diff --git a/README.qemu-mcast b/README.qemu-mcast new file mode 100644 index 0000000..4021be5 --- /dev/null +++ b/README.qemu-mcast @@ -0,0 +1,56 @@ +QEMU multicast support +====================== +Author: JuanJo Ciarlante jjo()um.edu.ar, juanjosec()gmail.com +Date: Mon Dec 12 12:38:11 ART 2005 +Keywords: qemu, socket, multicast, UDP, mcast, UML + +Attached patch (against qemu CVS 2005-12-10) adds multicast support for +QEMU socket transport, ie: run several stateless possibly non-local QEMUs +on same virtual ethernet "BUS". +User-mode-linux (UML) compatible (tested). + +An excerpt from qemu-doc.texi: + + `-net socket[,vlan=n][,fd=h][,mcast=maddr:port]' + Create a VLAN n shared with another QEMU virtual machines using + a UDP multicast socket, effectively making a bus for every QEMU + with same multicast address maddr and port. NOTES: + 1. Several QEMU can be running on different hosts and share same + bus (assuming correct multicast setup for these hosts). + 2. mcast support is compatible with User Mode Linux (argument + `ethN=mcast'), see http://user-mode-linux.sf.net. + Example: + # launch one QEMU instance + qemu linux.img -net nic,macaddr=52:54:00:12:34:56 -net socket,mcast=230.0.0.1:1234 + # launch another QEMU instance on same "bus" + qemu linux.img -net nic,macaddr=52:54:00:12:34:57 -net socket,mcast=230.0.0.1:1234 + # launch yet another QEMU instance on same "bus" + qemu linux.img -net nic,macaddr=52:54:00:12:34:58 -net socket,mcast=230.0.0.1:1234 + Example (User Mode Linux compat.): + # launch QEMU instance (note mcast address selected is UML's default) + qemu linux.img -net nic,macaddr=52:54:00:12:34:56 -net socket,mcast=239.192.168.1:1102 + # launch UML + /path/to/linux ubd0=/path/to/root_fs eth0=mcast + +Available under GPLv2 from + http://www.irrigacion.gov.ar/juanjo/qemu/ + + +Changes +------- +v4 (2005-12-12): + * Tested mcast user-mode-linux compatibility + * Minor tweaks + +v3 (2005-12-07): + * correctly close fds if any socket syscall fails (ie. close'em don't leak'em ;) + +v2 (2005-12-07): + * 1st public release + + +--Juanjo + +# Juan Jose Ciarlante (JuanJo) jjo ;at; mendoza.gov.ar # +# GnuPG Public Key: gpg --keyserver wwwkeys.eu.pgp.net --recv-key 66727177 # +# Key fingerprint: 0D2F 3E5D 8B5C 729E 0560 F453 A3F7 E249 6672 7177 # diff --git a/qemu-doc.texi b/qemu-doc.texi index 7ec41f5..d630adf 100644 --- a/qemu-doc.texi +++ b/qemu-doc.texi @@ -293,6 +293,41 @@ qemu linux.img -net nic,macaddr=52:54:00 qemu linux.img -net nic,macaddr=52:54:00:12:34:57 -net socket,connect=127.0.0.1:1234 @end example address@hidden -net socket[,vlan=n][,fd=h][,mcast=maddr:port] + +Create a VLAN @var{n} shared with another QEMU virtual +machines using a UDP multicast socket, effectively making a bus for +every QEMU with same multicast address @var{maddr} and @var{port}. +NOTES: address@hidden address@hidden +Several QEMU can be running on different hosts and share same bus (assuming +correct multicast setup for these hosts). address@hidden +mcast support is compatible with User Mode Linux (argument @address@hidden), see address@hidden address@hidden enumerate + + +Example: address@hidden +# launch one QEMU instance +qemu linux.img -net nic,macaddr=52:54:00:12:34:56 -net socket,mcast=230.0.0.1:1234 +# launch another QEMU instance on same "bus" +qemu linux.img -net nic,macaddr=52:54:00:12:34:57 -net socket,mcast=230.0.0.1:1234 +# launch yet another QEMU instance on same "bus" +qemu linux.img -net nic,macaddr=52:54:00:12:34:58 -net socket,mcast=230.0.0.1:1234 address@hidden example + +Example (User Mode Linux compat.): address@hidden +# launch QEMU instance (note mcast address selected is UML's default) +qemu linux.img -net nic,macaddr=52:54:00:12:34:56 -net socket,mcast=239.192.168.1:1102 +# launch UML +/path/to/linux ubd0=/path/to/root_fs eth0=mcast address@hidden example + + @item -net none Indicate that no network devices should be configured. It is used to override the default configuration which is activated if no diff --git a/vl.c b/vl.c index 4b1e72e..4492418 100644 --- a/vl.c +++ b/vl.c @@ -2131,8 +2131,17 @@ typedef struct NetSocketState { int index; int packet_len; uint8_t buf[4096]; + struct sockaddr_in dgram_dst; /* contains inet host and port destination iff connectionless (SOCK_DGRAM) */ } NetSocketState; +static int qemu_socket_is_dgram(const struct NetSocketState *s) +{ + /* This could also be: getsockopt(s->fd, SOL_SOCKET, SO_TYPE, &opt, &optlen) + * but I would cost an extra syscall per write (DGRAM writes don't require sending pkt length) + */ + return (s->dgram_dst.sin_addr.s_addr!=0); +} + typedef struct NetSocketListenState { VLANState *vlan; int fd; @@ -2145,8 +2154,12 @@ static void net_socket_receive(void *opa uint32_t len; len = htonl(size); - unix_write(s->fd, (const uint8_t *)&len, sizeof(len)); - unix_write(s->fd, buf, size); + if (qemu_socket_is_dgram(s)) { + sendto(s->fd, buf, size, 0, (struct sockaddr *)&s->dgram_dst, sizeof(s->dgram_dst)); + } else { + unix_write(s->fd, (const uint8_t *)&len, sizeof(len)); + unix_write(s->fd, buf, size); + } } static void net_socket_send(void *opaque) @@ -2164,6 +2177,11 @@ static void net_socket_send(void *opaque qemu_set_fd_handler(s->fd, NULL, NULL, NULL); return; } + if (qemu_socket_is_dgram(s)) { + s->index = 0; + s->state = 1; + s->packet_len = size; + } buf = buf1; while (size > 0) { /* reassemble a packet from the network */ @@ -2336,6 +2354,75 @@ static int net_socket_connect_init(VLANS return 0; } +static int net_socket_mcast_init(VLANState *vlan, const char *host_str) +{ + NetSocketState *s; + int fd=-1, ret, val; + struct sockaddr_in saddr; + struct ip_mreq imr; + + if (parse_host_port(&saddr, host_str) < 0) + return -1; + + if (!IN_MULTICAST(ntohl(saddr.sin_addr.s_addr))) { + fprintf(stderr, "qemu: error: specified mcastaddr \"%s\" (0x%08x) does not contain a multicast address\n", + inet_ntoa(saddr.sin_addr), ntohl(saddr.sin_addr.s_addr)); + return -1; + + } + fd = socket(PF_INET, SOCK_DGRAM, 0); + if (fd < 0) { + perror("socket(PF_INET, SOCK_DGRAM)"); + return -1; + } + + /* Add host to multicast group */ + imr.imr_multiaddr = saddr.sin_addr; + imr.imr_interface.s_addr = htonl(INADDR_ANY); + + ret = setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, (void *) &imr, sizeof(struct ip_mreq)); + if (ret < 0) { + perror("setsockopt(IP_ADD_MEMBERSHIP)"); + goto fail; + } + + /* Force mcast msgs to loopback (eg. several QEMUs in same host */ + val = 1; + ret=setsockopt(fd, SOL_IP, IP_MULTICAST_LOOP, &val, sizeof(val)); + if (ret < 0) { + perror("setsockopt(SOL_IP, IP_MULTICAST_LOOP)"); + goto fail; + } + ret=setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val)); + if (ret < 0) { + perror("setsockopt(SOL_SOCKET, SO_REUSEADDR)"); + goto fail; + } + + ret = bind(fd, (struct sockaddr *)&saddr, sizeof(saddr)); + if (ret < 0) { + perror("bind"); + goto fail; + } + + fcntl(fd, F_SETFL, O_NONBLOCK); + + s = net_socket_fd_init(vlan, fd, 1); + if (!s) + goto fail; + + /* Connectionless: save mcast address for sendto() */ + s->dgram_dst = saddr; + + snprintf(s->vc->info_str, sizeof(s->vc->info_str), + "socket: mcast at %s:%d", + inet_ntoa(saddr.sin_addr), ntohs(saddr.sin_port)); + return 0; +fail: + if (fd>=0) close(fd); + return -1; +} + #endif /* !_WIN32 */ static int get_param_value(char *buf, int buf_size, @@ -2472,6 +2559,8 @@ int net_client_init(const char *str) ret = net_socket_listen_init(vlan, buf); } else if (get_param_value(buf, sizeof(buf), "connect", p) > 0) { ret = net_socket_connect_init(vlan, buf); + } else if (get_param_value(buf, sizeof(buf), "mcast", p) > 0) { + ret = net_socket_mcast_init(vlan, buf); } else { fprintf(stderr, "Unknown socket options: %s\n", p); return -1; @@ -3810,6 +3899,8 @@ void help(void) " use 'fd=h' to connect to an already opened TAP interface\n" "-net socket[,vlan=n][,fd=h][,listen=[host]:port][,connect=host:port]\n" " connect the vlan 'n' to another VLAN using a socket connection\n" + "-net socket[,vlan=n][,fd=h][,mcast=maddr:port]\n" + " create a vlan 'n' with another QEMUs on multicast maddr and port\n" #endif "-net none use it alone to have zero network devices; if no -net option\n" " is provided, the default is '-net nic -net user'\n"