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1 /* MasqMail Copyright (C) Oliver Kurth,
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2 *
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3 * This program is free software; you can redistribute it and/or modify
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4 * it under the terms of the GNU General Public License as published by
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5 * the Free Software Foundation; either version 2 of the License, or
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6 * (at your option) any later version.
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7 *
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8 * This program is distributed in the hope that it will be useful,
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9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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11 * GNU General Public License for more details.
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12 *
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13 * You should have received a copy of the GNU General Public License
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14 * along with this program; if not, write to the Free Software
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15 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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16 */
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17
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18 #include <sys/types.h>
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19 #include <netinet/in.h>
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20 #include <arpa/nameser.h>
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21 #include <resolv.h>
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22
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23 #include "masqmail.h"
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24
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25 #ifdef RESOLV_TEST
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26 #undef DEBUG
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27 #define DEBUG(x) if(x > 0)
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28 #define debugf g_print
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29 #endif
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30
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31 #ifdef ENABLE_RESOLVER
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32
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33 static union {
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34 HEADER hdr;
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35 unsigned char buf[PACKETSZ];
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36 } response;
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37 static unsigned char *resp_end;
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38 static unsigned char *resp_pos;
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39
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40 static int num_answers;
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41 static char name[MAX_DNSNAME];
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42
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43 unsigned short rr_type;
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44 unsigned short rr_dlen;
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45
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46 static unsigned short
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47 getshort(unsigned char *c)
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48 {
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49 unsigned short u;
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50 u = c[0];
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51 return (u << 8) + c[1];
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52 }
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53
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54 static int
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55 dns_resolve(char *domain, int type, gboolean do_search)
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56 {
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57 int n;
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58 int i;
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59
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60 int resp_len;
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61 /*errno = 0; */
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62
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63 /*
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64 if (!stralloc_copy(&glue,domain)) return DNS_MEM;
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65 if (!stralloc_0(&glue)) return DNS_MEM;
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66 */
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67
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68 // resp_len = res_query(domain, C_IN, type, response.buf, sizeof(response));
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69 DEBUG(5) debugf("DNS: before res_search()\n");
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70 if (do_search)
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71 resp_len = res_search(domain, C_IN, type, response.buf, sizeof(response));
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72 else
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73 resp_len = res_query(domain, C_IN, type, response.buf, sizeof(response));
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74 DEBUG(5) debugf("DBG: after res_search()\n");
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75
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76 if (resp_len <= 0) {
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77 /*
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78 if (errno == ECONNREFUSED) return DNS_SOFT;
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79 if (h_errno == TRY_AGAIN) return DNS_SOFT;
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80 return DNS_HARD;
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81 */
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82 return -1;
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83 }
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84 if (resp_len >= sizeof(response))
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85 resp_len = sizeof(response);
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86
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87 resp_end = response.buf + resp_len;
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88 resp_pos = response.buf + sizeof(HEADER);
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89 n = ntohs(response.hdr.qdcount);
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90
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91 while (n-- > 0) {
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92 i = dn_expand(response.buf, resp_end, resp_pos, name, MAX_DNSNAME);
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93 if (i < 0)
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94 return -1;
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95 DEBUG(5) debugf("DBG: resolve name = %s\n", name);
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96 resp_pos += i;
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97 i = resp_end - resp_pos;
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98 if (i < QFIXEDSZ)
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99 return -1;
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100 resp_pos += QFIXEDSZ;
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101 }
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102 num_answers = ntohs(response.hdr.ancount);
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103
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104 return 0;
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105 }
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106
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107 static int
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108 dns_next()
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109 {
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110 int i;
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111
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112 if (num_answers <= 0)
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113 return 2;
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114 num_answers--;
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115
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116 if (resp_pos == resp_end)
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117 return -1; /* soft */
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118
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119 i = dn_expand(response.buf, resp_end, resp_pos, name, 256);
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120 if (i < 0)
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121 return -1; /* soft */
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122 resp_pos += i;
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123
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124 i = resp_end - resp_pos;
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125 if (i < 4 + 3 * 2)
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126 return -1; /* soft */
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127
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128 rr_type = getshort(resp_pos);
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129 rr_dlen = getshort(resp_pos + 8);
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130 resp_pos += 10;
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131
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132 return 0;
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133 }
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134
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135 static int
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136 dns_getip(guint32 * ip)
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137 {
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138 int ret;
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139
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140 if ((ret = dns_next()))
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141 return ret;
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142
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143 if (rr_type == T_A) {
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144 if (rr_dlen < 4)
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145 return -1; /* soft */
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146 *ip = *(guint32 *) (resp_pos);
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147 DEBUG(5) debugf("DNS: dns_getip(): ip = %s\n", inet_ntoa(*(struct in_addr *) ip));
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148 resp_pos += rr_dlen;
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149
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150 return 1;
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151 }
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152 resp_pos += rr_dlen;
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153 return 0;
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154 }
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155
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156 static int
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157 dns_getmx(int *pref)
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158 {
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159 int ret;
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160
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161 if ((ret = dns_next()))
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162 return ret;
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163
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164 if (rr_type == T_MX) {
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165 if (rr_dlen < 3)
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166 return -1; /* soft */
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167
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168 *pref = (resp_pos[0] << 8) + resp_pos[1];
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169 if (dn_expand(response.buf, resp_end, resp_pos + 2, name, MAX_DNSNAME) < 0)
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170 return -1;
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171
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172 resp_pos += rr_dlen;
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173
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174 return 1;
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175 }
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176 resp_pos += rr_dlen;
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177 return 0;
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178 }
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179
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180 /*
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181 static int
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182 dns_getname(int type)
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183 {
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184 int ret;
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185
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186 if((ret = dns_next())) return ret;
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187
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188 if (rr_type == type){
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189 if (dn_expand(response.buf, resp_end, resp_pos, name, MAX_DNSNAME) < 0)
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190 return -1;
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191
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192 resp_pos += rr_dlen;
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193
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194 return 1;
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195 }
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196 resp_pos += rr_dlen;
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197 return 0;
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198 }
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199 */
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200
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201 static int
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202 dns_look_ip(gchar * domain, guint32 * ip)
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203 {
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204 gchar *n = domain;
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205
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206 while (TRUE) {
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207 if (dns_resolve(n, T_A, FALSE) == 0) {
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208 dns_next();
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209 if (rr_type == T_A) {
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210 if (rr_dlen < 4)
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211 return -1; /* soft */
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212 *ip = *(guint32 *) (resp_pos);
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213
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214 DEBUG(5) debugf("DNS: dns_look_ip(): ip = %s\n", inet_ntoa(*(struct in_addr *) ip));
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215
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216 resp_pos += rr_dlen;
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217 return 0;
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218 } else if (rr_type == T_CNAME) {
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219 if (dn_expand(response.buf, resp_end, resp_pos, name, MAX_DNSNAME) < 0)
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220 return -1;
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221
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222 DEBUG(5) debugf("DNS: (CNAME) dns_look_ip(): name = %s\n", name);
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223
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224 resp_pos += rr_dlen;
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225 n = name;
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226 } else
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227 return -1;
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228 } else
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229 return -1;
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230 }
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231 }
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232
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233 GList*
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234 resolve_dns_a(GList * list, gchar * domain)
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235 {
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236 int ret;
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237
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238 DEBUG(5) debugf("DNS: resolve_dns_a entered\n");
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239
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240 if (dns_resolve(domain, T_A, TRUE) == 0) {
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241 mxip_addr mxip;
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242 while ((ret = dns_getip(&(mxip.ip))) != 2) {
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243 if (ret == 1) {
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244 mxip.name = g_strdup(name);
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245 mxip.pref = 0;
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246 list = g_list_append(list, g_memdup(&mxip, sizeof(mxip)));
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247 }
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248 }
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249 }
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250 return list;
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251 }
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252
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253 static gint
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254 _mx_sort_func(gconstpointer aa, gconstpointer bb)
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255 {
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256 const mxip_addr *a = (mxip_addr *) aa;
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257 const mxip_addr *b = (mxip_addr *) bb;
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258
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259 if (a->pref == b->pref)
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260 return a->ip - b->ip;
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261 else
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262 return a->pref - b->pref;
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263 }
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264
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265 GList*
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266 resolve_dns_mx(GList * list, gchar * domain)
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267 {
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268 GList *node;
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269 int ret;
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270 int cnt = 0;
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271
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272 DEBUG(5) debugf("DNS: resolve_dns_mx entered\n");
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273
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274 if (dns_resolve(domain, T_MX, TRUE) == 0) {
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275 GList *node_next;
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276 mxip_addr mxip;
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277 while ((ret = dns_getmx(&(mxip.pref))) != 2) {
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278 if (ret == 1) {
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279 mxip.name = g_strdup(name);
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280 mxip.ip = rand();
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281 list = g_list_append(list, g_memdup(&mxip, sizeof(mxip)));
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282 cnt++;
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283 }
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284 }
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285
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286 DEBUG(5) debugf("DNS: found %d mx records\n", cnt);
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287
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288 /* to randomize sequences with equal pref values,
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289 we temporarily 'misused' the ip field and
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290 put a random number in it as a secondary sort key.
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291 */
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292 list = g_list_sort(list, _mx_sort_func);
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293
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294 /* CNAME resolving has to be added as well. */
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295
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296 for (node = g_list_first(list); node != NULL; node = node_next) {
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297
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298 mxip_addr *p_mxip = (mxip_addr *) (node->data);
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299 node_next = g_list_next(node);
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300
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301 if (dns_look_ip(p_mxip->name, &(p_mxip->ip)) != 0) {
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302 DEBUG(1) debugf("DNS: could not resolve target of mx %s\n", p_mxip->name);
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303 list = g_list_remove_link(list, node);
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304 g_free(node->data);
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305 g_list_free_1(node);
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306 }
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307 }
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308 }
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309 return list;
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310 }
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311
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312 #endif
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313
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314 /* now something completely different... */
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315
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316 GList*
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317 resolve_byname(GList * list, gchar * domain)
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318 {
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319 struct hostent *hent;
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320
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321 DEBUG(5) debugf("DNS: resolve_byname entered\n");
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322
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323 if ((hent = gethostbyname(domain))) {
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324 char *haddr;
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325 int i = 0;
|
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326 while ((haddr = hent->h_addr_list[i++])) {
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327 mxip_addr mxip;
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328 mxip.ip = *(guint32 *) (haddr);
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329 mxip.pref = 0;
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330 mxip.name = g_strdup(hent->h_name);
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331 list = g_list_append(list, g_memdup(&mxip, sizeof(mxip)));
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332 }
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333 }
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334 return list;
|
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335 }
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336
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337 #ifdef RESOLV_TEST
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338 int
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339 main(int argc, char *argv[])
|
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340 {
|
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341 GList *addr_list = NULL, *node;
|
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342
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343 g_print("starting res_init()\n");
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344 g_print("retrans = %d, retry = %d\n", _res.retrans, _res.retry);
|
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345 if (res_init() == 0) {
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346 addr_list = resolve_dns_a(NULL, argv[1]);
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347 g_print("A:\n");
|
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|
348 foreach(addr_list, node) {
|
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|
349 mxip_addr *p_mxip = (mxip_addr *) (node->data);
|
meillo@10
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350 printf("name = %s\n IP = %s\n", p_mxip->name, inet_ntoa(*(struct in_addr *) &(p_mxip->ip)));
|
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|
351 }
|
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|
352 addr_list = resolve_dns_mx(NULL, argv[1]);
|
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|
353 g_print("MX:\n");
|
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|
354 foreach(addr_list, node) {
|
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|
355 mxip_addr *p_mxip = (mxip_addr *) (node->data);
|
meillo@15
|
356 printf("name = %s\n IP = %s pref = %d\n", p_mxip->name,
|
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|
357 inet_ntoa(*(struct in_addr *) &(p_mxip->ip)), p_mxip->pref);
|
meillo@10
|
358 }
|
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|
359 {
|
meillo@10
|
360 guint32 ip;
|
meillo@10
|
361 dns_look_ip(argv[1], &ip);
|
meillo@10
|
362 printf("dns_look_ip: %s\n", inet_ntoa(*((struct in_addr *) (&ip))));
|
meillo@10
|
363 }
|
meillo@10
|
364 } else
|
meillo@10
|
365 printf("res_init() failed.\n");
|
meillo@0
|
366 }
|
meillo@0
|
367 #endif
|