+#if 0
+struct stmt *
+gen_joinsp(s, n)
+ struct stmt **s;
+ int n;
+{
+ return NULL;
+}
+#endif
+
+static struct block *
+gen_protochain(v, proto, dir)
+ int v;
+ int proto;
+ int dir;
+{
+#ifdef NO_PROTOCHAIN
+ return gen_proto(v, proto, dir);
+#else
+ struct block *b0, *b;
+ struct slist *s[100];
+ int fix2, fix3, fix4, fix5;
+ int ahcheck, again, end;
+ int i, max;
+ int reg1 = alloc_reg();
+ int reg2 = alloc_reg();
+
+ memset(s, 0, sizeof(s));
+ fix2 = fix3 = fix4 = fix5 = 0;
+
+ switch (proto) {
+ case Q_IP:
+ case Q_IPV6:
+ break;
+ case Q_DEFAULT:
+ b0 = gen_protochain(v, Q_IP, dir);
+ b = gen_protochain(v, Q_IPV6, dir);
+ gen_or(b0, b);
+ return b;
+ default:
+ bpf_error("bad protocol applied for 'protochain'");
+ /*NOTREACHED*/
+ }
+
+ no_optimize = 1; /*this code is not compatible with optimzer yet */
+
+ /*
+ * s[0] is a dummy entry to protect other BPF insn from damaged
+ * by s[fix] = foo with uninitialized variable "fix". It is somewhat
+ * hard to find interdependency made by jump table fixup.
+ */
+ i = 0;
+ s[i] = new_stmt(0); /*dummy*/
+ i++;
+
+ switch (proto) {
+ case Q_IP:
+ b0 = gen_linktype(ETHERTYPE_IP);
+
+ /* A = ip->ip_p */
+ s[i] = new_stmt(BPF_LD|BPF_ABS|BPF_B);
+ s[i]->s.k = off_nl + 9;
+ i++;
+ /* X = ip->ip_hl << 2 */
+ s[i] = new_stmt(BPF_LDX|BPF_MSH|BPF_B);
+ s[i]->s.k = off_nl;
+ i++;
+ break;
+#ifdef INET6
+ case Q_IPV6:
+ b0 = gen_linktype(ETHERTYPE_IPV6);
+
+ /* A = ip6->ip_nxt */
+ s[i] = new_stmt(BPF_LD|BPF_ABS|BPF_B);
+ s[i]->s.k = off_nl + 6;
+ i++;
+ /* X = sizeof(struct ip6_hdr) */
+ s[i] = new_stmt(BPF_LDX|BPF_IMM);
+ s[i]->s.k = 40;
+ i++;
+ break;
+#endif
+ default:
+ bpf_error("unsupported proto to gen_protochain");
+ /*NOTREACHED*/
+ }
+
+ /* again: if (A == v) goto end; else fall through; */
+ again = i;
+ s[i] = new_stmt(BPF_JMP|BPF_JEQ|BPF_K);
+ s[i]->s.k = v;
+ s[i]->s.jt = NULL; /*later*/
+ s[i]->s.jf = NULL; /*update in next stmt*/
+ fix5 = i;
+ i++;
+
+#ifndef IPPROTO_NONE
+#define IPPROTO_NONE 59
+#endif
+ /* if (A == IPPROTO_NONE) goto end */
+ s[i] = new_stmt(BPF_JMP|BPF_JEQ|BPF_K);
+ s[i]->s.jt = NULL; /*later*/
+ s[i]->s.jf = NULL; /*update in next stmt*/
+ s[i]->s.k = IPPROTO_NONE;
+ s[fix5]->s.jf = s[i];
+ fix2 = i;
+ i++;
+
+#ifdef INET6
+ if (proto == Q_IPV6) {
+ int v6start, v6end, v6advance, j;
+
+ v6start = i;
+ /* if (A == IPPROTO_HOPOPTS) goto v6advance */
+ s[i] = new_stmt(BPF_JMP|BPF_JEQ|BPF_K);
+ s[i]->s.jt = NULL; /*later*/
+ s[i]->s.jf = NULL; /*update in next stmt*/
+ s[i]->s.k = IPPROTO_HOPOPTS;
+ s[fix2]->s.jf = s[i];
+ i++;
+ /* if (A == IPPROTO_DSTOPTS) goto v6advance */
+ s[i - 1]->s.jf = s[i] = new_stmt(BPF_JMP|BPF_JEQ|BPF_K);
+ s[i]->s.jt = NULL; /*later*/
+ s[i]->s.jf = NULL; /*update in next stmt*/
+ s[i]->s.k = IPPROTO_DSTOPTS;
+ i++;
+ /* if (A == IPPROTO_ROUTING) goto v6advance */
+ s[i - 1]->s.jf = s[i] = new_stmt(BPF_JMP|BPF_JEQ|BPF_K);
+ s[i]->s.jt = NULL; /*later*/
+ s[i]->s.jf = NULL; /*update in next stmt*/
+ s[i]->s.k = IPPROTO_ROUTING;
+ i++;
+ /* if (A == IPPROTO_FRAGMENT) goto v6advance; else goto ahcheck; */
+ s[i - 1]->s.jf = s[i] = new_stmt(BPF_JMP|BPF_JEQ|BPF_K);
+ s[i]->s.jt = NULL; /*later*/
+ s[i]->s.jf = NULL; /*later*/
+ s[i]->s.k = IPPROTO_FRAGMENT;
+ fix3 = i;
+ v6end = i;
+ i++;
+
+ /* v6advance: */
+ v6advance = i;
+
+ /*
+ * in short,
+ * A = P[X + 1];
+ * X = X + (P[X] + 1) * 8;
+ */
+ /* A = X */
+ s[i] = new_stmt(BPF_MISC|BPF_TXA);
+ i++;
+ /* MEM[reg1] = A */
+ s[i] = new_stmt(BPF_ST);
+ s[i]->s.k = reg1;
+ 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]; */
+ s[i] = new_stmt(BPF_LD|BPF_IND|BPF_B);
+ s[i]->s.k = off_nl;
+ i++;
+ /* MEM[reg2] = A */
+ s[i] = new_stmt(BPF_ST);
+ s[i]->s.k = reg2;
+ i++;
+ /* X = MEM[reg1] */
+ s[i] = new_stmt(BPF_LDX|BPF_MEM);
+ s[i]->s.k = reg1;
+ i++;
+ /* A = P[X + packet head] */
+ s[i] = new_stmt(BPF_LD|BPF_IND|BPF_B);
+ s[i]->s.k = off_nl;
+ i++;
+ /* A += 1 */
+ s[i] = new_stmt(BPF_ALU|BPF_ADD|BPF_K);
+ s[i]->s.k = 1;
+ i++;
+ /* A *= 8 */
+ s[i] = new_stmt(BPF_ALU|BPF_MUL|BPF_K);
+ s[i]->s.k = 8;
+ i++;
+ /* X = A; */
+ s[i] = new_stmt(BPF_MISC|BPF_TAX);
+ i++;
+ /* A = MEM[reg2] */
+ s[i] = new_stmt(BPF_LD|BPF_MEM);
+ s[i]->s.k = reg2;
+ i++;
+
+ /* goto again; (must use BPF_JA for backward jump) */
+ s[i] = new_stmt(BPF_JMP|BPF_JA);
+ s[i]->s.k = again - i - 1;
+ s[i - 1]->s.jf = s[i];
+ i++;
+
+ /* fixup */
+ for (j = v6start; j <= v6end; j++)
+ s[j]->s.jt = s[v6advance];
+ } else
+#endif
+ {
+ /* nop */
+ s[i] = new_stmt(BPF_ALU|BPF_ADD|BPF_K);
+ s[i]->s.k = 0;
+ s[fix2]->s.jf = s[i];
+ i++;
+ }
+
+ /* ahcheck: */
+ ahcheck = i;
+ /* if (A == IPPROTO_AH) then fall through; else goto end; */
+ s[i] = new_stmt(BPF_JMP|BPF_JEQ|BPF_K);
+ s[i]->s.jt = NULL; /*later*/
+ s[i]->s.jf = NULL; /*later*/
+ s[i]->s.k = IPPROTO_AH;
+ if (fix3)
+ s[fix3]->s.jf = s[ahcheck];
+ fix4 = i;
+ i++;
+
+ /*
+ * in short,
+ * A = P[X + 1];
+ * X = X + (P[X] + 2) * 4;
+ */
+ /* A = X */
+ s[i - 1]->s.jt = s[i] = new_stmt(BPF_MISC|BPF_TXA);
+ i++;
+ /* MEM[reg1] = A */
+ s[i] = new_stmt(BPF_ST);
+ s[i]->s.k = reg1;
+ 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]; */
+ s[i] = new_stmt(BPF_LD|BPF_IND|BPF_B);
+ s[i]->s.k = off_nl;
+ i++;
+ /* MEM[reg2] = A */
+ s[i] = new_stmt(BPF_ST);
+ s[i]->s.k = reg2;
+ i++;
+ /* X = MEM[reg1] */
+ s[i] = new_stmt(BPF_LDX|BPF_MEM);
+ s[i]->s.k = reg1;
+ i++;
+ /* A = P[X + packet head] */
+ s[i] = new_stmt(BPF_LD|BPF_IND|BPF_B);
+ s[i]->s.k = off_nl;
+ i++;
+ /* A += 2 */
+ s[i] = new_stmt(BPF_ALU|BPF_ADD|BPF_K);
+ s[i]->s.k = 2;
+ i++;
+ /* A *= 4 */
+ s[i] = new_stmt(BPF_ALU|BPF_MUL|BPF_K);
+ s[i]->s.k = 4;
+ i++;
+ /* X = A; */
+ s[i] = new_stmt(BPF_MISC|BPF_TAX);
+ i++;
+ /* A = MEM[reg2] */
+ s[i] = new_stmt(BPF_LD|BPF_MEM);
+ s[i]->s.k = reg2;
+ i++;
+
+ /* goto again; (must use BPF_JA for backward jump) */
+ s[i] = new_stmt(BPF_JMP|BPF_JA);
+ s[i]->s.k = again - i - 1;
+ i++;
+
+ /* end: nop */
+ end = i;
+ s[i] = new_stmt(BPF_ALU|BPF_ADD|BPF_K);
+ s[i]->s.k = 0;
+ s[fix2]->s.jt = s[end];
+ s[fix4]->s.jf = s[end];
+ s[fix5]->s.jt = s[end];
+ i++;
+
+ /*
+ * make slist chain
+ */
+ max = i;
+ for (i = 0; i < max - 1; i++)
+ s[i]->next = s[i + 1];
+ s[max - 1]->next = NULL;
+
+ /*
+ * emit final check
+ */
+ b = new_block(JMP(BPF_JEQ));
+ b->stmts = s[1]; /*remember, s[0] is dummy*/
+ b->s.k = v;
+
+ free_reg(reg1);
+ free_reg(reg2);
+
+ gen_and(b0, b);
+ return b;
+#endif
+}
+
projects / libpcap / blobdiff