X-Git-Url: http://git.meshlink.io/?a=blobdiff_plain;ds=sidebyside;f=dns.c;h=d518a305690dac40adf4eb14ae4b0ce872e1e179;hb=4c8155fa9c85c7ece92182d0ab53f99a982a4abf;hp=1ac7e6a114d47b01218f2503c35d967e8c3d433c;hpb=4ba1a4b0b4488e5058af67b789187735b529075e;p=catta

diff --git a/dns.c b/dns.c
index 1ac7e6a..d518a30 100644
--- a/dns.c
+++ b/dns.c
@@ -1,111 +1,240 @@
+#include <netinet/in.h>
+
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
 
 #include "dns.h"
+#include "util.h"
+
+flxDnsPacket* flx_dns_packet_new(guint max_size) {
+    flxDnsPacket *p;
+
+    if (max_size <= 0)
+        max_size = FLX_DNS_PACKET_MAX_SIZE;
+    else if (max_size < FLX_DNS_PACKET_HEADER_SIZE)
+        max_size = FLX_DNS_PACKET_HEADER_SIZE;
+    
+    p = g_malloc(sizeof(flxDnsPacket) + max_size);
+    p->size = p->rindex = FLX_DNS_PACKET_HEADER_SIZE;
+    p->max_size = max_size;
+    p->name_table = NULL;
+
+    memset(FLX_DNS_PACKET_DATA(p), 0, p->size);
+    return p;
+}
 
-flxDnsPacket* flx_dns_packet_new(void) {
+flxDnsPacket* flx_dns_packet_new_query(guint max_size) {
     flxDnsPacket *p;
-    p = g_new(flxDnsPacket, 1);
-    p->size = p->rindex = 2*6;
-    memset(p->data, 0, p->size);
+
+    p = flx_dns_packet_new(max_size);
+    flx_dns_packet_set_field(p, FLX_DNS_FIELD_FLAGS, FLX_DNS_FLAGS(0, 0, 0, 0, 0, 0, 0, 0, 0, 0));
+    return p;
+}
+
+flxDnsPacket* flx_dns_packet_new_response(guint max_size) {
+    flxDnsPacket *p;
+
+    p = flx_dns_packet_new(max_size);
+    flx_dns_packet_set_field(p, FLX_DNS_FIELD_FLAGS, FLX_DNS_FLAGS(1, 0, 0, 0, 0, 0, 0, 0, 0, 0));
     return p;
 }
 
 void flx_dns_packet_free(flxDnsPacket *p) {
     g_assert(p);
+
+    if (p->name_table)
+        g_hash_table_destroy(p->name_table);
+    
     g_free(p);
 }
 
 void flx_dns_packet_set_field(flxDnsPacket *p, guint index, guint16 v) {
     g_assert(p);
-    g_assert(index < 2*6);
+    g_assert(index < FLX_DNS_PACKET_HEADER_SIZE);
     
-    ((guint16*) p->data)[index] = g_htons(v);
+    ((guint16*) FLX_DNS_PACKET_DATA(p))[index] = g_htons(v);
 }
 
 guint16 flx_dns_packet_get_field(flxDnsPacket *p, guint index) {
     g_assert(p);
-    g_assert(index < 2*6);
+    g_assert(index < FLX_DNS_PACKET_HEADER_SIZE);
 
-    return g_ntohs(((guint16*) p->data)[index]);
+    return g_ntohs(((guint16*) FLX_DNS_PACKET_DATA(p))[index]);
 }
 
-guint8* flx_dns_packet_append_name(flxDnsPacket *p, const gchar *name) {
-    guint8 *d, *f = NULL;
+/* Read the first label from string dest, unescape "\" and append it to *name */
+static gchar *unescape_label(gchar *dest, guint size, const gchar **name) {
+    guint i = 0;
+    gchar *d;
     
-    g_assert(p);
+    g_assert(dest);
+    g_assert(size > 0);
     g_assert(name);
+    g_assert(*name);
 
+    d = dest;
+    
     for (;;) {
-        guint n = strcspn(name, ".");
-        if (!n || n > 63)
+        if (i >= size)
             return NULL;
+
+        if (**name == '.') {
+            (*name)++;
+            break;
+        }
+        
+        if (**name == 0)
+            break;
         
-        d = flx_dns_packet_extend(p, n+1);
-        if (!f)
-            f = d;
-        d[0] = n;
-        memcpy(d+1, name, n);
+        if (**name == '\\') {
+            (*name) ++;
+            
+            if (**name == 0)
+                break;
+        }
+        
+        *(d++) = *((*name) ++);
+        i++;
+    }
 
-        name += n;
+    g_assert(i < size);
 
-        /* no trailing dot */
-        if (!*name)
-            break;
+    *d = 0;
 
-        name ++;
+    return dest;
+}
 
-        /* trailing dot */
-        if (!*name)
-            break;
+guint8* flx_dns_packet_append_name(flxDnsPacket *p, const gchar *name) {
+    guint8 *d, *saved_ptr = NULL;
+    guint saved_size;
+    
+    g_assert(p);
+    g_assert(name);
+
+    saved_size = p->size;
+    saved_ptr = flx_dns_packet_extend(p, 0);
+    
+    while (*name) {
+        guint n;
+        guint8* prev;
+        const gchar *pname;
+        char label[64];
+
+        /* Check whether we can compress this name. */
+
+        if (p->name_table && (prev = g_hash_table_lookup(p->name_table, name))) {
+            guint index;
+            
+            g_assert(prev >= FLX_DNS_PACKET_DATA(p));
+            index = (guint) (prev - FLX_DNS_PACKET_DATA(p));
+
+            g_assert(index < p->size);
+
+            if (index < 0x4000) {
+                guint16 *t;
+                if (!(t = (guint16*) flx_dns_packet_extend(p, sizeof(guint16))))
+                    return NULL;
+
+                *t = g_htons((0xC000 | index));
+                return saved_ptr;
+            }
+        }
+
+        pname = name;
+        
+        if (!(unescape_label(label, sizeof(label), &name)))
+            goto fail;
+
+        if (!(d = flx_dns_packet_append_string(p, label)))
+            goto fail;
+
+        if (!p->name_table)
+            p->name_table = g_hash_table_new_full((GHashFunc) flx_domain_hash, (GEqualFunc) flx_domain_equal, g_free, NULL);
+
+        g_hash_table_insert(p->name_table, g_strdup(pname), d);
     }
 
-    d = flx_dns_packet_extend(p, 1);
-    d[0] = 0;
+    if (!(d = flx_dns_packet_extend(p, 1)))
+        goto fail;
+    
+    *d = 0;
+
+    return saved_ptr;
 
-    return f;
+fail:
+    p->size = saved_size;
+    return NULL;
 }
 
 guint8* flx_dns_packet_append_uint16(flxDnsPacket *p, guint16 v) {
     guint8 *d;
-    
     g_assert(p);
     
-    d = flx_dns_packet_extend(p, sizeof(guint16));
-    *((guint16*) d) = g_htons(v);
+    if (!(d = flx_dns_packet_extend(p, sizeof(guint16))))
+        return NULL;
     
+    *((guint16*) d) = g_htons(v);
     return d;
 }
 
-guint8 *flx_dns_packet_extend(flxDnsPacket *p, guint l) {
+guint8 *flx_dns_packet_append_uint32(flxDnsPacket *p, guint32 v) {
     guint8 *d;
-    
     g_assert(p);
-    g_assert(p->size+l <= sizeof(p->data));
 
-    d = p->data + p->size;
-    p->size += l;
+    if (!(d = flx_dns_packet_extend(p, sizeof(guint32))))
+        return NULL;
     
+    *((guint32*) d) = g_htonl(v);
+
+    return d;
+}
+
+guint8 *flx_dns_packet_append_bytes(flxDnsPacket  *p, gconstpointer b, guint l) {
+    guint8* d;
+
+    g_assert(p);
+    g_assert(b);
+    g_assert(l);
+
+    if (!(d = flx_dns_packet_extend(p, l)))
+        return NULL;
+
+    memcpy(d, b, l);
     return d;
 }
 
-guint8 *flx_dns_packet_append_name_compressed(flxDnsPacket *p, const gchar *name, guint8 *prev) {
-    guint16 *d;
-    signed long k;
+guint8* flx_dns_packet_append_string(flxDnsPacket *p, const gchar *s) {
+    guint8* d;
+    guint k;
+    
     g_assert(p);
+    g_assert(s);
+
+    if ((k = strlen(s)) >= 255)
+        k = 255;
+    
+    if (!(d = flx_dns_packet_extend(p, k+1)))
+        return NULL;
+
+    *d = (guint8) k;
+    memcpy(d+1, s, k);
+
+    return d;
+}
 
-    if (!prev)
-        return flx_dns_packet_append_name(p, name);
+guint8 *flx_dns_packet_extend(flxDnsPacket *p, guint l) {
+    guint8 *d;
     
-    k = prev - p->data;
-    if (k < 0 || k >= 0x4000 || (guint) k >= p->size)
-        return flx_dns_packet_append_name(p, name);
+    g_assert(p);
 
-    d = (guint16*) flx_dns_packet_extend(p, sizeof(guint16));
-    *d = g_htons((0xC000 | k));
+    if (p->size+l > p->max_size)
+        return NULL;
+    
+    d = FLX_DNS_PACKET_DATA(p) + p->size;
+    p->size += l;
     
-    return prev;
+    return d;
 }
 
 gint flx_dns_packet_check_valid(flxDnsPacket *p) {
@@ -115,30 +244,54 @@ gint flx_dns_packet_check_valid(flxDnsPacket *p) {
     if (p->size < 12)
         return -1;
 
-    flags = flx_dns_packet_get_field(p, DNS_FIELD_FLAGS);
+    flags = flx_dns_packet_get_field(p, FLX_DNS_FIELD_FLAGS);
 
-    if (flags & DNS_FLAG_OPCODE || flags & DNS_FLAG_RCODE)
+    if (flags & FLX_DNS_FLAG_OPCODE || flags & FLX_DNS_FLAG_RCODE)
         return -1;
 
     return 0;
 }
 
-gint flx_dns_packet_check_valid_response(flxDnsPacket *p) {
-    guint16 flags;
+gint flx_dns_packet_is_query(flxDnsPacket *p) {
     g_assert(p);
     
-    if (flx_dns_packet_check_valid(p) < 0)
-        return -1;
+    return !(flx_dns_packet_get_field(p, FLX_DNS_FIELD_FLAGS) & FLX_DNS_FLAG_QR);
+}
 
-    flags = flx_dns_packet_get_field(p, DNS_FIELD_FLAGS);
+/* Read a label from a DNS packet, escape "\" and ".", append \0 */
+static gchar *escape_label(guint8* src, guint src_length, gchar **ret_name, guint *ret_name_length) {
+    gchar *r;
 
-    if (!(flags & DNS_FLAG_QR))
-        return -1;
+    g_assert(src);
+    g_assert(ret_name);
+    g_assert(*ret_name);
+    g_assert(ret_name_length);
+    g_assert(*ret_name_length > 0);
 
-    if (flx_dns_packet_get_field(p, DNS_FIELD_QDCOUNT) > 0)
-        return -1;
+    r = *ret_name;
 
-    return 0;
+    while (src_length > 0) {
+        if (*src == '.' || *src == '\\') {
+            if (*ret_name_length < 3)
+                return NULL;
+            
+            *((*ret_name) ++) = '\\';
+            (*ret_name_length) --;
+        }
+
+        if (*ret_name_length < 2)
+            return NULL;
+        
+        *((*ret_name)++) = *src;
+        (*ret_name_length) --;
+
+        src_length --;
+        src++;
+    }
+
+    **ret_name = 0;
+
+    return r;
 }
 
 static gint consume_labels(flxDnsPacket *p, guint index, gchar *ret_name, guint l) {
@@ -153,7 +306,7 @@ static gint consume_labels(flxDnsPacket *p, guint index, gchar *ret_name, guint
         if (index+1 > p->size)
             return -1;
 
-        n = p->data[index];
+        n = FLX_DNS_PACKET_DATA(p)[index];
 
         if (!n) {
             index++;
@@ -184,10 +337,10 @@ static gint consume_labels(flxDnsPacket *p, guint index, gchar *ret_name, guint
             } else
                 first_label = 0;
 
-            memcpy(ret_name, p->data + index, n);
+            if (!(escape_label(FLX_DNS_PACKET_DATA(p) + index, n, &ret_name, &l)))
+                return -1;
+
             index += n;
-            ret_name += n;
-            l -= n;
             
             if (!compressed)
                 ret += n;
@@ -197,7 +350,7 @@ static gint consume_labels(flxDnsPacket *p, guint index, gchar *ret_name, guint
             if (index+2 > p->size)
                 return -1;
 
-            index = ((guint) (p->data[index] & ~0xC0)) << 8 | p->data[index+1];
+            index = ((guint) (FLX_DNS_PACKET_DATA(p)[index] & ~0xC0)) << 8 | FLX_DNS_PACKET_DATA(p)[index+1];
 
             if (!compressed)
                 ret += 2;
@@ -225,7 +378,7 @@ gint flx_dns_packet_consume_uint16(flxDnsPacket *p, guint16 *ret_v) {
     if (p->rindex + sizeof(guint16) > p->size)
         return -1;
 
-    *ret_v = g_ntohs(*((guint16*) (p->data + p->rindex)));
+    *ret_v = g_ntohs(*((guint16*) (FLX_DNS_PACKET_DATA(p) + p->rindex)));
     p->rindex += sizeof(guint16);
 
     return 0;
@@ -238,7 +391,7 @@ gint flx_dns_packet_consume_uint32(flxDnsPacket *p, guint32 *ret_v) {
     if (p->rindex + sizeof(guint32) > p->size)
         return -1;
 
-    *ret_v = g_ntohl(*((guint32*) (p->data + p->rindex)));
+    *ret_v = g_ntohl(*((guint32*) (FLX_DNS_PACKET_DATA(p) + p->rindex)));
     p->rindex += sizeof(guint32);
     
     return 0;
@@ -252,12 +405,49 @@ gint flx_dns_packet_consume_bytes(flxDnsPacket *p, gpointer ret_data, guint l) {
     if (p->rindex + l > p->size)
         return -1;
 
-    memcpy(ret_data, p->data + p->rindex, l);
+    memcpy(ret_data, FLX_DNS_PACKET_DATA(p) + p->rindex, l);
     p->rindex += l;
 
     return 0;
 }
 
+gint flx_dns_packet_consume_string(flxDnsPacket *p, gchar *ret_string, guint l) {
+    guint k;
+    
+    g_assert(p);
+    g_assert(ret_string);
+    g_assert(l > 0);
+
+    if (p->rindex >= p->size)
+        return -1;
+
+    k = FLX_DNS_PACKET_DATA(p)[p->rindex];
+
+    if (p->rindex+1+k > p->size)
+        return -1;
+
+    if (l > k+1)
+        l = k+1;
+
+    memcpy(ret_string, FLX_DNS_PACKET_DATA(p)+p->rindex+1, l-1);
+    ret_string[l-1] = 0;
+
+    
+    p->rindex += 1+k;
+
+    return 0;
+    
+}
+
+gconstpointer flx_dns_packet_get_rptr(flxDnsPacket *p) {
+    g_assert(p);
+    
+    if (p->rindex > p->size)
+        return NULL;
+
+    return FLX_DNS_PACKET_DATA(p) + p->rindex;
+}
+
 gint flx_dns_packet_skip(flxDnsPacket *p, guint length) {
     g_assert(p);
 
@@ -267,3 +457,292 @@ gint flx_dns_packet_skip(flxDnsPacket *p, guint length) {
     p->rindex += length;
     return 0;
 }
+
+flxRecord* flx_dns_packet_consume_record(flxDnsPacket *p, gboolean *ret_cache_flush) {
+    gchar name[257], buf[257];
+    guint16 type, class;
+    guint32 ttl;
+    guint16 rdlength;
+    gconstpointer data;
+    flxRecord *r = NULL;
+    gconstpointer start;
+
+    g_assert(p);
+    g_assert(ret_cache_flush);
+
+/*     g_message("consume_record()"); */
+
+    if (flx_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
+        flx_dns_packet_consume_uint16(p, &type) < 0 ||
+        flx_dns_packet_consume_uint16(p, &class) < 0 ||
+        flx_dns_packet_consume_uint32(p, &ttl) < 0 ||
+        flx_dns_packet_consume_uint16(p, &rdlength) < 0 ||
+        p->rindex + rdlength > p->size)
+        
+        goto fail;
+
+/*     g_message("name = %s, rdlength = %u", name, rdlength); */
+    
+    start = flx_dns_packet_get_rptr(p);
+
+    r = flx_record_new_full(name, class, type);
+    
+    switch (type) {
+        case FLX_DNS_TYPE_PTR:
+        case FLX_DNS_TYPE_CNAME:
+
+/*             g_message("ptr"); */
+            
+            if (flx_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
+                goto fail;
+
+            r->data.ptr.name = g_strdup(buf);
+            break;
+
+            
+        case FLX_DNS_TYPE_SRV:
+
+/*             g_message("srv"); */
+            
+            if (flx_dns_packet_consume_uint16(p, &r->data.srv.priority) < 0 ||
+                flx_dns_packet_consume_uint16(p, &r->data.srv.weight) < 0 ||
+                flx_dns_packet_consume_uint16(p, &r->data.srv.port) < 0 ||
+                flx_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
+                goto fail;
+            
+            r->data.srv.name = g_strdup(buf);
+            break;
+
+        case FLX_DNS_TYPE_HINFO:
+            
+/*             g_message("hinfo"); */
+
+            if (flx_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
+                goto fail;
+
+            r->data.hinfo.cpu = g_strdup(buf);
+
+            if (flx_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
+                goto fail;
+
+            r->data.hinfo.os = g_strdup(buf);
+            break;
+
+        case FLX_DNS_TYPE_TXT:
+
+/*             g_message("txt"); */
+
+            if (rdlength > 0) {
+                r->data.txt.string_list = flx_string_list_parse(flx_dns_packet_get_rptr(p), rdlength);
+                
+                if (flx_dns_packet_skip(p, rdlength) < 0)
+                    goto fail;
+            } else
+                r->data.txt.string_list = NULL;
+            
+            break;
+
+        case FLX_DNS_TYPE_A:
+
+/*             g_message("A"); */
+
+            if (flx_dns_packet_consume_bytes(p, &r->data.a.address, sizeof(flxIPv4Address)) < 0)
+                goto fail;
+            
+            break;
+
+        case FLX_DNS_TYPE_AAAA:
+
+/*             g_message("aaaa"); */
+            
+            if (flx_dns_packet_consume_bytes(p, &r->data.aaaa.address, sizeof(flxIPv6Address)) < 0)
+                goto fail;
+            
+            break;
+            
+        default:
+
+/*             g_message("generic"); */
+            
+            if (rdlength > 0) {
+
+                r->data.generic.data = g_memdup(flx_dns_packet_get_rptr(p), rdlength);
+                
+                if (flx_dns_packet_skip(p, rdlength) < 0)
+                    goto fail;
+            }
+
+            break;
+    }
+
+/*     g_message("%i == %u ?", (guint8*) flx_dns_packet_get_rptr(p) - (guint8*) start, rdlength); */
+    
+    /* Check if we read enough data */
+    if ((guint8*) flx_dns_packet_get_rptr(p) - (guint8*) start != rdlength)
+        goto fail;
+    
+    *ret_cache_flush = !!(class & FLX_DNS_CACHE_FLUSH);
+    class &= ~ FLX_DNS_CACHE_FLUSH;
+
+    r->ttl = ttl;
+
+    return r;
+
+fail:
+    if (r)
+        flx_record_unref(r);
+
+    return NULL;
+}
+
+flxKey* flx_dns_packet_consume_key(flxDnsPacket *p) {
+    gchar name[256];
+    guint16 type, class;
+
+    g_assert(p);
+
+    if (flx_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
+        flx_dns_packet_consume_uint16(p, &type) < 0 ||
+        flx_dns_packet_consume_uint16(p, &class) < 0)
+        return NULL;
+
+    class &= ~ FLX_DNS_CACHE_FLUSH;
+
+    return flx_key_new(name, class, type);
+}
+
+guint8* flx_dns_packet_append_key(flxDnsPacket *p, flxKey *k) {
+    guint8 *t;
+    guint size;
+    
+    g_assert(p);
+    g_assert(k);
+
+    size = p->size;
+    
+    if (!(t = flx_dns_packet_append_name(p, k->name)) ||
+        !flx_dns_packet_append_uint16(p, k->type) ||
+        !flx_dns_packet_append_uint16(p, k->class)) {
+        p->size = size;
+        return NULL;
+    }
+
+    return t;
+}
+
+guint8* flx_dns_packet_append_record(flxDnsPacket *p, flxRecord *r, gboolean cache_flush) {
+    guint8 *t, *l, *start;
+    guint size;
+
+    g_assert(p);
+    g_assert(r);
+
+    size = p->size;
+
+    if (!(t = flx_dns_packet_append_name(p, r->key->name)) ||
+        !flx_dns_packet_append_uint16(p, r->key->type) ||
+        !flx_dns_packet_append_uint16(p, cache_flush ? (r->key->class | FLX_DNS_CACHE_FLUSH) : (r->key->class &~ FLX_DNS_CACHE_FLUSH)) ||
+        !flx_dns_packet_append_uint32(p, r->ttl) ||
+        !(l = flx_dns_packet_append_uint16(p, 0)))
+        goto fail;
+
+    start = flx_dns_packet_extend(p, 0);
+
+    switch (r->key->type) {
+        
+        case FLX_DNS_TYPE_PTR:
+        case FLX_DNS_TYPE_CNAME :
+
+            if (!(flx_dns_packet_append_name(p, r->data.ptr.name)))
+                goto fail;
+            
+            break;
+
+        case FLX_DNS_TYPE_SRV:
+
+            if (!flx_dns_packet_append_uint16(p, r->data.srv.priority) ||
+                !flx_dns_packet_append_uint16(p, r->data.srv.weight) ||
+                !flx_dns_packet_append_uint16(p, r->data.srv.port) ||
+                !flx_dns_packet_append_name(p, r->data.srv.name))
+                goto fail;
+
+            break;
+
+        case FLX_DNS_TYPE_HINFO:
+            if (!flx_dns_packet_append_string(p, r->data.hinfo.cpu) ||
+                !flx_dns_packet_append_string(p, r->data.hinfo.os))
+                goto fail;
+
+            break;
+
+        case FLX_DNS_TYPE_TXT: {
+
+            guint8 *data;
+            guint size;
+
+            size = flx_string_list_serialize(r->data.txt.string_list, NULL, 0);
+
+/*             g_message("appending string: %u %p", size, r->data.txt.string_list); */
+
+            if (!(data = flx_dns_packet_extend(p, size)))
+                goto fail;
+
+            flx_string_list_serialize(r->data.txt.string_list, data, size);
+            break;
+        }
+
+
+        case FLX_DNS_TYPE_A:
+
+            if (!flx_dns_packet_append_bytes(p, &r->data.a.address, sizeof(r->data.a.address)))
+                goto fail;
+            
+            break;
+
+        case FLX_DNS_TYPE_AAAA:
+            
+            if (!flx_dns_packet_append_bytes(p, &r->data.aaaa.address, sizeof(r->data.aaaa.address)))
+                goto fail;
+            
+            break;
+            
+        default:
+
+            if (r->data.generic.size &&
+                flx_dns_packet_append_bytes(p, r->data.generic.data, r->data.generic.size))
+                goto fail;
+
+            break;
+    }
+
+
+
+    
+    size = flx_dns_packet_extend(p, 0) - start;
+    g_assert(size <= 0xFFFF);
+
+/*     g_message("appended %u", size); */
+
+    * (guint16*) l = g_htons((guint16) size);
+    
+    return t;
+
+
+fail:
+    p->size = size;
+    return NULL;
+}
+
+gboolean flx_dns_packet_is_empty(flxDnsPacket *p) {
+    g_assert(p);
+
+    return p->size <= FLX_DNS_PACKET_HEADER_SIZE;
+}
+
+guint flx_dns_packet_space(flxDnsPacket *p) {
+    g_assert(p);
+
+    g_assert(p->size <= p->max_size);
+    
+    return p->max_size - p->size;
+}