SIPSorcery.SIP.SIPViaHeader.ParseSIPViaHeader C# (CSharp) Method

        public static SIPViaHeader[] ParseSIPViaHeader(string viaHeaderStr)
        {
            List<SIPViaHeader> viaHeadersList = new List<SIPViaHeader>();

            if (!viaHeaderStr.IsNullOrBlank())
            {
                viaHeaderStr = viaHeaderStr.Trim();

                // Multiple Via headers can be contained in a single line by separating them with a comma.
                string[] viaHeaders = SIPParameters.GetKeyValuePairsFromQuoted(viaHeaderStr, ',');

                foreach (string viaHeaderStrItem in viaHeaders)
                {
                    if (viaHeaderStrItem == null || viaHeaderStrItem.Trim().Length == 0)
                    {
                        throw new SIPValidationException(SIPValidationFieldsEnum.ViaHeader, "No Contact address.");
                    }
                    else
                    {
                        SIPViaHeader viaHeader = new SIPViaHeader();
                        string header = viaHeaderStrItem.Trim();

                        int firstSpacePosn = header.IndexOf(" ");
                        if (firstSpacePosn == -1)
                        {
                            throw new SIPValidationException(SIPValidationFieldsEnum.ViaHeader, "No Contact address.");
                        }
                        else
                        {
                            string versionAndTransport = header.Substring(0, firstSpacePosn);
                            viaHeader.Version = versionAndTransport.Substring(0, versionAndTransport.LastIndexOf('/'));
                            viaHeader.Transport = SIPProtocolsType.GetProtocolType(versionAndTransport.Substring(versionAndTransport.LastIndexOf('/') + 1));

                            string nextField = header.Substring(firstSpacePosn, header.Length - firstSpacePosn).Trim();

                            int delimIndex = nextField.IndexOf(';');
                            string contactAddress = null;

                            // Some user agents include branch but have the semi-colon missing, that's easy to cope with by replacing "branch" with ";branch".
                            if (delimIndex == -1 && nextField.Contains(m_branchKey))
                            {
                                nextField = nextField.Replace(m_branchKey, ";" + m_branchKey);
                                delimIndex = nextField.IndexOf(';');
                            }

                            if (delimIndex == -1)
                            {
                                //logger.Warn("Via header missing semi-colon: " + header + ".");
                                //parserError = SIPValidationError.NoBranchOnVia;
                                //return null;
                                contactAddress = nextField.Trim();
                            }
                            else
                            {
                                contactAddress = nextField.Substring(0, delimIndex).Trim();
                                viaHeader.ViaParameters = new SIPParameters(nextField.Substring(delimIndex, nextField.Length - delimIndex), m_paramDelimChar);
                            }

                            if (contactAddress == null || contactAddress.Trim().Length == 0)
                            {
                                // Check that the branch parameter is present, without it the Via header is illegal.
                                //if (!viaHeader.ViaParameters.Has(m_branchKey))
                                //{
                                //    logger.Warn("Via header missing branch: " + header + ".");
                                //    parserError = SIPValidationError.NoBranchOnVia;
                                //    return null;
                                //}

                                throw new SIPValidationException(SIPValidationFieldsEnum.ViaHeader, "No Contact address.");
                            }

                            // Parse the contact address.
                            int colonIndex = contactAddress.IndexOf(m_hostDelimChar);
                            if (colonIndex != -1)
                            {
                                viaHeader.Host = contactAddress.Substring(0, colonIndex);

                                if (!Int32.TryParse(contactAddress.Substring(colonIndex + 1), out viaHeader.Port))
                                {
                                    throw new SIPValidationException(SIPValidationFieldsEnum.ViaHeader, "Non-numeric port for IP address.");
                                }
                                else if (viaHeader.Port > SIPConstants.MAX_SIP_PORT)
                                {
                                    throw new SIPValidationException(SIPValidationFieldsEnum.ViaHeader, "The port specified in a Via header exceeded the maximum allowed.");
                                }
                            }
                            else
                            {
                                viaHeader.Host = contactAddress;
                            }

                            viaHeadersList.Add(viaHeader);
                        }
                    }
                }
            }

            if (viaHeadersList.Count > 0)
            {
                return viaHeadersList.ToArray();
            }
            else
            {
                throw new SIPValidationException(SIPValidationFieldsEnum.ViaHeader, "Via list was empty."); ;
            }
        }