Sip headers manipulation

Revision as of 07:13, 16 August 2020

The behavior 'SIP headers manipulation' allows the SBC users to freely add ,remove and modify the sip headers when SBC forwards the received invite, 18x and 200 sip messages (there are limitations, please refer to the limitations section below).

Configuration:

To use the behavior, you need to select the option "Enable SIP headers manipulation" under the path "Gateway -> Advanced Parameters" and use the filter script "sip_headers_manipulation.rb" in routing script setting.

Usage:

The manipulation actions are based on what are defined in "sip_headers_manipulation.rb" dynamically or statically. In sip_headers_manipulation.rb, there is filter_sip_headers_manipulation that should be applied as 'after filter' in main script and need to use call[:manipulation] to save what you want SBC to do regarding headers manipulation. An example is :

 def filter_sip_headers_manipulation params
   
   # The following 4 lines are needed to initialize the hash table
   call = params[ :call ]
   call[:manipulation] = {}
   call[:manipulation][:invite] = {}
   call[:manipulation]["18x"] = {}
   call[:manipulation]["200"] = {}
   
   # Will remove "P-Charging-Vector" header from the the invite if exists
   call[:manipulation][:invite]["P-Charging-Vector"] = "todelete"
   # Will add or modify "banana" and set its value to "red" header from the invite
   call[:manipulation][:invite][:banana] = "red"
   # Will add or modify "salad" and set its value to "blue" header from the invite
   call[:manipulation][:invite][:salad] = "blue"
   
   # Will add or modify "P-Charging-Vector" and set its value to "PCV" header from the 18x
   call[:manipulation]["18x"]["P-Charging-Vector"] = "PCV"
   # Will add or modify "banana" and set its value to "yellow" header from the 18x
   call[:manipulation]["18x"][:banana] = "yellow"
   # Will add or modify "salad" and set its value to "green" header from the 18x
   call[:manipulation]["18x"][:salad] = "green"
   
   #if hash value begins with matchandreplace, it means the header has several possible values
   #we will try to compare the received value with settings and use the corresponding replacement
   #the following settings for P-Early-Media means if the received value includes string inactive, JF will be used as header value,
   #if the received value includes string sendrecv, inactive will be used as header value
   call[:manipulation]["18x"]["P-Early-Media"] = "matchandreplace:inactive|JF,sendrecv|inactive"
   
   #we also support regex for replacing header value, the format is "regex:pattern|stringtouse"
   #the setting example is like  call[:manipulation]["18x"]["P-Early-Media"] = "regex:pattern|JF"
   #it means if the pattern exists in the received value, all the occurrences of pattern will be replaced by string JF
   #don't like "matchandreplace:inactive|JF,sendrecv|inactive", we don't support several possible patterns for now
   

   call[:manipulation]["200"]["P-Charging-Vector"] = "PCV"
   call[:manipulation]["200"][:banana] = "yellow"
   call[:manipulation]["200"][:TEST] = "STXIE"
   
   params
 end 
   
 

Limitations:

1. 'SIP headers manipulation' can only affect SIP headers who are not already modified/generated by the other SBC behaviors, see example below.
2. Header values are viewed as a constant string, the routing script cannot pass variable to SBC.
3. If the manipulated header is already present, it will be overwritten.
4. Manipulate headers hash can only be set once per call (on the incoming invite message). It is not possible to update the hash later during the call.
5. SIP header in Re-invite and 200 OK attached to Re-invite cannot be affected by this behavior.

Headers that cannot be used in 'SIP headers manipulation':

 Accept
 Accept-Contact
 Accept-Encoding
 Accept-Language
 Alert-Info
 Allow
 Allow-Events
 Also
 Anonymity
 Authentication-Info
 Authorization
 Call-ID
 Call-Info
 Contact
 Content-Disposition
 Content-Encoding
 Content-Language
 Content-Length
 Content-Type
 CSeq
 Date
 Encryption
 Error-Info
 Event
 Expires
 From
 In-Reply-To
 Max-Forwards
 MIME-version
 Min-Expires
 Min-SE
 Organization
 P-Asserted-Identity
 P-Media-Authorization
 P-Preferred-Identity
 Priority
 Privacy
 Proxy-Authenticate
 Proxy-Authorization
 Proxy-Require
 RAck
 Reason
 Record-Route
 Refer-To
 Referred-By
 Reject-Contact
 Remote-Party-ID
 Replaces
 Reply-To
 Request-Disposition
 Require
 Response-Key
 Retry-After
 Route
 RPID-Privacy
 RSeq
 Security-Client
 Security-Server
 Security-Verify
 Server
 Service-Route
 Session-Expires
 Subject
 Subscription-State
 Supported
 Timestamp
 To
 Unsupported
 User-Agen
 Via
 Warning
 WWW-Authenticate