| 1 | /************************************************* |
| 2 | * Exim - an Internet mail transport agent * |
| 3 | *************************************************/ |
| 4 | |
| 5 | /* Experimental SPF support. |
| 6 | Copyright (c) Tom Kistner <tom@duncanthrax.net> 2004 - 2014 |
| 7 | License: GPL |
| 8 | Copyright (c) The Exim Maintainers 2015 - 2018 |
| 9 | */ |
| 10 | |
| 11 | /* Code for calling spf checks via libspf-alt. Called from acl.c. */ |
| 12 | |
| 13 | #include "exim.h" |
| 14 | #ifdef SUPPORT_SPF |
| 15 | |
| 16 | /* must be kept in numeric order */ |
| 17 | static spf_result_id spf_result_id_list[] = { |
| 18 | /* name value */ |
| 19 | { US"invalid", 0}, |
| 20 | { US"neutral", 1 }, |
| 21 | { US"pass", 2 }, |
| 22 | { US"fail", 3 }, |
| 23 | { US"softfail", 4 }, |
| 24 | { US"none", 5 }, |
| 25 | { US"temperror", 6 }, /* RFC 4408 defined */ |
| 26 | { US"permerror", 7 } /* RFC 4408 defined */ |
| 27 | }; |
| 28 | |
| 29 | SPF_server_t *spf_server = NULL; |
| 30 | SPF_request_t *spf_request = NULL; |
| 31 | SPF_response_t *spf_response = NULL; |
| 32 | SPF_response_t *spf_response_2mx = NULL; |
| 33 | |
| 34 | |
| 35 | /* spf_init sets up a context that can be re-used for several |
| 36 | messages on the same SMTP connection (that come from the |
| 37 | same host with the same HELO string) |
| 38 | |
| 39 | Return: Boolean success */ |
| 40 | |
| 41 | BOOL |
| 42 | spf_init(uschar *spf_helo_domain, uschar *spf_remote_addr) |
| 43 | { |
| 44 | spf_server = SPF_server_new(SPF_DNS_CACHE, 0); |
| 45 | |
| 46 | if (!spf_server) |
| 47 | { |
| 48 | DEBUG(D_receive) debug_printf("spf: SPF_server_new() failed.\n"); |
| 49 | return FALSE; |
| 50 | } |
| 51 | |
| 52 | if (SPF_server_set_rec_dom(spf_server, CS primary_hostname)) |
| 53 | { |
| 54 | DEBUG(D_receive) debug_printf("spf: SPF_server_set_rec_dom(\"%s\") failed.\n", |
| 55 | primary_hostname); |
| 56 | spf_server = NULL; |
| 57 | return FALSE; |
| 58 | } |
| 59 | |
| 60 | spf_request = SPF_request_new(spf_server); |
| 61 | |
| 62 | if ( SPF_request_set_ipv4_str(spf_request, CS spf_remote_addr) |
| 63 | && SPF_request_set_ipv6_str(spf_request, CS spf_remote_addr) |
| 64 | ) |
| 65 | { |
| 66 | DEBUG(D_receive) |
| 67 | debug_printf("spf: SPF_request_set_ipv4_str() and " |
| 68 | "SPF_request_set_ipv6_str() failed [%s]\n", spf_remote_addr); |
| 69 | spf_server = NULL; |
| 70 | spf_request = NULL; |
| 71 | return FALSE; |
| 72 | } |
| 73 | |
| 74 | if (SPF_request_set_helo_dom(spf_request, CS spf_helo_domain)) |
| 75 | { |
| 76 | DEBUG(D_receive) debug_printf("spf: SPF_set_helo_dom(\"%s\") failed.\n", |
| 77 | spf_helo_domain); |
| 78 | spf_server = NULL; |
| 79 | spf_request = NULL; |
| 80 | return FALSE; |
| 81 | } |
| 82 | |
| 83 | return TRUE; |
| 84 | } |
| 85 | |
| 86 | |
| 87 | /* spf_process adds the envelope sender address to the existing |
| 88 | context (if any), retrieves the result, sets up expansion |
| 89 | strings and evaluates the condition outcome. |
| 90 | |
| 91 | Return: OK/FAIL */ |
| 92 | |
| 93 | int |
| 94 | spf_process(const uschar **listptr, uschar *spf_envelope_sender, int action) |
| 95 | { |
| 96 | int sep = 0; |
| 97 | const uschar *list = *listptr; |
| 98 | uschar *spf_result_id; |
| 99 | int rc = SPF_RESULT_PERMERROR; |
| 100 | |
| 101 | if (!(spf_server && spf_request)) |
| 102 | /* no global context, assume temp error and skip to evaluation */ |
| 103 | rc = SPF_RESULT_PERMERROR; |
| 104 | |
| 105 | else if (SPF_request_set_env_from(spf_request, CS spf_envelope_sender)) |
| 106 | /* Invalid sender address. This should be a real rare occurrence */ |
| 107 | rc = SPF_RESULT_PERMERROR; |
| 108 | |
| 109 | else |
| 110 | { |
| 111 | /* get SPF result */ |
| 112 | if (action == SPF_PROCESS_FALLBACK) |
| 113 | { |
| 114 | SPF_request_query_fallback(spf_request, &spf_response, CS spf_guess); |
| 115 | spf_result_guessed = TRUE; |
| 116 | } |
| 117 | else |
| 118 | SPF_request_query_mailfrom(spf_request, &spf_response); |
| 119 | |
| 120 | /* set up expansion items */ |
| 121 | spf_header_comment = US SPF_response_get_header_comment(spf_response); |
| 122 | spf_received = US SPF_response_get_received_spf(spf_response); |
| 123 | spf_result = US SPF_strresult(SPF_response_result(spf_response)); |
| 124 | spf_smtp_comment = US SPF_response_get_smtp_comment(spf_response); |
| 125 | |
| 126 | rc = SPF_response_result(spf_response); |
| 127 | } |
| 128 | |
| 129 | /* We got a result. Now see if we should return OK or FAIL for it */ |
| 130 | DEBUG(D_acl) debug_printf("SPF result is %s (%d)\n", SPF_strresult(rc), rc); |
| 131 | |
| 132 | if (action == SPF_PROCESS_GUESS && (!strcmp (SPF_strresult(rc), "none"))) |
| 133 | return spf_process(listptr, spf_envelope_sender, SPF_PROCESS_FALLBACK); |
| 134 | |
| 135 | while ((spf_result_id = string_nextinlist(&list, &sep, NULL, 0))) |
| 136 | { |
| 137 | BOOL negate, result; |
| 138 | |
| 139 | if ((negate = spf_result_id[0] == '!')) |
| 140 | spf_result_id++; |
| 141 | |
| 142 | result = Ustrcmp(spf_result_id, spf_result_id_list[rc].name) == 0; |
| 143 | if (negate != result) return OK; |
| 144 | } |
| 145 | |
| 146 | /* no match */ |
| 147 | return FAIL; |
| 148 | } |
| 149 | |
| 150 | |
| 151 | |
| 152 | gstring * |
| 153 | authres_spf(gstring * g) |
| 154 | { |
| 155 | uschar * s; |
| 156 | if (!spf_result) return g; |
| 157 | |
| 158 | g = string_append(g, 2, US";\n\tspf=", spf_result); |
| 159 | if (spf_result_guessed) |
| 160 | g = string_cat(g, US" (best guess record for domain)"); |
| 161 | |
| 162 | s = expand_string(US"$sender_address_domain"); |
| 163 | return s && *s |
| 164 | ? string_append(g, 2, US" smtp.mailfrom=", s) |
| 165 | : string_cat(g, US" smtp.mailfrom=<>"); |
| 166 | } |
| 167 | |
| 168 | |
| 169 | #endif |