chiark / gitweb /
site, transform: per-transform-instance max_start_pad
[secnet.git] / slip.c
diff --git a/slip.c b/slip.c
index fe6cb15..d8f1a17 100644 (file)
--- a/slip.c
+++ b/slip.c
@@ -7,6 +7,7 @@
 #include "util.h"
 #include "netlink.h"
 #include "process.h"
+#include "unaligned.h"
 #include <stdio.h>
 #include <string.h>
 #include <unistd.h>
@@ -23,6 +24,8 @@ struct slip {
     struct buffer_if *buff; /* We unstuff received packets into here
                               and send them to the netlink code. */
     bool_t pending_esc;
+    bool_t ignoring_packet; /* If this packet was corrupt or overlong,
+                              we ignore everything up to the next END */
     netlink_deliver_fn *netlink_to_tunnel;
     uint32_t local_address;
 };
@@ -33,7 +36,7 @@ static void slip_stuff(struct slip *st, struct buffer_if *buf, int fd)
 {
     uint8_t txbuf[DEFAULT_BUFSIZE];
     uint8_t *i;
-    uint32_t j=0;
+    int32_t j=0;
 
     BUF_ASSERT_USED(buf);
 
@@ -73,40 +76,69 @@ static void slip_unstuff(struct slip *st, uint8_t *buf, uint32_t l)
 
     BUF_ASSERT_USED(st->buff);
     for (i=0; i<l; i++) {
+       int outputchr;
+       enum { OUTPUT_END = 256, OUTPUT_NOTHING = 257 };
+
        if (st->pending_esc) {
            st->pending_esc=False;
            switch(buf[i]) {
            case SLIP_ESCEND:
-               *(uint8_t *)buf_append(st->buff,1)=SLIP_END;
+               outputchr=SLIP_END;
                break;
            case SLIP_ESCESC:
-               *(uint8_t *)buf_append(st->buff,1)=SLIP_ESC;
+               outputchr=SLIP_ESC;
                break;
            default:
-               fatal("userv_afterpoll: bad SLIP escape character\n");
+               if (!st->ignoring_packet) {
+                   Message(M_WARNING, "userv_afterpoll: bad SLIP escape"
+                           " character, dropping packet\n");
+               }
+               st->ignoring_packet=True;
+               outputchr=OUTPUT_NOTHING;
+               break;
            }
        } else {
            switch (buf[i]) {
            case SLIP_END:
-               if (st->buff->size>0) {
-                   st->netlink_to_tunnel(&st->nl,st->buff);
-                   BUF_ALLOC(st->buff,"userv_afterpoll");
-               }
-               buffer_init(st->buff,st->nl.max_start_pad);
+               outputchr=OUTPUT_END;
                break;
            case SLIP_ESC:
                st->pending_esc=True;
+               outputchr=OUTPUT_NOTHING;
                break;
            default:
-               *(uint8_t *)buf_append(st->buff,1)=buf[i];
+               outputchr=buf[i];
                break;
            }
        }
+
+       if (st->ignoring_packet) {
+           if (outputchr == OUTPUT_END) {
+               st->ignoring_packet=False;
+               buffer_init(st->buff,st->nl.max_start_pad);
+           }
+       } else {
+           if (outputchr == OUTPUT_END) {
+               if (st->buff->size>0) {
+                   st->netlink_to_tunnel(&st->nl,st->buff);
+                   BUF_ALLOC(st->buff,"userv_afterpoll");
+               }
+               buffer_init(st->buff,st->nl.max_start_pad);
+           } else if (outputchr != OUTPUT_NOTHING) {
+               if (st->buff->size < st->buff->len) {
+                   buf_append_uint8(st->buff,outputchr);
+               } else {
+                   Message(M_WARNING, "userv_afterpoll: dropping overlong"
+                           " SLIP packet\n");
+                   st->ignoring_packet=True;
+               }
+           }
+       }
     }
 }
 
 static void slip_init(struct slip *st, struct cloc loc, dict_t *dict,
-                     string_t name, netlink_deliver_fn *to_host)
+                     cstring_t name, netlink_deliver_fn *to_host)
 {
     st->netlink_to_tunnel=
        netlink_init(&st->nl,st,loc,dict,
@@ -116,6 +148,7 @@ static void slip_init(struct slip *st, struct cloc loc, dict_t *dict,
        dict_find_item(dict,"local-address", True, name, loc),"netlink");
     BUF_ALLOC(st->buff,"slip_init");
     st->pending_esc=False;
+    st->ignoring_packet=False;
 }
 
 /* Connection to the kernel through userv-ipif */
@@ -124,33 +157,31 @@ struct userv {
     struct slip slip;
     int txfd; /* We transmit to userv */
     int rxfd; /* We receive from userv */
-    string_t userv_path;
-    string_t service_user;
-    string_t service_name;
+    cstring_t userv_path;
+    cstring_t service_user;
+    cstring_t service_name;
     pid_t pid;
     bool_t expecting_userv_exit;
 };
 
 static int userv_beforepoll(void *sst, struct pollfd *fds, int *nfds_io,
-                           int *timeout_io, const struct timeval *tv_now,
-                           uint64_t *now)
+                           int *timeout_io)
 {
     struct userv *st=sst;
 
     if (st->rxfd!=-1) {
        *nfds_io=2;
        fds[0].fd=st->txfd;
-       fds[0].events=POLLERR; /* Might want to pick up POLLOUT sometime */
+       fds[0].events=0; /* Might want to pick up POLLOUT sometime */
        fds[1].fd=st->rxfd;
-       fds[1].events=POLLIN|POLLERR|POLLHUP;
+       fds[1].events=POLLIN;
     } else {
        *nfds_io=0;
     }
     return 0;
 }
 
-static void userv_afterpoll(void *sst, struct pollfd *fds, int nfds,
-                           const struct timeval *tv_now, uint64_t *now)
+static void userv_afterpoll(void *sst, struct pollfd *fds, int nfds)
 {
     struct userv *st=sst;
     uint8_t rxbuf[DEFAULT_BUFSIZE];
@@ -168,7 +199,7 @@ static void userv_afterpoll(void *sst, struct pollfd *fds, int nfds,
                fatal_perror("%s: userv_afterpoll: read(rxfd)",
                             st->slip.nl.name);
        } else if (l==0) {
-           fatal("%s: userv_afterpoll: read(rxfd)=0; userv gone away?\n",
+           fatal("%s: userv_afterpoll: read(rxfd)=0; userv gone away?",
                  st->slip.nl.name);
        } else slip_unstuff(&st->slip,rxbuf,l);
     }
@@ -193,13 +224,13 @@ static void userv_userv_callback(void *sst, pid_t pid, int status)
     }
     if (!st->expecting_userv_exit) {
        if (WIFEXITED(status)) {
-           fatal("%s: userv exited unexpectedly with status %d\n",
+           fatal("%s: userv exited unexpectedly with status %d",
                  st->slip.nl.name,WEXITSTATUS(status));
        } else if (WIFSIGNALED(status)) {
-           fatal("%s: userv exited unexpectedly: uncaught signal %d\n",
+           fatal("%s: userv exited unexpectedly: uncaught signal %d",
                  st->slip.nl.name,WTERMSIG(status));
        } else {
-           fatal("%s: userv stopped unexpectedly\n");
+           fatal("%s: userv stopped unexpectedly");
        }
     }
     Message(M_WARNING,"%s: userv subprocess died with status %d\n",
@@ -208,8 +239,8 @@ static void userv_userv_callback(void *sst, pid_t pid, int status)
 }
 
 struct userv_entry_rec {
-    string_t path;
-    char **argv;
+    cstring_t path;
+    const char **argv;
     int in;
     int out;
     /* XXX perhaps we should collect and log stderr? */
@@ -224,7 +255,9 @@ static void userv_entry(void *sst)
 
     /* XXX close all other fds */
     setsid();
-    execvp(st->path,st->argv);
+    /* XXX We really should strdup() all of argv[] but because we'll just
+       exit anyway if execvp() fails it doesn't seem worth bothering. */
+    execvp(st->path,(char *const*)st->argv);
     perror("userv-entry: execvp()");
     exit(1);
 }
@@ -240,11 +273,11 @@ static void userv_invoke_userv(struct userv *st)
     struct netlink_client *r;
     struct ipset *allnets;
     struct subnet_list *snets;
-    int i;
+    int i, nread;
     uint8_t confirm;
 
     if (st->pid) {
-       fatal("userv_invoke_userv: already running\n");
+       fatal("userv_invoke_userv: already running");
     }
 
     /* This is where we actually invoke userv - all the networks we'll
@@ -257,7 +290,7 @@ static void userv_invoke_userv(struct userv *st)
 
     allnets=ipset_new();
     for (r=st->slip.nl.clients; r; r=r->next) {
-       if (r->up) {
+       if (r->link_quality > LINK_QUALITY_UNUSED) {
            struct ipset *nan;
            r->kup=True;
            nan=ipset_union(allnets,r->networks);
@@ -323,23 +356,25 @@ static void userv_invoke_userv(struct userv *st)
     Message(M_INFO,"%s: userv-ipif pid is %d\n",st->slip.nl.name,st->pid);
     /* Read a single character from the pipe to confirm userv-ipif is
        running. If we get a SIGCHLD at this point then we'll get EINTR. */
-    if (read(st->rxfd,&confirm,1)!=1) {
+    if ((nread=read(st->rxfd,&confirm,1))!=1) {
        if (errno==EINTR) {
            Message(M_WARNING,"%s: read of confirmation byte was "
                    "interrupted\n",st->slip.nl.name);
        } else {
-           fatal_perror("%s: read() of confirmation byte",st->slip.nl.name);
+           if (nread<0) {
+               fatal_perror("%s: error reading confirmation byte",
+                            st->slip.nl.name);
+           } else {
+               fatal("%s: unexpected EOF instead of confirmation byte"
+                     " - userv ipif failed?", st->slip.nl.name);
+           }
        }
     } else {
        if (confirm!=SLIP_END) {
-           fatal("%s: bad confirmation byte %d from userv-ipif\n",
+           fatal("%s: bad confirmation byte %d from userv-ipif",
                  st->slip.nl.name,confirm);
        }
     }
-    /* Mark rxfd non-blocking */
-    if (fcntl(st->rxfd, F_SETFL, fcntl(st->rxfd, F_GETFL)|O_NONBLOCK)==-1) {
-       fatal_perror("%s: fcntl(O_NONBLOCK)",st->slip.nl.name);
-    }
 }
 
 static void userv_kill_userv(struct userv *st)
@@ -403,7 +438,6 @@ static list_t *userv_apply(closure_t *self, struct cloc loc, dict_t *context,
     return new_closure(&st->slip.nl.cl);
 }
 
-init_module slip_module;
 void slip_module(dict_t *dict)
 {
     add_closure(dict,"userv-ipif",userv_apply);