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Clarified packet ownership transfer between a few functions.

Browse Source 
Added a large number of missing calls to free_pkb().  In the case of UDP,
no received packets were ever freed, which lead to memory exhaustion
remarkably quickly once pxelinux started up.

In general, any function with _rx() in its name which accepts a pk_buff
*must* either call free_pkb() or pass the pkb to another _rx() function
(e.g. the next layer up the stack).  Since the UDP (and TCP) layers don't
pass packet buffers up to the higher-layer protocols (the
"applications"), they must free the packet buffer after calling the
application's newdata() method.
This commit is contained in:
Michael Brown
2006-08-09 01:24:32 +00:00
parent fd07f56f0d
commit a3d508b648
6 changed files with 63 additions and 31 deletions
Download Patch File Download Diff File Expand all files Collapse all files

53
src/net/udp.c
View File

@@ -93,6 +93,8 @@ void udp_close ( struct udp_connection *conn ) {
* callback. The callback may use the buffer space
*/
int udp_senddata ( struct udp_connection *conn ) {
int rc;
conn->tx_pkb = alloc_pkb ( UDP_MAX_TXPKB );
if ( conn->tx_pkb == NULL ) {
DBG ( "UDP %p cannot allocate packet buffer of length %d\n",
@@ -100,8 +102,11 @@ int udp_senddata ( struct udp_connection *conn ) {
return -ENOMEM;
}
pkb_reserve ( conn->tx_pkb, UDP_MAX_HLEN );
return conn->udp_op->senddata ( conn, conn->tx_pkb->data,
pkb_available ( conn->tx_pkb ) );
rc = conn->udp_op->senddata ( conn, conn->tx_pkb->data,
pkb_available ( conn->tx_pkb ) );
if ( conn->tx_pkb )
free_pkb ( conn->tx_pkb );
return rc;
}
/**
@@ -122,13 +127,20 @@ int udp_senddata ( struct udp_connection *conn ) {
int udp_sendto ( struct udp_connection *conn, struct sockaddr_tcpip *peer,
const void *data, size_t len ) {
struct udp_header *udphdr;
struct pk_buff *pkb;
/* Take ownership of packet buffer back from the
* udp_connection structure.
*/
pkb = conn->tx_pkb;
conn->tx_pkb = NULL;
/* Avoid overflowing TX buffer */
if ( len > pkb_available ( conn->tx_pkb ) )
len = pkb_available ( conn->tx_pkb );
if ( len > pkb_available ( pkb ) )
len = pkb_available ( pkb );
/* Copy payload */
memmove ( pkb_put ( conn->tx_pkb, len ), data, len );
memmove ( pkb_put ( pkb, len ), data, len );
/*
* Add the UDP header
@@ -136,22 +148,22 @@ int udp_sendto ( struct udp_connection *conn, struct sockaddr_tcpip *peer,
* Covert all 16- and 32- bit integers into network btye order before
* sending it over the network
*/
udphdr = pkb_push ( conn->tx_pkb, sizeof ( *udphdr ) );
udphdr = pkb_push ( pkb, sizeof ( *udphdr ) );
udphdr->dest_port = peer->st_port;
udphdr->source_port = conn->local_port;
udphdr->len = htons ( pkb_len ( conn->tx_pkb ) );
udphdr->len = htons ( pkb_len ( pkb ) );
udphdr->chksum = 0;
udphdr->chksum = tcpip_chksum ( udphdr, sizeof ( *udphdr ) + len );
/* Dump debugging information */
DBG ( "UDP %p transmitting %p+%#zx len %#x src %d dest %d "
"chksum %#04x\n", conn, conn->tx_pkb->data,
pkb_len ( conn->tx_pkb ), ntohs ( udphdr->len ),
"chksum %#04x\n", conn, pkb->data,
pkb_len ( pkb ), ntohs ( udphdr->len ),
ntohs ( udphdr->source_port ), ntohs ( udphdr->dest_port ),
ntohs ( udphdr->chksum ) );
/* Send it to the next layer for processing */
return tcpip_tx ( conn->tx_pkb, &udp_protocol, peer );
return tcpip_tx ( pkb, &udp_protocol, peer );
}
/**
@@ -186,12 +198,14 @@ static int udp_rx ( struct pk_buff *pkb, struct sockaddr_tcpip *st_src,
struct udp_connection *conn;
unsigned int ulen;
uint16_t chksum;
int rc;
/* Sanity check */
if ( pkb_len ( pkb ) < sizeof ( *udphdr ) ) {
DBG ( "UDP received underlength packet %p+%#zx\n",
pkb->data, pkb_len ( pkb ) );
return -EINVAL;
rc = -EINVAL;
goto done;
}
/* Dump debugging information */
@@ -205,7 +219,8 @@ static int udp_rx ( struct pk_buff *pkb, struct sockaddr_tcpip *st_src,
if ( ulen > pkb_len ( pkb ) ) {
DBG ( "UDP received truncated packet %p+%#zx\n",
pkb->data, pkb_len ( pkb ) );
return -EINVAL;
rc = -EINVAL;
goto done;
}
pkb_unput ( pkb, ( pkb_len ( pkb ) - ulen ) );
@@ -215,7 +230,8 @@ static int udp_rx ( struct pk_buff *pkb, struct sockaddr_tcpip *st_src,
chksum = tcpip_chksum ( pkb->data, pkb_len ( pkb ) );
if ( chksum != 0xffff ) {
DBG ( "Bad checksum %#x\n", chksum );
return -EINVAL;
rc = -EINVAL;
goto done;
}
#endif
@@ -237,13 +253,18 @@ static int udp_rx ( struct pk_buff *pkb, struct sockaddr_tcpip *st_src,
DBG ( "UDP delivering to %p\n", conn );
/* Call the application's callback */
return conn->udp_op->newdata ( conn, pkb->data, pkb_len( pkb ),
st_src, st_dest );
rc = conn->udp_op->newdata ( conn, pkb->data, pkb_len( pkb ),
st_src, st_dest );
goto done;
}
DBG ( "No UDP connection listening on port %d\n",
ntohs ( udphdr->dest_port ) );
return 0;
rc = 0;
done:
free_pkb ( pkb );
return rc;
}
struct tcpip_protocol udp_protocol = {