Multilink cleanups and fixes.

[ppp.git] / pppd / multilink.c

diff --git a/pppd/multilink.c b/pppd/multilink.c
index 596fd816d24e5332989db20388e5e36dd88a4ca1..546fcaea64004d0d2df991705975de6d90a4761d 100644 (file)
--- a/pppd/multilink.c
+++ b/pppd/multilink.c
@@ -17,6 +17,8 @@
 #include <ctype.h>
 #include <stdlib.h>
 #include <netdb.h>
+#include <errno.h>
+#include <signal.h>
 #include <netinet/in.h>
 
 #include "pppd.h"
@@ -31,6 +33,8 @@ extern TDB_CONTEXT *pppdb;
 extern char db_key[];
 
 static int get_default_epdisc __P((struct epdisc *));
+static int parse_num __P((char *str, const char *key, int *valp));
+static int owns_unit __P((TDB_DATA pid, int unit));
 
 #define set_ip_epdisc(ep, addr) do {   \
        ep->length = 4;                 \
@@ -45,7 +49,8 @@ static int get_default_epdisc __P((struct epdisc *));
         || ((addr) & 0xfff00000) == 0xac100000         /* 172.16.x.x */  \
         || ((addr) & 0xffff0000) == 0xc0a80000)        /* 192.168.x.x */
 
-#ifdef HAVE_MULTILINK
+#define process_exists(n)      (kill(0, (n)) == 0 || errno != ESRCH)
+
 void
 mp_check_options()
 {
@@ -67,13 +72,11 @@ mp_check_options()
                /* get a default endpoint value */
                wo->neg_endpoint = get_default_epdisc(&wo->endpoint);
                if (wo->neg_endpoint)
-                       info("using default endpoint %s",
-                            epdisc_to_str(&wo->endpoint));
+                       dbglog("using default endpoint %s",
+                              epdisc_to_str(&wo->endpoint));
        }
 }
-#endif /* HAVE_MULTILINK */
 
-#ifdef HAVE_MULTILINK
 /*
  * Make a new bundle or join us to an existing bundle
  * if we are doing multilink.
@@ -83,9 +86,9 @@ mp_join_bundle()
 {
        lcp_options *go = &lcp_gotoptions[0];
        lcp_options *ho = &lcp_hisoptions[0];
-       int unit;
-       int i, l;
-       char *p, *endp;
+       int unit, pppd_pid;
+       int l;
+       char *p;
        TDB_DATA key, pid, rec;
 
        if (!go->neg_mrru || !ho->neg_mrru) {
@@ -122,38 +125,39 @@ mp_join_bundle()
                              epdisc_to_str(&ho->endpoint));
        if (bundle_name)
                p += slprintf(p, bundle_id+l-p, "/%v", bundle_name);
-       info("bundle_id = %s", bundle_id+7);
+       dbglog("bundle_id = %s", bundle_id+7);
 
        /*
         * Check if the bundle ID is already in the database.
         */
        unit = -1;
+       pppd_pid = -1;
        key.dptr = bundle_id;
        key.dsize = p - bundle_id;
+       tdb_writelock(pppdb);
        pid = tdb_fetch(pppdb, key);
        if (pid.dptr != NULL) {
                /* bundle ID exists, see if the pppd record still exists */
                rec = tdb_fetch(pppdb, pid);
                if (rec.dptr != NULL) {
                        /* it is, parse the interface number */
-                       p = strstr(rec.dptr, "IFNAME=ppp");
-                       if (p != 0) {
-                               p += 10;        /* skip to unit number */
-                               i = strtol(p, &endp, 10);
-                               if (endp != p && (*endp == 0 || *endp == ';'))
-                                       unit = i;
-                       }
+                       parse_num(rec.dptr, "IFNAME=ppp", &unit);
+                       /* check the pid value */
+                       parse_num(rec.dptr, "PPPD_PID=", &pppd_pid);
+                       if (!process_exists(pppd_pid) || !owns_unit(pid, unit))
+                               unit = -1;
                        free(rec.dptr);
                }
                free(pid.dptr);
        }
 
        if (unit >= 0) {
-               /* attach to existing unit */
+               /* attach to existing unit, if the pid still exists */
                if (bundle_attach(unit)) {
-                       info("attached link to interface %d", ifunit);
+                       dbglog("attached link to interface %d", ifunit);
                        set_ifunit(0);
                        script_setenv("BUNDLE", bundle_id + 7, 0);
+                       tdb_writeunlock(pppdb);
                        return 1;
                }
                /* attach failed because bundle doesn't exist */
@@ -163,11 +167,55 @@ mp_join_bundle()
        make_new_bundle(go->mrru, ho->mrru, go->neg_ssnhf, ho->neg_ssnhf);
        set_ifunit(1);
        script_setenv("BUNDLE", bundle_id + 7, 1);
+       tdb_writeunlock(pppdb);
+       return 0;
+}
+
+static int
+parse_num(str, key, valp)
+     char *str;
+     const char *key;
+     int *valp;
+{
+       char *p, *endp;
+       int i;
+
+       p = strstr(str, key);
+       if (p != 0) {
+               p += strlen(key);
+               i = strtol(p, &endp, 10);
+               if (endp != p && (*endp == 0 || *endp == ';')) {
+                       *valp = i;
+                       return 1;
+               }
+       }
        return 0;
 }
-#endif /* HAVE_MULTILINK */
 
-#ifdef /* HAVE_MULTILINK */
+/*
+ * Check whether the pppd identified by `key' still owns ppp unit `unit'.
+ */
+static int
+owns_unit(key, unit)
+     TDB_DATA key;
+     int unit;
+{
+       char ifkey[32];
+       TDB_DATA kd, vd;
+       int ret = 0;
+
+       slprintf(ifkey, sizeof(ifkey), "IFNAME=ppp%d", unit);
+       kd.dptr = ifkey;
+       kd.dsize = strlen(ifkey);
+       vd = tdb_fetch(pppdb, kd);
+       if (vd.dptr != NULL) {
+               ret = vd.dsize == key.dsize
+                       && memcmp(vd.dptr, key.dptr, vd.dsize) == 0;
+               free(vd.dptr);
+       }
+       return ret;
+}
+
 static int
 get_default_epdisc(ep)
      struct epdisc *ep;
@@ -200,7 +248,6 @@ get_default_epdisc(ep)
 
        return 0;
 }
-#endif /* HAVE_MULTILINK */
 
 /*
  * epdisc_to_str - make a printable string from an endpoint discriminator.
@@ -252,7 +299,6 @@ epdisc_to_str(ep)
        return str;
 }
 
-#ifdef HAVE_MULTILINK
 static int hexc_val(int c)
 {
        if (c >= 'a')
@@ -261,9 +307,7 @@ static int hexc_val(int c)
                return c - 'A' + 10;
        return c - '0';
 }
-#endif /* HAVE_MULTILINK */
 
-#ifdef HAVE_MULTILINK
 int
 str_to_epdisc(ep, str)
      struct epdisc *ep;
@@ -332,5 +376,4 @@ str_to_epdisc(ep, str)
        dbglog("str_to_epdisc -> %s", epdisc_to_str(ep));
        return 1;
 }
-#endif /* HAVE_MULTILINK */