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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 16:16:13 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 16:16:13 +0000 |
commit | e90fcc54809db2591dc083f43ef54c6ec8c60847 (patch) | |
tree | f20bc206c3c2d5d59d37c46c5cf5d53a20642556 /src/spf.c | |
parent | Initial commit. (diff) | |
download | exim4-e90fcc54809db2591dc083f43ef54c6ec8c60847.tar.xz exim4-e90fcc54809db2591dc083f43ef54c6ec8c60847.zip |
Adding upstream version 4.96.upstream/4.96upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | src/spf.c | 420 |
1 files changed, 420 insertions, 0 deletions
diff --git a/src/spf.c b/src/spf.c new file mode 100644 index 0000000..db6eea3 --- /dev/null +++ b/src/spf.c @@ -0,0 +1,420 @@ +/************************************************* +* Exim - an Internet mail transport agent * +*************************************************/ + +/* SPF support. + Copyright (c) The Exim Maintainers 2015 - 2022 + Copyright (c) Tom Kistner <tom@duncanthrax.net> 2004 - 2014 + License: GPL +*/ + +/* Code for calling spf checks via libspf-alt. Called from acl.c. */ + +#include "exim.h" +#ifdef SUPPORT_SPF + +/* must be kept in numeric order */ +static spf_result_id spf_result_id_list[] = { + /* name value */ + { US"invalid", 0}, + { US"neutral", 1 }, + { US"pass", 2 }, + { US"fail", 3 }, + { US"softfail", 4 }, + { US"none", 5 }, + { US"temperror", 6 }, /* RFC 4408 defined */ + { US"permerror", 7 } /* RFC 4408 defined */ +}; + +SPF_server_t *spf_server = NULL; +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; + + +gstring * +spf_lib_version_report(gstring * g) +{ +int maj, min, patch; + +SPF_get_lib_version(&maj, &min, &patch); +g = string_fmt_append(g, "Library version: spf2: Compile: %d.%d.%d\n", + SPF_LIB_VERSION_MAJOR, SPF_LIB_VERSION_MINOR, SPF_LIB_VERSION_PATCH); +g = string_fmt_append(g, " Runtime: %d.%d.%d\n", + maj, min, patch); +return g; +} + + + +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(void) +{ +SPF_dns_server_t * dc; +int debug = 0; +const uschar *s; + +DEBUG(D_receive) debug = 1; + +/* 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)) + { + DEBUG(D_receive) debug_printf("spf: SPF_server_set_rec_dom(\"%s\") failed.\n", + primary_hostname); + spf_server = NULL; + return FALSE; + } + +spf_request = SPF_request_new(spf_server); + +if ( SPF_request_set_ipv4_str(spf_request, CS spf_remote_addr) + && SPF_request_set_ipv6_str(spf_request, CS spf_remote_addr) + ) + { + DEBUG(D_receive) + debug_printf("spf: SPF_request_set_ipv4_str() and " + "SPF_request_set_ipv6_str() failed [%s]\n", spf_remote_addr); + spf_server = NULL; + spf_request = NULL; + return FALSE; + } + +if (SPF_request_set_helo_dom(spf_request, CS spf_helo_domain)) + { + DEBUG(D_receive) debug_printf("spf: SPF_set_helo_dom(\"%s\") failed.\n", + spf_helo_domain); + spf_server = NULL; + spf_request = NULL; + return FALSE; + } + +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. + +Return: OK/FAIL */ + +int +spf_process(const uschar **listptr, uschar *spf_envelope_sender, int action) +{ +int sep = 0; +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 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); + + /* set up expansion items */ + spf_header_comment = US SPF_response_get_header_comment(spf_response); + spf_received = US SPF_response_get_received_spf(spf_response); + spf_result = US SPF_strresult(SPF_response_result(spf_response)); + 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 */ +DEBUG(D_acl) debug_printf("SPF result is %s (%d)\n", SPF_strresult(rc), rc); + +if (action == SPF_PROCESS_GUESS && (!strcmp (SPF_strresult(rc), "none"))) + return spf_process(listptr, spf_envelope_sender, SPF_PROCESS_FALLBACK); + +while ((spf_result_id = string_nextinlist(&list, &sep, NULL, 0))) + { + BOOL negate, result; + + if ((negate = spf_result_id[0] == '!')) + spf_result_id++; + + result = Ustrcmp(spf_result_id, spf_result_id_list[rc].name) == 0; + if (negate != result) return OK; + } + +/* no match */ +return FAIL; +} + + + +gstring * +authres_spf(gstring * g) +{ +uschar * s; +if (!spf_result) return g; + +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=<>"); +} + + +#endif |