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+/*************************************************
+* 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 */
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