// SPDX-License-Identifier: GPL-2.0-only
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/* SIP extension for IP connection tracking.
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*
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* (C) 2005 by Christian Hentschel <chentschel@arnet.com.ar>
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* based on RR's ip_conntrack_ftp.c and other modules.
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* (C) 2007 United Security Providers
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* (C) 2007, 2008 Patrick McHardy <kaber@trash.net>
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/ctype.h>
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#include <linux/skbuff.h>
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#include <linux/inet.h>
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#include <linux/in.h>
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#include <linux/udp.h>
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#include <linux/tcp.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter_ipv4.h>
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#include <linux/netfilter_ipv6.h>
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#include <net/netfilter/nf_conntrack.h>
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#include <net/netfilter/nf_conntrack_core.h>
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#include <net/netfilter/nf_conntrack_expect.h>
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#include <net/netfilter/nf_conntrack_helper.h>
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#include <net/netfilter/nf_conntrack_zones.h>
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#include <linux/netfilter/nf_conntrack_sip.h>
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#define HELPER_NAME "sip"
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>");
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MODULE_DESCRIPTION("SIP connection tracking helper");
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MODULE_ALIAS("ip_conntrack_sip");
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MODULE_ALIAS_NFCT_HELPER(HELPER_NAME);
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#define MAX_PORTS 8
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static unsigned short ports[MAX_PORTS];
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static unsigned int ports_c;
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module_param_array(ports, ushort, &ports_c, 0400);
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MODULE_PARM_DESC(ports, "port numbers of SIP servers");
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static unsigned int sip_timeout __read_mostly = SIP_TIMEOUT;
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module_param(sip_timeout, uint, 0600);
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MODULE_PARM_DESC(sip_timeout, "timeout for the master SIP session");
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static int sip_direct_signalling __read_mostly = 1;
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module_param(sip_direct_signalling, int, 0600);
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MODULE_PARM_DESC(sip_direct_signalling, "expect incoming calls from registrar "
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"only (default 1)");
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static int sip_direct_media __read_mostly = 1;
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module_param(sip_direct_media, int, 0600);
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MODULE_PARM_DESC(sip_direct_media, "Expect Media streams between signalling "
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"endpoints only (default 1)");
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static int sip_external_media __read_mostly = 0;
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module_param(sip_external_media, int, 0600);
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MODULE_PARM_DESC(sip_external_media, "Expect Media streams between external "
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"endpoints (default 0)");
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const struct nf_nat_sip_hooks *nf_nat_sip_hooks;
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EXPORT_SYMBOL_GPL(nf_nat_sip_hooks);
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static int string_len(const struct nf_conn *ct, const char *dptr,
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const char *limit, int *shift)
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{
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int len = 0;
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while (dptr < limit && isalpha(*dptr)) {
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dptr++;
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len++;
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}
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return len;
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}
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static int digits_len(const struct nf_conn *ct, const char *dptr,
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const char *limit, int *shift)
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{
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int len = 0;
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while (dptr < limit && isdigit(*dptr)) {
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dptr++;
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len++;
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}
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return len;
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}
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static int iswordc(const char c)
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{
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if (isalnum(c) || c == '!' || c == '"' || c == '%' ||
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(c >= '(' && c <= '+') || c == ':' || c == '<' || c == '>' ||
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c == '?' || (c >= '[' && c <= ']') || c == '_' || c == '`' ||
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c == '{' || c == '}' || c == '~' || (c >= '-' && c <= '/') ||
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c == '\'')
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return 1;
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return 0;
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}
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static int word_len(const char *dptr, const char *limit)
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{
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int len = 0;
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while (dptr < limit && iswordc(*dptr)) {
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dptr++;
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len++;
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}
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return len;
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}
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static int callid_len(const struct nf_conn *ct, const char *dptr,
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const char *limit, int *shift)
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{
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int len, domain_len;
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len = word_len(dptr, limit);
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dptr += len;
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if (!len || dptr == limit || *dptr != '@')
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return len;
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dptr++;
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len++;
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domain_len = word_len(dptr, limit);
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if (!domain_len)
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return 0;
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return len + domain_len;
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}
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/* get media type + port length */
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static int media_len(const struct nf_conn *ct, const char *dptr,
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const char *limit, int *shift)
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{
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int len = string_len(ct, dptr, limit, shift);
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dptr += len;
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if (dptr >= limit || *dptr != ' ')
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return 0;
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len++;
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dptr++;
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return len + digits_len(ct, dptr, limit, shift);
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}
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static int sip_parse_addr(const struct nf_conn *ct, const char *cp,
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const char **endp, union nf_inet_addr *addr,
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const char *limit, bool delim)
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{
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const char *end;
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int ret;
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if (!ct)
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return 0;
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memset(addr, 0, sizeof(*addr));
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switch (nf_ct_l3num(ct)) {
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case AF_INET:
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ret = in4_pton(cp, limit - cp, (u8 *)&addr->ip, -1, &end);
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if (ret == 0)
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return 0;
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break;
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case AF_INET6:
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if (cp < limit && *cp == '[')
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cp++;
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else if (delim)
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return 0;
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ret = in6_pton(cp, limit - cp, (u8 *)&addr->ip6, -1, &end);
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if (ret == 0)
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return 0;
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if (end < limit && *end == ']')
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end++;
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else if (delim)
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return 0;
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break;
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default:
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BUG();
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}
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if (endp)
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*endp = end;
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return 1;
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}
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/* skip ip address. returns its length. */
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static int epaddr_len(const struct nf_conn *ct, const char *dptr,
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const char *limit, int *shift)
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{
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union nf_inet_addr addr;
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const char *aux = dptr;
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if (!sip_parse_addr(ct, dptr, &dptr, &addr, limit, true)) {
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pr_debug("ip: %s parse failed.!\n", dptr);
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return 0;
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}
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/* Port number */
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if (*dptr == ':') {
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dptr++;
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dptr += digits_len(ct, dptr, limit, shift);
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}
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return dptr - aux;
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}
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/* get address length, skiping user info. */
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static int skp_epaddr_len(const struct nf_conn *ct, const char *dptr,
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const char *limit, int *shift)
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{
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const char *start = dptr;
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int s = *shift;
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/* Search for @, but stop at the end of the line.
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* We are inside a sip: URI, so we don't need to worry about
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* continuation lines. */
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while (dptr < limit &&
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*dptr != '@' && *dptr != '\r' && *dptr != '\n') {
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(*shift)++;
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dptr++;
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}
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if (dptr < limit && *dptr == '@') {
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dptr++;
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(*shift)++;
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} else {
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dptr = start;
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*shift = s;
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}
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return epaddr_len(ct, dptr, limit, shift);
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}
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/* Parse a SIP request line of the form:
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*
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* Request-Line = Method SP Request-URI SP SIP-Version CRLF
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*
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* and return the offset and length of the address contained in the Request-URI.
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*/
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int ct_sip_parse_request(const struct nf_conn *ct,
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const char *dptr, unsigned int datalen,
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unsigned int *matchoff, unsigned int *matchlen,
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union nf_inet_addr *addr, __be16 *port)
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{
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const char *start = dptr, *limit = dptr + datalen, *end;
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unsigned int mlen;
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unsigned int p;
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int shift = 0;
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/* Skip method and following whitespace */
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mlen = string_len(ct, dptr, limit, NULL);
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if (!mlen)
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return 0;
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dptr += mlen;
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if (++dptr >= limit)
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return 0;
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/* Find SIP URI */
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for (; dptr < limit - strlen("sip:"); dptr++) {
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if (*dptr == '\r' || *dptr == '\n')
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return -1;
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if (strncasecmp(dptr, "sip:", strlen("sip:")) == 0) {
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dptr += strlen("sip:");
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break;
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}
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}
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if (!skp_epaddr_len(ct, dptr, limit, &shift))
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return 0;
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dptr += shift;
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if (!sip_parse_addr(ct, dptr, &end, addr, limit, true))
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return -1;
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if (end < limit && *end == ':') {
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end++;
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p = simple_strtoul(end, (char **)&end, 10);
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if (p < 1024 || p > 65535)
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return -1;
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*port = htons(p);
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} else
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*port = htons(SIP_PORT);
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if (end == dptr)
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return 0;
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*matchoff = dptr - start;
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*matchlen = end - dptr;
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return 1;
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}
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EXPORT_SYMBOL_GPL(ct_sip_parse_request);
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/* SIP header parsing: SIP headers are located at the beginning of a line, but
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* may span several lines, in which case the continuation lines begin with a
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* whitespace character. RFC 2543 allows lines to be terminated with CR, LF or
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* CRLF, RFC 3261 allows only CRLF, we support both.
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*
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* Headers are followed by (optionally) whitespace, a colon, again (optionally)
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* whitespace and the values. Whitespace in this context means any amount of
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* tabs, spaces and continuation lines, which are treated as a single whitespace
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* character.
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*
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* Some headers may appear multiple times. A comma separated list of values is
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* equivalent to multiple headers.
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*/
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static const struct sip_header ct_sip_hdrs[] = {
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[SIP_HDR_CSEQ] = SIP_HDR("CSeq", NULL, NULL, digits_len),
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[SIP_HDR_FROM] = SIP_HDR("From", "f", "sip:", skp_epaddr_len),
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[SIP_HDR_TO] = SIP_HDR("To", "t", "sip:", skp_epaddr_len),
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[SIP_HDR_CONTACT] = SIP_HDR("Contact", "m", "sip:", skp_epaddr_len),
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[SIP_HDR_VIA_UDP] = SIP_HDR("Via", "v", "UDP ", epaddr_len),
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[SIP_HDR_VIA_TCP] = SIP_HDR("Via", "v", "TCP ", epaddr_len),
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[SIP_HDR_EXPIRES] = SIP_HDR("Expires", NULL, NULL, digits_len),
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[SIP_HDR_CONTENT_LENGTH] = SIP_HDR("Content-Length", "l", NULL, digits_len),
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[SIP_HDR_CALL_ID] = SIP_HDR("Call-Id", "i", NULL, callid_len),
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};
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static const char *sip_follow_continuation(const char *dptr, const char *limit)
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{
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/* Walk past newline */
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if (++dptr >= limit)
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return NULL;
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/* Skip '\n' in CR LF */
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if (*(dptr - 1) == '\r' && *dptr == '\n') {
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if (++dptr >= limit)
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return NULL;
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}
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/* Continuation line? */
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if (*dptr != ' ' && *dptr != '\t')
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return NULL;
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/* skip leading whitespace */
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for (; dptr < limit; dptr++) {
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if (*dptr != ' ' && *dptr != '\t')
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break;
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}
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return dptr;
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}
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static const char *sip_skip_whitespace(const char *dptr, const char *limit)
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{
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for (; dptr < limit; dptr++) {
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if (*dptr == ' ' || *dptr == '\t')
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continue;
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if (*dptr != '\r' && *dptr != '\n')
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break;
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dptr = sip_follow_continuation(dptr, limit);
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break;
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}
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return dptr;
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}
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/* Search within a SIP header value, dealing with continuation lines */
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static const char *ct_sip_header_search(const char *dptr, const char *limit,
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const char *needle, unsigned int len)
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{
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for (limit -= len; dptr < limit; dptr++) {
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if (*dptr == '\r' || *dptr == '\n') {
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dptr = sip_follow_continuation(dptr, limit);
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if (dptr == NULL)
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break;
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continue;
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}
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if (strncasecmp(dptr, needle, len) == 0)
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return dptr;
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}
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return NULL;
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}
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int ct_sip_get_header(const struct nf_conn *ct, const char *dptr,
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unsigned int dataoff, unsigned int datalen,
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enum sip_header_types type,
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unsigned int *matchoff, unsigned int *matchlen)
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{
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const struct sip_header *hdr = &ct_sip_hdrs[type];
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const char *start = dptr, *limit = dptr + datalen;
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int shift = 0;
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for (dptr += dataoff; dptr < limit; dptr++) {
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/* Find beginning of line */
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if (*dptr != '\r' && *dptr != '\n')
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continue;
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if (++dptr >= limit)
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break;
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if (*(dptr - 1) == '\r' && *dptr == '\n') {
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if (++dptr >= limit)
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break;
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}
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/* Skip continuation lines */
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if (*dptr == ' ' || *dptr == '\t')
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continue;
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/* Find header. Compact headers must be followed by a
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* non-alphabetic character to avoid mismatches. */
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if (limit - dptr >= hdr->len &&
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strncasecmp(dptr, hdr->name, hdr->len) == 0)
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dptr += hdr->len;
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else if (hdr->cname && limit - dptr >= hdr->clen + 1 &&
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strncasecmp(dptr, hdr->cname, hdr->clen) == 0 &&
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!isalpha(*(dptr + hdr->clen)))
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dptr += hdr->clen;
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else
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continue;
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/* Find and skip colon */
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dptr = sip_skip_whitespace(dptr, limit);
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if (dptr == NULL)
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break;
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if (*dptr != ':' || ++dptr >= limit)
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break;
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/* Skip whitespace after colon */
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dptr = sip_skip_whitespace(dptr, limit);
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if (dptr == NULL)
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break;
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*matchoff = dptr - start;
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if (hdr->search) {
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dptr = ct_sip_header_search(dptr, limit, hdr->search,
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hdr->slen);
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if (!dptr)
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return -1;
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dptr += hdr->slen;
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}
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*matchlen = hdr->match_len(ct, dptr, limit, &shift);
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if (!*matchlen)
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return -1;
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*matchoff = dptr - start + shift;
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return 1;
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}
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return 0;
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}
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EXPORT_SYMBOL_GPL(ct_sip_get_header);
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/* Get next header field in a list of comma separated values */
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static int ct_sip_next_header(const struct nf_conn *ct, const char *dptr,
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unsigned int dataoff, unsigned int datalen,
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enum sip_header_types type,
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unsigned int *matchoff, unsigned int *matchlen)
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{
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const struct sip_header *hdr = &ct_sip_hdrs[type];
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const char *start = dptr, *limit = dptr + datalen;
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int shift = 0;
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dptr += dataoff;
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dptr = ct_sip_header_search(dptr, limit, ",", strlen(","));
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if (!dptr)
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return 0;
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dptr = ct_sip_header_search(dptr, limit, hdr->search, hdr->slen);
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if (!dptr)
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return 0;
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dptr += hdr->slen;
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*matchoff = dptr - start;
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*matchlen = hdr->match_len(ct, dptr, limit, &shift);
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if (!*matchlen)
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return -1;
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*matchoff += shift;
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return 1;
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}
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/* Walk through headers until a parsable one is found or no header of the
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* given type is left. */
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static int ct_sip_walk_headers(const struct nf_conn *ct, const char *dptr,
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unsigned int dataoff, unsigned int datalen,
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enum sip_header_types type, int *in_header,
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unsigned int *matchoff, unsigned int *matchlen)
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{
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int ret;
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if (in_header && *in_header) {
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while (1) {
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ret = ct_sip_next_header(ct, dptr, dataoff, datalen,
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type, matchoff, matchlen);
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if (ret > 0)
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return ret;
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if (ret == 0)
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break;
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dataoff = *matchoff;
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}
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*in_header = 0;
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}
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while (1) {
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ret = ct_sip_get_header(ct, dptr, dataoff, datalen,
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type, matchoff, matchlen);
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if (ret > 0)
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break;
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if (ret == 0)
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return ret;
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dataoff = *matchoff;
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}
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if (in_header)
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*in_header = 1;
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return 1;
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}
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/* Locate a SIP header, parse the URI and return the offset and length of
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* the address as well as the address and port themselves. A stream of
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* headers can be parsed by handing in a non-NULL datalen and in_header
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* pointer.
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*/
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int ct_sip_parse_header_uri(const struct nf_conn *ct, const char *dptr,
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unsigned int *dataoff, unsigned int datalen,
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enum sip_header_types type, int *in_header,
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unsigned int *matchoff, unsigned int *matchlen,
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union nf_inet_addr *addr, __be16 *port)
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{
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const char *c, *limit = dptr + datalen;
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unsigned int p;
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int ret;
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ret = ct_sip_walk_headers(ct, dptr, dataoff ? *dataoff : 0, datalen,
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type, in_header, matchoff, matchlen);
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WARN_ON(ret < 0);
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if (ret == 0)
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return ret;
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if (!sip_parse_addr(ct, dptr + *matchoff, &c, addr, limit, true))
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return -1;
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if (*c == ':') {
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c++;
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p = simple_strtoul(c, (char **)&c, 10);
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if (p < 1024 || p > 65535)
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return -1;
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*port = htons(p);
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} else
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*port = htons(SIP_PORT);
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if (dataoff)
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*dataoff = c - dptr;
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return 1;
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}
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EXPORT_SYMBOL_GPL(ct_sip_parse_header_uri);
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static int ct_sip_parse_param(const struct nf_conn *ct, const char *dptr,
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unsigned int dataoff, unsigned int datalen,
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const char *name,
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unsigned int *matchoff, unsigned int *matchlen)
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{
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const char *limit = dptr + datalen;
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const char *start;
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const char *end;
|
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limit = ct_sip_header_search(dptr + dataoff, limit, ",", strlen(","));
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if (!limit)
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limit = dptr + datalen;
|
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start = ct_sip_header_search(dptr + dataoff, limit, name, strlen(name));
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if (!start)
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return 0;
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start += strlen(name);
|
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end = ct_sip_header_search(start, limit, ";", strlen(";"));
|
if (!end)
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end = limit;
|
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*matchoff = start - dptr;
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*matchlen = end - start;
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return 1;
|
}
|
|
/* Parse address from header parameter and return address, offset and length */
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int ct_sip_parse_address_param(const struct nf_conn *ct, const char *dptr,
|
unsigned int dataoff, unsigned int datalen,
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const char *name,
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unsigned int *matchoff, unsigned int *matchlen,
|
union nf_inet_addr *addr, bool delim)
|
{
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const char *limit = dptr + datalen;
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const char *start, *end;
|
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limit = ct_sip_header_search(dptr + dataoff, limit, ",", strlen(","));
|
if (!limit)
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limit = dptr + datalen;
|
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start = ct_sip_header_search(dptr + dataoff, limit, name, strlen(name));
|
if (!start)
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return 0;
|
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start += strlen(name);
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if (!sip_parse_addr(ct, start, &end, addr, limit, delim))
|
return 0;
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*matchoff = start - dptr;
|
*matchlen = end - start;
|
return 1;
|
}
|
EXPORT_SYMBOL_GPL(ct_sip_parse_address_param);
|
|
/* Parse numerical header parameter and return value, offset and length */
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int ct_sip_parse_numerical_param(const struct nf_conn *ct, const char *dptr,
|
unsigned int dataoff, unsigned int datalen,
|
const char *name,
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unsigned int *matchoff, unsigned int *matchlen,
|
unsigned int *val)
|
{
|
const char *limit = dptr + datalen;
|
const char *start;
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char *end;
|
|
limit = ct_sip_header_search(dptr + dataoff, limit, ",", strlen(","));
|
if (!limit)
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limit = dptr + datalen;
|
|
start = ct_sip_header_search(dptr + dataoff, limit, name, strlen(name));
|
if (!start)
|
return 0;
|
|
start += strlen(name);
|
*val = simple_strtoul(start, &end, 0);
|
if (start == end)
|
return 0;
|
if (matchoff && matchlen) {
|
*matchoff = start - dptr;
|
*matchlen = end - start;
|
}
|
return 1;
|
}
|
EXPORT_SYMBOL_GPL(ct_sip_parse_numerical_param);
|
|
static int ct_sip_parse_transport(struct nf_conn *ct, const char *dptr,
|
unsigned int dataoff, unsigned int datalen,
|
u8 *proto)
|
{
|
unsigned int matchoff, matchlen;
|
|
if (ct_sip_parse_param(ct, dptr, dataoff, datalen, "transport=",
|
&matchoff, &matchlen)) {
|
if (!strncasecmp(dptr + matchoff, "TCP", strlen("TCP")))
|
*proto = IPPROTO_TCP;
|
else if (!strncasecmp(dptr + matchoff, "UDP", strlen("UDP")))
|
*proto = IPPROTO_UDP;
|
else
|
return 0;
|
|
if (*proto != nf_ct_protonum(ct))
|
return 0;
|
} else
|
*proto = nf_ct_protonum(ct);
|
|
return 1;
|
}
|
|
static int sdp_parse_addr(const struct nf_conn *ct, const char *cp,
|
const char **endp, union nf_inet_addr *addr,
|
const char *limit)
|
{
|
const char *end;
|
int ret;
|
|
memset(addr, 0, sizeof(*addr));
|
switch (nf_ct_l3num(ct)) {
|
case AF_INET:
|
ret = in4_pton(cp, limit - cp, (u8 *)&addr->ip, -1, &end);
|
break;
|
case AF_INET6:
|
ret = in6_pton(cp, limit - cp, (u8 *)&addr->ip6, -1, &end);
|
break;
|
default:
|
BUG();
|
}
|
|
if (ret == 0)
|
return 0;
|
if (endp)
|
*endp = end;
|
return 1;
|
}
|
|
/* skip ip address. returns its length. */
|
static int sdp_addr_len(const struct nf_conn *ct, const char *dptr,
|
const char *limit, int *shift)
|
{
|
union nf_inet_addr addr;
|
const char *aux = dptr;
|
|
if (!sdp_parse_addr(ct, dptr, &dptr, &addr, limit)) {
|
pr_debug("ip: %s parse failed.!\n", dptr);
|
return 0;
|
}
|
|
return dptr - aux;
|
}
|
|
/* SDP header parsing: a SDP session description contains an ordered set of
|
* headers, starting with a section containing general session parameters,
|
* optionally followed by multiple media descriptions.
|
*
|
* SDP headers always start at the beginning of a line. According to RFC 2327:
|
* "The sequence CRLF (0x0d0a) is used to end a record, although parsers should
|
* be tolerant and also accept records terminated with a single newline
|
* character". We handle both cases.
|
*/
|
static const struct sip_header ct_sdp_hdrs_v4[] = {
|
[SDP_HDR_VERSION] = SDP_HDR("v=", NULL, digits_len),
|
[SDP_HDR_OWNER] = SDP_HDR("o=", "IN IP4 ", sdp_addr_len),
|
[SDP_HDR_CONNECTION] = SDP_HDR("c=", "IN IP4 ", sdp_addr_len),
|
[SDP_HDR_MEDIA] = SDP_HDR("m=", NULL, media_len),
|
};
|
|
static const struct sip_header ct_sdp_hdrs_v6[] = {
|
[SDP_HDR_VERSION] = SDP_HDR("v=", NULL, digits_len),
|
[SDP_HDR_OWNER] = SDP_HDR("o=", "IN IP6 ", sdp_addr_len),
|
[SDP_HDR_CONNECTION] = SDP_HDR("c=", "IN IP6 ", sdp_addr_len),
|
[SDP_HDR_MEDIA] = SDP_HDR("m=", NULL, media_len),
|
};
|
|
/* Linear string search within SDP header values */
|
static const char *ct_sdp_header_search(const char *dptr, const char *limit,
|
const char *needle, unsigned int len)
|
{
|
for (limit -= len; dptr < limit; dptr++) {
|
if (*dptr == '\r' || *dptr == '\n')
|
break;
|
if (strncmp(dptr, needle, len) == 0)
|
return dptr;
|
}
|
return NULL;
|
}
|
|
/* Locate a SDP header (optionally a substring within the header value),
|
* optionally stopping at the first occurrence of the term header, parse
|
* it and return the offset and length of the data we're interested in.
|
*/
|
int ct_sip_get_sdp_header(const struct nf_conn *ct, const char *dptr,
|
unsigned int dataoff, unsigned int datalen,
|
enum sdp_header_types type,
|
enum sdp_header_types term,
|
unsigned int *matchoff, unsigned int *matchlen)
|
{
|
const struct sip_header *hdrs, *hdr, *thdr;
|
const char *start = dptr, *limit = dptr + datalen;
|
int shift = 0;
|
|
hdrs = nf_ct_l3num(ct) == NFPROTO_IPV4 ? ct_sdp_hdrs_v4 : ct_sdp_hdrs_v6;
|
hdr = &hdrs[type];
|
thdr = &hdrs[term];
|
|
for (dptr += dataoff; dptr < limit; dptr++) {
|
/* Find beginning of line */
|
if (*dptr != '\r' && *dptr != '\n')
|
continue;
|
if (++dptr >= limit)
|
break;
|
if (*(dptr - 1) == '\r' && *dptr == '\n') {
|
if (++dptr >= limit)
|
break;
|
}
|
|
if (term != SDP_HDR_UNSPEC &&
|
limit - dptr >= thdr->len &&
|
strncasecmp(dptr, thdr->name, thdr->len) == 0)
|
break;
|
else if (limit - dptr >= hdr->len &&
|
strncasecmp(dptr, hdr->name, hdr->len) == 0)
|
dptr += hdr->len;
|
else
|
continue;
|
|
*matchoff = dptr - start;
|
if (hdr->search) {
|
dptr = ct_sdp_header_search(dptr, limit, hdr->search,
|
hdr->slen);
|
if (!dptr)
|
return -1;
|
dptr += hdr->slen;
|
}
|
|
*matchlen = hdr->match_len(ct, dptr, limit, &shift);
|
if (!*matchlen)
|
return -1;
|
*matchoff = dptr - start + shift;
|
return 1;
|
}
|
return 0;
|
}
|
EXPORT_SYMBOL_GPL(ct_sip_get_sdp_header);
|
|
static int ct_sip_parse_sdp_addr(const struct nf_conn *ct, const char *dptr,
|
unsigned int dataoff, unsigned int datalen,
|
enum sdp_header_types type,
|
enum sdp_header_types term,
|
unsigned int *matchoff, unsigned int *matchlen,
|
union nf_inet_addr *addr)
|
{
|
int ret;
|
|
ret = ct_sip_get_sdp_header(ct, dptr, dataoff, datalen, type, term,
|
matchoff, matchlen);
|
if (ret <= 0)
|
return ret;
|
|
if (!sdp_parse_addr(ct, dptr + *matchoff, NULL, addr,
|
dptr + *matchoff + *matchlen))
|
return -1;
|
return 1;
|
}
|
|
static int refresh_signalling_expectation(struct nf_conn *ct,
|
union nf_inet_addr *addr,
|
u8 proto, __be16 port,
|
unsigned int expires)
|
{
|
struct nf_conn_help *help = nfct_help(ct);
|
struct nf_conntrack_expect *exp;
|
struct hlist_node *next;
|
int found = 0;
|
|
spin_lock_bh(&nf_conntrack_expect_lock);
|
hlist_for_each_entry_safe(exp, next, &help->expectations, lnode) {
|
if (exp->class != SIP_EXPECT_SIGNALLING ||
|
!nf_inet_addr_cmp(&exp->tuple.dst.u3, addr) ||
|
exp->tuple.dst.protonum != proto ||
|
exp->tuple.dst.u.udp.port != port)
|
continue;
|
if (mod_timer_pending(&exp->timeout, jiffies + expires * HZ)) {
|
exp->flags &= ~NF_CT_EXPECT_INACTIVE;
|
found = 1;
|
break;
|
}
|
}
|
spin_unlock_bh(&nf_conntrack_expect_lock);
|
return found;
|
}
|
|
static void flush_expectations(struct nf_conn *ct, bool media)
|
{
|
struct nf_conn_help *help = nfct_help(ct);
|
struct nf_conntrack_expect *exp;
|
struct hlist_node *next;
|
|
spin_lock_bh(&nf_conntrack_expect_lock);
|
hlist_for_each_entry_safe(exp, next, &help->expectations, lnode) {
|
if ((exp->class != SIP_EXPECT_SIGNALLING) ^ media)
|
continue;
|
if (!nf_ct_remove_expect(exp))
|
continue;
|
if (!media)
|
break;
|
}
|
spin_unlock_bh(&nf_conntrack_expect_lock);
|
}
|
|
static int set_expected_rtp_rtcp(struct sk_buff *skb, unsigned int protoff,
|
unsigned int dataoff,
|
const char **dptr, unsigned int *datalen,
|
union nf_inet_addr *daddr, __be16 port,
|
enum sip_expectation_classes class,
|
unsigned int mediaoff, unsigned int medialen)
|
{
|
struct nf_conntrack_expect *exp, *rtp_exp, *rtcp_exp;
|
enum ip_conntrack_info ctinfo;
|
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
|
struct net *net = nf_ct_net(ct);
|
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
|
union nf_inet_addr *saddr;
|
struct nf_conntrack_tuple tuple;
|
int direct_rtp = 0, skip_expect = 0, ret = NF_DROP;
|
u_int16_t base_port;
|
__be16 rtp_port, rtcp_port;
|
const struct nf_nat_sip_hooks *hooks;
|
|
saddr = NULL;
|
if (sip_direct_media) {
|
if (!nf_inet_addr_cmp(daddr, &ct->tuplehash[dir].tuple.src.u3))
|
return NF_ACCEPT;
|
saddr = &ct->tuplehash[!dir].tuple.src.u3;
|
} else if (sip_external_media) {
|
struct net_device *dev = skb_dst(skb)->dev;
|
struct net *net = dev_net(dev);
|
struct flowi fl;
|
struct dst_entry *dst = NULL;
|
|
memset(&fl, 0, sizeof(fl));
|
|
switch (nf_ct_l3num(ct)) {
|
case NFPROTO_IPV4:
|
fl.u.ip4.daddr = daddr->ip;
|
nf_ip_route(net, &dst, &fl, false);
|
break;
|
|
case NFPROTO_IPV6:
|
fl.u.ip6.daddr = daddr->in6;
|
nf_ip6_route(net, &dst, &fl, false);
|
break;
|
}
|
|
/* Don't predict any conntracks when media endpoint is reachable
|
* through the same interface as the signalling peer.
|
*/
|
if (dst) {
|
bool external_media = (dst->dev == dev);
|
|
dst_release(dst);
|
if (external_media)
|
return NF_ACCEPT;
|
}
|
}
|
|
/* We need to check whether the registration exists before attempting
|
* to register it since we can see the same media description multiple
|
* times on different connections in case multiple endpoints receive
|
* the same call.
|
*
|
* RTP optimization: if we find a matching media channel expectation
|
* and both the expectation and this connection are SNATed, we assume
|
* both sides can reach each other directly and use the final
|
* destination address from the expectation. We still need to keep
|
* the NATed expectations for media that might arrive from the
|
* outside, and additionally need to expect the direct RTP stream
|
* in case it passes through us even without NAT.
|
*/
|
memset(&tuple, 0, sizeof(tuple));
|
if (saddr)
|
tuple.src.u3 = *saddr;
|
tuple.src.l3num = nf_ct_l3num(ct);
|
tuple.dst.protonum = IPPROTO_UDP;
|
tuple.dst.u3 = *daddr;
|
tuple.dst.u.udp.port = port;
|
|
do {
|
exp = __nf_ct_expect_find(net, nf_ct_zone(ct), &tuple);
|
|
if (!exp || exp->master == ct ||
|
nfct_help(exp->master)->helper != nfct_help(ct)->helper ||
|
exp->class != class)
|
break;
|
#if IS_ENABLED(CONFIG_NF_NAT)
|
if (!direct_rtp &&
|
(!nf_inet_addr_cmp(&exp->saved_addr, &exp->tuple.dst.u3) ||
|
exp->saved_proto.udp.port != exp->tuple.dst.u.udp.port) &&
|
ct->status & IPS_NAT_MASK) {
|
*daddr = exp->saved_addr;
|
tuple.dst.u3 = exp->saved_addr;
|
tuple.dst.u.udp.port = exp->saved_proto.udp.port;
|
direct_rtp = 1;
|
} else
|
#endif
|
skip_expect = 1;
|
} while (!skip_expect);
|
|
base_port = ntohs(tuple.dst.u.udp.port) & ~1;
|
rtp_port = htons(base_port);
|
rtcp_port = htons(base_port + 1);
|
|
if (direct_rtp) {
|
hooks = rcu_dereference(nf_nat_sip_hooks);
|
if (hooks &&
|
!hooks->sdp_port(skb, protoff, dataoff, dptr, datalen,
|
mediaoff, medialen, ntohs(rtp_port)))
|
goto err1;
|
}
|
|
if (skip_expect)
|
return NF_ACCEPT;
|
|
rtp_exp = nf_ct_expect_alloc(ct);
|
if (rtp_exp == NULL)
|
goto err1;
|
nf_ct_expect_init(rtp_exp, class, nf_ct_l3num(ct), saddr, daddr,
|
IPPROTO_UDP, NULL, &rtp_port);
|
|
rtcp_exp = nf_ct_expect_alloc(ct);
|
if (rtcp_exp == NULL)
|
goto err2;
|
nf_ct_expect_init(rtcp_exp, class, nf_ct_l3num(ct), saddr, daddr,
|
IPPROTO_UDP, NULL, &rtcp_port);
|
|
hooks = rcu_dereference(nf_nat_sip_hooks);
|
if (hooks && ct->status & IPS_NAT_MASK && !direct_rtp)
|
ret = hooks->sdp_media(skb, protoff, dataoff, dptr,
|
datalen, rtp_exp, rtcp_exp,
|
mediaoff, medialen, daddr);
|
else {
|
/* -EALREADY handling works around end-points that send
|
* SDP messages with identical port but different media type,
|
* we pretend expectation was set up.
|
* It also works in the case that SDP messages are sent with
|
* identical expect tuples but for different master conntracks.
|
*/
|
int errp = nf_ct_expect_related(rtp_exp,
|
NF_CT_EXP_F_SKIP_MASTER);
|
|
if (errp == 0 || errp == -EALREADY) {
|
int errcp = nf_ct_expect_related(rtcp_exp,
|
NF_CT_EXP_F_SKIP_MASTER);
|
|
if (errcp == 0 || errcp == -EALREADY)
|
ret = NF_ACCEPT;
|
else if (errp == 0)
|
nf_ct_unexpect_related(rtp_exp);
|
}
|
}
|
nf_ct_expect_put(rtcp_exp);
|
err2:
|
nf_ct_expect_put(rtp_exp);
|
err1:
|
return ret;
|
}
|
|
static const struct sdp_media_type sdp_media_types[] = {
|
SDP_MEDIA_TYPE("audio ", SIP_EXPECT_AUDIO),
|
SDP_MEDIA_TYPE("video ", SIP_EXPECT_VIDEO),
|
SDP_MEDIA_TYPE("image ", SIP_EXPECT_IMAGE),
|
};
|
|
static const struct sdp_media_type *sdp_media_type(const char *dptr,
|
unsigned int matchoff,
|
unsigned int matchlen)
|
{
|
const struct sdp_media_type *t;
|
unsigned int i;
|
|
for (i = 0; i < ARRAY_SIZE(sdp_media_types); i++) {
|
t = &sdp_media_types[i];
|
if (matchlen < t->len ||
|
strncmp(dptr + matchoff, t->name, t->len))
|
continue;
|
return t;
|
}
|
return NULL;
|
}
|
|
static int process_sdp(struct sk_buff *skb, unsigned int protoff,
|
unsigned int dataoff,
|
const char **dptr, unsigned int *datalen,
|
unsigned int cseq)
|
{
|
enum ip_conntrack_info ctinfo;
|
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
|
unsigned int matchoff, matchlen;
|
unsigned int mediaoff, medialen;
|
unsigned int sdpoff;
|
unsigned int caddr_len, maddr_len;
|
unsigned int i;
|
union nf_inet_addr caddr, maddr, rtp_addr;
|
const struct nf_nat_sip_hooks *hooks;
|
unsigned int port;
|
const struct sdp_media_type *t;
|
int ret = NF_ACCEPT;
|
|
hooks = rcu_dereference(nf_nat_sip_hooks);
|
|
/* Find beginning of session description */
|
if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen,
|
SDP_HDR_VERSION, SDP_HDR_UNSPEC,
|
&matchoff, &matchlen) <= 0)
|
return NF_ACCEPT;
|
sdpoff = matchoff;
|
|
/* The connection information is contained in the session description
|
* and/or once per media description. The first media description marks
|
* the end of the session description. */
|
caddr_len = 0;
|
if (ct_sip_parse_sdp_addr(ct, *dptr, sdpoff, *datalen,
|
SDP_HDR_CONNECTION, SDP_HDR_MEDIA,
|
&matchoff, &matchlen, &caddr) > 0)
|
caddr_len = matchlen;
|
|
mediaoff = sdpoff;
|
for (i = 0; i < ARRAY_SIZE(sdp_media_types); ) {
|
if (ct_sip_get_sdp_header(ct, *dptr, mediaoff, *datalen,
|
SDP_HDR_MEDIA, SDP_HDR_UNSPEC,
|
&mediaoff, &medialen) <= 0)
|
break;
|
|
/* Get media type and port number. A media port value of zero
|
* indicates an inactive stream. */
|
t = sdp_media_type(*dptr, mediaoff, medialen);
|
if (!t) {
|
mediaoff += medialen;
|
continue;
|
}
|
mediaoff += t->len;
|
medialen -= t->len;
|
|
port = simple_strtoul(*dptr + mediaoff, NULL, 10);
|
if (port == 0)
|
continue;
|
if (port < 1024 || port > 65535) {
|
nf_ct_helper_log(skb, ct, "wrong port %u", port);
|
return NF_DROP;
|
}
|
|
/* The media description overrides the session description. */
|
maddr_len = 0;
|
if (ct_sip_parse_sdp_addr(ct, *dptr, mediaoff, *datalen,
|
SDP_HDR_CONNECTION, SDP_HDR_MEDIA,
|
&matchoff, &matchlen, &maddr) > 0) {
|
maddr_len = matchlen;
|
memcpy(&rtp_addr, &maddr, sizeof(rtp_addr));
|
} else if (caddr_len)
|
memcpy(&rtp_addr, &caddr, sizeof(rtp_addr));
|
else {
|
nf_ct_helper_log(skb, ct, "cannot parse SDP message");
|
return NF_DROP;
|
}
|
|
ret = set_expected_rtp_rtcp(skb, protoff, dataoff,
|
dptr, datalen,
|
&rtp_addr, htons(port), t->class,
|
mediaoff, medialen);
|
if (ret != NF_ACCEPT) {
|
nf_ct_helper_log(skb, ct,
|
"cannot add expectation for voice");
|
return ret;
|
}
|
|
/* Update media connection address if present */
|
if (maddr_len && hooks && ct->status & IPS_NAT_MASK) {
|
ret = hooks->sdp_addr(skb, protoff, dataoff,
|
dptr, datalen, mediaoff,
|
SDP_HDR_CONNECTION,
|
SDP_HDR_MEDIA,
|
&rtp_addr);
|
if (ret != NF_ACCEPT) {
|
nf_ct_helper_log(skb, ct, "cannot mangle SDP");
|
return ret;
|
}
|
}
|
i++;
|
}
|
|
/* Update session connection and owner addresses */
|
hooks = rcu_dereference(nf_nat_sip_hooks);
|
if (hooks && ct->status & IPS_NAT_MASK)
|
ret = hooks->sdp_session(skb, protoff, dataoff,
|
dptr, datalen, sdpoff,
|
&rtp_addr);
|
|
return ret;
|
}
|
static int process_invite_response(struct sk_buff *skb, unsigned int protoff,
|
unsigned int dataoff,
|
const char **dptr, unsigned int *datalen,
|
unsigned int cseq, unsigned int code)
|
{
|
enum ip_conntrack_info ctinfo;
|
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
|
struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
|
|
if ((code >= 100 && code <= 199) ||
|
(code >= 200 && code <= 299))
|
return process_sdp(skb, protoff, dataoff, dptr, datalen, cseq);
|
else if (ct_sip_info->invite_cseq == cseq)
|
flush_expectations(ct, true);
|
return NF_ACCEPT;
|
}
|
|
static int process_update_response(struct sk_buff *skb, unsigned int protoff,
|
unsigned int dataoff,
|
const char **dptr, unsigned int *datalen,
|
unsigned int cseq, unsigned int code)
|
{
|
enum ip_conntrack_info ctinfo;
|
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
|
struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
|
|
if ((code >= 100 && code <= 199) ||
|
(code >= 200 && code <= 299))
|
return process_sdp(skb, protoff, dataoff, dptr, datalen, cseq);
|
else if (ct_sip_info->invite_cseq == cseq)
|
flush_expectations(ct, true);
|
return NF_ACCEPT;
|
}
|
|
static int process_prack_response(struct sk_buff *skb, unsigned int protoff,
|
unsigned int dataoff,
|
const char **dptr, unsigned int *datalen,
|
unsigned int cseq, unsigned int code)
|
{
|
enum ip_conntrack_info ctinfo;
|
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
|
struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
|
|
if ((code >= 100 && code <= 199) ||
|
(code >= 200 && code <= 299))
|
return process_sdp(skb, protoff, dataoff, dptr, datalen, cseq);
|
else if (ct_sip_info->invite_cseq == cseq)
|
flush_expectations(ct, true);
|
return NF_ACCEPT;
|
}
|
|
static int process_invite_request(struct sk_buff *skb, unsigned int protoff,
|
unsigned int dataoff,
|
const char **dptr, unsigned int *datalen,
|
unsigned int cseq)
|
{
|
enum ip_conntrack_info ctinfo;
|
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
|
struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
|
unsigned int ret;
|
|
flush_expectations(ct, true);
|
ret = process_sdp(skb, protoff, dataoff, dptr, datalen, cseq);
|
if (ret == NF_ACCEPT)
|
ct_sip_info->invite_cseq = cseq;
|
return ret;
|
}
|
|
static int process_bye_request(struct sk_buff *skb, unsigned int protoff,
|
unsigned int dataoff,
|
const char **dptr, unsigned int *datalen,
|
unsigned int cseq)
|
{
|
enum ip_conntrack_info ctinfo;
|
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
|
|
flush_expectations(ct, true);
|
return NF_ACCEPT;
|
}
|
|
/* Parse a REGISTER request and create a permanent expectation for incoming
|
* signalling connections. The expectation is marked inactive and is activated
|
* when receiving a response indicating success from the registrar.
|
*/
|
static int process_register_request(struct sk_buff *skb, unsigned int protoff,
|
unsigned int dataoff,
|
const char **dptr, unsigned int *datalen,
|
unsigned int cseq)
|
{
|
enum ip_conntrack_info ctinfo;
|
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
|
struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
|
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
|
unsigned int matchoff, matchlen;
|
struct nf_conntrack_expect *exp;
|
union nf_inet_addr *saddr, daddr;
|
const struct nf_nat_sip_hooks *hooks;
|
__be16 port;
|
u8 proto;
|
unsigned int expires = 0;
|
int ret;
|
|
/* Expected connections can not register again. */
|
if (ct->status & IPS_EXPECTED)
|
return NF_ACCEPT;
|
|
/* We must check the expiration time: a value of zero signals the
|
* registrar to release the binding. We'll remove our expectation
|
* when receiving the new bindings in the response, but we don't
|
* want to create new ones.
|
*
|
* The expiration time may be contained in Expires: header, the
|
* Contact: header parameters or the URI parameters.
|
*/
|
if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_EXPIRES,
|
&matchoff, &matchlen) > 0)
|
expires = simple_strtoul(*dptr + matchoff, NULL, 10);
|
|
ret = ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
|
SIP_HDR_CONTACT, NULL,
|
&matchoff, &matchlen, &daddr, &port);
|
if (ret < 0) {
|
nf_ct_helper_log(skb, ct, "cannot parse contact");
|
return NF_DROP;
|
} else if (ret == 0)
|
return NF_ACCEPT;
|
|
/* We don't support third-party registrations */
|
if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, &daddr))
|
return NF_ACCEPT;
|
|
if (ct_sip_parse_transport(ct, *dptr, matchoff + matchlen, *datalen,
|
&proto) == 0)
|
return NF_ACCEPT;
|
|
if (ct_sip_parse_numerical_param(ct, *dptr,
|
matchoff + matchlen, *datalen,
|
"expires=", NULL, NULL, &expires) < 0) {
|
nf_ct_helper_log(skb, ct, "cannot parse expires");
|
return NF_DROP;
|
}
|
|
if (expires == 0) {
|
ret = NF_ACCEPT;
|
goto store_cseq;
|
}
|
|
exp = nf_ct_expect_alloc(ct);
|
if (!exp) {
|
nf_ct_helper_log(skb, ct, "cannot alloc expectation");
|
return NF_DROP;
|
}
|
|
saddr = NULL;
|
if (sip_direct_signalling)
|
saddr = &ct->tuplehash[!dir].tuple.src.u3;
|
|
nf_ct_expect_init(exp, SIP_EXPECT_SIGNALLING, nf_ct_l3num(ct),
|
saddr, &daddr, proto, NULL, &port);
|
exp->timeout.expires = sip_timeout * HZ;
|
exp->helper = nfct_help(ct)->helper;
|
exp->flags = NF_CT_EXPECT_PERMANENT | NF_CT_EXPECT_INACTIVE;
|
|
hooks = rcu_dereference(nf_nat_sip_hooks);
|
if (hooks && ct->status & IPS_NAT_MASK)
|
ret = hooks->expect(skb, protoff, dataoff, dptr, datalen,
|
exp, matchoff, matchlen);
|
else {
|
if (nf_ct_expect_related(exp, 0) != 0) {
|
nf_ct_helper_log(skb, ct, "cannot add expectation");
|
ret = NF_DROP;
|
} else
|
ret = NF_ACCEPT;
|
}
|
nf_ct_expect_put(exp);
|
|
store_cseq:
|
if (ret == NF_ACCEPT)
|
ct_sip_info->register_cseq = cseq;
|
return ret;
|
}
|
|
static int process_register_response(struct sk_buff *skb, unsigned int protoff,
|
unsigned int dataoff,
|
const char **dptr, unsigned int *datalen,
|
unsigned int cseq, unsigned int code)
|
{
|
enum ip_conntrack_info ctinfo;
|
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
|
struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
|
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
|
union nf_inet_addr addr;
|
__be16 port;
|
u8 proto;
|
unsigned int matchoff, matchlen, coff = 0;
|
unsigned int expires = 0;
|
int in_contact = 0, ret;
|
|
/* According to RFC 3261, "UAs MUST NOT send a new registration until
|
* they have received a final response from the registrar for the
|
* previous one or the previous REGISTER request has timed out".
|
*
|
* However, some servers fail to detect retransmissions and send late
|
* responses, so we store the sequence number of the last valid
|
* request and compare it here.
|
*/
|
if (ct_sip_info->register_cseq != cseq)
|
return NF_ACCEPT;
|
|
if (code >= 100 && code <= 199)
|
return NF_ACCEPT;
|
if (code < 200 || code > 299)
|
goto flush;
|
|
if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_EXPIRES,
|
&matchoff, &matchlen) > 0)
|
expires = simple_strtoul(*dptr + matchoff, NULL, 10);
|
|
while (1) {
|
unsigned int c_expires = expires;
|
|
ret = ct_sip_parse_header_uri(ct, *dptr, &coff, *datalen,
|
SIP_HDR_CONTACT, &in_contact,
|
&matchoff, &matchlen,
|
&addr, &port);
|
if (ret < 0) {
|
nf_ct_helper_log(skb, ct, "cannot parse contact");
|
return NF_DROP;
|
} else if (ret == 0)
|
break;
|
|
/* We don't support third-party registrations */
|
if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3, &addr))
|
continue;
|
|
if (ct_sip_parse_transport(ct, *dptr, matchoff + matchlen,
|
*datalen, &proto) == 0)
|
continue;
|
|
ret = ct_sip_parse_numerical_param(ct, *dptr,
|
matchoff + matchlen,
|
*datalen, "expires=",
|
NULL, NULL, &c_expires);
|
if (ret < 0) {
|
nf_ct_helper_log(skb, ct, "cannot parse expires");
|
return NF_DROP;
|
}
|
if (c_expires == 0)
|
break;
|
if (refresh_signalling_expectation(ct, &addr, proto, port,
|
c_expires))
|
return NF_ACCEPT;
|
}
|
|
flush:
|
flush_expectations(ct, false);
|
return NF_ACCEPT;
|
}
|
|
static const struct sip_handler sip_handlers[] = {
|
SIP_HANDLER("INVITE", process_invite_request, process_invite_response),
|
SIP_HANDLER("UPDATE", process_sdp, process_update_response),
|
SIP_HANDLER("ACK", process_sdp, NULL),
|
SIP_HANDLER("PRACK", process_sdp, process_prack_response),
|
SIP_HANDLER("BYE", process_bye_request, NULL),
|
SIP_HANDLER("REGISTER", process_register_request, process_register_response),
|
};
|
|
static int process_sip_response(struct sk_buff *skb, unsigned int protoff,
|
unsigned int dataoff,
|
const char **dptr, unsigned int *datalen)
|
{
|
enum ip_conntrack_info ctinfo;
|
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
|
unsigned int matchoff, matchlen, matchend;
|
unsigned int code, cseq, i;
|
|
if (*datalen < strlen("SIP/2.0 200"))
|
return NF_ACCEPT;
|
code = simple_strtoul(*dptr + strlen("SIP/2.0 "), NULL, 10);
|
if (!code) {
|
nf_ct_helper_log(skb, ct, "cannot get code");
|
return NF_DROP;
|
}
|
|
if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CSEQ,
|
&matchoff, &matchlen) <= 0) {
|
nf_ct_helper_log(skb, ct, "cannot parse cseq");
|
return NF_DROP;
|
}
|
cseq = simple_strtoul(*dptr + matchoff, NULL, 10);
|
if (!cseq && *(*dptr + matchoff) != '0') {
|
nf_ct_helper_log(skb, ct, "cannot get cseq");
|
return NF_DROP;
|
}
|
matchend = matchoff + matchlen + 1;
|
|
for (i = 0; i < ARRAY_SIZE(sip_handlers); i++) {
|
const struct sip_handler *handler;
|
|
handler = &sip_handlers[i];
|
if (handler->response == NULL)
|
continue;
|
if (*datalen < matchend + handler->len ||
|
strncasecmp(*dptr + matchend, handler->method, handler->len))
|
continue;
|
return handler->response(skb, protoff, dataoff, dptr, datalen,
|
cseq, code);
|
}
|
return NF_ACCEPT;
|
}
|
|
static int process_sip_request(struct sk_buff *skb, unsigned int protoff,
|
unsigned int dataoff,
|
const char **dptr, unsigned int *datalen)
|
{
|
enum ip_conntrack_info ctinfo;
|
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
|
struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
|
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
|
unsigned int matchoff, matchlen;
|
unsigned int cseq, i;
|
union nf_inet_addr addr;
|
__be16 port;
|
|
/* Many Cisco IP phones use a high source port for SIP requests, but
|
* listen for the response on port 5060. If we are the local
|
* router for one of these phones, save the port number from the
|
* Via: header so that nf_nat_sip can redirect the responses to
|
* the correct port.
|
*/
|
if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
|
SIP_HDR_VIA_UDP, NULL, &matchoff,
|
&matchlen, &addr, &port) > 0 &&
|
port != ct->tuplehash[dir].tuple.src.u.udp.port &&
|
nf_inet_addr_cmp(&addr, &ct->tuplehash[dir].tuple.src.u3))
|
ct_sip_info->forced_dport = port;
|
|
for (i = 0; i < ARRAY_SIZE(sip_handlers); i++) {
|
const struct sip_handler *handler;
|
|
handler = &sip_handlers[i];
|
if (handler->request == NULL)
|
continue;
|
if (*datalen < handler->len + 2 ||
|
strncasecmp(*dptr, handler->method, handler->len))
|
continue;
|
if ((*dptr)[handler->len] != ' ' ||
|
!isalpha((*dptr)[handler->len+1]))
|
continue;
|
|
if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CSEQ,
|
&matchoff, &matchlen) <= 0) {
|
nf_ct_helper_log(skb, ct, "cannot parse cseq");
|
return NF_DROP;
|
}
|
cseq = simple_strtoul(*dptr + matchoff, NULL, 10);
|
if (!cseq && *(*dptr + matchoff) != '0') {
|
nf_ct_helper_log(skb, ct, "cannot get cseq");
|
return NF_DROP;
|
}
|
|
return handler->request(skb, protoff, dataoff, dptr, datalen,
|
cseq);
|
}
|
return NF_ACCEPT;
|
}
|
|
static int process_sip_msg(struct sk_buff *skb, struct nf_conn *ct,
|
unsigned int protoff, unsigned int dataoff,
|
const char **dptr, unsigned int *datalen)
|
{
|
const struct nf_nat_sip_hooks *hooks;
|
int ret;
|
|
if (strncasecmp(*dptr, "SIP/2.0 ", strlen("SIP/2.0 ")) != 0)
|
ret = process_sip_request(skb, protoff, dataoff, dptr, datalen);
|
else
|
ret = process_sip_response(skb, protoff, dataoff, dptr, datalen);
|
|
if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) {
|
hooks = rcu_dereference(nf_nat_sip_hooks);
|
if (hooks && !hooks->msg(skb, protoff, dataoff,
|
dptr, datalen)) {
|
nf_ct_helper_log(skb, ct, "cannot NAT SIP message");
|
ret = NF_DROP;
|
}
|
}
|
|
return ret;
|
}
|
|
static int sip_help_tcp(struct sk_buff *skb, unsigned int protoff,
|
struct nf_conn *ct, enum ip_conntrack_info ctinfo)
|
{
|
struct tcphdr *th, _tcph;
|
unsigned int dataoff, datalen;
|
unsigned int matchoff, matchlen, clen;
|
unsigned int msglen, origlen;
|
const char *dptr, *end;
|
s16 diff, tdiff = 0;
|
int ret = NF_ACCEPT;
|
bool term;
|
|
if (ctinfo != IP_CT_ESTABLISHED &&
|
ctinfo != IP_CT_ESTABLISHED_REPLY)
|
return NF_ACCEPT;
|
|
/* No Data ? */
|
th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
|
if (th == NULL)
|
return NF_ACCEPT;
|
dataoff = protoff + th->doff * 4;
|
if (dataoff >= skb->len)
|
return NF_ACCEPT;
|
|
nf_ct_refresh(ct, skb, sip_timeout * HZ);
|
|
if (unlikely(skb_linearize(skb)))
|
return NF_DROP;
|
|
dptr = skb->data + dataoff;
|
datalen = skb->len - dataoff;
|
if (datalen < strlen("SIP/2.0 200"))
|
return NF_ACCEPT;
|
|
while (1) {
|
if (ct_sip_get_header(ct, dptr, 0, datalen,
|
SIP_HDR_CONTENT_LENGTH,
|
&matchoff, &matchlen) <= 0)
|
break;
|
|
clen = simple_strtoul(dptr + matchoff, (char **)&end, 10);
|
if (dptr + matchoff == end)
|
break;
|
|
term = false;
|
for (; end + strlen("\r\n\r\n") <= dptr + datalen; end++) {
|
if (end[0] == '\r' && end[1] == '\n' &&
|
end[2] == '\r' && end[3] == '\n') {
|
term = true;
|
break;
|
}
|
}
|
if (!term)
|
break;
|
end += strlen("\r\n\r\n") + clen;
|
|
msglen = origlen = end - dptr;
|
if (msglen > datalen)
|
return NF_ACCEPT;
|
|
ret = process_sip_msg(skb, ct, protoff, dataoff,
|
&dptr, &msglen);
|
/* process_sip_* functions report why this packet is dropped */
|
if (ret != NF_ACCEPT)
|
break;
|
diff = msglen - origlen;
|
tdiff += diff;
|
|
dataoff += msglen;
|
dptr += msglen;
|
datalen = datalen + diff - msglen;
|
}
|
|
if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) {
|
const struct nf_nat_sip_hooks *hooks;
|
|
hooks = rcu_dereference(nf_nat_sip_hooks);
|
if (hooks)
|
hooks->seq_adjust(skb, protoff, tdiff);
|
}
|
|
return ret;
|
}
|
|
static int sip_help_udp(struct sk_buff *skb, unsigned int protoff,
|
struct nf_conn *ct, enum ip_conntrack_info ctinfo)
|
{
|
unsigned int dataoff, datalen;
|
const char *dptr;
|
|
/* No Data ? */
|
dataoff = protoff + sizeof(struct udphdr);
|
if (dataoff >= skb->len)
|
return NF_ACCEPT;
|
|
nf_ct_refresh(ct, skb, sip_timeout * HZ);
|
|
if (unlikely(skb_linearize(skb)))
|
return NF_DROP;
|
|
dptr = skb->data + dataoff;
|
datalen = skb->len - dataoff;
|
if (datalen < strlen("SIP/2.0 200"))
|
return NF_ACCEPT;
|
|
return process_sip_msg(skb, ct, protoff, dataoff, &dptr, &datalen);
|
}
|
|
static struct nf_conntrack_helper sip[MAX_PORTS * 4] __read_mostly;
|
|
static const struct nf_conntrack_expect_policy sip_exp_policy[SIP_EXPECT_MAX + 1] = {
|
[SIP_EXPECT_SIGNALLING] = {
|
.name = "signalling",
|
.max_expected = 1,
|
.timeout = 3 * 60,
|
},
|
[SIP_EXPECT_AUDIO] = {
|
.name = "audio",
|
.max_expected = 2 * IP_CT_DIR_MAX,
|
.timeout = 3 * 60,
|
},
|
[SIP_EXPECT_VIDEO] = {
|
.name = "video",
|
.max_expected = 2 * IP_CT_DIR_MAX,
|
.timeout = 3 * 60,
|
},
|
[SIP_EXPECT_IMAGE] = {
|
.name = "image",
|
.max_expected = IP_CT_DIR_MAX,
|
.timeout = 3 * 60,
|
},
|
};
|
|
static void __exit nf_conntrack_sip_fini(void)
|
{
|
nf_conntrack_helpers_unregister(sip, ports_c * 4);
|
}
|
|
static int __init nf_conntrack_sip_init(void)
|
{
|
int i, ret;
|
|
NF_CT_HELPER_BUILD_BUG_ON(sizeof(struct nf_ct_sip_master));
|
|
if (ports_c == 0)
|
ports[ports_c++] = SIP_PORT;
|
|
for (i = 0; i < ports_c; i++) {
|
nf_ct_helper_init(&sip[4 * i], AF_INET, IPPROTO_UDP,
|
HELPER_NAME, SIP_PORT, ports[i], i,
|
sip_exp_policy, SIP_EXPECT_MAX, sip_help_udp,
|
NULL, THIS_MODULE);
|
nf_ct_helper_init(&sip[4 * i + 1], AF_INET, IPPROTO_TCP,
|
HELPER_NAME, SIP_PORT, ports[i], i,
|
sip_exp_policy, SIP_EXPECT_MAX, sip_help_tcp,
|
NULL, THIS_MODULE);
|
nf_ct_helper_init(&sip[4 * i + 2], AF_INET6, IPPROTO_UDP,
|
HELPER_NAME, SIP_PORT, ports[i], i,
|
sip_exp_policy, SIP_EXPECT_MAX, sip_help_udp,
|
NULL, THIS_MODULE);
|
nf_ct_helper_init(&sip[4 * i + 3], AF_INET6, IPPROTO_TCP,
|
HELPER_NAME, SIP_PORT, ports[i], i,
|
sip_exp_policy, SIP_EXPECT_MAX, sip_help_tcp,
|
NULL, THIS_MODULE);
|
}
|
|
ret = nf_conntrack_helpers_register(sip, ports_c * 4);
|
if (ret < 0) {
|
pr_err("failed to register helpers\n");
|
return ret;
|
}
|
return 0;
|
}
|
|
module_init(nf_conntrack_sip_init);
|
module_exit(nf_conntrack_sip_fini);
|
