118546Sralph /* 221384Sdist * Copyright (c) 1985 Regents of the University of California. 333679Sbostic * All rights reserved. 433679Sbostic * 533679Sbostic * Redistribution and use in source and binary forms are permitted 633679Sbostic * provided that this notice is preserved and that due credit is given 733679Sbostic * to the University of California at Berkeley. The name of the University 833679Sbostic * may not be used to endorse or promote products derived from this 933679Sbostic * software without specific prior written permission. This software 1033679Sbostic * is provided ``as is'' without express or implied warranty. 1118546Sralph */ 1218546Sralph 1326631Sdonn #if defined(LIBC_SCCS) && !defined(lint) 14*33727Sbostic static char sccsid[] = "@(#)res_comp.c 6.13 (Berkeley) 03/13/88"; 1533679Sbostic #endif /* LIBC_SCCS and not lint */ 1621384Sdist 1718140Sralph #include <sys/types.h> 1818140Sralph #include <stdio.h> 1924079Skjd #include <arpa/nameser.h> 2018140Sralph 2123870Skjd 2218140Sralph /* 2318342Sralph * Expand compressed domain name 'comp_dn' to full domain name. 2418342Sralph * 'msg' is a pointer to the begining of the message, 2526112Skarels * 'eomorig' points to the first location after the message, 2618342Sralph * 'exp_dn' is a pointer to a buffer of size 'length' for the result. 2718140Sralph * Return size of compressed name or -1 if there was an error. 2818140Sralph */ 2926112Skarels dn_expand(msg, eomorig, comp_dn, exp_dn, length) 3032647Skarels u_char *msg, *eomorig, *comp_dn, *exp_dn; 3126112Skarels int length; 3218140Sralph { 3332647Skarels register u_char *cp, *dn; 3418140Sralph register int n, c; 3532647Skarels u_char *eom; 3631686Skarels int len = -1, checked = 0; 3718140Sralph 3818140Sralph dn = exp_dn; 3918140Sralph cp = comp_dn; 4018140Sralph eom = exp_dn + length - 1; 4118140Sralph /* 4218140Sralph * fetch next label in domain name 4318140Sralph */ 4418140Sralph while (n = *cp++) { 4518140Sralph /* 4618140Sralph * Check for indirection 4718140Sralph */ 4818140Sralph switch (n & INDIR_MASK) { 4918140Sralph case 0: 5018342Sralph if (dn != exp_dn) { 5118342Sralph if (dn >= eom) 5218342Sralph return (-1); 5318140Sralph *dn++ = '.'; 5418342Sralph } 5518140Sralph if (dn+n >= eom) 5618140Sralph return (-1); 5731686Skarels checked += n + 1; 5826064Skjd while (--n >= 0) { 5926812Sbloom if ((c = *cp++) == '.') { 6026812Sbloom if (dn+n+1 >= eom) 6126812Sbloom return (-1); 6226812Sbloom *dn++ = '\\'; 6318342Sralph } 6426812Sbloom *dn++ = c; 6526112Skarels if (cp >= eomorig) /* out of range */ 6626064Skjd return(-1); 6726064Skjd } 6818140Sralph break; 6918140Sralph 7018140Sralph case INDIR_MASK: 7118342Sralph if (len < 0) 7218140Sralph len = cp - comp_dn + 1; 7318140Sralph cp = msg + (((n & 0x3f) << 8) | (*cp & 0xff)); 7426112Skarels if (cp < msg || cp >= eomorig) /* out of range */ 7526064Skjd return(-1); 7631686Skarels checked += 2; 7731686Skarels /* 7831686Skarels * Check for loops in the compressed name; 7931686Skarels * if we've looked at the whole message, 8031686Skarels * there must be a loop. 8131686Skarels */ 8231686Skarels if (checked >= eomorig - msg) 8331686Skarels return (-1); 8418140Sralph break; 8518140Sralph 8618140Sralph default: 8718140Sralph return (-1); /* flag error */ 8818140Sralph } 8918140Sralph } 9018140Sralph *dn = '\0'; 9118342Sralph if (len < 0) 9218140Sralph len = cp - comp_dn; 9318140Sralph return (len); 9418140Sralph } 9518140Sralph 9618140Sralph /* 9718342Sralph * Compress domain name 'exp_dn' into 'comp_dn'. 9818342Sralph * Return the size of the compressed name or -1. 9918342Sralph * 'length' is the size of the array pointed to by 'comp_dn'. 10018342Sralph * 'dnptrs' is a list of pointers to previous compressed names. dnptrs[0] 10118140Sralph * is a pointer to the beginning of the message. The list ends with NULL. 10218342Sralph * 'lastdnptr' is a pointer to the end of the arrary pointed to 10318342Sralph * by 'dnptrs'. Side effect is to update the list of pointers for 10418342Sralph * labels inserted into the message as we compress the name. 10518342Sralph * If 'dnptr' is NULL, we don't try to compress names. If 'lastdnptr' 10618342Sralph * is NULL, we don't update the list. 10718140Sralph */ 10818140Sralph dn_comp(exp_dn, comp_dn, length, dnptrs, lastdnptr) 10932647Skarels u_char *exp_dn, *comp_dn; 11018140Sralph int length; 11132647Skarels u_char **dnptrs, **lastdnptr; 11218140Sralph { 11332647Skarels register u_char *cp, *dn; 11418140Sralph register int c, l; 11532647Skarels u_char **cpp, **lpp, *sp, *eob; 11632647Skarels u_char *msg; 11718140Sralph 11818140Sralph dn = exp_dn; 11918140Sralph cp = comp_dn; 12025360Sbloom eob = cp + length; 12118140Sralph if (dnptrs != NULL) { 12218140Sralph if ((msg = *dnptrs++) != NULL) { 12318140Sralph for (cpp = dnptrs; *cpp != NULL; cpp++) 12418140Sralph ; 12518140Sralph lpp = cpp; /* end of list to search */ 12618140Sralph } 12718140Sralph } else 12818140Sralph msg = NULL; 12918140Sralph for (c = *dn++; c != '\0'; ) { 13018140Sralph /* look to see if we can use pointers */ 13118140Sralph if (msg != NULL) { 13218140Sralph if ((l = dn_find(dn-1, msg, dnptrs, lpp)) >= 0) { 13318140Sralph if (cp+1 >= eob) 13418140Sralph return (-1); 13518140Sralph *cp++ = (l >> 8) | INDIR_MASK; 13626240Skjd *cp++ = l % 256; 13718140Sralph return (cp - comp_dn); 13818140Sralph } 13918140Sralph /* not found, save it */ 14018140Sralph if (lastdnptr != NULL && cpp < lastdnptr-1) { 14118140Sralph *cpp++ = cp; 14218140Sralph *cpp = NULL; 14318140Sralph } 14418140Sralph } 14518140Sralph sp = cp++; /* save ptr to length byte */ 14618140Sralph do { 14718140Sralph if (c == '.') { 14818140Sralph c = *dn++; 14918140Sralph break; 15018140Sralph } 15118342Sralph if (c == '\\') { 15218342Sralph if ((c = *dn++) == '\0') 15318342Sralph break; 15418342Sralph } 15518140Sralph if (cp >= eob) 15618140Sralph return (-1); 15718140Sralph *cp++ = c; 15818140Sralph } while ((c = *dn++) != '\0'); 15918342Sralph /* catch trailing '.'s but not '..' */ 16018342Sralph if ((l = cp - sp - 1) == 0 && c == '\0') { 16118342Sralph cp--; 16218342Sralph break; 16318342Sralph } 16418342Sralph if (l <= 0 || l > MAXLABEL) 16518140Sralph return (-1); 16618140Sralph *sp = l; 16718140Sralph } 16818140Sralph if (cp >= eob) 16918140Sralph return (-1); 17018140Sralph *cp++ = '\0'; 17118140Sralph return (cp - comp_dn); 17218140Sralph } 17318140Sralph 17418140Sralph /* 17518342Sralph * Skip over a compressed domain name. Return the size or -1. 17618140Sralph */ 17732647Skarels dn_skipname(comp_dn, eom) 17832647Skarels u_char *comp_dn, *eom; 17918140Sralph { 18032647Skarels register u_char *cp; 18118140Sralph register int n; 18218140Sralph 18318342Sralph cp = comp_dn; 18432647Skarels while (cp < eom && (n = *cp++)) { 18518140Sralph /* 18618140Sralph * check for indirection 18718140Sralph */ 18818140Sralph switch (n & INDIR_MASK) { 18918140Sralph case 0: /* normal case, n == len */ 19018140Sralph cp += n; 19118140Sralph continue; 19218140Sralph default: /* illegal type */ 19318140Sralph return (-1); 19418140Sralph case INDIR_MASK: /* indirection */ 19518140Sralph cp++; 19618140Sralph } 19718140Sralph break; 19818140Sralph } 19918342Sralph return (cp - comp_dn); 20018140Sralph } 20118140Sralph 20218140Sralph /* 20318140Sralph * Search for expanded name from a list of previously compressed names. 20418140Sralph * Return the offset from msg if found or -1. 20533617Skarels * dnptrs is the pointer to the first name on the list, 20633617Skarels * not the pointer to the start of the message. 20718140Sralph */ 20833617Skarels static 20918140Sralph dn_find(exp_dn, msg, dnptrs, lastdnptr) 21032647Skarels u_char *exp_dn, *msg; 21132647Skarels u_char **dnptrs, **lastdnptr; 21218140Sralph { 21332647Skarels register u_char *dn, *cp, **cpp; 21418140Sralph register int n; 21532647Skarels u_char *sp; 21618140Sralph 21733617Skarels for (cpp = dnptrs; cpp < lastdnptr; cpp++) { 21818140Sralph dn = exp_dn; 21918140Sralph sp = cp = *cpp; 22018140Sralph while (n = *cp++) { 22118140Sralph /* 22218140Sralph * check for indirection 22318140Sralph */ 22418140Sralph switch (n & INDIR_MASK) { 22518140Sralph case 0: /* normal case, n == len */ 22618342Sralph while (--n >= 0) { 22718342Sralph if (*dn == '\\') 22818342Sralph dn++; 22918140Sralph if (*dn++ != *cp++) 23018140Sralph goto next; 23118342Sralph } 23218140Sralph if ((n = *dn++) == '\0' && *cp == '\0') 23318140Sralph return (sp - msg); 23418140Sralph if (n == '.') 23518140Sralph continue; 23618140Sralph goto next; 23718140Sralph 23818140Sralph default: /* illegal type */ 23918140Sralph return (-1); 24018140Sralph 24118140Sralph case INDIR_MASK: /* indirection */ 24232647Skarels cp = msg + (((n & 0x3f) << 8) | *cp); 24318140Sralph } 24418140Sralph } 24518140Sralph if (*dn == '\0') 24618140Sralph return (sp - msg); 24718140Sralph next: ; 24818140Sralph } 24918140Sralph return (-1); 25018140Sralph } 25118528Sralph 25218528Sralph /* 25318528Sralph * Routines to insert/extract short/long's. Must account for byte 25418528Sralph * order and non-alignment problems. This code at least has the 25518528Sralph * advantage of being portable. 256*33727Sbostic * 257*33727Sbostic * used by sendmail. 25818528Sralph */ 25918528Sralph 26018528Sralph u_short 26130441Skjd _getshort(msgp) 26232647Skarels u_char *msgp; 26318528Sralph { 26418528Sralph register u_char *p = (u_char *) msgp; 26525360Sbloom #ifdef vax 26625360Sbloom /* 26725360Sbloom * vax compiler doesn't put shorts in registers 26825360Sbloom */ 26925360Sbloom register u_long u; 27025360Sbloom #else 27124735Sbloom register u_short u; 27225360Sbloom #endif 27318528Sralph 27424735Sbloom u = *p++ << 8; 27525360Sbloom return ((u_short)(u | *p)); 27618528Sralph } 27718528Sralph 27818528Sralph u_long 27930441Skjd _getlong(msgp) 28032647Skarels u_char *msgp; 28118528Sralph { 28218528Sralph register u_char *p = (u_char *) msgp; 28323870Skjd register u_long u; 28418528Sralph 28523870Skjd u = *p++; u <<= 8; 28623870Skjd u |= *p++; u <<= 8; 28723870Skjd u |= *p++; u <<= 8; 28823870Skjd return (u | *p); 28918528Sralph } 29018528Sralph 29123870Skjd 29218528Sralph putshort(s, msgp) 29318528Sralph register u_short s; 29432647Skarels register u_char *msgp; 29518528Sralph { 29618528Sralph 29718528Sralph msgp[1] = s; 29818528Sralph msgp[0] = s >> 8; 29918528Sralph } 30018528Sralph 30118528Sralph putlong(l, msgp) 30218528Sralph register u_long l; 30332647Skarels register u_char *msgp; 30418528Sralph { 30518528Sralph 30618528Sralph msgp[3] = l; 30718528Sralph msgp[2] = (l >>= 8); 30818528Sralph msgp[1] = (l >>= 8); 30918528Sralph msgp[0] = l >> 8; 31018528Sralph } 311