X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/e34f8ca2022e340d3c0e36260a0232fab306dfcc..28d2eab1414ef8d20ff0fde7026aa52fd01ef795:/src/src/spf.c diff --git a/src/src/spf.c b/src/src/spf.c index 12994a690..2f55fb77c 100644 --- a/src/src/spf.c +++ b/src/src/spf.c @@ -2,10 +2,10 @@ * Exim - an Internet mail transport agent * *************************************************/ -/* Experimental SPF support. +/* SPF support. Copyright (c) Tom Kistner 2004 - 2014 License: GPL - Copyright (c) The Exim Maintainers 2015 - 2018 + Copyright (c) The Exim Maintainers 2015 - 2020 */ /* Code for calling spf checks via libspf-alt. Called from acl.c. */ @@ -22,8 +22,6 @@ static spf_result_id spf_result_id_list[] = { { US"fail", 3 }, { US"softfail", 4 }, { US"none", 5 }, - { US"err_temp", 6 }, /* Deprecated Apr 2014 */ - { US"err_perm", 7 }, /* Deprecated Apr 2014 */ { US"temperror", 6 }, /* RFC 4408 defined */ { US"permerror", 7 } /* RFC 4408 defined */ }; @@ -33,23 +31,248 @@ SPF_request_t *spf_request = NULL; SPF_response_t *spf_response = NULL; SPF_response_t *spf_response_2mx = NULL; +SPF_dns_rr_t * spf_nxdomain = NULL; -/* spf_init sets up a context that can be re-used for several - messages on the same SMTP connection (that come from the - same host with the same HELO string) -Return: Boolean success */ +void +spf_lib_version_report(FILE * fp) +{ +int maj, min, patch; +SPF_get_lib_version(&maj, &min, &patch); +fprintf(fp, "Library version: spf2: Compile: %d.%d.%d\n", + SPF_LIB_VERSION_MAJOR, SPF_LIB_VERSION_MINOR, SPF_LIB_VERSION_PATCH); +fprintf(fp, " Runtime: %d.%d.%d\n", + maj, min, patch); +} + + + +static SPF_dns_rr_t * +SPF_dns_exim_lookup(SPF_dns_server_t *spf_dns_server, + const char *domain, ns_type rr_type, int should_cache) +{ +dns_answer * dnsa = store_get_dns_answer(); +dns_scan dnss; +SPF_dns_rr_t * spfrr; +unsigned found = 0; + +SPF_dns_rr_t srr = { + .domain = CS domain, /* query information */ + .domain_buf_len = 0, + .rr_type = rr_type, + + .rr_buf_len = 0, /* answer information */ + .rr_buf_num = 0, /* no free of s */ + .utc_ttl = 0, + + .hook = NULL, /* misc information */ + .source = spf_dns_server +}; +int dns_rc; + +DEBUG(D_receive) debug_printf("SPF_dns_exim_lookup '%s'\n", domain); + +/* Shortcircuit SPF RR lookups by returning NO_DATA. They were obsoleted by +RFC 6686/7208 years ago. see bug #1294 */ + +if (rr_type == T_SPF) + { + HDEBUG(D_host_lookup) debug_printf("faking NO_DATA for SPF RR(99) lookup\n"); + srr.herrno = NO_DATA; + SPF_dns_rr_dup(&spfrr, &srr); + store_free_dns_answer(dnsa); + return spfrr; + } + +switch (dns_rc = dns_lookup(dnsa, US domain, rr_type, NULL)) + { + case DNS_SUCCEED: srr.herrno = NETDB_SUCCESS; break; + case DNS_AGAIN: srr.herrno = TRY_AGAIN; break; + case DNS_NOMATCH: srr.herrno = HOST_NOT_FOUND; break; + case DNS_NODATA: srr.herrno = NO_DATA; break; + case DNS_FAIL: + default: srr.herrno = NO_RECOVERY; break; + } + +for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr; + rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)) + if (rr->type == rr_type) found++; + +if (found == 0) + { + SPF_dns_rr_dup(&spfrr, &srr); + store_free_dns_answer(dnsa); + return spfrr; + } + +srr.rr = store_malloc(sizeof(SPF_dns_rr_data_t) * found); + +found = 0; +for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr; + rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)) + if (rr->type == rr_type) + { + const uschar * s = rr->data; + + srr.ttl = rr->ttl; + switch(rr_type) + { + case T_MX: + s += 2; /* skip the MX precedence field */ + case T_PTR: + { + uschar * buf = store_malloc(256); + (void)dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen, s, + (DN_EXPAND_ARG4_TYPE)buf, 256); + s = buf; + break; + } + + case T_TXT: + { + gstring * g = NULL; + uschar chunk_len; + + if (strncmpic(rr->data+1, US SPF_VER_STR, 6) != 0) + { + HDEBUG(D_host_lookup) debug_printf("not an spf record: %.*s\n", + (int) s[0], s+1); + continue; + } + + for (int off = 0; off < rr->size; off += chunk_len) + { + if (!(chunk_len = s[off++])) break; + g = string_catn(g, s+off, chunk_len); + } + if (!g) + continue; + gstring_release_unused(g); + s = string_copy_malloc(string_from_gstring(g)); + DEBUG(D_receive) debug_printf("SPF_dns_exim_lookup '%s'\n", s); + break; + } + + case T_A: + case T_AAAA: + default: + { + uschar * buf = store_malloc(dnsa->answerlen + 1); + s = memcpy(buf, s, dnsa->answerlen + 1); + break; + } + } + srr.rr[found++] = (void *) s; + } + +/* Did we filter out all TXT RRs? Return NO_DATA instead of SUCCESS with +empty ANSWER section. */ + +if (!(srr.num_rr = found)) + srr.herrno = NO_DATA; + +/* spfrr->rr must have been malloc()d for this */ +SPF_dns_rr_dup(&spfrr, &srr); +store_free_dns_answer(dnsa); +return spfrr; +} + + + +SPF_dns_server_t * +SPF_dns_exim_new(int debug) +{ +SPF_dns_server_t * spf_dns_server = store_malloc(sizeof(SPF_dns_server_t)); + +DEBUG(D_receive) debug_printf("SPF_dns_exim_new\n"); + +memset(spf_dns_server, 0, sizeof(SPF_dns_server_t)); +spf_dns_server->destroy = NULL; +spf_dns_server->lookup = SPF_dns_exim_lookup; +spf_dns_server->get_spf = NULL; +spf_dns_server->get_exp = NULL; +spf_dns_server->add_cache = NULL; +spf_dns_server->layer_below = NULL; +spf_dns_server->name = "exim"; +spf_dns_server->debug = debug; + +/* XXX This might have to return NO_DATA sometimes. */ + +spf_nxdomain = SPF_dns_rr_new_init(spf_dns_server, + "", ns_t_any, 24 * 60 * 60, HOST_NOT_FOUND); +if (!spf_nxdomain) + { + free(spf_dns_server); + return NULL; + } + +return spf_dns_server; +} + + + + +/* Construct the SPF library stack. + Return: Boolean success. +*/ BOOL -spf_init(uschar *spf_helo_domain, uschar *spf_remote_addr) +spf_init(void) { -spf_server = SPF_server_new(SPF_DNS_CACHE, 0); +SPF_dns_server_t * dc; +int debug = 0; +const uschar *s; + +DEBUG(D_receive) debug = 1; -if (!spf_server) +/* We insert our own DNS access layer rather than letting the spf library +do it, so that our dns access path is used for debug tracing and for the +testsuite. */ + +if (!(dc = SPF_dns_exim_new(debug))) + { + DEBUG(D_receive) debug_printf("spf: SPF_dns_exim_new() failed\n"); + return FALSE; + } +if (!(dc = SPF_dns_cache_new(dc, NULL, debug, 8))) + { + DEBUG(D_receive) debug_printf("spf: SPF_dns_cache_new() failed\n"); + return FALSE; + } +if (!(spf_server = SPF_server_new_dns(dc, debug))) { DEBUG(D_receive) debug_printf("spf: SPF_server_new() failed.\n"); return FALSE; } + /* Override the outdated explanation URL. + See https://www.mail-archive.com/mailop@mailop.org/msg08019.html + Used to work as "Please%_see%_http://www.open-spf.org/Why?id=%{S}&ip=%{C}&receiver=%{R}", + but is broken now (May 18th, 2020) */ +if (!(s = expand_string(spf_smtp_comment_template))) + log_write(0, LOG_MAIN|LOG_PANIC_DIE, "expansion of spf_smtp_comment_template failed"); + +SPF_server_set_explanation(spf_server, CCS s, &spf_response); +if (SPF_response_errcode(spf_response) != SPF_E_SUCCESS) + log_write(0, LOG_MAIN|LOG_PANIC_DIE, "%s", SPF_strerror(SPF_response_errcode(spf_response))); + +return TRUE; +} + + +/* Set up a context that can be re-used for several + messages on the same SMTP connection (that come from the + same host with the same HELO string). + +Return: Boolean success +*/ + +BOOL +spf_conn_init(uschar * spf_helo_domain, uschar * spf_remote_addr) +{ +DEBUG(D_receive) + debug_printf("spf_conn_init: %s %s\n", spf_helo_domain, spf_remote_addr); + +if (!spf_server && !spf_init()) return FALSE; if (SPF_server_set_rec_dom(spf_server, CS primary_hostname)) { @@ -86,6 +309,22 @@ return TRUE; } +void +spf_response_debug(SPF_response_t * spf_response) +{ +if (SPF_response_messages(spf_response) == 0) + debug_printf(" (no errors)\n"); +else for (int i = 0; i < SPF_response_messages(spf_response); i++) + { + SPF_error_t * err = SPF_response_message(spf_response, i); + debug_printf( "%s_msg = (%d) %s\n", + (SPF_error_errorp(err) ? "warn" : "err"), + SPF_error_code(err), + SPF_error_message(err)); + } +} + + /* spf_process adds the envelope sender address to the existing context (if any), retrieves the result, sets up expansion strings and evaluates the condition outcome. @@ -100,19 +339,24 @@ const uschar *list = *listptr; uschar *spf_result_id; int rc = SPF_RESULT_PERMERROR; +DEBUG(D_receive) debug_printf("spf_process\n"); + if (!(spf_server && spf_request)) /* no global context, assume temp error and skip to evaluation */ rc = SPF_RESULT_PERMERROR; else if (SPF_request_set_env_from(spf_request, CS spf_envelope_sender)) - /* Invalid sender address. This should be a real rare occurence */ + /* Invalid sender address. This should be a real rare occurrence */ rc = SPF_RESULT_PERMERROR; else { /* get SPF result */ if (action == SPF_PROCESS_FALLBACK) + { SPF_request_query_fallback(spf_request, &spf_response, CS spf_guess); + spf_result_guessed = TRUE; + } else SPF_request_query_mailfrom(spf_request, &spf_response); @@ -123,6 +367,8 @@ else spf_smtp_comment = US SPF_response_get_smtp_comment(spf_response); rc = SPF_response_result(spf_response); + + DEBUG(D_acl) spf_response_debug(spf_response); } /* We got a result. Now see if we should return OK or FAIL for it */ @@ -151,10 +397,21 @@ return FAIL; gstring * authres_spf(gstring * g) { +uschar * s; if (!spf_result) return g; -return string_append(g, 4, US";\n\tspf=", spf_result, - US" smtp.mailfrom=", expand_string(US"$sender_address_domain")); +g = string_append(g, 2, US";\n\tspf=", spf_result); +if (spf_result_guessed) + g = string_cat(g, US" (best guess record for domain)"); + +s = expand_string(US"$sender_address_domain"); +if (s && *s) + return string_append(g, 2, US" smtp.mailfrom=", s); + +s = sender_helo_name; +return s && *s + ? string_append(g, 2, US" smtp.helo=", s) + : string_cat(g, US" smtp.mailfrom=<>"); }