pb->t = now;
-	pb->packettype = 0;
-	pb->flags = 0;
-	pb->lat = 0;
-	pb->lng = 0;
 	
 	pb->packet_len = len+2;
 	memcpy(pb->data, s, len);

src/parse_aprs.c

@@ -2,8 +2,89 @@
 #include "parse_aprs.h"
 #include "hlog.h"
 
+int parse_aprs_mice(struct pbuf_t *pb)
+{
+	return 0;
+}
+
+int parse_aprs_compressed(struct pbuf_t *pb, char *body, const char *body_end)
+{
+	return 0;
+}
+
+int parse_aprs_uncompressed(struct pbuf_t *pb, char *body, const char *body_end)
+{
+	return 0;
+}
+
+/*
+ *	Try to parse an APRS packet.
+ *	Returns 1 if position was parsed successfully,
+ *	0 if parsing failed.
+ */
+
 int parse_aprs(struct worker_t *self, struct pbuf_t *pb)
 {
+	char packettype, poschar;
+	int paclen;
+	char *body;
+	char *body_end = pb->data + pb->packet_len - 2;
+	
+	if (!pb->info_start)
+		return 0;
+	
+	/* the following parsing logic has been translated from Ham::APRS::FAP
+	 * Perl module to C
+	 */
+	
+	/* length of the info field: length of the packet - length of header - CRLF */
+	paclen = pb->packet_len - (pb->info_start - pb->data) - 2;
+	/* Check the first character of the packet and determine the packet type */
+	packettype = *pb->info_start;
+	
+	/* failed parsing */
+	fprintf(stderr, "parse_aprs (%d):\n", paclen);
+	fwrite(pb->info_start, paclen, 1, stderr);
+	fprintf(stderr, "\n");
+	
+	if (packettype == 0x27 || packettype == 0x60) {
+		/* could be mic-e, minimum body length 9 chars */
+		if (paclen >= 9)
+			return parse_aprs_mice(pb);
+	} else if (packettype == '!' || packettype == '=' || packettype == '/'
+		|| packettype == '@') {
+		/* body is right after the packet type character */
+		body = pb->info_start + 1;
+		/* check that we won't run over right away */
+		if (body_end - body < 10)
+			return -1;
+		/* Normal or compressed location packet, with or without
+		 * timestamp, with or without messaging capability
+		 *
+		 * ! and / have messaging, / and @ have a prepended timestamp
+		 */
+		if (packettype == '/' || packettype == '@') {
+			/* With a prepended timestamp, jump over it. */
+			body += 7;
+		}
+		poschar = *body;
+		if (poschar == '/' || poschar == '\\' || (poschar >= 0x41 && poschar <= 0x5A)
+		    || (poschar >= 0x61 && poschar <= 0x6A)) { /* [\/\\A-Za-j] */
+		    	/* compressed position packet */
+			if (body_end - body >= 13) {
+				return parse_aprs_compressed(pb, body, body_end);
+			}
+			return 0;
+			
+		} else if (poschar >= 0x30 && poschar <= 0x39) { /* [0-9] */
+			/* normal uncompressed position */
+			if (body_end - body >= 19) {
+				return parse_aprs_uncompressed(pb, body, body_end);
+			}
+			return 0;
+		}
+		
+	}
 	
 	return 0;
 }