Build: Auto-detect available libraries by default

If neither OFF or ON is defined, enable if auto-detected.

CMakeLists.txt

@@ -18,11 +18,38 @@ include_directories(
   ${PROJECT_BINARY_DIR}
   ${PROJECT_SOURCE_DIR}/include)
 
+function(optional_library LIB_NAME DESCRIPTION)
+  set(USE_${LIB_NAME} "DEFAULT" CACHE STRING "${DESCRIPTION}")
+
+  string(TOLOWER "${LIB_NAME}" LIB_LOWER)
+  if(USE_${LIB_NAME} STREQUAL "ON" OR USE_${LIB_NAME} STREQUAL "1")
+    find_library(${LIB_NAME}_LIBRARY ${LIB_LOWER})
+    set(USE_${LIB_NAME} 1)
+  elseif(USE_${LIB_NAME} STREQUAL "OFF" OR USE_${LIB_NAME} STREQUAL "0")
+    set(USE_${LIB_NAME} 0)
+  else()
+    find_library(${LIB_NAME}_LIBRARY ${LIB_LOWER})
+    if(${LIB_NAME}_LIBRARY)
+      message(STATUS "${LIB_NAME} is enabled")
+      set(USE_${LIB_NAME} 1 PARENT_SCOPE)
+    else()
+      message(STATUS "${LIB_NAME} is disabled")
+      set(USE_${LIB_NAME} 0 PARENT_SCOPE)
+    endif()
+  endif()
+endfunction()
+
+optional_library(SCTP "Build with SCTP support")
+optional_library(PCAP "Build with PCAP playback support")
+optional_library(GSL "Build with improved statistical support")
+set(USE_SSL "DEFAULT" CACHE STRING "Build with SIPS support")
+if(USE_SSL STREQUAL "ON" OR USE_SSL STREQUAL "1")
+  set(USE_SSL 1)
+elseif(USE_SSL STREQUAL "OFF" OR USE_SSL STREQUAL "0")
+  set(USE_SSL 0)
+endif()
+
 option(BUILD_STATIC "Build a statically-linked binary" OFF)
-option(USE_SSL "Build with SIPS support" OFF)
-option(USE_SCTP "Build with SCTP support" OFF)
-option(USE_PCAP "Build with PCAP playback support" OFF)
-option(USE_GSL "Build with improved statistical support" ON)
 option(USE_LOCAL_IP_HINTS "Build with local ip hints priority" OFF)
 
 file(GLOB all_SRCS
@@ -58,11 +85,6 @@ list(REMOVE_ITEM all_SRCS
 list(REMOVE_ITEM all_SRCS
   "${PROJECT_SOURCE_DIR}/src/sipp.cpp")
 
-if(NOT USE_SSL)
-  list(REMOVE_ITEM all_SRCS
-    "${PROJECT_SOURCE_DIR}/src/sslsocket.cpp")
-endif(NOT USE_SSL)
-
 if(NOT USE_PCAP)
   list(REMOVE_ITEM all_SRCS
     "${PROJECT_SOURCE_DIR}/src/prepare_pcap.c")
@@ -94,7 +116,16 @@ if(USE_SSL)
         set(WOLFSSL_FOUND True)
       endif()
     endif()
-    if(NOT OPENSSL_FOUND AND NOT WOLFSSL_FOUND)
+  endif()
+  if(OPENSSL_FOUND OR WOLFSSL_FOUND)
+    if(USE_SSL STREQUAL "DEFAULT")
+      message(STATUS "Found ${SSL_LIBRARIES}; enabling sips support")
+    endif()
+  else()
+    if(USE_SSL STREQUAL "DEFAULT")
+      message(STATUS "Neither OpenSSL nor WolfSSL was found; disabling sips support")
+      set(USE_SSL 0)
+    else()
       message(FATAL_ERROR "Neither OpenSSL nor WolfSSL was found; please install a devel package")
     endif()
   endif()
@@ -103,6 +134,12 @@ if(USE_SSL)
   elseif(WOLFSSL_FOUND)
     add_definitions("-DUSE_TLS" "-DUSE_WOLFSSL" "-DOPENSSL_ALL")
   endif()
+
+if(NOT USE_SSL)
+  list(REMOVE_ITEM all_SRCS
+    "${PROJECT_SOURCE_DIR}/src/sslsocket.cpp")
+endif(NOT USE_SSL)
+
 endif()
 
 if(USE_PCAP)
@@ -114,10 +151,7 @@ if(USE_LOCAL_IP_HINTS)
 endif(USE_LOCAL_IP_HINTS)
 
 if(USE_GSL)
-  find_library(GSL_LIBRARY gsl)
-  if(GSL_LIBRARY)
-    add_definitions("-DHAVE_GSL")
-  endif(GSL_LIBRARY)
+  add_definitions("-DHAVE_GSL")
 endif(USE_GSL)
 
 if(USE_SCTP)
@@ -228,19 +262,19 @@ if(CYGWIN)
   add_definitions("-D_GNU_SOURCE")
 endif(CYGWIN)
 
-if(USE_GSL AND GSL_LIBRARY)
+if(USE_GSL)
   target_link_libraries(sipp gsl gslcblas)
   target_link_libraries(sipp_unittest gsl gslcblas)
-endif(USE_GSL AND GSL_LIBRARY)
+endif(USE_GSL)
 
-if(USE_SSL AND SSL_LIBRARIES)
+if(USE_SSL)
   target_link_libraries(sipp ${SSL_LIBRARIES})
   target_link_libraries(sipp_unittest ${SSL_LIBRARIES})
   if(SSL_INCLUDE_DIRS)
     target_include_directories(sipp SYSTEM PUBLIC ${SSL_INCLUDE_DIRS})
     target_include_directories(sipp_unittest SYSTEM PUBLIC ${SSL_INCLUDE_DIRS})
   endif(SSL_INCLUDE_DIRS)
-endif(USE_SSL AND SSL_LIBRARIES)
+endif(USE_SSL)
 
 if(USE_PCAP)
   target_link_libraries(sipp pcap)