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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 09:44:07 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 09:44:07 +0000 |
commit | 39ce00b8d520cbecbd6af87257e8fb11df0ec273 (patch) | |
tree | 4c21a2674c19e5c44be3b3550b476b9e63d8ae3d /src/header.c | |
parent | Initial commit. (diff) | |
download | exim4-39ce00b8d520cbecbd6af87257e8fb11df0ec273.tar.xz exim4-39ce00b8d520cbecbd6af87257e8fb11df0ec273.zip |
Adding upstream version 4.94.2.upstream/4.94.2upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/header.c')
-rw-r--r-- | src/header.c | 467 |
1 files changed, 467 insertions, 0 deletions
diff --git a/src/header.c b/src/header.c new file mode 100644 index 0000000..cf7a812 --- /dev/null +++ b/src/header.c @@ -0,0 +1,467 @@ +/************************************************* +* Exim - an Internet mail transport agent * +*************************************************/ + +/* Copyright (c) University of Cambridge 1995 - 2016 */ +/* Copyright (c) The Exim Maintainers 2020 */ +/* See the file NOTICE for conditions of use and distribution. */ + + +#include "exim.h" + + +/************************************************* +* Test a header for matching name * +*************************************************/ + +/* This function tests the name of a header. It is made into a function because +it isn't just a string comparison: spaces and tabs are permitted between the +name and the colon. The h->text field should nowadays never be NULL, but check +it just in case. + +Arguments: + h points to the header + name the name to test + len the length of the name + notdel if TRUE, force FALSE for deleted headers + +Returns: TRUE or FALSE +*/ + +BOOL +header_testname(header_line *h, const uschar *name, int len, BOOL notdel) +{ +uschar *tt; +if (h->type == '*' && notdel) return FALSE; +if (h->text == NULL || strncmpic(h->text, name, len) != 0) return FALSE; +tt = h->text + len; +while (*tt == ' ' || *tt == '\t') tt++; +return *tt == ':'; +} + +/* This is a copy of the function above, only that it is possible to pass + only the beginning of a header name. It simply does a front-anchored + substring match. Arguments and Return codes are the same as for + header_testname() above. */ + +BOOL +header_testname_incomplete(header_line *h, const uschar *name, + int len, BOOL notdel) +{ +if (h->type == '*' && notdel) return FALSE; +if (h->text == NULL || strncmpic(h->text, name, len) != 0) return FALSE; +return TRUE; +} + + +/************************************************* +* Add new header backend function * +*************************************************/ + +/* The header_last variable points to the last header during message reception +and delivery; otherwise it is NULL. We add new headers only when header_last is +not NULL. The function may get called sometimes when it is NULL (e.g. during +address verification where rewriting options exist). When called from a filter, +there may be multiple header lines in a single string. + +This is an internal static function that is the common back end to the external +functions defined below. The general interface allows the header to be inserted +before or after a given occurrence of a given header. + +(a) if "name" is NULL, the header is added at the end of all the existing + headers if "after" is true, or at the start if it is false. The "topnot" + flag is not used. + +(b) If "name" is not NULL, the first existing header with that name is sought. + If "after" is false, the new header is added before it. If "after" is true, + a check is made for adjacent headers with the same name, and the new header + is added after the last of them. If a header of the given name is not + found, the new header is added first if "topnot" is true, and at the bottom + otherwise. + +Arguments: + after TRUE for "after", FALSE for "before" + name name if adding at a specific header, else NULL + topnot TRUE to add at top if no header found + type Exim header type character (htype_something) + format sprintf format + ap va_list value for format arguments + +Returns: pointer to header struct (last one, if multiple added) +*/ + +static header_line * +header_add_backend(BOOL after, uschar *name, BOOL topnot, int type, + const char *format, va_list ap) +{ +header_line *h, *new = NULL; +header_line **hptr; + +uschar *p, *q; +uschar * buf = store_get(HEADER_ADD_BUFFER_SIZE, FALSE); +gstring gs = { .size = HEADER_ADD_BUFFER_SIZE, .ptr = 0, .s = buf }; + +if (!header_last) return NULL; + +if (!string_vformat(&gs, SVFMT_REBUFFER, format, ap)) + log_write(0, LOG_MAIN|LOG_PANIC_DIE, "string too long in header_add: " + "%.100s ...", string_from_gstring(&gs)); + +if (gs.s != buf) store_release_above(buf); +gstring_release_unused(&gs); +string_from_gstring(&gs); + +/* Find where to insert this header */ + +if (!name) + if (after) + { + hptr = &header_last->next; + h = NULL; + } + else + { + hptr = &header_list; + + /* header_list->text can be NULL if we get here between when the new + received header is allocated and when it is actually filled in. We want + that header to be first, so skip it for now. */ + + if (!header_list->text) + hptr = &header_list->next; + h = *hptr; + } + +else + { + int len = Ustrlen(name); + + /* Find the first non-deleted header with the correct name. */ + + for (hptr = &header_list; (h = *hptr); hptr = &h->next) + if (header_testname(h, name, len, TRUE)) + break; + + /* Handle the case where no header is found. To insert at the bottom, nothing + needs to be done. */ + + if (!h) + { + if (topnot) + { + hptr = &header_list; + h = header_list; + } + } + + /* Handle the case where a header is found. Check for more if "after" is + true. In this case, we want to include deleted headers in the block. */ + + else if (after) + for (;;) + { + if (!h->next || !header_testname(h, name, len, FALSE)) break; + hptr = &h->next; + h = h->next; + } + } + +/* Loop for multiple header lines, taking care about continuations. At this +point, we have hptr pointing to the link field that will point to the new +header, and h containing the following header, or NULL. */ + +for (p = q = gs.s; *p; p = q) + { + for (;;) + { + q = Ustrchr(q, '\n'); + if (!q) q = p + Ustrlen(p); + if (*(++q) != ' ' && *q != '\t') break; + } + + new = store_get(sizeof(header_line), FALSE); + new->text = string_copyn(p, q - p); + new->slen = q - p; + new->type = type; + new->next = h; + + *hptr = new; + hptr = &new->next; + + if (!h) header_last = new; + } +return new; +} + + +/************************************************* +* Add new header anywhere in the chain * +*************************************************/ + +/* This is an external interface to header_add_backend(). + +Arguments: + after TRUE for "after", FALSE for "before" + name name if adding at a specific header, else NULL + topnot TRUE to add at top if no header found + type Exim header type character (htype_something) + format sprintf format + ... format arguments + +Returns: pointer to header struct added +*/ + +header_line * +header_add_at_position_internal(BOOL after, uschar *name, BOOL topnot, int type, + const char *format, ...) +{ +header_line * h; +va_list ap; +va_start(ap, format); +h = header_add_backend(after, name, topnot, type, format, ap); +va_end(ap); +return h; +} + + +/* Documented external i/f for local_scan */ +void +header_add_at_position(BOOL after, uschar *name, BOOL topnot, int type, + const char *format, ...) +{ +va_list ap; +va_start(ap, format); +(void) header_add_backend(after, name, topnot, type, format, ap); +va_end(ap); +} + +/************************************************* +* Add new header on end of chain * +*************************************************/ + +/* This is now a convenience interface to header_add_backend(). + +Arguments: + type Exim header type character + format sprintf format + ... arguments for the format + +Returns: nothing +*/ + +void +header_add(int type, const char *format, ...) +{ +va_list ap; +va_start(ap, format); +(void) header_add_backend(TRUE, NULL, FALSE, type, format, ap); +va_end(ap); +} + + + +/************************************************* +* Remove (mark as old) a header * +*************************************************/ + +/* This function is used by the filter code; it is also exported in the +local_scan() API. If no header is found, the function does nothing. + +Arguments: + occ the occurrence number for multiply-defined headers + <= 0 means "all"; deleted headers are not counted + name the header name + +Returns: nothing +*/ + +void +header_remove(int occ, const uschar *name) +{ +int hcount = 0; +int len = Ustrlen(name); +for (header_line * h = header_list; h; h = h->next) + if (header_testname(h, name, len, TRUE) && (occ <= 0 || ++hcount == occ)) + { + h->type = htype_old; + if (occ > 0) return; + } +} + + + +/************************************************* +* Check the name of a header * +*************************************************/ + +/* This function scans a table of header field names that Exim recognizes, and +returns the identification of a match. If "resent" is true, the header is known +to start with "resent-". In that case, the function matches only those fields +that are allowed to appear with resent- in front of them. + +Arguments: + h points to the header line + is_resent TRUE if the name starts "Resent-" + +Returns: One of the htype_ enum values, identifying the header +*/ + +int +header_checkname(header_line *h, BOOL is_resent) +{ +uschar *text = h->text; +header_name *bot = header_names; +header_name *top = header_names + header_names_size; + +if (is_resent) text += 7; + +while (bot < top) + { + header_name *mid = bot + (top - bot)/2; + int c = strncmpic(text, mid->name, mid->len); + + if (c == 0) + { + uschar * s = text + mid->len; + if (Uskip_whitespace(&s) == ':') + return (!is_resent || mid->allow_resent)? mid->htype : htype_other; + c = 1; + } + + if (c > 0) bot = mid + 1; else top = mid; + } + +return htype_other; +} + + +/************************************************* +* Scan a header for certain strings * +*************************************************/ + +/* This function is used for the "personal" test. It scans a particular header +line for any one of a number of strings, matched caselessly either as plain +strings, or as regular expressions. If the header line contains a list of +addresses, each match is applied only to the operative part of each address in +the header, and non-regular expressions must be exact matches. + +The patterns can be provided either as a chain of string_item structures, or +inline in the argument list, or both. If there is more than one header of the +same name, they are all searched. + +Arguments: + name header name, including the trailing colon + has_addresses TRUE if the header contains a list of addresses + cond value to return if the header contains any of the strings + strings points to a chain of string_item blocks + count number of inline strings + ... the inline strings + +Returns: cond if the header exists and contains one of the strings; + otherwise !cond +*/ + + +/* First we have a local subroutine to handle a single pattern */ + +static BOOL +one_pattern_match(uschar *name, int slen, BOOL has_addresses, uschar *pattern) +{ +BOOL yield = FALSE; +const pcre *re = NULL; + +/* If the pattern is a regex, compile it. Bomb out if compiling fails; these +patterns are all constructed internally and should be valid. */ + +if (*pattern == '^') re = regex_must_compile(pattern, TRUE, FALSE); + +/* Scan for the required header(s) and scan each one */ + +for (header_line * h = header_list; !yield && h; h = h->next) + { + if (h->type == htype_old || slen > h->slen || + strncmpic(name, h->text, slen) != 0) + continue; + + /* If the header is a list of addresses, extract each one in turn, and scan + it. A non-regex scan must be an exact match for the address. */ + + if (has_addresses) + { + uschar *s = h->text + slen; + + while (!yield && *s) + { + uschar *error, *next; + uschar *e = parse_find_address_end(s, FALSE); + int terminator = *e; + int start, end, domain; + + /* Temporarily terminate the string at the address end while extracting + the operative address within. */ + + *e = 0; + next = parse_extract_address(s, &error, &start, &end, &domain, FALSE); + *e = terminator; + + /* Move on, ready for the next address */ + + s = e; + if (*s == ',') s++; + + /* If there is some kind of syntax error, just give up on this header + line. */ + + if (!next) break; + + /* Otherwise, test for the pattern; a non-regex must be an exact match */ + + yield = !re + ? (strcmpic(next, pattern) == 0) + : (pcre_exec(re, NULL, CS next, Ustrlen(next), 0, PCRE_EOPT, NULL, 0) + >= 0); + } + } + + /* For headers that are not lists of addresses, scan the entire header line, + and just require "contains" for non-regex patterns. */ + + else + { + yield = (re == NULL)? + (strstric(h->text, pattern, FALSE) != NULL) + : + (pcre_exec(re, NULL, CS h->text, h->slen, 0, PCRE_EOPT, NULL, 0) >= 0); + } + } + +return yield; +} + + +/* The externally visible interface */ + +BOOL +header_match(uschar *name, BOOL has_addresses, BOOL cond, string_item *strings, + int count, ...) +{ +va_list ap; +int slen = Ustrlen(name); + +for (string_item * s = strings; s; s = s->next) + if (one_pattern_match(name, slen, has_addresses, s->text)) + return cond; + +va_start(ap, count); +for (int i = 0; i < count; i++) + if (one_pattern_match(name, slen, has_addresses, va_arg(ap, uschar *))) + { + va_end(ap); + return cond; + } +va_end(ap); + +return !cond; +} + +/* End of header.c */ |