[NETFILTER]: nf_conntrack_sip: parse SIP headers properly
authorPatrick McHardy <kaber@trash.net>
Wed, 26 Mar 2008 03:18:57 +0000 (20:18 -0700)
committerDavid S. Miller <davem@davemloft.net>
Wed, 26 Mar 2008 03:18:57 +0000 (20:18 -0700)
Introduce new function for SIP header parsing that properly deals with
continuation lines and whitespace in headers and use it.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
include/linux/netfilter/nf_conntrack_sip.h
net/ipv4/netfilter/nf_nat_sip.c
net/netfilter/nf_conntrack_sip.c

index 480b26f40ce405e1531fd7892645697aab16cee1..ccc701422963dde4a85f3a8405c5d5086ae56e8c 100644 (file)
@@ -5,14 +5,6 @@
 #define SIP_PORT       5060
 #define SIP_TIMEOUT    3600
 
-enum sip_header_pos {
-       POS_FROM,
-       POS_TO,
-       POS_VIA,
-       POS_CONTACT,
-       POS_CONTENT,
-};
-
 struct sip_header {
        const char      *name;
        const char      *cname;
@@ -36,9 +28,20 @@ struct sip_header {
        .match_len      = (__match),                                    \
 }
 
+#define SIP_HDR(__name, __cname, __search, __match) \
+       __SIP_HDR(__name, __cname, __search, __match)
+
 #define SDP_HDR(__name, __search, __match) \
        __SIP_HDR(__name, NULL, __search, __match)
 
+enum sip_header_types {
+       SIP_HDR_FROM,
+       SIP_HDR_TO,
+       SIP_HDR_CONTACT,
+       SIP_HDR_VIA,
+       SIP_HDR_CONTENT_LENGTH,
+};
+
 enum sdp_header_types {
        SDP_HDR_UNSPEC,
        SDP_HDR_VERSION,
@@ -60,13 +63,10 @@ extern unsigned int (*nf_nat_sdp_hook)(struct sk_buff *skb,
 extern int ct_sip_parse_request(const struct nf_conn *ct,
                                const char *dptr, unsigned int datalen,
                                unsigned int *matchoff, unsigned int *matchlen);
-extern int ct_sip_get_info(const struct nf_conn *ct, const char *dptr,
-                           size_t dlen, unsigned int *matchoff,
-                           unsigned int *matchlen, enum sip_header_pos pos);
-extern int ct_sip_lnlen(const char *line, const char *limit);
-extern const char *ct_sip_search(const char *needle, const char *haystack,
-                                size_t needle_len, size_t haystack_len,
-                                int case_sensitive);
+extern int ct_sip_get_header(const struct nf_conn *ct, const char *dptr,
+                            unsigned int dataoff, unsigned int datalen,
+                            enum sip_header_types type,
+                            unsigned int *matchoff, unsigned int *matchlen);
 
 extern int ct_sip_get_sdp_header(const struct nf_conn *ct, const char *dptr,
                                 unsigned int dataoff, unsigned int datalen,
index 60151b5901a5888f23e6a375fc57622e447fe306..c13e43862361116be922822b0333f9790de106fc 100644 (file)
@@ -108,14 +108,14 @@ static int map_addr(struct sk_buff *skb,
 
 static int map_sip_addr(struct sk_buff *skb,
                        const char **dptr, unsigned int *datalen,
-                       enum sip_header_pos pos, struct addr_map *map)
+                       enum sip_header_types type, struct addr_map *map)
 {
        enum ip_conntrack_info ctinfo;
        struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
        unsigned int matchlen, matchoff;
 
-       if (ct_sip_get_info(ct, *dptr, *datalen, &matchoff, &matchlen,
-                           pos) <= 0)
+       if (ct_sip_get_header(ct, *dptr, 0, *datalen, type,
+                             &matchoff, &matchlen) <= 0)
                return 1;
        return map_addr(skb, dptr, datalen, matchoff, matchlen, map);
 }
@@ -141,10 +141,10 @@ static unsigned int ip_nat_sip(struct sk_buff *skb,
                        return NF_DROP;
        }
 
-       if (!map_sip_addr(skb, dptr, datalen, POS_FROM, &map) ||
-           !map_sip_addr(skb, dptr, datalen, POS_TO, &map) ||
-           !map_sip_addr(skb, dptr, datalen, POS_VIA, &map) ||
-           !map_sip_addr(skb, dptr, datalen, POS_CONTACT, &map))
+       if (!map_sip_addr(skb, dptr, datalen, SIP_HDR_FROM, &map) ||
+           !map_sip_addr(skb, dptr, datalen, SIP_HDR_TO, &map) ||
+           !map_sip_addr(skb, dptr, datalen, SIP_HDR_VIA, &map) ||
+           !map_sip_addr(skb, dptr, datalen, SIP_HDR_CONTACT, &map))
                return NF_DROP;
        return NF_ACCEPT;
 }
@@ -166,8 +166,8 @@ static int mangle_content_len(struct sk_buff *skb,
        c_len = *datalen - matchoff + strlen("v=");
 
        /* Now, update SDP length */
-       if (ct_sip_get_info(ct, *dptr, *datalen, &matchoff, &matchlen,
-                           POS_CONTENT) <= 0)
+       if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CONTENT_LENGTH,
+                             &matchoff, &matchlen) <= 0)
                return 0;
 
        buflen = sprintf(buffer, "%u", c_len);
index bb4396155681c7567a3342abf8d4782e59886ab3..cbc91598acee4759d12d71bb718f35df6077c74a 100644 (file)
@@ -47,109 +47,6 @@ unsigned int (*nf_nat_sdp_hook)(struct sk_buff *skb,
                                struct nf_conntrack_expect *exp) __read_mostly;
 EXPORT_SYMBOL_GPL(nf_nat_sdp_hook);
 
-static int digits_len(const struct nf_conn *, const char *, const char *, int *);
-static int epaddr_len(const struct nf_conn *, const char *, const char *, int *);
-static int skp_digits_len(const struct nf_conn *, const char *, const char *, int *);
-static int skp_epaddr_len(const struct nf_conn *, const char *, const char *, int *);
-
-struct sip_header_nfo {
-       const char      *lname;
-       const char      *sname;
-       const char      *ln_str;
-       size_t          lnlen;
-       size_t          snlen;
-       size_t          ln_strlen;
-       int             case_sensitive;
-       int             (*match_len)(const struct nf_conn *, const char *,
-                                    const char *, int *);
-};
-
-static const struct sip_header_nfo ct_sip_hdrs[] = {
-       [POS_FROM] = {          /* SIP From header */
-               .lname          = "From:",
-               .lnlen          = sizeof("From:") - 1,
-               .sname          = "\r\nf:",
-               .snlen          = sizeof("\r\nf:") - 1,
-               .ln_str         = "sip:",
-               .ln_strlen      = sizeof("sip:") - 1,
-               .match_len      = skp_epaddr_len,
-       },
-       [POS_TO] = {            /* SIP To header */
-               .lname          = "To:",
-               .lnlen          = sizeof("To:") - 1,
-               .sname          = "\r\nt:",
-               .snlen          = sizeof("\r\nt:") - 1,
-               .ln_str         = "sip:",
-               .ln_strlen      = sizeof("sip:") - 1,
-               .match_len      = skp_epaddr_len
-       },
-       [POS_VIA] = {           /* SIP Via header */
-               .lname          = "Via:",
-               .lnlen          = sizeof("Via:") - 1,
-               .sname          = "\r\nv:",
-               .snlen          = sizeof("\r\nv:") - 1, /* rfc3261 "\r\n" */
-               .ln_str         = "UDP ",
-               .ln_strlen      = sizeof("UDP ") - 1,
-               .match_len      = epaddr_len,
-       },
-       [POS_CONTACT] = {       /* SIP Contact header */
-               .lname          = "Contact:",
-               .lnlen          = sizeof("Contact:") - 1,
-               .sname          = "\r\nm:",
-               .snlen          = sizeof("\r\nm:") - 1,
-               .ln_str         = "sip:",
-               .ln_strlen      = sizeof("sip:") - 1,
-               .match_len      = skp_epaddr_len
-       },
-       [POS_CONTENT] = {       /* SIP Content length header */
-               .lname          = "Content-Length:",
-               .lnlen          = sizeof("Content-Length:") - 1,
-               .sname          = "\r\nl:",
-               .snlen          = sizeof("\r\nl:") - 1,
-               .ln_str         = ":",
-               .ln_strlen      = sizeof(":") - 1,
-               .match_len      = skp_digits_len
-       },
-};
-
-/* get line length until first CR or LF seen. */
-int ct_sip_lnlen(const char *line, const char *limit)
-{
-       const char *k = line;
-
-       while ((line < limit) && (*line == '\r' || *line == '\n'))
-               line++;
-
-       while (line < limit) {
-               if (*line == '\r' || *line == '\n')
-                       break;
-               line++;
-       }
-       return line - k;
-}
-EXPORT_SYMBOL_GPL(ct_sip_lnlen);
-
-/* Linear string search, case sensitive. */
-const char *ct_sip_search(const char *needle, const char *haystack,
-                         size_t needle_len, size_t haystack_len,
-                         int case_sensitive)
-{
-       const char *limit = haystack + (haystack_len - needle_len);
-
-       while (haystack < limit) {
-               if (case_sensitive) {
-                       if (strncmp(haystack, needle, needle_len) == 0)
-                               return haystack;
-               } else {
-                       if (strnicmp(haystack, needle, needle_len) == 0)
-                               return haystack;
-               }
-               haystack++;
-       }
-       return NULL;
-}
-EXPORT_SYMBOL_GPL(ct_sip_search);
-
 static int string_len(const struct nf_conn *ct, const char *dptr,
                      const char *limit, int *shift)
 {
@@ -173,16 +70,6 @@ static int digits_len(const struct nf_conn *ct, const char *dptr,
        return len;
 }
 
-/* get digits length, skipping blank spaces. */
-static int skp_digits_len(const struct nf_conn *ct, const char *dptr,
-                         const char *limit, int *shift)
-{
-       for (; dptr < limit && *dptr == ' '; dptr++)
-               (*shift)++;
-
-       return digits_len(ct, dptr, limit, shift);
-}
-
 static int parse_addr(const struct nf_conn *ct, const char *cp,
                       const char **endp, union nf_inet_addr *addr,
                       const char *limit)
@@ -294,50 +181,146 @@ int ct_sip_parse_request(const struct nf_conn *ct,
 }
 EXPORT_SYMBOL_GPL(ct_sip_parse_request);
 
-/* Returns 0 if not found, -1 error parsing. */
-int ct_sip_get_info(const struct nf_conn *ct,
-                   const char *dptr, size_t dlen,
-                   unsigned int *matchoff,
-                   unsigned int *matchlen,
-                   enum sip_header_pos pos)
+/* SIP header parsing: SIP headers are located at the beginning of a line, but
+ * may span several lines, in which case the continuation lines begin with a
+ * whitespace character. RFC 2543 allows lines to be terminated with CR, LF or
+ * CRLF, RFC 3261 allows only CRLF, we support both.
+ *
+ * Headers are followed by (optionally) whitespace, a colon, again (optionally)
+ * whitespace and the values. Whitespace in this context means any amount of
+ * tabs, spaces and continuation lines, which are treated as a single whitespace
+ * character.
+ */
+static const struct sip_header ct_sip_hdrs[] = {
+       [SIP_HDR_FROM]                  = SIP_HDR("From", "f", "sip:", skp_epaddr_len),
+       [SIP_HDR_TO]                    = SIP_HDR("To", "t", "sip:", skp_epaddr_len),
+       [SIP_HDR_CONTACT]               = SIP_HDR("Contact", "m", "sip:", skp_epaddr_len),
+       [SIP_HDR_VIA]                   = SIP_HDR("Via", "v", "UDP ", epaddr_len),
+       [SIP_HDR_CONTENT_LENGTH]        = SIP_HDR("Content-Length", "l", NULL, digits_len),
+};
+
+static const char *sip_follow_continuation(const char *dptr, const char *limit)
 {
-       const struct sip_header_nfo *hnfo = &ct_sip_hdrs[pos];
-       const char *limit, *aux, *k = dptr;
-       int shift = 0;
+       /* Walk past newline */
+       if (++dptr >= limit)
+               return NULL;
+
+       /* Skip '\n' in CR LF */
+       if (*(dptr - 1) == '\r' && *dptr == '\n') {
+               if (++dptr >= limit)
+                       return NULL;
+       }
+
+       /* Continuation line? */
+       if (*dptr != ' ' && *dptr != '\t')
+               return NULL;
+
+       /* skip leading whitespace */
+       for (; dptr < limit; dptr++) {
+               if (*dptr != ' ' && *dptr != '\t')
+                       break;
+       }
+       return dptr;
+}
+
+static const char *sip_skip_whitespace(const char *dptr, const char *limit)
+{
+       for (; dptr < limit; dptr++) {
+               if (*dptr == ' ')
+                       continue;
+               if (*dptr != '\r' && *dptr != '\n')
+                       break;
+               dptr = sip_follow_continuation(dptr, limit);
+               if (dptr == NULL)
+                       return NULL;
+       }
+       return dptr;
+}
 
-       limit = dptr + (dlen - hnfo->lnlen);
+/* Search within a SIP header value, dealing with continuation lines */
+static const char *ct_sip_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') {
+                       dptr = sip_follow_continuation(dptr, limit);
+                       if (dptr == NULL)
+                               break;
+                       continue;
+               }
 
-       while (dptr < limit) {
-               if ((strncmp(dptr, hnfo->lname, hnfo->lnlen) != 0) &&
-                   (hnfo->sname == NULL ||
-                    strncmp(dptr, hnfo->sname, hnfo->snlen) != 0)) {
-                       dptr++;
+               if (strnicmp(dptr, needle, len) == 0)
+                       return dptr;
+       }
+       return NULL;
+}
+
+int ct_sip_get_header(const struct nf_conn *ct, const char *dptr,
+                     unsigned int dataoff, unsigned int datalen,
+                     enum sip_header_types type,
+                     unsigned int *matchoff, unsigned int *matchlen)
+{
+       const struct sip_header *hdr = &ct_sip_hdrs[type];
+       const char *start = dptr, *limit = dptr + datalen;
+       int shift = 0;
+
+       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;
                }
-               aux = ct_sip_search(hnfo->ln_str, dptr, hnfo->ln_strlen,
-                                   ct_sip_lnlen(dptr, limit),
-                                   hnfo->case_sensitive);
-               if (!aux) {
-                       pr_debug("'%s' not found in '%s'.\n", hnfo->ln_str,
-                                hnfo->lname);
-                       return -1;
+
+               /* Skip continuation lines */
+               if (*dptr == ' ' || *dptr == '\t')
+                       continue;
+
+               /* Find header. Compact headers must be followed by a
+                * non-alphabetic character to avoid mismatches. */
+               if (limit - dptr >= hdr->len &&
+                   strnicmp(dptr, hdr->name, hdr->len) == 0)
+                       dptr += hdr->len;
+               else if (hdr->cname && limit - dptr >= hdr->clen + 1 &&
+                        strnicmp(dptr, hdr->cname, hdr->clen) == 0 &&
+                        !isalpha(*(dptr + hdr->clen + 1)))
+                       dptr += hdr->clen;
+               else
+                       continue;
+
+               /* Find and skip colon */
+               dptr = sip_skip_whitespace(dptr, limit);
+               if (dptr == NULL)
+                       break;
+               if (*dptr != ':' || ++dptr >= limit)
+                       break;
+
+               /* Skip whitespace after colon */
+               dptr = sip_skip_whitespace(dptr, limit);
+               if (dptr == NULL)
+                       break;
+
+               *matchoff = dptr - start;
+               if (hdr->search) {
+                       dptr = ct_sip_header_search(dptr, limit, hdr->search,
+                                                   hdr->slen);
+                       if (!dptr)
+                               return -1;
+                       dptr += hdr->slen;
                }
-               aux += hnfo->ln_strlen;
 
-               *matchlen = hnfo->match_len(ct, aux, limit, &shift);
+               *matchlen = hdr->match_len(ct, dptr, limit, &shift);
                if (!*matchlen)
                        return -1;
-
-               *matchoff = (aux - k) + shift;
-
-               pr_debug("%s match succeeded! - len: %u\n", hnfo->lname,
-                        *matchlen);
+               *matchoff = dptr - start + shift;
                return 1;
        }
-       pr_debug("%s header not found.\n", hnfo->lname);
        return 0;
 }
-EXPORT_SYMBOL_GPL(ct_sip_get_info);
+EXPORT_SYMBOL_GPL(ct_sip_get_header);
 
 /* SDP header parsing: a SDP session description contains an ordered set of
  * headers, starting with a section containing general session parameters,