source: branches/nameserver/CORE/arb_cs.cxx

// ============================================================= //
//                                                               //
//   File      : arb_cs.cxx                                      //
//   Purpose   : Basics for client/server communication          //
//                                                               //
//   Coded by Ralf Westram (coder@reallysoft.de) in March 2011   //
//   Institute of Microbiology (Technical University Munich)     //
//   http://www.arb-home.de/                                     //
//                                                               //
// ============================================================= //

#include "arb_cs.h"
#include "arb_msg.h"
#include "arb_pattern.h"
#include "arb_string.h"

#include <smartptr.h>

#include <unistd.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/stat.h>
#include <netinet/tcp.h>

// We need one of the below to prevent SIGPIPE on writes to 
// closed socket. For systems that have neither (Solaris),
// we'd need to implement ignoring the signal in the write
// loop (not done). 
#ifndef SO_NOSIGPIPE
#ifndef MSG_NOSIGNAL
#error Neither SO_NOSIGPIPE nor MSG_NOSIGNAL available!
#endif
#endif

static void arb_gethostbyname(const char *name, struct hostent *& he, GB_ERROR& err) {
    he = gethostbyname(name);
    // Note: gethostbyname is marked obsolete.
    // replacement getnameinfo seems less portable atm.

    if (he) {
        err = NULp;
    }
    else {
        err = GBS_global_string("Cannot resolve hostname: '%s' (h_errno=%i='%s')",
                                name, h_errno, hstrerror(h_errno));
    }
}

const char *arb_gethostname() {
    static SmartCharPtr hostname;
    if (hostname.isNull()) {
        char buffer[4096];
        gethostname(buffer, 4095);
        hostname = ARB_strdup(buffer);
    }
    return &*hostname;
}

size_t arb_socket_read(int socket, char* ptr, size_t size) {
    size_t to_read = size;
    while(to_read) {
        ssize_t read_len = read(socket, ptr, to_read);
        if (read_len <= 0) { // read failed
            // FIXME: GB_export_error!
            return 0;
        }
        ptr += read_len;
        to_read -= read_len;
    }
    return size;
}

ssize_t arb_socket_write(int socket, const char* ptr, size_t size) {
    size_t to_write = size;

    while (to_write) {
#ifdef MSG_NOSIGNAL
        // Linux has MSG_NOSIGNAL, but not SO_NOSIGPIPE
        // prevent SIGPIPE here
        ssize_t write_len = send(socket, ptr, to_write, MSG_NOSIGNAL);
        // Note: if valgrind warns about uninitialized bytes sent,
        // one common reason are parameters passed as int (instead of long).
        // Affected functions are aisc_put, aisc_nput and aisc_create.
#else
        ssize_t write_len = write(socket, ptr, to_write);
#endif
        if (write_len <= 0) { // write failed 
            if (errno == EPIPE) {
                fputs("pipe broken\n", stderr);
            }

            // FIXME: GB_export_error!
            return -1;
        }
        ptr += write_len;
        to_write -= write_len;
    }
    return 0;
}

static GB_ERROR arb_open_unix_socket(char* name, bool do_connect, int *fd);
static GB_ERROR arb_open_tcp_socket(char* name, bool do_connect, int *fd);

/**
 * Opens and prepares a socket
 *
 * If @param name begins with ":", the remainder is shell expanded and 
 * a unix socket is created. If @param contains no ":" it must be numeric,
 * giving the TCPport number to open. If @param contains a ":" in the middle,
 * the first part is considered the hostname and the latter part the port.
 *
 * @param  name          name of port   {[<host>:]<port>|:<filename>} 
 * @param  do_connect    connect if true (client), otherwise bind (server)
 * @param  *fd           file descriptor of opened socket (out) or 0 (never returns <0!)
 * @param  filename_out  filename of unix socket (out)
 *                       must be NULp or allocated (will be freed)
 *
 * @result NULp if all went fine     -> *fd>0
 *         "" if could not connect   -> *fd==0
 *         otherwise error message   -> *fd==0
 */
GB_ERROR arb_open_socket(const char* name, bool do_connect, int *fd, char** filename_out) {
    GB_ERROR error = NULp;
    *fd            = 0;

    if (!name || strlen(name) == 0) {
        error = "Error opening socket: empty name";
    }
    else if (name[0] == ':') {
        // expand variables in path
        char *filename    = arb_shell_expand(name+1);
        error             = GB_incur_error();
        if (!error) error = arb_open_unix_socket(filename, do_connect, fd);

        if (error) {
            free(filename);
        }
        else {
            reassign(*filename_out, filename);
        }
    } 
    else {
        char *socket_name = ARB_strdup(name);
        error = arb_open_tcp_socket(socket_name, do_connect, fd);
        free(socket_name);
        freenull(*filename_out);
    }

    if (error) {
        *fd = 0;
    }
    else {
        arb_assert(*fd>0);
    }

    return error;
}

static GB_ERROR arb_open_unix_socket(char* filename, bool do_connect, int *fd) {
    GB_ERROR error = NULp;

    // create structure for connect/bind
    sockaddr_un unix_socket;
    unix_socket.sun_family = AF_UNIX;
    if (strlen(filename)+1 > sizeof(unix_socket.sun_path)) {
        error = GBS_global_string("Failed to create unix socket: "
                                  "\"%s\" is longer than the allowed %zu characters",
                                  filename, sizeof(unix_socket.sun_path));
    }
    else {
        strncpy(unix_socket.sun_path, filename, sizeof(unix_socket.sun_path));

        // create socket
        *fd = socket(PF_UNIX, SOCK_STREAM, 0);
        if (*fd < 0) {
            error = GBS_global_string("Failed to create unix socket: %s", strerror(errno));
        }
        else {
            // connect or bind socket
            if (do_connect) {
                if (connect(*fd, (sockaddr*)&unix_socket, sizeof(sockaddr_un))) {
                    if (errno == ECONNREFUSED || errno == ENOENT) {
                        error = "";
                    }
                    else {
                        error = GBS_global_string("Failed to connect unix socket \"%s\": %s (%i)",
                                                  filename, strerror(errno), errno);
                    }
                }
            }
            else {
                struct stat stt;
                if (!stat(filename, &stt)) {
                    if (!S_ISSOCK(stt.st_mode)) {
                        error = GBS_global_string("Failed to create unix socket at \"%s\": file exists"
                                                  " and is not a socket", filename);
                    }
                    else if (unlink(filename)) {
                        error = GBS_global_string("Failed to create unix socket at \"%s\": cannot remove"
                                                  " existing socket", filename);
                    }
                }
                if (!error && bind(*fd, (sockaddr*)&unix_socket, sizeof(sockaddr_un))) {
                    error = GBS_global_string("Failed to bind unix socket \"%s\": %s",
                                              filename, strerror(errno));
                }
            }

#ifdef SO_NOSIGPIPE
            if (!error) {
                // OSX has SO_NOSIGPIPE but not MSG_NOSIGNAL
                // prevent SIGPIPE here:
                int one = 1;
                if (setsockopt(*fd, SOL_SOCKET, SO_NOSIGPIPE, (const char *)&one, sizeof(one))){
                    fprintf(stderr, "Warning: setsockopt(...NOSIGPIPE...) failed: %s", strerror(errno));
                }
            }
#endif

            if (error) {
                close(*fd);
                *fd = -1;
            }
        }
    }

    return error;
}

static GB_ERROR arb_open_tcp_socket(char* name, bool do_connect, int *fd) {
    GB_ERROR error = NULp;

    // create socket
    *fd = socket(PF_INET, SOCK_STREAM, 0);
    if (*fd < 0) {
        error = GBS_global_string("Failed to create tcp socket: %s", strerror(errno));
    }
    else {
        // create sockaddr struct
        sockaddr_in tcp_socket;
        tcp_socket.sin_family = AF_INET;

        struct hostent *he;
        // get port and host
        char *p = strchr(name, ':');
        if (!p) { // <port>
            tcp_socket.sin_port = htons(atoi(name));
            arb_gethostbyname(arb_gethostname(), he, error);
        }
        else { // <host>:<port>
            tcp_socket.sin_port = htons(atoi(p+1));
            p[0]='\0';
            arb_gethostbyname(name, he, error);
            p[0]=':';
        }
        if (tcp_socket.sin_port == 0) {
            error = "Cannot open tcp socket on port 0. Is the port name malformed?";
        }
        if (!error) {
            memcpy(&tcp_socket.sin_addr, he->h_addr_list[0], he->h_length);

            int one = 1;
            if (do_connect) {
                if (connect(*fd, (sockaddr*)&tcp_socket, sizeof(tcp_socket))) {
                    if (errno == ECONNREFUSED) {
                        error = "";
                    } else {
                        error = GBS_global_string("Failed to connect TCP socket \"%s\": %s",
                                                  name, strerror(errno));
                    }
                }
            }
            else { // no connect (bind)
                if (setsockopt(*fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one))) {
                    fprintf(stderr, "Warning: setsockopt(...REUSEADDR...) failed: %s", strerror(errno));
                }
                if (bind(*fd, (sockaddr*)&tcp_socket, sizeof(tcp_socket))) {
                    error = GBS_global_string("Failed to bind TCP socket \"%s\": %s",
                                              name, strerror(errno));
                }
            }

            if (setsockopt(*fd, IPPROTO_TCP, TCP_NODELAY, &one, sizeof(one))) {
                fprintf(stderr, "Warning: setsockopt(...TCP_NODELAY...) failed: %s", strerror(errno));
            }
        }

        if (error) {
            close(*fd);
            *fd = -1;
        }
    }
    return error;
}

////////// UNIT TESTS ///////////

#ifdef UNIT_TESTS

#ifndef TEST_UNIT_H
# include <test_unit.h>
#endif
#include <sys/wait.h>
#include <arb_sleep.h>

static int echo_server(const char* portname) {
    int mypid = fork();
    if (mypid) return mypid;
   
    int fd;
    char *filename = NULp;
    GB_ERROR error = arb_open_socket(portname, false, &fd, &filename);
    if (error) {
        exit(1);
    }

    if (listen(fd, 1)) {
        exit(2);
    }

    {
        int cli_fd = accept(fd, NULp, NULp);
        if (cli_fd < 0) {
            exit(3);
        }

        char buf[500];
        ssize_t n;
        while(1) {
            n = sizeof(buf);
            n = arb_socket_read(cli_fd, buf, n);
            if (n == 0) break;
            n = arb_socket_write(cli_fd, buf, n);
            if (n == -1) break;;
            if (strcmp(buf, "exit") == 0) break;
        }

        close(cli_fd);
    }

    close(fd);
    if (filename) {
        unlink(filename);
        free(filename);
    }
   
    exit(0);
}

#if !defined(DARWIN)
// TEST_DISABLED_OSX: this test may fail randomly (always timeouts under OSX)
void TEST_open_socket() {
    int fd;
    char *filename = NULp;
    int server_pid, server_status;

    const int XTRABUF = 20; // silences buffer overflow warnings

    // set up port names
    char *unix_socket = arb_shell_expand(":$ARBHOME/UNIT_TESTER/sok/test.socket");
    char tcp_socket[sizeof("65536")+XTRABUF], tcp_socket2[sizeof("localhost:65536")+XTRABUF];
    {
        // select port to use for tcp_sockets randomly to reduce probability
        // of conflicts between parallel builds on same host
        srand(time(NULp)+getpid());

        const int RANGE    = 100;
        const int PORT_MIN = 32039;
        const int PORT_MAX = PORT_MIN+RANGE-1;

        int order[RANGE]; // create random order of numbers in [0..RANGE-1]
        {
            int pos[RANGE];
            for (int p = 0; p<RANGE; ++p) pos[p] = p;

            for (int o = 0; o<RANGE; ++o) {
                int limit = RANGE-o;
                int take  = (rand()*double(limit))/RAND_MAX;
                TEST_EXPECT(take>=0 && take<limit);
                order[o]  = pos[take];
                for (int t = take+1; t<limit; ++t) {
                    pos[t-1] = pos[t];
                }
            }
        }

        int port = -1;
        for (int o = 0; o<RANGE; o++) {
            port = PORT_MIN+order[o];
            TEST_EXPECT(port>=PORT_MIN && port<=PORT_MAX);

            snprintf(tcp_socket, sizeof(tcp_socket), "%i", port);
            const char *err = arb_open_socket(tcp_socket, true, &fd, &filename);
            if (!err) { // connected
                TEST_EXPECT_EQUAL(close(fd), 0);
            }
            else if (err[0] == '\0') { // could not connect
                // found a free socket
                break;
            }
            else { // other error
                TEST_EXPECT_NULL(err);
            }
        }
        TEST_REJECT(port == -1);
        snprintf(tcp_socket2, sizeof(tcp_socket2), "localhost:%i", port);
    }

    // Test opening server sockets
    TEST_EXPECT_NULL(arb_open_socket(tcp_socket, false, &fd, &filename));
    TEST_EXPECT(fd>0);
    TEST_EXPECT_NULL(filename);
    TEST_EXPECT_EQUAL(close(fd), 0);

    TEST_EXPECT_NULL(arb_open_socket(tcp_socket2, false, &fd, &filename));
    TEST_EXPECT(fd>0);
    TEST_EXPECT_NULL(filename);
    TEST_EXPECT_EQUAL(close(fd), 0);

    TEST_EXPECT_NULL(arb_open_socket(unix_socket, false, &fd, &filename));
    TEST_EXPECT(fd>0);
    TEST_REJECT_NULL(filename);
    TEST_EXPECT_EQUAL(close(fd), 0);
    TEST_EXPECT_EQUAL(unlink(filename), 0);
    freenull(filename);

    // Test connecting to existing tcp socket
    server_pid = echo_server(tcp_socket);
    TEST_REJECT_ZERO(server_pid);

    {
        ARB_timeout maxconnect(10, SEC);
        GB_ERROR    res = "";

        while (!maxconnect.passed()) {
            res = arb_open_socket(tcp_socket, true, &fd, &filename);
            if (!res || res[0]) break; // accept 'could not connect'
            ARB_sleep(30, MS);
        }
        TEST_EXPECT_NULL(res); // randomly failed (in older revisions)
    }
    TEST_EXPECT(fd>0);
    TEST_EXPECT_NULL(filename);
    TEST_EXPECT_EQUAL(close(fd), 0);
    TEST_EXPECT_EQUAL(server_pid, waitpid(server_pid, &server_status, 0));

    // Test connecting to closed socket
    TEST_EXPECT_EQUAL("", arb_open_socket(tcp_socket, true, &fd, &filename));
    TEST_EXPECT_EQUAL("", arb_open_socket(unix_socket, true, &fd, &filename));
    
    // Test connecting to existing unix socket
    server_pid = echo_server(unix_socket);
    TEST_REJECT_ZERO(server_pid);
    {
        ARB_timeout maxconnect(10, SEC);
        GB_ERROR    res = "";

        while (!maxconnect.passed()) {
            res = arb_open_socket(unix_socket, true, &fd, &filename);
            if (!res || res[0]) break; // accept 'could not connect'
            ARB_sleep(30, MS);
        }
        TEST_EXPECT_NULL(res); // randomly failed (in older revisions)
    }
    TEST_EXPECT(fd>0);

    // Test read/write
    char send_buf[500], recv_buf[500];
    for (unsigned int i=0; i < sizeof(send_buf); i++) {
        send_buf[i]=i % 64 + '0';
    }
    send_buf[sizeof(send_buf)-1]='\0';

    TEST_EXPECT_NULL(arb_socket_write(fd, send_buf, sizeof(send_buf)));
    TEST_EXPECT_EQUAL(sizeof(recv_buf), arb_socket_read(fd, recv_buf, sizeof(recv_buf)));
    TEST_EXPECT_EQUAL(send_buf, recv_buf);
    TEST_EXPECT_NULL(arb_socket_write(fd, send_buf, sizeof(send_buf)));
    TEST_EXPECT_EQUAL(sizeof(recv_buf), arb_socket_read(fd, recv_buf, sizeof(recv_buf)));
    TEST_EXPECT_EQUAL(send_buf, recv_buf);

    // Test sigpipe (writing to closed socket)
    // tell server to die:
    strcpy(send_buf, "exit"); 
    TEST_EXPECT_NULL(arb_socket_write(fd, send_buf, sizeof(send_buf)));
    TEST_EXPECT_EQUAL(sizeof(recv_buf), arb_socket_read(fd, recv_buf, sizeof(recv_buf)));
    // wait for server to die
    TEST_EXPECT_EQUAL(server_pid, waitpid(server_pid, &server_status, 0));
    // try writing to closed pipe
    TEST_EXPECT_EQUAL(-1, arb_socket_write(fd, send_buf, sizeof(send_buf)));

    TEST_EXPECT_EQUAL(close(fd), 0);
    freenull(filename);
    
    free(unix_socket);
}
TEST_PUBLISH(TEST_open_socket);

#endif

#endif // UNIT_TESTS