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128 lines
3.3 KiB
128 lines
3.3 KiB
static int extmap_find(const void *key, const void *ele) {
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const uint8_t *k = key, *e = ele;
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if (*k < *e)
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return -1;
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if (*k > *e)
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return 1;
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return 0;
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}
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static bool extmap_has_ext(uint8_t id, struct rtpengine_output *o) {
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uint8_t *const *match = bsearch(&id, o->output.extmap_filter, o->output.num_extmap_filter,
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sizeof(*o->output.extmap_filter), extmap_find);
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return match != NULL;
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}
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static bool apply_extmap_filter_ext(uint8_t id, size_t len, size_t size,
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unsigned char **r, unsigned char **w, unsigned char *end,
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unsigned int *count,
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struct rtpengine_output *o)
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{
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if (*r + size + len > end)
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return false;
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if (extmap_has_ext(id, o)) {
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// retain ext
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if (*r != *w)
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memmove(*w, *r, len + size);
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*w += len + size;
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(*count)++;
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}
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// else: skip over & filter out
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*r += len + size;
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return true;
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}
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static void apply_extmap_filter_finish(unsigned char *r, unsigned char *w, unsigned int count,
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struct sk_buff *skb, struct rtp_parsed *rtp)
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{
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if (r == w)
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return; // everything left as it was
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if (count == 0) {
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// no extensions, remove header and trim packet
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rtp->rtp_header->v_p_x_cc &= ~0x10;
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size_t pull = rtp->payload - (unsigned char *) rtp->ext_hdr;
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memmove(rtp->ext_hdr, rtp->payload, rtp->payload_len);
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rtp->payload = (unsigned char *) rtp->ext_hdr;
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rtp->ext_hdr = NULL;
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rtp->extension_len = 0;
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skb_trim(skb, skb->len - pull);
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return;
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}
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// shift up payload and trim packet
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size_t size = w - rtp->extension;
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size_t padded = (size + 3L) & ~3L;
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memset(w, 0, padded - size);
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rtp->ext_hdr->length = htons(padded / 4);
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size_t pull = rtp->extension_len - padded;
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rtp->extension_len = padded;
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memmove(rtp->payload - pull, rtp->payload, rtp->payload_len);
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rtp->payload -= pull;
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skb_trim(skb, skb->len - pull);
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}
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static void apply_extmap_filter_short(struct sk_buff *skb, struct rtpengine_output *o, struct rtp_parsed *rtp) {
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unsigned char *r = rtp->extension; // reader
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unsigned char *end = r + rtp->extension_len;
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unsigned char *w = r; // writer
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unsigned int count = 0; // non-padding extensions
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// XXX partly shared code
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while (r < end) {
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uint8_t id_len = r[0];
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if (id_len == '\0') {
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// padding
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r++; // don't copy padding to *w
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continue;
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}
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uint8_t id = id_len >> 4;
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uint8_t len = (id_len & 0xf) + 1;
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if (!apply_extmap_filter_ext(id, len, 1, &r, &w, end, &count, o))
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break;
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}
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apply_extmap_filter_finish(r, w, count, skb, rtp);
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}
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static void apply_extmap_filter_long(struct sk_buff *skb, struct rtpengine_output *o, struct rtp_parsed *rtp) {
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unsigned char *r = rtp->extension; // reader
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unsigned char *end = r + rtp->extension_len;
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unsigned char *w = r; // writer
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unsigned int count = 0; // non-padding extensions
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// XXX partly shared code
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while (r < end) {
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uint8_t id = r[0];
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if (id == '\0') {
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// padding
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r++; // don't copy padding to *w
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continue;
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}
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uint8_t len = r[1];
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if (!apply_extmap_filter_ext(id, len, 2, &r, &w, end, &count, o))
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break;
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}
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apply_extmap_filter_finish(r, w, count, skb, rtp);
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}
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static void apply_extmap_filter(struct sk_buff *skb, struct rtpengine_output *o, struct rtp_parsed *rtp) {
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if (!rtp->ext_hdr)
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return;
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if (ntohs(rtp->ext_hdr->undefined) == 0xbede)
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apply_extmap_filter_short(skb, o, rtp);
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else if ((ntohs(rtp->ext_hdr->undefined) & 0xfff0) == 0x0100)
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apply_extmap_filter_long(skb, o, rtp);
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// else: leave untouched
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}
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