commit 113583661d4602da401c981ef2cdd2d4173140d5
parent a530a7d26665b113eb2d8fbdc887321dab1a2f75
Author: sin <sin@2f30.org>
Date: Tue, 12 Apr 2016 15:17:58 +0100
some comments for netpkt.c
Diffstat:
| M | netpkt.c | | | 32 | ++++++++++++++++++++++++++++---- |
1 file changed, 28 insertions(+), 4 deletions(-)
diff --git a/netpkt.c b/netpkt.c
@@ -9,24 +9,39 @@
#include "stun.h"
+/* the various state the input handler can be in */
enum {
STATEINITIAL,
STATENONCE,
STATEHDR,
STATEPAYLOAD,
STATETAG,
- STATEOPEN,
+ STATEDECRYPT,
STATEDISCARD
};
+/* output buffer for writing data to the network */
static unsigned char *wbuf;
+/* input buffer for reading data from the network */
static unsigned char *rbuf;
-static size_t rbuftotal, rbufrem;
+
+/* total number of bytes read into input buffer */
+static size_t rbuftotal
+/* number of bytes remaining to read into buffer for current state */
+static size_t rbufrem;
+
+/* maximum input/output buffer size */
static size_t maxbuflen;
+
+/* nonce size in bytes */
static size_t noncelen;
+/* tag size in bytes */
static size_t taglen;
+
+/* state tracking for input handling */
static int state;
+/* create a packet and write it out to the network in one go */
int
netwrite(int fd, unsigned char *pt, size_t ptlen, size_t *outlen)
{
@@ -44,6 +59,7 @@ netwrite(int fd, unsigned char *pt, size_t ptlen, size_t *outlen)
}
*outlen = ptlen;
+ /* spin until all data is written */
while (buflen > 0) {
n = write(fd, p + total, buflen);
if (n == 0) {
@@ -60,6 +76,10 @@ netwrite(int fd, unsigned char *pt, size_t ptlen, size_t *outlen)
return PKTCOMPLETE;
}
+/*
+ * Since stun is using non-blocking sockets it needs to handle
+ * partial reads. A state machine is devised for this purpose.
+ */
int
netread(int fd, unsigned char *pt, size_t ptlen, size_t *outlen)
{
@@ -121,9 +141,9 @@ netread(int fd, unsigned char *pt, size_t ptlen, size_t *outlen)
rbufrem -= n;
}
if (rbufrem == 0)
- state = STATEOPEN;
+ state = STATEDECRYPT;
break;
- case STATEOPEN:
+ case STATEDECRYPT:
state = STATEINITIAL;
if (!cryptoopen(pt, outlen, ptlen, rbuf, noncelen,
&rbuf[noncelen + HDRLEN],
@@ -151,6 +171,10 @@ out:
return PKTFAILED;
}
+/*
+ * reset state machine, required when a fatal error occurs or when
+ * a client disconnects
+ */
void
netreset(void)
{
