/*      $Id: http.c,v 1.17 2023/04/19 12:58:16 jsg Exp $ */
/*
 * Copyright (c) 2016 Kristaps Dzonsons <kristaps@bsd.lv>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/socket.h>

#include <arpa/inet.h>
#include <netinet/in.h>

#include <ctype.h>
#include <err.h>
#include <limits.h>
#include <netdb.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <tls.h>
#include <unistd.h>

#include "http.h"

/*
 * A buffer for transferring HTTP/S data.
 */
struct  httpxfer {
        char            *hbuf;    /* header transfer buffer */
        size_t           hbufsz;  /* header buffer size */
        int              headok;  /* header has been parsed */
        char            *bbuf;    /* body transfer buffer */
        size_t           bbufsz;  /* body buffer size */
        int              bodyok;  /* body has been parsed */
        char            *headbuf; /* lookaside buffer for headers */
        struct httphead *head;    /* parsed headers */
        size_t           headsz;  /* number of headers */
};

/*
 * An HTTP/S connection object.
 */
struct  http {
        int                fd;     /* connected socket */
        short              port;   /* port number */
        struct source      src;    /* endpoint (raw) host */
        char              *path;   /* path to request */
        char              *host;   /* name of endpoint host */
        struct tls        *ctx;    /* if TLS */
        writefp            writer; /* write function */
        readfp             reader; /* read function */
};

struct tls_config *tlscfg;

static ssize_t
dosysread(char *buf, size_t sz, const struct http *http)
{
        ssize_t  rc;

        rc = read(http->fd, buf, sz);
        if (rc == -1)
                warn("%s: read", http->src.ip);
        return rc;
}

static ssize_t
dosyswrite(const void *buf, size_t sz, const struct http *http)
{
        ssize_t  rc;

        rc = write(http->fd, buf, sz);
        if (rc == -1)
                warn("%s: write", http->src.ip);
        return rc;
}

static ssize_t
dotlsread(char *buf, size_t sz, const struct http *http)
{
        ssize_t  rc;

        do {
                rc = tls_read(http->ctx, buf, sz);
        } while (rc == TLS_WANT_POLLIN || rc == TLS_WANT_POLLOUT);

        if (rc == -1)
                warnx("%s: tls_read: %s", http->src.ip,
                    tls_error(http->ctx));
        return rc;
}

static ssize_t
dotlswrite(const void *buf, size_t sz, const struct http *http)
{
        ssize_t  rc;

        do {
                rc = tls_write(http->ctx, buf, sz);
        } while (rc == TLS_WANT_POLLIN || rc == TLS_WANT_POLLOUT);

        if (rc == -1)
                warnx("%s: tls_write: %s", http->src.ip,
                    tls_error(http->ctx));
        return rc;
}

int
http_init(void)
{
        if (tlscfg != NULL)
                return 0;

        tlscfg = tls_config_new();
        if (tlscfg == NULL) {
                warn("tls_config_new");
                goto err;
        }

        if (tls_config_set_ca_file(tlscfg, tls_default_ca_cert_file()) == -1) {
                warn("tls_config_set_ca_file: %s", tls_config_error(tlscfg));
                goto err;
        }

        return 0;

 err:
        tls_config_free(tlscfg);
        tlscfg = NULL;

        return -1;
}

static ssize_t
http_read(char *buf, size_t sz, const struct http *http)
{
        ssize_t  ssz, xfer;

        xfer = 0;
        do {
                if ((ssz = http->reader(buf, sz, http)) < 0)
                        return -1;
                if (ssz == 0)
                        break;
                xfer += ssz;
                sz -= ssz;
                buf += ssz;
        } while (ssz > 0 && sz > 0);

        return xfer;
}

static int
http_write(const char *buf, size_t sz, const struct http *http)
{
        ssize_t  ssz, xfer;

        xfer = sz;
        while (sz > 0) {
                if ((ssz = http->writer(buf, sz, http)) < 0)
                        return -1;
                sz -= ssz;
                buf += (size_t)ssz;
        }
        return xfer;
}

void
http_disconnect(struct http *http)
{
        int rc;

        if (http->ctx != NULL) {
                /* TLS connection. */
                do {
                        rc = tls_close(http->ctx);
                } while (rc == TLS_WANT_POLLIN || rc == TLS_WANT_POLLOUT);

                if (rc < 0)
                        warnx("%s: tls_close: %s", http->src.ip,
                            tls_error(http->ctx));

                tls_free(http->ctx);
        }
        if (http->fd != -1) {
                if (close(http->fd) == -1)
                        warn("%s: close", http->src.ip);
        }

        http->fd = -1;
        http->ctx = NULL;
}

void
http_free(struct http *http)
{

        if (http == NULL)
                return;
        http_disconnect(http);
        free(http->host);
        free(http->path);
        free(http->src.ip);
        free(http);
}

struct http *
http_alloc(const struct source *addrs, size_t addrsz,
    const char *host, short port, const char *path)
{
        struct sockaddr_storage ss;
        int              family, fd, c;
        socklen_t        len;
        size_t           cur, i = 0;
        struct http     *http;

        /* Do this while we still have addresses to connect. */
again:
        if (i == addrsz)
                return NULL;
        cur = i++;

        /* Convert to PF_INET or PF_INET6 address from string. */

        memset(&ss, 0, sizeof(struct sockaddr_storage));

        if (addrs[cur].family == 4) {
                family = PF_INET;
                ((struct sockaddr_in *)&ss)->sin_family = AF_INET;
                ((struct sockaddr_in *)&ss)->sin_port = htons(port);
                c = inet_pton(AF_INET, addrs[cur].ip,
                    &((struct sockaddr_in *)&ss)->sin_addr);
                len = sizeof(struct sockaddr_in);
        } else if (addrs[cur].family == 6) {
                family = PF_INET6;
                ((struct sockaddr_in6 *)&ss)->sin6_family = AF_INET6;
                ((struct sockaddr_in6 *)&ss)->sin6_port = htons(port);
                c = inet_pton(AF_INET6, addrs[cur].ip,
                    &((struct sockaddr_in6 *)&ss)->sin6_addr);
                len = sizeof(struct sockaddr_in6);
        } else {
                warnx("%s: unknown family", addrs[cur].ip);
                goto again;
        }

        if (c < 0) {
                warn("%s: inet_ntop", addrs[cur].ip);
                goto again;
        } else if (c == 0) {
                warnx("%s: inet_ntop", addrs[cur].ip);
                goto again;
        }

        /* Create socket and connect. */

        fd = socket(family, SOCK_STREAM, 0);
        if (fd == -1) {
                warn("%s: socket", addrs[cur].ip);
                goto again;
        } else if (connect(fd, (struct sockaddr *)&ss, len) == -1) {
                warn("%s: connect", addrs[cur].ip);
                close(fd);
                goto again;
        }

        /* Allocate the communicator. */

        http = calloc(1, sizeof(struct http));
        if (http == NULL) {
                warn("calloc");
                close(fd);
                return NULL;
        }
        http->fd = fd;
        http->port = port;
        http->src.family = addrs[cur].family;
        http->src.ip = strdup(addrs[cur].ip);
        http->host = strdup(host);
        http->path = strdup(path);
        if (http->src.ip == NULL || http->host == NULL || http->path == NULL) {
                warn("strdup");
                goto err;
        }

        /* If necessary, do our TLS setup. */

        if (port != 443) {
                http->writer = dosyswrite;
                http->reader = dosysread;
                return http;
        }

        http->writer = dotlswrite;
        http->reader = dotlsread;

        if ((http->ctx = tls_client()) == NULL) {
                warn("tls_client");
                goto err;
        } else if (tls_configure(http->ctx, tlscfg) == -1) {
                warnx("%s: tls_configure: %s",
                        http->src.ip, tls_error(http->ctx));
                goto err;
        }

        if (tls_connect_socket(http->ctx, http->fd, http->host) != 0) {
                warnx("%s: tls_connect_socket: %s, %s", http->src.ip,
                    http->host, tls_error(http->ctx));
                goto err;
        }

        return http;
err:
        http_free(http);
        return NULL;
}

struct httpxfer *
http_open(const struct http *http, const void *p, size_t psz)
{
        char            *req;
        int              c;
        struct httpxfer *trans;

        if (p == NULL) {
                c = asprintf(&req,
                    "GET %s HTTP/1.0\r\n"
                    "Host: %s\r\n"
                    "\r\n",
                    http->path, http->host);
        } else {
                c = asprintf(&req,
                    "POST %s HTTP/1.0\r\n"
                    "Host: %s\r\n"
                    "Content-Type: application/ocsp-request\r\n"
                    "Content-Length: %zu\r\n"
                    "\r\n",
                    http->path, http->host, psz);
        }
        if (c == -1) {
                warn("asprintf");
                return NULL;
        } else if (!http_write(req, c, http)) {
                free(req);
                return NULL;
        } else if (p != NULL && !http_write(p, psz, http)) {
                free(req);
                return NULL;
        }

        free(req);

        trans = calloc(1, sizeof(struct httpxfer));
        if (trans == NULL)
                warn("calloc");
        return trans;
}

void
http_close(struct httpxfer *x)
{

        if (x == NULL)
                return;
        free(x->hbuf);
        free(x->bbuf);
        free(x->headbuf);
        free(x->head);
        free(x);
}

/*
 * Read the HTTP body from the wire.
 * If invoked multiple times, this will return the same pointer with the
 * same data (or NULL, if the original invocation returned NULL).
 * Returns NULL if read or allocation errors occur.
 * You must not free the returned pointer.
 */
char *
http_body_read(const struct http *http, struct httpxfer *trans, size_t *sz)
{
        char             buf[BUFSIZ];
        ssize_t          ssz;
        void            *pp;
        size_t           szp;

        if (sz == NULL)
                sz = &szp;

        /* Have we already parsed this? */

        if (trans->bodyok > 0) {
                *sz = trans->bbufsz;
                return trans->bbuf;
        } else if (trans->bodyok < 0)
                return NULL;

        *sz = 0;
        trans->bodyok = -1;

        do {
                /* If less than sizeof(buf), at EOF. */
                if ((ssz = http_read(buf, sizeof(buf), http)) < 0)
                        return NULL;
                else if (ssz == 0)
                        break;

                pp = recallocarray(trans->bbuf,
                    trans->bbufsz, trans->bbufsz + ssz, 1);
                if (pp == NULL) {
                        warn("recallocarray");
                        return NULL;
                }
                trans->bbuf = pp;
                memcpy(trans->bbuf + trans->bbufsz, buf, ssz);
                trans->bbufsz += ssz;
        } while (ssz == sizeof(buf));

        trans->bodyok = 1;
        *sz = trans->bbufsz;
        return trans->bbuf;
}

struct httphead *
http_head_get(const char *v, struct httphead *h, size_t hsz)
{
        size_t   i;

        for (i = 0; i < hsz; i++) {
                if (strcmp(h[i].key, v))
                        continue;
                return &h[i];
        }
        return NULL;
}

/*
 * Look through the headers and determine our HTTP code.
 * This will return -1 on failure, otherwise the code.
 */
int
http_head_status(const struct http *http, struct httphead *h, size_t sz)
{
        int              rc;
        unsigned int     code;
        struct httphead *st;

        if ((st = http_head_get("Status", h, sz)) == NULL) {
                warnx("%s: no status header", http->src.ip);
                return -1;
        }

        rc = sscanf(st->val, "%*s %u %*s", &code);
        if (rc < 0) {
                warn("sscanf");
                return -1;
        } else if (rc != 1) {
                warnx("%s: cannot convert status header", http->src.ip);
                return -1;
        }
        return code;
}

/*
 * Parse headers from the transfer.
 * Malformed headers are skipped.
 * A special "Status" header is added for the HTTP status line.
 * This can only happen once http_head_read has been called with
 * success.
 * This can be invoked multiple times: it will only parse the headers
 * once and after that it will just return the cache.
 * You must not free the returned pointer.
 * If the original header parse failed, or if memory allocation fails
 * internally, this returns NULL.
 */
struct httphead *
http_head_parse(const struct http *http, struct httpxfer *trans, size_t *sz)
{
        size_t           hsz, szp;
        struct httphead *h;
        char            *cp, *ep, *ccp, *buf;

        if (sz == NULL)
                sz = &szp;

        /*
         * If we've already parsed the headers, return the
         * previously-parsed buffer now.
         * If we have errors on the stream, return NULL now.
         */

        if (trans->head != NULL) {
                *sz = trans->headsz;
                return trans->head;
        } else if (trans->headok <= 0)
                return NULL;

        if ((buf = strdup(trans->hbuf)) == NULL) {
                warn("strdup");
                return NULL;
        }
        hsz = 0;
        cp = buf;

        do {
                if ((cp = strstr(cp, "\r\n")) != NULL)
                        cp += 2;
                hsz++;
        } while (cp != NULL);

        /*
         * Allocate headers, then step through the data buffer, parsing
         * out headers as we have them.
         * We know at this point that the buffer is NUL-terminated in
         * the usual way.
         */

        h = calloc(hsz, sizeof(struct httphead));
        if (h == NULL) {
                warn("calloc");
                free(buf);
                return NULL;
        }

        *sz = hsz;
        hsz = 0;
        cp = buf;

        do {
                if ((ep = strstr(cp, "\r\n")) != NULL) {
                        *ep = '\0';
                        ep += 2;
                }
                if (hsz == 0) {
                        h[hsz].key = "Status";
                        h[hsz++].val = cp;
                        continue;
                }

                /* Skip bad headers. */
                if ((ccp = strchr(cp, ':')) == NULL) {
                        warnx("%s: header without separator", http->src.ip);
                        continue;
                }

                *ccp++ = '\0';
                while (isspace((unsigned char)*ccp))
                        ccp++;
                h[hsz].key = cp;
                h[hsz++].val = ccp;
        } while ((cp = ep) != NULL);

        trans->headbuf = buf;
        trans->head = h;
        trans->headsz = hsz;
        return h;
}

/*
 * Read the HTTP headers from the wire.
 * If invoked multiple times, this will return the same pointer with the
 * same data (or NULL, if the original invocation returned NULL).
 * Returns NULL if read or allocation errors occur.
 * You must not free the returned pointer.
 */
char *
http_head_read(const struct http *http, struct httpxfer *trans, size_t *sz)
{
        char             buf[BUFSIZ];
        ssize_t          ssz;
        char            *ep;
        void            *pp;
        size_t           szp;

        if (sz == NULL)
                sz = &szp;

        /* Have we already parsed this? */

        if (trans->headok > 0) {
                *sz = trans->hbufsz;
                return trans->hbuf;
        } else if (trans->headok < 0)
                return NULL;

        *sz = 0;
        ep = NULL;
        trans->headok = -1;

        /*
         * Begin by reading by BUFSIZ blocks until we reach the header
         * termination marker (two CRLFs).
         * We might read into our body, but that's ok: we'll copy out
         * the body parts into our body buffer afterward.
         */

        do {
                /* If less than sizeof(buf), at EOF. */
                if ((ssz = http_read(buf, sizeof(buf), http)) < 0)
                        return NULL;
                else if (ssz == 0)
                        break;
                pp = realloc(trans->hbuf, trans->hbufsz + ssz);
                if (pp == NULL) {
                        warn("realloc");
                        return NULL;
                }
                trans->hbuf = pp;
                memcpy(trans->hbuf + trans->hbufsz, buf, ssz);
                trans->hbufsz += ssz;
                /* Search for end of headers marker. */
                ep = memmem(trans->hbuf, trans->hbufsz, "\r\n\r\n", 4);
        } while (ep == NULL && ssz == sizeof(buf));

        if (ep == NULL) {
                warnx("%s: partial transfer", http->src.ip);
                return NULL;
        }
        *ep = '\0';

        /*
         * The header data is invalid if it has any binary characters in
         * it: check that now.
         * This is important because we want to guarantee that all
         * header keys and pairs are properly NUL-terminated.
         */

        if (strlen(trans->hbuf) != (uintptr_t)(ep - trans->hbuf)) {
                warnx("%s: binary data in header", http->src.ip);
                return NULL;
        }

        /*
         * Copy remaining buffer into body buffer.
         */

        ep += 4;
        trans->bbufsz = (trans->hbuf + trans->hbufsz) - ep;
        trans->bbuf = malloc(trans->bbufsz);
        if (trans->bbuf == NULL) {
                warn("malloc");
                return NULL;
        }
        memcpy(trans->bbuf, ep, trans->bbufsz);

        trans->headok = 1;
        *sz = trans->hbufsz;
        return trans->hbuf;
}

void
http_get_free(struct httpget *g)
{

        if (g == NULL)
                return;
        http_close(g->xfer);
        http_free(g->http);
        free(g);
}

struct httpget *
http_get(const struct source *addrs, size_t addrsz, const char *domain,
    short port, const char *path, const void *post, size_t postsz)
{
        struct http     *h;
        struct httpxfer *x;
        struct httpget  *g;
        struct httphead *head;
        size_t           headsz, bodsz, headrsz;
        int              code;
        char            *bod, *headr;

        h = http_alloc(addrs, addrsz, domain, port, path);
        if (h == NULL)
                return NULL;

        if ((x = http_open(h, post, postsz)) == NULL) {
                http_free(h);
                return NULL;
        } else if ((headr = http_head_read(h, x, &headrsz)) == NULL) {
                http_close(x);
                http_free(h);
                return NULL;
        } else if ((bod = http_body_read(h, x, &bodsz)) == NULL) {
                http_close(x);
                http_free(h);
                return NULL;
        }

        http_disconnect(h);

        if ((head = http_head_parse(h, x, &headsz)) == NULL) {
                http_close(x);
                http_free(h);
                return NULL;
        } else if ((code = http_head_status(h, head, headsz)) < 0) {
                http_close(x);
                http_free(h);
                return NULL;
        }

        if ((g = calloc(1, sizeof(struct httpget))) == NULL) {
                warn("calloc");
                http_close(x);
                http_free(h);
                return NULL;
        }

        g->headpart = headr;
        g->headpartsz = headrsz;
        g->bodypart = bod;
        g->bodypartsz = bodsz;
        g->head = head;
        g->headsz = headsz;
        g->code = code;
        g->xfer = x;
        g->http = h;
        return g;
}

#if 0
int
main(void)
{
        struct httpget  *g;
        struct httphead *httph;
        size_t           i, httphsz;
        struct source    addrs[2];
        size_t           addrsz;

#if 0
        addrs[0].ip = "127.0.0.1";
        addrs[0].family = 4;
        addrsz = 1;
#else
        addrs[0].ip = "2a00:1450:400a:806::2004";
        addrs[0].family = 6;
        addrs[1].ip = "193.135.3.123";
        addrs[1].family = 4;
        addrsz = 2;
#endif

        if (http_init() == -1)
                errx(EXIT_FAILURE, "http_init");

#if 0
        g = http_get(addrs, addrsz, "localhost", 80, "/index.html");
#else
        g = http_get(addrs, addrsz, "www.google.ch", 80, "/index.html",
            NULL, 0);
#endif

        if (g == NULL)
                errx(EXIT_FAILURE, "http_get");

        httph = http_head_parse(g->http, g->xfer, &httphsz);
        warnx("code: %d", g->code);

        for (i = 0; i < httphsz; i++)
                warnx("head: [%s]=[%s]", httph[i].key, httph[i].val);

        http_get_free(g);
        return (EXIT_SUCCESS);
}
#endif