libcephfs_proxy: add support for control messages

The negotiation protocol will require sending control messages over the
unix socket. This commit implements send and receive functions that
include control messages.

Signed-off-by: Xavi Hernandez <xhernandez@gmail.com>

diff --git a/src/libcephfs_proxy/proxy_link.c b/src/libcephfs_proxy/proxy_link.c
index 506b4dd6bbff44c92ebcd14d4cfe1c0ab0b635b2..ad61c2724c2928a912aead1d423cfafb981eda2c 100644 (file)
--- a/src/libcephfs_proxy/proxy_link.c
+++ b/src/libcephfs_proxy/proxy_link.c
@@ -111,6 +111,117 @@ static int32_t proxy_link_write(proxy_link_t *link, int32_t sd, void *buffer,
        return 0;
 }
 
+int32_t proxy_link_ctrl_send(int32_t sd, void *data, int32_t size, int32_t type,
+                            void *ctrl, int32_t ctrl_size)
+{
+       char buffer[CMSG_SPACE(ctrl_size)];
+       struct msghdr msg;
+       struct iovec iov;
+       struct cmsghdr *cmsg;
+       ssize_t len;
+
+       msg.msg_name = NULL;
+       msg.msg_namelen = 0;
+
+       iov.iov_base = data;
+       iov.iov_len = size;
+       msg.msg_iov = &iov;
+       msg.msg_iovlen = 1;
+
+       cmsg = (struct cmsghdr *)buffer;
+       cmsg->cmsg_len = CMSG_LEN(ctrl_size);
+       cmsg->cmsg_level = SOL_SOCKET;
+       cmsg->cmsg_type = type;
+       memcpy(CMSG_DATA(cmsg), ctrl, ctrl_size);
+       msg.msg_control = buffer;
+       msg.msg_controllen = sizeof(buffer);
+
+       msg.msg_flags = 0;
+
+       len = sendmsg(sd, &msg, MSG_NOSIGNAL);
+       if (len < 0) {
+               return proxy_log(LOG_ERR, errno,
+                                "Failed to send a control message");
+       }
+
+       if (len != size) {
+               return proxy_log(LOG_ERR, 0,
+                                "Control message not sent completely");
+       }
+
+       return 0;
+}
+
+int32_t proxy_link_ctrl_recv(int32_t sd, void *data, int32_t size, int32_t type,
+                            void *ctrl, int32_t *ctrl_size)
+{
+       char buffer[CMSG_SPACE(*ctrl_size)];
+       struct msghdr msg;
+       struct iovec iov;
+       struct cmsghdr *cmsg;
+       ssize_t len;
+       int32_t clen;
+
+       msg.msg_name = NULL;
+       msg.msg_namelen = 0;
+
+       iov.iov_base = data;
+       iov.iov_len = size;
+       msg.msg_iov = &iov;
+       msg.msg_iovlen = 1;
+
+       msg.msg_control = buffer;
+       msg.msg_controllen = sizeof(buffer);
+
+       msg.msg_flags = 0;
+
+       len = recvmsg(sd, &msg, MSG_NOSIGNAL | MSG_CMSG_CLOEXEC);
+       if (len < 0) {
+               return proxy_log(LOG_ERR, errno,
+                                "Failed to received a control message");
+       }
+
+       if (len != size) {
+               return proxy_log(LOG_ERR, 0,
+                                "Message data not received completely");
+       }
+
+       if ((msg.msg_flags & MSG_CTRUNC) != 0) {
+               return proxy_log(LOG_ERR, ENOSPC,
+                                "Message data is larger than expected");
+       }
+
+       cmsg = CMSG_FIRSTHDR(&msg);
+       if (cmsg == NULL) {
+               *ctrl_size = 0;
+               return len;
+       }
+
+       if (cmsg->cmsg_level != SOL_SOCKET) {
+               return proxy_log(LOG_ERR, EINVAL,
+                                "Unexpected control message level");
+       }
+
+       if (cmsg->cmsg_type != type) {
+               return proxy_log(LOG_ERR, EINVAL,
+                                "Unexpected control message type");
+       }
+
+       clen = cmsg->cmsg_len - CMSG_LEN(0);
+       if (clen != *ctrl_size) {
+               return proxy_log(LOG_ERR, EINVAL,
+                                "Unexpected control message size");
+       }
+
+       if (CMSG_NXTHDR(&msg, cmsg) != NULL) {
+               return proxy_log(LOG_ERR, EINVAL, "Too many control messages");
+       }
+
+       memcpy(ctrl, CMSG_DATA(cmsg), clen);
+
+       return len;
+}
+
 int32_t proxy_link_client(proxy_link_t *link, const char *path,
                          proxy_link_stop_t stop)
 {

diff --git a/src/libcephfs_proxy/proxy_link.h b/src/libcephfs_proxy/proxy_link.h
index 163e74121219edfce818d741fbf6d8abc93b6a0c..ae24b2ff931294ff419eac0a0c44749f3b663ff4 100644 (file)
--- a/src/libcephfs_proxy/proxy_link.h
+++ b/src/libcephfs_proxy/proxy_link.h
@@ -58,4 +58,10 @@ int32_t proxy_link_request(int32_t sd, int32_t op, struct iovec *req_iov,
                           int32_t req_count, struct iovec *ans_iov,
                           int32_t ans_count);
 
+int32_t proxy_link_ctrl_send(int32_t sd, void *data, int32_t size, int32_t type,
+                            void *ctrl, int32_t ctrl_size);
+
+int32_t proxy_link_ctrl_recv(int32_t sd, void *data, int32_t size, int32_t type,
+                            void *ctrl, int32_t *ctrl_size);
+
 #endif