[libnfc] patch for access remote devices

[mywalkb]

I have a device android where I can't compile kernel and add modules, so I can't add usb serial modules, because the source code are missing.
I'm using the app TCPUART for access to my serial pn532 device with libnfc.
The idea is taken from Proxmark3, so I used the same source code for access to serial device using libnfc.
Is it possible apply this patch to libnfc distribuited in termux-packages? If yes I will make a PR.
I've been testing on my devices for a few weeks now with no issues.
libnfc produces some warnings but they can be ignored

~ $ export LIBNFC_DEVICE="pn532_uart:tcp_127.0.0.1_10000"
~ $ nfc-list
error   libnfc.bus.uart Unable to apply new speed settings.
NFC device: user defined device opened
1 ISO14443A passive target(s) found:
ISO/IEC 14443A (106 kbps) target:
    ATQA (SENS_RES): 00  04
       UID (NFCID1): 0d  58  20  1e
      SAK (SEL_RES): 08

This is the patch:

diff --git a/libnfc/buses/uart.c b/libnfc/buses/uart.c
index deae2d4..aad5695 100644
--- a/libnfc/buses/uart.c
+++ b/libnfc/buses/uart.c
@@ -50,6 +50,10 @@
 #include <termios.h>
 #include <unistd.h>
 #include <stdlib.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <netinet/tcp.h>
+#include <netdb.h>
 
 #include <nfc/nfc.h>
 #include "nfc-internal.h"
@@ -97,6 +101,10 @@ const char *serial_ports_device_radix[] = { "ttyUSB", "ttyS", "ttyACM", "ttyAMA"
 #  define CCLAIMED 0x80000000
 #endif
 
+#ifndef SOL_TCP
+# define SOL_TCP IPPROTO_TCP
+#endif
+
 struct serial_port_unix {
   int                  fd;                     // Serial port file descriptor
   struct termios       termios_backup;         // Terminal info before using the port
@@ -115,6 +123,117 @@ uart_open(const char *pcPortName)
   if (sp == 0)
     return INVALID_SERIAL_PORT;
 
+  if (memcmp(pcPortName, "tcp_", 4) == 0) {
+        struct addrinfo *addr = NULL, *rp;
+        char *addrstr = strdup(pcPortName + 4);
+
+        if (addrstr == NULL) {
+            printf("Error: strdup\n");
+            free(sp);
+            return INVALID_SERIAL_PORT;
+        }
+
+        char *colon = strrchr(addrstr, '_');
+        const char *portstr;
+        if (colon) {
+            portstr = colon + 1;
+            *colon = '\0';
+        } else {
+            portstr = "7901";
+        }
+
+        struct addrinfo info;
+
+        memset(&info, 0, sizeof(info));
+
+        info.ai_socktype = SOCK_STREAM;
+
+        int s = getaddrinfo(addrstr, portstr, &info, &addr);
+        if (s != 0) {
+            printf("Error: getaddrinfo: %s\n", gai_strerror(s));
+            freeaddrinfo(addr);
+            free(addrstr);
+            free(sp);
+            return INVALID_SERIAL_PORT;
+        }
+
+        int sfd;
+        for (rp = addr; rp != NULL; rp = rp->ai_next) {
+            sfd = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
+
+            if (sfd == -1)
+                continue;
+
+            if (connect(sfd, rp->ai_addr, rp->ai_addrlen) != -1)
+                break;
+
+            close(sfd);
+        }
+
+        if (rp == NULL) {               /* No address succeeded */
+            printf("Error: Could not connect\n");
+            freeaddrinfo(addr);
+            free(addrstr);
+            free(sp);
+            return INVALID_SERIAL_PORT;
+        }
+
+        freeaddrinfo(addr);
+        free(addrstr);
+
+        sp->fd = sfd;
+
+        int one = 1;
+        int res = setsockopt(sp->fd, SOL_TCP, TCP_NODELAY, &one, sizeof(one));
+        if (res != 0) {
+            free(sp);
+            return INVALID_SERIAL_PORT;
+        }
+        return sp;
+  }
+
+    // The socket for abstract namespace implement.
+    // Is local socket buffer, not a TCP or any net connection!
+    // so, you can't connect with address like: 127.0.0.1, or any IP
+    // see http://man7.org/linux/man-pages/man7/unix.7.html
+  if (memcmp(pcPortName, "socket_", 7) == 0) {
+        if (strlen(pcPortName) <= 7) {
+            free(sp);
+            return INVALID_SERIAL_PORT;
+        }
+
+        size_t servernameLen = (strlen(pcPortName) - 7) + 1;
+        char serverNameBuf[servernameLen];
+        memset(serverNameBuf, '\0', servernameLen);
+        for (int i = 7, j = 0; j < servernameLen; ++i, ++j) {
+            serverNameBuf[j] = pcPortName[i];
+        }
+        serverNameBuf[servernameLen - 1] = '\0';
+
+        int localsocket, len;
+        struct sockaddr_un remote;
+
+        remote.sun_path[0] = '\0';  // abstract namespace
+        strcpy(remote.sun_path + 1, serverNameBuf);
+        remote.sun_family = AF_LOCAL;
+        int nameLen = strlen(serverNameBuf);
+        len = 1 + nameLen + offsetof(struct sockaddr_un, sun_path);
+
+        if ((localsocket = socket(PF_LOCAL, SOCK_STREAM, 0)) == -1) {
+            free(sp);
+            return INVALID_SERIAL_PORT;
+        }
+
+        if (connect(localsocket, (struct sockaddr *) &remote, len) == -1) {
+            free(sp);
+            return INVALID_SERIAL_PORT;
+        }
+
+        sp->fd = localsocket;
+
+        return sp;
+  }
+
   sp->fd = open(pcPortName, O_RDWR | O_NOCTTY | O_NONBLOCK);
   if (sp->fd == -1) {
     uart_close_ext(sp, false);

[xtkoba]

Beyond our handling. Please submit that patch upstream. Thanks.

[mywalkb]

I can understand you.
This patch is useful only on android and libnfc stopped to process PR, for these 2 reasons I wrote here.
So I will continue to use only for myself and I don't lost my time to make useless PR.