nbd-server: Limit the number of connections
[nbd.git] / nbd-server.c
index 1b665b9..820458c 100644 (file)
 #define MY_NAME "nbd_server"
 #include "cliserv.h"
 
+#ifdef WITH_SDP
+#include <sdp_inet.h>
+#endif
+
 /** Default position of the config file */
 #ifndef SYSCONFDIR
 #define SYSCONFDIR "/etc"
@@ -200,6 +204,7 @@ typedef struct {
        gchar* postrun;      /**< command that will be ran after the client
                                  disconnects */
        gchar* servename;    /**< name of the export as selected by nbd-client */
+       int max_connections; /**< maximum number of opened connections */
 } SERVER;
 
 /**
@@ -354,14 +359,15 @@ inline void writeit(int f, void *buf, size_t len) {
  */
 void usage() {
        printf("This is nbd-server version " VERSION "\n");
-       printf("Usage: [ip:|ip6@]port file_to_export [size][kKmM] [-l authorize_file] [-r] [-m] [-c] [-C configuration file] [-p PID file name] [-o section name]\n"
+       printf("Usage: [ip:|ip6@]port file_to_export [size][kKmM] [-l authorize_file] [-r] [-m] [-c] [-C configuration file] [-p PID file name] [-o section name] [-M max connections]\n"
               "\t-r|--read-only\t\tread only\n"
               "\t-m|--multi-file\t\tmultiple file\n"
               "\t-c|--copy-on-write\tcopy on write\n"
               "\t-C|--config-file\tspecify an alternate configuration file\n"
               "\t-l|--authorize-file\tfile with list of hosts that are allowed to\n\t\t\t\tconnect.\n"
               "\t-p|--pid-file\t\tspecify a filename to write our PID to\n"
-              "\t-o|--output-config\toutput a config file section for what you\n\t\t\t\tspecified on the command line, with the\n\t\t\t\tspecified section name\n\n"
+              "\t-o|--output-config\toutput a config file section for what you\n\t\t\t\tspecified on the command line, with the\n\t\t\t\tspecified section name\n"
+              "\t-M|--max-connections\tspecify the maximum number of opened connections\n\n"
               "\tif port is set to 0, stdin is used (for running from inetd)\n"
               "\tif file_to_export contains '%%s', it is substituted with the IP\n"
               "\t\taddress of the machine trying to connect\n" 
@@ -411,6 +417,7 @@ SERVER* cmdline(int argc, char *argv[]) {
                {"config-file", required_argument, NULL, 'C'},
                {"pid-file", required_argument, NULL, 'p'},
                {"output-config", required_argument, NULL, 'o'},
+               {"max-connection", required_argument, NULL, 'M'},
                {0,0,0,0}
        };
        SERVER *serve;
@@ -427,7 +434,7 @@ SERVER* cmdline(int argc, char *argv[]) {
        serve=g_new0(SERVER, 1);
        serve->authname = g_strdup(default_authname);
        serve->virtstyle=VIRT_IPLIT;
-       while((c=getopt_long(argc, argv, "-C:cl:mo:rp:", long_options, &i))>=0) {
+       while((c=getopt_long(argc, argv, "-C:cl:mo:rp:M:", long_options, &i))>=0) {
                switch (c) {
                case 1:
                        /* non-option argument */
@@ -504,6 +511,9 @@ SERVER* cmdline(int argc, char *argv[]) {
                        g_free(serve->authname);
                        serve->authname=g_strdup(optarg);
                        break;
+               case 'M':
+                       serve->max_connections = strtol(optarg, NULL, 0);
+                       break;
                default:
                        usage();
                        exit(EXIT_FAILURE);
@@ -515,6 +525,8 @@ SERVER* cmdline(int argc, char *argv[]) {
        if(nonspecial<2) {
                g_free(serve);
                serve=NULL;
+       } else {
+               do_oldstyle = TRUE;
        }
        if(do_output) {
                if(!serve) {
@@ -600,6 +612,8 @@ SERVER* dup_serve(SERVER *s) {
        if(s->servename)
                serve->servename = g_strdup(s->servename);
 
+       serve->max_connections = s->max_connections;
+
        return serve;
 }
 
@@ -699,6 +713,7 @@ GArray* parse_cfile(gchar* f, GError** e) {
                { "sdp",        FALSE,  PARAM_BOOL,     NULL, F_SDP },
                { "sync",       FALSE,  PARAM_BOOL,     NULL, F_SYNC },
                { "listenaddr", FALSE,  PARAM_STRING,   NULL, 0 },
+               { "maxconnections", FALSE, PARAM_INT,   NULL, 0 },
        };
        const int lp_size=sizeof(lp)/sizeof(PARAM);
        PARAM gp[] = {
@@ -749,6 +764,7 @@ GArray* parse_cfile(gchar* f, GError** e) {
                                lp[10].target=lp[11].target=
                                lp[12].target=&(s.flags);
                lp[13].target=&(s.listenaddr);
+               lp[14].target=&(s.max_connections);
 
                /* After the [generic] group, start parsing exports */
                if(i==1) {
@@ -832,6 +848,10 @@ GArray* parse_cfile(gchar* f, GError** e) {
                                g_key_file_free(cfile);
                                return NULL;
                        }
+                       if(s.port && !do_oldstyle) {
+                               g_warning("A port was specified, but oldstyle exports were not requested. This may not do what you expect.");
+                               g_warning("Please read 'man 5 nbd-server' and search for oldstyle for more info");
+                       }
                } else {
                        s.virtstyle=VIRT_IPLIT;
                }
@@ -1226,12 +1246,19 @@ CLIENT* negotiate(int net, CLIENT *client, GArray* servers) {
 
        memset(zeros, '\0', sizeof(zeros));
        if(!client || !client->modern) {
+               /* common */
                if (write(net, INIT_PASSWD, 8) < 0) {
                        err_nonfatal("Negotiation failed: %m");
                        if(client)
                                exit(EXIT_FAILURE);
                }
-               magic = htonll(opts_magic);
+               if(!client || client->modern) {
+                       /* modern */
+                       magic = htonll(opts_magic);
+               } else {
+                       /* oldstyle */
+                       magic = htonll(cliserv_magic);
+               }
                if (write(net, &magic, sizeof(magic)) < 0) {
                        err_nonfatal("Negotiation failed: %m");
                        if(client)
@@ -1239,33 +1266,40 @@ CLIENT* negotiate(int net, CLIENT *client, GArray* servers) {
                }
        }
        if(!client) {
-               uint64_t reserved;
+               /* modern */
+               uint32_t reserved;
                uint32_t opt;
-               uint64_t namelen;
+               uint32_t namelen;
                char* name;
                int i;
 
                if(!servers)
                        err("programmer error");
-               write(net, &smallflags, sizeof(uint16_t));
-               read(net, &reserved, sizeof(reserved));
-               read(net, &magic, sizeof(magic));
+               if (write(net, &smallflags, sizeof(uint16_t)) < 0)
+                       err("Negotiation failed: %m");
+               if (read(net, &reserved, sizeof(reserved)) < 0)
+                       err("Negotiation failed: %m");
+               if (read(net, &magic, sizeof(magic)) < 0)
+                       err("Negotiation failed: %m");
                magic = ntohll(magic);
-               if(magic != cliserv_magic) {
+               if(magic != opts_magic) {
                        close(net);
                        return NULL;
                }
-               read(net, &opt, sizeof(opt));
+               if (read(net, &opt, sizeof(opt)) < 0)
+                       err("Negotiation failed: %m");
                opt = ntohl(opt);
                if(opt != NBD_OPT_EXPORT_NAME) {
                        close(net);
                        return NULL;
                }
-               read(net, &namelen, sizeof(namelen));
-               namelen = ntohll(namelen);
+               if (read(net, &namelen, sizeof(namelen)) < 0)
+                       err("Negotiation failed: %m");
+               namelen = ntohl(namelen);
                name = malloc(namelen+1);
-               name[namelen+1]=0;
-               read(net, name, namelen);
+               name[namelen]=0;
+               if (read(net, name, namelen) < 0)
+                       err("Negotiation failed: %m");
                for(i=0; i<servers->len; i++) {
                        SERVER* serve = &(g_array_index(servers, SERVER, i));
                        if(!strcmp(serve->servename, name)) {
@@ -1277,22 +1311,28 @@ CLIENT* negotiate(int net, CLIENT *client, GArray* servers) {
                                return client;
                        }
                }
+               return NULL;
        }
+       /* common */
        size_host = htonll((u64)(client->exportsize));
        if (write(net, &size_host, 8) < 0)
                err("Negotiation failed: %m");
        if (client->server->flags & F_READONLY)
                flags |= NBD_FLAG_READ_ONLY;
        if (!client->modern) {
-       flags = htonl(flags);
+               /* oldstyle */
+               flags = htonl(flags);
                if (write(client->net, &flags, 4) < 0)
                        err("Negotiation failed: %m");
        } else {
+               /* modern */
                smallflags = (uint16_t)(flags & ~((uint16_t)0));
+               smallflags = htons(smallflags);
                if (write(client->net, &smallflags, sizeof(smallflags)) < 0) {
                        err("Negotiation failed: %m");
                }
        }
+       /* common */
        if (write(client->net, zeros, 124) < 0)
                err("Negotiation failed: %m");
        return NULL;
@@ -1696,6 +1736,7 @@ int serveloop(GArray* servers) {
                                if(!client) {
                                        err_nonfatal("negotiation failed");
                                        close(net);
+                                       net=0;
                                }
                        }
                        for(i=0;i<servers->len && !net;i++) {
@@ -1708,6 +1749,12 @@ int serveloop(GArray* servers) {
                        if(net) {
                                int sock_flags;
 
+                               if(serve->max_connections > 0 &&
+                                  g_hash_table_size(children) >= serve->max_connections) {
+                                       msg2(LOG_INFO, "Max connections reached");
+                                       close(net);
+                                       continue;
+                               }
                                if((sock_flags = fcntl(net, F_GETFL, 0))==-1) {
                                        err("fcntl F_GETFL");
                                }
@@ -2019,7 +2066,7 @@ void glib_message_syslog_redirect(const gchar *log_domain,
       default:
         level=LOG_ERR;
     }
-    syslog(level, message);
+    syslog(level, "%s", message);
 }
 #endif
 
@@ -2072,8 +2119,11 @@ int main(int argc, char *argv[]) {
        }
     
        if(!servers || !servers->len) {
-               g_warning("Could not parse config file: %s", 
-                               err ? err->message : "Unknown error");
+               if(err && !(err->domain == g_quark_from_string("parse_cfile")
+                               && err->code == CFILE_NOTFOUND)) {
+                       g_warning("Could not parse config file: %s", 
+                                       err ? err->message : "Unknown error");
+               }
        }
        if(serve) {
                g_warning("Specifying an export on the command line is deprecated.");
@@ -2081,7 +2131,7 @@ int main(int argc, char *argv[]) {
        }
 
        if((!serve) && (!servers||!servers->len)) {
-               g_message("Nothing to do! Bye!");
+               g_message("No configured exports; quitting.");
                exit(EXIT_FAILURE);
        }
        daemonize(serve);