Currently, we drop any netlink data beyond our 4096-byte buffer. This
means that we can only parse a limited number of network interfaces.
This change uses recvmsg with MSG_PEEK to determine the size of an
incoming netlink message before doing the actual recvmsg. This way, we
can realloc our buffer to suit.
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
#define HWADDR_SIZE 6
#define PIDFILE_BASE (LOCAL_STATE_DIR "/petitboot/")
#define HWADDR_SIZE 6
#define PIDFILE_BASE (LOCAL_STATE_DIR "/petitboot/")
+#define INITIAL_BUFSIZE 4096
#define for_each_nlmsg(buf, nlmsg, len) \
for (nlmsg = (struct nlmsghdr *)buf; \
#define for_each_nlmsg(buf, nlmsg, len) \
for (nlmsg = (struct nlmsghdr *)buf; \
struct device_handler *handler;
struct waiter *waiter;
int netlink_sd;
struct device_handler *handler;
struct waiter *waiter;
int netlink_sd;
+ void *netlink_buf;
+ unsigned int netlink_buf_size;
bool manual_config;
bool dry_run;
};
bool manual_config;
bool dry_run;
};
+ network->netlink_buf_size = INITIAL_BUFSIZE;
+ network->netlink_buf = talloc_array(network, char,
+ network->netlink_buf_size);
+
{
struct network *network = arg;
struct nlmsghdr *nlmsg;
{
struct network *network = arg;
struct nlmsghdr *nlmsg;
+ struct msghdr msg;
+ struct iovec iov;
- char buf[4096];
- int rc;
+ int rc, flags;
+
+ memset(&msg, 0, sizeof(msg));
+ msg.msg_iov = &iov;
+ msg.msg_iovlen = 1;
+
+ flags = MSG_PEEK;
+
+retry:
+ iov.iov_len = network->netlink_buf_size;
+ iov.iov_base = network->netlink_buf;
+
+ rc = recvmsg(network->netlink_sd, &msg, flags);
- rc = recv(network->netlink_sd, buf, sizeof(buf), 0);
- perror("netlink recv");
+ perror("netlink recv header");
- for_each_nlmsg(buf, nlmsg, len)
+ /* if the netlink message was larger than our buffer, realloc
+ * before reading again */
+ if (len > network->netlink_buf_size || msg.msg_flags & MSG_TRUNC) {
+ network->netlink_buf_size *= 2;
+ network->netlink_buf = talloc_realloc(network,
+ network->netlink_buf,
+ char *,
+ network->netlink_buf_size);
+ goto retry;
+ }
+
+ /* otherwise, we're good to read the entire message without PEEK */
+ if (flags == MSG_PEEK) {
+ flags = 0;
+ goto retry;
+ }
+
+ for_each_nlmsg(network->netlink_buf, nlmsg, len)
network_handle_nlmsg(network, nlmsg);
return 0;
network_handle_nlmsg(network, nlmsg);
return 0;