slip: Buffer management (max_start_pad) fixes

Nothing in slip.c calls buffer_init for the first packet.  We don't
normally notice this because userv-ipif _both_ prints a confirmation
END byte right away, _and_ bookends packets with ENDs.

But this should be fixed.  Otherwise we fail an assertion when we try
to prepend things to the first data packet.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

diff --git a/netlink.c b/netlink.c
index 173d412..bc70757 100644 (file)
--- a/netlink.c
+++ b/netlink.c
@@ -603,11 +603,13 @@ static void netlink_incoming(struct netlink *st, struct netlink_client *client,
     uint32_t source,dest;
     struct iphdr *iph;
     char errmsgbuf[50];
+    const char *sourcedesc=client?client->name:"host";
 
     BUF_ASSERT_USED(buf);
+
     if (!netlink_check(st,buf,errmsgbuf,sizeof(errmsgbuf))) {
        Message(M_WARNING,"%s: bad IP packet from %s: %s\n",
-               st->name,client?client->name:"host",
+               st->name,sourcedesc,
                errmsgbuf);
        BUF_FREE(buf);
        return;

diff --git a/slip.c b/slip.c
index 5eb8dbd..9e63cb3 100644 (file)
--- a/slip.c
+++ b/slip.c
@@ -79,6 +79,9 @@ static void slip_unstuff(struct slip *st, uint8_t *buf, uint32_t l)
        int outputchr;
        enum { OUTPUT_END = 256, OUTPUT_NOTHING = 257 };
 
+       if (!st->buff->size)
+           buffer_init(st->buff,calculate_max_start_pad());
+
        if (st->pending_esc) {
            st->pending_esc=False;
            switch(buf[i]) {
@@ -115,7 +118,7 @@ static void slip_unstuff(struct slip *st, uint8_t *buf, uint32_t l)
        if (st->ignoring_packet) {
            if (outputchr == OUTPUT_END) {
                st->ignoring_packet=False;
-               buffer_init(st->buff,calculate_max_start_pad());
+               st->buff->size=0;
            }
        } else {
            if (outputchr == OUTPUT_END) {
@@ -123,7 +126,7 @@ static void slip_unstuff(struct slip *st, uint8_t *buf, uint32_t l)
                    st->netlink_to_tunnel(&st->nl,st->buff);
                    BUF_ALLOC(st->buff,"userv_afterpoll");
                }
-               buffer_init(st->buff,calculate_max_start_pad());
+               st->buff->size=0;
            } else if (outputchr != OUTPUT_NOTHING) {
                if (st->buff->size < st->buff->len) {
                    buf_append_uint8(st->buff,outputchr);