/* * Copyright (c) 1990, 1991, 1993, 1994, 1995, 1996, 1997 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that: (1) source code distributions * retain the above copyright notice and this paragraph in its entirety, (2) * distributions including binary code include the above copyright notice and * this paragraph in its entirety in the documentation or other materials * provided with the distribution, and (3) all advertising materials mentioning * features or use of this software display the following acknowledgement: * ``This product includes software developed by the University of California, * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of * the University nor the names of its contributors may be used to endorse * or promote products derived from this software without specific prior * written permission. * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. * * Format and print bootp packets. */ #ifndef lint static const char rcsid[] _U_ = "@(#) $Header: /tcpdump/master/tcpdump/print-bootp.c,v 1.78.2.9 2007/08/21 22:02:08 guy Exp $ (LBL)"; #endif #ifdef HAVE_CONFIG_H #include "config.h" #endif #include <tcpdump-stdinc.h> #include <stdio.h> #include <string.h> #include "interface.h" #include "addrtoname.h" #include "extract.h" #include "ether.h" #include "bootp.h" static void rfc1048_print(const u_char *); static void cmu_print(const u_char *); static char *client_fqdn_flags(u_int flags); static char tstr[] = " [|bootp]"; static const struct tok bootp_flag_values[] = { { 0x8000, "Broadcast" }, { 0, NULL} }; static const struct tok bootp_op_values[] = { { BOOTPREQUEST, "Request" }, { BOOTPREPLY, "Reply" }, { 0, NULL} }; /* * Print bootp requests */ void bootp_print(register const u_char *cp, u_int length) { register const struct bootp *bp; static const u_char vm_cmu[4] = VM_CMU; static const u_char vm_rfc1048[4] = VM_RFC1048; bp = (const struct bootp *)cp; TCHECK(bp->bp_op); printf("BOOTP/DHCP, %s", tok2str(bootp_op_values, "unknown (0x%02x)", bp->bp_op)); if (bp->bp_htype == 1 && bp->bp_hlen == 6 && bp->bp_op == BOOTPREQUEST) { TCHECK2(bp->bp_chaddr[0], 6); printf(" from %s", etheraddr_string(bp->bp_chaddr)); } printf(", length %u", length); if (!vflag) return; TCHECK(bp->bp_secs); /* The usual hardware address type is 1 (10Mb Ethernet) */ if (bp->bp_htype != 1) printf(", htype %d", bp->bp_htype); /* The usual length for 10Mb Ethernet address is 6 bytes */ if (bp->bp_htype != 1 || bp->bp_hlen != 6) printf(", hlen %d", bp->bp_hlen); /* Only print interesting fields */ if (bp->bp_hops) printf(", hops %d", bp->bp_hops); if (bp->bp_xid) printf(", xid 0x%x", EXTRACT_32BITS(&bp->bp_xid)); if (bp->bp_secs) printf(", secs %d", EXTRACT_16BITS(&bp->bp_secs)); printf(", Flags [%s]", bittok2str(bootp_flag_values, "none", EXTRACT_16BITS(&bp->bp_flags))); if (vflag > 1) printf(" (0x%04x)", EXTRACT_16BITS(&bp->bp_flags)); /* Client's ip address */ TCHECK(bp->bp_ciaddr); if (bp->bp_ciaddr.s_addr) printf("\n\t Client-IP %s", ipaddr_string(&bp->bp_ciaddr)); /* 'your' ip address (bootp client) */ TCHECK(bp->bp_yiaddr); if (bp->bp_yiaddr.s_addr) printf("\n\t Your-IP %s", ipaddr_string(&bp->bp_yiaddr)); /* Server's ip address */ TCHECK(bp->bp_siaddr); if (bp->bp_siaddr.s_addr) printf("\n\t Server-IP %s", ipaddr_string(&bp->bp_siaddr)); /* Gateway's ip address */ TCHECK(bp->bp_giaddr); if (bp->bp_giaddr.s_addr) printf("\n\t Gateway-IP %s", ipaddr_string(&bp->bp_giaddr)); /* Client's Ethernet address */ if (bp->bp_htype == 1 && bp->bp_hlen == 6) { TCHECK2(bp->bp_chaddr[0], 6); printf("\n\t Client-Ethernet-Address %s", etheraddr_string(bp->bp_chaddr)); } TCHECK2(bp->bp_sname[0], 1); /* check first char only */ if (*bp->bp_sname) { printf("\n\t sname \""); if (fn_print(bp->bp_sname, snapend)) { putchar('"'); fputs(tstr + 1, stdout); return; } putchar('"'); } TCHECK2(bp->bp_file[0], 1); /* check first char only */ if (*bp->bp_file) { printf("\n\t file \""); if (fn_print(bp->bp_file, snapend)) { putchar('"'); fputs(tstr + 1, stdout); return; } putchar('"'); } /* Decode the vendor buffer */ TCHECK(bp->bp_vend[0]); if (memcmp((const char *)bp->bp_vend, vm_rfc1048, sizeof(u_int32_t)) == 0) rfc1048_print(bp->bp_vend); else if (memcmp((const char *)bp->bp_vend, vm_cmu, sizeof(u_int32_t)) == 0) cmu_print(bp->bp_vend); else { u_int32_t ul; ul = EXTRACT_32BITS(&bp->bp_vend); if (ul != 0) printf("\n\t Vendor-#0x%x", ul); } return; trunc: fputs(tstr, stdout); } /* * The first character specifies the format to print: * i - ip address (32 bits) * p - ip address pairs (32 bits + 32 bits) * l - long (32 bits) * L - unsigned long (32 bits) * s - short (16 bits) * b - period-seperated decimal bytes (variable length) * x - colon-seperated hex bytes (variable length) * a - ascii string (variable length) * B - on/off (8 bits) * $ - special (explicit code to handle) */ static struct tok tag2str[] = { /* RFC1048 tags */ { TAG_PAD, " PAD" }, { TAG_SUBNET_MASK, "iSubnet-Mask" }, /* subnet mask (RFC950) */ { TAG_TIME_OFFSET, "LTime-Zone" }, /* seconds from UTC */ { TAG_GATEWAY, "iDefault-Gateway" }, /* default gateway */ { TAG_TIME_SERVER, "iTime-Server" }, /* time servers (RFC868) */ { TAG_NAME_SERVER, "iIEN-Name-Server" }, /* IEN name servers (IEN116) */ { TAG_DOMAIN_SERVER, "iDomain-Name-Server" }, /* domain name (RFC1035) */ { TAG_LOG_SERVER, "iLOG" }, /* MIT log servers */ { TAG_COOKIE_SERVER, "iCS" }, /* cookie servers (RFC865) */ { TAG_LPR_SERVER, "iLPR-Server" }, /* lpr server (RFC1179) */ { TAG_IMPRESS_SERVER, "iIM" }, /* impress servers (Imagen) */ { TAG_RLP_SERVER, "iRL" }, /* resource location (RFC887) */ { TAG_HOSTNAME, "aHostname" }, /* ascii hostname */ { TAG_BOOTSIZE, "sBS" }, /* 512 byte blocks */ { TAG_END, " END" }, /* RFC1497 tags */ { TAG_DUMPPATH, "aDP" }, { TAG_DOMAINNAME, "aDomain-Name" }, { TAG_SWAP_SERVER, "iSS" }, { TAG_ROOTPATH, "aRP" }, { TAG_EXTPATH, "aEP" }, /* RFC2132 tags */ { TAG_IP_FORWARD, "BIPF" }, { TAG_NL_SRCRT, "BSRT" }, { TAG_PFILTERS, "pPF" }, { TAG_REASS_SIZE, "sRSZ" }, { TAG_DEF_TTL, "bTTL" }, { TAG_MTU_TIMEOUT, "lMTU-Timeout" }, { TAG_MTU_TABLE, "sMTU-Table" }, { TAG_INT_MTU, "sMTU" }, { TAG_LOCAL_SUBNETS, "BLSN" }, { TAG_BROAD_ADDR, "iBR" }, { TAG_DO_MASK_DISC, "BMD" }, { TAG_SUPPLY_MASK, "BMS" }, { TAG_DO_RDISC, "BRouter-Discovery" }, { TAG_RTR_SOL_ADDR, "iRSA" }, { TAG_STATIC_ROUTE, "pStatic-Route" }, { TAG_USE_TRAILERS, "BUT" }, { TAG_ARP_TIMEOUT, "lAT" }, { TAG_ETH_ENCAP, "BIE" }, { TAG_TCP_TTL, "bTT" }, { TAG_TCP_KEEPALIVE, "lKI" }, { TAG_KEEPALIVE_GO, "BKG" }, { TAG_NIS_DOMAIN, "aYD" }, { TAG_NIS_SERVERS, "iYS" }, { TAG_NTP_SERVERS, "iNTP" }, { TAG_VENDOR_OPTS, "bVendor-Option" }, { TAG_NETBIOS_NS, "iNetbios-Name-Server" }, { TAG_NETBIOS_DDS, "iWDD" }, { TAG_NETBIOS_NODE, "$Netbios-Node" }, { TAG_NETBIOS_SCOPE, "aNetbios-Scope" }, { TAG_XWIN_FS, "iXFS" }, { TAG_XWIN_DM, "iXDM" }, { TAG_NIS_P_DOMAIN, "sN+D" }, { TAG_NIS_P_SERVERS, "iN+S" }, { TAG_MOBILE_HOME, "iMH" }, { TAG_SMPT_SERVER, "iSMTP" }, { TAG_POP3_SERVER, "iPOP3" }, { TAG_NNTP_SERVER, "iNNTP" }, { TAG_WWW_SERVER, "iWWW" }, { TAG_FINGER_SERVER, "iFG" }, { TAG_IRC_SERVER, "iIRC" }, { TAG_STREETTALK_SRVR, "iSTS" }, { TAG_STREETTALK_STDA, "iSTDA" }, { TAG_REQUESTED_IP, "iRequested-IP" }, { TAG_IP_LEASE, "lLease-Time" }, { TAG_OPT_OVERLOAD, "$OO" }, { TAG_TFTP_SERVER, "aTFTP" }, { TAG_BOOTFILENAME, "aBF" }, { TAG_DHCP_MESSAGE, " DHCP-Message" }, { TAG_SERVER_ID, "iServer-ID" }, { TAG_PARM_REQUEST, "bParameter-Request" }, { TAG_MESSAGE, "aMSG" }, { TAG_MAX_MSG_SIZE, "sMSZ" }, { TAG_RENEWAL_TIME, "lRN" }, { TAG_REBIND_TIME, "lRB" }, { TAG_VENDOR_CLASS, "aVendor-Class" }, { TAG_CLIENT_ID, "$Client-ID" }, /* RFC 2485 */ { TAG_OPEN_GROUP_UAP, "aUAP" }, /* RFC 2563 */ { TAG_DISABLE_AUTOCONF, "BNOAUTO" }, /* RFC 2610 */ { TAG_SLP_DA, "bSLP-DA" }, /*"b" is a little wrong */ { TAG_SLP_SCOPE, "bSLP-SCOPE" }, /*"b" is a little wrong */ /* RFC 2937 */ { TAG_NS_SEARCH, "sNSSEARCH" }, /* XXX 's' */ /* RFC 3011 */ { TAG_IP4_SUBNET_SELECT, "iSUBNET" }, /* RFC 3442 */ { TAG_CLASSLESS_STATIC_RT, "$Classless-Static-Route" }, { TAG_CLASSLESS_STA_RT_MS, "$Classless-Static-Route-Microsoft" }, /* http://www.iana.org/assignments/bootp-dhcp-extensions/index.htm */ { TAG_USER_CLASS, "aCLASS" }, { TAG_SLP_NAMING_AUTH, "aSLP-NA" }, { TAG_CLIENT_FQDN, "$FQDN" }, { TAG_AGENT_CIRCUIT, "$Agent-Information" }, { TAG_AGENT_REMOTE, "bARMT" }, { TAG_AGENT_MASK, "bAMSK" }, { TAG_TZ_STRING, "aTZSTR" }, { TAG_FQDN_OPTION, "bFQDNS" }, /* XXX 'b' */ { TAG_AUTH, "bAUTH" }, /* XXX 'b' */ { TAG_VINES_SERVERS, "iVINES" }, { TAG_SERVER_RANK, "sRANK" }, { TAG_CLIENT_ARCH, "sARCH" }, { TAG_CLIENT_NDI, "bNDI" }, /* XXX 'b' */ { TAG_CLIENT_GUID, "bGUID" }, /* XXX 'b' */ { TAG_LDAP_URL, "aLDAP" }, { TAG_6OVER4, "i6o4" }, { TAG_PRINTER_NAME, "aPRTR" }, { TAG_MDHCP_SERVER, "bMDHCP" }, /* XXX 'b' */ { TAG_IPX_COMPAT, "bIPX" }, /* XXX 'b' */ { TAG_NETINFO_PARENT, "iNI" }, { TAG_NETINFO_PARENT_TAG, "aNITAG" }, { TAG_URL, "aURL" }, { TAG_FAILOVER, "bFAIL" }, /* XXX 'b' */ { 0, NULL } }; /* 2-byte extended tags */ static struct tok xtag2str[] = { { 0, NULL } }; /* DHCP "options overload" types */ static struct tok oo2str[] = { { 1, "file" }, { 2, "sname" }, { 3, "file+sname" }, { 0, NULL } }; /* NETBIOS over TCP/IP node type options */ static struct tok nbo2str[] = { { 0x1, "b-node" }, { 0x2, "p-node" }, { 0x4, "m-node" }, { 0x8, "h-node" }, { 0, NULL } }; /* ARP Hardware types, for Client-ID option */ static struct tok arp2str[] = { { 0x1, "ether" }, { 0x6, "ieee802" }, { 0x7, "arcnet" }, { 0xf, "frelay" }, { 0x17, "strip" }, { 0x18, "ieee1394" }, { 0, NULL } }; static struct tok dhcp_msg_values[] = { { DHCPDISCOVER, "Discover" }, { DHCPOFFER, "Offer" }, { DHCPREQUEST, "Request" }, { DHCPDECLINE, "Decline" }, { DHCPACK, "ACK" }, { DHCPNAK, "NACK" }, { DHCPRELEASE, "Release" }, { DHCPINFORM, "Inform" }, { 0, NULL } }; #define AGENT_SUBOPTION_CIRCUIT_ID 1 static struct tok agent_suboption_values[] = { { AGENT_SUBOPTION_CIRCUIT_ID, "Circuit-ID" }, { 0, NULL } }; static void rfc1048_print(register const u_char *bp) { register u_int16_t tag; register u_int len; register const char *cp; register char c; int first, idx; u_int32_t ul; u_int16_t us; u_int8_t uc, subopt, suboptlen; printf("\n\t Vendor-rfc1048 Extensions"); /* Step over magic cookie */ printf("\n\t Magic Cookie 0x%08x", EXTRACT_32BITS(bp)); bp += sizeof(int32_t); /* Loop while we there is a tag left in the buffer */ while (TTEST2(*bp, 1)) { tag = *bp++; if (tag == TAG_PAD && vflag < 3) continue; if (tag == TAG_END && vflag < 3) return; if (tag == TAG_EXTENDED_OPTION) { TCHECK2(*(bp + 1), 2); tag = EXTRACT_16BITS(bp + 1); /* XXX we don't know yet if the IANA will * preclude overlap of 1-byte and 2-byte spaces. * If not, we need to offset tag after this step. */ cp = tok2str(xtag2str, "?xT%u", tag); } else cp = tok2str(tag2str, "?T%u", tag); c = *cp++; if (tag == TAG_PAD || tag == TAG_END) len = 0; else { /* Get the length; check for truncation */ TCHECK2(*bp, 1); len = *bp++; } printf("\n\t %s Option %u, length %u%s", cp, tag, len, len > 0 ? ": " : ""); if (tag == TAG_PAD && vflag > 2) { u_int ntag = 1; while (TTEST2(*bp, 1) && *bp == TAG_PAD) { bp++; ntag++; } if (ntag > 1) printf(", occurs %u", ntag); } if (!TTEST2(*bp, len)) { printf("[|rfc1048 %u]", len); return; } if (tag == TAG_DHCP_MESSAGE && len == 1) { uc = *bp++; printf("%s", tok2str(dhcp_msg_values, "Unknown (%u)", uc)); continue; } if (tag == TAG_PARM_REQUEST) { idx = 0; while (len-- > 0) { uc = *bp++; cp = tok2str(tag2str, "?Option %u", uc); if (idx % 4 == 0) printf("\n\t "); else printf(", "); printf("%s", cp + 1); idx++; } continue; } if (tag == TAG_EXTENDED_REQUEST) { first = 1; while (len > 1) { len -= 2; us = EXTRACT_16BITS(bp); bp += 2; cp = tok2str(xtag2str, "?xT%u", us); if (!first) putchar('+'); printf("%s", cp + 1); first = 0; } continue; } /* Print data */ if (c == '?') { /* Base default formats for unknown tags on data size */ if (len & 1) c = 'b'; else if (len & 2) c = 's'; else c = 'l'; } first = 1; switch (c) { case 'a': /* ascii strings */ putchar('"'); if (fn_printn(bp, len, snapend)) { putchar('"'); goto trunc; } putchar('"'); bp += len; len = 0; break; case 'i': case 'l': case 'L': /* ip addresses/32-bit words */ while (len >= sizeof(ul)) { if (!first) putchar(','); ul = EXTRACT_32BITS(bp); if (c == 'i') { ul = htonl(ul); printf("%s", ipaddr_string(&ul)); } else if (c == 'L') printf("%d", ul); else printf("%u", ul); bp += sizeof(ul); len -= sizeof(ul); first = 0; } break; case 'p': /* IP address pairs */ while (len >= 2*sizeof(ul)) { if (!first) putchar(','); memcpy((char *)&ul, (const char *)bp, sizeof(ul)); printf("(%s:", ipaddr_string(&ul)); bp += sizeof(ul); memcpy((char *)&ul, (const char *)bp, sizeof(ul)); printf("%s)", ipaddr_string(&ul)); bp += sizeof(ul); len -= 2*sizeof(ul); first = 0; } break; case 's': /* shorts */ while (len >= sizeof(us)) { if (!first) putchar(','); us = EXTRACT_16BITS(bp); printf("%u", us); bp += sizeof(us); len -= sizeof(us); first = 0; } break; case 'B': /* boolean */ while (len > 0) { if (!first) putchar(','); switch (*bp) { case 0: putchar('N'); break; case 1: putchar('Y'); break; default: printf("%u?", *bp); break; } ++bp; --len; first = 0; } break; case 'b': case 'x': default: /* Bytes */ while (len > 0) { if (!first) putchar(c == 'x' ? ':' : '.'); if (c == 'x') printf("%02x", *bp); else printf("%u", *bp); ++bp; --len; first = 0; } break; case '$': /* Guys we can't handle with one of the usual cases */ switch (tag) { case TAG_NETBIOS_NODE: /* this option should be at least 1 byte long */ if (len < 1) { printf("ERROR: option %u len %u < 1 bytes", TAG_NETBIOS_NODE, len); bp += len; len = 0; break; } tag = *bp++; --len; fputs(tok2str(nbo2str, NULL, tag), stdout); break; case TAG_OPT_OVERLOAD: /* this option should be at least 1 byte long */ if (len < 1) { printf("ERROR: option %u len %u < 1 bytes", TAG_OPT_OVERLOAD, len); bp += len; len = 0; break; } tag = *bp++; --len; fputs(tok2str(oo2str, NULL, tag), stdout); break; case TAG_CLIENT_FQDN: /* this option should be at least 3 bytes long */ if (len < 3) { printf("ERROR: option %u len %u < 3 bytes", TAG_CLIENT_FQDN, len); bp += len; len = 0; break; } if (*bp) printf("[%s] ", client_fqdn_flags(*bp)); bp++; if (*bp || *(bp+1)) printf("%u/%u ", *bp, *(bp+1)); bp += 2; putchar('"'); if (fn_printn(bp, len - 3, snapend)) { putchar('"'); goto trunc; } putchar('"'); bp += len - 3; len = 0; break; case TAG_CLIENT_ID: { int type; /* this option should be at least 1 byte long */ if (len < 1) { printf("ERROR: option %u len %u < 1 bytes", TAG_CLIENT_ID, len); bp += len; len = 0; break; } type = *bp++; len--; if (type == 0) { putchar('"'); if (fn_printn(bp, len, snapend)) { putchar('"'); goto trunc; } putchar('"'); bp += len; len = 0; break; } else { printf("%s ", tok2str(arp2str, "hardware-type %u,", type)); while (len > 0) { if (!first) putchar(':'); printf("%02x", *bp); ++bp; --len; first = 0; } } break; } case TAG_AGENT_CIRCUIT: while (len >= 2) { subopt = *bp++; suboptlen = *bp++; len -= 2; if (suboptlen > len) { printf("\n\t %s SubOption %u, length %u: length goes past end of option", tok2str(agent_suboption_values, "Unknown", subopt), subopt, suboptlen); bp += len; len = 0; break; } printf("\n\t %s SubOption %u, length %u: ", tok2str(agent_suboption_values, "Unknown", subopt), subopt, suboptlen); switch (subopt) { case AGENT_SUBOPTION_CIRCUIT_ID: fn_printn(bp, suboptlen, NULL); break; default: print_unknown_data(bp, "\n\t\t", suboptlen); } len -= suboptlen; bp += suboptlen; } break; case TAG_CLASSLESS_STATIC_RT: case TAG_CLASSLESS_STA_RT_MS: { u_int mask_width, significant_octets, i; /* this option should be at least 5 bytes long */ if (len < 5) { printf("ERROR: option %u len %u < 5 bytes", TAG_CLASSLESS_STATIC_RT, len); bp += len; len = 0; break; } while (len > 0) { if (!first) putchar(','); mask_width = *bp++; len--; /* mask_width <= 32 */ if (mask_width > 32) { printf("[ERROR: Mask width (%d) > 32]", mask_width); bp += len; len = 0; break; } significant_octets = (mask_width + 7) / 8; /* significant octets + router(4) */ if (len < significant_octets + 4) { printf("[ERROR: Remaining length (%u) < %u bytes]", len, significant_octets + 4); bp += len; len = 0; break; } putchar('('); if (mask_width == 0) printf("default"); else { for (i = 0; i < significant_octets ; i++) { if (i > 0) putchar('.'); printf("%d", *bp++); } for (i = significant_octets ; i < 4 ; i++) printf(".0"); printf("/%d", mask_width); } memcpy((char *)&ul, (const char *)bp, sizeof(ul)); printf(":%s)", ipaddr_string(&ul)); bp += sizeof(ul); len -= (significant_octets + 4); first = 0; } } break; default: printf("[unknown special tag %u, size %u]", tag, len); bp += len; len = 0; break; } break; } /* Data left over? */ if (len) { printf("\n\t trailing data length %u", len); bp += len; } } return; trunc: printf("|[rfc1048]"); } static void cmu_print(register const u_char *bp) { register const struct cmu_vend *cmu; #define PRINTCMUADDR(m, s) { TCHECK(cmu->m); \ if (cmu->m.s_addr != 0) \ printf(" %s:%s", s, ipaddr_string(&cmu->m.s_addr)); } printf(" vend-cmu"); cmu = (const struct cmu_vend *)bp; /* Only print if there are unknown bits */ TCHECK(cmu->v_flags); if ((cmu->v_flags & ~(VF_SMASK)) != 0) printf(" F:0x%x", cmu->v_flags); PRINTCMUADDR(v_dgate, "DG"); PRINTCMUADDR(v_smask, cmu->v_flags & VF_SMASK ? "SM" : "SM*"); PRINTCMUADDR(v_dns1, "NS1"); PRINTCMUADDR(v_dns2, "NS2"); PRINTCMUADDR(v_ins1, "IEN1"); PRINTCMUADDR(v_ins2, "IEN2"); PRINTCMUADDR(v_ts1, "TS1"); PRINTCMUADDR(v_ts2, "TS2"); return; trunc: fputs(tstr, stdout); #undef PRINTCMUADDR } static char * client_fqdn_flags(u_int flags) { static char buf[8+1]; int i = 0; if (flags & CLIENT_FQDN_FLAGS_S) buf[i++] = 'S'; if (flags & CLIENT_FQDN_FLAGS_O) buf[i++] = 'O'; if (flags & CLIENT_FQDN_FLAGS_E) buf[i++] = 'E'; if (flags & CLIENT_FQDN_FLAGS_N) buf[i++] = 'N'; buf[i] = '\0'; return buf; }