X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/preload-hacks/blobdiff_plain/6ec34720b0d2effe661c9dd4da2ef47a4e5030e3..54ef96bf3ee587718974b094f64fbff1301cc997:/noip.c

diff --git a/noip.c b/noip.c
index 0063ee9..345f325 100644
--- a/noip.c
+++ b/noip.c
@@ -57,9 +57,19 @@
 #include <ifaddrs.h>
 #include <netdb.h>
 
+#ifndef SUN_LEN
+#  define SUN_LEN (sun) \
+	(strlen((sun)->sun_path) + offsetof(struct sockaddr_un, sun_path))
+#endif
+
 /*----- Data structures ---------------------------------------------------*/
 
-enum { UNUSED, STALE, USED };		/* Unix socket status values */
+/* Unix socket status values. */
+#define UNUSED 0u			/* No sign of anyone using it */
+#define STALE 1u			/* Socket exists, but is abandoned */
+#define USED 16u			/* Socket is in active use */
+#define LISTEN 2u			/* Socket has an active listener */
+
 enum { DENY, ALLOW };			/* ACL verdicts */
 
 static int address_families[] = { AF_INET, AF_INET6, -1 };
@@ -676,6 +686,7 @@ static int unix_socket_status(struct sockaddr_un *sun, int quickp)
   FILE *fp = 0;
   size_t len, n;
   int rc;
+  unsigned long f;
   char buf[256];
 
   /* If we can't find the socket node, then it's definitely not in use.  If
@@ -700,15 +711,19 @@ static int unix_socket_status(struct sockaddr_un *sun, int quickp)
     goto done;
   if (!fgets(buf, sizeof(buf), fp)) goto done; /* skip header */
   len = strlen(sun->sun_path);
+  rc = 0;
   while (fgets(buf, sizeof(buf), fp)) {
     n = strlen(buf);
     if (n >= len + 2 && buf[n - len - 2] == ' ' && buf[n - 1] == '\n' &&
-	memcmp(buf + n - len - 1, sun->sun_path, len) == 0)
-      goto done;
+	memcmp(buf + n - len - 1, sun->sun_path, len) == 0) {
+      rc |= USED;
+      if (sscanf(buf, "%*s %*x %*x %lx", &f) < 0 || (f&0x00010000))
+	rc |= LISTEN;
+    }
   }
   if (ferror(fp))
     goto done;
-  rc = STALE;
+  if (!rc) rc = STALE;
 done:
   if (fp) fclose(fp);
 
@@ -728,9 +743,9 @@ static int encode_single_inet_addr(const struct sockaddr *sa,
 
   snprintf(sun->sun_path, sizeof(sun->sun_path), "%s/%s", sockdir,
 	   present_sockaddr(sa, 0, buf, sizeof(buf)));
-  if ((rc = unix_socket_status(sun, quickp)) == USED) return (USED);
-  else if (rc == STALE) unlink(sun->sun_path);
-  return (UNUSED);
+  rc = unix_socket_status(sun, quickp);
+  if (rc == STALE) unlink(sun->sun_path);
+  return (rc);
 }
 
 /* Convert the IP address SA to a Unix-domain address SUN.  Fail if the
@@ -749,7 +764,7 @@ static int encode_unused_inet_addr(struct sockaddr *sa,
    * desperate.  If the socket is in use, we fail here.  (This could get
    * racy.  Let's not worry about that for now.)
    */
-  if (encode_single_inet_addr(sa, sun, !desperatep) == USED)
+  if (encode_single_inet_addr(sa, sun, !desperatep)&USED)
     return (-1);
 
   /* Next, check the corresponding wildcard address, so as to avoid
@@ -757,7 +772,7 @@ static int encode_unused_inet_addr(struct sockaddr *sa,
    */
   wildcard_address(sa->sa_family, &waddr.sa);
   port_to_sockaddr(&waddr.sa, port);
-  if (encode_single_inet_addr(&waddr.sa, &wsun, !desperatep) == USED)
+  if (encode_single_inet_addr(&waddr.sa, &wsun, !desperatep)&USED)
     return (-1);
 
   /* We're not done yet.  If this is an IPv4 address, then /also/ check (a)
@@ -766,16 +781,16 @@ static int encode_unused_inet_addr(struct sockaddr *sa,
    */
   if (sa->sa_family == AF_INET) {
     map_ipv4_sockaddr(&maddr.sin6, SIN(&sa));
-    if (encode_single_inet_addr(&maddr.sa, &wsun, !desperatep) == USED)
+    if (encode_single_inet_addr(&maddr.sa, &wsun, !desperatep)&USED)
       return (-1);
 
     map_ipv4_sockaddr(&maddr.sin6, &waddr.sin);
-    if (encode_single_inet_addr(&maddr.sa, &wsun, !desperatep) == USED)
+    if (encode_single_inet_addr(&maddr.sa, &wsun, !desperatep)&USED)
       return (-1);
 
     wildcard_address(AF_INET6, &waddr.sa);
     port_to_sockaddr(&waddr.sa, port);
-    if (encode_single_inet_addr(&waddr.sa, &wsun, !desperatep) == USED)
+    if (encode_single_inet_addr(&waddr.sa, &wsun, !desperatep)&USED)
       return (-1);
   }
 
@@ -790,6 +805,7 @@ static int encode_unused_inet_addr(struct sockaddr *sa,
  * Returns zero on success; -1 on failure.
  */
 #define ENCF_FRESH 1u
+#define ENCF_REUSEADDR 2u
 static int encode_inet_addr(struct sockaddr_un *sun,
 			    const struct sockaddr *sa,
 			    unsigned f)
@@ -799,6 +815,7 @@ static int encode_inet_addr(struct sockaddr_un *sun,
   address addr;
   struct sockaddr_in6 sin6;
   int port = port_from_sockaddr(sa);
+  int rc;
   char buf[ADDRBUFSZ];
 
   D( fprintf(stderr, "noip(%d): encode %s (%s)", getpid(),
@@ -813,8 +830,9 @@ static int encode_inet_addr(struct sockaddr_un *sun,
     /* Try the address as given.  If it's in use, or we don't necessarily
      * want an existing socket, then we're done.
      */
-    if (encode_single_inet_addr(sa, sun, 0) == USED || (f&ENCF_FRESH))
-      goto found;
+    rc = encode_single_inet_addr(sa, sun, 0);
+    if ((f&ENCF_REUSEADDR) && !(rc&LISTEN)) unlink(sun->sun_path);
+    if ((rc&USED) || (f&ENCF_FRESH)) goto found;
 
     /* We're looking for a socket which already exists.  This is
      * unfortunately difficult, because we must deal both with wildcards and
@@ -836,19 +854,19 @@ static int encode_inet_addr(struct sockaddr_un *sun,
 
     if (sa->sa_family == AF_INET) {
       map_ipv4_sockaddr(&addr.sin6, SIN(sa));
-      if (encode_single_inet_addr(&addr.sa, sun, 0) == USED) goto found;
+      if (encode_single_inet_addr(&addr.sa, sun, 0)&USED) goto found;
     }
 
     wildcard_address(sa->sa_family, &addr.sa);
     port_to_sockaddr(&addr.sa, port);
-    if (encode_single_inet_addr(&addr.sa, sun, 0) == USED) goto found;
+    if (encode_single_inet_addr(&addr.sa, sun, 0)&USED) goto found;
 
     if (sa->sa_family == AF_INET) {
       map_ipv4_sockaddr(&sin6, &addr.sin);
-      if (encode_single_inet_addr(SA(&sin6), sun, 0) == USED) goto found;
+      if (encode_single_inet_addr(SA(&sin6), sun, 0)&USED) goto found;
       wildcard_address(AF_INET6, &addr.sa);
       port_to_sockaddr(&addr.sa, port);
-      if (encode_single_inet_addr(&addr.sa, sun, 0) == USED) goto found;
+      if (encode_single_inet_addr(&addr.sa, sun, 0)&USED) goto found;
     }
 
     /* Well, this isn't going to work (unless a miraculous race is lost), but
@@ -1109,7 +1127,11 @@ static int do_implicit_bind(int sk, const struct sockaddr *sa, unsigned f)
 	sockaddr_in_range_p(sa, &i->minaddr, &i->maxaddr)) {
       D( fprintf(stderr, "noip(%d): match!\n", pid); )
       addr.sa.sa_family = sa->sa_family;
-      ipaddr_to_sockaddr(&addr.sa, &i->bindaddr);
+      switch (i->how) {
+	case EXPLICIT: ipaddr_to_sockaddr(&addr.sa, &i->bindaddr); break;
+	case SAME: copy_sockaddr(&addr.sa, sa); break;
+      }
+      port_to_sockaddr(&addr.sa, 0);
       goto found;
     }
   }
@@ -1712,6 +1734,9 @@ int bind(int sk, const struct sockaddr *sa, socklen_t len)
 {
   struct sockaddr_un sun;
   int rc;
+  unsigned f;
+  int reusep;
+  socklen_t n;
   Dpid;
 
   D({ char buf[ADDRBUFSZ];
@@ -1727,7 +1752,11 @@ int bind(int sk, const struct sockaddr *sa, socklen_t len)
 	if (fixup_real_ip_socket(sk, sa->sa_family, 0))
 	  return (-1);
       } else {
-	encode_inet_addr(&sun, sa, ENCF_FRESH);
+	f = ENCF_FRESH;
+	n = sizeof(reusep);
+	if (!getsockopt(sk, SOL_SOCKET, SO_REUSEADDR, &reusep, &n) && reusep)
+	  f |= ENCF_REUSEADDR;
+	encode_inet_addr(&sun, sa, f);
 	sa = SA(&sun);
 	len = SUN_LEN(&sun);
       }
@@ -1945,7 +1974,7 @@ int getpeername(int sk, struct sockaddr *sa, socklen_t *len)
     D( fprintf(stderr, "noip(%d): ... GETPEERNAME", pid); )
   }
   D( dump_addrresult(rc, sa, *len); )
-  return (0);
+  return (rc);
 }
 
 int getsockopt(int sk, int lev, int opt, void *p, socklen_t *len)