first commit

diff --git a/makefile b/makefile
new file mode 100644 (file)
index 0000000..d0ad137
--- /dev/null
+++ b/makefile
@@ -0,0 +1,27 @@
+#
+#  Project overhosts
+#
+
+VER=0.0.1
+EXE=overhosts.so test
+OBJ=overhosts.o
+PKGNAME=overhosts
+TARGET=$(EXE)
+
+CC=gcc
+
+ALL: $(TARGET)
+
+overhosts.so: overhosts.c overhosts.h
+       $(CC) -Wall -fPIC -shared -ldl -o $@ $<
+
+test: test.c
+       $(CC) -Wall -g -ggdb -o $@ $<
+
+clean:
+       rm -f $(EXE) $(OBJ) *~ $(TARGET)
+
+pkg:
+       tar -zcv --transform="s,^,$(PKGNAME)-$(VER)/,"  -f ../$(PKGNAME)_$(VER).tgz *
+
+.PHONY: clean pkg ALL

diff --git a/overhosts.c b/overhosts.c
new file mode 100644 (file)
index 0000000..a23a5cf
--- /dev/null
+++ b/overhosts.c
@@ -0,0 +1,173 @@
+/* 
+ *  overhosts.c
+ * 
+ *  Copyright (C) 2012 
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABLILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details. You should have received a
+ * copy of the GNU General Public License along with this program; if
+ * not, write to the Free Software Foundation, Inc, 59 Temple Place - 
+ * Suite 330, Boston, MA 02111-1307, USA.
+ * 
+ */
+
+/*
+  compile like this:
+
+  gcc -c -fPIC preload_open.c
+  ld -shared -o preload_open.so preload_open.o -ldl
+  
+  export LD_PRELOAD=/etc/magic/preload_open.so 
+  myapp ARGS
+
+*/
+
+
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <dlfcn.h>
+#include <fcntl.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <signal.h>
+#include <string.h>
+#include <netdb.h>
+
+#include "overhosts.h"
+
+void  __attribute__ ((constructor)) overhosts_init(void);
+
+struct hostent *(* ohreal_gethostbyname)(const char *name) = NULL;
+struct hostent *(* ohreal_gethostbyname2)(const char *name, int af) = NULL;
+int (*ohreal_getaddrinfo)(const char *node, const char *service,
+                       const struct addrinfo *hints,
+                       struct addrinfo **res) = NULL;
+// void (* ohreal_freeaddrinfo)(struct addrinfo *res) = NULL;
+#if 0
+static struct hostent ohreal_he = { "bernoulli", 
+                                     (char *[]){ NULL }, 
+                                     AF_INET, 
+                                     4,
+                                     (char *[]){ "\x7f\x00\x00\x01", NULL }
+};
+#endif
+
+/*
+static struct addrinfo ohreal_ai = {
+    
+               int              ai_flags;
+               int              ai_family;
+               int              ai_socktype;
+               int              ai_protocol;
+               size_t           ai_addrlen;
+               struct sockaddr *ai_addr;
+               char            *ai_canonname;
+               struct addrinfo *ai_next;
+           };
+
+*/  
+
+void  __attribute__ ((constructor)) overhosts_init(void)
+{
+    ohreal_gethostbyname  = dlsym((void *)-1, "gethostbyname");
+    // printf("PREINTT\n");
+    ohreal_gethostbyname2 = dlsym((void *)-1, "gethostbyname2");
+    ohreal_getaddrinfo    = dlsym((void *)-1, "getaddrinfo");
+    // printf("INITT\n");
+}
+
+static int is_an_alias(const char *name);
+
+static int is_an_alias(const char *name)
+{
+    char *alias, *p, *e;
+    char bf[4096];
+
+    if ((alias = getenv("OVERHOSTS_ALIASES")) == NULL) {
+        // printf("fuori1 [%s]\n", name);
+        return 0;
+    }
+
+    strcpy(bf, "|");
+    strcat(bf, name);
+
+    // printf("in1 [%s][%s]\n", bf, name);
+
+    if (((p = strstr(alias, bf)) != NULL) || ((p = strstr(alias, name)) && p == alias)) {
+        e = p+strlen(name);
+        if (p > alias)
+            e++;
+        // printf("in2 [%s][%c]\n", bf, *e);
+        if (*e == '\0' || *e == '|') {
+            // printf("fuori2 [%s]\n", name);
+            return 1;
+        }
+    }
+    
+    return 0;
+}
+       
+        
+
+// struct hostent *gethostbyname(const char *name);
+struct hostent *gethostbyname2(const char *name, int af);
+
+struct hostent *gethostbyname2(const char *name, int af)
+{
+    char *real;
+    if (is_an_alias(name) && (real = getenv("OVERHOSTS_REAL")) != NULL) {
+        return (gethostbyname2(real, af));
+    }
+    else {
+        return (gethostbyname2(name, af));
+    }
+}
+
+// struct hostent *gethostbyname(const char *name);
+struct hostent *gethostbyname(const char *name);
+
+struct hostent *gethostbyname(const char *name)
+{
+    char *real;
+    if (is_an_alias(name) && (real = getenv("OVERHOSTS_REAL")) != NULL) {
+        return (gethostbyname(real));
+    }
+    else {
+        return (gethostbyname(name));
+    }
+}
+
+int getaddrinfo(const char *node, const char *service,
+                const struct addrinfo *hints,
+                struct addrinfo **res);
+
+int getaddrinfo(const char *node, const char *service,
+                const struct addrinfo *hints,
+                struct addrinfo **res)
+{
+    char *real;
+
+    if (is_an_alias(node) && (real = getenv("OVERHOSTS_REAL")) != NULL) {
+        
+        if (hints->ai_flags | AI_CANONNAME) {
+            printf("WARNING: AI_CANONAME set\n");
+        }
+        return ohreal_getaddrinfo(real, service,
+                                   hints, res);
+    }
+    else {
+        return ohreal_getaddrinfo(node, service,
+                                   hints, res);
+    }
+}

diff --git a/overhosts.h b/overhosts.h
new file mode 100644 (file)
index 0000000..8bf509a
--- /dev/null
+++ b/overhosts.h
@@ -0,0 +1,24 @@
+/* 
+ *  overhosts.h
+ *
+ *  Copyright (C) 2012 
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABLILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details. You should have received a
+ * copy of the GNU General Public License along with this program; if
+ * not, write to the Free Software Foundation, Inc, 59 Temple Place - 
+ * Suite 330, Boston, MA 02111-1307, USA.
+ * 
+ */
+
+
+#include <stdlib.h>
+#include <stdio.h>
+

diff --git a/test.c b/test.c
new file mode 100644 (file)
index 0000000..90715bc
--- /dev/null
+++ b/test.c
@@ -0,0 +1,65 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <netdb.h>
+#include <arpa/inet.h>
+
+#define BUF_SIZE 500
+
+int
+main(int argc, char *argv[])
+{
+    struct addrinfo hints;
+    struct addrinfo *result, *rp;
+    int s;
+
+    if (argc < 3) {
+        fprintf(stderr, "Usage: %s host port msg...\n", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+
+    /* Obtain address(es) matching host/port */
+
+    memset(&hints, 0, sizeof(struct addrinfo));
+    hints.ai_family = 0;    /* Allow IPv4 or IPv6 */
+    hints.ai_socktype = SOCK_STREAM; /* Datagram socket */
+    /* hints.ai_flags = 0; */
+    hints.ai_flags = AI_CANONNAME;    /* For wildcard IP address */
+    hints.ai_protocol = 0;          /* Any protocol */
+    hints.ai_canonname = NULL;
+    hints.ai_addr = NULL;
+    hints.ai_next = NULL;
+
+    s = getaddrinfo(argv[1], argv[2], &hints, &result);
+    if (s != 0) {
+        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(s));
+        exit(EXIT_FAILURE);
+    }
+
+    /* getaddrinfo() returns a list of address structures.
+       Try each address until we successfully connect(2).
+       If socket(2) (or connect(2)) fails, we (close the socket
+       and) try the next address. */
+
+    for (rp = result; rp != NULL; rp = rp->ai_next) {
+        printf("ai_flags:    %d\n", rp->ai_flags);
+        printf("ai_family:   %d\n", rp->ai_family);
+        printf("ai_socktype: %d\n", rp->ai_socktype);
+        printf("ai_protocol: %d\n", rp->ai_protocol);
+        printf("ai_addrlen:  %d\n", rp->ai_addrlen);
+        printf("ai_addr.type: %d\n", rp->ai_addr->sa_family); /* PF_INET */
+        if (rp->ai_addr->sa_family == AF_INET) {
+            printf("sin_port: %d\n" , ntohs(((struct sockaddr_in *)rp->ai_addr)->sin_port));
+            printf("sin_addr: %s\n", inet_ntoa(((struct sockaddr_in *)rp->ai_addr)->sin_addr));
+        }
+        printf("ai_canonname:[%s]\n", rp->ai_canonname);
+    }
+
+    freeaddrinfo(result);           /* No longer needed */
+
+    exit(EXIT_SUCCESS);
+}