318 lines
11 KiB
C
318 lines
11 KiB
C
#include "socks5.h"
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void socks5_free_ctx(void* elem) {
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struct socks5_ctx* ctx = elem;
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free(ctx->addr);
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free(ctx);
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}
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void socks5_create_dns_client(struct evt_core_ctx* ctx, char* proxy_host, char* proxy_port, char* addr, uint16_t port) {
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struct evt_core_fdinfo fdinfo;
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struct evt_core_cat cat;
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struct socks5_ctx* s5ctx;
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struct evt_core_fdinfo* reg_fdinfo;
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char url[1024];
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// 0. Compute domain length and enforce an upper bound on its size
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size_t domainLength = strlen(addr);
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if (domainLength > 255) {
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fprintf(stderr, "domain is too long\n");
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exit(EXIT_FAILURE);
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}
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// 1. Open connection
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int sock = create_tcp_client (proxy_host, proxy_port);
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if (sock < 0) {
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fprintf(stderr, "Unable to connect to proxy %s:%s\n", proxy_host, proxy_port);
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exit(EXIT_FAILURE);
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}
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// 2. Create fdinfo
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fdinfo.cat = &cat;
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fdinfo.cat->name = "socks5-send-handshake";
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fdinfo.fd = sock;
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fdinfo.other = malloc(sizeof(struct socks5_ctx));
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if (fdinfo.other == NULL) {
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perror("malloc failed");
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exit(EXIT_FAILURE);
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}
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memset(fdinfo.other, 0, sizeof(struct socks5_ctx));
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fdinfo.free_other = socks5_free_ctx;
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sprintf(url, "socks5:send-hs:%s:%d", addr, port);
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fdinfo.url = url;
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// 3. Fill socks5_ctx structures
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s5ctx = fdinfo.other;
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s5ctx->port = port;
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s5ctx->addr = strdup(addr);
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// 3.1 Client handshake to send
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s5ctx->ch.ver = VER_SOCKS5;
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s5ctx->ch.nmethods = 0x01;
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s5ctx->ch.methods[0] = METHOD_NOAUTH;
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s5ctx->ch_size = sizeof(uint8_t) * (2 + s5ctx->ch.nmethods);
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// 3.2 Client request to send
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s5ctx->cr.ver = VER_SOCKS5;
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s5ctx->cr.cmd = CMD_CONNECT;
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s5ctx->cr.rsv = 0x00;
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s5ctx->cr.atyp = ATYP_DOMAINNAME;
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s5ctx->cr.dst_addr_len = domainLength;
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s5ctx->cr.dst_addr = addr;
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s5ctx->cr.port = htons(port);
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// 3.3 Generate client request buffer
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s5ctx->cr_size = 0;
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fill_buffer(&s5ctx->cr_size, s5ctx->cr_buffer, &s5ctx->cr, 5*sizeof(uint8_t));
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fill_buffer(&s5ctx->cr_size, s5ctx->cr_buffer, s5ctx->cr.dst_addr, s5ctx->cr.dst_addr_len*sizeof(char));
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fill_buffer(&s5ctx->cr_size, s5ctx->cr_buffer, &s5ctx->cr.port, sizeof(uint16_t));
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reg_fdinfo = evt_core_add_fd (ctx, &fdinfo);
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}
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int on_socks5_send_handshake(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo) {
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struct socks5_ctx* s5ctx = fdinfo->other;
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size_t written = write(fdinfo->fd, (char*)&s5ctx->ch + s5ctx->ch_cursor, s5ctx->ch_size - s5ctx->ch_cursor);
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if (written == -1 && errno == EAGAIN) return 1;
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if (written < 0) {
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perror("write failed on tcp socket in socks5");
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evt_core_mv_fd2(ctx, fdinfo, "socks5-failed");
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return 1;
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}
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s5ctx->ch_cursor += written;
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if (s5ctx->ch_cursor < s5ctx->ch_size) return 0;
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evt_core_mv_fd2(ctx, fdinfo, "socks5-recv-handshake");
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return 1;
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}
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int on_socks5_recv_handshake(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo) {
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struct socks5_ctx* s5ctx = fdinfo->other;
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int readn = 0;
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readn = read(fdinfo->fd, (char*)&s5ctx->sh + s5ctx->sh_cursor, sizeof(s5ctx->sh) - s5ctx->sh_cursor);
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if (readn == -1 && errno == EAGAIN) return 1;
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if (readn < 0) {
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perror("sock5 handshake failed read");
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evt_core_mv_fd2(ctx, fdinfo, "socks5-failed");
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return 1;
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}
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s5ctx->sh_cursor += readn;
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if (s5ctx->sh_cursor < sizeof(s5ctx->sh)) return 0;
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if (s5ctx->ch.ver != s5ctx->sh.ver || s5ctx->sh.method != s5ctx->ch.methods[0]) {
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fprintf(stderr, "Protocol error: client asks for ver=%d, method=%d and server answers with ver=%d, method=%d\n",
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s5ctx->ch.ver, s5ctx->ch.methods[0], s5ctx->sh.ver, s5ctx->sh.method);
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evt_core_mv_fd2(ctx, fdinfo, "socks5-failed");
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return 1;
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}
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printf("[socks5_server_handshake] fd=%d, ver=%d, method=%d\n", fdinfo->fd, s5ctx->sh.ver, s5ctx->sh.method);
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evt_core_mv_fd2(ctx, fdinfo, "socks5-send-client-req");
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return 1;
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}
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int on_socks5_send_client_req(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo) {
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struct socks5_ctx* s5ctx = fdinfo->other;
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int written = 0;
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written = write(fdinfo->fd, (char*)s5ctx->cr_buffer + s5ctx->cr_cursor, s5ctx->cr_size - s5ctx->cr_cursor);
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if (written == -1 && errno == EAGAIN) return 1;
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if (written < 0) {
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fprintf(stderr, "socks5 send client request failed\n");
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evt_core_mv_fd2 (ctx, fdinfo, "socks5-failed");
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return 1;
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}
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s5ctx->cr_cursor += written;
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if (s5ctx->cr_cursor < s5ctx->cr_size) return 0;
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evt_core_mv_fd2 (ctx, fdinfo, "socks5-recv-server-reply");
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return 1;
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}
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int socks5_server_reply_atyp_ipv4(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo) {
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struct socks5_ctx* s5ctx = fdinfo->other;
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size_t fixed_headers_size = (char*)&s5ctx->sr.bind_addr.ipv4 - (char*)&s5ctx->sr;
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size_t host_size = sizeof(s5ctx->sr.bind_addr.ipv4);
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uint64_t relative_cursor = (s5ctx->sr_cursor - fixed_headers_size);
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int nread = 0;
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nread = read(fdinfo->fd,
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(char*)s5ctx->sr.bind_addr.ipv4 + relative_cursor,
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host_size - relative_cursor);
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if (nread == -1 && errno == EAGAIN) return 1;
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if (nread < 0) {
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perror("write failed on tcp socket in socks5");
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evt_core_mv_fd2(ctx, fdinfo, "socks5-failed");
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return 1;
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}
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s5ctx->sr_cursor += nread;
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if (s5ctx->sr_cursor < fixed_headers_size + host_size) return 0;
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s5ctx->sr_host_read = 1;
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return 0;
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}
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int socks5_server_reply_atyp_ipv6(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo) {
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struct socks5_ctx* s5ctx = fdinfo->other;
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size_t fixed_headers_size = (char*)&s5ctx->sr.bind_addr.ipv6 - (char*)&s5ctx->sr;
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size_t host_size = sizeof(s5ctx->sr.bind_addr.ipv6);
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uint64_t relative_cursor = (s5ctx->sr_cursor - fixed_headers_size);
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int nread = 0;
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nread = read(fdinfo->fd,
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(char*)s5ctx->sr.bind_addr.ipv6 + relative_cursor,
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host_size - relative_cursor);
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if (nread == -1 && errno == EAGAIN) return 1;
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if (nread < 0) {
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perror("write failed on tcp socket in socks5");
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evt_core_mv_fd2(ctx, fdinfo, "socks5-failed");
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return 1;
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}
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s5ctx->sr_cursor += nread;
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if (s5ctx->sr_cursor < fixed_headers_size + host_size) return 0;
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s5ctx->sr_host_read = 1;
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return 0;
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}
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int socks5_server_reply_atyp_dn(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo) {
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struct socks5_ctx* s5ctx = fdinfo->other;
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size_t fixed_headers_size = (char*)&s5ctx->sr.bind_addr.ipv6 - (char*)&s5ctx->sr;
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size_t dn_size_size = sizeof(s5ctx->sr.bind_addr.dns.len);
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uint64_t relative_cursor = 0;
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int nread = 0;
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if (s5ctx->sr_cursor < fixed_headers_size + dn_size_size) {
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relative_cursor = (s5ctx->sr_cursor - fixed_headers_size);
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nread = read(fdinfo->fd, (char*)&s5ctx->sr.bind_addr.dns.len + relative_cursor, dn_size_size - relative_cursor);
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if (nread == -1 && errno == EAGAIN) return 1;
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if (nread < 0) {
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perror("write failed on tcp socket in socks5");
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evt_core_mv_fd2(ctx, fdinfo, "socks5-failed");
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return 1;
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}
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s5ctx->sr_cursor += nread;
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return 0;
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}
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relative_cursor = s5ctx->sr_cursor - fixed_headers_size - sizeof(s5ctx->sr.bind_addr.dns.len);
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nread = read(fdinfo->fd, (char*)&s5ctx->sr.bind_addr.dns.str + relative_cursor, s5ctx->sr.bind_addr.dns.len - relative_cursor);
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if (nread == -1 && errno == EAGAIN) return 1;
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if (nread < 0) {
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perror("write failed on tcp socket in socks5");
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evt_core_mv_fd2(ctx, fdinfo, "socks5-failed");
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return 1;
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}
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s5ctx->sr_cursor += nread;
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if (s5ctx->sr_cursor < fixed_headers_size + dn_size_size + s5ctx->sr.bind_addr.dns.len) return 0;
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s5ctx->sr_host_read = 1;
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return 0;
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}
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size_t socks5_server_reply_size(struct server_reply* sr) {
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size_t fixed_headers_size = (char*)&sr->bind_addr - (char*)sr;
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size_t fixed_tail_size = (char*)(sr + 1) - (char*)&sr->port;
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size_t host_size = 0;
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if (sr->atyp == ATYP_IPV4) {
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host_size = sizeof(sr->bind_addr.ipv4);
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} else if (sr->atyp == ATYP_IPV6) {
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host_size = sizeof(sr->bind_addr.ipv6);
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} else if (sr->atyp == ATYP_DOMAINNAME) {
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host_size = sizeof(sr->bind_addr.dns.len) + sr->bind_addr.dns.len;
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} else {
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fprintf(stderr, "Unsupported ATYP for SOCK5\n");
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exit(EXIT_FAILURE);
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}
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return fixed_headers_size + host_size + fixed_tail_size;
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}
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int on_socks5_recv_server_reply(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo) {
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struct socks5_ctx* s5ctx = fdinfo->other;
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int readn = 0;
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size_t fixed_headers_size = (char*)&s5ctx->sr.bind_addr - (char*)&s5ctx->sr;
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// Read headers
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if (s5ctx->sr_cursor < fixed_headers_size) {
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readn = read(fdinfo->fd, (char*)&s5ctx->sr + s5ctx->sr_cursor, fixed_headers_size - s5ctx->sr_cursor);
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if (readn == -1 && errno == EAGAIN) return 1;
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if (readn < 0) goto move_to_failed;
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s5ctx->sr_cursor += readn;
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return 0; // Needed as we might have not read enough bytes and free us from writing a loop
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}
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// Read host
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if (!s5ctx->sr_host_read) {
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if (s5ctx->sr.atyp == ATYP_IPV4) return socks5_server_reply_atyp_ipv4(ctx, fdinfo);
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else if (s5ctx->sr.atyp == ATYP_IPV6) return socks5_server_reply_atyp_ipv6(ctx, fdinfo);
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else if (s5ctx->sr.atyp == ATYP_DOMAINNAME) return socks5_server_reply_atyp_dn(ctx, fdinfo);
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else goto move_to_failed;
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}
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// Read port
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size_t final_size = socks5_server_reply_size(&s5ctx->sr);
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if (s5ctx->sr_cursor < final_size) {
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size_t relative_cursor = s5ctx->sr_cursor - (final_size - sizeof(s5ctx->sr.port));
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readn = read(fdinfo->fd, (char*)&s5ctx->sr.port + relative_cursor, sizeof(s5ctx->sr.port) - relative_cursor);
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if (readn == -1 && errno == EAGAIN) return 1;
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if (readn < 0) goto move_to_failed;
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s5ctx->sr_cursor += readn;
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return 0; // Needed as we might have not read enough bytes and free us from writing a loop
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}
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// Do some checks
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if (s5ctx->sr.rep > 0x08) goto move_to_failed;
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printf("[socks5_server_reply] fd=%d, ver=%d, rep=%s, atyp=%d, port=%d\n", fdinfo->fd, s5ctx->sr.ver, rep_msg[s5ctx->sr.rep], s5ctx->sr.atyp, s5ctx->sr.port);
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if (s5ctx->sr.rep != SOCKS5_REP_SUCCESS) goto move_to_failed;
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evt_core_mv_fd2 (ctx, fdinfo, "socks5-success");
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return 1;
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move_to_failed:
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evt_core_mv_fd2 (ctx, fdinfo, "socks5-failed");
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return 1;
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}
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int on_socks5_err(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo) {
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evt_core_mv_fd2 (ctx, fdinfo, "socks5-failed");
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return 1;
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}
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void socks5_init(struct evt_core_ctx* ctx) {
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struct evt_core_cat template = {0};
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template.cb = on_socks5_send_handshake;
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template.err_cb = on_socks5_err;
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template.name = "socks5-send-handshake";
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template.flags = EPOLLOUT | EPOLLET;
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evt_core_add_cat (ctx, &template);
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template.cb = on_socks5_recv_handshake;
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template.err_cb = on_socks5_err;
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template.name = "socks5-recv-handshake";
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template.flags = EPOLLIN | EPOLLET;
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evt_core_add_cat (ctx, &template);
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template.cb = on_socks5_send_client_req;
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template.err_cb = on_socks5_err;
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template.name = "socks5-send-client-req";
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template.flags = EPOLLOUT | EPOLLET;
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evt_core_add_cat(ctx, &template);
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template.cb = on_socks5_recv_server_reply;
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template.err_cb = on_socks5_err;
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template.name = "socks5-recv-server-reply";
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template.flags = EPOLLIN | EPOLLET;
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evt_core_add_cat(ctx, &template);
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}
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char* socks5_rep (enum socks5_rep rep) {
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return rep_msg[rep];
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}
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