dockerip

.gitignore

@@ -2,3 +2,4 @@
 *.o
 /libnss_docker.so.2
 /test
+/dockerip

Makefile

@@ -1,6 +1,9 @@
 DESTDIR ?=
 NSSDIR ?= /usr/lib
+BINDIR ?= /usr/bin
 
+
+STRIP = strip
 CC = gcc
 CFLAGS = -fPIC -Wall -Werror -ggdb `pkg-config --cflags glib-2.0`
 LDFLAGS = `pkg-config --libs glib-2.0`
@@ -12,22 +15,30 @@ MODULE = libnss_docker.so.2
 
 BINS = \
 	$(MODULE) \
-	test
+	test dockerip
 
 $(MODULE): $(OBJS) Makefile
 	$(CC) -fPIC -shared -o $@ -Wl,-soname,$@ $< $(LDFLAGS)
 
 TEST_OBJS = \
 	test.o
 
+INSPECT_OBJS = \
+	dockerip.o
+
 test: $(TEST_OBJS) $(MODULE) Makefile
 	$(CC) -o $@ $< $(LDFLAGS)
 
+dockerip: $(INSPECT_OBJS) $(MODULE) Makefile
+	$(CC) -o $@ $<
+	$(STRIP) $@
+
 all: $(BINS)
 
 install: all
-	mkdir -p $(DESTDIR)$(NSSDIR)
+	mkdir -p $(DESTDIR)$(NSSDIR) $(DESTDIR)$(BINDIR)
 	install -m 0644 $(MODULE) $(DESTDIR)$(NSSDIR)/$(MODULE)
+	install -g docker -m 2755 dockerip $(DESTDIR)$(BINDIR)/dockerip
 	ldconfig
 
 clean:

README.md

@@ -8,7 +8,9 @@ This is still a work in progress!
 Installing
 ==========
 
-    git clone git@github.com:danni/docker-nss.git
+Ensure `make`, `gcc`, and `libglib2.0-dev` are installed on the system.
+
+    git clone git@github.com:weng-lab/docker-nss.git
     cd docker-nss
     sudo make all install
     sudo sed -i -re 's/^(hosts: .*$)/\1 docker/' /etc/nsswitch.conf

dockerip.c

@@ -0,0 +1,14 @@
+#include <unistd.h>
+#include <string.h>
+#include <stdio.h>
+
+int main(int argc, char** argv)
+{
+    // run if one argument was supplied that does not start with '-'
+    if (argc == 2 && strnlen(argv[1], 255) > 2 && argv[1][0] != '-') {
+        const char* myargs[] = { "/usr/bin/docker", "inspect", "--format={{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}", argv[1] };
+        return execlp(myargs[0], myargs[0], myargs[1], myargs[2], myargs[3], NULL);
+    }
+    printf("usage: %s <container>\n", argv[0]);
+    return 1;
+}

nss.c

@@ -29,185 +29,144 @@
 /* define a suffix that containers have */
 #define SUFFIX ".docker"
 
-#define ALIGN(a) (((a+sizeof(void*)-1)/sizeof(void*))*sizeof(void*))
-
-static void
-pack_hostent(struct hostent *result,
-        char *buffer,
-        size_t buflen,
-        const char *name,
-        const void *addr)
+#define ALIGN(a) (((a + sizeof(void*) - 1) / sizeof(void*)) * sizeof(void*))
+
+static void pack_hostent(struct hostent* result, char* buffer, size_t buflen,
+                         const char* name, const void* addr)
 {
-    char *aliases, *r_addr, *addrlist;
+    char* aliases, *r_addr, *addrlist;
     size_t l, idx;
 
     /* we can't allocate any memory, the buffer is where we need to
-     * return things we want to use
-     *
-     * 1st, the hostname */
+ * return things we want to use
+ *
+ * 1st, the hostname */
     l = strlen(name);
     result->h_name = buffer;
-    memcpy (result->h_name, name, l);
+    memcpy(result->h_name, name, l);
     buffer[l] = '\0';
 
-    idx = ALIGN (l+1);
+    idx = ALIGN(l + 1);
 
     /* 2nd, the empty aliases array */
     aliases = buffer + idx;
-    *(char **) aliases = NULL;
-    idx += sizeof (char*);
+    *(char**)aliases = NULL;
+    idx += sizeof(char*);
 
-    result->h_aliases = (char **) aliases;
+    result->h_aliases = (char**)aliases;
 
     result->h_addrtype = AF_INET;
-    result->h_length = sizeof (struct in_addr);
+    result->h_length = sizeof(struct in_addr);
 
     /* 3rd, address */
     r_addr = buffer + idx;
     memcpy(r_addr, addr, result->h_length);
-    idx += ALIGN (result->h_length);
+    idx += ALIGN(result->h_length);
 
     /* 4th, the addresses ptr array */
     addrlist = buffer + idx;
-    ((char **) addrlist)[0] = r_addr;
-    ((char **) addrlist)[1] = NULL;
+    ((char**)addrlist)[0] = r_addr;
+    ((char**)addrlist)[1] = NULL;
 
-    result->h_addr_list = (char **) addrlist;
+    result->h_addr_list = (char**)addrlist;
 }
 
-static gboolean
-lookup_container_ip (const char *name,
-        struct in_addr *addr)
+static gboolean lookup_container_ip(const char* name, struct in_addr* addr)
 {
-    char *stdout_s, *name_s;
+    char* stdout_s, *name_s;
     int exit_status;
     gboolean success = FALSE;
 
     /* remove the suffix */
-    name_s = g_strdup (name);
+    name_s = g_strdup(name);
     *strrchr(name_s, '.') = '\0';
 
-    char *argv[] = {
-        "docker",
-        "inspect",
-        "-format={{.NetworkSettings.IPAddress}}",
-        name_s,
-        NULL,
-    };
-
-    if (!g_spawn_sync(NULL,
-               argv,
-               NULL,
-               G_SPAWN_STDERR_TO_DEV_NULL | G_SPAWN_SEARCH_PATH,
-               NULL, NULL,
-               &stdout_s, NULL,
-               &exit_status,
-               NULL))
-      {
-          goto finally;
-      }
-
-    if (exit_status != 0)
-      {
+    char* argv[] = { "/usr/bin/dockerip", name_s, NULL, };
+
+    if (!g_spawn_sync(NULL, argv, NULL,
+                      G_SPAWN_STDERR_TO_DEV_NULL | G_SPAWN_SEARCH_PATH, NULL,
+                      NULL, &stdout_s, NULL, &exit_status, NULL)) {
         goto finally;
-      }
+    }
 
-    stdout_s = g_strstrip (stdout_s);
-    success = inet_aton (stdout_s, addr);
+    if (exit_status != 0) {
+        goto finally;
+    }
+
+    stdout_s = g_strstrip(stdout_s);
+    success = inet_aton(stdout_s, addr);
 
 finally:
 
-    g_free (name_s);
-    g_free (stdout_s);
+    g_free(name_s);
+    g_free(stdout_s);
 
     return success;
 }
 
-enum nss_status
-_nss_docker_gethostbyname2_r (const char *name,
-        int af,
-        struct hostent *result,
-        char *buffer,
-        size_t buflen,
-        int *errnop,
-        int *h_errnop)
+enum nss_status _nss_docker_gethostbyname2_r(const char* name, int af,
+                                             struct hostent* result,
+                                             char* buffer, size_t buflen,
+                                             int* errnop, int* h_errnop)
 {
     struct in_addr addr;
 
-    if (af != AF_INET)
-      {
+    if (af != AF_INET) {
         *errnop = EAFNOSUPPORT;
         *h_errnop = NO_DATA;
         return NSS_STATUS_UNAVAIL;
-      }
+    }
 
-    if (!g_str_has_suffix(name, SUFFIX))
-      {
+    if (!g_str_has_suffix(name, SUFFIX)) {
         *errnop = ENOENT;
         *h_errnop = HOST_NOT_FOUND;
         return NSS_STATUS_NOTFOUND;
-      }
+    }
 
-    if (!lookup_container_ip (name, &addr))
-      {
+    if (!lookup_container_ip(name, &addr)) {
         *errnop = ENOENT;
         *h_errnop = HOST_NOT_FOUND;
         return NSS_STATUS_NOTFOUND;
-      }
+    }
 
     pack_hostent(result, buffer, buflen, name, &addr);
 
     return NSS_STATUS_SUCCESS;
 }
 
-enum nss_status
-_nss_docker_gethostbyname_r (const char *name,
-        struct hostent *result,
-        char *buffer,
-        size_t buflen,
-        int *errnop,
-        int *h_errnop)
+enum nss_status _nss_docker_gethostbyname_r(const char* name,
+                                            struct hostent* result,
+                                            char* buffer, size_t buflen,
+                                            int* errnop, int* h_errnop)
 {
-    return _nss_docker_gethostbyname2_r(name,
-            AF_INET,
-            result,
-            buffer,
-            buflen,
-            errnop,
-            h_errnop);
+    return _nss_docker_gethostbyname2_r(name, AF_INET, result, buffer, buflen,
+                                        errnop, h_errnop);
 }
 
-enum nss_status
-_nss_docker_gethostbyaddr_r (const void *addr,
-        socklen_t len,
-        int af,
-        struct hostent *result,
-        char *buffer,
-        size_t buflen,
-        int *errnop,
-        int *h_errnop)
+enum nss_status _nss_docker_gethostbyaddr_r(const void* addr, socklen_t len,
+                                            int af, struct hostent* result,
+                                            char* buffer, size_t buflen,
+                                            int* errnop, int* h_errnop)
 {
-    if (af != AF_INET)
-      {
+    if (af != AF_INET) {
         *errnop = EAFNOSUPPORT;
         *h_errnop = NO_DATA;
         return NSS_STATUS_UNAVAIL;
-      }
+    }
 
-    if (len != sizeof (struct in_addr))
-      {
+    if (len != sizeof(struct in_addr)) {
         *errnop = EINVAL;
         *h_errnop = NO_RECOVERY;
         return NSS_STATUS_UNAVAIL;
-      }
+    }
 
     /* FIXME: need to implement reverse lookups */
     *errnop = EAFNOSUPPORT;
     *h_errnop = NO_DATA;
     return NSS_STATUS_UNAVAIL;
     /*
-    pack_hostent(result, buffer, buflen, "container.docker", addr);
+pack_hostent(result, buffer, buflen, "container.docker", addr);
 
-    return NSS_STATUS_SUCCESS;
-    */
+return NSS_STATUS_SUCCESS;
+*/
 }