Non-platform-specific detection of TCP_CONGESTION socket option.

Rather than checking for anything Linux-specific at configure-time,
see if TCP_CONGESTION is defined in <netinet/tcp.h> and if so define
a CPP variable HAVE_TCP_CONGESTION, which we then use to enable
conditional compilation of the code for this feature.

configure.ac

@@ -50,4 +50,17 @@ AC_C_CONST
 AC_CHECK_HEADERS([netinet/sctp.h],
 		 AC_DEFINE([HAVE_SCTP], [1], [Have SCTP support.]))
 
+# Check for TCP_CONGESTION sockopt (believed to be Linux only)
+AC_CACHE_CHECK([TCP_CONGESTION socket option],
+[iperf3_cv_header_tcp_congestion],
+AC_EGREP_CPP(yes,
+[#include <netinet/tcp.h>
+#ifdef TCP_CONGESTION
+  yes
+#endif
+],iperf3_cv_header_tcp_congestion=yes,iperf3_cv_header_tcp_congestion=no))
+if test "x$iperf3_cv_header_tcp_congestion" = "xyes"; then
+    AC_DEFINE([HAVE_TCP_CONGESTION], [1], [Have TCP_CONGESTION sockopt.])
+fi
+
 AC_OUTPUT([Makefile src/Makefile examples/Makefile])

src/iperf_api.c

@@ -570,9 +570,9 @@ iperf_parse_arguments(struct iperf_test *test, int argc, char **argv)
         {"affinity", required_argument, NULL, 'A'},
 #endif
         {"title", required_argument, NULL, 'T'},
-#if defined(linux) && defined(TCP_CONGESTION)
+#if defined(HAVE_TCP_CONGESTION)
         {"linux-congestion", required_argument, NULL, 'C'},
-#endif
+#endif /* HAVE_TCP_CONGESTION */
 #if defined(HAVE_SCTP)
         {"sctp", no_argument, NULL, OPT_SCTP},
 #endif
@@ -792,13 +792,13 @@ iperf_parse_arguments(struct iperf_test *test, int argc, char **argv)
 		client_flag = 1;
                 break;
 	    case 'C':
-#if defined(linux) && defined(TCP_CONGESTION)
+#if defined(HAVE_TCP_CONGESTION)
 		test->congestion = strdup(optarg);
 		client_flag = 1;
-#else /* linux */
+#else /* HAVE_TCP_CONGESTION */
 		i_errno = IEUNIMP;
 		return -1;
-#endif /* linux */
+#endif /* HAVE_TCP_CONGESTION */
 		break;
 	    case 'd':
 		test->debug = 1;

src/iperf_tcp.c

@@ -20,6 +20,7 @@
 #include <sys/time.h>
 #include <sys/select.h>
 
+#include "config.h"
 #include "iperf.h"
 #include "iperf_api.h"
 #include "iperf_tcp.h"
@@ -196,7 +197,7 @@ iperf_tcp_listen(struct iperf_test *test)
 	    }
 	    printf("SO_SNDBUF is %u\n", opt);
 	}
-#if defined(linux) && defined(TCP_CONGESTION)
+#if defined(HAVE_TCP_CONGESTION)
 	if (test->congestion) {
 	    if (setsockopt(s, IPPROTO_TCP, TCP_CONGESTION, test->congestion, strlen(test->congestion)) < 0) {
 		close(s);
@@ -205,7 +206,7 @@ iperf_tcp_listen(struct iperf_test *test)
 		return -1;
 	    } 
 	}
-#endif
+#endif /* HAVE_TCP_CONGESTION */
         opt = 1;
         if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) < 0) {
 	    saved_errno = errno;

src/locale.c

@@ -106,9 +106,9 @@ const char usage_longstr[] = "Usage: iperf [-s|-c host] [options]\n"
                            "  -R, --reverse             run in reverse mode (server sends, client receives)\n"
                            "  -w, --window    #[KMG]    TCP window size (socket buffer size)\n"
                            "  -B, --bind      <host>    bind to a specific interface\n"
-#if defined(linux)
+#if defined(HAVE_TCP_CONGESTION)
                            "  -C, --linux-congestion <algo>  set TCP congestion control algorithm (Linux only)\n"
-#endif
+#endif /* HAVE_TCP_CONGESTION */
                            "  -M, --set-mss   #         set TCP maximum segment size (MTU - 40 bytes)\n"
                            "  -N, --nodelay             set TCP no delay, disabling Nagle's Algorithm\n"
                            "  -4, --version4            only use IPv4\n"