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https://github.com/Waujito/youtubeUnblock.git
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Add distinct fragmentation strategies
Fix ip4_frag, implement no fragmentation strategy. Related to #24
This commit is contained in:
Vadim Vetrov
parent
4793f537de
commit
be40bc91e7
149
youtubeUnblock.c
149
youtubeUnblock.c
@ -27,8 +27,17 @@
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#define USE_GSO
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#endif
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#ifndef USE_IP_FRAGMENTATION
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#define USE_TCP_SEGMENTATION
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#define FRAG_STRAT_TCP 0
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#define FRAG_STRAT_IP 1
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#define FRAG_STRAT_NONE 2
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#define FRAGMENTATION_STRATEGY FRAG_STRAT_TCP
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#if FRAGMENTATION_STRATEGY == FRAG_STRAT_TCP
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#define USE_TCP_SEGMENTATION
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#elif FRAGMENTATION_STRATEGY == FRAG_STRAT_IP
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#define USE_IP_FRAGMENTATION
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#elif FRAGMENTATION_STRATEGY == FRAG_STRAT_NONE
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#endif
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#define RAWSOCKET_MARK (1 << 15)
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@ -173,12 +182,17 @@ static int ipv4_frag(struct pkt_buff *pktb, size_t payload_offset,
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uint8_t buff2[MNL_SOCKET_BUFFER_SIZE];
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struct iphdr *hdr = nfq_ip_get_hdr(pktb);
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if (hdr == NULL) {
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errno = EINVAL;
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return -1;
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}
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size_t hdr_len = hdr->ihl * 4;
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uint8_t *payload = pktb_data(pktb) + hdr_len;
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size_t plen = pktb_len(pktb) - hdr_len;
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if (hdr == NULL || payload == NULL || plen <= payload_offset) {
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if (payload == NULL || plen <= payload_offset) {
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errno = EINVAL;
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return -1;
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}
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@ -255,15 +269,25 @@ static int tcp4_frag(struct pkt_buff *pktb, size_t payload_offset,
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struct iphdr *hdr = nfq_ip_get_hdr(pktb);
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size_t hdr_len = hdr->ihl * 4;
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if (hdr == NULL) {
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errno = EINVAL;
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perror("tcp4_frag: nfq_ip_get_hdr is null\n");
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errno = EINVAL;
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return -1;
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}
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if (hdr->protocol != IPPROTO_TCP || !(ntohs(hdr->frag_off) & IP_DF)) {
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perror("tcp4_frag: proto is tcp or request is fragmented");
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if (hdr->protocol != IPPROTO_TCP) {
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errno = EINVAL;
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perror("tcp4_frag: proto is not tcp");
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errno = EINVAL;
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return -1;
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}
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if (!(ntohs(hdr->frag_off) & IP_DF)) {
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errno = EINVAL;
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perror("tcp4_frag: request is ip-fragmented");
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fprintf(stderr, "tcp4_frag: frag_off: %04x\n", ntohs(hdr->frag_off));
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errno = EINVAL;
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return -1;
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}
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if (nfq_ip_set_transport_header(pktb, hdr)) {
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perror("tcp4_frag: ip_set_transport_header");
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@ -274,6 +298,7 @@ static int tcp4_frag(struct pkt_buff *pktb, size_t payload_offset,
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struct tcphdr *tcph = nfq_tcp_get_hdr(pktb);
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size_t tcph_len = tcph->doff * 4;
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if (tcph == NULL) {
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errno = EINVAL;
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perror("tcp4_frag: tcph is NULL");
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errno = EINVAL;
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return -1;
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@ -283,6 +308,7 @@ static int tcp4_frag(struct pkt_buff *pktb, size_t payload_offset,
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size_t plen = nfq_tcp_get_payload_len(tcph, pktb);
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if (payload == NULL || plen <= payload_offset) {
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errno = EINVAL;
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perror("tcp4_frag: payload is too small or NULL");
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errno = EINVAL;
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return -1;
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@ -352,13 +378,18 @@ static int send_raw_socket(struct pkt_buff *pktb) {
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struct pkt_buff *buff1;
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struct pkt_buff *buff2;
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#ifdef USE_TCP_SEGMENTATION
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#if defined(USE_TCP_SEGMENTATION) || defined(RAWSOCK_TCP_FSTRAT)
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if (tcp4_frag(pktb, AVAILABLE_MTU-128, &buff1, &buff2) < 0)
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return -1;
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#else
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#elif defined(USE_IP_FRAGMENTATION) || defined(RAWSOCK_IP_FSTRAT)
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if (ipv4_frag(pktb, AVAILABLE_MTU-128, &buff1, &buff2) < 0)
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return -1;
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#else
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errno = EINVAL;
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printf("send_raw_socket: Packet is too big but fragmentation is disabled! "
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"Pass -DRAWSOCK_TCP_FSTRAT or -DRAWSOCK_IP_FSTRAT as CFLAGS "
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"To enable it only for raw socket\n");
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return -1;
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#endif
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int sent = 0;
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@ -452,8 +483,6 @@ static int fallback_accept_packet(uint32_t id) {
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const char googlevideo_ending[] = "googlevideo.com";
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const int googlevideo_len = 15;
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#define GOOGLEVIDEO_MARK 0xfc74
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struct verdict {
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int gvideo_hello; /* google video hello packet */
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int sni_offset; /* offset from start of tcp _payload_ */
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@ -718,10 +747,9 @@ static int process_packet(const struct packet_data packet) {
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struct pkt_buff *frag1;
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struct pkt_buff *frag2;
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nfq_nlmsg_verdict_put(verdnlh, packet.id, NF_DROP);
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#ifdef USE_TCP_SEGMENTATION
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int ret = 0;
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#ifdef FAKE_SNI
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struct pkt_buff *fake_sni = gen_fake_sni(ip_header, tcph);
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if (fake_sni == NULL) {
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@ -736,15 +764,13 @@ static int process_packet(const struct packet_data packet) {
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goto fallback;
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}
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#endif
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size_t ipd_offset = vrd.sni_offset;
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size_t mid_offset = ipd_offset + vrd.sni_len / 2;
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struct pkt_buff *pktb = pktb_alloc(
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family,
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packet.payload,
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packet.payload_len,
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0);
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0);
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if (pktb == NULL) {
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perror("pktb_alloc of payload");
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@ -754,22 +780,54 @@ static int process_packet(const struct packet_data packet) {
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goto fallback;
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}
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struct iphdr *piph = nfq_ip_get_hdr(pktb);
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ret = nfq_ip_set_transport_header(pktb, piph);
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struct tcphdr *ptcph = nfq_tcp_get_hdr(pktb);
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if (!piph || ret < 0 || !ptcph) {
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perror("cannot parse pktb");
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goto gv_free;
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}
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nfq_ip_set_checksum(piph);
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nfq_tcp_compute_checksum_ipv4(ptcph, piph);
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#if defined(USE_TCP_SEGMENTATION)
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size_t ipd_offset = vrd.sni_offset;
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size_t mid_offset = ipd_offset + vrd.sni_len / 2;
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if (tcp4_frag(pktb, mid_offset, &frag1, &frag2) < 0) {
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perror("tcp4_frag");
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pktb_free(pktb);
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#ifdef FAKE_SNI
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pktb_free(fake_sni);
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#endif
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goto fallback;
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goto gv_free;
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}
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#elif defined(USE_IP_FRAGMENTATION)
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size_t ipd_offset = ((char *)data - (char *)tcph) + vrd.sni_offset;
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size_t mid_offset = ipd_offset + vrd.sni_len / 2;
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mid_offset += 8 - mid_offset % 8;
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if (ipv4_frag(pktb, mid_offset, &frag1, &frag2) < 0) {
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perror("ipv4_frag");
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goto gv_free;
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}
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#else
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ret = send_raw_socket(pktb);
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if (ret < 0) {
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perror("raw pack send");
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}
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goto gv_free;
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#endif
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ret = send_raw_socket(frag2);
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if (ret < 0) {
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errno = ret;
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perror("raw frags send: frag2");
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pktb_free(frag1);
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goto err;
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goto free_frags;
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}
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#ifdef SEG2_DELAY
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@ -782,45 +840,22 @@ static int process_packet(const struct packet_data packet) {
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#else
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ret = send_raw_socket(frag1);
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if (ret < 0) {
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errno = ret;
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perror("raw frags send: frag1");
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pktb_free(frag1);
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goto err;
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goto free_frags;
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}
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pktb_free(frag1);
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#endif
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err:
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free_frags:
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pktb_free(frag2);
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gv_free:
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pktb_free(pktb);
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#ifdef FAKE_SNI
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pktb_free(fake_sni);
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#endif
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#else
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// TODO: Implement compute of tcp checksum
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// GSO may turn kernel to not compute the tcp checksum.
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// Also it will never be meaningless to ensure the
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// checksum is right.
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// nfq_tcp_compute_checksum_ipv4(tcph, ip_header);
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size_t ipd_offset = ((char *)data - (char *)tcph) + vrd.sni_offset;
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size_t mid_offset = ipd_offset + vrd.sni_len / 2;
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mid_offset += 8 - mid_offset % 8;
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if (ipv4_frag(pktb, mid_offset, &frag1, &frag2) < 0) {
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perror("ipv4_frag");
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goto fallback;
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}
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if ((send_raw_socket(frag1) == -1) || (send_raw_socket(frag2) == -1)) {
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perror("raw frags send");
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}
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pktb_free(frag1);
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pktb_free(frag2);
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#endif
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}
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@ -897,10 +932,12 @@ int main(int argc, const char *argv[])
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exit(EXIT_FAILURE);
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}
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#ifdef USE_TCP_SEGMENTATION
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#if defined(USE_TCP_SEGMENTATION)
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printf("Using TCP segmentation\n");
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#else
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#elif defined(USE_IP_FRAGMENTATION)
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printf("Using IP fragmentation\n");
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#else
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printf("SNI fragmentation is disabled\n");
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#endif
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#ifdef SEG2_DELAY
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