date and time created 85/03/01 10:42:09 by ralph

SCCS-vsn: lib/libc/net/res_comp.c 4.1

diff --git a/usr/src/lib/libc/net/res_comp.c b/usr/src/lib/libc/net/res_comp.c
new file mode 100644 (file)
index 0000000..1084210
--- /dev/null
+++ b/usr/src/lib/libc/net/res_comp.c
@@ -0,0 +1,195 @@
+#ifndef lint
+static char sccsid[] = "@(#)res_comp.c 4.1 (Berkeley) %G%";
+#endif
+
+#include <sys/types.h>
+#include <stdio.h>
+#include <ctype.h>
+#include <nameser.h>
+
+
+/*
+ * Expand compressed domain name format to full domain name.
+ * Return size of compressed name or -1 if there was an error.
+ */
+dn_expand(msg, comp_dn, exp_dn, length)
+       char *msg, *comp_dn, *exp_dn;
+       int length;
+{
+       register char *cp, *dn;
+       register int n, c;
+       char *eom;
+       int len = 0;
+
+       dn = exp_dn;
+       cp = comp_dn;
+       eom = exp_dn + length - 1;
+       /*
+        * fetch next label in domain name
+        */
+       while (n = *cp++) {
+               /*
+                * Check for indirection
+                */
+               switch (n & INDIR_MASK) {
+               case 0:
+                       if (dn != exp_dn)
+                               *dn++ = '.';
+                       if (dn+n >= eom)
+                               return (-1);
+                       while (--n >= 0)
+                               if (islower(c = *cp++))
+                                       *dn++ = toupper(c);
+                               else
+                                       *dn++ = c;
+                       break;
+
+               case INDIR_MASK:
+                       if (len == 0)
+                               len = cp - comp_dn + 1;
+                       cp = msg + (((n & 0x3f) << 8) | (*cp & 0xff));
+                       break;
+
+               default:
+                       return (-1);                    /* flag error */
+               }
+       }
+       *dn = '\0';
+       if (len == 0)
+               len = cp - comp_dn;
+       return (len);
+}
+
+/*
+ * Compress domain name. Return the size of the compressed name or -1.
+ * Dnptrs is a list of pointers to previous compressed names. dnptrs[0]
+ * is a pointer to the beginning of the message. The list ends with NULL.
+ */
+dn_comp(exp_dn, comp_dn, length, dnptrs, lastdnptr)
+       char *exp_dn, *comp_dn;
+       int length;
+       char **dnptrs, **lastdnptr;
+{
+       register char *cp, *dn;
+       register int c, l;
+       char **cpp, **lpp, *sp, *eob;
+       char *msg;
+
+       dn = exp_dn;
+       cp = comp_dn;
+       eob = comp_dn + length;
+       if (dnptrs != NULL) {
+               if ((msg = *dnptrs++) != NULL) {
+                       for (cpp = dnptrs; *cpp != NULL; cpp++)
+                               ;
+                       lpp = cpp;      /* end of list to search */
+               }
+       } else
+               msg = NULL;
+       for (c = *dn++; c != '\0'; ) {
+               /* look to see if we can use pointers */
+               if (msg != NULL) {
+                       if ((l = dn_find(dn-1, msg, dnptrs, lpp)) >= 0) {
+                               if (cp+1 >= eob)
+                                       return (-1);
+                               *cp++ = (l >> 8) | INDIR_MASK;
+                               *cp++ = l;
+                               return (cp - comp_dn);
+                       }
+                       /* not found, save it */
+                       if (lastdnptr != NULL && cpp < lastdnptr-1) {
+                               *cpp++ = cp;
+                               *cpp = NULL;
+                       }
+               }
+               sp = cp++;      /* save ptr to length byte */
+               do {
+                       if (c == '.') {
+                               c = *dn++;
+                               break;
+                       }
+                       if (cp >= eob)
+                               return (-1);
+                       *cp++ = c;
+               } while ((c = *dn++) != '\0');
+               if ((l = cp - sp - 1) <= 0 || l > MAXLABEL)
+                       return (-1);
+               *sp = l;
+       }
+       if (cp >= eob)
+               return (-1);
+       *cp++ = '\0';
+       return (cp - comp_dn);
+}
+
+/*
+ * Skip over a compressed domain name. Return the size.
+ */
+dn_skip(buf)
+       char *buf;
+{
+       register char *cp;
+       register int n;
+
+       cp = buf;
+       while (n = *cp++) {
+               /*
+                * check for indirection
+                */
+               switch (n & INDIR_MASK) {
+               case 0:         /* normal case, n == len */
+                       cp += n;
+                       continue;
+               default:        /* illegal type */
+                       return (-1);
+               case INDIR_MASK:        /* indirection */
+                       cp++;
+               }
+               break;
+       }
+       return (cp - buf);
+}
+
+/*
+ * Search for expanded name from a list of previously compressed names.
+ * Return the offset from msg if found or -1.
+ */
+dn_find(exp_dn, msg, dnptrs, lastdnptr)
+       char *exp_dn, *msg;
+       char **dnptrs, **lastdnptr;
+{
+       register char *dn, *cp, **cpp;
+       register int n;
+       char *sp;
+
+       for (cpp = dnptrs; cpp < lastdnptr; cpp++) {
+               dn = exp_dn;
+               sp = cp = *cpp;
+               while (n = *cp++) {
+                       /*
+                        * check for indirection
+                        */
+                       switch (n & INDIR_MASK) {
+                       case 0:         /* normal case, n == len */
+                               while (--n >= 0)
+                                       if (*dn++ != *cp++)
+                                               goto next;
+                               if ((n = *dn++) == '\0' && *cp == '\0')
+                                       return (sp - msg);
+                               if (n == '.')
+                                       continue;
+                               goto next;
+
+                       default:        /* illegal type */
+                               return (-1);
+
+                       case INDIR_MASK:        /* indirection */
+                               cp = msg + (((n & 0x3f) << 8) | (*cp & 0xff));
+                       }
+               }
+               if (*dn == '\0')
+                       return (sp - msg);
+       next:   ;
+       }
+       return (-1);
+}