[RFC] [PATCH] Let PLUGIN_RAW plugins alter message lengths

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Hi,

I am currently developing a custom plugin for siproxd.  In some cases,
it needs to modify the raw message buffer in order to work around
libosip2's limitations (for example, libosip2 doesn't handle RFC
3966-style URIs correctly, while the upstream proxy I am communicating
with uses those).

However, by doing so I have noticed that the subsequent modified message
gets truncated, even though my code recalculates ticket->raw_buffer_len
correctly.

The issue lies in the fact that the buffer lengths used in the
subsequent checks are no longer valid if these are modified during the
PLUGIN_RAW phase.  Instead, the recalculated buffer lengths within the
ticket should be used.

My attached patch therefore modifies all these checks to use
ticket.raw_buffer and ticket.raw_buffer_len instead of buff and buflen.
This is the only way I know to make this case (and a somewhat ugly one,
I know, hence the [RFC] tag) work correctly.

This patch is designed for siproxd-0.8.0 but might also apply cleanly to
more recent source trees.

Regards,

Marc van der Wal

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	filename="0.8.0-siproxd-perform_checks_on_ticket.patch"

--- src/siproxd.c~	2014-05-14 22:43:31.348725368 +0200
+++ src/siproxd.c	2014-05-14 22:45:22.706674127 +0200
@@ -408,7 +408,7 @@
       /*
        * integrity checks
        */
-      sts=security_check_raw(buff, buflen);
+      sts=security_check_raw(ticket.raw_buffer, ticket.raw_buffer_len);
       if (sts != STS_SUCCESS) {
          DEBUGC(DBCLASS_SIP,"security check (raw) failed");
          continue; /* there are no resources to free */
@@ -417,7 +417,7 @@
       /*
        * Hacks to fix-up some broken headers
        */
-      sts=sip_fixup_asterisk(buff, &buflen);
+      sts=sip_fixup_asterisk(ticket.raw_buffer, &ticket.raw_buffer_len);
 
       /*
        * init sip_msg
@@ -434,10 +434,10 @@
        * Proxy Behavior - Request Validation - Reasonable Syntax
        * (parse the received message)
        */
-      sts=sip_message_parse(ticket.sipmsg, buff, buflen);
+      sts=sip_message_parse(ticket.sipmsg, ticket.raw_buffer, ticket.raw_buffer_len);
       if (sts != 0) {
          ERROR("sip_message_parse() failed... this is not good");
-         DUMP_BUFFER(-1, buff, buflen);
+         DUMP_BUFFER(-1, ticket.raw_buffer, ticket.raw_buffer_len);
          goto end_loop; /* skip and free resources */
       }
 
@@ -447,7 +447,7 @@
       sts=security_check_sip(&ticket);
       if (sts != STS_SUCCESS) {
          ERROR("security_check_sip() failed... this is not good");
-         DUMP_BUFFER(-1, buff, buflen);
+         DUMP_BUFFER(-1, ticket.raw_buffer, ticket.raw_buffer_len);
          goto end_loop; /* skip and free resources */
       }
 

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