PQ41197: GETHOSTBYNAME() FAILS WHEN TRYING TO RESOLVE THE HOST NAME 00/09/26 PTF PECHANGE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• The gethostbyname() call tries to resolve the host name through
  a name server. If a name server is not present or is unable to
  resolve the hostname, the first file found of /etc/hosts,
  yourhlq.HOSTS.SITEINFO, or tcphlq.HOSTS.SITEINFO is used. After
  PQ37436 the res_send funtion returns success regardless of
  whether an answer was returned from the nameserver or not. So
  when gethostbyname tries to evaluate the answer to determine
  if the call succeeded, it may branch arround the local
  resolution due to the incorrect return value from res_send.
  This problem also causes abends in the follwoing functions:
  dn_skipname , dn_expand , and getshort
  

Local fix

• Back off PTFs for PQ37436:
  Release 608   : UQ42958
  Release 609   : UQ42959
  Release 703   : UQ42960
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users of gethostbyname() and res_send().     *
  ****************************************************************
  * PROBLEM DESCRIPTION: The C Run-Time Library function         *
  *                      res_send() returns an incorrect value   *
  *                      if there is no nameserver present.      *
  *                      This causes functions that use          *
  *                      res_send(), such as gethostbyname(), to *
  *                      return an incorrect result.             *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  The function res_send() needs to be modified to return -1 if
  there is no nameserver present.  In addition, if a connection
  had been made to a nameserver but an error was encountered
  without subsequently resolving from another nameserver, the
  answer should be returned along with the correct value from the
  first nameserver that returned an error while resolving.
  

Problem conclusion

• The C Run-Time Library function res_send() has been modified to
  return -1 if a nameserver is not present.  In addition, the
  answer and return value returned from res_send() is from the
  first nameserver that returns an error if no subsquent
  nameserver can resolve the input.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  UQ46969 UQ46970 UQ46971 122PC5Ÿ

Modules/Macros

• CELHRSND EDC4033F
  

Fix information

• Fixed component name

  LE C LIBRARY

• Fixed component ID

  568819805

Applicable component levels

• R608 PSY UQ46969

     UP00/09/22 P F009 «

• R609 PSY UQ46970

     UP00/09/22 P F009 «

• R703 PSY UQ46971

     UP00/09/22 P F009 «

Fix is available

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