getpeername

Makefile

@@ -0,0 +1,4 @@
+all: getpeername
+
+clean:
+	rm getpeername

getpeername.c

@@ -0,0 +1,39 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <errno.h>
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <netdb.h>
+
+int main(int argc, char **argv) {
+    struct sockaddr_storage peer;
+    socklen_t peersize = sizeof peer;
+    char hostname[256];
+    char portname[32];
+
+    if (getpeername(0, (struct sockaddr * restrict)&peer, &peersize) < 0) {
+	perror("getpeername");
+	exit(1);
+    }
+
+    int v;
+    v = getnameinfo((struct sockaddr * restrict)&peer,
+        sizeof(struct sockaddr_storage),
+        hostname,
+        sizeof(hostname),
+        portname,
+        sizeof(portname),
+        NI_NUMERICHOST | NI_NUMERICSERV);
+
+    if (v < 0) {
+        printf("getnameinfo: %s\n", gai_strerror(v));
+        exit(1);
+    }
+
+    printf("%s %s\n", hostname, portname);
+
+    return 0;
+}