+
+/*
+ * These two functions implement nfs rpc compression.
+ * The algorithm is a trivial run length encoding of '\0' bytes. The high
+ * order nibble of hex "e" is or'd with the number of zeroes - 2 in four
+ * bits. (2 - 17 zeros) Any data byte with a high order nibble of hex "e"
+ * is byte stuffed.
+ * The compressed data is padded with 0x0 bytes to an even multiple of
+ * 4 bytes in length to avoid any weird long pointer alignments.
+ * If compression/uncompression is unsuccessful, the original mbuf list
+ * is returned.
+ * The first four bytes (the XID) are left uncompressed and the fifth
+ * byte is set to 0x1 for request and 0x2 for reply.
+ * An uncompressed RPC will always have the fifth byte == 0x0.
+ */
+struct mbuf *
+nfs_compress(m0)
+ struct mbuf *m0;
+{
+ register u_char ch, nextch;
+ register int i, rlelast;
+ register u_char *ip, *op;
+ register int ileft, oleft, noteof;
+ register struct mbuf *m, *om;
+ struct mbuf **mp, *retm;
+ int olen, clget;
+
+ i = rlelast = 0;
+ noteof = 1;
+ m = m0;
+ if (m->m_len < 12)
+ return (m0);
+ if (m->m_pkthdr.len >= MINCLSIZE)
+ clget = 1;
+ else
+ clget = 0;
+ ileft = m->m_len - 9;
+ ip = mtod(m, u_char *);
+ MGETHDR(om, MT_DATA, M_WAIT);
+ if (clget)
+ MCLGET(om, M_WAIT);
+ retm = om;
+ mp = &om->m_next;
+ olen = om->m_len = 5;
+ oleft = M_TRAILINGSPACE(om);
+ op = mtod(om, u_char *);
+ *((u_long *)op) = *((u_long *)ip);
+ ip += 7;
+ op += 4;
+ *op++ = *ip++ + 1;
+ nextch = *ip++;
+ while (noteof) {
+ ch = nextch;
+ if (ileft == 0) {
+ do {
+ m = m->m_next;
+ } while (m && m->m_len == 0);
+ if (m) {
+ ileft = m->m_len;
+ ip = mtod(m, u_char *);
+ } else {
+ noteof = 0;
+ nextch = 0x1;
+ goto doit;
+ }
+ }
+ nextch = *ip++;
+ ileft--;
+doit:
+ if (ch == '\0') {
+ if (++i == NFSC_MAX || nextch != '\0') {
+ if (i < 2) {
+ nfscput('\0');
+ } else {
+ if (rlelast == i) {
+ nfscput('\0');
+ i--;
+ }
+ if (NFSCRLE(i) == (nextch & 0xff)) {
+ i--;
+ if (i < 2) {
+ nfscput('\0');
+ } else {
+ nfscput(NFSCRLE(i));
+ }
+ nfscput('\0');
+ rlelast = 0;
+ } else {
+ nfscput(NFSCRLE(i));
+ rlelast = i;
+ }
+ }
+ i = 0;
+ }
+ } else {
+ if ((ch & NFSCRL) == NFSCRL) {
+ nfscput(ch);
+ }
+ nfscput(ch);
+ i = rlelast = 0;
+ }
+ }
+ if (olen < m0->m_pkthdr.len) {
+ m_freem(m0);
+ if (i = (olen & 0x3)) {
+ i = 4 - i;
+ while (i-- > 0)
+ nfscput('\0');
+ }
+ retm->m_pkthdr.len = olen;
+ return (retm);
+ } else {
+ m_freem(retm);
+ return (m0);
+ }
+}
+
+struct mbuf *
+nfs_uncompress(m0)
+ struct mbuf *m0;
+{
+ register u_char cp, nextcp, *ip, *op;
+ register struct mbuf *m, *om;
+ struct mbuf *retm, **mp;
+ int i, j, noteof, clget, ileft, oleft, olen;
+
+ m = m0;
+ if (m->m_pkthdr.len < 6)
+ return (m0);
+ if (m->m_pkthdr.len >= MINCLSIZE)
+ clget = 1;
+ else
+ clget = 0;
+ MGETHDR(om, MT_DATA, M_WAIT);
+ if (clget)
+ MCLGET(om, M_WAIT);
+ olen = om->m_len = 8;
+ oleft = M_TRAILINGSPACE(om);
+ op = mtod(om, u_char *);
+ retm = om;
+ mp = &om->m_next;
+ if (m->m_len >= 6) {
+ ileft = m->m_len - 6;
+ ip = mtod(m, u_char *);
+ *((u_long *)op) = *((u_long *)ip);
+ bzero(op + 4, 3);
+ ip += 4;
+ op += 7;
+ if (*ip == '\0') {
+ m_freem(om);
+ return (m0);
+ }
+ *op++ = *ip++ - 1;
+ cp = *ip++;
+ } else {
+ ileft = m->m_len;
+ ip = mtod(m, u_char *);
+ nfscget(*op++);
+ nfscget(*op++);
+ nfscget(*op++);
+ nfscget(*op++);
+ bzero(op, 3);
+ op += 3;
+ nfscget(*op);
+ if (*op == '\0') {
+ m_freem(om);
+ return (m0);
+ }
+ (*op)--;
+ op++;
+ nfscget(cp);
+ }
+ noteof = 1;
+ while (noteof) {
+ if ((cp & NFSCRL) == NFSCRL) {
+ nfscget(nextcp);
+ if (cp == nextcp) {
+ nfscput(cp);
+ goto readit;
+ } else {
+ i = (cp & 0xf) + 2;
+ for (j = 0; j < i; j++) {
+ nfscput('\0');
+ }
+ cp = nextcp;
+ }
+ } else {
+ nfscput(cp);
+readit:
+ nfscget(cp);
+ }
+ }
+ m_freem(m0);
+ if (i = (olen & 0x3)) {
+ olen -= i;
+ om->m_len -= i;
+ }
+ retm->m_pkthdr.len = olen;
+ return (retm);
+}
projects / unix-history / commitdiff