slirp: generalize guestfwd with a callback based approach

Instead of calling into QEMU chardev directly, and mixing it with slirp_add_exec() handling, add a new function slirp_add_guestfwd() which takes a write callback. Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
qemu · Feb 7, 2019 · 44b4ff2 · 44b4ff2
1 parent aaa0c64
commit 44b4ff2
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Showing 7 changed files with 75 additions and 32 deletions.
diff --git a/net/slirp.c b/net/slirp.c
@@ -704,8 +704,8 @@ static int slirp_smb(SlirpState* s, const char *exported_dir,
              CONFIG_SMBD_COMMAND, s->smb_dir, smb_conf);
     g_free(smb_conf);
 
-    if (slirp_add_exec(s->slirp, NULL, smb_cmdline, &vserver_addr, 139) < 0 ||
-        slirp_add_exec(s->slirp, NULL, smb_cmdline, &vserver_addr, 445) < 0) {
+    if (slirp_add_exec(s->slirp, smb_cmdline, &vserver_addr, 139) < 0 ||
+        slirp_add_exec(s->slirp, smb_cmdline, &vserver_addr, 445) < 0) {
         slirp_smb_cleanup(s);
         g_free(smb_cmdline);
         error_setg(errp, "Conflicting/invalid smbserver address");
@@ -736,6 +736,11 @@ static void guestfwd_read(void *opaque, const uint8_t *buf, int size)
     slirp_socket_recv(fwd->slirp, fwd->server, fwd->port, buf, size);
 }
 
+static int guestfwd_write(const void *buf, size_t len, void *chr)
+{
+    return qemu_chr_fe_write_all(chr, buf, len);
+}
+
 static int slirp_guestfwd(SlirpState *s, const char *config_str, Error **errp)
 {
     struct in_addr server = { .s_addr = 0 };
@@ -769,7 +774,7 @@ static int slirp_guestfwd(SlirpState *s, const char *config_str, Error **errp)
     snprintf(buf, sizeof(buf), "guestfwd.tcp.%d", port);
 
     if ((strlen(p) > 4) && !strncmp(p, "cmd:", 4)) {
-        if (slirp_add_exec(s->slirp, NULL, &p[4], &server, port) < 0) {
+        if (slirp_add_exec(s->slirp, &p[4], &server, port) < 0) {
             error_setg(errp, "Conflicting/invalid host:port in guest "
                        "forwarding rule '%s'", config_str);
             return -1;
@@ -796,7 +801,8 @@ static int slirp_guestfwd(SlirpState *s, const char *config_str, Error **errp)
             return -1;
         }
 
-        if (slirp_add_exec(s->slirp, &fwd->hd, NULL, &server, port) < 0) {
+        if (slirp_add_guestfwd(s->slirp, guestfwd_write, &fwd->hd,
+                               &server, port) < 0) {
             error_setg(errp, "Conflicting/invalid host:port in guest "
                        "forwarding rule '%s'", config_str);
             g_free(fwd);

diff --git a/slirp/libslirp.h b/slirp/libslirp.h
@@ -5,6 +5,8 @@
 
 typedef struct Slirp Slirp;
 
+typedef int (*SlirpWriteCb)(const void *buf, size_t len, void *opaque);
+
 /*
  * Callbacks from slirp
  *
@@ -45,7 +47,9 @@ int slirp_add_hostfwd(Slirp *slirp, int is_udp,
                       struct in_addr guest_addr, int guest_port);
 int slirp_remove_hostfwd(Slirp *slirp, int is_udp,
                          struct in_addr host_addr, int host_port);
-int slirp_add_exec(Slirp *slirp, void *chardev, const char *cmdline,
+int slirp_add_exec(Slirp *slirp, const char *cmdline,
+                   struct in_addr *guest_addr, int guest_port);
+int slirp_add_guestfwd(Slirp *slirp, SlirpWriteCb write_cb, void *opaque,
                    struct in_addr *guest_addr, int guest_port);
 
 char *slirp_connection_info(Slirp *slirp);

diff --git a/slirp/misc.c b/slirp/misc.c
@@ -32,24 +32,33 @@ remque(void *a)
   element->qh_rlink = NULL;
 }
 
-int add_exec(struct gfwd_list **ex_ptr, void *chardev, const char *cmdline,
+struct gfwd_list *
+add_guestfwd(struct gfwd_list **ex_ptr,
+             SlirpWriteCb write_cb, void *opaque,
              struct in_addr addr, int port)
 {
-	struct gfwd_list *tmp_ptr;
-
-	tmp_ptr = *ex_ptr;
-	*ex_ptr = g_new0(struct gfwd_list, 1);
-	(*ex_ptr)->ex_fport = port;
-	(*ex_ptr)->ex_addr = addr;
-	if (chardev) {
-		(*ex_ptr)->ex_chardev = chardev;
-	} else {
-		(*ex_ptr)->ex_exec = g_strdup(cmdline);
-	}
-	(*ex_ptr)->ex_next = tmp_ptr;
-	return 0;
+    struct gfwd_list *f = g_new0(struct gfwd_list, 1);
+
+    f->write_cb = write_cb;
+    f->opaque = opaque;
+    f->ex_fport = port;
+    f->ex_addr = addr;
+    f->ex_next = *ex_ptr;
+    *ex_ptr = f;
+
+    return f;
 }
 
+struct gfwd_list *
+add_exec(struct gfwd_list **ex_ptr, const char *cmdline,
+         struct in_addr addr, int port)
+{
+    struct gfwd_list *f = add_guestfwd(ex_ptr, NULL, NULL, addr, port);
+
+    f->ex_exec = g_strdup(cmdline);
+
+    return f;
+}
 
 static int
 slirp_socketpair_with_oob(int sv[2])

diff --git a/slirp/misc.h b/slirp/misc.h
@@ -8,8 +8,11 @@
 #ifndef MISC_H
 #define MISC_H
 
+#include "libslirp.h"
+
 struct gfwd_list {
-	void *ex_chardev;
+	SlirpWriteCb write_cb;
+	void *opaque;
 	struct in_addr ex_addr;		/* Server address */
 	int ex_fport;                   /* Port to telnet to */
 	char *ex_exec;                  /* Command line of what to exec */
@@ -51,7 +54,15 @@ struct slirp_quehead {
 
 void slirp_insque(void *, void *);
 void slirp_remque(void *);
-int add_exec(struct gfwd_list **, void *, const char *, struct in_addr, int);
 int fork_exec(struct socket *so, const char *ex);
 
+struct gfwd_list *
+add_guestfwd(struct gfwd_list **ex_ptr,
+             SlirpWriteCb write_cb, void *opaque,
+             struct in_addr addr, int port);
+
+struct gfwd_list *
+add_exec(struct gfwd_list **ex_ptr, const char *cmdline,
+         struct in_addr addr, int port);
+
 #endif
diff --git a/slirp/slirp.c b/slirp/slirp.c
@@ -25,7 +25,6 @@
 #include "qemu-common.h"
 #include "qemu/timer.h"
 #include "qemu/error-report.h"
-#include "chardev/char-fe.h"
 #include "migration/register.h"
 #include "slirp.h"
 #include "hw/hw.h"
@@ -1068,23 +1067,35 @@ check_guestfwd(Slirp *slirp, struct in_addr *guest_addr, int guest_port)
     return true;
 }
 
-int slirp_add_exec(Slirp *slirp, void *chardev, const char *cmdline,
+int slirp_add_exec(Slirp *slirp, const char *cmdline,
                    struct in_addr *guest_addr, int guest_port)
 {
     if (!check_guestfwd(slirp, guest_addr, guest_port)) {
         return -1;
     }
 
-    return add_exec(&slirp->guestfwd_list, chardev, cmdline, *guest_addr,
-                    htons(guest_port));
+    add_exec(&slirp->guestfwd_list, cmdline, *guest_addr, htons(guest_port));
+    return 0;
+}
+
+int slirp_add_guestfwd(Slirp *slirp, SlirpWriteCb write_cb, void *opaque,
+                       struct in_addr *guest_addr, int guest_port)
+{
+    if (!check_guestfwd(slirp, guest_addr, guest_port)) {
+        return -1;
+    }
+
+    add_guestfwd(&slirp->guestfwd_list, write_cb, opaque,
+                 *guest_addr, htons(guest_port));
+    return 0;
 }
 
 ssize_t slirp_send(struct socket *so, const void *buf, size_t len, int flags)
 {
-    if (so->s == -1 && so->chardev) {
+    if (so->s == -1 && so->guestfwd) {
         /* XXX this blocks entire thread. Rewrite to use
          * qemu_chr_fe_write and background I/O callbacks */
-        qemu_chr_fe_write_all(so->chardev, buf, len);
+        so->guestfwd->write_cb(buf, len, so->guestfwd->opaque);
         return len;
     }
 
@@ -1449,7 +1460,7 @@ static void slirp_state_save(QEMUFile *f, void *opaque)
     struct gfwd_list *ex_ptr;
 
     for (ex_ptr = slirp->guestfwd_list; ex_ptr; ex_ptr = ex_ptr->ex_next)
-        if (ex_ptr->ex_chardev) {
+        if (ex_ptr->write_cb) {
             struct socket *so;
             so = slirp_find_ctl_socket(slirp, ex_ptr->ex_addr,
                                        ntohs(ex_ptr->ex_fport));
@@ -1484,7 +1495,7 @@ static int slirp_state_load(QEMUFile *f, void *opaque, int version_id)
             return -EINVAL;
         }
         for (ex_ptr = slirp->guestfwd_list; ex_ptr; ex_ptr = ex_ptr->ex_next) {
-            if (ex_ptr->ex_chardev &&
+            if (ex_ptr->write_cb &&
                 so->so_faddr.s_addr == ex_ptr->ex_addr.s_addr &&
                 so->so_fport == ex_ptr->ex_fport) {
                 break;

diff --git a/slirp/socket.h b/slirp/socket.h
@@ -8,6 +8,8 @@
 #ifndef SLIRP_SOCKET_H
 #define SLIRP_SOCKET_H
 
+#include "misc.h"
+
 #define SO_EXPIRE 240000
 #define SO_EXPIREFAST 10000
 
@@ -25,6 +27,7 @@ struct socket {
   struct socket *so_next,*so_prev;      /* For a linked list of sockets */
 
   int s;                           /* The actual socket */
+  struct gfwd_list *guestfwd;
 
   int pollfds_idx;                 /* GPollFD GArray index */
 
@@ -67,7 +70,6 @@ struct socket {
 
   struct sbuf so_rcv;		/* Receive buffer */
   struct sbuf so_snd;		/* Send buffer */
-  void * chardev;
 };
 
 

diff --git a/slirp/tcp_subr.c b/slirp/tcp_subr.c
@@ -964,9 +964,9 @@ int tcp_ctl(struct socket *so)
         for (ex_ptr = slirp->guestfwd_list; ex_ptr; ex_ptr = ex_ptr->ex_next) {
             if (ex_ptr->ex_fport == so->so_fport &&
                 so->so_faddr.s_addr == ex_ptr->ex_addr.s_addr) {
-                if (ex_ptr->ex_chardev) {
+                if (ex_ptr->write_cb) {
                     so->s = -1;
-                    so->chardev = ex_ptr->ex_chardev;
+                    so->guestfwd = ex_ptr;
                     return 1;
                 }
                 DEBUG_MISC(" executing %s", ex_ptr->ex_exec);