+
+/*************************************************
+* Extract a Message-ID *
+*************************************************/
+
+/* This function is used to extract message ids from In-Reply-To: and
+References: header lines.
+
+Arguments:
+ str pointer to the start of the message-id
+ yield put pointer to the message id (in dynamic memory) here
+ error put error message here on failure
+
+Returns: points after the processed message-id or NULL on error
+*/
+
+uschar *
+parse_message_id(uschar *str, uschar **yield, uschar **error)
+{
+uschar *domain = NULL;
+uschar *id;
+
+str = skip_comment(str);
+if (*str != '<')
+ {
+ *error = US"Missing '<' before message-id";
+ return NULL;
+ }
+
+/* Getting a block the size of the input string will definitely be sufficient
+for the answer, but it may also be very long if we are processing a header
+line. Therefore, take care to release unwanted store afterwards. */
+
+id = *yield = store_get(Ustrlen(str) + 1);
+*id++ = *str++;
+
+str = read_addr_spec(str, id, '>', error, &domain);
+
+if (*error == NULL)
+ {
+ if (*str != '>') *error = US"Missing '>' after message-id";
+ else if (domain == NULL) *error = US"domain missing in message-id";
+ }
+
+if (*error != NULL)
+ {
+ store_reset(*yield);
+ return NULL;
+ }
+
+while (*id != 0) id++;
+*id++ = *str++;
+*id++ = 0;
+store_reset(id);
+
+str = skip_comment(str);
+return str;
+}
+
+
+
+