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Implement MSG_TRUNC faking for UDP, on systems where recvmsg() doesn't set that

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flag for us.  To see if a UDP packet was truncated, look at
done_event->attributes and see if ISC_SOCKEVENTATTR_TRUNC is set.
This commit is contained in:
Michael Graff 1999-09-13 22:00:28 +00:00
parent b18192fd96
commit aca2a14afc
3 changed files with 81 additions and 9 deletions
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3
lib/isc/include/isc/socket.h
View file

@ -78,7 +78,8 @@ ISC_LANG_BEGINDECLS
***/
/*
* Maximum number of buffers in a scatter/gather read/write
* Maximum number of buffers in a scatter/gather read/write. The operating
* system in use must support at least this number (plus one on some.)
*/
#define ISC_SOCKET_MAXSCATTERGATHER 8

9
lib/isc/unix/include/isc/net.h.in
View file

@ -120,6 +120,15 @@
*/
@ISC_NET_MSGHDRFLAVOR@
/*
* If this system does not have MSG_TRUNC (as returned from recvmsg())
* ISC_NET_RECVOVERFLOW will be defined. This will enable the MSG_TRUNC
* faking code in socket.c.
*/
#ifndef MSG_TRUNC
#define ISC_NET_RECVOVERFLOW
#endif
/***
*** Functions.
***/

78
lib/isc/unix/socket.c
View file

@ -146,6 +146,9 @@ struct isc_socket {
connected : 1,
connecting : 1; /* connect pending */
#ifdef ISC_NET_RECVOVERFLOW
unsigned char overflow; /* used for MSG_TRUNC fake */
#endif
#ifdef notyet
unsigned char cmsg[1024]; /* XXX size? */
#endif
@ -175,6 +178,16 @@ struct isc_socketmgr {
#define MANAGED 1
#define CLOSE_PENDING 2
/*
* send() and recv() iovec counts
*/
#define MAXSCATTERGATHER_SEND (ISC_SOCKET_MAXSCATTERGATHER)
#ifdef ISC_NET_RECVOVERFLOW
# define MAXSCATTERGATHER_RECV (ISC_SOCKET_MAXSCATTERGATHER + 1)
#else
# define MAXSCATTERGATHER_RECV (ISC_SOCKET_MAXSCATTERGATHER)
#endif
static void send_recvdone_event(isc_socket_t *, isc_socketevent_t **,
isc_result_t);
static void send_senddone_event(isc_socket_t *, isc_socketevent_t **,
@ -420,7 +433,11 @@ build_msghdr_recv(isc_socket_t *sock, isc_socketevent_t *dev,
memset(&dev->address, 0, sizeof(dev->address));
msg->msg_name = (void *)&dev->address.type.sa;
msg->msg_namelen = sizeof(dev->address.type.sa);
} else {
#ifdef ISC_NET_RECVOVERFLOW
/* If needed, steal one iovec for overflow detection. */
maxiov--;
#endif
} else { /* TCP */
msg->msg_name = NULL;
msg->msg_namelen = 0;
dev->address = sock->address;
@ -436,8 +453,7 @@ build_msghdr_recv(isc_socket_t *sock, isc_socketevent_t *dev,
read_count = dev->region.length - dev->n;
iov[0].iov_base = (void *)(dev->region.base + dev->n);
iov[0].iov_len = read_count;
msg->msg_iov = iov;
msg->msg_iovlen = 1;
iovcount = 1;
goto config;
}
@ -468,10 +484,24 @@ build_msghdr_recv(isc_socket_t *sock, isc_socketevent_t *dev,
buffer = ISC_LIST_NEXT(buffer, link);
}
config:
/*
* If needed, set up to receive that one extra byte. Note that
* we know there is at least one iov left, since we stole it
* at the top of this function.
*/
#ifdef ISC_NET_RECVOVERFLOW
if (sock->type == isc_sockettype_udp) {
iov[iovcount].iov_base = (void *)(&sock->overflow);
iov[iovcount].iov_len = 1;
iovcount++;
}
#endif
msg->msg_iov = iov;
msg->msg_iovlen = iovcount;
config:
#ifdef ISC_NET_BSD44MSGHDR
msg->msg_control = NULL;
msg->msg_controllen = 0;
@ -524,6 +554,22 @@ allocate_socketevent(isc_socket_t *sock, isc_eventtype_t eventtype,
return (ev);
}
#if defined(ISC_SOCKET_DEBUG)
static void
dump_msg(struct msghdr *msg)
{
unsigned int i;
printf("MSGHDR %p\n", msg);
printf("\tname %p, namelen %d\n", msg->msg_name, msg->msg_namelen);
printf("\tiov %p, iovlen %d\n", msg->msg_iov, msg->msg_iovlen);
for (i = 0 ; i < msg->msg_iovlen ; i++)
printf("\t\t%d\tbase %p, len %d\n", i,
msg->msg_iov[i].iov_base,
msg->msg_iov[i].iov_len);
}
#endif
#define DOIO_SUCCESS 0 /* i/o ok, event sent */
#define DOIO_SOFT 1 /* i/o ok, soft error, no event sent */
#define DOIO_HARD 2 /* i/o error, event sent */
@ -534,14 +580,18 @@ static int
doio_recv(isc_socket_t *sock, isc_socketevent_t *dev)
{
int cc;
struct iovec iov[ISC_SOCKET_MAXSCATTERGATHER];
struct iovec iov[MAXSCATTERGATHER_RECV];
size_t read_count;
size_t actual_count;
struct msghdr msghdr;
isc_buffer_t *buffer;
build_msghdr_recv(sock, dev, &msghdr, iov,
ISC_SOCKET_MAXSCATTERGATHER, &read_count);
MAXSCATTERGATHER_RECV, &read_count);
#if defined(ISC_SOCKET_DEBUG)
dump_msg(&msghdr);
#endif
cc = recvmsg(sock->fd, &msghdr, 0);
if (sock->type == isc_sockettype_udp)
@ -595,6 +645,18 @@ doio_recv(isc_socket_t *sock, isc_socketevent_t *dev)
return (DOIO_EOF);
}
/*
* Overflow bit detection. If we received MORE bytes than we should,
* this indicates an overflow situation. Set the flag in the
* dev entry and adjust how much we read by one.
*/
#ifdef ISC_NET_RECVOVERFLOW
if ((sock->type == isc_sockettype_udp) && ((size_t)cc > read_count)) {
dev->attributes |= ISC_SOCKEVENTATTR_TRUNC;
cc--;
}
#endif
/*
* If there are control messages attached, run through them and pull
* out the interesting bits.
@ -646,12 +708,12 @@ static int
doio_send(isc_socket_t *sock, isc_socketevent_t *dev)
{
int cc;
struct iovec iov[ISC_SOCKET_MAXSCATTERGATHER];
struct iovec iov[MAXSCATTERGATHER_SEND];
size_t write_count;
struct msghdr msghdr;
build_msghdr_send(sock, dev, &msghdr, iov,
ISC_SOCKET_MAXSCATTERGATHER, &write_count);
MAXSCATTERGATHER_SEND, &write_count);
cc = sendmsg(sock->fd, &msghdr, 0);