net: move slirp code from net.c to net/slirp.c

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

2 files changed, 803 insertions, 0 deletions

diff --git a/net/slirp.c b/net/slirp.c
new file mode 100644
index 0000000000..d6d57721dd
--- /dev/null
+++ b/net/slirp.c
@@ -0,0 +1,752 @@
+/*
+ * QEMU System Emulator
+ *
+ * Copyright (c) 2003-2008 Fabrice Bellard
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#include "net/slirp.h"
+
+#include "config-host.h"
+
+#include "net.h"
+#include "monitor.h"
+#include "sysemu.h"
+#include "qemu_socket.h"
+#include "slirp/libslirp.h"
+
+static int get_str_sep(char *buf, int buf_size, const char **pp, int sep)
+{
+    const char *p, *p1;
+    int len;
+    p = *pp;
+    p1 = strchr(p, sep);
+    if (!p1)
+        return -1;
+    len = p1 - p;
+    p1++;
+    if (buf_size > 0) {
+        if (len > buf_size - 1)
+            len = buf_size - 1;
+        memcpy(buf, p, len);
+        buf[len] = '\0';
+    }
+    *pp = p1;
+    return 0;
+}
+
+/* slirp network adapter */
+
+#define SLIRP_CFG_HOSTFWD 1
+#define SLIRP_CFG_LEGACY  2
+
+struct slirp_config_str {
+    struct slirp_config_str *next;
+    int flags;
+    char str[1024];
+    int legacy_format;
+};
+
+typedef struct SlirpState {
+    QTAILQ_ENTRY(SlirpState) entry;
+    VLANClientState *vc;
+    Slirp *slirp;
+#ifndef _WIN32
+    char smb_dir[128];
+#endif
+} SlirpState;
+
+static struct slirp_config_str *slirp_configs;
+const char *legacy_tftp_prefix;
+const char *legacy_bootp_filename;
+static QTAILQ_HEAD(slirp_stacks, SlirpState) slirp_stacks =
+    QTAILQ_HEAD_INITIALIZER(slirp_stacks);
+
+static int slirp_hostfwd(SlirpState *s, const char *redir_str,
+                         int legacy_format);
+static int slirp_guestfwd(SlirpState *s, const char *config_str,
+                          int legacy_format);
+
+#ifndef _WIN32
+static const char *legacy_smb_export;
+
+static int slirp_smb(SlirpState *s, const char *exported_dir,
+                     struct in_addr vserver_addr);
+static void slirp_smb_cleanup(SlirpState *s);
+#else
+static inline void slirp_smb_cleanup(SlirpState *s) { }
+#endif
+
+int slirp_can_output(void *opaque)
+{
+    SlirpState *s = opaque;
+
+    return qemu_can_send_packet(s->vc);
+}
+
+void slirp_output(void *opaque, const uint8_t *pkt, int pkt_len)
+{
+    SlirpState *s = opaque;
+
+    qemu_send_packet(s->vc, pkt, pkt_len);
+}
+
+static ssize_t slirp_receive(VLANClientState *vc, const uint8_t *buf, size_t size)
+{
+    SlirpState *s = vc->opaque;
+
+    slirp_input(s->slirp, buf, size);
+
+    return size;
+}
+
+static void net_slirp_cleanup(VLANClientState *vc)
+{
+    SlirpState *s = vc->opaque;
+
+    slirp_cleanup(s->slirp);
+    slirp_smb_cleanup(s);
+    QTAILQ_REMOVE(&slirp_stacks, s, entry);
+    qemu_free(s);
+}
+
+static int net_slirp_init(VLANState *vlan, const char *model,
+                          const char *name, int restricted,
+                          const char *vnetwork, const char *vhost,
+                          const char *vhostname, const char *tftp_export,
+                          const char *bootfile, const char *vdhcp_start,
+                          const char *vnameserver, const char *smb_export,
+                          const char *vsmbserver)
+{
+    /* default settings according to historic slirp */
+    struct in_addr net  = { .s_addr = htonl(0x0a000200) }; /* 10.0.2.0 */
+    struct in_addr mask = { .s_addr = htonl(0xffffff00) }; /* 255.255.255.0 */
+    struct in_addr host = { .s_addr = htonl(0x0a000202) }; /* 10.0.2.2 */
+    struct in_addr dhcp = { .s_addr = htonl(0x0a00020f) }; /* 10.0.2.15 */
+    struct in_addr dns  = { .s_addr = htonl(0x0a000203) }; /* 10.0.2.3 */
+#ifndef _WIN32
+    struct in_addr smbsrv = { .s_addr = 0 };
+#endif
+    SlirpState *s;
+    char buf[20];
+    uint32_t addr;
+    int shift;
+    char *end;
+    struct slirp_config_str *config;
+
+    if (!tftp_export) {
+        tftp_export = legacy_tftp_prefix;
+    }
+    if (!bootfile) {
+        bootfile = legacy_bootp_filename;
+    }
+
+    if (vnetwork) {
+        if (get_str_sep(buf, sizeof(buf), &vnetwork, '/') < 0) {
+            if (!inet_aton(vnetwork, &net)) {
+                return -1;
+            }
+            addr = ntohl(net.s_addr);
+            if (!(addr & 0x80000000)) {
+                mask.s_addr = htonl(0xff000000); /* class A */
+            } else if ((addr & 0xfff00000) == 0xac100000) {
+                mask.s_addr = htonl(0xfff00000); /* priv. 172.16.0.0/12 */
+            } else if ((addr & 0xc0000000) == 0x80000000) {
+                mask.s_addr = htonl(0xffff0000); /* class B */
+            } else if ((addr & 0xffff0000) == 0xc0a80000) {
+                mask.s_addr = htonl(0xffff0000); /* priv. 192.168.0.0/16 */
+            } else if ((addr & 0xffff0000) == 0xc6120000) {
+                mask.s_addr = htonl(0xfffe0000); /* tests 198.18.0.0/15 */
+            } else if ((addr & 0xe0000000) == 0xe0000000) {
+                mask.s_addr = htonl(0xffffff00); /* class C */
+            } else {
+                mask.s_addr = htonl(0xfffffff0); /* multicast/reserved */
+            }
+        } else {
+            if (!inet_aton(buf, &net)) {
+                return -1;
+            }
+            shift = strtol(vnetwork, &end, 10);
+            if (*end != '\0') {
+                if (!inet_aton(vnetwork, &mask)) {
+                    return -1;
+                }
+            } else if (shift < 4 || shift > 32) {
+                return -1;
+            } else {
+                mask.s_addr = htonl(0xffffffff << (32 - shift));
+            }
+        }
+        net.s_addr &= mask.s_addr;
+        host.s_addr = net.s_addr | (htonl(0x0202) & ~mask.s_addr);
+        dhcp.s_addr = net.s_addr | (htonl(0x020f) & ~mask.s_addr);
+        dns.s_addr  = net.s_addr | (htonl(0x0203) & ~mask.s_addr);
+    }
+
+    if (vhost && !inet_aton(vhost, &host)) {
+        return -1;
+    }
+    if ((host.s_addr & mask.s_addr) != net.s_addr) {
+        return -1;
+    }
+
+    if (vdhcp_start && !inet_aton(vdhcp_start, &dhcp)) {
+        return -1;
+    }
+    if ((dhcp.s_addr & mask.s_addr) != net.s_addr ||
+        dhcp.s_addr == host.s_addr || dhcp.s_addr == dns.s_addr) {
+        return -1;
+    }
+
+    if (vnameserver && !inet_aton(vnameserver, &dns)) {
+        return -1;
+    }
+    if ((dns.s_addr & mask.s_addr) != net.s_addr ||
+        dns.s_addr == host.s_addr) {
+        return -1;
+    }
+
+#ifndef _WIN32
+    if (vsmbserver && !inet_aton(vsmbserver, &smbsrv)) {
+        return -1;
+    }
+#endif
+
+    s = qemu_mallocz(sizeof(SlirpState));
+    s->slirp = slirp_init(restricted, net, mask, host, vhostname,
+                          tftp_export, bootfile, dhcp, dns, s);
+    QTAILQ_INSERT_TAIL(&slirp_stacks, s, entry);
+
+    for (config = slirp_configs; config; config = config->next) {
+        if (config->flags & SLIRP_CFG_HOSTFWD) {
+            if (slirp_hostfwd(s, config->str,
+                              config->flags & SLIRP_CFG_LEGACY) < 0)
+                return -1;
+        } else {
+            if (slirp_guestfwd(s, config->str,
+                               config->flags & SLIRP_CFG_LEGACY) < 0)
+                return -1;
+        }
+    }
+#ifndef _WIN32
+    if (!smb_export) {
+        smb_export = legacy_smb_export;
+    }
+    if (smb_export) {
+        if (slirp_smb(s, smb_export, smbsrv) < 0)
+            return -1;
+    }
+#endif
+
+    s->vc = qemu_new_vlan_client(NET_CLIENT_TYPE_SLIRP,
+                                 vlan, NULL, model, name, NULL,
+                                 slirp_receive, NULL, NULL,
+                                 net_slirp_cleanup, s);
+    snprintf(s->vc->info_str, sizeof(s->vc->info_str),
+             "net=%s, restricted=%c", inet_ntoa(net), restricted ? 'y' : 'n');
+    return 0;
+}
+
+static SlirpState *slirp_lookup(Monitor *mon, const char *vlan,
+                                const char *stack)
+{
+    VLANClientState *vc;
+
+    if (vlan) {
+        vc = qemu_find_vlan_client_by_name(mon, strtol(vlan, NULL, 0), stack);
+        if (!vc) {
+            return NULL;
+        }
+        if (strcmp(vc->model, "user")) {
+            monitor_printf(mon, "invalid device specified\n");
+            return NULL;
+        }
+        return vc->opaque;
+    } else {
+        if (QTAILQ_EMPTY(&slirp_stacks)) {
+            monitor_printf(mon, "user mode network stack not in use\n");
+            return NULL;
+        }
+        return QTAILQ_FIRST(&slirp_stacks);
+    }
+}
+
+void net_slirp_hostfwd_remove(Monitor *mon, const QDict *qdict)
+{
+    struct in_addr host_addr = { .s_addr = INADDR_ANY };
+    int host_port;
+    char buf[256] = "";
+    const char *src_str, *p;
+    SlirpState *s;
+    int is_udp = 0;
+    int err;
+    const char *arg1 = qdict_get_str(qdict, "arg1");
+    const char *arg2 = qdict_get_try_str(qdict, "arg2");
+    const char *arg3 = qdict_get_try_str(qdict, "arg3");
+
+    if (arg2) {
+        s = slirp_lookup(mon, arg1, arg2);
+        src_str = arg3;
+    } else {
+        s = slirp_lookup(mon, NULL, NULL);
+        src_str = arg1;
+    }
+    if (!s) {
+        return;
+    }
+
+    if (!src_str || !src_str[0])
+        goto fail_syntax;
+
+    p = src_str;
+    get_str_sep(buf, sizeof(buf), &p, ':');
+
+    if (!strcmp(buf, "tcp") || buf[0] == '\0') {
+        is_udp = 0;
+    } else if (!strcmp(buf, "udp")) {
+        is_udp = 1;
+    } else {
+        goto fail_syntax;
+    }
+
+    if (get_str_sep(buf, sizeof(buf), &p, ':') < 0) {
+        goto fail_syntax;
+    }
+    if (buf[0] != '\0' && !inet_aton(buf, &host_addr)) {
+        goto fail_syntax;
+    }
+
+    host_port = atoi(p);
+
+    err = slirp_remove_hostfwd(QTAILQ_FIRST(&slirp_stacks)->slirp, is_udp,
+                               host_addr, host_port);
+
+    monitor_printf(mon, "host forwarding rule for %s %s\n", src_str,
+                   err ? "removed" : "not found");
+    return;
+
+ fail_syntax:
+    monitor_printf(mon, "invalid format\n");
+}
+
+static int slirp_hostfwd(SlirpState *s, const char *redir_str,
+                         int legacy_format)
+{
+    struct in_addr host_addr = { .s_addr = INADDR_ANY };
+    struct in_addr guest_addr = { .s_addr = 0 };
+    int host_port, guest_port;
+    const char *p;
+    char buf[256];
+    int is_udp;
+    char *end;
+
+    p = redir_str;
+    if (!p || get_str_sep(buf, sizeof(buf), &p, ':') < 0) {
+        goto fail_syntax;
+    }
+    if (!strcmp(buf, "tcp") || buf[0] == '\0') {
+        is_udp = 0;
+    } else if (!strcmp(buf, "udp")) {
+        is_udp = 1;
+    } else {
+        goto fail_syntax;
+    }
+
+    if (!legacy_format) {
+        if (get_str_sep(buf, sizeof(buf), &p, ':') < 0) {
+            goto fail_syntax;
+        }
+        if (buf[0] != '\0' && !inet_aton(buf, &host_addr)) {
+            goto fail_syntax;
+        }
+    }
+
+    if (get_str_sep(buf, sizeof(buf), &p, legacy_format ? ':' : '-') < 0) {
+        goto fail_syntax;
+    }
+    host_port = strtol(buf, &end, 0);
+    if (*end != '\0' || host_port < 1 || host_port > 65535) {
+        goto fail_syntax;
+    }
+
+    if (get_str_sep(buf, sizeof(buf), &p, ':') < 0) {
+        goto fail_syntax;
+    }
+    if (buf[0] != '\0' && !inet_aton(buf, &guest_addr)) {
+        goto fail_syntax;
+    }
+
+    guest_port = strtol(p, &end, 0);
+    if (*end != '\0' || guest_port < 1 || guest_port > 65535) {
+        goto fail_syntax;
+    }
+
+    if (slirp_add_hostfwd(s->slirp, is_udp, host_addr, host_port, guest_addr,
+                          guest_port) < 0) {
+        qemu_error("could not set up host forwarding rule '%s'\n",
+                   redir_str);
+        return -1;
+    }
+    return 0;
+
+ fail_syntax:
+    qemu_error("invalid host forwarding rule '%s'\n", redir_str);
+    return -1;
+}
+
+void net_slirp_hostfwd_add(Monitor *mon, const QDict *qdict)
+{
+    const char *redir_str;
+    SlirpState *s;
+    const char *arg1 = qdict_get_str(qdict, "arg1");
+    const char *arg2 = qdict_get_try_str(qdict, "arg2");
+    const char *arg3 = qdict_get_try_str(qdict, "arg3");
+
+    if (arg2) {
+        s = slirp_lookup(mon, arg1, arg2);
+        redir_str = arg3;
+    } else {
+        s = slirp_lookup(mon, NULL, NULL);
+        redir_str = arg1;
+    }
+    if (s) {
+        slirp_hostfwd(s, redir_str, 0);
+    }
+
+}
+
+int net_slirp_redir(const char *redir_str)
+{
+    struct slirp_config_str *config;
+
+    if (QTAILQ_EMPTY(&slirp_stacks)) {
+        config = qemu_malloc(sizeof(*config));
+        pstrcpy(config->str, sizeof(config->str), redir_str);
+        config->flags = SLIRP_CFG_HOSTFWD | SLIRP_CFG_LEGACY;
+        config->next = slirp_configs;
+        slirp_configs = config;
+        return 0;
+    }
+
+    return slirp_hostfwd(QTAILQ_FIRST(&slirp_stacks), redir_str, 1);
+}
+
+#ifndef _WIN32
+
+/* automatic user mode samba server configuration */
+static void slirp_smb_cleanup(SlirpState *s)
+{
+    char cmd[128];
+
+    if (s->smb_dir[0] != '\0') {
+        snprintf(cmd, sizeof(cmd), "rm -rf %s", s->smb_dir);
+        system(cmd);
+        s->smb_dir[0] = '\0';
+    }
+}
+
+static int slirp_smb(SlirpState* s, const char *exported_dir,
+                     struct in_addr vserver_addr)
+{
+    static int instance;
+    char smb_conf[128];
+    char smb_cmdline[128];
+    FILE *f;
+
+    snprintf(s->smb_dir, sizeof(s->smb_dir), "/tmp/qemu-smb.%ld-%d",
+             (long)getpid(), instance++);
+    if (mkdir(s->smb_dir, 0700) < 0) {
+        qemu_error("could not create samba server dir '%s'\n", s->smb_dir);
+        return -1;
+    }
+    snprintf(smb_conf, sizeof(smb_conf), "%s/%s", s->smb_dir, "smb.conf");
+
+    f = fopen(smb_conf, "w");
+    if (!f) {
+        slirp_smb_cleanup(s);
+        qemu_error("could not create samba server configuration file '%s'\n",
+                   smb_conf);
+        return -1;
+    }
+    fprintf(f,
+            "[global]\n"
+            "private dir=%s\n"
+            "smb ports=0\n"
+            "socket address=127.0.0.1\n"
+            "pid directory=%s\n"
+            "lock directory=%s\n"
+            "log file=%s/log.smbd\n"
+            "smb passwd file=%s/smbpasswd\n"
+            "security = share\n"
+            "[qemu]\n"
+            "path=%s\n"
+            "read only=no\n"
+            "guest ok=yes\n",
+            s->smb_dir,
+            s->smb_dir,
+            s->smb_dir,
+            s->smb_dir,
+            s->smb_dir,
+            exported_dir
+            );
+    fclose(f);
+
+    snprintf(smb_cmdline, sizeof(smb_cmdline), "%s -s %s",
+             SMBD_COMMAND, smb_conf);
+
+    if (slirp_add_exec(s->slirp, 0, smb_cmdline, &vserver_addr, 139) < 0) {
+        slirp_smb_cleanup(s);
+        qemu_error("conflicting/invalid smbserver address\n");
+        return -1;
+    }
+    return 0;
+}
+
+/* automatic user mode samba server configuration (legacy interface) */
+int net_slirp_smb(const char *exported_dir)
+{
+    struct in_addr vserver_addr = { .s_addr = 0 };
+
+    if (legacy_smb_export) {
+        fprintf(stderr, "-smb given twice\n");
+        return -1;
+    }
+    legacy_smb_export = exported_dir;
+    if (!QTAILQ_EMPTY(&slirp_stacks)) {
+        return slirp_smb(QTAILQ_FIRST(&slirp_stacks), exported_dir,
+                         vserver_addr);
+    }
+    return 0;
+}
+
+#endif /* !defined(_WIN32) */
+
+struct GuestFwd {
+    CharDriverState *hd;
+    struct in_addr server;
+    int port;
+    Slirp *slirp;
+};
+
+static int guestfwd_can_read(void *opaque)
+{
+    struct GuestFwd *fwd = opaque;
+    return slirp_socket_can_recv(fwd->slirp, fwd->server, fwd->port);
+}
+
+static void guestfwd_read(void *opaque, const uint8_t *buf, int size)
+{
+    struct GuestFwd *fwd = opaque;
+    slirp_socket_recv(fwd->slirp, fwd->server, fwd->port, buf, size);
+}
+
+static int slirp_guestfwd(SlirpState *s, const char *config_str,
+                          int legacy_format)
+{
+    struct in_addr server = { .s_addr = 0 };
+    struct GuestFwd *fwd;
+    const char *p;
+    char buf[128];
+    char *end;
+    int port;
+
+    p = config_str;
+    if (legacy_format) {
+        if (get_str_sep(buf, sizeof(buf), &p, ':') < 0) {
+            goto fail_syntax;
+        }
+    } else {
+        if (get_str_sep(buf, sizeof(buf), &p, ':') < 0) {
+            goto fail_syntax;
+        }
+        if (strcmp(buf, "tcp") && buf[0] != '\0') {
+            goto fail_syntax;
+        }
+        if (get_str_sep(buf, sizeof(buf), &p, ':') < 0) {
+            goto fail_syntax;
+        }
+        if (buf[0] != '\0' && !inet_aton(buf, &server)) {
+            goto fail_syntax;
+        }
+        if (get_str_sep(buf, sizeof(buf), &p, '-') < 0) {
+            goto fail_syntax;
+        }
+    }
+    port = strtol(buf, &end, 10);
+    if (*end != '\0' || port < 1 || port > 65535) {
+        goto fail_syntax;
+    }
+
+    fwd = qemu_malloc(sizeof(struct GuestFwd));
+    snprintf(buf, sizeof(buf), "guestfwd.tcp:%d", port);
+    fwd->hd = qemu_chr_open(buf, p, NULL);
+    if (!fwd->hd) {
+        qemu_error("could not open guest forwarding device '%s'\n", buf);
+        qemu_free(fwd);
+        return -1;
+    }
+
+    if (slirp_add_exec(s->slirp, 3, fwd->hd, &server, port) < 0) {
+        qemu_error("conflicting/invalid host:port in guest forwarding "
+                   "rule '%s'\n", config_str);
+        qemu_free(fwd);
+        return -1;
+    }
+    fwd->server = server;
+    fwd->port = port;
+    fwd->slirp = s->slirp;
+
+    qemu_chr_add_handlers(fwd->hd, guestfwd_can_read, guestfwd_read,
+                          NULL, fwd);
+    return 0;
+
+ fail_syntax:
+    qemu_error("invalid guest forwarding rule '%s'\n", config_str);
+    return -1;
+}
+
+void do_info_usernet(Monitor *mon)
+{
+    SlirpState *s;
+
+    QTAILQ_FOREACH(s, &slirp_stacks, entry) {
+        monitor_printf(mon, "VLAN %d (%s):\n", s->vc->vlan->id, s->vc->name);
+        slirp_connection_info(s->slirp, mon);
+    }
+}
+
+static int net_init_slirp_configs(const char *name, const char *value, void *opaque)
+{
+    struct slirp_config_str *config;
+
+    if (strcmp(name, "hostfwd") != 0 && strcmp(name, "guestfwd") != 0) {
+        return 0;
+    }
+
+    config = qemu_mallocz(sizeof(*config));
+
+    pstrcpy(config->str, sizeof(config->str), value);
+
+    if (!strcmp(name, "hostfwd")) {
+        config->flags = SLIRP_CFG_HOSTFWD;
+    }
+
+    config->next = slirp_configs;
+    slirp_configs = config;
+
+    return 0;
+}
+
+int net_init_slirp(QemuOpts *opts,
+                   Monitor *mon,
+                   const char *name,
+                   VLANState *vlan)
+{
+    struct slirp_config_str *config;
+    const char *vhost;
+    const char *vhostname;
+    const char *vdhcp_start;
+    const char *vnamesrv;
+    const char *tftp_export;
+    const char *bootfile;
+    const char *smb_export;
+    const char *vsmbsrv;
+    char *vnet = NULL;
+    int restricted = 0;
+    int ret;
+
+    vhost       = qemu_opt_get(opts, "host");
+    vhostname   = qemu_opt_get(opts, "hostname");
+    vdhcp_start = qemu_opt_get(opts, "dhcpstart");
+    vnamesrv    = qemu_opt_get(opts, "dns");
+    tftp_export = qemu_opt_get(opts, "tftp");
+    bootfile    = qemu_opt_get(opts, "bootfile");
+    smb_export  = qemu_opt_get(opts, "smb");
+    vsmbsrv     = qemu_opt_get(opts, "smbserver");
+
+    if (qemu_opt_get(opts, "ip")) {
+        const char *ip = qemu_opt_get(opts, "ip");
+        int l = strlen(ip) + strlen("/24") + 1;
+
+        vnet = qemu_malloc(l);
+
+        /* emulate legacy ip= parameter */
+        pstrcpy(vnet, l, ip);
+        pstrcat(vnet, l, "/24");
+    }
+
+    if (qemu_opt_get(opts, "net")) {
+        if (vnet) {
+            qemu_free(vnet);
+        }
+        vnet = qemu_strdup(qemu_opt_get(opts, "net"));
+    }
+
+    if (qemu_opt_get(opts, "restrict") &&
+        qemu_opt_get(opts, "restrict")[0] == 'y') {
+        restricted = 1;
+    }
+
+    qemu_opt_foreach(opts, net_init_slirp_configs, NULL, 0);
+
+    ret = net_slirp_init(vlan, "user", name, restricted, vnet, vhost,
+                         vhostname, tftp_export, bootfile, vdhcp_start,
+                         vnamesrv, smb_export, vsmbsrv);
+
+    while (slirp_configs) {
+        config = slirp_configs;
+        slirp_configs = config->next;
+        qemu_free(config);
+    }
+
+    if (ret != -1 && vlan) {
+        vlan->nb_host_devs++;
+    }
+
+    qemu_free(vnet);
+
+    return ret;
+}
+
+int net_slirp_parse_legacy(QemuOptsList *opts_list, const char *optarg, int *ret)
+{
+    if (strcmp(opts_list->name, "net") != 0 ||
+        strncmp(optarg, "channel,", strlen("channel,")) != 0) {
+        return 0;
+    }
+
+    /* handle legacy -net channel,port:chr */
+    optarg += strlen("channel,");
+
+    if (QTAILQ_EMPTY(&slirp_stacks)) {
+        struct slirp_config_str *config;
+
+        config = qemu_malloc(sizeof(*config));
+        pstrcpy(config->str, sizeof(config->str), optarg);
+        config->flags = SLIRP_CFG_LEGACY;
+        config->next = slirp_configs;
+        slirp_configs = config;
+        *ret = 0;
+    } else {
+        *ret = slirp_guestfwd(QTAILQ_FIRST(&slirp_stacks), optarg, 1);
+    }
+
+    return 1;
+}
+
diff --git a/net/slirp.h b/net/slirp.h
new file mode 100644
index 0000000000..c17de8ed47
--- /dev/null
+++ b/net/slirp.h
@@ -0,0 +1,51 @@
+/*
+ * QEMU System Emulator
+ *
+ * Copyright (c) 2003-2008 Fabrice Bellard
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#ifndef QEMU_NET_SLIRP_H
+#define QEMU_NET_SLIRP_H
+
+#include "qemu-common.h"
+#include "qdict.h"
+#include "qemu-option.h"
+
+#ifdef CONFIG_SLIRP
+
+int net_init_slirp(QemuOpts *opts,
+                   Monitor *mon,
+                   const char *name,
+                   VLANState *vlan);
+
+void net_slirp_hostfwd_add(Monitor *mon, const QDict *qdict);
+void net_slirp_hostfwd_remove(Monitor *mon, const QDict *qdict);
+
+int net_slirp_redir(const char *redir_str);
+
+int net_slirp_parse_legacy(QemuOptsList *opts_list, const char *optarg, int *ret);
+
+int net_slirp_smb(const char *exported_dir);
+
+void do_info_usernet(Monitor *mon);
+
+#endif
+
+#endif /* QEMU_NET_SLIRP_H */