Merge branch 'release/0.0.1'

[catta] / src / netlink.c

diff --git a/src/netlink.c b/src/netlink.c
new file mode 100644 (file)
index 0000000..91df672
--- /dev/null
+++ b/src/netlink.c
@@ -0,0 +1,208 @@
+/***
+  This file is part of catta.
+
+  catta is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as
+  published by the Free Software Foundation; either version 2.1 of the
+  License, or (at your option) any later version.
+
+  catta is distributed in the hope that it will be useful, but WITHOUT
+  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+  or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
+  Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with catta; if not, write to the Free Software
+  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+  USA.
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <assert.h>
+
+#include <catta/malloc.h>
+#include "netlink.h"
+#include <catta/log.h>
+
+struct CattaNetlink {
+    int fd;
+    unsigned seq;
+    CattaNetlinkCallback callback;
+    void* userdata;
+    uint8_t* buffer;
+    size_t buffer_length;
+
+    const CattaPoll *poll_api;
+    CattaWatch *watch;
+};
+
+int catta_netlink_work(CattaNetlink *nl, int block) {
+    ssize_t bytes;
+    struct msghdr smsg;
+    struct cmsghdr *cmsg;
+    struct ucred *cred;
+    struct iovec iov;
+    struct nlmsghdr *p;
+    char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
+
+    assert(nl);
+
+    iov.iov_base = nl->buffer;
+    iov.iov_len = nl->buffer_length;
+
+    smsg.msg_name = NULL;
+    smsg.msg_namelen = 0;
+    smsg.msg_iov = &iov;
+    smsg.msg_iovlen = 1;
+    smsg.msg_control = cred_msg;
+    smsg.msg_controllen = sizeof(cred_msg);
+    smsg.msg_flags = (block ? 0 : MSG_DONTWAIT);
+
+    if ((bytes = recvmsg(nl->fd, &smsg, 0)) < 0) {
+        if (errno == EAGAIN || errno == EINTR)
+            return 0;
+
+        catta_log_error(__FILE__": recvmsg() failed: %s", strerror(errno));
+        return -1;
+    }
+
+    cmsg = CMSG_FIRSTHDR(&smsg);
+
+    if (!cmsg || cmsg->cmsg_type != SCM_CREDENTIALS) {
+        catta_log_warn("No sender credentials received, ignoring data.");
+        return -1;
+    }
+
+    cred = (struct ucred*) CMSG_DATA(cmsg);
+
+    if (cred->uid != 0)
+        return -1;
+
+    p = (struct nlmsghdr *) nl->buffer;
+
+    assert(nl->callback);
+
+    for (; bytes > 0; p = NLMSG_NEXT(p, bytes)) {
+        if (!NLMSG_OK(p, (size_t) bytes)) {
+            catta_log_warn(__FILE__": packet truncated");
+            return -1;
+        }
+
+        nl->callback(nl, p, nl->userdata);
+    }
+
+    return 0;
+}
+
+static void socket_event(CattaWatch *w, int fd, CATTA_GCC_UNUSED CattaWatchEvent event, void *userdata) {
+    CattaNetlink *nl = userdata;
+
+    assert(w);
+    assert(nl);
+    assert(fd == nl->fd);
+
+    catta_netlink_work(nl, 0);
+}
+
+CattaNetlink *catta_netlink_new(const CattaPoll *poll_api, uint32_t groups, void (*cb) (CattaNetlink *nl, struct nlmsghdr *n, void* userdata), void* userdata) {
+    int fd = -1;
+    const int on = 1;
+    struct sockaddr_nl addr;
+    CattaNetlink *nl = NULL;
+
+    assert(poll_api);
+    assert(cb);
+
+    if ((fd = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE)) < 0) {
+        catta_log_error(__FILE__": socket(PF_NETLINK): %s", strerror(errno));
+        return NULL;
+    }
+
+    memset(&addr, 0, sizeof(addr));
+    addr.nl_family = AF_NETLINK;
+    addr.nl_groups = groups;
+    addr.nl_pid = 0; // use 0 instead of getpid() to allow multiple instances of catta in one process
+
+    if (bind(fd, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
+        catta_log_error(__FILE__": bind(): %s", strerror(errno));
+        goto fail;
+    }
+
+    if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)) < 0) {
+        catta_log_error(__FILE__": SO_PASSCRED: %s", strerror(errno));
+        goto fail;
+    }
+
+    if (!(nl = catta_new(CattaNetlink, 1))) {
+        catta_log_error(__FILE__": catta_new() failed.");
+        goto fail;
+    }
+
+    nl->poll_api = poll_api;
+    nl->fd = fd;
+    nl->seq = 0;
+    nl->callback = cb;
+    nl->userdata = userdata;
+
+    if (!(nl->buffer = catta_new(uint8_t, nl->buffer_length = 64*1024))) {
+        catta_log_error(__FILE__": catta_new() failed.");
+        goto fail;
+    }
+
+    if (!(nl->watch = poll_api->watch_new(poll_api, fd, CATTA_WATCH_IN, socket_event, nl))) {
+        catta_log_error(__FILE__": Failed to create watch.");
+        goto fail;
+    }
+
+    return nl;
+
+fail:
+
+    if (fd >= 0)
+        close(fd);
+
+    if (nl) {
+        catta_free(nl->buffer);
+        catta_free(nl);
+    }
+
+    return NULL;
+}
+
+void catta_netlink_free(CattaNetlink *nl) {
+    assert(nl);
+
+    if (nl->watch)
+        nl->poll_api->watch_free(nl->watch);
+
+    if (nl->fd >= 0)
+        close(nl->fd);
+
+    catta_free(nl->buffer);
+    catta_free(nl);
+}
+
+int catta_netlink_send(CattaNetlink *nl, struct nlmsghdr *m, unsigned *ret_seq) {
+    assert(nl);
+    assert(m);
+
+    m->nlmsg_seq = nl->seq++;
+    m->nlmsg_flags |= NLM_F_ACK;
+
+    if (send(nl->fd, m, m->nlmsg_len, 0) < 0) {
+        catta_log_error(__FILE__": send(): %s", strerror(errno));
+        return -1;
+    }
+
+    if (ret_seq)
+        *ret_seq = m->nlmsg_seq;
+
+    return 0;
+}