diff options
Diffstat (limited to 'src/regex.c')
| -rw-r--r-- | src/regex.c | 217 |
1 files changed, 217 insertions, 0 deletions
diff --git a/src/regex.c b/src/regex.c new file mode 100644 index 0000000..5c0f7c4 --- /dev/null +++ b/src/regex.c @@ -0,0 +1,217 @@ +/************************************************* +* Exim - an Internet mail transport agent * +*************************************************/ + +/* + * Copyright (c) The Exim Maintainers 2016 - 2022 + * Copyright (c) Tom Kistner <tom@duncanthrax.net> 2003-2015 + * License: GPL + */ + +/* Code for matching regular expressions against headers and body. + Called from acl.c. */ + +#include "exim.h" +#ifdef WITH_CONTENT_SCAN +#include <unistd.h> +#include <sys/mman.h> + +/* Structure to hold a list of Regular expressions */ +typedef struct pcre_list { + pcre2_code *re; + uschar *pcre_text; + struct pcre_list *next; +} pcre_list; + +uschar regex_match_string_buffer[1024]; + +extern FILE *mime_stream; +extern uschar *mime_current_boundary; + +static pcre_list * +compile(const uschar * list) +{ +int sep = 0; +uschar *regex_string; +pcre_list *re_list_head = NULL; +pcre_list *ri; + +/* precompile our regexes */ +while ((regex_string = string_nextinlist(&list, &sep, NULL, 0))) + if (strcmpic(regex_string, US"false") != 0 && Ustrcmp(regex_string, "0") != 0) + { + pcre2_code * re; + int err; + PCRE2_SIZE pcre_erroffset; + + /* compile our regular expression */ + if (!(re = pcre2_compile( (PCRE2_SPTR) regex_string, PCRE2_ZERO_TERMINATED, + 0, &err, &pcre_erroffset, pcre_cmp_ctx))) + { + uschar errbuf[128]; + pcre2_get_error_message(err, errbuf, sizeof(errbuf)); + log_write(0, LOG_MAIN, + "regex acl condition warning - error in regex '%s': %s at offset %ld, skipped.", + regex_string, errbuf, (long)pcre_erroffset); + continue; + } + + ri = store_get(sizeof(pcre_list), GET_UNTAINTED); + ri->re = re; + ri->pcre_text = regex_string; + ri->next = re_list_head; + re_list_head = ri; + } +return re_list_head; +} + +static int +matcher(pcre_list * re_list_head, uschar * linebuffer, int len) +{ +pcre2_match_data * md = pcre2_match_data_create(REGEX_VARS + 1, pcre_gen_ctx); + +for (pcre_list * ri = re_list_head; ri; ri = ri->next) + { + int n; + + /* try matcher on the line */ + if ((n = pcre2_match(ri->re, (PCRE2_SPTR)linebuffer, len, 0, 0, md, pcre_mtc_ctx)) > 0) + { + Ustrncpy(regex_match_string_buffer, ri->pcre_text, + sizeof(regex_match_string_buffer)-1); + regex_match_string = regex_match_string_buffer; + + for (int nn = 1; nn < n; nn++) + { + PCRE2_UCHAR * cstr; + PCRE2_SIZE cslen; + pcre2_substring_get_bynumber(md, nn, &cstr, &cslen); + regex_vars[nn-1] = CUS cstr; + } + + return OK; + } + } +pcre2_match_data_free(md); +return FAIL; +} + +int +regex(const uschar **listptr) +{ +unsigned long mbox_size; +FILE *mbox_file; +pcre_list *re_list_head; +uschar *linebuffer; +long f_pos = 0; +int ret = FAIL; + +/* reset expansion variable */ +regex_match_string = NULL; + +if (!mime_stream) /* We are in the DATA ACL */ + { + if (!(mbox_file = spool_mbox(&mbox_size, NULL, NULL))) + { /* error while spooling */ + log_write(0, LOG_MAIN|LOG_PANIC, + "regex acl condition: error while creating mbox spool file"); + return DEFER; + } + } +else + { + if ((f_pos = ftell(mime_stream)) < 0) + { + log_write(0, LOG_MAIN|LOG_PANIC, + "regex acl condition: mime_stream: %s", strerror(errno)); + return DEFER; + } + mbox_file = mime_stream; + } + +/* precompile our regexes */ +if (!(re_list_head = compile(*listptr))) + return FAIL; /* no regexes -> nothing to do */ + +/* match each line against all regexes */ +linebuffer = store_get(32767, GET_TAINTED); +while (fgets(CS linebuffer, 32767, mbox_file)) + { + if ( mime_stream && mime_current_boundary /* check boundary */ + && Ustrncmp(linebuffer, "--", 2) == 0 + && Ustrncmp((linebuffer+2), mime_current_boundary, + Ustrlen(mime_current_boundary)) == 0) + break; /* found boundary */ + + if ((ret = matcher(re_list_head, linebuffer, (int)Ustrlen(linebuffer))) == OK) + goto done; + } +/* no matches ... */ + +done: +if (!mime_stream) + (void)fclose(mbox_file); +else + { + clearerr(mime_stream); + if (fseek(mime_stream, f_pos, SEEK_SET) == -1) + { + log_write(0, LOG_MAIN|LOG_PANIC, + "regex acl condition: mime_stream: %s", strerror(errno)); + clearerr(mime_stream); + } + } + +return ret; +} + + +int +mime_regex(const uschar **listptr) +{ +pcre_list *re_list_head = NULL; +FILE *f; +uschar *mime_subject = NULL; +int mime_subject_len = 0; +int ret; + +/* reset expansion variable */ +regex_match_string = NULL; + +/* precompile our regexes */ +if (!(re_list_head = compile(*listptr))) + return FAIL; /* no regexes -> nothing to do */ + +/* check if the file is already decoded */ +if (!mime_decoded_filename) + { /* no, decode it first */ + const uschar *empty = US""; + mime_decode(&empty); + if (!mime_decoded_filename) + { /* decoding failed */ + log_write(0, LOG_MAIN, + "mime_regex acl condition warning - could not decode MIME part to file"); + return DEFER; + } + } + +/* open file */ +if (!(f = fopen(CS mime_decoded_filename, "rb"))) + { + log_write(0, LOG_MAIN, + "mime_regex acl condition warning - can't open '%s' for reading", + mime_decoded_filename); + return DEFER; + } + +/* get 32k memory, tainted */ +mime_subject = store_get(32767, GET_TAINTED); + +mime_subject_len = fread(mime_subject, 1, 32766, f); + +ret = matcher(re_list_head, mime_subject, mime_subject_len); +(void)fclose(f); +return ret; +} + +#endif /* WITH_CONTENT_SCAN */ |