libaar initial commit

git-svn-id: file:///home/lennart/svn/public/libasyncns/trunk@3 cc0fb855-19ed-0310-866e-8c1d96e4abae

4 files changed, 983 insertions, 0 deletions

diff --git a/libaar/Makefile b/libaar/Makefile
new file mode 100644
index 0000000..b2f6aef
--- /dev/null
+++ b/libaar/Makefile
@@ -0,0 +1,8 @@
+CFLAGS=-Wall -W -O0 -g -pipe
+
+
+aar-test: aar.o aar-test.o
+	$(CC) -o $@ $^ $(LIBS) $(CFLAGS)
+
+clean:
+	rm -rf *.o aar-test
diff --git a/libaar/aar-test.c b/libaar/aar-test.c
new file mode 100644
index 0000000..da8e76a
--- /dev/null
+++ b/libaar/aar-test.c
@@ -0,0 +1,79 @@
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+#include <stdio.h>
+
+#include "aar.h"
+
+int main(int argc, char *argv[]) {
+    aar_t* aar = NULL;
+    aar_query_t *q1, *q2;
+    int r = 1, ret;
+    struct addrinfo *ai, hints;
+    struct sockaddr_in sa;
+    char host[NI_MAXHOST] = "", serv[NI_MAXSERV] = "";
+
+    memset(&hints, 0, sizeof(hints));
+    hints.ai_family = PF_UNSPEC;
+    hints.ai_socktype = SOCK_STREAM;
+
+    if (!(aar = aar_new(5))) {
+        fprintf(stderr, "aar_new() failed\n");
+        goto fail;
+    }
+
+
+    memset(&sa, 0, sizeof(sa));
+    sa.sin_family = AF_INET;
+    sa.sin_addr.s_addr = inet_addr("192.168.50.1");
+    sa.sin_port = htons(80);
+    
+    q1 = aar_getaddrinfo(aar, argc >= 2 ? argv[1] : "www.heise.de", NULL, &hints);
+    q2 = aar_getnameinfo(aar, (struct sockaddr*) &sa, sizeof(sa), 0, 1, 1); 
+
+    while (!aar_isdone(aar, q1) || !aar_isdone(aar, q2)) {
+        if (aar_wait(aar, 1) < 0)
+            goto fail;
+    }
+
+    ret = aar_getaddrinfo_done(aar, q1, &ai);
+
+    if (ret)
+        fprintf(stderr, "error: %s %i\n", gai_strerror(ret), ret);
+    else {
+        struct addrinfo *i;
+
+        for (i = ai; i; i = i->ai_next) {
+            char t[256];
+            const char *p = NULL;
+
+            if (i->ai_family == PF_INET) 
+                p = inet_ntop(AF_INET, &((struct sockaddr_in*) i->ai_addr)->sin_addr, t, sizeof(t));
+            else if (i->ai_family == PF_INET6)
+                p = inet_ntop(AF_INET6, &((struct sockaddr_in6*) i->ai_addr)->sin6_addr, t, sizeof(t));
+                          
+            printf("%s\n", p);
+        }
+
+        aar_freeaddrinfo(ai);
+    }
+
+    ret = aar_getnameinfo_done(aar, q2, host, sizeof(host), serv, sizeof(serv));
+
+    if (ret)
+        fprintf(stderr, "error: %s %i\n", gai_strerror(ret), ret);
+    else {
+        printf("%s -- %s\n", host, serv);
+    }
+    
+    
+    r = 0;
+
+fail:
+
+    if (aar)
+        aar_free(aar);
+    
+    return r;
+}
diff --git a/libaar/aar.c b/libaar/aar.c
new file mode 100644
index 0000000..1cd6b9d
--- /dev/null
+++ b/libaar/aar.c
@@ -0,0 +1,860 @@
+#define _GNU_SOURCE
+#define HAVE_PR_SET_PDEATHSIG
+#define HAVE_SETRESUID
+
+#include <assert.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <unistd.h>
+#include <sys/select.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <sys/wait.h>
+#include <sys/types.h>
+#include <pwd.h>
+
+#ifdef HAVE_PR_SET_PDEATHSIG
+#include <sys/prctl.h>
+#endif
+
+#include "aar.h"
+
+#define MAX_WORKERS 16
+#define MAX_QUERIES 256
+#define BUFSIZE (10240)
+
+typedef enum {
+    REQUEST_ADDRINFO,
+    RESPONSE_ADDRINFO,
+    REQUEST_NAMEINFO,
+    RESPONSE_NAMEINFO
+} query_type_t;
+
+struct aar {
+    int in_fd, out_fd;
+
+    pid_t workers[MAX_WORKERS];
+
+    unsigned current_id, current_index;
+    aar_query_t* queries[MAX_QUERIES];
+
+    aar_query_t *done_head, *done_tail;
+
+    int n_queries;
+};
+
+struct aar_query {
+    aar_t *aar;
+    int done;
+    unsigned id;
+    query_type_t type;
+    aar_query_t *done_next, *done_prev;
+    int ret;
+    struct addrinfo *addrinfo;
+    char *serv, *host;
+    void *userdata;
+};
+
+typedef struct rheader {
+    query_type_t type;
+    unsigned id;
+    size_t length;
+} rheader_t;
+
+typedef struct addrinfo_request {
+    struct rheader header;
+    int hints_is_null;
+    int ai_flags;
+    int ai_family;
+    int ai_socktype;
+    int ai_protocol;
+    size_t node_len, service_len;
+} addrinfo_request_t;
+
+typedef struct addrinfo_response {
+    struct rheader header;
+    int ret;
+} addrinfo_response_t;
+
+typedef struct addrinfo_serialization {
+    int ai_flags;
+    int ai_family;
+    int ai_socktype;
+    int ai_protocol;
+    size_t ai_addrlen;
+    size_t canonname_len;
+} addrinfo_serialization_t;
+
+typedef struct nameinfo_request {
+    struct rheader header;
+    int flags;
+    socklen_t sockaddr_len;
+    int gethost, getserv;
+} nameinfo_request_t;
+
+typedef struct nameinfo_response {
+    struct rheader header;
+    size_t hostlen, servlen;
+    int ret;
+} nameinfo_response_t;
+
+static int fd_nonblock(int fd) {
+    int i;
+    assert(fd >= 0);
+
+    if ((i = fcntl(fd, F_GETFL)) < 0)
+        return -1;
+
+    if (i & O_NONBLOCK)
+        return 0;
+
+    return fcntl(fd, F_SETFL, i | O_NONBLOCK);
+}
+
+static void *serialize_addrinfo(void *p, const struct addrinfo *ai, size_t *length, size_t maxlength) {
+    addrinfo_serialization_t *s = p;
+    size_t cnl, l;
+    assert(p);
+    assert(ai);
+    assert(length);
+    assert(*length <= maxlength);
+
+    cnl = (ai->ai_canonname ? strlen(ai->ai_canonname)+1 : 0);
+    l = sizeof(addrinfo_serialization_t) + ai->ai_addrlen + cnl;
+
+    if (*length + l > maxlength)
+        return NULL;
+
+    s->ai_flags = ai->ai_flags;
+    s->ai_family = ai->ai_family;
+    s->ai_socktype = ai->ai_socktype;
+    s->ai_protocol = ai->ai_protocol;
+    s->ai_addrlen = ai->ai_addrlen;
+    s->canonname_len = cnl;
+
+    memcpy((uint8_t*) p + sizeof(addrinfo_serialization_t), ai->ai_addr, ai->ai_addrlen);
+
+    if (ai->ai_canonname)
+        strcpy((char*) p + sizeof(addrinfo_serialization_t) + ai->ai_addrlen, ai->ai_canonname);
+
+    *length += l;
+    return (uint8_t*) p + l;
+}
+
+static int send_addrinfo_reply(int out_fd, unsigned id, int ret, struct addrinfo *ai) {
+    assert(out_fd >= 0);
+    uint8_t data[BUFSIZE];
+    addrinfo_response_t *resp = (addrinfo_response_t*) data;
+
+    resp->header.type = RESPONSE_ADDRINFO;
+    resp->header.id = id;
+    resp->header.length = sizeof(addrinfo_response_t);
+    resp->ret = ret;
+
+    if (ret == 0 && ai) {
+        void *p = data + sizeof(addrinfo_response_t);
+
+        while (ai && p) {
+            p = serialize_addrinfo(p, ai, &resp->header.length, BUFSIZE);
+            ai = ai->ai_next;
+        }
+    }
+
+    return send(out_fd, resp, resp->header.length, 0);
+}
+
+static int send_nameinfo_reply(int out_fd, unsigned id, int ret, const char *host, const char *serv) {
+    assert(out_fd >= 0);
+    uint8_t data[BUFSIZE];
+    size_t hl, sl;
+    nameinfo_response_t *resp = (nameinfo_response_t*) data;
+
+    sl = serv ? strlen(serv)+1 : 0;
+    hl = host ? strlen(host)+1 : 0;
+
+    resp->header.type = RESPONSE_NAMEINFO;
+    resp->header.id = id;
+    resp->header.length = sizeof(nameinfo_response_t) + hl + sl;
+    resp->ret = ret;
+    resp->hostlen = hl;
+    resp->servlen = sl;
+
+    assert(sizeof(data) >= resp->header.length);
+    
+    if (host)
+        memcpy(data + sizeof(nameinfo_response_t), host, hl);
+
+    if (serv)
+        memcpy(data + sizeof(nameinfo_response_t) + hl, serv, sl);
+    
+    return send(out_fd, resp, resp->header.length, 0);
+}
+
+static int handle_request(int out_fd, const rheader_t *req, size_t length) {
+    assert(out_fd >= 0);
+    assert(req);
+    assert(length >= sizeof(rheader_t));
+    assert(length == req->length);
+
+    switch (req->type) {
+        case REQUEST_ADDRINFO: {
+            struct addrinfo ai, *result = NULL;
+            const addrinfo_request_t *ai_req = (addrinfo_request_t*) req;
+            const char *node, *service;
+            int ret;
+
+            assert(length >= sizeof(addrinfo_request_t));
+            assert(length == sizeof(addrinfo_request_t) + ai_req->node_len + ai_req->service_len);
+
+            memset(&ai, 0, sizeof(ai));
+            ai.ai_flags = ai_req->ai_flags;
+            ai.ai_family = ai_req->ai_family;
+            ai.ai_socktype = ai_req->ai_socktype;
+            ai.ai_protocol = ai_req->ai_protocol;
+
+            node = ai_req->node_len ? (const char*) req + sizeof(addrinfo_request_t) : NULL;
+            service = ai_req->service_len ? (const char*) req + sizeof(addrinfo_request_t) + ai_req->node_len : NULL;
+
+            ret = getaddrinfo(node, service,
+                              ai_req->hints_is_null ? NULL : &ai,
+                              &result);
+            ret = send_addrinfo_reply(out_fd, req->id, ret, result);
+
+            if (result)
+                freeaddrinfo(result);
+
+            return ret;
+        }
+
+        case REQUEST_NAMEINFO: {
+            int ret;
+            const nameinfo_request_t *ni_req = (nameinfo_request_t*) req;
+            char hostbuf[NI_MAXHOST], servbuf[NI_MAXSERV];
+            const struct sockaddr *sa;
+            
+            assert(length >= sizeof(nameinfo_request_t));
+            assert(length == sizeof(nameinfo_request_t) + ni_req->sockaddr_len);
+
+            sa = (const struct sockaddr*) ((const char*) req + sizeof(nameinfo_request_t));
+            
+            ret = getnameinfo(sa, ni_req->sockaddr_len,
+                              ni_req->gethost ? hostbuf : NULL, ni_req->gethost ? sizeof(hostbuf) : 0,
+                              ni_req->getserv ? servbuf : NULL, ni_req->getserv ? sizeof(servbuf) : 0,
+                              ni_req->flags);
+
+            return send_nameinfo_reply(out_fd, req->id, ret,
+                                       ret == 0 && ni_req->gethost ? hostbuf : NULL,
+                                       ret == 0 && ni_req->getserv ? servbuf : NULL);
+        }
+
+        default:
+            ;
+    }
+
+    return 0;
+}
+
+static int worker(int in_fd, int out_fd) {
+    int r = 0;
+    assert(in_fd > 2);
+    assert(out_fd > 2);
+    
+    close(0);
+    close(1);
+    close(2);
+
+    open("/dev/null", O_RDONLY);
+    open("/dev/null", O_WRONLY);
+    open("/dev/null", O_WRONLY);
+
+    chdir("/");
+
+    if (geteuid() == 0) {
+        struct passwd *pw;
+
+        if ((pw = getpwnam("nobody"))) {
+#ifdef HAVE_SETRESUID            
+            setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid);
+#elif HAVE_SETREUID
+            setuid(pw->pw_uid, pw->pw_uid);
+#else
+            setuid(pw->pw_uid);
+            seteuid(pw->pw_uid);
+#endif
+        }
+    }
+
+    signal(SIGTERM, SIG_DFL);
+
+    signal(SIGINT, SIG_IGN);
+    signal(SIGHUP, SIG_IGN);
+    signal(SIGPIPE, SIG_IGN);
+    signal(SIGUSR1, SIG_IGN);
+    signal(SIGUSR2, SIG_IGN);
+
+#ifdef HAVE_PR_SET_PDEATHSIG
+    prctl(PR_SET_PDEATHSIG, SIGTERM);
+#else
+    fd_nonblock(in_fd);
+#endif
+    
+    while (getppid() != 1) { /* if the parent PID is 1 our parent process died. */
+        char buf[BUFSIZE];
+        ssize_t length;
+
+#ifndef HAVE_PR_SET_PDEATHSIG
+        fd_set fds;
+        struct timeval tv = { 0, 500000 } ;
+
+        FD_ZERO(&fds);
+        FD_SET(in_fd, &fds);
+
+        if (select(in_fd+1, &fds, NULL, NULL, &tv) < 0)
+            goto fail;
+
+        if (getppid() == 1)
+            break;
+#endif
+        
+        if ((length = recv(in_fd, buf, sizeof(buf), 0)) <= 0) {
+
+            if (length < 0 && errno == EAGAIN)
+                continue;
+            
+            goto fail;
+        }
+
+        if (handle_request(out_fd, (rheader_t*) buf, (size_t) length) < 0)
+            goto fail;
+    }
+
+fail:
+
+    close(in_fd);
+    close(out_fd);
+    
+    return r;
+}
+
+aar_t* aar_new(int n_proc) {
+    aar_t *aar = NULL;
+    int fd1[2] = { -1, -1 }, fd2[2] = { -1, -1 }, p;
+
+    assert(n_proc >= 1);
+
+    if (!(aar = malloc(sizeof(aar_t))))
+        goto fail;
+
+    aar->in_fd = aar->out_fd = -1;
+    memset(aar->workers, 0, sizeof(aar->workers));
+    
+    if (socketpair(PF_UNIX, SOCK_DGRAM, 0, fd1) < 0)
+        goto fail;
+
+    if (socketpair(PF_UNIX, SOCK_DGRAM, 0, fd2) < 0)
+        goto fail;
+
+    if (n_proc > MAX_WORKERS)
+        n_proc = MAX_WORKERS;
+
+    for (p = 0; p < n_proc; p++) {
+
+        if ((aar->workers[p] = fork()) < 0)
+            goto fail;
+        else if (aar->workers[p] == 0) {
+            close(fd1[0]);
+            close(fd2[1]);
+            _exit(worker(fd2[0], fd1[1]));
+        }
+    }
+
+    close(fd2[0]);
+    close(fd1[1]);
+    aar->in_fd = fd1[0];
+    aar->out_fd = fd2[1];
+
+    aar->current_index = aar->current_id = 0;
+
+    for (p = 0; p < MAX_QUERIES; p++)
+        aar->queries[p] = NULL;
+/*     memset(aar->queries, 0, sizeof(aar->queries)); */
+
+    aar->done_head = aar->done_tail = NULL;
+    aar->n_queries = 0;
+
+    fd_nonblock(aar->in_fd);
+
+    return aar;
+
+fail:
+
+    if (fd1[0] >= 0) close(fd1[0]);
+    if (fd1[1] >= 0) close(fd1[1]);
+    if (fd2[0] >= 0) close(fd2[0]);
+    if (fd2[1] >= 0) close(fd2[1]);
+
+    if (aar) 
+        aar_free(aar);
+
+    return NULL;
+}
+
+void aar_free(aar_t *aar) {
+    int p;
+    assert(aar);
+    
+    if (aar->in_fd >= 0)
+        close(aar->in_fd);
+    if (aar->out_fd >= 0)
+        close(aar->out_fd);
+    
+    for (p = 0; p < MAX_WORKERS; p++)
+        if (aar->workers[p] >= 1) {
+            kill(aar->workers[p], SIGTERM);
+            waitpid(aar->workers[p], NULL, 0);
+        }
+
+    for (p = 0; p < MAX_QUERIES; p++)
+        if (aar->queries[p])
+            aar_cancel(aar, aar->queries[p]);
+    
+    free(aar);
+}
+
+int aar_fd(aar_t *aar) {
+    assert(aar);
+
+    return aar->in_fd;
+}
+
+static aar_query_t *lookup_query(aar_t *aar, unsigned id) {
+    aar_query_t *q;
+    assert(aar);
+
+    if ((q = aar->queries[id % MAX_QUERIES]))
+        if (q->id == id)
+            return q;
+
+    return NULL;
+}
+
+static void complete_query(aar_t *aar, aar_query_t *q) {
+    assert(aar);
+    assert(q);
+    assert(!q->done);
+
+    q->done = 1;
+    
+    if ((q->done_prev = aar->done_tail))
+        aar->done_tail->done_next = q;
+    else
+        aar->done_head = q;
+
+    aar->done_tail = q;
+    q->done_next = NULL;
+}
+
+static void *unserialize_addrinfo(void *p, struct addrinfo **ret_ai, size_t *length) {
+    addrinfo_serialization_t *s = p;
+    size_t l;
+    struct addrinfo *ai;
+    assert(p);
+    assert(ret_ai);
+    assert(index);
+
+    if (*length < sizeof(addrinfo_serialization_t))
+        return NULL;
+
+    l = sizeof(addrinfo_serialization_t) + s->ai_addrlen + s->canonname_len;
+    if (*length < l)
+        return NULL;
+
+    if (!(ai = malloc(sizeof(struct addrinfo))))
+        goto fail;
+    
+    ai->ai_addr = NULL;
+    ai->ai_canonname = NULL;
+    ai->ai_next = NULL;
+
+    if (s->ai_addrlen && !(ai->ai_addr = malloc(s->ai_addrlen)))
+        goto fail;
+    
+    if (s->canonname_len && !(ai->ai_canonname = malloc(s->canonname_len)))
+        goto fail;
+
+    ai->ai_flags = s->ai_flags;
+    ai->ai_family = s->ai_family;
+    ai->ai_socktype = s->ai_socktype;
+    ai->ai_protocol = s->ai_protocol;
+    ai->ai_addrlen = s->ai_addrlen;
+
+    if (ai->ai_addr)
+        memcpy(ai->ai_addr, (uint8_t*) p + sizeof(addrinfo_serialization_t), s->ai_addrlen);
+
+    if (ai->ai_canonname)
+        memcpy(ai->ai_canonname, (uint8_t*) p + sizeof(addrinfo_serialization_t) + s->ai_addrlen, s->canonname_len);
+
+    *length -= l;
+    *ret_ai = ai;
+    
+    return (uint8_t*) p + l;
+
+
+fail:
+    if (ai)
+        aar_freeaddrinfo(ai);
+
+    return NULL;
+}
+
+static int handle_response(aar_t *aar, rheader_t *resp, size_t length) {
+    aar_query_t *q;
+    assert(aar);
+    assert(resp);
+    assert(length >= sizeof(rheader_t));
+    assert(length == resp->length);
+
+    if (!(q = lookup_query(aar, resp->id)))
+        return 0;
+    
+    switch (resp->type) {
+        case RESPONSE_ADDRINFO: {
+            const addrinfo_response_t *ai_resp = (addrinfo_response_t*) resp;
+            void *p;
+            size_t l;
+            struct addrinfo *prev = NULL;
+
+            assert(length >= sizeof(addrinfo_response_t));
+            assert(q->type == REQUEST_ADDRINFO);
+
+            q->ret = ai_resp->ret;
+            l = length - sizeof(addrinfo_response_t);
+            p = (uint8_t*) resp + sizeof(addrinfo_response_t);
+
+            while (l > 0 && p) {
+                struct addrinfo *ai = NULL;
+                p = unserialize_addrinfo(p, &ai, &l);
+
+                if (!ai)
+                    break;
+
+                if (prev)
+                    prev->ai_next = ai;
+                else
+                    q->addrinfo = ai;
+
+                prev = ai;
+            }
+
+            complete_query(aar, q);
+            break;
+        }
+
+        case RESPONSE_NAMEINFO: {
+            const nameinfo_response_t *ni_resp = (nameinfo_response_t*) resp;
+
+            assert(length >= sizeof(nameinfo_response_t));
+            assert(q->type = REQUEST_NAMEINFO);
+
+            q->ret = ni_resp->ret;
+
+            if (ni_resp->hostlen)
+                q->host = strndup((char*) ni_resp + sizeof(nameinfo_response_t), ni_resp->hostlen-1);
+
+            if (ni_resp->servlen)
+                q->serv = strndup((char*) ni_resp + sizeof(nameinfo_response_t) + ni_resp->hostlen, ni_resp->servlen-1);
+                    
+
+            complete_query(aar, q);
+            break;
+        }
+            
+        default:
+            ;
+    }
+    
+    return 0;
+}
+
+int aar_wait(aar_t *aar, int block) {
+    assert(aar);
+
+    for (;;) {
+        char buf[BUFSIZE];
+        ssize_t l;
+
+        if (((l = recv(aar->in_fd, buf, sizeof(buf), 0)) < 0)) {
+            fd_set fds;
+
+            if (errno != EAGAIN)
+                return -1;
+
+            if (!block)
+                return 0;
+                
+            FD_ZERO(&fds);
+            FD_SET(aar->in_fd, &fds);
+
+            if (select(aar->in_fd+1, &fds, NULL, NULL, NULL) < 0)
+                return -1;
+                
+            continue;
+        }
+
+
+        return handle_response(aar, (rheader_t*) buf, (size_t) l);
+    }
+}
+
+static aar_query_t *alloc_query(aar_t *aar) {
+    aar_query_t *q;
+    assert(aar);
+
+    if (aar->n_queries >= MAX_QUERIES)
+        return NULL;
+
+    while (aar->queries[aar->current_index]) {
+
+        aar->current_index++;
+        aar->current_id++;
+
+        while (aar->current_index >= MAX_QUERIES)
+            aar->current_index -= MAX_QUERIES;
+    }
+        
+    if (!(q = aar->queries[aar->current_index] = malloc(sizeof(aar_query_t))))
+        return NULL;
+
+    aar->n_queries++;
+
+    q->aar = aar;
+    q->done = 0;
+    q->id = aar->current_id;
+    q->done_next = q->done_prev = NULL;
+    q->ret = 0;
+    q->addrinfo = NULL;
+    q->userdata = NULL;
+    q->host = q->serv = NULL;
+
+    return q;
+}
+
+aar_query_t* aar_getaddrinfo(aar_t *aar, const char *node, const char *service, const struct addrinfo *hints) {
+    uint8_t data[BUFSIZE];
+    addrinfo_request_t *req = (addrinfo_request_t*) data;
+    aar_query_t *q;
+    assert(aar);
+    assert(node || service);
+
+    if (!(q = alloc_query(aar)))
+        return NULL;
+
+    memset(req, 0, sizeof(addrinfo_request_t));
+    
+    req->node_len = node ? strlen(node)+1 : 0;
+    req->service_len = service ? strlen(service)+1 : 0;
+    
+    req->header.id = q->id;
+    req->header.type = q->type = REQUEST_ADDRINFO;
+    req->header.length = sizeof(addrinfo_request_t) + req->node_len + req->service_len;
+
+    if (req->header.length > BUFSIZE)
+        goto fail;
+
+    if (!(req->hints_is_null = !hints)) {
+        req->ai_flags = hints->ai_flags; 
+        req->ai_family = hints->ai_family;
+        req->ai_socktype = hints->ai_socktype;
+        req->ai_protocol = hints->ai_protocol;
+    }
+
+    if (node)
+        strcpy((char*) req + sizeof(addrinfo_request_t), node);
+
+    if (service)
+        strcpy((char*) req + sizeof(addrinfo_request_t) + req->node_len, service);
+
+    if (send(aar->out_fd, req, req->header.length, 0) < 0)
+        goto fail;
+    
+    return q;
+
+fail:
+    if (q)
+        aar_cancel(aar, q);
+
+    return NULL;
+}
+
+int aar_getaddrinfo_done(aar_t *aar, aar_query_t* q, struct addrinfo **ret_res) {
+    int ret;
+    assert(aar);
+    assert(q);
+    assert(q->aar == aar);
+    assert(q->type == REQUEST_ADDRINFO);
+
+    if (!q->done)
+        return EAI_AGAIN;
+
+    *ret_res = q->addrinfo;
+    q->addrinfo = NULL;
+    ret = q->ret;
+    aar_cancel(aar, q);
+
+    return ret;
+}
+
+aar_query_t* aar_getnameinfo(aar_t *aar, const struct sockaddr *sa, socklen_t salen, int flags, int gethost, int getserv) {
+    uint8_t data[BUFSIZE];
+    nameinfo_request_t *req = (nameinfo_request_t*) data;
+    aar_query_t *q;
+
+    assert(aar);
+    assert(sa);
+    assert(salen > 0);
+
+    if (!(q = alloc_query(aar)))
+        return NULL;
+
+    memset(req, 0, sizeof(nameinfo_request_t));
+    
+    req->header.id = q->id;
+    req->header.type = q->type = REQUEST_NAMEINFO;
+    req->header.length = sizeof(nameinfo_request_t) + salen;
+
+    if (req->header.length > BUFSIZE)
+        goto fail;
+
+    req->flags = flags;
+    req->sockaddr_len = salen;
+    req->gethost = gethost;
+    req->getserv = getserv;
+
+    memcpy((uint8_t*) req + sizeof(nameinfo_request_t), sa, salen);
+
+    if (send(aar->out_fd, req, req->header.length, 0) < 0)
+        goto fail;
+    
+    return q;
+
+fail:
+    if (q)
+        aar_cancel(aar, q);
+
+    return NULL;
+}
+
+int aar_getnameinfo_done(aar_t *aar, aar_query_t* q, char *ret_host, size_t hostlen, char *ret_serv, size_t servlen) {
+    int ret;
+    assert(aar);
+    assert(q);
+    assert(q->aar == aar);
+    assert(q->type == REQUEST_NAMEINFO);
+    assert(!ret_host || hostlen);
+    assert(!ret_serv || servlen);
+
+    if (!q->done)
+        return EAI_AGAIN;
+
+    if (ret_host && q->host) {
+        strncpy(ret_host, q->host, hostlen);
+        ret_host[hostlen-1] = 0;
+    }
+
+    if (ret_serv && q->serv) {
+        strncpy(ret_serv, q->serv, servlen);
+        ret_serv[servlen-1] = 0;
+    }
+    
+    ret = q->ret;
+    aar_cancel(aar, q);
+
+    return ret;
+}
+
+aar_query_t* aar_getnext(aar_t *aar) {
+    assert(aar);
+    return aar->done_head;
+}
+
+int aar_getnqueries(aar_t *aar) {
+    assert(aar);
+    return aar->n_queries;
+}
+
+void aar_cancel(aar_t *aar, aar_query_t* q) {
+    int i;
+    assert(aar);
+    assert(q);
+    assert(q->aar == aar);
+    assert(aar->n_queries > 0);
+
+    if (q->done) {
+
+        if (q->done_prev)
+            q->done_prev->done_next = q->done_next;
+        else 
+            aar->done_head = q->done_next;
+
+        if (q->done_next)
+            q->done_next->done_prev = q->done_prev;
+        else
+            aar->done_tail = q->done_prev;
+    }
+
+
+    i = q->id % MAX_QUERIES;
+    assert(aar->queries[i] == q);
+    aar->queries[i] = NULL;
+
+    aar_freeaddrinfo(q->addrinfo);
+    free(q->addrinfo);
+    free(q->host);
+    free(q->serv);
+
+    aar->n_queries--;
+    free(q);
+}
+
+void aar_freeaddrinfo(struct addrinfo *ai) {
+    if (!ai)
+        return;
+
+    while (ai) {
+        struct addrinfo *next = ai->ai_next;
+
+        free(ai->ai_addr);
+        free(ai->ai_canonname);
+        free(ai);
+
+        ai = next;
+    }
+}
+
+int aar_isdone(aar_t *aar, aar_query_t*q) {
+    assert(aar);
+    assert(q);
+    assert(q->aar == aar);
+
+    return q->done;
+}
+
+void aar_setuserdata(aar_t *aar, aar_query_t *q, void *userdata) {
+    assert(q);
+    assert(aar);
+    assert(q->aar = aar);
+    
+    q->userdata = userdata;
+}
+
+void* aar_getuserdata(aar_t *aar, aar_query_t *q) {
+    assert(q);
+    assert(aar);
+    assert(q->aar = aar);
+
+    return q->userdata;
+}
+
+
diff --git a/libaar/aar.h b/libaar/aar.h
new file mode 100644
index 0000000..92b5358
--- /dev/null
+++ b/libaar/aar.h
@@ -0,0 +1,36 @@
+#ifndef fooaarhfoo
+#define fooaarhfoo
+
+#include <sys/socket.h>
+#include <netdb.h>
+
+struct aar;
+typedef struct aar aar_t;
+
+struct aar_query;
+typedef struct aar_query aar_query_t;
+
+aar_t* aar_new(int n_proc);
+void aar_free(aar_t *aar);
+int aar_fd(aar_t *aar);
+int aar_wait(aar_t *aar, int block);
+
+aar_query_t* aar_getaddrinfo(aar_t *aar, const char *node, const char *service, const struct addrinfo *hints);
+int aar_getaddrinfo_done(aar_t *aar, aar_query_t* q, struct addrinfo **ret_res);
+
+aar_query_t* aar_getnameinfo(aar_t *aar, const struct sockaddr *sa, socklen_t salen, int flags, int gethost, int getserv);
+int aar_getnameinfo_done(aar_t *aar, aar_query_t* q, char *ret_host, size_t hostlen, char *ret_serv, size_t servlen);
+
+aar_query_t* aar_getnext(aar_t *aar);
+int aar_getnqueries(aar_t *aar);
+
+void aar_cancel(aar_t *aar, aar_query_t* q);
+
+void aar_freeaddrinfo(struct addrinfo *ai);
+
+int aar_isdone(aar_t *aar, aar_query_t*q);
+
+void aar_setuserdata(aar_t *aar, aar_query_t *q, void *userdata);
+void* aar_getuserdata(aar_t *aar, aar_query_t *q);
+
+#endif