[14069] | 1 | /* Copyright 1994, 1999 by the Massachusetts Institute of Technology. |
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| 2 | * |
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| 3 | * Permission to use, copy, modify, and distribute this |
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| 4 | * software and its documentation for any purpose and without |
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| 5 | * fee is hereby granted, provided that the above copyright |
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| 6 | * notice appear in all copies and that both that copyright |
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| 7 | * notice and this permission notice appear in supporting |
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| 8 | * documentation, and that the name of M.I.T. not be used in |
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| 9 | * advertising or publicity pertaining to distribution of the |
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| 10 | * software without specific, written prior permission. |
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| 11 | * M.I.T. makes no representations about the suitability of |
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| 12 | * this software for any purpose. It is provided "as is" |
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| 13 | * without express or implied warranty. |
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| 14 | */ |
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[7779] | 15 | |
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[14069] | 16 | /* This is the server for the lert system. */ |
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[7779] | 17 | |
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[23654] | 18 | static const char rcsid[] = "$Id: lertsrv.c,v 1.10 2009/03/26 19:30:39 zacheiss Exp $"; |
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[7779] | 19 | |
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| 20 | #include <stdio.h> |
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[17860] | 21 | #include <unistd.h> |
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[23655] | 22 | #ifdef HAVE_KRB4 |
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[7779] | 23 | #include <krb.h> |
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[23655] | 24 | #include <des.h> |
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| 25 | #endif |
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[17860] | 26 | #include <krb5.h> |
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[7779] | 27 | #include <sys/types.h> |
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| 28 | #include <sys/stat.h> |
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| 29 | #include <fcntl.h> |
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| 30 | #include <sys/socket.h> |
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| 31 | #include <sys/uio.h> |
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| 32 | #include <netinet/in.h> |
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[22403] | 33 | #include <arpa/inet.h> |
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[7779] | 34 | #include <netdb.h> |
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| 35 | #include <sys/time.h> |
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| 36 | #include <hesiod.h> |
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[8859] | 37 | #include <string.h> |
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[7779] | 38 | #include <pwd.h> |
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| 39 | #include <sys/utsname.h> |
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[11791] | 40 | #include <errno.h> |
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[7779] | 41 | #include "lert.h" |
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| 42 | |
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[22403] | 43 | int get_user(char *pname, char *result, int onetime, char *ip); |
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[17860] | 44 | |
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| 45 | krb5_context context = NULL; |
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| 46 | |
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[14069] | 47 | int main(int argc, char **argv) |
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[7779] | 48 | { |
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| 49 | int s; /* The Socket */ |
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| 50 | struct sockaddr_in sin; |
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| 51 | struct sockaddr_in from; |
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| 52 | char packet[2048]; |
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[22403] | 53 | char *ip; |
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[19980] | 54 | char *username = NULL; |
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[7779] | 55 | int plen; |
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| 56 | char opacket[2048]; |
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| 57 | int fromlen; |
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| 58 | int status; |
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| 59 | int len; |
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[23655] | 60 | #ifdef HAVE_KRB4 |
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[7779] | 61 | AUTH_DAT ad; |
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| 62 | KTEXT_ST authent; |
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| 63 | KTEXT_ST ktxt; |
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[23655] | 64 | char instance[INST_SZ]; |
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[7779] | 65 | /* for krb_mk_priv */ |
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| 66 | des_key_schedule sched; /* session key schedule */ |
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[23655] | 67 | #endif |
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[7779] | 68 | struct hostent *hp; |
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| 69 | struct utsname thishost; |
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[17860] | 70 | /* for the krb5-authenticated v2 of the protocol */ |
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| 71 | krb5_error_code problem; |
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| 72 | krb5_auth_context auth_con = NULL; |
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| 73 | krb5_data auth, inbuf, outbuf; |
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| 74 | krb5_principal server = NULL, client = NULL; |
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| 75 | krb5_ticket *ticket; |
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| 76 | krb5_keytab keytab = NULL; |
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[7779] | 77 | |
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[17860] | 78 | ticket = NULL; |
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| 79 | memset(&outbuf, 0, sizeof(krb5_data)); |
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| 80 | |
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[7779] | 81 | #ifdef LOGGING |
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[14069] | 82 | setbuf(stdout, NULL); |
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[7779] | 83 | #endif |
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[14069] | 84 | |
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[7779] | 85 | s = socket(AF_INET, SOCK_DGRAM, 0); |
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| 86 | |
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[14069] | 87 | if (uname(&thishost) == -1) |
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| 88 | { |
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| 89 | fprintf(stderr, "%s: Unable to get system information: %s\n", |
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| 90 | argv[0], strerror(errno)); |
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| 91 | exit(1); |
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[17860] | 92 | } |
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[7779] | 93 | hp = gethostbyname(thishost.nodename); |
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| 94 | if (hp == NULL) { |
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| 95 | fprintf(stderr, "%s: Unable to get host name information: %s\n", |
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[11791] | 96 | argv[0], strerror(errno)); |
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[14069] | 97 | exit(1); |
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[7779] | 98 | } |
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[17860] | 99 | |
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| 100 | /* Clear the socket structure. */ |
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| 101 | memset(&sin, 0, sizeof(sin)); |
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| 102 | sin.sin_family = AF_INET; |
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| 103 | sin.sin_port = htons(LERT_PORT); |
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[8859] | 104 | memcpy(&sin.sin_addr.s_addr, hp->h_addr, hp->h_length); |
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[17860] | 105 | |
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| 106 | if (bind(s, (struct sockaddr *)&sin, sizeof(sin)) < 0) |
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| 107 | { |
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| 108 | fprintf(stderr, "%s: Unable to bind socket: %s\n", |
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| 109 | argv[0], strerror(errno)); |
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| 110 | exit(1); |
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| 111 | } |
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[7779] | 112 | |
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[17860] | 113 | fromlen = sizeof(from); |
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| 114 | |
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[14069] | 115 | for (;;) |
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| 116 | { |
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| 117 | plen = recvfrom(s, packet, sizeof(packet), 0, |
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| 118 | (struct sockaddr *)&from, &fromlen); |
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| 119 | if (plen < 0) |
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| 120 | { |
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| 121 | fprintf(stderr, "lertsrv: Error during recv: %s\n", |
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| 122 | strerror(errno)); |
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| 123 | sleep(1); /* Prevent infinite cpu hog loop */ |
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| 124 | continue; |
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| 125 | } |
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[7779] | 126 | |
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| 127 | #ifdef DEBUG |
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[14069] | 128 | fprintf(stderr, "lertsrv: Received packet of length %d\n", plen); |
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[7779] | 129 | #endif |
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| 130 | |
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[23655] | 131 | #ifdef HAVE_KRB4 |
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[17860] | 132 | if (packet[0] == '1') |
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[14069] | 133 | { |
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[17860] | 134 | /* krb4-authenticated version of the protocol. */ |
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| 135 | |
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| 136 | /* Copy authenticator into aligned region. */ |
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| 137 | memcpy(&authent, &packet[LERT_LENGTH], sizeof(authent)); |
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| 138 | |
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| 139 | strcpy(instance, "*"); |
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| 140 | status = krb_rd_req(&authent, LERT_SERVICE, instance, 0, &ad, |
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| 141 | LERTS_SRVTAB); |
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| 142 | |
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| 143 | if (status != KSUCCESS) |
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| 144 | { |
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| 145 | fprintf(stderr, "lertsrv: Kerberos failure: %s\n", |
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| 146 | krb_err_txt[status]); |
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| 147 | continue; |
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| 148 | } |
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| 149 | |
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| 150 | opacket[0] = '1'; |
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| 151 | if ((strlen(ad.pinst) != 0) || (strcmp(ad.prealm, "ATHENA.MIT.EDU"))) |
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| 152 | { |
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| 153 | fprintf(stderr, "lertsrv: %s.%s@%s -- Not null instance ATHENA " |
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| 154 | "realm.\n", ad.pname, ad.pinst, ad.prealm); |
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| 155 | opacket[1] = LERT_NOT_IN_DB; |
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| 156 | opacket[2] = '\0'; |
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| 157 | } |
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| 158 | else |
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[22403] | 159 | get_user(ad.pname, &(opacket[1]), ad.checksum, |
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| 160 | inet_ntoa(from.sin_addr)); |
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[17860] | 161 | |
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| 162 | /* Prepare krb_mk_priv message */ |
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| 163 | des_key_sched(ad.session, sched); |
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| 164 | |
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| 165 | /* Make the encrypted message: |
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| 166 | * version, code, data, plus terminating '\0' |
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| 167 | */ |
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| 168 | len = krb_mk_priv(opacket, ktxt.dat, |
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| 169 | LERT_CHECK + strlen(opacket + LERT_CHECK) + 1, |
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| 170 | sched, ad.session, &sin, &from); |
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| 171 | |
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| 172 | /* Send it. */ |
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| 173 | if (sendto(s, ktxt.dat, len, 0, |
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| 174 | (struct sockaddr *) &from, sizeof(from)) < 0) |
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| 175 | fprintf(stderr, "lertsrv: sendto failed: %s\n", strerror(errno)); |
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| 176 | |
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| 177 | /* Avoid confusion, zeroize now */ |
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| 178 | memset(&from, 0, sizeof(from)); |
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[14069] | 179 | } |
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[23655] | 180 | else |
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| 181 | #endif |
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| 182 | if (packet[0] == LERT_VERSION) |
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[17860] | 183 | { |
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| 184 | /* krb5-authenticated version of the protocol. */ |
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| 185 | if (!context) |
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| 186 | { |
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| 187 | problem = krb5_init_context(&context); |
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| 188 | if (problem) |
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| 189 | goto out; |
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| 190 | } |
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| 191 | problem = krb5_auth_con_init(context, &auth_con); |
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| 192 | if (problem) |
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| 193 | goto out; |
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[7779] | 194 | |
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[17860] | 195 | problem = |
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| 196 | krb5_auth_con_genaddrs(context, auth_con, s, |
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| 197 | KRB5_AUTH_CONTEXT_GENERATE_LOCAL_ADDR); |
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| 198 | if (problem) |
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| 199 | goto out; |
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[7779] | 200 | |
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[17860] | 201 | problem = krb5_sname_to_principal(context, NULL, LERT_SERVICE, |
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| 202 | KRB5_NT_SRV_HST, &server); |
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| 203 | if (problem) |
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| 204 | goto out; |
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[7779] | 205 | |
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[17860] | 206 | problem = krb5_kt_resolve(context, LERTS_KEYTAB, &keytab); |
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| 207 | if (problem) |
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| 208 | goto out; |
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[7779] | 209 | |
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[17860] | 210 | /* Get the authenticator. */ |
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| 211 | auth.data = packet + LERT_LENGTH; |
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| 212 | auth.length = sizeof(packet) - sizeof(int) - LERT_LENGTH; |
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[7779] | 213 | |
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[17860] | 214 | problem = krb5_rd_req(context, &auth_con, &auth, server, keytab, |
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| 215 | NULL, &ticket); |
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| 216 | if (problem) |
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| 217 | goto out; |
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[7779] | 218 | |
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[17860] | 219 | problem = krb5_copy_principal(context, ticket->enc_part2->client, |
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| 220 | &client); |
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| 221 | if (problem) |
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| 222 | goto out; |
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[7779] | 223 | |
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[17860] | 224 | opacket[0] = LERT_VERSION; |
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[7779] | 225 | |
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[17860] | 226 | /* If the client is something other than null instance principal |
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| 227 | * or is from a realm other than the server's local realm, punt |
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| 228 | * them. |
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| 229 | */ |
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[19980] | 230 | if ((krb5_princ_size(context, client) != 1) || |
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[17860] | 231 | krb5_realm_compare(context, client, server) == 0) |
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| 232 | { |
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| 233 | krb5_unparse_name(context, client, &username); |
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| 234 | if (username) |
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[23654] | 235 | fprintf(stderr, "lertsrv: %s not null instance in realm " |
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| 236 | "%s.\n", username, |
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| 237 | krb5_princ_realm(context, server)->data); |
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[17860] | 238 | opacket[1] = LERT_NOT_IN_DB; |
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| 239 | opacket[2] = '\0'; |
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| 240 | } |
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| 241 | else |
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| 242 | /* packet[1] will be a 0 or 1 depending on whether or not the |
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| 243 | * user called lert with the -n flag to indicate they don't |
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| 244 | * want to see the message anymore. |
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| 245 | * |
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| 246 | * The krb4 code passes in the checksum member of the AUTH_DAT |
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| 247 | * structure filled in by krb_rd_req(). While it will happen to |
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| 248 | * be 0 if the user didn't call lert with the -n flag, using |
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| 249 | * the value from the packet directly seems a bit more sane. |
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| 250 | */ |
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[19980] | 251 | { |
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| 252 | username = malloc(krb5_princ_component(context, client, 0)->length + 1); |
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| 253 | if (!username) |
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| 254 | goto out; |
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| 255 | strncpy(username, krb5_princ_component(context, client, 0)->data, |
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| 256 | krb5_princ_component(context, client, 0)->length); |
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| 257 | username[krb5_princ_component(context, client, 0)->length] = '\0'; |
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[17860] | 258 | |
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[22403] | 259 | get_user(username, &(opacket[1]), packet[1], |
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| 260 | inet_ntoa(from.sin_addr)); |
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[19980] | 261 | } |
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| 262 | |
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[17860] | 263 | inbuf.data = opacket; |
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| 264 | inbuf.length = strlen(opacket); |
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| 265 | |
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| 266 | problem = krb5_mk_priv(context, auth_con, &inbuf, &outbuf, NULL); |
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| 267 | if (problem) |
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| 268 | goto out; |
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| 269 | |
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| 270 | if (sendto(s, outbuf.data, outbuf.length, 0, |
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| 271 | (struct sockaddr *)&from, sizeof(from)) < 0) |
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| 272 | fprintf(stderr, "lertsrv: sendto failed: %s\n", strerror(errno)); |
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| 273 | |
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| 274 | /* Avoid confusion, zeroize now */ |
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| 275 | memset(&from, 0, sizeof(from)); |
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| 276 | |
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| 277 | out: |
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| 278 | if (problem) |
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| 279 | fprintf(stderr, "lertsrv: Kerberos error: %s\n", |
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| 280 | error_message(problem)); |
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| 281 | /* krb5 library checks if this is allocated for us. */ |
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| 282 | krb5_free_data_contents(context, &outbuf); |
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| 283 | memset(&outbuf, 0, sizeof(krb5_data)); |
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| 284 | if (client) |
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| 285 | krb5_free_principal(context, client); |
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| 286 | if (server) |
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| 287 | krb5_free_principal(context, server); |
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| 288 | if (ticket) |
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| 289 | krb5_free_ticket(context, ticket); |
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| 290 | if (auth_con) |
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| 291 | krb5_auth_con_free(context, auth_con); |
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[19980] | 292 | if (username) |
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| 293 | free(username); |
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[17860] | 294 | /* reset to NULL after freeing since we're going to go through |
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| 295 | * this loop again. |
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| 296 | */ |
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| 297 | client = server = NULL; |
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| 298 | ticket = NULL; |
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| 299 | auth_con = NULL; |
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[19980] | 300 | username = NULL; |
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[17860] | 301 | } |
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| 302 | else |
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| 303 | { |
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| 304 | fprintf(stderr, "lertsrv: Received packet with bad version: %d\n", |
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| 305 | packet[0]); |
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| 306 | } |
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[14069] | 307 | } |
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[7779] | 308 | |
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[14069] | 309 | return 0; |
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| 310 | } |
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[7779] | 311 | |
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[22403] | 312 | int get_user(char *pname, char *result, int onetime, char *ip) |
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[7779] | 313 | { |
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| 314 | DBM *db; |
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| 315 | DBM *db2; |
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| 316 | datum data; |
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| 317 | datum key; |
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| 318 | datum data2; |
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| 319 | char result2[128]; |
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| 320 | |
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[14069] | 321 | /* Prepare nil return. */ |
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[7779] | 322 | result[0] = LERT_FREE; |
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| 323 | result[1] = '\0'; |
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| 324 | |
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[14069] | 325 | /* Open the database. */ |
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[7779] | 326 | db = dbm_open(LERTS_DATA, O_RDWR, 0600); |
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[14069] | 327 | if (db == NULL) |
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| 328 | { |
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| 329 | fprintf(stderr, "Unable to open lert's database file %s: %s.\n", |
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| 330 | LERTS_DATA, strerror(errno)); |
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| 331 | return LERT_NO_DB; |
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| 332 | } |
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[7779] | 333 | |
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| 334 | key.dptr = pname; |
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| 335 | key.dsize = strlen(pname) + 1; |
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| 336 | |
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[14069] | 337 | /* Get the user. */ |
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[7779] | 338 | data = dbm_fetch(db, key); |
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[14069] | 339 | if (data.dptr == NULL) |
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| 340 | { |
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| 341 | /* Not in db. */ |
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| 342 | dbm_close(db); |
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[7779] | 343 | #ifdef LOGGING |
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[22403] | 344 | fprintf(stdout, "lertsrv: %s user %s not in db\n", ip, pname); |
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[7779] | 345 | #endif |
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[14069] | 346 | return LERT_NOT_IN_DB; |
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| 347 | } |
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| 348 | else |
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| 349 | { |
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| 350 | strncpy(&(result[1]), data.dptr, data.dsize); |
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| 351 | result[data.dsize + 1] = '\0'; |
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| 352 | |
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| 353 | if (onetime) |
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| 354 | { |
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| 355 | /* Add them to the log. */ |
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| 356 | db2 = dbm_open(LERTS_LOG, O_RDWR | O_CREAT, 0600); |
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| 357 | if (db2 == NULL) |
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| 358 | { |
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| 359 | fprintf(stderr, "Unable to open lert's log database %s: %s.\n", |
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| 360 | LERTS_LOG, strerror(errno)); |
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| 361 | } |
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| 362 | else |
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| 363 | { |
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| 364 | data2 = dbm_fetch(db2, key); |
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| 365 | if (data2.dptr == NULL) |
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| 366 | dbm_store(db2, key, data, DBM_INSERT); |
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| 367 | else |
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| 368 | { |
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| 369 | strncpy(result2, data2.dptr, data2.dsize); |
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| 370 | strncpy(&(result2[data2.dsize]), data.dptr, data.dsize); |
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| 371 | data2.dptr = result2; |
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| 372 | data2.dsize += data.dsize; |
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| 373 | dbm_store(db2, key, data2, DBM_REPLACE); |
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| 374 | } |
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| 375 | dbm_close(db2); |
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| 376 | } |
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| 377 | dbm_delete(db, key); |
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[7779] | 378 | } |
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[14069] | 379 | dbm_close(db); |
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[7779] | 380 | } |
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[14069] | 381 | |
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[7779] | 382 | result[0] = LERT_MSG; |
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| 383 | #ifdef LOGGING |
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[22403] | 384 | fprintf(stdout, "lertsrv: %s user %s in db with groups :%s:\n", ip, pname, |
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| 385 | result); |
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[7779] | 386 | #endif |
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[14069] | 387 | return LERT_GOTCHA; |
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[7779] | 388 | } |
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| 389 | |
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| 390 | |
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