Wed Aug 18 22:33:40 2010

Asterisk developer's documentation


acl.c

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 1999 - 2006, Digium, Inc.
00005  *
00006  * Mark Spencer <markster@digium.com>
00007  *
00008  * See http://www.asterisk.org for more information about
00009  * the Asterisk project. Please do not directly contact
00010  * any of the maintainers of this project for assistance;
00011  * the project provides a web site, mailing lists and IRC
00012  * channels for your use.
00013  *
00014  * This program is free software, distributed under the terms of
00015  * the GNU General Public License Version 2. See the LICENSE file
00016  * at the top of the source tree.
00017  */
00018 
00019 /*! \file
00020  *
00021  * \brief Various sorts of access control
00022  *
00023  * \author Mark Spencer <markster@digium.com>
00024  */
00025 
00026 #include "asterisk.h"
00027 
00028 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 248948 $")
00029 
00030 #include "asterisk/network.h"
00031 
00032 #if defined(__OpenBSD__) || defined(__NetBSD__) || defined(__FreeBSD__) || defined(__Darwin__)
00033 #include <fcntl.h>
00034 #include <net/route.h>
00035 #endif
00036 
00037 #if defined(SOLARIS)
00038 #include <sys/sockio.h>
00039 #include <net/if.h>
00040 #elif defined(HAVE_GETIFADDRS)
00041 #include <ifaddrs.h>
00042 #endif
00043 
00044 #include "asterisk/acl.h"
00045 #include "asterisk/channel.h"
00046 #include "asterisk/utils.h"
00047 #include "asterisk/lock.h"
00048 #include "asterisk/srv.h"
00049 
00050 #if (!defined(SOLARIS) && !defined(HAVE_GETIFADDRS))
00051 static int get_local_address(struct in_addr *ourip)
00052 {
00053    return -1;
00054 }
00055 #else
00056 static void score_address(const struct sockaddr_in *sin, struct in_addr *best_addr, int *best_score)
00057 {
00058    const char *address;
00059    int score;
00060 
00061    address = ast_inet_ntoa(sin->sin_addr);
00062 
00063    /* RFC 1700 alias for the local network */
00064    if (address[0] == '0')
00065       score = -25;
00066    /* RFC 1700 localnet */
00067    else if (strncmp(address, "127", 3) == 0)
00068       score = -20;
00069    /* RFC 1918 non-public address space */
00070    else if (strncmp(address, "10.", 3) == 0)
00071       score = -5;
00072    /* RFC 1918 non-public address space */
00073    else if (strncmp(address, "172", 3) == 0) {
00074       /* 172.16.0.0 - 172.19.255.255, but not 172.160.0.0 - 172.169.255.255 */
00075       if (address[4] == '1' && address[5] >= '6' && address[6] == '.')
00076          score = -5;
00077       /* 172.20.0.0 - 172.29.255.255, but not 172.200.0.0 - 172.255.255.255 nor 172.2.0.0 - 172.2.255.255 */
00078       else if (address[4] == '2' && address[6] == '.')
00079          score = -5;
00080       /* 172.30.0.0 - 172.31.255.255 */
00081       else if (address[4] == '3' && address[5] <= '1')
00082          score = -5;
00083       /* All other 172 addresses are public */
00084       else
00085          score = 0;
00086    /* RFC 2544 Benchmark test range */
00087    } else if (strncmp(address, "198.1", 5) == 0 && address[5] >= '8' && address[6] == '.')
00088       score = -10;
00089    /* RFC 1918 non-public address space */
00090    else if (strncmp(address, "192.168", 7) == 0)
00091       score = -5;
00092    /* RFC 3330 Zeroconf network */
00093    else if (strncmp(address, "169.254", 7) == 0)
00094       /*!\note Better score than a test network, but not quite as good as RFC 1918
00095        * address space.  The reason is that some Linux distributions automatically
00096        * configure a Zeroconf address before trying DHCP, so we want to prefer a
00097        * DHCP lease to a Zeroconf address.
00098        */
00099       score = -10;
00100    /* RFC 3330 Test network */
00101    else if (strncmp(address, "192.0.2.", 8) == 0)
00102       score = -15;
00103    /* Every other address should be publically routable */
00104    else
00105       score = 0;
00106 
00107    if (score > *best_score) {
00108       *best_score = score;
00109       memcpy(best_addr, &sin->sin_addr, sizeof(*best_addr));
00110    }
00111 }
00112 
00113 static int get_local_address(struct in_addr *ourip)
00114 {
00115    int s, res = -1;
00116 #ifdef SOLARIS
00117    struct lifreq *ifr = NULL;
00118    struct lifnum ifn;
00119    struct lifconf ifc;
00120    struct sockaddr_in *sa;
00121    char *buf = NULL;
00122    int bufsz, x;
00123 #endif /* SOLARIS */
00124 #if defined(__OpenBSD__) || defined(__NetBSD__) || defined(__FreeBSD__) || defined(__linux__) || defined(__Darwin__)
00125    struct ifaddrs *ifap, *ifaphead;
00126    int rtnerr;
00127    const struct sockaddr_in *sin;
00128 #endif /* BSD_OR_LINUX */
00129    struct in_addr best_addr;
00130    int best_score = -100;
00131    memset(&best_addr, 0, sizeof(best_addr));
00132 
00133 #if defined(__OpenBSD__) || defined(__NetBSD__) || defined(__FreeBSD__) || defined(__linux__) || defined(__Darwin__)
00134    rtnerr = getifaddrs(&ifaphead);
00135    if (rtnerr) {
00136       perror(NULL);
00137       return -1;
00138    }
00139 #endif /* BSD_OR_LINUX */
00140 
00141    s = socket(AF_INET, SOCK_STREAM, 0);
00142 
00143    if (s > 0) {
00144 #if defined(__OpenBSD__) || defined(__NetBSD__) || defined(__FreeBSD__) || defined(__linux__) || defined(__Darwin__)
00145       for (ifap = ifaphead; ifap; ifap = ifap->ifa_next) {
00146 
00147          if (ifap->ifa_addr && ifap->ifa_addr->sa_family == AF_INET) {
00148             sin = (const struct sockaddr_in *) ifap->ifa_addr;
00149             score_address(sin, &best_addr, &best_score);
00150             res = 0;
00151 
00152             if (best_score == 0)
00153                break;
00154          }
00155       }
00156 #endif /* BSD_OR_LINUX */
00157 
00158       /* There is no reason whatsoever that this shouldn't work on Linux or BSD also. */
00159 #ifdef SOLARIS
00160       /* Get a count of interfaces on the machine */
00161       ifn.lifn_family = AF_INET;
00162       ifn.lifn_flags = 0;
00163       ifn.lifn_count = 0;
00164       if (ioctl(s, SIOCGLIFNUM, &ifn) < 0) {
00165          close(s);
00166          return -1;
00167       }
00168 
00169       bufsz = ifn.lifn_count * sizeof(struct lifreq);
00170       if (!(buf = malloc(bufsz))) {
00171          close(s);
00172          return -1;
00173       }
00174       memset(buf, 0, bufsz);
00175 
00176       /* Get a list of interfaces on the machine */
00177       ifc.lifc_len = bufsz;
00178       ifc.lifc_buf = buf;
00179       ifc.lifc_family = AF_INET;
00180       ifc.lifc_flags = 0;
00181       if (ioctl(s, SIOCGLIFCONF, &ifc) < 0) {
00182          close(s);
00183          free(buf);
00184          return -1;
00185       }
00186 
00187       for (ifr = ifc.lifc_req, x = 0; x < ifn.lifn_count; ifr++, x++) {
00188          sa = (struct sockaddr_in *)&(ifr->lifr_addr);
00189          score_address(sa, &best_addr, &best_score);
00190          res = 0;
00191 
00192          if (best_score == 0)
00193             break;
00194       }
00195 
00196       free(buf);
00197 #endif /* SOLARIS */
00198       
00199       close(s);
00200    }
00201 #if defined(__OpenBSD__) || defined(__NetBSD__) || defined(__FreeBSD__) || defined(__linux__) || defined(__Darwin__)
00202    freeifaddrs(ifaphead);
00203 #endif /* BSD_OR_LINUX */
00204 
00205    if (res == 0 && ourip)
00206       memcpy(ourip, &best_addr, sizeof(*ourip));
00207    return res;
00208 }
00209 #endif /* HAVE_GETIFADDRS */
00210 
00211 /* Free HA structure */
00212 void ast_free_ha(struct ast_ha *ha)
00213 {
00214    struct ast_ha *hal;
00215    while (ha) {
00216       hal = ha;
00217       ha = ha->next;
00218       ast_free(hal);
00219    }
00220 }
00221 
00222 /* Copy HA structure */
00223 void ast_copy_ha(const struct ast_ha *from, struct ast_ha *to)
00224 {
00225    memcpy(&to->netaddr, &from->netaddr, sizeof(from->netaddr));
00226    memcpy(&to->netmask, &from->netmask, sizeof(from->netmask));
00227    to->sense = from->sense;
00228 }
00229 
00230 /* Create duplicate of ha structure */
00231 static struct ast_ha *ast_duplicate_ha(struct ast_ha *original)
00232 {
00233    struct ast_ha *new_ha;
00234 
00235    if ((new_ha = ast_malloc(sizeof(*new_ha)))) {
00236       /* Copy from original to new object */
00237       ast_copy_ha(original, new_ha);
00238    }
00239 
00240    return new_ha;
00241 }
00242 
00243 /* Create duplicate HA link list */
00244 /*  Used in chan_sip2 templates */
00245 struct ast_ha *ast_duplicate_ha_list(struct ast_ha *original)
00246 {
00247    struct ast_ha *start = original;
00248    struct ast_ha *ret = NULL;
00249    struct ast_ha *current, *prev = NULL;
00250 
00251    while (start) {
00252       current = ast_duplicate_ha(start);  /* Create copy of this object */
00253       if (prev)
00254          prev->next = current;      /* Link previous to this object */
00255 
00256       if (!ret)
00257          ret = current;    /* Save starting point */
00258 
00259       start = start->next;    /* Go to next object */
00260       prev = current;         /* Save pointer to this object */
00261    }
00262    return ret;             /* Return start of list */
00263 }
00264 
00265 struct ast_ha *ast_append_ha(const char *sense, const char *stuff, struct ast_ha *path, int *error)
00266 {
00267    struct ast_ha *ha;
00268    char *nm;
00269    struct ast_ha *prev = NULL;
00270    struct ast_ha *ret;
00271    int x;
00272    char *tmp = ast_strdupa(stuff);
00273 
00274    ret = path;
00275    while (path) {
00276       prev = path;
00277       path = path->next;
00278    }
00279 
00280    ha = ast_malloc(sizeof(*ha));
00281    if (!ha)
00282       return ret;
00283 
00284    nm = strchr(tmp, '/');
00285    if (!nm) {
00286       /* assume /32. Yes, htonl does not do anything for this particular mask
00287          but we better use it to show we remember about byte order */
00288       ha->netmask.s_addr = htonl(0xFFFFFFFF);
00289    } else {
00290       *nm = '\0';
00291       nm++;
00292 
00293       if (!strchr(nm, '.')) {
00294          if ((sscanf(nm, "%30d", &x) == 1) && (x >= 0) && (x <= 32))
00295             if (x == 0) {
00296                /* This is special-cased to prevent unpredictable
00297                 * behavior of shifting left 32 bits
00298                 */
00299                ha->netmask.s_addr = 0;
00300             } else {
00301                ha->netmask.s_addr = htonl(0xFFFFFFFF << (32 - x));
00302             }
00303          else {
00304             ast_log(LOG_WARNING, "Invalid CIDR in %s\n", stuff);
00305             ast_free(ha);
00306             if (error)
00307                *error = 1;
00308             return ret;
00309          }
00310       } else if (!inet_aton(nm, &ha->netmask)) {
00311          ast_log(LOG_WARNING, "Invalid mask in %s\n", stuff);
00312          ast_free(ha);
00313          if (error)
00314             *error = 1;
00315          return ret;
00316       }
00317    }
00318 
00319    if (!inet_aton(tmp, &ha->netaddr)) {
00320       ast_log(LOG_WARNING, "Invalid IP address in %s\n", stuff);
00321       ast_free(ha);
00322       if (error)
00323          *error = 1;
00324       return ret;
00325    }
00326 
00327    ha->netaddr.s_addr &= ha->netmask.s_addr;
00328 
00329    ha->sense = strncasecmp(sense, "p", 1) ? AST_SENSE_DENY : AST_SENSE_ALLOW;
00330 
00331    ha->next = NULL;
00332    if (prev) {
00333       prev->next = ha;
00334    } else {
00335       ret = ha;
00336    }
00337 
00338    ast_debug(1, "%s/%s sense %d appended to acl for peer\n", ast_strdupa(ast_inet_ntoa(ha->netaddr)), ast_strdupa(ast_inet_ntoa(ha->netmask)), ha->sense);
00339 
00340    return ret;
00341 }
00342 
00343 int ast_apply_ha(struct ast_ha *ha, struct sockaddr_in *sin)
00344 {
00345    /* Start optimistic */
00346    int res = AST_SENSE_ALLOW;
00347    while (ha) {
00348 #if 0 /* debugging code */
00349       char iabuf[INET_ADDRSTRLEN];
00350       char iabuf2[INET_ADDRSTRLEN];
00351       /* DEBUG */
00352       ast_copy_string(iabuf, ast_inet_ntoa(sin->sin_addr), sizeof(iabuf));
00353       ast_copy_string(iabuf2, ast_inet_ntoa(ha->netaddr), sizeof(iabuf2));
00354       ast_debug(1, "##### Testing %s with %s\n", iabuf, iabuf2);
00355 #endif
00356       /* For each rule, if this address and the netmask = the net address
00357          apply the current rule */
00358       if ((sin->sin_addr.s_addr & ha->netmask.s_addr) == ha->netaddr.s_addr)
00359          res = ha->sense;
00360       ha = ha->next;
00361    }
00362    return res;
00363 }
00364 
00365 int ast_get_ip_or_srv(struct sockaddr_in *sin, const char *value, const char *service)
00366 {
00367    struct hostent *hp;
00368    struct ast_hostent ahp;
00369    char srv[256];
00370    char host[256];
00371    int tportno = ntohs(sin->sin_port);
00372    if (service) {
00373       snprintf(srv, sizeof(srv), "%s.%s", service, value);
00374       if (ast_get_srv(NULL, host, sizeof(host), &tportno, srv) > 0) {
00375          sin->sin_port = htons(tportno);
00376          value = host;
00377       }
00378    }
00379    hp = ast_gethostbyname(value, &ahp);
00380    if (hp) {
00381       memcpy(&sin->sin_addr, hp->h_addr, sizeof(sin->sin_addr));
00382    } else {
00383       ast_log(LOG_WARNING, "Unable to lookup '%s'\n", value);
00384       return -1;
00385    }
00386    return 0;
00387 }
00388 
00389 struct dscp_codepoint {
00390    char *name;
00391    unsigned int space;
00392 };
00393 
00394 /* IANA registered DSCP codepoints */
00395 
00396 static const struct dscp_codepoint dscp_pool1[] = {
00397    { "CS0", 0x00 },
00398    { "CS1", 0x08 },
00399    { "CS2", 0x10 },
00400    { "CS3", 0x18 },
00401    { "CS4", 0x20 },
00402    { "CS5", 0x28 },
00403    { "CS6", 0x30 },
00404    { "CS7", 0x38 },
00405    { "AF11", 0x0A },
00406    { "AF12", 0x0C },
00407    { "AF13", 0x0E },
00408    { "AF21", 0x12 },
00409    { "AF22", 0x14 },
00410    { "AF23", 0x16 },
00411    { "AF31", 0x1A },
00412    { "AF32", 0x1C },
00413    { "AF33", 0x1E },
00414    { "AF41", 0x22 },
00415    { "AF42", 0x24 },
00416    { "AF43", 0x26 },
00417    { "EF", 0x2E },
00418 };
00419 
00420 int ast_str2cos(const char *value, unsigned int *cos) 
00421 {
00422    int fval;
00423 
00424    if (sscanf(value, "%30d", &fval) == 1) {
00425       if (fval < 8) {
00426           *cos = fval;
00427           return 0;
00428       }
00429    }
00430 
00431    return -1;
00432 }
00433 
00434 int ast_str2tos(const char *value, unsigned int *tos)
00435 {
00436    int fval;
00437    unsigned int x;
00438 
00439    if (sscanf(value, "%30i", &fval) == 1) {
00440       *tos = fval & 0xFF;
00441       return 0;
00442    }
00443 
00444    for (x = 0; x < ARRAY_LEN(dscp_pool1); x++) {
00445       if (!strcasecmp(value, dscp_pool1[x].name)) {
00446          *tos = dscp_pool1[x].space << 2;
00447          return 0;
00448       }
00449    }
00450 
00451    return -1;
00452 }
00453 
00454 const char *ast_tos2str(unsigned int tos)
00455 {
00456    unsigned int x;
00457 
00458    for (x = 0; x < ARRAY_LEN(dscp_pool1); x++) {
00459       if (dscp_pool1[x].space == (tos >> 2))
00460          return dscp_pool1[x].name;
00461    }
00462 
00463    return "unknown";
00464 }
00465 
00466 int ast_get_ip(struct sockaddr_in *sin, const char *value)
00467 {
00468    return ast_get_ip_or_srv(sin, value, NULL);
00469 }
00470 
00471 int ast_ouraddrfor(struct in_addr *them, struct in_addr *us)
00472 {
00473    int s;
00474    struct sockaddr_in sin;
00475    socklen_t slen;
00476 
00477    s = socket(PF_INET, SOCK_DGRAM, 0);
00478    if (s < 0) {
00479       ast_log(LOG_ERROR, "Cannot create socket\n");
00480       return -1;
00481    }
00482    sin.sin_family = AF_INET;
00483    sin.sin_port = htons(5060);
00484    sin.sin_addr = *them;
00485    if (connect(s, (struct sockaddr *)&sin, sizeof(sin))) {
00486       ast_log(LOG_WARNING, "Cannot connect\n");
00487       close(s);
00488       return -1;
00489    }
00490    slen = sizeof(sin);
00491    if (getsockname(s, (struct sockaddr *)&sin, &slen)) {
00492       ast_log(LOG_WARNING, "Cannot get socket name\n");
00493       close(s);
00494       return -1;
00495    }
00496    close(s);
00497    ast_debug(3, "Found IP address for this socket\n");
00498    *us = sin.sin_addr;
00499    return 0;
00500 }
00501 
00502 int ast_find_ourip(struct in_addr *ourip, struct sockaddr_in bindaddr)
00503 {
00504    char ourhost[MAXHOSTNAMELEN] = "";
00505    struct ast_hostent ahp;
00506    struct hostent *hp;
00507    struct in_addr saddr;
00508 
00509    /* just use the bind address if it is nonzero */
00510    if (ntohl(bindaddr.sin_addr.s_addr)) {
00511       memcpy(ourip, &bindaddr.sin_addr, sizeof(*ourip));
00512       ast_debug(3, "Attached to given IP address\n");
00513       return 0;
00514    }
00515    /* try to use our hostname */
00516    if (gethostname(ourhost, sizeof(ourhost) - 1)) {
00517       ast_log(LOG_WARNING, "Unable to get hostname\n");
00518    } else {
00519       hp = ast_gethostbyname(ourhost, &ahp);
00520       if (hp) {
00521          memcpy(ourip, hp->h_addr, sizeof(*ourip));
00522          ast_debug(3, "Found one IP address based on local hostname %s.\n", ourhost);
00523          return 0;
00524       }
00525    }
00526    ast_debug(3, "Trying to check A.ROOT-SERVERS.NET and get our IP address for that connection\n");
00527    /* A.ROOT-SERVERS.NET. */
00528    if (inet_aton("198.41.0.4", &saddr) && !ast_ouraddrfor(&saddr, ourip))
00529       return 0;
00530    return get_local_address(ourip);
00531 }
00532 

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