jrtplib can't retrieve login name解决方案-摩杜云开发者社区

场景

arm linux版本程序启动调用jrtplib报错如上，导致建立rtpsession失败

原因分析

RTPSession::CreateCNAME 这个函数会从系统调用里获取登陆名称，然后填充RTCP报文中的CNAME字段，但是一般的板子由于内核和文件系统的原因都没有登录名称

int RTPSession::CreateCNAME(uint8_t *buffer,size_t *bufferlength,bool resolve)
{
#ifndef WIN32
  bool gotlogin = true;
#ifdef RTP_SUPPORT_GETLOGINR
  buffer[0] = 0;
  if (getlogin_r((char *)buffer,*bufferlength) != 0)
    gotlogin = false;
  else
  {
    if (buffer[0] == 0)
      gotlogin = false;
  }
  
  if (!gotlogin) // try regular getlogin
  {
    char *loginname = getlogin();
    if (loginname == 0)
      gotlogin = false;
    else
      strncpy((char *)buffer,loginname,*bufferlength);
  }
#else
  char *loginname = getlogin();
  if (loginname == 0)
    gotlogin = false;
  else
    strncpy((char *)buffer,loginname,*bufferlength);
#endif // RTP_SUPPORT_GETLOGINR
  if (!gotlogin)
  {
    char *logname = getenv("LOGNAME");
    if (logname == 0)
      return ERR_RTP_SESSION_CANTGETLOGINNAME;
    strncpy((char *)buffer,logname,*bufferlength);
  }
#else // Win32 version

#ifndef _WIN32_WCE
  DWORD len = *bufferlength;
  if (!GetUserName((LPTSTR)buffer,&len))
    RTP_STRNCPY((char *)buffer,"unknown",*bufferlength);
#else 
  RTP_STRNCPY((char *)buffer,"unknown",*bufferlength);
#endif // _WIN32_WCE
  
#endif // WIN32
  buffer[*bufferlength-1] = 0;

  size_t offset = strlen((const char *)buffer);
  if (offset < (*bufferlength-1))
    buffer[offset] = (uint8_t)'@';
  offset++;

  size_t buflen2 = *bufferlength-offset;
  int status;
  
  if (resolve)
  {
    if ((status = rtptrans->GetLocalHostName(buffer+offset,&buflen2)) < 0)
      return status;
    *bufferlength = buflen2+offset;
  }
  else
  {
    char hostname[1024];
    
    RTP_STRNCPY(hostname,"localhost",1024); // just in case gethostname fails

    gethostname(hostname,1024);
    RTP_STRNCPY((char *)(buffer+offset),hostname,buflen2);

    *bufferlength = offset+strlen(hostname);
  }
  if (*bufferlength > RTCP_SDES_MAXITEMLENGTH)
    *bufferlength = RTCP_SDES_MAXITEMLENGTH;
  return 0;
}

尝试方案

export LOGNAME=root

运行可执行环境

最终方案

强制指定CNAME，直接返回

int RTPSession::CreateCNAME(uint8_t *buffer,size_t *bufferlength,bool resolve)
{
#ifndef WIN32
  bool gotlogin = true;
  strncpy((char *)buffer, "fengyuzaitu", *bufferlength);
  return 0;
#ifdef RTP_SUPPORT_GETLOGINR