xref: /openbmc/qemu/net/slirp.c (revision 1fd6bb44) 
1 /*
2  * QEMU System Emulator
3  *
4  * Copyright (c) 2003-2008 Fabrice Bellard
5  *
6  * Permission is hereby granted, free of charge, to any person obtaining a copy
7  * of this software and associated documentation files (the "Software"), to deal
8  * in the Software without restriction, including without limitation the rights
9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10  * copies of the Software, and to permit persons to whom the Software is
11  * furnished to do so, subject to the following conditions:
12  *
13  * The above copyright notice and this permission notice shall be included in
14  * all copies or substantial portions of the Software.
15  *
16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22  * THE SOFTWARE.
23  */
24 #include "net/slirp.h"
25 
26 #include "config-host.h"
27 
28 #ifndef _WIN32
29 #include <pwd.h>
30 #include <sys/wait.h>
31 #endif
32 #include "net/net.h"
33 #include "clients.h"
34 #include "hub.h"
35 #include "monitor/monitor.h"
36 #include "qemu/sockets.h"
37 #include "slirp/libslirp.h"
38 #include "char/char.h"
39 
40 static int get_str_sep(char *buf, int buf_size, const char **pp, int sep)
41 {
42     const char *p, *p1;
43     int len;
44     p = *pp;
45     p1 = strchr(p, sep);
46     if (!p1)
47         return -1;
48     len = p1 - p;
49     p1++;
50     if (buf_size > 0) {
51         if (len > buf_size - 1)
52             len = buf_size - 1;
53         memcpy(buf, p, len);
54         buf[len] = '\0';
55     }
56     *pp = p1;
57     return 0;
58 }
59 
60 /* slirp network adapter */
61 
62 #define SLIRP_CFG_HOSTFWD 1
63 #define SLIRP_CFG_LEGACY  2
64 
65 struct slirp_config_str {
66     struct slirp_config_str *next;
67     int flags;
68     char str[1024];
69     int legacy_format;
70 };
71 
72 typedef struct SlirpState {
73     NetClientState nc;
74     QTAILQ_ENTRY(SlirpState) entry;
75     Slirp *slirp;
76 #ifndef _WIN32
77     char smb_dir[128];
78 #endif
79 } SlirpState;
80 
81 static struct slirp_config_str *slirp_configs;
82 const char *legacy_tftp_prefix;
83 const char *legacy_bootp_filename;
84 static QTAILQ_HEAD(slirp_stacks, SlirpState) slirp_stacks =
85     QTAILQ_HEAD_INITIALIZER(slirp_stacks);
86 
87 static int slirp_hostfwd(SlirpState *s, const char *redir_str,
88                          int legacy_format);
89 static int slirp_guestfwd(SlirpState *s, const char *config_str,
90                           int legacy_format);
91 
92 #ifndef _WIN32
93 static const char *legacy_smb_export;
94 
95 static int slirp_smb(SlirpState *s, const char *exported_dir,
96                      struct in_addr vserver_addr);
97 static void slirp_smb_cleanup(SlirpState *s);
98 #else
99 static inline void slirp_smb_cleanup(SlirpState *s) { }
100 #endif
101 
102 void slirp_output(void *opaque, const uint8_t *pkt, int pkt_len)
103 {
104     SlirpState *s = opaque;
105 
106     qemu_send_packet(&s->nc, pkt, pkt_len);
107 }
108 
109 static ssize_t net_slirp_receive(NetClientState *nc, const uint8_t *buf, size_t size)
110 {
111     SlirpState *s = DO_UPCAST(SlirpState, nc, nc);
112 
113     slirp_input(s->slirp, buf, size);
114 
115     return size;
116 }
117 
118 static void net_slirp_cleanup(NetClientState *nc)
119 {
120     SlirpState *s = DO_UPCAST(SlirpState, nc, nc);
121 
122     slirp_cleanup(s->slirp);
123     slirp_smb_cleanup(s);
124     QTAILQ_REMOVE(&slirp_stacks, s, entry);
125 }
126 
127 static NetClientInfo net_slirp_info = {
128     .type = NET_CLIENT_OPTIONS_KIND_USER,
129     .size = sizeof(SlirpState),
130     .receive = net_slirp_receive,
131     .cleanup = net_slirp_cleanup,
132 };
133 
134 static int net_slirp_init(NetClientState *peer, const char *model,
135                           const char *name, int restricted,
136                           const char *vnetwork, const char *vhost,
137                           const char *vhostname, const char *tftp_export,
138                           const char *bootfile, const char *vdhcp_start,
139                           const char *vnameserver, const char *smb_export,
140                           const char *vsmbserver, const char **dnssearch)
141 {
142     /* default settings according to historic slirp */
143     struct in_addr net  = { .s_addr = htonl(0x0a000200) }; /* 10.0.2.0 */
144     struct in_addr mask = { .s_addr = htonl(0xffffff00) }; /* 255.255.255.0 */
145     struct in_addr host = { .s_addr = htonl(0x0a000202) }; /* 10.0.2.2 */
146     struct in_addr dhcp = { .s_addr = htonl(0x0a00020f) }; /* 10.0.2.15 */
147     struct in_addr dns  = { .s_addr = htonl(0x0a000203) }; /* 10.0.2.3 */
148 #ifndef _WIN32
149     struct in_addr smbsrv = { .s_addr = 0 };
150 #endif
151     NetClientState *nc;
152     SlirpState *s;
153     char buf[20];
154     uint32_t addr;
155     int shift;
156     char *end;
157     struct slirp_config_str *config;
158 
159     if (!tftp_export) {
160         tftp_export = legacy_tftp_prefix;
161     }
162     if (!bootfile) {
163         bootfile = legacy_bootp_filename;
164     }
165 
166     if (vnetwork) {
167         if (get_str_sep(buf, sizeof(buf), &vnetwork, '/') < 0) {
168             if (!inet_aton(vnetwork, &net)) {
169                 return -1;
170             }
171             addr = ntohl(net.s_addr);
172             if (!(addr & 0x80000000)) {
173                 mask.s_addr = htonl(0xff000000); /* class A */
174             } else if ((addr & 0xfff00000) == 0xac100000) {
175                 mask.s_addr = htonl(0xfff00000); /* priv. 172.16.0.0/12 */
176             } else if ((addr & 0xc0000000) == 0x80000000) {
177                 mask.s_addr = htonl(0xffff0000); /* class B */
178             } else if ((addr & 0xffff0000) == 0xc0a80000) {
179                 mask.s_addr = htonl(0xffff0000); /* priv. 192.168.0.0/16 */
180             } else if ((addr & 0xffff0000) == 0xc6120000) {
181                 mask.s_addr = htonl(0xfffe0000); /* tests 198.18.0.0/15 */
182             } else if ((addr & 0xe0000000) == 0xe0000000) {
183                 mask.s_addr = htonl(0xffffff00); /* class C */
184             } else {
185                 mask.s_addr = htonl(0xfffffff0); /* multicast/reserved */
186             }
187         } else {
188             if (!inet_aton(buf, &net)) {
189                 return -1;
190             }
191             shift = strtol(vnetwork, &end, 10);
192             if (*end != '\0') {
193                 if (!inet_aton(vnetwork, &mask)) {
194                     return -1;
195                 }
196             } else if (shift < 4 || shift > 32) {
197                 return -1;
198             } else {
199                 mask.s_addr = htonl(0xffffffff << (32 - shift));
200             }
201         }
202         net.s_addr &= mask.s_addr;
203         host.s_addr = net.s_addr | (htonl(0x0202) & ~mask.s_addr);
204         dhcp.s_addr = net.s_addr | (htonl(0x020f) & ~mask.s_addr);
205         dns.s_addr  = net.s_addr | (htonl(0x0203) & ~mask.s_addr);
206     }
207 
208     if (vhost && !inet_aton(vhost, &host)) {
209         return -1;
210     }
211     if ((host.s_addr & mask.s_addr) != net.s_addr) {
212         return -1;
213     }
214 
215     if (vdhcp_start && !inet_aton(vdhcp_start, &dhcp)) {
216         return -1;
217     }
218     if ((dhcp.s_addr & mask.s_addr) != net.s_addr ||
219         dhcp.s_addr == host.s_addr || dhcp.s_addr == dns.s_addr) {
220         return -1;
221     }
222 
223     if (vnameserver && !inet_aton(vnameserver, &dns)) {
224         return -1;
225     }
226     if ((dns.s_addr & mask.s_addr) != net.s_addr ||
227         dns.s_addr == host.s_addr) {
228         return -1;
229     }
230 
231 #ifndef _WIN32
232     if (vsmbserver && !inet_aton(vsmbserver, &smbsrv)) {
233         return -1;
234     }
235 #endif
236 
237     nc = qemu_new_net_client(&net_slirp_info, peer, model, name);
238 
239     snprintf(nc->info_str, sizeof(nc->info_str),
240              "net=%s,restrict=%s", inet_ntoa(net),
241              restricted ? "on" : "off");
242 
243     s = DO_UPCAST(SlirpState, nc, nc);
244 
245     s->slirp = slirp_init(restricted, net, mask, host, vhostname,
246                           tftp_export, bootfile, dhcp, dns, dnssearch, s);
247     QTAILQ_INSERT_TAIL(&slirp_stacks, s, entry);
248 
249     for (config = slirp_configs; config; config = config->next) {
250         if (config->flags & SLIRP_CFG_HOSTFWD) {
251             if (slirp_hostfwd(s, config->str,
252                               config->flags & SLIRP_CFG_LEGACY) < 0)
253                 goto error;
254         } else {
255             if (slirp_guestfwd(s, config->str,
256                                config->flags & SLIRP_CFG_LEGACY) < 0)
257                 goto error;
258         }
259     }
260 #ifndef _WIN32
261     if (!smb_export) {
262         smb_export = legacy_smb_export;
263     }
264     if (smb_export) {
265         if (slirp_smb(s, smb_export, smbsrv) < 0)
266             goto error;
267     }
268 #endif
269 
270     return 0;
271 
272 error:
273     qemu_del_net_client(nc);
274     return -1;
275 }
276 
277 static SlirpState *slirp_lookup(Monitor *mon, const char *vlan,
278                                 const char *stack)
279 {
280 
281     if (vlan) {
282         NetClientState *nc;
283         nc = net_hub_find_client_by_name(strtol(vlan, NULL, 0), stack);
284         if (!nc) {
285             return NULL;
286         }
287         if (strcmp(nc->model, "user")) {
288             monitor_printf(mon, "invalid device specified\n");
289             return NULL;
290         }
291         return DO_UPCAST(SlirpState, nc, nc);
292     } else {
293         if (QTAILQ_EMPTY(&slirp_stacks)) {
294             monitor_printf(mon, "user mode network stack not in use\n");
295             return NULL;
296         }
297         return QTAILQ_FIRST(&slirp_stacks);
298     }
299 }
300 
301 void net_slirp_hostfwd_remove(Monitor *mon, const QDict *qdict)
302 {
303     struct in_addr host_addr = { .s_addr = INADDR_ANY };
304     int host_port;
305     char buf[256];
306     const char *src_str, *p;
307     SlirpState *s;
308     int is_udp = 0;
309     int err;
310     const char *arg1 = qdict_get_str(qdict, "arg1");
311     const char *arg2 = qdict_get_try_str(qdict, "arg2");
312     const char *arg3 = qdict_get_try_str(qdict, "arg3");
313 
314     if (arg2) {
315         s = slirp_lookup(mon, arg1, arg2);
316         src_str = arg3;
317     } else {
318         s = slirp_lookup(mon, NULL, NULL);
319         src_str = arg1;
320     }
321     if (!s) {
322         return;
323     }
324 
325     p = src_str;
326     if (!p || get_str_sep(buf, sizeof(buf), &p, ':') < 0) {
327         goto fail_syntax;
328     }
329 
330     if (!strcmp(buf, "tcp") || buf[0] == '\0') {
331         is_udp = 0;
332     } else if (!strcmp(buf, "udp")) {
333         is_udp = 1;
334     } else {
335         goto fail_syntax;
336     }
337 
338     if (get_str_sep(buf, sizeof(buf), &p, ':') < 0) {
339         goto fail_syntax;
340     }
341     if (buf[0] != '\0' && !inet_aton(buf, &host_addr)) {
342         goto fail_syntax;
343     }
344 
345     host_port = atoi(p);
346 
347     err = slirp_remove_hostfwd(QTAILQ_FIRST(&slirp_stacks)->slirp, is_udp,
348                                host_addr, host_port);
349 
350     monitor_printf(mon, "host forwarding rule for %s %s\n", src_str,
351                    err ? "not found" : "removed");
352     return;
353 
354  fail_syntax:
355     monitor_printf(mon, "invalid format\n");
356 }
357 
358 static int slirp_hostfwd(SlirpState *s, const char *redir_str,
359                          int legacy_format)
360 {
361     struct in_addr host_addr = { .s_addr = INADDR_ANY };
362     struct in_addr guest_addr = { .s_addr = 0 };
363     int host_port, guest_port;
364     const char *p;
365     char buf[256];
366     int is_udp;
367     char *end;
368 
369     p = redir_str;
370     if (!p || get_str_sep(buf, sizeof(buf), &p, ':') < 0) {
371         goto fail_syntax;
372     }
373     if (!strcmp(buf, "tcp") || buf[0] == '\0') {
374         is_udp = 0;
375     } else if (!strcmp(buf, "udp")) {
376         is_udp = 1;
377     } else {
378         goto fail_syntax;
379     }
380 
381     if (!legacy_format) {
382         if (get_str_sep(buf, sizeof(buf), &p, ':') < 0) {
383             goto fail_syntax;
384         }
385         if (buf[0] != '\0' && !inet_aton(buf, &host_addr)) {
386             goto fail_syntax;
387         }
388     }
389 
390     if (get_str_sep(buf, sizeof(buf), &p, legacy_format ? ':' : '-') < 0) {
391         goto fail_syntax;
392     }
393     host_port = strtol(buf, &end, 0);
394     if (*end != '\0' || host_port < 1 || host_port > 65535) {
395         goto fail_syntax;
396     }
397 
398     if (get_str_sep(buf, sizeof(buf), &p, ':') < 0) {
399         goto fail_syntax;
400     }
401     if (buf[0] != '\0' && !inet_aton(buf, &guest_addr)) {
402         goto fail_syntax;
403     }
404 
405     guest_port = strtol(p, &end, 0);
406     if (*end != '\0' || guest_port < 1 || guest_port > 65535) {
407         goto fail_syntax;
408     }
409 
410     if (slirp_add_hostfwd(s->slirp, is_udp, host_addr, host_port, guest_addr,
411                           guest_port) < 0) {
412         error_report("could not set up host forwarding rule '%s'",
413                      redir_str);
414         return -1;
415     }
416     return 0;
417 
418  fail_syntax:
419     error_report("invalid host forwarding rule '%s'", redir_str);
420     return -1;
421 }
422 
423 void net_slirp_hostfwd_add(Monitor *mon, const QDict *qdict)
424 {
425     const char *redir_str;
426     SlirpState *s;
427     const char *arg1 = qdict_get_str(qdict, "arg1");
428     const char *arg2 = qdict_get_try_str(qdict, "arg2");
429     const char *arg3 = qdict_get_try_str(qdict, "arg3");
430 
431     if (arg2) {
432         s = slirp_lookup(mon, arg1, arg2);
433         redir_str = arg3;
434     } else {
435         s = slirp_lookup(mon, NULL, NULL);
436         redir_str = arg1;
437     }
438     if (s) {
439         slirp_hostfwd(s, redir_str, 0);
440     }
441 
442 }
443 
444 int net_slirp_redir(const char *redir_str)
445 {
446     struct slirp_config_str *config;
447 
448     if (QTAILQ_EMPTY(&slirp_stacks)) {
449         config = g_malloc(sizeof(*config));
450         pstrcpy(config->str, sizeof(config->str), redir_str);
451         config->flags = SLIRP_CFG_HOSTFWD | SLIRP_CFG_LEGACY;
452         config->next = slirp_configs;
453         slirp_configs = config;
454         return 0;
455     }
456 
457     return slirp_hostfwd(QTAILQ_FIRST(&slirp_stacks), redir_str, 1);
458 }
459 
460 #ifndef _WIN32
461 
462 /* automatic user mode samba server configuration */
463 static void slirp_smb_cleanup(SlirpState *s)
464 {
465     char cmd[128];
466     int ret;
467 
468     if (s->smb_dir[0] != '\0') {
469         snprintf(cmd, sizeof(cmd), "rm -rf %s", s->smb_dir);
470         ret = system(cmd);
471         if (ret == -1 || !WIFEXITED(ret)) {
472             error_report("'%s' failed.", cmd);
473         } else if (WEXITSTATUS(ret)) {
474             error_report("'%s' failed. Error code: %d",
475                          cmd, WEXITSTATUS(ret));
476         }
477         s->smb_dir[0] = '\0';
478     }
479 }
480 
481 static int slirp_smb(SlirpState* s, const char *exported_dir,
482                      struct in_addr vserver_addr)
483 {
484     static int instance;
485     char smb_conf[128];
486     char smb_cmdline[128];
487     struct passwd *passwd;
488     FILE *f;
489 
490     passwd = getpwuid(geteuid());
491     if (!passwd) {
492         error_report("failed to retrieve user name");
493         return -1;
494     }
495 
496     if (access(CONFIG_SMBD_COMMAND, F_OK)) {
497         error_report("could not find '%s', please install it",
498                      CONFIG_SMBD_COMMAND);
499         return -1;
500     }
501 
502     if (access(exported_dir, R_OK | X_OK)) {
503         error_report("error accessing shared directory '%s': %s",
504                      exported_dir, strerror(errno));
505         return -1;
506     }
507 
508     snprintf(s->smb_dir, sizeof(s->smb_dir), "/tmp/qemu-smb.%ld-%d",
509              (long)getpid(), instance++);
510     if (mkdir(s->smb_dir, 0700) < 0) {
511         error_report("could not create samba server dir '%s'", s->smb_dir);
512         return -1;
513     }
514     snprintf(smb_conf, sizeof(smb_conf), "%s/%s", s->smb_dir, "smb.conf");
515 
516     f = fopen(smb_conf, "w");
517     if (!f) {
518         slirp_smb_cleanup(s);
519         error_report("could not create samba server configuration file '%s'",
520                      smb_conf);
521         return -1;
522     }
523     fprintf(f,
524             "[global]\n"
525             "private dir=%s\n"
526             "socket address=127.0.0.1\n"
527             "pid directory=%s\n"
528             "lock directory=%s\n"
529             "state directory=%s\n"
530             "log file=%s/log.smbd\n"
531             "smb passwd file=%s/smbpasswd\n"
532             "security = share\n"
533             "[qemu]\n"
534             "path=%s\n"
535             "read only=no\n"
536             "guest ok=yes\n"
537             "force user=%s\n",
538             s->smb_dir,
539             s->smb_dir,
540             s->smb_dir,
541             s->smb_dir,
542             s->smb_dir,
543             s->smb_dir,
544             exported_dir,
545             passwd->pw_name
546             );
547     fclose(f);
548 
549     snprintf(smb_cmdline, sizeof(smb_cmdline), "%s -s %s",
550              CONFIG_SMBD_COMMAND, smb_conf);
551 
552     if (slirp_add_exec(s->slirp, 0, smb_cmdline, &vserver_addr, 139) < 0) {
553         slirp_smb_cleanup(s);
554         error_report("conflicting/invalid smbserver address");
555         return -1;
556     }
557     return 0;
558 }
559 
560 /* automatic user mode samba server configuration (legacy interface) */
561 int net_slirp_smb(const char *exported_dir)
562 {
563     struct in_addr vserver_addr = { .s_addr = 0 };
564 
565     if (legacy_smb_export) {
566         fprintf(stderr, "-smb given twice\n");
567         return -1;
568     }
569     legacy_smb_export = exported_dir;
570     if (!QTAILQ_EMPTY(&slirp_stacks)) {
571         return slirp_smb(QTAILQ_FIRST(&slirp_stacks), exported_dir,
572                          vserver_addr);
573     }
574     return 0;
575 }
576 
577 #endif /* !defined(_WIN32) */
578 
579 struct GuestFwd {
580     CharDriverState *hd;
581     struct in_addr server;
582     int port;
583     Slirp *slirp;
584 };
585 
586 static int guestfwd_can_read(void *opaque)
587 {
588     struct GuestFwd *fwd = opaque;
589     return slirp_socket_can_recv(fwd->slirp, fwd->server, fwd->port);
590 }
591 
592 static void guestfwd_read(void *opaque, const uint8_t *buf, int size)
593 {
594     struct GuestFwd *fwd = opaque;
595     slirp_socket_recv(fwd->slirp, fwd->server, fwd->port, buf, size);
596 }
597 
598 static int slirp_guestfwd(SlirpState *s, const char *config_str,
599                           int legacy_format)
600 {
601     struct in_addr server = { .s_addr = 0 };
602     struct GuestFwd *fwd;
603     const char *p;
604     char buf[128];
605     char *end;
606     int port;
607 
608     p = config_str;
609     if (legacy_format) {
610         if (get_str_sep(buf, sizeof(buf), &p, ':') < 0) {
611             goto fail_syntax;
612         }
613     } else {
614         if (get_str_sep(buf, sizeof(buf), &p, ':') < 0) {
615             goto fail_syntax;
616         }
617         if (strcmp(buf, "tcp") && buf[0] != '\0') {
618             goto fail_syntax;
619         }
620         if (get_str_sep(buf, sizeof(buf), &p, ':') < 0) {
621             goto fail_syntax;
622         }
623         if (buf[0] != '\0' && !inet_aton(buf, &server)) {
624             goto fail_syntax;
625         }
626         if (get_str_sep(buf, sizeof(buf), &p, '-') < 0) {
627             goto fail_syntax;
628         }
629     }
630     port = strtol(buf, &end, 10);
631     if (*end != '\0' || port < 1 || port > 65535) {
632         goto fail_syntax;
633     }
634 
635     fwd = g_malloc(sizeof(struct GuestFwd));
636     snprintf(buf, sizeof(buf), "guestfwd.tcp.%d", port);
637 
638     if ((strlen(p) > 4) && !strncmp(p, "cmd:", 4)) {
639         if (slirp_add_exec(s->slirp, 0, &p[4], &server, port) < 0) {
640             error_report("conflicting/invalid host:port in guest forwarding "
641                          "rule '%s'", config_str);
642             g_free(fwd);
643             return -1;
644         }
645     } else {
646         fwd->hd = qemu_chr_new(buf, p, NULL);
647         if (!fwd->hd) {
648             error_report("could not open guest forwarding device '%s'", buf);
649             g_free(fwd);
650             return -1;
651         }
652 
653         if (slirp_add_exec(s->slirp, 3, fwd->hd, &server, port) < 0) {
654             error_report("conflicting/invalid host:port in guest forwarding "
655                          "rule '%s'", config_str);
656             g_free(fwd);
657             return -1;
658         }
659         fwd->server = server;
660         fwd->port = port;
661         fwd->slirp = s->slirp;
662 
663         qemu_chr_fe_claim_no_fail(fwd->hd);
664         qemu_chr_add_handlers(fwd->hd, guestfwd_can_read, guestfwd_read,
665                               NULL, fwd);
666     }
667     return 0;
668 
669  fail_syntax:
670     error_report("invalid guest forwarding rule '%s'", config_str);
671     return -1;
672 }
673 
674 void do_info_usernet(Monitor *mon, const QDict *qdict)
675 {
676     SlirpState *s;
677 
678     QTAILQ_FOREACH(s, &slirp_stacks, entry) {
679         int id;
680         bool got_vlan_id = net_hub_id_for_client(&s->nc, &id) == 0;
681         monitor_printf(mon, "VLAN %d (%s):\n",
682                        got_vlan_id ? id : -1,
683                        s->nc.name);
684         slirp_connection_info(s->slirp, mon);
685     }
686 }
687 
688 static void
689 net_init_slirp_configs(const StringList *fwd, int flags)
690 {
691     while (fwd) {
692         struct slirp_config_str *config;
693 
694         config = g_malloc0(sizeof(*config));
695         pstrcpy(config->str, sizeof(config->str), fwd->value->str);
696         config->flags = flags;
697         config->next = slirp_configs;
698         slirp_configs = config;
699 
700         fwd = fwd->next;
701     }
702 }
703 
704 static const char **slirp_dnssearch(const StringList *dnsname)
705 {
706     const StringList *c = dnsname;
707     size_t i = 0, num_opts = 0;
708     const char **ret;
709 
710     while (c) {
711         num_opts++;
712         c = c->next;
713     }
714 
715     if (num_opts == 0) {
716         return NULL;
717     }
718 
719     ret = g_malloc((num_opts + 1) * sizeof(*ret));
720     c = dnsname;
721     while (c) {
722         ret[i++] = c->value->str;
723         c = c->next;
724     }
725     ret[i] = NULL;
726     return ret;
727 }
728 
729 int net_init_slirp(const NetClientOptions *opts, const char *name,
730                    NetClientState *peer)
731 {
732     struct slirp_config_str *config;
733     char *vnet;
734     int ret;
735     const NetdevUserOptions *user;
736     const char **dnssearch;
737 
738     assert(opts->kind == NET_CLIENT_OPTIONS_KIND_USER);
739     user = opts->user;
740 
741     vnet = user->has_net ? g_strdup(user->net) :
742            user->has_ip  ? g_strdup_printf("%s/24", user->ip) :
743            NULL;
744 
745     dnssearch = slirp_dnssearch(user->dnssearch);
746 
747     /* all optional fields are initialized to "all bits zero" */
748 
749     net_init_slirp_configs(user->hostfwd, SLIRP_CFG_HOSTFWD);
750     net_init_slirp_configs(user->guestfwd, 0);
751 
752     ret = net_slirp_init(peer, "user", name, user->q_restrict, vnet,
753                          user->host, user->hostname, user->tftp,
754                          user->bootfile, user->dhcpstart, user->dns, user->smb,
755                          user->smbserver, dnssearch);
756 
757     while (slirp_configs) {
758         config = slirp_configs;
759         slirp_configs = config->next;
760         g_free(config);
761     }
762 
763     g_free(vnet);
764     g_free(dnssearch);
765 
766     return ret;
767 }
768 
769 int net_slirp_parse_legacy(QemuOptsList *opts_list, const char *optarg, int *ret)
770 {
771     if (strcmp(opts_list->name, "net") != 0 ||
772         strncmp(optarg, "channel,", strlen("channel,")) != 0) {
773         return 0;
774     }
775 
776     /* handle legacy -net channel,port:chr */
777     optarg += strlen("channel,");
778 
779     if (QTAILQ_EMPTY(&slirp_stacks)) {
780         struct slirp_config_str *config;
781 
782         config = g_malloc(sizeof(*config));
783         pstrcpy(config->str, sizeof(config->str), optarg);
784         config->flags = SLIRP_CFG_LEGACY;
785         config->next = slirp_configs;
786         slirp_configs = config;
787         *ret = 0;
788     } else {
789         *ret = slirp_guestfwd(QTAILQ_FIRST(&slirp_stacks), optarg, 1);
790     }
791 
792     return 1;
793 }
794 
795