Clear up mainloop()

* Replace if/else/... by a switch()
* Fix debug line that did not support new commands
* Only check len is oversized when len is used
* Check for disconnect after check for magic number, not before

diff --git a/nbd-server.c b/nbd-server.c
index 3343d9d..a99c27b 100644 (file)
--- a/nbd-server.c
+++ b/nbd-server.c
@@ -261,6 +261,22 @@ typedef struct {
                                  is PARAM_BOOL. */
 } PARAM;
 
+static inline const char * getcommandname(uint64_t command) {
+       switch (command) {
+       case NBD_CMD_READ:
+               return "NBD_CMD_READ";
+       case NBD_CMD_WRITE:
+               return "NBD_CMD_WRITE";
+       case NBD_CMD_DISC:
+               return "NBD_CMD_DISC";
+       case NBD_CMD_FLUSH:
+               return "NBD_CMD_FLUSH";
+       default:
+               break;
+       }
+       return "UNKNOWN";
+}
+
 /**
  * Check whether a client is allowed to connect. Works with an authorization
  * file which contains one line per machine, no wildcards.
@@ -1458,32 +1474,15 @@ int mainloop(CLIENT *client) {
                request.from = ntohll(request.from);
                request.type = ntohl(request.type);
                command = request.type & NBD_CMD_MASK_COMMAND;
-
-               if (command==NBD_CMD_DISC) {
-                       msg2(LOG_INFO, "Disconnect request received.");
-                       if (client->server->flags & F_COPYONWRITE) { 
-                               if (client->difmap) g_free(client->difmap) ;
-                               close(client->difffile);
-                               unlink(client->difffilename);
-                               free(client->difffilename);
-                       }
-                       go_on=FALSE;
-                       continue;
-               }
-
                len = ntohl(request.len);
 
+               DEBUG("%s from %llu (%llu) len %d, ", getcommandname(command),
+                               (unsigned long long)request.from,
+                               (unsigned long long)request.from / 512, (unsigned int)len);
+
                if (request.magic != htonl(NBD_REQUEST_MAGIC))
                        err("Not enough magic.");
-               if (len > BUFSIZE - sizeof(struct nbd_reply)) {
-                       currlen = BUFSIZE - sizeof(struct nbd_reply);
-                       msg2(LOG_INFO, "oversized request (this is not a problem)");
-               } else {
-                       currlen = len;
-               }
-               DEBUG("%s from %llu (%llu) len %d, ", command ? "WRITE" :
-                               "READ", (unsigned long long)request.from,
-                               (unsigned long long)request.from / 512, (unsigned int)len);
+
                memcpy(reply.handle, request.handle, sizeof(reply.handle));
 
                if ((command==NBD_CMD_WRITE) || (command==NBD_CMD_READ)) {
@@ -1498,9 +1497,28 @@ int mainloop(CLIENT *client) {
                                ERROR(client, reply, EINVAL);
                                continue;
                        }
+
+                       currlen = len;
+                       if (currlen > BUFSIZE - sizeof(struct nbd_reply)) {
+                               currlen = BUFSIZE - sizeof(struct nbd_reply);
+                               msg2(LOG_INFO, "oversized request (this is not a problem)");
+                       }
                }
 
-               if (command==NBD_CMD_WRITE) {
+               switch (command) {
+
+               case NBD_CMD_DISC:
+                       msg2(LOG_INFO, "Disconnect request received.");
+                       if (client->server->flags & F_COPYONWRITE) { 
+                               if (client->difmap) g_free(client->difmap) ;
+                               close(client->difffile);
+                               unlink(client->difffilename);
+                               free(client->difffilename);
+                       }
+                       go_on=FALSE;
+                       continue;
+
+               case NBD_CMD_WRITE:
                        DEBUG("wr: net->buf, ");
                        while(len > 0) {
                                readit(client->net, buf, currlen);
@@ -1518,14 +1536,13 @@ int mainloop(CLIENT *client) {
                                        continue;
                                }
                                SEND(client->net, reply);
-                               DEBUG("OK!\n");
                                len -= currlen;
                                currlen = (len < BUFSIZE) ? len : BUFSIZE;
                        }
+                       DEBUG("OK!\n");
                        continue;
-               }
 
-               if (command==NBD_CMD_FLUSH) {
+               case NBD_CMD_FLUSH:
                        DEBUG("fl: ");
                        if (expflush(client)) {
                                DEBUG("Flush failed: %m");
@@ -1535,9 +1552,8 @@ int mainloop(CLIENT *client) {
                        SEND(client->net, reply);
                        DEBUG("OK!\n");
                        continue;
-               }
 
-               if (command==NBD_CMD_READ) {
+               case NBD_CMD_READ:
                        DEBUG("exp->buf, ");
                        memcpy(buf, &reply, sizeof(struct nbd_reply));
                        if (client->transactionlogfd != -1)
@@ -1561,9 +1577,11 @@ int mainloop(CLIENT *client) {
                        }
                        DEBUG("OK!\n");
                        continue;
-               }
 
-               DEBUG ("Ignoring unknown command\n");
+               default:
+                       DEBUG ("Ignoring unknown command\n");
+                       continue;
+               }
        }
        return 0;
 }