Add random commentary to SOCKS code.

[u/mdw/putty] / portfwd.c

diff --git a/portfwd.c b/portfwd.c
index a8c8b04..f740267 100644 (file)
--- a/portfwd.c
+++ b/portfwd.c
@@ -107,6 +107,10 @@ static int pfd_receive(Plug plug, int urgent, char *data, int len)
     struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
     if (pr->dynamic) {
        while (len--) {
+           /*
+            * Throughout SOCKS negotiation, "hostname" is re-used as a
+            * random protocol buffer with "port" storing the length.
+            */ 
            if (pr->port >= lenof(pr->hostname)) {
                /* Request too long. */
                if ((pr->dynamic >> 12) == 4) {
@@ -134,6 +138,7 @@ static int pfd_receive(Plug plug, int urgent, char *data, int len)
                    pr->dynamic = 0x4000;
                if (pr->port < 2) continue;/* don't have command code yet */
                if (pr->hostname[1] != 1) {
+                   /* Not CONNECT. */
                    /* Send back a SOCKS 4 error before closing. */
                    char data[8];
                    memset(data, 0, sizeof(data));
@@ -142,9 +147,9 @@ static int pfd_receive(Plug plug, int urgent, char *data, int len)
                    pfd_close(pr->s);
                    return 1;
                }
-               if (pr->port < 8) continue;   /* haven't started username */
+               if (pr->port <= 8) continue; /* haven't started user/hostname */
                if (pr->hostname[pr->port-1] != 0)
-                   continue;          /* haven't _finished_ username */
+                   continue;          /* haven't _finished_ user/hostname */
                /*
                 * Now we have a full SOCKS 4 request. Check it to
                 * see if it's a SOCKS 4A request.
@@ -166,7 +171,7 @@ static int pfd_receive(Plug plug, int urgent, char *data, int len)
                    pr->hostname[0] = 0;   /* reply version code */
                    pr->hostname[1] = 90;   /* request granted */
                    sk_write(pr->s, pr->hostname, 8);
-                   len= pr->port;
+                   len= pr->port - 8;
                    pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2);
                    memmove(pr->hostname, pr->hostname + 8, len);
                    goto connect;
@@ -432,7 +437,7 @@ static int pfd_accepting(Plug p, OSSocket sock)
 
     if (org->dynamic) {
        pr->dynamic = 1;
-       pr->port = 0;                  /* hostname buffer is so far empty */
+       pr->port = 0;                  /* "hostname" buffer is so far empty */
        sk_set_frozen(s, 0);           /* we want to receive SOCKS _now_! */
     } else {
        pr->dynamic = 0;