Fix the code generated for "ip protochain".

diff --git a/gencode.c b/gencode.c
index cb6a12cc6008fa5465dbc16a47962c62aa81a85a..292023eb4c50f03f248735b3cddf2456b1d8cc44 100644 (file)
--- a/gencode.c
+++ b/gencode.c
@@ -5814,12 +5814,9 @@ gen_protochain(v, proto, dir)
 
                /*
                 * in short,
-                * A = P[X];
-                * X = X + (P[X + 1] + 1) * 8;
+                * A = P[X + packet head];
+                * X = X + (P[X + packet head + 1] + 1) * 8;
                 */
-               /* A = X */
-               s[i] = new_stmt(BPF_MISC|BPF_TXA);
-               i++;
                /* A = P[X + packet head] */
                s[i] = new_stmt(BPF_LD|BPF_IND|BPF_B);
                s[i]->s.k = off_macpl + off_nl;
@@ -5828,19 +5825,9 @@ gen_protochain(v, proto, dir)
                s[i] = new_stmt(BPF_ST);
                s[i]->s.k = reg2;
                i++;
-               /* A = X */
-               s[i] = new_stmt(BPF_MISC|BPF_TXA);
-               i++;
-               /* A += 1 */
-               s[i] = new_stmt(BPF_ALU|BPF_ADD|BPF_K);
-               s[i]->s.k = 1;
-               i++;
-               /* X = A */
-               s[i] = new_stmt(BPF_MISC|BPF_TAX);
-               i++;
-               /* A = P[X + packet head]; */
+               /* A = P[X + packet head + 1]; */
                s[i] = new_stmt(BPF_LD|BPF_IND|BPF_B);
-               s[i]->s.k = off_macpl + off_nl;
+               s[i]->s.k = off_macpl + off_nl + 1;
                i++;
                /* A += 1 */
                s[i] = new_stmt(BPF_ALU|BPF_ADD|BPF_K);
@@ -5850,6 +5837,10 @@ gen_protochain(v, proto, dir)
                s[i] = new_stmt(BPF_ALU|BPF_MUL|BPF_K);
                s[i]->s.k = 8;
                i++;
+               /* A += X */
+               s[i] = new_stmt(BPF_ALU|BPF_ADD|BPF_X);
+               s[i]->s.k = 0;
+               i++;
                /* X = A; */
                s[i] = new_stmt(BPF_MISC|BPF_TAX);
                i++;