diff options
Diffstat (limited to 'transact.c')
| -rw-r--r-- | transact.c | 49 |
1 files changed, 26 insertions, 23 deletions
@@ -29,6 +29,7 @@ #ifdef HAVE_NET_SOCKET_H #include <net/socket.h> #endif +#include "md5.h" #include "i18n.h" #include "socket.h" @@ -406,10 +407,8 @@ int readheaders(int sock, if (delivered_to) free(delivered_to); - /* initially, no message ID */ - if (ctl->thisid) - free(ctl->thisid); - ctl->thisid = NULL; + /* initially, no message digest */ + memset(ctl->thisid, '\0', sizeof(ctl->thisid)); msgblk.headers = received_for = delivered_to = NULL; from_offs = reply_to_offs = resent_from_offs = app_from_offs = @@ -605,10 +604,6 @@ int readheaders(int sock, if (linelen != strlen (line)) has_nuls = TRUE; - /* save the message's ID, we may use it for killing duplicates later */ - if (MULTIDROP(ctl) && !strncasecmp(line, "Message-ID:", 11)) - ctl->thisid = xstrdup(line); - /* * The University of Washington IMAP server (the reference * implementation of IMAP4 written by Mark Crispin) relies @@ -735,7 +730,7 @@ int readheaders(int sock, * make sure we never try to rewrite such a blank Return-Path. We * handle this with a check for <> in the rewrite logic above. * - * Also, if an email has multiple Return-Path: statement, we only + * Also, if an email has multiple Return-Path: headers, we only * read the first occurance, as some spam email has more than one * Return-Path. * @@ -890,6 +885,8 @@ int readheaders(int sock, if (refuse_mail) return(PS_REFUSED); /* + * This is the duplicate-message killer code. + * * When mail delivered to a multidrop mailbox on the server is * addressed to multiple people on the client machine, there will * be one copy left in the box for each recipient. This is not a @@ -901,10 +898,10 @@ int readheaders(int sock, * if the mail is addressed to N people, each recipient will * get N copies. This is bad when N > 1. * - * Foil this by suppressing all but one copy of a message with - * a given Message-ID. The accept_count test ensures that - * multiple pieces of email with the same Message-ID, each - * with a *single* addressee (the N == 1 case), won't be + * Foil this by suppressing all but one copy of a message with a + * given set of headers. The accept_count test ensures + * that multiple pieces of email with the same Message-ID, each + * with a *single* addressee (the N == 1 case), won't be * suppressed. * * Note: This implementation only catches runs of successive @@ -918,20 +915,26 @@ int readheaders(int sock, * to break it in a way that blackholed mail. Better to pass * the occasional duplicate than to do that... */ - if (!received_for && env_offs == -1 && !delivered_to) + if (MULTIDROP(ctl)) { - if (ctl->lastid && ctl->thisid && !strcasecmp(ctl->lastid, ctl->thisid)) + MD5_CTX context; + + MD5Init(&context); + MD5Update(&context, msgblk.headers, strlen(msgblk.headers)); + MD5Final(ctl->thisid, &context); + + if (!received_for && env_offs == -1 && !delivered_to) { - if (accept_count > 1) + /* + * Hmmm...can MD5 ever yield all zeroes as a hash value? + * If so there is a one in 18-quadrillion chance this + * code will incorrectly nuke the first message. + */ + if (memcmp(ctl->lastid, ctl->thisid, sizeof(ctl->lastid))) + ctl->lastid = ctl->thisid; + else if (accept_count > 1) return(PS_REFUSED); } - else - { - if (ctl->lastid) - free(ctl->lastid); - ctl->lastid = ctl->thisid; - ctl->thisid = NULL; - } } /* |